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  • 151. Di Cecilia, Serena
    et al.
    Zhang, Fan
    Sancho, Ana
    Li, SiDe
    Aguiló, Francesca
    Department of Pharmacological Sciences, Icahn School of Medicine at Mount Sinai, New York; Department of Pediatrics, Icahn School of Medicine at Mount Sinai, New York; Department of Genetics and Genomic Sciences, Icahn School of Medicine at Mount Sinai, New York.
    Sun, Yifei
    Rengasamy, Madhumitha
    Zhang, Weijia
    Del Vecchio, Luigi
    Salvatore, Francesco
    Walsh, Martin J.
    RBM5-AS1 Is Critical for Self-Renewal of Colon Cancer Stem-like Cells2016In: Cancer Research, ISSN 0008-5472, E-ISSN 1538-7445, Vol. 76, no 19, p. 5615-5627Article in journal (Refereed)
    Abstract [en]

    Cancer-initiating cells (CIC) undergo asymmetric growth patterns that increase phenotypic diversity and drive selection for chemotherapeutic resistance and tumor relapse. WNT signaling is a hallmark of colon CIC, often caused by APC mutations, which enable activation of β-catenin and MYC Accumulating evidence indicates that long noncoding RNAs (lncRNA) contribute to the stem-like character of colon cancer cells. In this study, we report enrichment of the lncRNA RBM5-AS1/LUST during sphere formation of colon CIC. Its silencing impaired WNT signaling, whereas its overexpression enforced WNT signaling, cell growth, and survival in serum-free media. RBM5-AS1 has been little characterized previously, and we determined it to be a nuclear-retained transcript that selectively interacted with β-catenin. Mechanistic investigations showed that silencing or overexpression of RBM5-AS1 caused a respective loss or retention of β-catenin from TCF4 complexes bound to the WNT target genes SGK1, YAP1, and MYC Our work suggests that RBM5-AS1 activity is critical for the functional enablement of colon cancer stem-like cells. Furthermore, it defines the mechanism of action of RBM5-AS1 in the WNT pathway via physical interactions with β-catenin, helping organize transcriptional complexes that sustain colon CIC function. 

  • 152.
    di Summa, Pietro G
    et al.
    University of Manchester, University Hospital of Lausanne.
    Kalbermatten, Daniel F
    University Hospital of Basel.
    Raffoul, Wassim
    University Hospital of Lausanne.
    Terenghi, Giorgio
    University of Manchester.
    Kingham, Paul J
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Anatomy. University of Manchester.
    Extracellular matrix molecules enhance the neurotrophic effect of Schwann cell-like differentiated adipose-derived stem cells and increase cell survival under stress conditions2013In: Tissue Engineering. Part A, ISSN 1937-3341, E-ISSN 1937-335X, Vol. 19, no 3-4, p. 368-379Article in journal (Refereed)
    Abstract [en]

    Since the first reports of induction of adipose-derived stem cells (ASC) into neuronal and glial cell phenotypes, expectations have increased regarding their use in tissue engineering applications for nerve repair. Cell adhesion to extracellular matrix (ECM) is a basic feature of survival, differentiation, and migration of Schwann cells (SC) during nerve regeneration, and fibronectin and laminin are two key molecules of this process. Interaction between ECM and SC-like differentiated ASC (dASC) could potentially improve the neurotrophic potential of the stem cells. We have investigated the effect of ECM molecules on SC-like dASC in terms of proliferation, adhesion, and cell viability. Fibronectin and laminin did not affect the proliferation of dASC when compared with cell adherent tissue culture plastic, but significantly improved viability and cell attachment when dASC were exposed to apoptotic conditions. To assess the influence of the ECM molecules on dASC neurotrophic activity, dASC were seeded onto ECM-coated culture inserts suspended above dorsal root ganglia (DRG) sensory neurons. Neurite outgrowth of DRG neurons was enhanced when dASC were seeded on fibronectin and laminin when compared with controls. When DRG neurons and dASC were in direct contact on the various surfaces there was significantly enhanced neurite outgrowth and coculture with laminin-conditioned dASC produced the longest neurites. Compared with primary SCs, dASC grown on laminin produced similar levels of neurite outgrowth in the culture insert experiments but neurite length was shorter in the direct contact groups. Anti beta 1 integrin blocking antibody could inhibit baseline and dASC evoked neurite elongation but had no effect on outgrowth mediated by laminin-conditioned dASC. ECM molecules had no effect on the levels of nerve growth factor and brain-derived neurotrophic factor secretion from dASC. The results of the study suggest that ECM molecules can significantly improve the potential of dASC for nerve regeneration.

  • 153.
    Dimitriou, Michael
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Physiology.
    Enhanced Muscle Afferent Signals during Motor Learning in Humans2016In: Current Biology, ISSN 0960-9822, E-ISSN 1879-0445, Vol. 26, no 8, p. 1062-1068Article in journal (Refereed)
    Abstract [en]

    Much has been revealed concerning human motor learning at the behavioral level [1, 2], but less is known about changes in the involved neural circuits and signals. By examining muscle spindle responses during a classic visuomotor adaptation task [3-6] performed by fully alert humans, I found substantial modulation of sensory afferent signals as a function of adaptation state. Specifically, spindle control was independent of concurrent muscle activity but was specific to movement direction (representing muscle lengthening versus shortening) and to different stages of learning. Increased spindle afferent responses to muscle stretch occurring early during learning reflected individual error size and were negatively related to subsequent antagonist activity (i.e., 60-80 ms thereafter). Relative increases in tonic afferent output early during learning were predictive of the subjects' adaptation rate. I also found that independent spindle control during sensory realignment (the "washout" stage) induced afferent signal "linearization" with respect to muscle length (i.e., signals were more tuned to hand position). The results demonstrate for the first time that motor learning also involves independent and state-related modulation of sensory mechanoreceptor signals. The current findings suggest that adaptive motor performance also relies on the independent control of sensors, not just of muscles. I propose that the "gamma" motor system innervating spindles acts to facilitate the acquisition and extraction of task-relevant information at the early stages of sensorimotor adaptation. This designates a more active and targeted role for the human proprioceptive system during motor learning.

  • 154.
    Dimitriou, Michael
    et al.
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Physiology.
    Edin, Benoni B
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Physiology.
    Human muscle spindles act as forward sensory models2010In: Current Biology, ISSN 0960-9822, E-ISSN 1879-0445, Vol. 20, no 19, p. 1763-1767Article in journal (Refereed)
    Abstract [en]

    Modern theories of motor control incorporate forward models that combine sensory information and motor commands to predict future sensory states. Such models circumvent unavoidable neural delays associated with on-line feedback control. Here we show that signals in human muscle spindle afferents during unconstrained wrist and finger movements predict future kinematic states of their parent muscle. Specifically, we show that the discharges of type Ia afferents are best correlated with the velocity of length changes in their parent muscles approximately 100-160 ms in the future and that their discharges vary depending on motor sequences in a way that cannot be explained by the state of their parent muscle alone. We therefore conclude that muscle spindles can act as "forward sensory models": they are affected both by the current state of their parent muscle and by efferent (fusimotor) control, and their discharges represent future kinematic states. If this conjecture is correct, then sensorimotor learning implies learning how to control not only the skeletal muscles but also the fusimotor system.

  • 155. Doherty, Gary J
    et al.
    Lundmark, Richard
    Umeå University, Faculty of Medicine, Department of Medical Biochemistry and Biophysics.
    GRAF1-dependent endocytosis2009In: Biochemical Society Transactions, ISSN 0300-5127, E-ISSN 1470-8752, Vol. 37, no 5, p. 1061-1065Article in journal (Refereed)
    Abstract [en]

    The role of endocytosis in controlling a multitude of cell biological events is well established. Molecular and mechanistic characterization of endocytosis has predominantly focused on CME (clathrin-mediated endocytosis), although many other endocytic pathways have been described. it was recently shown that the BAR (Bin/amphiphysin/Rvs) and Rho GAP (GTPase-activating protein) domain-containing protein GRAF1 (GTPase regulator associated with focal adhesion kinase-1) is found on prevalent, pleiomorphic endocytic membranes, and is essential for the major, clathrin-independent endocytic pathway that these membranes mediate. This pathway is characterized by its ability to internalize GPI (glycosylphosphatidylinositol)anchored proteins, bacterial toxins and large amounts of extracellular fluid. These membrane carriers are highly dynamic and associated with the activity of the small G-protein Cdc42 (cell division cycle 42). in the present paper, we review the role of GRAF1 in this CLIC (clathrin-independent carrier)/GEEC (GPI-anchored protein-enriched early endocytic compartment) endocytic pathway and discuss the current understanding regarding how this multidomain protein functions at the interface between membrane sculpting, small G-protein signalling and endocytosis.

  • 156. Doherty, Gary J.
    et al.
    Åhlund, Monika K.
    Umeå University, Faculty of Medicine, Department of Medical Biochemistry and Biophysics.
    Howes, Mark T.
    Moren, Bjorn
    Parton, Robert G.
    McMahon, Harvey T.
    Lundmark, Richard
    Umeå University, Faculty of Medicine, Department of Medical Biochemistry and Biophysics.
    The endocytic protein GRAF1 is directed to cell-matrix adhesion sites and regulates cell spreading2011In: Molecular Biology of the Cell, ISSN 1059-1524, E-ISSN 1939-4586, Vol. 22, no 22, p. 4380-4389Article in journal (Refereed)
    Abstract [en]

    The rho GTPase-activating protein GTPase regulator associated with focal adhesion kinase-1 (GRAF1) remodels membranes into tubulovesicular clathrin-independent carriers (CLICs) mediating lipid-anchored receptor endocytosis. However, the cell biological functions of this highly prevalent endocytic pathway are unclear. In this article, we present biochemical and cell biological evidence that GRAF1 interacted with a network of endocytic and adhesion proteins and was found enriched at podosome-like adhesions and src-induced podosomes. We further demonstrate that these sites comprise microdomains of highly ordered lipid enriched in GRAF1 endocytic cargo. GRAF1 activity was upregulated in spreading cells and uptake via CLICs was concentrated at the leading edge of migrating cells. Depletion of GRAF1, which inhibits CLIC generation, resulted in profound defects in cell spreading and migration. We propose that GRAF1 remodels membrane microdomains at adhesion sites into endocytic carriers, facilitating membrane turnover during cell morphological changes.

  • 157. Doublet, Vincent
    et al.
    Poeschl, Yvonne
    Gogol-Doering, Andreas
    Alaux, Cedric
    Annoscia, Desiderato
    Aurori, Christian
    Barribeau, Seth M.
    Bedoya-Reina, Oscar C.
    Brown, Mark J. F.
    Bull, James C.
    Flenniken, Michelle L.
    Galbraith, David A.
    Genersch, Elke
    Gisder, Sebastian
    Grosse, Ivo
    Holt, Holly L.
    Hultmark, Dan
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine).
    Lattorff, H. Michael G.
    Le Conte, Yves
    Manfredini, Fabio
    McMahon, Dino P.
    Moritz, Robin F. A.
    Nazzi, Francesco
    Nino, Elina L.
    Nowick, Katja
    van Rij, Ronald P.
    Paxton, Robert J.
    Grozinger, Christina M.
    Unity in defence: honeybee workers exhibit conserved molecular responses to diverse pathogens2017In: BMC Genomics, ISSN 1471-2164, E-ISSN 1471-2164, Vol. 18, article id 207Article in journal (Refereed)
    Abstract [en]

    Background: Organisms typically face infection by diverse pathogens, and hosts are thought to have developed specific responses to each type of pathogen they encounter. The advent of transcriptomics now makes it possible to test this hypothesis and compare host gene expression responses to multiple pathogens at a genome-wide scale. Here, we performed a meta-analysis of multiple published and new transcriptomes using a newly developed bioinformatics approach that filters genes based on their expression profile across datasets. Thereby, we identified common and unique molecular responses of a model host species, the honey bee (Apis mellifera), to its major pathogens and parasites: the Microsporidia Nosema apis and Nosema ceranae, RNA viruses, and the ectoparasitic mite Varroa destructor, which transmits viruses.

    Results: We identified a common suite of genes and conserved molecular pathways that respond to all investigated pathogens, a result that suggests a commonality in response mechanisms to diverse pathogens. We found that genes differentially expressed after infection exhibit a higher evolutionary rate than non-differentially expressed genes. Using our new bioinformatics approach, we unveiled additional pathogen-specific responses of honey bees; we found that apoptosis appeared to be an important response following microsporidian infection, while genes from the immune signalling pathways, Toll and Imd, were differentially expressed after Varroa/virus infection. Finally, we applied our bioinformatics approach and generated a gene co-expression network to identify highly connected (hub) genes that may represent important mediators and regulators of anti-pathogen responses.

    Conclusions: Our meta-analysis generated a comprehensive overview of the host metabolic and other biological processes that mediate interactions between insects and their pathogens. We identified key host genes and pathways that respond to phylogenetically diverse pathogens, representing an important source for future functional studies as well as offering new routes to identify or generate pathogen resilient honey bee stocks. The statistical and bioinformatics approaches that were developed for this study are broadly applicable to synthesize information across transcriptomic datasets. These approaches will likely have utility in addressing a variety of biological questions.

  • 158.
    Doudna, Jennifer A.
    et al.
    Univ Calif Berkeley, Berkeley, CA 94720 USA.
    Charpentier, Emmanuelle
    Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS). Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR). Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine). Helmholtz Ctr Infect Res, Dept Regulat Infect Biol, D-38124 Braunschweig, Germany; Hannover Med Sch, D-30625 Hannover, Germany.
    The new frontier of genome engineering with CRISPR-Cas92014In: Science, ISSN 0036-8075, E-ISSN 1095-9203, Vol. 346, no 6213, p. 1077-+Article, review/survey (Refereed)
    Abstract [en]

    The advent of facile genome engineering using the bacterial RNA-guided CRISPR-Cas9 system in animals and plants is transforming biology. We review the history of CRISPR (clustered regularly interspaced palindromic repeat) biology from its initial discovery through the elucidation of the CRISPR-Cas9 enzyme mechanism, which has set the stage for remarkable developments using this technology to modify, regulate, or mark genomic loci in a wide variety of cells and organisms from all three domains of life. These results highlight a new era in which genomic manipulation is no longer a bottleneck to experiments, paving the way toward fundamental discoveries in biology, with applications in all branches of biotechnology, as well as strategies for human therapeutics.

  • 159.
    Duan, Chen
    et al.
    Medical College of Xi'an Jiaotong University, Xi'an, Shaanxi, China.
    Guo, Xiong
    Medical College of Xi'an Jiaotong University, Xi'an, Shaanxi, China.
    Zhang, Xiao-Dong
    First Affiliated Hospital, Xi'an Jiaotong University, Xi'an, Shaanxi, China.
    Yu, Han-Jie
    Northwest University, Xi'an, Shaanxi, China.
    Yan, Hua
    Second Affiliated Hospital, Xi'an Jiaotong University, Xi'an, Shaanxi, China.
    Gao, Ying
    Second Affiliated Hospital, Xi'an Jiaotong University, Xi'an, Shaanxi, China.
    Ma, Wei-Juan
    Medical College of Xi'an Jiaotong University, Xi'an, Shaanxi, China.
    Gao, Zong-Qiang
    Second Affiliated Hospital, Xi'an Jiaotong University, Xi'an, Shaanxi, China.
    Xu, Peng
    Xi'an Red Cross Hospital, Xi'an, Shaanxi, China.
    Lammi, Mikko
    University of Kuopio, Kuopio, Finland.
    Comparative analysis of gene expression profiles between primary knee osteoarthritis and an osteoarthritis endemic to Northwestern China, Kashin-Beck disease.2010In: Arthritis and Rheumatism, ISSN 0004-3591, E-ISSN 1529-0131, Vol. 62, no 3, p. 771-780, article id 20131229Article in journal (Refereed)
    Abstract [en]

    OBJECTIVE: To investigate the differences in gene expression profiles of adult articular cartilage from patients with Kashin-Beck disease (KBD) versus those with primary knee osteoarthritis (OA).

    METHODS: The messenger RNA expression profiles of articular cartilage from patients with KBD, diagnosed according to the clinical criteria for KBD in China, were compared with those of cartilage from patients with OA, diagnosed according to the Western Ontario and McMaster Universities OA Index. Total RNA was isolated separately from 4 pairs of the KBD and OA cartilage samples, and the expression profiles were evaluated by Agilent 4x44k Whole Human Genome density oligonucleotide microarray analysis. The microarray data for selected transcripts were confirmed by quantitative real-time reverse transcription-polymerase chain reaction (RT-PCR) amplification.

    RESULTS: For 1.2 x 10(4) transcripts, corresponding to 58.4% of the expressed transcripts, 2-fold changes in differential expression were revealed. Expression levels higher in KBD than in OA samples were observed in a mean + or - SD 6,439 + or - 1,041 (14.6 + or - 2.4%) of the transcripts, and expression levels were lower in KBD than in OA samples in 6,147 + or - 1,222 (14.2 + or - 2.8%) of the transcripts. After application of the selection criteria, 1.85% of the differentially expressed genes (P < 0.001 between groups) were detected. These included 233 genes, of which 195 (0.4%) were expressed at higher levels and 38 (0.08%) were expressed at lower levels in KBD than in OA cartilage. Comparisons of the quantitative RT-PCR data supported the validity of our microarray data.

    CONCLUSION: Differences between KBD and OA cartilage exhibited a similar pattern among all 4 of the pairs examined, indicating the presence of disease mechanisms, mainly chondrocyte matrix metabolism, cartilage degeneration, and apoptosis induction pathways, which contribute to cartilage destruction in KBD.

  • 160. Dörr, Tobias
    et al.
    Alvarez, Laura
    Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR). Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine). Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS).
    Delgado, Fernanda
    Davis, Brigid M.
    Cava, Felipe
    Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR). Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine). Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS).
    Waldor, Matthew K.
    A cell wall damage response mediated by a sensor kinase/response regulator pair enables beta-lactam tolerance2016In: Proceedings of the National Academy of Sciences of the United States of America, ISSN 0027-8424, E-ISSN 1091-6490, Vol. 113, no 2, p. 404-409Article in journal (Refereed)
    Abstract [en]

    The bacterial cell wall is critical for maintenance of cell shape and survival. Following exposure to antibiotics that target enzymes required for cell wall synthesis, bacteria typically lyse. Although several cell envelope stress response systems have been well described, there is little knowledge of systems that modulate cell wall synthesis in response to cell wall damage, particularly in Gram-negative bacteria. Here we describe WigK/WigR, a histidine kinase/response regulator pair that enables Vibrio cholerae, the cholera pathogen, to survive exposure to antibiotics targeting cell wall synthesis in vitro and during infection. Unlike wild-type V. cholerae, mutants lacking wigR fail to recover following exposure to cell-wall-acting antibiotics, and they exhibit a drastically increased cell diameter in the absence of such antibiotics. Conversely, overexpression of wigR leads to cell slimming. Overexpression of activated WigR also results in increased expression of the full set of cell wall synthesis genes and to elevated cell wall content. WigKR-dependent expression of cell wall synthesis genes is induced by various cell-wall-acting antibiotics as well as by overexpression of an endogenous cell wall hydrolase. Thus, WigKR appears to monitor cell wall integrity and to enhance the capacity for increased cell wall production in response to damage. Taken together, these findings implicate WigKR as a regulator of cell wall synthesis that controls cell wall homeostasis in response to antibiotics and likely during normal growth as well.

  • 161. Earp, Caroline
    et al.
    Rowbotham, Samuel
    Merényi, Gábor
    Umeå University, Faculty of Medicine, Department of Medical Biochemistry and Biophysics.
    Chabes, Andrei
    Umeå University, Faculty of Medicine, Department of Medical Biochemistry and Biophysics. Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS).
    Cha, Rita S
    S phase block following MEC1ATR inactivation occurs without severe dNTP depletion2015In: Biology open, ISSN 2046-6390, Vol. 4, no 12, p. 1739-1743Article in journal (Refereed)
    Abstract [en]

    Inactivation of Mec1, the budding yeast ATR, results in a permanent S phase arrest followed by chromosome breakage and cell death during G2/M. The S phase arrest is proposed to stem from a defect in Mec1-mediated degradation of Sml1, a conserved inhibitor of ribonucleotide reductase (RNR), causing a severe depletion in cellular dNTP pools. Here, the casual link between the S phase arrest, Sml1, and dNTP-levels is examined using a temperature sensitive mec1 mutant. In addition to S phase arrest, thermal inactivation of Mec1 leads to constitutively high levels of Sml1 and an S phase arrest. Expression of a novel suppressor, GIS2, a conserved mRNA binding zinc finger protein, rescues the arrest without down-regulating Sml1 levels. The dNTP pool in mec1 is reduced by ∼17% and GIS2 expression restores it, but only partially, to ∼93% of a control. We infer that the permanent S phase block following Mec1 inactivation can be uncoupled from its role in Sml1 down-regulation. Furthermore, unexpectedly modest effects of mec1 and GIS2 on dNTP levels suggest that the S phase arrest is unlikely to result from a severe depletion of dNTP pool as assumed, but a heightened sensitivity to small changes in its availability.

  • 162.
    Edin, Sofia
    Umeå University, Faculty of Medicine, Molecular Biology (Faculty of Medicine).
    Calmodulin mediated regulation of NF-kappaB in lymphocytes2008Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    NF-κB transcription factors are regulators of a wide spectrum of genes involved in immune responses and inflammation as well as cellular proliferation and survival. Transcriptionally competent NF-κB dimers are retained in the cytoplasm of resting cells by binding to inhibitors of NF-κB (IκBs). Stimuli that activate NF-κB converge on the activation of the IκB kinase (IKK), resulting in phosphorylation and subsequent proteasomal degradation of IκB. This releases functional NF-κB dimers that rapidly move to the nucleus where they regulate transcription of NF-κB-dependent target genes. The study of signalling to NF-κB from T and B lymphocyte antigen receptors is a field of intense investigation, and much attention is focused on the complex of the molecular scaffolding proteins Carma1, Bcl10 and MALT1. Together, these are crucial for the organisation of a structure beneath the activated receptor, termed the immunological synapse. IKK is recruited to this structure and becomes activated, subsequently leading to activation of NF-κB.

    Calcium (Ca2+) is a ubiquitous intracellular messenger that is involved in the regulation of numerous aspects of cellular function, including transcription. NF-κB activity is known to be regulated by changes in intracellular Ca2+ levels, such as those created by antigen receptor activation, but the mechanisms are to a large extent undefined. Ca2+ signals in cells are transmitted predominantly by the ubiquitous Ca2+ sensor protein calmodulin (CaM). Signalling that increases the intracellular Ca2+ concentration leads to binding of Ca2+ to CaM, which changes its structure, thereby allowing it to interact with a new range of target proteins.

    The studies of NF-κB signalling in lymphocytes presented here reveal that CaM is involved, both directly and indirectly, in the regulation of NF-κB. CaM was found to interact directly and in a Ca2+-dependent manner with the NF-κB proteins RelA and c-Rel after their signal-induced release from IκB. The interaction of CaM with c-Rel, but not RelA, was found to be inhibitory for its nuclear accumulation and transcriptional activity on Ca2+-regulated IL-2 and GM-CSF promoters; thus, CaM binding was found to differentially regulate c-Rel and RelA in lymphocytes. CaM was also shown to interact directly and in a Ca2+-dependent manner with Bcl10. The interaction was mapped to the Carma1-interacting CARD domain of Bcl10 and was found to have a negative effect on the ability of Bcl10 to bind to Carma1. Binding of CaM to Bcl10 also had a negative effect on activation of NF-κB after T cell receptor stimulation, since a point mutant of Bcl10 with reduced binding to CaM showed increased activation of an NF-κB reporter in Jurkat T cells, which was further enhanced by TCR-activating stimuli.

    In addition, CaM was found to positively regulate NF-κB activation indirectly through CaM-dependent kinase II (CaMKII). Inhibitors of CaM and CaMKII were shown to inhibit IκBα degradation in lymphocytes induced by phorbol ester or T cell receptor stimulation. The actions of CaMKII were mapped to a point upstream of IKK activation and further studies revealed that CaMKII is recruited to the immunological synapse, where it inducibly interacts with and phosphorylates Bcl10 at multiple sites. Phosphorylation of Bcl10 by CaMKII was shown to be important for the ability of Bcl10 to activate NF-κB, since mutation of the phosphorylation sites of Bcl10 inhibited Bcl10-induced transcriptional activity of NF-κB, in part by preventing signalinduced ubiquitination and degradation of Bcl10.

  • 163.
    Edling, Charlotte
    Umeå University, Faculty of Medicine, Medical Biosciences.
    Receptor tyrosine kinase c-Kit signalling in hematopoietic progenitor cells2006Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The receptor tyrosine kinase (RTK) c-Kit is expressed in hematopoietic stem and progenitor cells, mast cells and in several non-hematopoietic tissues. In the hematopoietic system c-Kit and its ligand Steel Factor (SF, aka Stem Cell Factor) are critical for proliferation, survival and differentiation. Mutations in either receptor or ligand lead to lethal anaemia, hematopoietic stem cell defects, mast cell deficiency and a series of non-hematological defects.

    The aims of the studies included in this thesis are to describe the signalling pathways downstream c-Kit in hematopoietic stem/progenitor cells and to further analyse the role of c-Kit signalling in fundamental biological functions.

    To study c-Kit signalling in the hematopoietic system we have employed hematopoietic stem cell-like cell lines which share many properties with primary hematopoietic stem cells in vitro and in vivo, including surface markers, multipotentiality, capacity for self-renewal and long term repopulation. In paper I we demonstrate that upon SF activation the RTK c-Kit is autophosphorylated and downstream signalling mediators are transiently activated. Surprisingly we find that the c-Kit mediated activation of the MAPK pathway is dependent on the activation of phosphoinositide 3-kinase (PI3K) in hematopoietic progenitor cells and that differentiation of these progenitors to mast cells results in a signalling switch where Raf activation changes from PI3K dependent to PI3K independent. We here establish that PI3K activity is required for viability and proliferation of hematopoietic progenitor cells. In paper II we studied the conventional protein kinase C (cPKC) involvement in c-Kit signalling. We observe that the cPKCs can phosphorylate c-Kit on serine 746 and that this phosphorylation negatively regulates the activation of the receptor. We demonstrate that inhibition of this negative phosphorylation results in dramatically increased protein kinase B (PKB) activation and as a consequence inhibition of cPKCs rescues cells from starvation induced apoptosis. Moreover we exhibit that the cPKCs are necessary for full activation of extracellular signal-regulated kinase (Erk) and that impaired PKC activity leads to hampered proliferation. In paper III we demonstrate that in addition to the cPKCs also the novel PKC is required for Erk activation and proliferation. Furthermore we present results indicating that PKC negatively regulates differentiation of bone marrow.

    In conclusion, with the studies in this thesis we display details in the signalling pathways induced upon RTK c-Kit activation and we demonstrate that c-Kit has significant effects on hematopoietic cell-physiology.

  • 164. Edqvist, Petra
    et al.
    Bröms, Jeanette E
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine).
    Steggo, Peter
    Forsberg, Åke
    Francis, Matthew
    Characterization of the tetratricopeptide repeats in type III secretion chaperones- mediators of substrate binding and specificityManuscript (Other academic)
  • 165.
    Edqvist, Petra J
    et al.
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine). Umeå University, Faculty of Science and Technology, Department of Molecular Biology (Faculty of Science and Technology).
    Francis, Matthew S
    Examination of LcrH type III secretion chaperone function during Yersinia-eukaryotic cell contactManuscript (Other academic)
  • 166.
    Eerola, Iiro
    et al.
    Department of Medical Biochemistry and Molecular Biology, University of Turku, Turku, Finland.
    Salminen, Heli
    Department of Medical Biochemistry and Molecular Biology, University of Turku, Turku, Finland.
    Lammi, Pirkko
    Department of Anatomy, University of Kuopio, Kuopio, Finland.
    Lammi, Mikko
    Department of Anatomy, University of Kuopio, Kuopio, Finland.
    von der Mark, Klaus
    Institute of Experimental Medicine, Friedrich Alexander University of Erlangen-Nuremberg, Erlangen, Germany.
    Vuorio, Eero
    Department of Medical Biochemistry and Molecular Biology, University of Turku, Turku, Finland.
    Säämänen, Anna-Marja
    Department of Medical Biochemistry and Molecular Biology, University of Turku, Turku, Finland.
    Type X collagen, a natural component of mouse articular cartilage: association with growth, aging, and osteoarthritis.1998In: Arthritis and Rheumatism, ISSN 0004-3591, E-ISSN 1529-0131, Vol. 41, no 7, p. 1287-1295, article id 9663487Article in journal (Refereed)
    Abstract [en]

    OBJECTIVE: To perform a systematic study on the production and deposition of type X collagen in developing, aging, and osteoarthritic (OA) mouse articular cartilage.

    METHODS: Immunohistochemistry was employed to define the distribution of type X collagen and Northern analyses to determine the messenger RNA levels as an indicator of the synthetic activity of the protein.

    RESULTS: Type X collagen was observed in the epiphyseal and articular cartilage of mouse knee joints throughout development and growth. Type X collagen deposition in the transitional zone of articular cartilage became evident toward cessation of growth, at the age of 2-3 months. The most intense staining for type X collagen was limited to the tidemark, the border between uncalcified and calcified cartilage. Northern analysis confirmed that the type X collagen gene is also transcribed by articular cartilage chondrocytes. Intense immunostaining was observed in the areas of OA lesions, specifically, at sites of osteophyte formation and surface fibrillation. Type X collagen deposition was also seen in degenerating menisci.

    CONCLUSION: This study demonstrates that type X collagen is a natural component of mouse articular cartilage throughout development, growth, and aging. This finding and the deposition of type X collagen at sites of OA lesions suggest that type X collagen may have a role in providing structural support for articular cartilage.

  • 167.
    Eklöf, Vincy
    Umeå University, Faculty of Medicine, Department of Medical Biosciences, Pathology.
    Faecal markers and mutations in diagnosis and prognosis of colorectal cancer2018Licentiate thesis, comprehensive summary (Other academic)
  • 168.
    Eklöf, Vincy
    et al.
    Umeå University, Faculty of Medicine, Department of Medical Biosciences, Pathology.
    Lundgren, David
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Medicine.
    Karling, Pontus
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Medicine.
    Wikberg, Maria L.
    Umeå University, Faculty of Medicine, Department of Medical Biosciences, Pathology.
    Edin, Sofia
    Umeå University, Faculty of Medicine, Department of Medical Biosciences, Pathology.
    Löfgren Burström, Anna
    Umeå University, Faculty of Medicine, Department of Medical Biosciences, Pathology.
    Rutegård, Jörgen
    Umeå University, Faculty of Medicine, Department of Surgical and Perioperative Sciences, Surgery.
    Palmqvist, Richard
    Umeå University, Faculty of Medicine, Department of Medical Biosciences, Pathology.
    The combined diagnostic value of faecal haemoglobin and calprotectin in colorectal cancerManuscript (preprint) (Other academic)
  • 169.
    Eklöf, Vincy
    et al.
    Umeå University, Faculty of Medicine, Department of Medical Biosciences, Pathology.
    Wikberg, Maria L.
    Umeå University, Faculty of Medicine, Department of Medical Biosciences, Pathology.
    Edin, Sofia
    Umeå University, Faculty of Medicine, Department of Medical Biosciences, Pathology.
    Dahlin, Anna M.
    Umeå University, Faculty of Medicine, Department of Medical Biosciences, Pathology.
    Jonsson, Björn-Anders
    Umeå University, Faculty of Medicine, Department of Medical Biosciences, Pathology.
    Öberg, Å.
    Umeå University, Faculty of Medicine, Department of Surgical and Perioperative Sciences.
    Rutegård, Jörgen
    Umeå University, Faculty of Medicine, Department of Surgical and Perioperative Sciences, Surgery.
    Palmqvist, Richard
    Umeå University, Faculty of Medicine, Department of Medical Biosciences, Pathology.
    The prognostic role of KRAS, BRAF, PIK3CA and PTEN in colorectal cancer2013In: British Journal of Cancer, ISSN 0007-0920, E-ISSN 1532-1827, Vol. 108, no 10, p. 2153-2163Article in journal (Refereed)
    Abstract [en]

    Background Mutations in KRAS, BRAF, PIK3CA and PTEN expression have been in focus to predict the effect of epidermal growth factor receptor-blocking therapy in colorectal cancer (CRC). Here, information on these four aberrations was collected and combined to a Quadruple index and used to evaluate the prognostic role of these factors in CRC. Patients We analysed the mutation status in KRAS, BRAF and PIK3CA and PTEN expression in two separate CRC cohorts, Northern Sweden Health Disease Study (NSHDS; n = 197) and Colorectal Cancer in Umea Study (CRUMS; n = 414). A Quadruple index was created, where Quadruple index positivity specifies cases with any aberration in KRAS, BRAF, PIK3CA or PTEN expression. Results Quadruple index positive tumours had a worse prognosis, significant in the NSHDS but not in the CRUMS cohort (NSHDS; P = 0.003 and CRUMS; P = 0.230) in univariate analyses but significance was lost in multivariate analyses. When analysing each gene separately, only BRAF was of prognostic significance in the NSHDS cohort (multivariate HR 2.00, 95% CI: 1.16-3.43) and KRAS was of prognostic significance in the CRUMS cohort (multivariate HR 1.48, 95% CI: 1.02-2.16). Aberrations in PIK3CA and PTEN did not add significant prognostic information. Conclusions Our results suggest that establishment of molecular subgroups based on KRAS and BRAF mutation status is important and should be considered in future prognostic studies in CRC.

  • 170.
    Elfving, Nils
    Umeå University, Faculty of Medicine, Department of Medical Biochemistry and Biophysics.
    Functional studies of Mediator in Arabidopsis thaliana and Saccharomyces cerevisiae2013Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Mediator has been shown to be essential for regulation of RNA Polymerase II mediated transcription. Mediator functions as an interface between the general transcriptional machinery and a multitude of DNA binding transcriptional regulators, although the molecular mechanism for the process is elusive. Mediator is a large complex of over twenty subunits, most of which are conserved from yeast to plants to mammals. Many of these subunits are essential for viability in yeast, and mutations in the corresponding genes have global effects on transcription. Mediator was originally identified in Saccharomyces cerevisiae, but has since been described in most eukaryotes. However, until recently the Mediator complex was not identified in plants. This thesis describes the first successful identification and isolation of the Mediator complex from the plant Arabidopsis thaliana. By raising antibodies against candidate A. thaliana Mediator subunits, we were able to purify a multisubunit protein complex. Mass spectrometry and bioinformatics analysis allowed us to identify 21 of these subunits as conserved Mediator components and six as A. thaliana specific subunits. Some of the genes that encode the identified Mediator subunits had earlier been described as components of specific regulatory pathways controlling for example cell proliferation and flowering time. Subsequent genetic analysis confirmed that the A. thaliana Mediator complex is important for several plant signaling pathways, including flowering and stress pathways. This thesis also describes identification of regulators that interact with the A. thaliana Mediator subunit Med25, previously identified as PFT1 (Phytochrome and Flowering Time 1) and implicated in regulation of flowering time in response to light quality. Finally, we describe the function of Mediator in S. cerevisiae using genome-wide approaches. We have carried out a transcriptional switch where half of the genome changes expression and determined Mediator occupancy across the genome before and after such a switch, using ChIP-SEQ on tagged subunits from different Mediator domains. Unexpectedly, we find that Mediator occupancy is limited at most promoters. However, at the highly occupied promoters, we see different modes of changes in occupancy as a result of the transcriptional switch. These highly occupied promoters control genes involved in different stress response pathways. Thus, our results suggest that Mediator function and composition differ considerably between different promoters.

  • 171.
    Elfving, Nils
    et al.
    Umeå University, Faculty of Medicine, Department of Medical Biochemistry and Biophysics.
    Chereji, Razvan
    Department of Physics and Astronomy and BioMaPS Institute for Quantitative Biology, Rutgers University.
    Larsson, Miriam
    Umeå University, Faculty of Medicine, Department of Medical Biochemistry and Biophysics.
    Morozov, Alexandre
    Department of Physics and Astronomy and BioMaPS Institute for Quantitative Biology, Rutgers University.
    Broach, James
    Department of Molecular Biology, Princeton University.
    Björklund, Stefan
    Umeå University, Faculty of Medicine, Department of Medical Biochemistry and Biophysics.
    Mediator exists in multiple forms and is predominantly associated to promoters with low nuclesome densityManuscript (preprint) (Other academic)
  • 172.
    Elfving, Nils
    et al.
    Umeå University, Faculty of Medicine, Department of Medical Biochemistry and Biophysics.
    Davoine, Céline
    Umeå University, Faculty of Medicine, Department of Medical Biochemistry and Biophysics.
    Benlloch, Reyes
    Blomberg, Jeanette
    Umeå University, Faculty of Medicine, Department of Medical Biochemistry and Biophysics.
    Brännström, Kristoffer
    Umeå University, Faculty of Medicine, Department of Medical Biochemistry and Biophysics.
    Müller, Dörte
    Nilsson, Anders
    Ulfstedt, Mikael
    Ronne, Hans
    Wingsle, Gunnar
    Nilsson, Ove
    Björklund, Stefan
    Umeå University, Faculty of Medicine, Department of Medical Biochemistry and Biophysics.
    The Arabidopsis thaliana Med25 mediator subunit integrates environmental cues to control plant development2011In: Proceedings of the National Academy of Sciences of the United States of America, ISSN 0027-8424, E-ISSN 1091-6490, Vol. 108, no 20, p. 8245-8250Article in journal (Refereed)
    Abstract [en]

    Development in plants is controlled by abiotic environmental cues such as day length, light quality, temperature, drought, and salinity. These signals are sensed by a variety of systems and transmitted by different signal transduction pathways. Ultimately, these pathways are integrated to control expression of specific target genes, which encode proteins that regulate development and differentiation. The molecular mechanisms for such integration have remained elusive. We here show that a linear 130-amino-acids-long sequence in the Med25 subunit of the Arabidopsis thaliana Mediator is a common target for the drought response element binding protein 2A, zinc finger homeodomain 1, and Myb-like transcription factors which are involved in different stress response pathways. In addition, our results show that Med25 together with drought response element binding protein 2A also function in repression of PhyB-mediated light signaling and thus integrate signals from different regulatory pathways.

  • 173.
    Elo, Mika
    et al.
    Department of Anatomy, University of Kuopio, Kuopio, Finland.
    Kaarniranta, Kai
    Department of Opthalmology, Kuopio University Hospital, Kuopio, Finland.
    Helminen, Heikki
    Department of Anatomy, University of Kuopio, Kuopio, Finland.
    Lammi, Mikko
    Department of Anatomy, University of Kuopio, Kuopio, Finland.
    Hsp90 inhibitor geldanamycin increases hsp70 mRNA stabilisation but fails to activate HSF1 in cells exposed to hydrostatic pressure.2005In: Biochimica et Biophysica Acta, ISSN 0006-3002, E-ISSN 1878-2434, Vol. 1743, no 1-2, p. 115-119, article id 15777846Article in journal (Refereed)
    Abstract [en]

    High hydrostatic pressure (HP) increases Hsp70 protein and mRNA levels by increasing the mRNA half-life without activation of HSF1 transcription factor. We investigated whether this change in gene expression requires Hsp90, previously shown to regulate hsp70 genes via HSF1. In HeLa cells, both HP and Hsp90 inhibitor geldanamycin (GA) up-regulated Hsp70 expression through mRNA stabilisation. GA, unlike HP, increased HSF1 activation. However, when exposures were used together a marked Hsp70 response was observed with mRNA stabilisation without coincidence of HSF1 activation. Our data suggests that Hsp90 is involved in hsp70 mRNA stabilisation and the HSF1 activation can be suppressed by high HP.

  • 174.
    Elo, Mika
    et al.
    Department of Anatomy, University of Kuopio, Kuopio, Finland.
    Karjalainen, Hannu
    Department of Anatomy, University of Kuopio, Kuopio, Finland.
    Sironen, Reijo
    Department of Anatomy, University of Kuopio, Kuopio, Finland.
    Valmu, Leena
    Institute of Biotechnololgy, Biocenter Viikki, University of Helsinki, Helsinki, Finland.
    Redpath, Nicholas
    Celltech R & D, Slough, United Kingdom.
    Browne, Gareth
    Division of Molecular Physiology, School of Life Sciences, University of Dundee, Dundee, United Kingdom.
    Kalkkinen, Nisse
    Institute of Biotechnololgy, Biocenter Viikki, University of Helsinki, Helsinki, Finland.
    Helminen, Heikki
    Department of Anatomy, University of Kuopio, Kuopio, Finland.
    Lammi, Mikko
    Department of Anatomy, University of Kuopio, Kuopio, Finland.
    High hydrostatic pressure inhibits the biosynthesis of eukaryotic elongation factor-2.2005In: Journal of Cellular Biochemistry, ISSN 0730-2312, E-ISSN 1097-4644, Vol. 94, no 3, p. 497-507, article id 15534876Article in journal (Refereed)
    Abstract [en]

    High continuous hydrostatic pressure is known to inhibit the total cellular protein synthesis. In this study, our goal was to identify pressure-regulated proteins by using two dimensional gel electrophoresis and mass spectrometry. This analysis showed that under 30 MPa continuous hydrostatic pressure the biosynthesis of eukaryotic elongation factor-2 (eEF-2) was inhibited both in HeLa carcinoma and T/C28a4 chondrocytic cell lines. Western blot analysis of HeLa cells revealed that the cellular protein level of eEF-2 decreased by 40%-50% within 12 h of the pressure treatment. However, the steady-state mRNA level of eEF-2 was not affected by the pressure. Cycloheximide addition after 4 h-pressure treatment suggested that the half-life of eEF-2 protein was shorter in pressurized cells. eEF-2 is responsible for the translocation of ribosome along the specific mRNA during translation, and its phosphorylation prevents the ribosomal translocation. Therefore, increased phosphorylation of eEF-2 was considered as one mechanism that could explain the reduced level of protein synthesis in pressurized HeLa cell cultures. However, Western blot analysis with an antibody recognizing the Thr56-phosphorylated form of eEF-2 showed that phosphorylation of eEF-2 was not elevated in pressurized samples. In conclusion, the inhibition of protein synthesis under high pressure occurs independent of the phosphorylation of eEF-2. However, this inhibition may result from the decrease of cellular eEF-2 protein.

  • 175.
    Elo, Mika
    et al.
    Department of Anatomy, University of Kuopio, Kuopio, Finland.
    Sironen, Reijo
    Department of Anatomy, University of Kuopio, Kuopio, Finland.
    Kaarniranta, Kai
    Department of Anatomy, University of Kuopio, Kuopio, Finland.
    Auriola, Seppo
    Department of Pharmaceutical Chemistry, University of Kuopio, Kuopio, Finland.
    Helminen, Heikki
    Department of Anatomy, University of Kuopio, Kuopio, Finland.
    Lammi, Mikko
    Department of Anatomy, University of Kuopio, Kuopio, Finland.
    Differential regulation of stress proteins by high hydrostatic pressure, heat shock, and unbalanced calcium homeostasis in chondrocytic cells.2000In: Journal of Cellular Biochemistry, ISSN 0730-2312, E-ISSN 1097-4644, Vol. 79, no 4, p. 610-619, article id 10996852Article in journal (Refereed)
    Abstract [en]

    High hydrostatic pressure (HP) has recently been shown to increase cellular heat shock protein 70 (Hsp70) level in a specific way that does not involve transcriptional activation of the gene, but rather the stabilisation of the mRNA for Hsp70. In this study, we investigated whether there are other observable changes caused by HP stress, and compared them with those induced by certain other forms of stressors. A chondrocytic cell line T/C28a4 was exposed to 30 MPa continuous HP, heat shock at 43 degrees C, and increased cytosolic calcium concentration by the addition of sarco-endoplasmic reticulum Ca(2+) ATPase inhibitor thapsigargin (25 nM) or calcium ionophore A23187 (1 microM) in the cultures. The protein synthesis was studied by in vitro metabolic labelling followed by one- and two-dimensional polyacrylamide gel electrophoresis, and mass spectrometry was utilized to confirm the identity of the protein spots on two-dimensional gels. Continuous 30 MPa HP increased remarkably the relative labelling of Hsp70. Labelling of Hsp90 was also increased by 15-20%, although no clear change was evident at the protein level in Western blots. Elevated intracellular Ca(2+) concentration induced by thapsigargin and calcium ionophore A23187 increased mainly the synthesis of glucose-regulated protein 78 (Grp78/BiP), whereas Hsp70 and Hsp90 were decreased by the treatment. Heat shock was the strongest inducer of Hsp70 and Hsp90. This study further confirmed the induction of Hsp70 in chondrocytic cells exposed to high HP, but it also showed that calcium-mediated responses are unlikely to cause the stress response observed in the hydrostatically pressurized cells.

  • 176.
    Elo, Mika
    et al.
    Department of Anatomy, University of Kuopio, Kuopio, Finland.
    Sironen, Reijo
    Department of Anatomy, University of Kuopio, Kuopio, Finland.
    Karjalainen, Hannu
    Department of Anatomy, University of Kuopio, Kuopio, Finland.
    Kaarniranta, Kai
    Department of Anatomy, University of Kuopio, Kuopio, Finland.
    Helminen, Heikki
    Department of Anatomy, University of Kuopio, Kuopio, Finland.
    Lammi, Mikko
    Department of Anatomy, University of Kuopio, Kuopio, Finland.
    Specific induction of heat shock protein 90beta by high hydrostatic pressure.2003In: Biorheology, ISSN 0006-355X, E-ISSN 1878-5034, Vol. 40, no 1-3, p. 141-146, article id 12454398Article in journal (Refereed)
    Abstract [en]

    In chondrocytes, a low-amplitude intermittent hydrostatic pressure induces production of extracellular matrix molecules, while high hydrostatic pressure inhibits it. High pressure increases cellular heat shock protein 70 level in a number of cell types on account of increased stabilisation of the heat shock protein 70 mRNA. In our experiments, only bovine primary chondrocytes, but not an immortalized chondrocytic cell line, could resist the induction of the stress response in the presence of continuous 30 MPa hydrostatic pressure. We have recently shown that protein synthesis is required for the stabilization. According to two-dimensional gel electrophoresis the synthesis of heat shock protein 90 was also increased in a chondrocytic cell line and in HeLa cells, and mass spectrometric analysis suggested that the induction was rather due to increase in heat shock protein 90beta than in heat shock protein 90alpha. The stress response was rather intense in HeLa cells, therefore, we investigated the effect of continuous 30 MPa hydrostatic pressure on the expression of the two heat shock protein 90 genes in HeLa cells using Northern and Western blot analyses. Heat shock protein 90beta mRNA level increased within 6 hours of exposure to 30 MPa hydrostatic pressure, while hsp90alpha level remained stable. At protein level there was a clear increase in the heat shock protein 90beta/heat shock protein 90alpha ratio, too. These results show a specific regulation of stress proteins in cells exposed to high hydrostatic pressure.

  • 177.
    Englezou, Pavlos C.
    et al.
    University of Manchester.
    Degli Esposti, Mauro
    University of Manchester.
    Wiberg, Mikael
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Anatomy. Umeå University, Faculty of Medicine, Department of Surgical and Perioperative Sciences, Hand Surgery.
    Reid, Adam J.
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Anatomy. University of Manchester.
    Terenghi, Giorgio
    University of Manchester.
    Mitochondrial involvement in sensory neuronal cell death and survival2012In: Experimental Brain Research, ISSN 0014-4819, E-ISSN 1432-1106, Vol. 221, no 4, p. 357-367Article in journal (Refereed)
    Abstract [en]

    Peripheral nerve injuries (PNI) are continuing to be an ever-growing socio-economic burden affecting mainly the young working population and the current clinical treatments to PNI provide a poor clinical outcome involving significant loss of sensation. Thus, our understanding of the underlying factors responsible for the extensive loss of the sensory cutaneous subpopulation in the dorsal root ganglia (DRG) that occurs following injury needs to be improved. The current investigations focus in identifying visual cues of mitochondria-related apoptotic events in the various subpopulations of sensory cutaneous neurons. Sensory neuronal subpopulations were identified using FastBlue retrograde labelling following axotomy. Specialised fluorogenic probes, MitoTracker Red and MitoTracker Orange, were employed to visualise the dynamic changes of the mitochondrial population of neurons. The results reveal a fragmented mitochondrial network in sural neurons following apoptosis, whereas a fused elongated mitochondrial population is present in sensory proprioceptive muscle neurons following tibial axotomy. We also demonstrate the neuroprotective properties of NAC and ALCAR therapy in vitro. The dynamic mitochondrial network breaks down following oxidative exposure to hydrogen peroxide (H2O2), but reinitiates fusion after NAC and ALCAR therapy. In conclusion, this study provides both qualitative and quantitative evidence of the susceptibility of sensory cutaneous sub-population in apoptosis and of the neuroprotective effects of NAC and ALCAR treatment on H2O2-challenged neurons.

  • 178.
    Enow, Constance
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine).
    Studies of pore-forming bacterial protein toxins in Escherichia coli2014Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Escherichia coli, a Gram-negative bacterium, which can be classified into three groups: the commensal, intestinal pathogenic (IPEC) and extra-intestinal pathogenic (ExPEC) E. coli. The cytolysin A (ClyA) protein, a 34-kDa pore-forming toxin, encoded by a gene found in both non-pathogenic and pathogenic E. coli and in Salmonella enterica serovars Typhi and Paratyphi. It mediates a cytotoxic effect on various mammalian cells. ClyA is released by E. coli via outer membrane vesicles (OMVs) after reaching the periplasm via an unknown mechanism through the inner membrane. The gene is silenced by mutations in some of the most studied ExPEC strains suggesting that the locus would be subject to patho-adaptive alterations.

    To study if the mutations of the clyA gene in E. coli strains was particular to certain strains, the sequences of the clyA gene locus of a set of ExPEC isolates and of the E. coli collection of reference strains (ECOR) were compared. The ExPEC strains – uropathogenic and neonatal meningitis E. coli (UPEC and NMEC) strains contained various ΔclyA alleles. Next, a functional clyA gene locus was restored and tagged with luxAB in the chromosome of the UPEC strain 536. Luciferase activity of the bacteria carrying the restored gene showed that the clyA gene expression is highly increased at the late logarithmic growth phase when compared to the non-pathogenic E. coli K-12 strain. A higher transcriptional level of the clyA+ gene was observed when the SfaX regulatory protein was heterologously overproduced. It was concluded that the clyA+ gene is expressed at elevated levels in the UPEC strain and this is at least in part due to the SfaX/PapX transcriptional regulators.

    Studies of clyA::phoA fusions obtained by transposon TnphoA insertion mutagenesis showed that the first 12 amino acid residues of ClyA was sufficient for translocation of the protein chimera into the periplasm and to the OMVs. The role of the two cysteine residues in ClyA for protein translocation was tested by introducing substitution mutations. The results indicated that the C-terminal Cys (ClyAC 285S) is important for localization and/or stability of the protein in the periplasm. Structural analysis of ClyAwt purified from the periplasm revealed that the protein forms dimeric complexes. Upon treatment with the reducing agent DTT the ClyA protein readily assembled into typical pore complexes as revealed by electron miscroscopic analysis. In conclusion, the ClyA protein is present in the periplasm in a conformation that prevents it from forming pores in the bacterial membranes.

    Vibrio cholerae cytolysin (VCC) is a pore-forming toxin which induces lysis of mammalian cells by forming transmembrane channels. Although the biophysical activities of VCC were well studied, there was no detailed analysis of VCC secretion. Our study demonstrated that a fraction of the VCC was secreted in association with OMVs. OMV-associated VCC from the wild type V. cholerae strain V:5/04 is biologically active as shown by toxic effects on mammalian cells, interestingly, OMV-associated VCC was more active than purified VCC. Both environmental and clinical V. cholerae isolates transport VCC via OMVs. In addition, when the vcc gene is heterologously expressed in E. coli, OMV-associated secretion of VCC was also observed. We suggest that OMV-mediated release of VCC is a feature shared with ClyA.

  • 179.
    Enow, Constance
    et al.
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine).
    Oscarsson, Jan
    Umeå University, Faculty of Medicine, Department of Odontology.
    Mizunoe, Yoshimitsu
    Huang, Shengua
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Meier, Elke
    Benz, Roland
    Sauer-Eriksson, Elisabeth
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Wai, Sun Nyunt
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine).
    Uhlin, Bernt Eric
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine).
    Localization and structure of the ClyA protein in Escherichia coli before secretion and pore-formationManuscript (preprint) (Other academic)
  • 180.
    Erba, Paolo
    et al.
    University Hospitals of Basel and Lausanne.
    Terenghi, Giorgio
    University of Manchester.
    Kingham, Paul J
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Anatomy.
    Neural differentiation and therapeutic potential of adipose tissue derived stem cells2010In: Current stem cell research & therapy, ISSN 1574-888X, Vol. 5, no 2, p. 153-160Article, review/survey (Refereed)
    Abstract [en]

    Neural tissue has historically been regarded as having poor regenerative capacity but recent advances in the growing fields of tissue engineering and regenerative medicine have opened new hopes for the treatment of nerve injuries and neurodegenerative disorders. Adipose tissue has been shown to contain a large quantity of adult stem cells (ASC). These cells can be easily harvested with low associated morbidity and because of their potential to differentiate into multiple cell types, their use has been suggested for a wide variety of therapeutic applications. In this review we examine the evidence indicating that ASC can stimulate nerve regeneration by both undergoing neural differentiation and through the release of a range of growth factors. We also discuss some of the issues that need to be addressed before ASC can be developed as an effective cellular therapy for the treatment of neural tissue disorders.

  • 181.
    Eriksson, Therese
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine).
    Exploiting Drosophila as a model system for studying anaplastic lymphoma kinase in vivo2010Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Anaplastic Lymphoma Kinase (ALK) is a Receptor Tyrosine Kinase (RTK) and an oncogene associated with several human diseases, but its normal function in humans and other vertebrates is unclear. Drosophila melanogaster has an ALK homolog, demonstrating that the RTK has been conserved throughout evolution. This makes Drosophila a suitable model organism for studying not only Drosophila ALK function, but also to study mammalian forms of ALK. In Drosophila the ligand Jeb activates ALK, initiating signaling crucial for visceral mesoderm development. The activating ligand for mammalian ALK is unclear, and for this reason Drosophila was employed in a cross-species approach to investigate whether Drosophila Jeb can activate mouse ALK. Jeb is unable to activate mouse ALK, and therefore mouse ALK is unable to substitute for and rescue the Drosophila ALK mutant phenotype. This suggests that there has been significant evolution in the ALK-ligand relationship between the mouse and Drosophila.

    In humans ALK has recently been shown to be involved in the development of neuroblastoma, a cancer tumor in children. I have developed a Drosophila model for examining human gain of function ALK mutants found in neuroblastoma patients. The various ALK variants have acquired point mutations in the kinase domain that have been predicted to activate the RTK in a constitutive and ligand independent manner. When expressed in the fly eye, active human ALK mutants result in a rough eye phenotype, while inactive wild type ALK does not, due to the lack of an activating ligand in the fly. In this way  several of the ALK mutations identified in neuroblastoma patients could be confirmed to be activated in a ligand independent manner. Moreover, a novel ALK mutant; ALKF1174S, was discovered in a neuroblastoma patient and was in the Drosophila model shown to be a gain of function mutation, and a previously predicted gain of function mutation; ALKI1250T, was shown to be a kinase dead mutation. This fly model can also be used for testing ALK selective inhibitors, for identifying activating ligands for human ALK and for identifying conserved components of the ALK signaling pathway.

    Gut musculature development in Drosophila is dependent on ALK signaling, while somatic muscle development is not. Proteins of the Wasp-Scar signaling network regulate Arp2/3-complex mediated actin polymerization, and I have investigated their function in visceral and somatic muscle fusion. I found that Verprolin and other members of this protein family are essential for somatic but not visceral muscle development. Despite fusion defects in both tissues in Verprolin and other examined mutants, gut development proceeds, suggesting that fusion is not crucial for visceral mesoderm development. Hence the actin polymerization machinery functions in both somatic and visceral muscle fusion, but this process only appears to be essential in somatic muscle development.

  • 182.
    Ermert, David
    et al.
    Umeå University, Faculty of Medicine, Department of Clinical Microbiology, Clinical Bacteriology.
    Niemiec, Maria Joanna
    Umeå University, Faculty of Medicine, Department of Clinical Microbiology, Clinical Bacteriology.
    Röhm, Marc
    Umeå University, Faculty of Medicine, Department of Clinical Microbiology, Clinical Bacteriology.
    Glenthøj, Andreas
    Department of Hematology, National University Hospital, Copenhagen, Denmark..
    Borregaard, Niels
    Department of Hematology, National University Hospital, Copenhagen, Denmark..
    Urban, Constantin F.
    Umeå University, Faculty of Medicine, Department of Clinical Microbiology, Clinical Bacteriology.
    Candida albicans escapes from mouse neutrophils2013In: Journal of Leukocyte Biology, ISSN 0741-5400, E-ISSN 1938-3673, Vol. 94, no 2, p. 223-236Article in journal (Refereed)
    Abstract [en]

    Candida albicans, the most commonly isolated human fungal pathogen, is able to grow as budding yeasts or filamentous forms, such as hyphae. The ability to switch morphology has been attributed a crucial role for the pathogenesis of C. albicans. To mimic disseminated candidiasis in humans, the mouse is the most widely used model organism. Neutrophils are essential immune cells to prevent opportunistic mycoses. To explore potential differences between the rodent infection model and the human host, we compared the interactions of C. albicans with neutrophil granulocytes from mice and humans. We revealed that murine neutrophils exhibited a significantly lower ability to kill C. albicans than their human counterparts. Strikingly, C. albicans yeast cells formed germ tubes upon internalization by murine neutrophils, eventually rupturing the neutrophil membrane and thereby, killing the phagocyte. On the contrary, growth and subsequent escape of C. albicans are blocked inside human neutrophils. According to our findings, this blockage in human neutrophils might be a result of higher levels of MPO activity and the presence of α-defensins. We therefore outline differences in antifungal immune defense between humans and mouse strains, which facilitates a more accurate interpretation of in vivo results.

  • 183.
    Erttmann, Saskia F.
    et al.
    Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR). Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS).
    Gekara, Nelson O.
    Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS). Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR). Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, Stockholm, Sweden.
    Hydrogen peroxide release by bacteria suppresses inflammasome-dependent innate immunity2019In: Nature Communications, ISSN 2041-1723, E-ISSN 2041-1723, Vol. 10, article id 3493Article in journal (Refereed)
    Abstract [en]

    Hydrogen peroxide (H2O2) has a major function in host-microbial interactions. Although most studies have focused on the endogenous H2O2 produced by immune cells to kill microbes, bacteria can also produce H2O2. How microbial H2O2 influences the dynamics of host-microbial interactions is unclear. Here we show that H2O2 released by Streptococcus pneumoniae inhibits inflammasomes, key components of the innate immune system, contributing to the pathogen colonization of the host. We also show that the oral commensal H2O2-producing bacteria Streptococcus oralis can block inflammasome activation. This study uncovers an unexpected role of H2O2 in immune suppression and demonstrates how, through this mechanism, bacteria might restrain the immune system to co-exist with the host.

  • 184.
    Esberg, Anders
    et al.
    Umeå University, Faculty of Science and Technology, Department of Molecular Biology (Faculty of Science and Technology).
    Moqtaderi, Zarmik
    Fan, Xiaochun
    Lu, Jian
    Umeå University, Faculty of Science and Technology, Department of Molecular Biology (Faculty of Science and Technology).
    Struhl, Kevin
    Byström, Anders
    Umeå University, Faculty of Science and Technology, Department of Molecular Biology (Faculty of Science and Technology).
    Iwr1 protein is important for preinitiation complex formation by all three nuclear RNA polymerases in Saccharomyces cerevisiae2011In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 6, no 6, p. e20829-Article in journal (Refereed)
    Abstract [en]

    BACKGROUND: Iwr1, a protein conserved throughout eukaryotes, was originally identified by its physical interaction with RNA polymerase (Pol) II.

    PRINCIPAL FINDINGS: Here, we identify Iwr1 in a genetic screen designed to uncover proteins involved in Pol III transcription in S. cerevisiae. Iwr1 is important for Pol III transcription, because an iwr1 mutant strain shows reduced association of TBP and Pol III at Pol III promoters, a decreased rate of Pol III transcription, and lower steady-state levels of Pol III transcripts. Interestingly, an iwr1 mutant strain also displays reduced association of TBP to Pol I-transcribed genes and of both TBP and Pol II to Pol II-transcribed promoters. Despite this, rRNA and mRNA levels are virtually unaffected, suggesting a post-transcriptional mechanism compensating for the occupancy defect.

    CONCLUSIONS: Thus, Iwr1 plays an important role in preinitiation complex formation by all three nuclear RNA polymerases.

  • 185.
    Espanha, Maria
    et al.
    Faculty of Human Kinetics, Technical University of Lisboa, Estrada da Costa, Cruz Quehrada, Lishoa, Portugal.
    Lammi, Pirkko
    Department of Anatomy, University of Kuopio, Kuopio, Finland.
    Hyttinen, Mika
    Department of Anatomy, University of Kuopio, Kuopio, Finland.
    Lammi, Mikko
    Department of Anatomy, University of Kuopio, Kuopio, Finland.
    Helminen, Heikki
    Department of Anatomy, University of Kuopio, Kuopio, Finland.
    Extracellular matrix composition of full-thickness defect repair tissue is little influenced by exercise in rat articular cartilage.2001In: Connective Tissue Research, ISSN 0300-8207, E-ISSN 1607-8438, Vol. 42, no 2, p. 97-109, article id 11718471Article in journal (Refereed)
    Abstract [en]

    Full-thickness articular cartilage defects in the femoral condyles of adult rats were examined four and eight weeks after injury. Quantitative polarized light microscopic analysis showed that birefringence of the tissue in the central repair area increased more in rats exercised on a treadmill. Glycosaminoglycan content in the repair tissue was also higher than in the intermittent active motion group at four weeks after injury, but by eight weeks the levels were similar in both groups. No normal-looking articular cartilage was formed in the lesions, and only in one animal type II collagen was observed in the superficial zone of repair tissue. No 3B3(-) antigenicity of the proteoglycans was seen during repair. In conclusion, exercise minimally modified the repair of full-thickness articular cartilage defects in adult rats. The repair in the exercised group may occur slightly faster in the early stages but no difference was seen at the eight week time interval between the exercised and the intermittently active group.

  • 186. Fabrik, Ivo
    et al.
    Härtlova, Anetta
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine). Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS).
    Rehulka, Pavel
    Stulik, Jiri
    Serving the new masters: dendritic cells as hosts for stealth intracellular bacteria2013In: Cellular Microbiology, ISSN 1462-5814, E-ISSN 1462-5822, Vol. 15, no 9, p. 1473-1483Article in journal (Refereed)
  • 187. Fadeev, Andrey
    et al.
    Mendoza-Garcia, Patricia
    Umeå University, Faculty of Science and Technology, Department of Molecular Biology (Faculty of Science and Technology).
    Irion, Uwe
    Guan, Jikui
    Pfeifer, Kathrin
    Wiessner, Stephanie
    Serluca, Fabrizio
    Singh, Ajeet Pratap
    Nuesslein-Volhard, Christiane
    Palmer, Ruth H.
    ALKALs are in vivo ligands for ALK family receptor tyrosine kinases in the neural crest and derived cells2018In: Proceedings of the National Academy of Sciences of the United States of America, ISSN 0027-8424, E-ISSN 1091-6490, Vol. 115, no 4, p. E630-E638Article in journal (Refereed)
    Abstract [en]

    Mutations in anaplastic lymphoma kinase (ALK) are implicated in somatic and familial neuroblastoma, a pediatric tumor of neural crest-derived tissues. Recently, biochemical analyses have identified secreted small ALKAL proteins (FAM150, AUG) as potential ligands for human ALK and the related leukocyte tyrosine kinase (LTK). In the zebrafish Danio rerio, DrLtk, which is similar to human ALK in sequence and domain structure, controls the development of iridophores, neural crest-derived pigment cells. Hence, the zebrafish system allows studying Alk/Ltk and Alkals involvement in neural crest regulation in vivo. Using zebrafish pigment pattern formation, Drosophila eye patterning, and cell culture-based assays, we show that zebrafish Alkals potently activate zebrafish Ltk and human ALK driving downstream signaling events. Overexpression of the three DrAlkals cause ectopic iridophore development, whereas loss-of-function alleles lead to spatially distinct patterns of iridophore loss in zebrafish larvae and adults. alkal loss-of-function triple mutants completely lack iridophores and are larval lethal as is the case for ltk null mutants. Our results provide in vivo evidence of (i) activation of ALK/LTK family receptors by ALKALs and (ii) an involvement of these ligand-receptor complexes in neural crest development.

  • 188. Fagerberg, David
    et al.
    Angström, Jonas
    Halim, Adnan
    Hultberg, Anna
    Rakhimova, Lena
    Umeå University, Faculty of Medicine, Department of Medical Biochemistry and Biophysics.
    Hammarström, Lennart
    Borén, Thomas
    Umeå University, Faculty of Medicine, Department of Medical Biochemistry and Biophysics.
    Teneberg, Susann
    Novel Leb-like Helicobacter pylori-binding glycosphingolipid created by the expression of human alpha-1,3/4-fucosyltransferase in FVB/N mouse stomach.2009In: Glycobiology, ISSN 0959-6658, E-ISSN 1460-2423, Vol. 19, no 2, p. 182-191Article in journal (Refereed)
    Abstract [en]

    The "Le(b) mouse" was established as a model for investigations of the molecular events following Le(b)-mediated adhesion of Helicobacter pylori to the gastric epithelium. By the expression of a human alpha-1,3/4-fucosyltransferase in the gastric pit cell lineage of FVB/N transgenic mice, a production of Le(b) glycoproteins in gastric pit and surface mucous cells was obtained in this "Le(b) mouse," as demonstrated by binding of monoclonal anti-Le(b) antibodies. To explore the effects of the human alpha-1,3/4-fucosyltransferase on glycosphingolipid structures, neutral glycosphingolipids were isolated from stomachs of transgenic alpha-1,3/4-fucosyltransferase-expressing mice. A glycosphingolipid recognized by BabA-expressing H. pylori was isolated and characterized by mass spectrometry and proton NMR as Fuc alpha 2Gal beta 3(Fuc alpha 4)GalNAc beta 4 Gal beta 4 Glc beta 1Cer, i.e., a novel Le(b)-like glycosphingolipid on a ganglio core. In addition, two other novel glycosphingolipids were isolated from the mouse stomach epithelium that were found to be nonbinding with regard to H. pylori. The first was a pentaglycosylceramide, GalNAc beta 3 Gal alpha 3(Fuc alpha 2)Gal beta 4 Glc beta 1Cer, in which the isoglobotetrasaccharide has been combined with Fuc alpha 2 to yield an isoglobotetraosylceramide with an internal blood group B determinant. The second one was an elongated fucosyl-gangliotetraosylceramide, GalNAc beta 3(Fuc alpha 2)Gal beta 3GalNAc beta 4Gal beta 4 Glc beta 1Cer.

  • 189.
    Fahlgren, Anna
    et al.
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine).
    Westermark, Linda
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine). Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS).
    Akopyan, Karen
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine). Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS).
    Fällman, Maria
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine). Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR).
    Cell type-specific effects of Yersinia pseudotuberculosis virulence effectors2009In: Cellular Microbiology, ISSN 1462-5814, E-ISSN 1462-5822, Vol. 11, no 12, p. 1750-1767Article in journal (Refereed)
    Abstract [en]

    One important feature of Yersinia pseudotuberculosis that enables resistance against the host immune defence is delivery of the antiphagocytic effectors YopH and YopE into phagocytic cells. The tyrosine phosphatase YopH influences integrin signalling, and YopE impairs cytoskeletal dynamics by inactivating Rho GTPases. Here, we report the impact of these effectors on internalization by dendritic cells (DCs), which internalize antigens to orchestrate host immune responses. We found that this pathogen resists internalization by DCs via YopE. YopH that is important for blocking phagocytosis by macrophages and neutrophils and which is also present inside the DCs does not contribute to the resistance. However, the YopH targets Fyb and p130Cas show higher expression levels in macrophages than in DCs. Furthermore, live cell microscopy revealed that the cells internalize Y. pseudotuberculosis in different ways: the macrophages utilize a locally restricted receptor-mediated zipper mechanism, whereas DCs utilize macropinocytosis involving constitutive ruffling that randomly catches bacteria into membrane folds. We conclude that YopH impacts early phagocytic signalling from the integrin receptor to which the bacterium binds and that this tight receptor-mediated stimulation is absent in DC macropinocytosis. Inactivation of cytoskeletal dynamics by YopE affects ruffling activity and hence also internalization. The different modes of internalization can be coupled to the major functions of these respective cell types: elimination by phagocytosis and antigen sampling.

  • 190.
    Fallah, Mahsa
    Umeå University, Faculty of Medicine, Department of Medical Biochemistry and Biophysics.
    Plasminogen: a pleiotropic inflammatory regulator in radiation-induced wound formation and wound repair2018Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The plasminogen activator (PA) system plays important roles in many physiological and pathological processes, including inflammation and wound healing. Plasmin, the central component of the PA system, is a broad-spectrum serine protease that is derived from its inactive precursor form, plasminogen. The first aim of this thesis was to study the role of plasminogen in the formation of radiation-induced wounds, which are an inflammatory side effect of radiotherapy. The second aim was to investigate the molecular mechanisms behind the potentiating effect of plasminogen in the healing of radiation-induced wounds. The third aim was to explore the therapeutic potential of plasminogen in the healing of radiation-induced wounds.

    Radiation therapy in cancer patients is often limited by side effects such as radiation-induced skin damage (radiodermatitis). The mechanisms behind the formation of radiodermatitis are not fully elucidated, and there are no effective preventive therapies for clinical use. In this study, we show that irradiation of skin in WT (wild-type) mice induces plasminogen accumulation, which is followed by activation of TGF-β (transforming growth factor-beta) signaling and the development of inflammation that leads to skin damage. However, plasminogen-deficient mice and mice lacking PAs were mostly resistant to radiodermatitis. Moreover, treatment with a plasminogen inhibitor, tranexamic acid, decreases radiodermatitis in WT mice and prevented radiodermatitis in heterozygous mice. Thus, plasmin is required for the formation of radiodermatitis, and inhibition of plasminogen activation might be a novel treatment strategy to reduce or prevent radiodermatitis in patients undergoing radiotherapy.

    Wound healing consists of partially overlapping inflammatory, proliferation, and tissue remodeling phases, and failure to terminate inflammation leads to the formation of chronic wounds. Previous studies by our group have shown that plasminogen is transported to acute wounds by inflammatory cells where it potentiates inflammation and enhances wound healing. Here, we report that plasminogen-deficient mice, which have delayed wound healing, have extensive fibrin and neutrophil depositions in the wounded area long after re-epithelialization, indicating inefficient debridement and chronic inflammation. The delayed formation of granulation tissue suggests that fibroblast function is also impaired in the absence of plasminogen. Therefore, in addition to its role in the activation of inflammation, plasminogen is also crucial for the resolution of inflammation and the activation of the proliferation phase. Importantly, supplementation of plasminogen-deficient mice with human plasminogen leads to a restored healing capacity that is comparable to that in WT mice. Therefore, plasminogen might be an important future therapeutic agent for treatment of wounds.

    In radiation-induced wounds, inflammation often cannot resolve and the wounds become chronic and fibrotic. Currently, there is no gold standard for the treatment of radiation-induced wounds. In this study, we have shown that radiation-induced wounds treated with plasminogen healed faster than placebo-treated wounds, had diminished inflammation and granulation tissue formation, and had enhanced re-epithelialization and collagen maturation. Transcriptome analysis showed that plasminogen has a pleiotropic effect on gene expression during wound healing, influencing the expression of 33 genes out of the 84 genes studied. In particular, plasminogen decreased the expression of 11 pro-inflammatory genes early in the healing process. Later, plasminogen decreased WNT (Wingless/Integrated) and TGF-β signaling, as well as the expression of 5 growth factors and 13 factors involved in granulation tissue formation. From the genes downregulated by plasminogen, 19 genes are known to be involved in fibrosis. These results show that in radiation-induced wounds with excessive inflammation and tissue formation plasminogen is able to direct the healing process to a normal outcome without the risk for developing fibrosis. This makes plasminogen an attractive drug candidate for treating radiodermatitis in cancer patients. Taken together, our results indicate that plasminogen is a pleiotropic inflammatory regulator involved in radiation-induced wound formation as well as in wound repair.

  • 191.
    Fallah, Mahsa
    et al.
    Umeå University, Faculty of Medicine, Department of Medical Biochemistry and Biophysics.
    Shen, Yue
    Umeå University, Faculty of Medicine, Department of Medical Biochemistry and Biophysics.
    Brodén, Jessica
    Bäckman, Assar
    Lundskog, Bertil
    Umeå University, Faculty of Medicine, Department of Medical Biosciences, Pathology.
    Johansson, Mikael
    Umeå University, Faculty of Medicine, Department of Radiation Sciences.
    Blomqvist, Michael
    Umeå University, Faculty of Medicine, Department of Radiation Sciences.
    Liu, Kui
    Wilczynska, Malgorzata
    Umeå University, Faculty of Medicine, Department of Medical Biochemistry and Biophysics.
    Ny, Tor
    Umeå University, Faculty of Medicine, Department of Medical Biochemistry and Biophysics.
    Plasminogen activation is required for the development of radiation-induced dermatitis2018In: Cell Death and Disease, ISSN 2041-4889, E-ISSN 2041-4889, Vol. 9, no 11, article id 1051Article in journal (Refereed)
    Abstract [en]

    Skin damage caused by radiation therapy (radiodermatitis) is a severe side effect of radiotherapy in cancer patients, and there is currently a lack of effective strategies to prevent or treat such skin damage. In this work, we show with several lines of evidence that plasminogen, a pro-inflammatory factor, is key for the development of radiodermatitis. After skin irradiation in wild type (plg+/+) mice, the plasminogen level increased in the radiated area, leading to severe skin damage such as ulcer formation. However, plasminogen-deficient (plg−/−) mice and mice lacking plasminogen activators were mostly resistant to radiodermatitis. Moreover, treatment with a plasminogen inhibitor, tranexamic acid, decreased radiodermatitis in plg+/+ mice and prevented radiodermatitis in plg+/ mice. Together with studies at the molecular level, we report that plasmin is required for the induction of inflammation after irradiation that leads to radiodermatitis, and we propose that inhibition of plasminogen activation can be a novel treatment strategy to reduce and prevent the occurrence of radiodermatitis in patients.

     

     

  • 192. Figueroa, Jonine D.
    et al.
    Ye, Yuanqing
    Siddiq, Afshan
    Garcia-Closas, Montserrat
    Chatterjee, Nilanjan
    Prokunina-Olsson, Ludmila
    Cortessis, Victoria K.
    Kooperberg, Charles
    Cussenot, Olivier
    Benhamou, Simone
    Prescott, Jennifer
    Porru, Stefano
    Dinney, Colin P.
    Malats, Nuria
    Baris, Dalsu
    Purdue, Mark
    Jacobs, Eric J.
    Albanes, Demetrius
    Wang, Zhaoming
    Deng, Xiang
    Chung, Charles C.
    Tang, Wei
    Bueno-De-Mesquita, H. Bas
    Trichopoulos, Dimitrios
    Ljungberg, Börje
    Umeå University, Faculty of Medicine, Department of Surgical and Perioperative Sciences, Urology and Andrology.
    Clavel-Chapelon, Frangoise
    Weiderpass, Elisabete
    Krogh, Vittorio
    Dorronsoro, Miren
    Travis, Ruth
    Tjonneland, Anne
    Brenan, Paul
    Chang-Claude, Jenny
    Riboli, Elio
    Conti, David
    Gago-Dominguez, Manuela
    Stern, Mariana C.
    Pike, Malcolm C.
    Van den Berg, David
    Yuan, Jian-Min
    Hohensee, Chancellor
    Rodabough, Rebecca
    Cancel-Tassin, Geraldine
    Roupret, Morgan
    Comperat, Eva
    Chen, Constance
    De Vivo, Immaculata
    Giovannucci, Edward
    Hunter, David J.
    Kraft, Peter
    Lindstrom, Sara
    Carta, Angela
    Pavanello, Sofia
    Arici, Cecilia
    Mastrangelo, Giuseppe
    Kamat, Ashish M.
    Lerner, Seth P.
    Grossman, H. Barton
    Lin, Jie
    Gu, Jian
    Pu, Xia
    Hutchinson, Amy
    Burdette, Laurie
    Wheeler, William
    Kogevinas, Manolis
    Tardon, Adonina
    Serra, Consol
    Carrato, Alfredo
    Garcia-Closas, Reina
    Lloreta, Josep
    Schwenn, Molly
    Karagas, Margaret R.
    Johnson, Alison
    Schned, Alan
    Armenti, Karla R.
    Hosain, G. M.
    Andriole, Gerald, Jr.
    Grubb, Robert, III
    Black, Amanda
    Diver, W. Ryan
    Gapstur, Susan M.
    Weinstein, Stephanie J.
    Virtamo, Jarmo
    Haiman, Chris A.
    Landi, Maria T.
    Caporaso, Neil
    Fraumeni, Joseph F., Jr.
    Vineis, Paolo
    Wu, Xifeng
    Silverman, Debra T.
    Chanock, Stephen
    Rothman, Nathaniel
    Genome-wide association study identifies multiple loci associated with bladder cancer risk2014In: Human Molecular Genetics, ISSN 0964-6906, E-ISSN 1460-2083, Vol. 23, no 5, p. 1387-1398Article in journal (Refereed)
    Abstract [en]

    andidate gene and genome-wide association studies (GWAS) have identified 11 independent susceptibility loci associated with bladder cancer risk. To discover additional risk variants, we conducted a new GWAS of 2422 bladder cancer cases and 5751 controls, followed by a meta-analysis with two independently published bladder cancer GWAS, resulting in a combined analysis of 6911 cases and 11 814 controls of European descent. TaqMan genotyping of 13 promising single nucleotide polymorphisms with P < 1 × 10−5 was pursued in a follow-up set of 801 cases and 1307 controls. Two new loci achieved genome-wide statistical significance: rs10936599 on 3q26.2 (P = 4.53 × 10−9) and rs907611 on 11p15.5 (P = 4.11 × 10−8). Two notable loci were also identified that approached genome-wide statistical significance: rs6104690 on 20p12.2 (P = 7.13 × 10−7) and rs4510656 on 6p22.3 (P = 6.98 × 10−7); these require further studies for confirmation. In conclusion, our study has identified new susceptibility alleles for bladder cancer risk that require fine-mapping and laboratory investigation, which could further understanding into the biological underpinnings of bladder carcinogenesis.

  • 193.
    Fischer, M Dominik
    et al.
    University of Pennsylvania School of Medicine.
    Gorospe, J Rafael
    George Washington University, Washington.
    Felder, Edward
    University of Pennsylvania School of Medicine, Philadelphia.
    Bogdanovich, Sasha
    University of Pennsylvania School of Medicine.
    Pedrosa-Domellöf, Fatima
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Anatomy.
    Ahima, Rexford S
    University of Pennsylvania School of Medicine, Philadelphia.
    Rubinstein, Neal A
    University of Pennsylvania School of Medicine, Philadelphia.
    Hoffman, Eric P
    George Washington University, Washington.
    Khurana, Tejvir S
    University of Pennsylvania School of Medicine.
    Expression profiling reveals metabolic and structural components of extraocular muscles2002In: Physiological Genomics, ISSN 1094-8341, E-ISSN 1531-2267, Vol. 9, no 2, p. 71-84Article in journal (Refereed)
    Abstract [en]

    The extraocular muscles (EOM) are anatomically and physiologically distinct from other skeletal muscles. EOM are preferentially affected in mitochondrial myopathies, but spared in Duchenne's muscular dystrophy. The anatomical and pathophysiological properties of EOM have been attributed to their unique molecular makeup: an allotype. We used expression profiling to define molecular features of the EOM allotype. We found 346 differentially expressed genes in rat EOM compared with tibialis anterior, based on a twofold difference cutoff. Genes required for efficient, fatigue-resistant, oxidative metabolism were increased in EOM, whereas genes for glycogen metabolism were decreased. EOM also showed increased expression of genes related to structural components of EOM such as vessels, nerves, mitochondria, and neuromuscular junctions. Additionally, genes related to specialized functional roles of EOM such as the embryonic and EOM-specific myosin heavy chains and genes for muscle growth, development, and/or regeneration were increased. The EOM expression profile was validated using biochemical, structural, and molecular methods. Characterization of the EOM expression profile begins to define gene transcription patterns associated with the unique anatomical, metabolic, and pathophysiological properties of EOM.

  • 194.
    Flanagan, J Randall
    et al.
    Queen's University, Kingston, Ontario.
    Vetter, Philipp
    University College London, Queen Square, London.
    Johansson, Roland S
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Physiology.
    Wolpert, Daniel M
    University College London, Queen Square, London.
    Prediction precedes control in motor learning2003In: Current Biology, ISSN 0960-9822, E-ISSN 1879-0445, Vol. 13, no 2, p. 146-150, Article Number: PII S0960-9822(03)00007-1Article in journal (Refereed)
    Abstract [en]

    Skilled motor behavior relies on the brain learning both to control the body and predict the consequences of this control. Prediction turns motor commands into expected sensory consequences, whereas control turns desired consequences into motor commands. To capture this symmetry, the neural processes underlying prediction and control are termed the forward and inverse internal models, respectively. Here, we investigate how these two fundamental processes are related during motor learning. We used an object manipulation task in which subjects learned to move a hand-held object with novel dynamic properties along a prescribed path. We independently and simultaneously measured subjects' ability to control their actions and to predict their consequences. We found different time courses for predictor and controller learning, with prediction being learned far more rapidly than control. In early stages of manipulating the object, subjects could predict the consequences of their actions, as measured by the grip force they used to grasp the object, but could not generate appropriate actions for control, as measured by their hand trajectory. As predicted by several recent theoretical models of sensorimotor control, our results indicate that people can learn to predict the consequences of their actions before they can learn to control their actions.

  • 195.
    Florea, Cristina
    et al.
    "Politehnica” University of Timisoara, Mechanical Engineering Faculty, Mechatronics Department, Timisoara, Romania; University of Eastern Finland, Department of Applied Physics, Kuopio, Finland.
    Jakorinne, Asmo
    Savonia University of Applied Sciences, School of Engineering and Technology, Kuopio, Finland.
    Lammi, Mikko
    University of Eastern Finland, Department of Biosciences, Kuopio, Finland.
    Davidescu, Arjana
    “Politehnica” University of Timisoara, Mechanical Engineering Faculty, Mechatronics Department, Timisoara, Romania.
    Korhonen, Rami
    University of Eastern Finland, Department of Applied Physics, Kuopio, Finland.
    Determination of mechanical properties of chondrocytes in articular cartilage using atomic force microscopy2014In: Solid State Phenomena, ISSN 1012-0394, E-ISSN 1662-9779, Vol. 216, p. 134-139Article in journal (Refereed)
    Abstract [en]

    Atomic Force Microscopy (AFM) based nanoindentation is a widely used technique for measuring mechanical properties of living cells, providing information for understanding their mechanobiological behavior. However, very local properties of cell surfaces have not been characterized earlier. The goal of this study was to develop an AFM-based technique to determine local elastic properties of bovine articular chondrocytes. The Youngs modulus of chondrocytes was 19.3 ± 5.6 kPa for spread cells and 10 ± 4.1 kPa for the round cells. The results were compared to previous studies in which different techniques were used to obtain more global properties of chondrocytes. Our findings suggest that using nanosized AFM tips, the very local cell properties can be measured.

  • 196.
    Florea, Cristina
    et al.
    Department of Applied Physics, University of Eastern Finland, Kuopio, Finland.
    Tanska, Petri
    Department of Applied Physics, University of Eastern Finland, Kuopio, Finland.
    Mononen, Mika
    Department of Applied Physics, University of Eastern Finland, Kuopio, Finland.
    Qu, Chengjuan
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB).
    Lammi, Mikko
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB). School of Public Health, Health Science Center of Xi’an Jiaotong University, Key Laboratory of Trace Elements and Endemic Diseases, National Health and Family Planning Commission, Xi’an, China.
    Laasanen, Mikko
    School of Engineering and Technology, Savonia University of Applied Sciences, Kuopio, Finland.
    Korhonen, Rami
    Department of Applied Physics, University of Eastern Finland, Kuopio, Finland; Diagnostic Imaging Center, Kuopio University Hospital, Kuopio, Finland.
    A combined experimental atomic force microscopy-based nanoindentation and computational modeling approach to unravel the key contributors to the time-dependent mechanical behavior of single cells2017In: Biomechanics and Modeling in Mechanobiology, ISSN 1617-7959, E-ISSN 1617-7940, Vol. 16, no 1, p. 297-311, article id 27554263Article in journal (Refereed)
    Abstract [en]

    Cellular responses to mechanical stimuli are influenced by the mechanical properties of cells and the surrounding tissue matrix. Cells exhibit viscoelastic behavior in response to an applied stress. This has been attributed to fluid flow-dependent and flow-independent mechanisms. However, the particular mechanism that controls the local time-dependent behavior of cells is unknown. Here, a combined approach of experimental AFM nanoindentation with computational modeling is proposed, taking into account complex material behavior. Three constitutive models (porohyperelastic, viscohyperelastic, poroviscohyperelastic) in tandem with optimization algorithms were employed to capture the experimental stress relaxation data of chondrocytes at 5 % strain. The poroviscohyperelastic models with and without fluid flow allowed through the cell membrane provided excellent description of the experimental time-dependent cell responses (normalized mean squared error (NMSE) of 0.003 between the model and experiments). The viscohyperelastic model without fluid could not follow the entire experimental data that well (NMSE = 0.005), while the porohyperelastic model could not capture it at all (NMSE = 0.383). We also show by parametric analysis that the fluid flow has a small, but essential effect on the loading phase and short-term cell relaxation response, while the solid viscoelasticity controls the longer-term responses. We suggest that the local time-dependent cell mechanical response is determined by the combined effects of intrinsic viscoelasticity of the cytoskeleton and fluid flow redistribution in the cells, although the contribution of fluid flow is smaller when using a nanosized probe and moderate indentation rate. The present approach provides new insights into viscoelastic responses of chondrocytes, important for further understanding cell mechanobiological mechanisms in health and disease.

  • 197.
    Fong, Gloria
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB).
    Influence of neuromodulators and mechanical loading on pathological cell and tissue characteristics in tendinosis2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Background: Tendinosis is a painful chronic, degenerative condition characterized by objective changes in the tissue structure of a tendon. Hallmark features in tendinosis tendons include increased number of cells (hypercellularity), extracellular matrix (ECM) degradation and disorganized collagen. The progression of these pathological changes seen in tendinosis is neither well characterized nor fully understood.

    Studies have suggested that there are biochemical and mechanical elements involved in tendinosis. From a biochemical perspective, studies have shown that the tendon cells, tenocytes, produce a number of neuronal signal substances/neuromodulators, such as substance P (SP) and acetylcholine (ACh), traditionally thought to be confined to the nervous system. Furthermore, it has been shown that the expression of these neuromodulators is elevated in tendinosis tendons as compared to normal healthy tendons. Interestingly, studies on other tissue types have revealed that both SP and ACh can induce tissue changes seen in tendinosis, such as hypercellularity and collagen disorganization. From a mechanical angle, it has been suggested that overload of tendons, including extensive strain on the primary tendon cells (tenocytes), causes the degenerative processes associated with tendinosis. In vivo studies have shown that in overloaded tendons, the presence of neuromodulators is elevated, not least SP, which also precedes the development of the tissue changes seen in tendinosis. This further supports the importance of combining biochemical factors and mechanical factors in the pathogenesis of tendinosis.

    Hypotheses: In this thesis project, we hypothesize: 1) that neuromodulators, such as SP and ACh when stimulating their preferred receptors, the neurokinin 1 (NK-1 R) and muscarinic receptors (mAChRs), respectively, can cause increased tenocyte proliferation; 2) that the effects of SP and ACh on tenocyte proliferation converge mechanistically via a shared signalling pathway; 3) that mechanical loading of tenocytes results in increased production of SP by the tenocytes; and 4) that SP enhances collagen remodelling by tenocytes via NK-1 R.

    Model system: In vitro studies offer insight into the function of healthy tendon matrix and the etiology of tendinopathy. Using a cell culture model of human primary tendon cells, highly controlled experiments were performed in this thesis project to study a subset of biological and mechanical parameters that are implicated in tendinosis. The FlexCell® Tension System was used to study the influence of mechanical loading on tenocytes. As well, a collagen gel contraction assay was used to examine the intrinsic ability of tenocytes to reorganise type I collagen matrices under the influence of the neuromodulator SP.

    Results: The studies showed that exogenous administration of SP and ACh results in increased tenocyte proliferation that is mediated via activation of the ERK1/2 mitogenic pathway when the preferred receptors of SP and ACh, the NK-1 R and mAChRs, respectively, are stimulated. Furthermore, the studies resulted in the novel finding that SP and ACh both converge mechanistically via transforming growth factor (TGF)-β1 and that a negative feedback mechanism is present in which TGF-β1 downregulates the expression of mAChRs and NK-1 R. The studies also showed that SP can increase collagen remodelling and upregulate expression of genes related to tendinosis. Finally, it was established that tenocytes are mechanoresponsive by showing that cyclic mechanical loading increases the expression of SP by human tenocytes.

    Conclusions: This thesis work concludes that stimulation of NK-1 R and mAChRs results in proliferation of human tenocytes, which both involve the ERK1/2 signalling pathway. It also shows that SP and ACh converge mechanistically via TGF-β1 in their contribution to tenocyte proliferation. The role of hypercellularity in tendinosis tissue is unknown. Possibly, it has different roles at different stages of the disease. The findings also show that SP increases collagen remodelling, suggesting that increased SP not only results in hypercellularity but also contributes to the collagen morphology in tendinosis.

  • 198.
    Fong, Gloria
    et al.
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Anatomy. Centre for Hip Health and Mobility, Vancouver Coastal Health Research Institute, Vancouver, BC, Canada.
    Backman, Ludvig J.
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Anatomy.
    Alfredson, Håkan
    Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation, Sports medicine.
    Scott, Alex
    Centre for Hip Health and Mobility, Vancouver Coastal Health Research Institute, Vancouver, BC, Canada.
    Danielson, Patrik
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Anatomy. Umeå University, Faculty of Medicine, Department of Clinical Sciences, Ophthalmology.
    The Effects of Substance P and Acetylcholine on Human Tenocyte Proliferation Converge Mechanistically via TGF-β12017In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 12, no 3, article id e0174101Article in journal (Refereed)
    Abstract [en]

    Previous in vitro studies on human tendon cells (tenocytes) have demonstrated that the exogenous administration of substance P (SP) and acetylcholine (ACh) independently result in tenocyte proliferation, which is a prominent feature of tendinosis. Interestingly, the possible link between SP and ACh has not yet been explored in human tenocytes. Recent studies in other cell types demonstrate that both SP and ACh independently upregulate TGF-β1 expression via their respective receptors, the neurokinin 1 receptor (NK-1R) and muscarinic ACh receptors (mAChRs). Furthermore, TGF-β1 has been shown to downregulate NK-1R expression in human keratocytes. The aim of this study was to examine if TGF-β1 is the intermediary player involved in mediating the proliferative pathway shared by SP and ACh in human tenocytes. The results showed that exogenous administration of SP and ACh both caused significant upregulation of TGF-β1 at the mRNA and protein levels. Exposing cells to TGF-β1 resulted in increased cell viability of tenocytes, which was blocked in the presence of the TGFβRI/II kinase inhibitor. In addition, the proliferative effects of SP and ACh on tenocytes were reduced by the TGFβRI/II kinase inhibitor; this supports the hypothesis that the proliferative effects of these signal substances are mediated via the TGF-β axis. Furthermore, exogenous TGF-β1 downregulated NK-1R and mAChRs expression at both the mRNA and protein levels, and these effects were negated by simultaneous exposure to the TGFβRI/II kinase inhibitor, suggesting a negative feedback loop. In conclusion, the results indicate that TGF-β1 is the intermediary player through which the proliferative actions of both SP and ACh converge mechanistically.

  • 199.
    Forsgren, Stina
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine).
    Mechanisms of lymphocyte selection in physiology and autoimmune pathology1991Doctoral thesis, comprehensive summary (Other academic)
  • 200.
    Francis, Matthew
    Umeå University, Faculty of Science and Technology, Department of Molecular Biology (Faculty of Science and Technology). Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR).
    The pathogenic Yersiniae: advances in the understanding of physiology and virulence2013In: Frontiers in Cellular and Infection Microbiology, ISSN 2235-2988, Vol. 3, no 51, p. 2p. 1-2Article, review/survey (Refereed)
1234567 151 - 200 of 881
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