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  • 51.
    Grankvist, Kjell
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Histology and Cell Biology.
    Mechanisms of alloxan diabetogenicity1981Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Suspensions of pancreatic islet cells from ob/ob-mice were incubated with Trypan Blue. Microscope photometry showed that apparently viable cells excluded the dye completely, whereas the nuclei of non-viable cells accumulated Trypan Blue by a saturable process. Alloxan rapidly increased the permeability of the plasma membrane in mouse 3-cells; the exclusion of Trypan Blue is a valid and useful measure of islet cell viability following alloxan exposure.

    The diabetogenic action of alloxan may be mediated by hydroxyl radicals. In several biological systems hydroxyl radicals are formed by an iron-catalyzed reaction between superoxide anion radicals and hydrogen peroxide. To test whether this applies to alloxan diabetogenicity, the effects of superoxide dismutase, catalase, scavengers of hydroxyl radicals, and metal ion chelators were tested (a) in a cell-free radical-generating system and (b) on islets and islet-cells exposed to alloxan In vitro. The effect of longtime-circulating superoxide dismutase injected prior to alloxan was tested on mice in vivo.

    Luminol chemiluminescence was used to monitor alloxan-dependent radical production. Accumulation of 8^Rb+ and exclusion of Trypan Blue were used as cell viability criteria in isolated mouse islets and islet-cells. Blood glucose was determined to monitor the development of diabetes in living animals.

    Superoxide dismutase, catalase, scavengers of hydroxyl radicals, and metal ion chelators inhibited the alloxan-dependent chemiluminescence and decreased the toxic effects on Rb+ accumulation or Trypan Blue exclusion in islets and islet-cells. Superoxide dismutase, linked to polyethylene glycol and injected 12 hours before alloxan, largely prevented the development of alloxan diabetes.

    Alloxan toxicity _in vitro and in vivo seems to depend on the formation of superoxide radicals and hydrogen peroxide which in turn form the noxious hydroxyl radical via an iron-catalyzed Haber-Weiss reaction.

    As free radicals and hydrogen peroxide can be formed by other chemicals and during inflammation, and inflammation may accompany the outbreak of human diabetes, studies on the beneficiary effects of superoxide dismutase and other scavengers of free radicals in other forms of diabetes seem warranted.

  • 52.
    Grebe, Markus
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    Out of the shade and into the light2011In: Nature Cell Biology, ISSN 1465-7392, E-ISSN 1476-4679, Vol. 13, no 4, p. 347-349Article in journal (Refereed)
    Abstract [en]

    Plants reach for the sun by avoiding the shade and by directly growing towards the light. Two studies now suggest that the polar relocation of PIN3, a transporter directing the flow of the plant hormone auxin, drives both growth processes. PIN3 repolarization occurs downstream of shade perception through phytochrome photoreceptors, whereas blue light perceived by phototropin initiates polar recycling of PIN3 and growth towards the light.

  • 53.
    Grebe, Markus
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    Plant biology: Unveiling the Casparian strip.2011In: Nature, ISSN 1476-4687, Vol. 473, no 7347, p. 294-5Article in journal (Refereed)
  • 54.
    Hall, Michael
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Wagner, Raik
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Lam, Xuan Tam
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Funk, Christiane
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Persson, Karina
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    The HhoA protease from Synechocystis sp. PCC 6803: novel insights into structure and activity regulation2017In: Journal of Structural Biology, ISSN 1047-8477, E-ISSN 1095-8657, Vol. 198, no 3, p. 147-153Article in journal (Refereed)
    Abstract [en]

    Proteases play a vital role in the removal of proteins, which become damaged due to temperature or oxidative stress. Important to this process in the cyanobacterium Synechocystis sp. PCC6803 is the family of Deg/HtrA proteases; HhoA (sll1679), HhoB (sll1427) and HtrA (slr1204). While previous studies have elucidated the structures of Deg/HtrA proteases from Escherichia coli and from the chloroplast of the higher plant Arabidopsis thaliana, no structural data have been available for any Deg/HtrA protease from cyanobacteria, the evolutionary ancestor of the chloroplast. To gain a deeper insight into the molecular mechanisms and regulation of these proteins we have solved the structure of the Synechocystis HhoA protease in complex with a co-purified peptide by X-ray crystallography. HhoA assembles into stable trimers, mediated by its protease domain and further into a cage-like hexamer by a novel interaction between the PDZ domains of opposing trimers. Each PDZ domain contains two loops for PDZ-PDZ formation: interaction clamp one and two (IC1, IC2). IC1 interacts with IC2 on the opposing PDZ domain and vice versa. Our structure shows a peptide bound to a conserved groove on the PDZ domain and the properties of this pocket suggest that it binds substrate proteins as well as the neo C-termini of cleaved substrates. In agreement with previous studies showing the proteolytic activity of HhoA to be activated by Ca2+ or Mg2+, binding of divalent metal ions to the central channel of the trimer by the L1 activation loop was observed.

  • 55. Hartmann, Laura
    et al.
    Pedrotti, Lorenzo
    Weiste, Christoph
    Fekete, Agnes
    Schierstaedt, Jasper
    Göttler, Jasmin
    Kempa, Stefan
    Krischke, Markus
    Dietrich, Katrin
    Mueller, Martin J
    Vicente-Carbajosa, Jesus
    Hanson, Johannes
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC). Department of Molecular Plant Physiology, Utrecht University, The Netherlands .
    Dröge-Laser, Wolfgang
    Crosstalk between Two bZIP Signaling Pathways Orchestrates Salt-Induced Metabolic Reprogramming in Arabidopsis Roots2015In: The Plant Cell, ISSN 1040-4651, E-ISSN 1532-298X, Vol. 27, no 8, p. 2244-2260Article in journal (Refereed)
    Abstract [en]

    Soil salinity increasingly causes crop losses worldwide. Although roots are the primary targets of salt stress, the signaling networks that facilitate metabolic reprogramming to induce stress tolerance are less understood than those in leaves. Here, a combination of transcriptomic and metabolic approaches was performed in salt-treated Arabidopsis thaliana roots, which revealed that the group S1 basic leucine zipper transcription factors bZIP1 and bZIP53 reprogram primary C- and N-metabolism. In particular, gluconeogenesis and amino acid catabolism are affected by these transcription factors. Importantly, bZIP1 expression reflects cellular stress and energy status in roots. In addition to the well-described abiotic stress response pathway initiated by the hormone abscisic acid (ABA) and executed by SnRK2 (Snf1-RELATED-PROTEIN-KINASE2) and AREB-like bZIP factors, we identify a structurally related ABA-independent signaling module consisting of SnRK1s and S1 bZIPs. Crosstalk between these signaling pathways recruits particular bZIP factor combinations to establish at least four distinct gene expression patterns. Understanding this signaling network provides a framework for securing future crop productivity.

  • 56. He, Hanzi
    et al.
    Willems, Leo
    Batushansky, Albert
    Fait, Aaron
    Hanson, Johannes
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC). Department of Molecular Plant Physiology, Utrecht University, NL-3584 CH Utrecht, The Netherlands.
    Nijveen, Harm
    Hilhorst, Henk W M
    Bentsink, Leónie
    Effects of Parental Temperature and Nitrate on Seed Performance are Reflected by Partly Overlapping Genetic and Metabolic Pathways2016In: Plant and Cell Physiology, ISSN 0032-0781, E-ISSN 1471-9053, Vol. 57, no 3, p. 473-487Article in journal (Refereed)
    Abstract [en]

    Seed performance is affected by the seed maturation environment and previously, we have shown that temperature, nitrate and light intensity were the most influential environmental factors affecting seed performance. Seeds developed in these environments were selected to assess the underlying metabolic pathways, using a combination of transcriptomics and metabolomics. These analyses revealed that the effects of the temperature and nitrate parental environments were reflected by partly overlapping genetic and metabolic networks, as indicated by similar changes in metabolites and transcripts expression levels. Nitrogen-metabolism related metabolites (asparagine, GABA and allantoin) were significantly decreased in both low temperature (15°C) and low nitrate (N0) maturation environments. Correspondingly, nitrogen-metabolism genes (ALLANTOINASE, NITRATE REDUCTASE 1, NITRITE REDUCTASE 1 and NITRILASE 4) were differentially regulated in the low temperature and nitrate maturation environments, as compared with control conditions. High light intensity during seed maturation increased galactinol content, and displayed a high correlation with seed longevity. Low light had a genotype-specific effect on cell surface encoding genes in the DELAY OF GERMINATION 6-Near Isogenic Line (NILDOG6). Overall, the integration of phenotypes, metabolites and transcripts led to new insights in the regulation of seed performance.

  • 57.
    Hemmingsson, Oskar
    et al.
    Umeå University, Faculty of Medicine, Department of Surgical and Perioperative Sciences, Surgery.
    Kao, Gautam
    Umeå University, Faculty of Medicine, Department of Surgical and Perioperative Sciences, Surgery.
    Still, Maria
    Umeå University, Faculty of Medicine, Department of Surgical and Perioperative Sciences, Surgery.
    Naredi, Peter
    Umeå University, Faculty of Medicine, Department of Surgical and Perioperative Sciences, Surgery.
    ASNA-1 activity modulates sensitivity to cisplatin2010In: Cancer Research, ISSN 0008-5472, E-ISSN 1538-7445, Vol. 70, no 24, p. 10321-10328Article in journal (Refereed)
    Abstract [en]

    Cancer can be cured by platinum based chemotherapy but resistance is a major cause of treatment failure. Here we present the nematode Caenorhabditis elegans as a model to study interactions between the platinum drug cisplatin and signaling pathways in vivo. Null mutations in a single gene, asna-1, makes worms hypersensitive to cisplatin. The metalloregulated ATPase ASNA-1 promotes insulin secretion and membrane insertion of tail-anchored proteins. Using structural data from ASNA-1 homologs, we identify specific ASNA-1 mutants that are sensitive to cisplatin while still able to promote insulin signaling. Mutational analysis reveals that hypersensitivity of ASNA-1 mutants to cisplatin remains in absence of CEP-1/p53 or apoptosis. Human ASNA1 can substitute for the worm gene, indicating a conserved function. Cisplatin sensitivity is not affected by decreased insulin signaling in wild type nematodes or restored insulin signaling in asna-1 mutants. These findings provide a functional insight into ASNA-1, demonstrate that C. elegans can be used to characterize cisplatin resistance mechanisms and propose that rationally designed drugs against ASNA-1 can sensitize cancer cells to cisplatin.

  • 58. Hillier, Charles
    et al.
    Pardo, Mercedes
    Yu, Lu
    Bushell, Ellen
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine). Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS).
    Sanderson, Theo
    Metcalf, Tom
    Herd, Colin
    Anar, Burcu
    Rayner, Julian C.
    Billker, Oliver
    Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS). Umeå University, Faculty of Science and Technology, Department of Molecular Biology (Faculty of Science and Technology).
    Choudhary, Jyoti S.
    Landscape of the Plasmodium Interactome Reveals Both Conserved and Species-Specific Functionality2019In: Cell reports, ISSN 2211-1247, E-ISSN 2211-1247, Vol. 28, no 6, p. 1635-1647Article in journal (Refereed)
    Abstract [en]

    Malaria represents a major global health issue, and the identification of new intervention targets remains an urgent priority. This search is hampered by more than one-third of the genes of malaria-causing Plasmodium parasites being uncharacterized. We report a large-scale protein interaction network in Plasmodium schizonts, generated by combining blue native-polyacrylamide electrophoresis with quantitative mass spectrometry and machine learning. This integrative approach, spanning 3 species, identifies > 20,000 putative protein interactions, organized into 600 protein clusters. We validate selected interactions, assigning functions in chromatin regulation to previously unannotated proteins and suggesting a role for an EELM2 domain-containing protein and a putative microrchidia protein as mechanistic links between AP2-domain transcription factors and epigenetic regulation. Our interactome represents a high-confidence map of the native organization of core cellular processes in Plasmodium parasites. The network reveals putative functions for uncharacterized proteins, provides mechanistic and structural insight, and uncovers potential alternative therapeutic targets.

  • 59. Hua, Kuo-Tai
    et al.
    Tan, Ching-Ting
    Johansson, Gunnar
    Graduate Institute of Toxicology, National Taiwan University College of Medicine, Taipei 100, Taiwan.
    Lee, Jang-Ming
    Yang, Pei-Wen
    Lu, Hsin-Yi
    Chen, Chi-Kuan
    Su, Jen-Liang
    Chen, Poshen B
    Wu, Yu-Ling
    Chi, Chia-Chun
    Kao, Hsin-Jung
    Shih, Hou-Jung
    Chen, Min-Wei
    Chien, Ming-Hsien
    Chen, Pai-Sheng
    Lee, Wei-Jiunn
    Cheng, Tsu-Yao
    Rosenberger, George
    Chai, Chee-Yin
    Yang, Chih-Jen
    Huang, Ming-Shyan
    Lai, Tsung-Ching
    Chou, Teh-Ying
    Hsiao, Michael
    Kuo, Min-Liang
    N-α-acetyltransferase 10 protein suppresses cancer cell metastasis by binding PIX proteins and inhibiting Cdc42/Rac1 activity2011In: Cancer Cell, ISSN 1535-6108, E-ISSN 1878-3686, Vol. 19, no 2, p. 218-231Article in journal (Refereed)
    Abstract [en]

    N-α-acetyltransferase 10 protein, Naa10p, is an N-acetyltransferase known to be involved in cell cycle control. We found that Naa10p was expressed lower in varieties of malignancies with lymph node metastasis compared with non-lymph node metastasis. Higher Naa10p expression correlates the survival of lung cancer patients. Naa10p significantly suppressed migration, tumor growth, and metastasis independent of its enzymatic activity. Instead, Naa10p binds to the GIT-binding domain of PIX, thereby preventing the formation of the GIT-PIX-Paxillin complex, resulting in reduced intrinsic Cdc42/Rac1 activity and decreased cell migration. Forced expression of PIX in Naa10-transfected tumor cells restored the migration and metastasis ability. We suggest that Naa10p functions as a tumor metastasis suppressor by disrupting the migratory complex, PIX-GIT- Paxillin, in cancer cells.

  • 60.
    Huch, Susanne
    et al.
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine).
    Müller, Maren
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine).
    Muppavarapu, Mridula
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine).
    Gommlich, Jessie
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine).
    Balagopal, Vidya
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine).
    Nissan, Tracy
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine).
    The decapping activator Edc3 and the Q/N-rich domain of Lsm4 function together to enhance mRNA stability and alter mRNA decay pathway dependence in Saccharomyces cerevisiae2016In: Biology Open, ISSN 2046-6390, Vol. 5, no 10, p. 1388-1399Article in journal (Refereed)
    Abstract [en]

    The rate and regulation of mRNA decay are major elements in the proper control of gene expression. Edc3 and Lsm4 are two decapping activator proteins that have previously been shown to function in the assembly of RNA granules termed P bodies. Here, we show that deletion of edc3, when combined with a removal of the glutamine/asparagine rich region of Lsm4 (edc3Δ lsm4ΔC) reduces mRNA stability and alters pathways of mRNA degradation. Multiple tested mRNAs exhibited reduced stability in the edc3Δ lsm4ΔC mutant. The destabilization was linked to an increased dependence on Ccr4-mediated deadenylation and mRNA decapping. Unlike characterized mutations in decapping factors that either are neutral or are able to stabilize mRNA, the combined edc3Δ lsm4ΔC mutant reduced mRNA stability. We characterized the growth and activity of the major mRNA decay systems and translation in double mutant and wild-type yeast. In the edc3Δ lsm4ΔC mutant, we observed alterations in the levels of specific mRNA decay factors as well as nuclear accumulation of the catalytic subunit of the decapping enzyme Dcp2. Hence, we suggest that the effects on mRNA stability in the edc3Δ lsm4ΔC mutant may originate from mRNA decay protein abundance or changes in mRNPs or alternatively may imply a role for P bodies in mRNA stabilization.

  • 61.
    Höglund, Andreas
    et al.
    Umeå University, Faculty of Science and Technology, Department of Molecular Biology (Faculty of Science and Technology).
    Strömvall, Kerstin
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine).
    Plym Forshell, Linus
    Umeå University, Faculty of Science and Technology, Department of Molecular Biology (Faculty of Science and Technology).
    Nilsson, Jonas A
    Umeå University, Faculty of Science and Technology, Department of Molecular Biology (Faculty of Science and Technology).
    Chk2 deficiency in Myc overexpressing lymphoma cells elicits a synergistic lethal response in combination with PARP inhibition.2011In: Cell Cycle, ISSN 1538-4101, E-ISSN 1551-4005, Vol. 10, no 20, p. 3598-3607Article in journal (Refereed)
    Abstract [en]

    Myc is a transcription factor frequently found deregulated in human cancer. The Myc- mediated cellular transformation process is associated with fast proliferative cells and inherent genomic instability, giving rise to malignant, invasive neoplasms with poor prognosis for survival. Transcription-independent functions of Myc include stimulation of replication. Excessive Myc expression stimulates a replication-associated DNA damage response that signal via the phosphoinositide 3-kinase (PI3K) related protein kinases (PIKKs) ATM and ATR. These in turn activate the DNA damage transducers Chk1 and Chk2. Here, we show that Myc can stimulate Chek2 transcript indirectly in vitro, as well as in B cells of !-Myc transgenic mice or in the intestine of ApcMin mice. However, Chk2 is dispensable for Myc’s ability to transform cells in vitro and for the survival of established lymphoma cells from !-Myc transgenic mice. Chk2 deficiency induces polyploidy and slow growth but the cells are viable and protected against DNA damage. However, inhibition of both Chk1/Chk2 with AZD7762 induces cell death and significantly delays disease progression of transplanted lymphoma cells in vivo. DNA damage recruits PARP family members to sites of DNA breaks that in turn facilitate the induction of DNA repair. Strikingly, combining Chk2 and PARP inhibition elicits a synergistic lethal response in the context of Myc overexpression. Our data indicates that only certain types of chemotherapy would give rise to a synergistic lethal response in combination with specific Chk2 inhibitors, which will be important if Chk2 inhibitors enter the clinic.

  • 62. Höög, Johanna L
    et al.
    Huisman, Stephen M
    Sebö-Lemke, Zsofia
    Sandblad, Linda
    European Mol Biol Labs, Cell Biol & Biophys Program, D-69117 Heidelberg, Germany .
    McIntosh, J Richard
    Antony, Claude
    Brunner, Damian
    Electron tomography reveals a flared morphology on growing microtubule ends2011In: Journal of Cell Science, ISSN 0021-9533, E-ISSN 1477-9137, Vol. 124, no Pt 5, p. 693-698Article in journal (Refereed)
    Abstract [en]

    Microtubules (MTs) exhibit dynamic instability, alternating between phases of growth and shortening, mostly at their uncapped plus ends. Based on results from cryo-electron microscopy it was proposed that growing MTs display mainly curved sheets and blunt ends; during depolymerisation curled 'ramshorns' predominate. Observations of MTs in mitotic cells have suggested that the situation in vivo differs from that in vitro, but so far, a clear comparison between in vivo and in vitro results has not been possible because MT end structures could not be correlated directly with the dynamic state of that particular MT. Here we combine light microscopy and electron tomography (ET) to show that growing MT plus ends in the fission yeast Schizosaccharomyces pombe display predominantly a flared morphology. This indicates that MT polymerisation in vivo and in vitro can follow different paths.

  • 63. Igamberdiev, Abir U.
    et al.
    Lernmark, Ulrika
    Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC). Umeå University, Faculty of Science and Technology, Department of Plant Physiology.
    Gardeström, Per
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    Activity of the mitochondrial pyruvate dehydrogenase complex in plants is stimulated in the presence of malate2014In: Mitochondrion (Amsterdam. Print), ISSN 1567-7249, E-ISSN 1872-8278, Vol. 19, no Part B, p. 184-190Article in journal (Refereed)
    Abstract [en]

    The effect of malate on the steady-state activity of the pea (Pisum sativum L.) and barley (Hordeum vulgare L) leaf pyruvate dehydrogenase complex (PDC) has been studied in isolated mitochondria. The addition of malate was found to be stimulatory for the mitochondrial PDC, however there was no stimulation of chloroplast PDC. The stimulation was saturated below 1 mM malate and was apparently related to a partially activated complex, which activity increased in the presence of malate by about twofold. Malate also reversed the reduction of PDC activity in the presence of glycine. Based on the obtained kinetic data, we suggest that the effect of malate is rather not a direct activation of PDC but involves the establishment of NAD-malate dehydrogenase equilibrium, decreasing concentration of NADH and relieving its inhibitory effect of PDC. 

  • 64.
    Johansson, Gunnar
    et al.
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Oncology. Umeå University.
    Mahller, Yonatan Y
    Collins, Margaret H
    Kim, Mi-Ok
    Nobukuni, Takahiro
    Perentesis, John
    Cripe, Timothy P
    Lane, Heidi A
    Kozma, Sara C
    Thomas, George
    Ratner, Nancy
    Effective in vivo targeting of the mammalian target of rapamycin pathway in malignant peripheral nerve sheath tumors.2008In: Molecular Cancer Therapeutics, ISSN 1535-7163, E-ISSN 1538-8514, Vol. 7, no 5, p. 1237-45Article in journal (Refereed)
    Abstract [en]

    Malignant peripheral nerve sheath tumors (MPNST) are chemoresistant sarcomas with poor 5-year survival that arise in patients with neurofibromatosis type 1 (NF1) or sporadically. We tested three drugs for single and combinatorial effects on collected MPNST cell lines and in MPNST xenografts. The mammalian target of rapamycin complex 1 inhibitor RAD001 (Everolimus) decreased growth 19% to 60% after 4 days of treatment in NF1 and sporadic-derived MPNST cell lines. Treatment of subcutaneous sporadic MPNST cell xenografts with RAD001 significantly, but transiently, delayed tumor growth, and decreased vessel permeability within xenografts. RAD001 combined with the epidermal growth factor receptor tyrosine kinase inhibitor erlotinib caused additional inhibitory effects on growth and apoptosis in vitro, and a small but significant additional inhibitory effect on MPNST growth in vivo that were larger than the effects of RAD001 with doxorubicin. RAD001 plus erlotinib, in vitro and in vivo, reduced phosphorylation of AKT and total AKT levels, possibly accounting for their additive effect. The results support the consideration of RAD001 therapy in NF1 patient and sporadic MPNST. The preclinical tests described allow rapid screening strata for drugs that block MPNST growth, prior to tests in more complex models, and should be useful to identify drugs that synergize with RAD001.

  • 65.
    Johansson, Gunnar
    et al.
    Department of Neurology, National Taiwan University Hospital, Taipei, Taiwan .
    Peng, Po-Chun
    Huang, Po-Yuan
    Chien, Hsiung-Fei
    Hua, Kuo-Tai
    Kuo, Min-Liang
    Chen, Chin-Tin
    Lee, Ming-Jen
    Soluble AXL: a possible circulating biomarker for neurofibromatosis type 1 related tumor burden2014In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 9, no 12, article id e115916Article in journal (Refereed)
    Abstract [en]

    Neurofibromatosis type 1 (NF1) is the most common tumor predisposition disorder affecting 1/3500 worldwide. Patients are at risk of developing benign (neurofibromas) and malignant peripheral nerve sheath tumors (MPNST). The AXL receptor tyrosine kinase has been implicated in several kinds of cancers, but so far no studies have investigated the role of AXL in NF1 related tumorigenesis. Recently, the soluble fraction from the extracellular domain of AXL (sAXL) has been found in human plasma, and its level was correlated to poor prognosis in patients with renal cancer. Compared to normal human Schwann cells, a significantly high expression level of AXL was found in three of the four MPNST cell lines and two of the three primary MPNST tissues. Similarly, the level of sAXL in conditioned media corresponded to the protein and mRNA levels of AXL in the MPNST cell lines. Furthermore, in two different human MPNST xenograft models, the human sAXL could be detected in the mouse plasma. Its level was proportionate to the size of the xenograft tumors, while no human sAXL was detect prior to the formation of the tumors. Treatment with a newly developed photodynamic therapy, prevented further tumor growth and resulted in drastically reduced the levels of sAXL compared to that of the control group. Finally, the level of sAXL was significantly increased in patients with plexiform tumors compared to patients with only dermal neurofibromas, further supporting the role of sAXL as a marker for NF1 related tumor burden.

  • 66.
    Jokipii-Lukkari, Soile
    et al.
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC). Umeå Plant Science Centre, Department of Forest Genetics and Plant Physiology, Sveriges Lantbruksuniversitet, SE-901 83 Umeå, Sweden.
    Delhomme, Nicolas
    Schiffthaler, Bastian
    Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC). Umeå University, Faculty of Science and Technology, Department of Plant Physiology.
    Mannapperuma, Chanaka
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    Prestele, Jakob
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    Nilsson, Ove
    Street, Nathaniel
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    Tuominen, Hannele
    Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC). Umeå University, Faculty of Science and Technology, Department of Plant Physiology.
    Transcriptional Roadmap to Seasonal Variation in Wood Formation of Norway Spruce2018In: Plant Physiology, ISSN 0032-0889, E-ISSN 1532-2548, Vol. 176, no 4, p. 2851-2870Article in journal (Refereed)
    Abstract [en]

    Seasonal cues influence several aspects of the secondary growth of tree stems, including cambial activity, wood chemistry, and transition to latewood formation. We investigated seasonal changes in cambial activity, secondary cell wall formation, and tracheid cell death in woody tissues of Norway spruce (Picea abies) throughout one seasonal cycle. RNA sequencing was performed simultaneously in both the xylem and cambium/phloem tissues of the stem. Principal component analysis revealed gradual shifts in the transcriptomes that followed a chronological order throughout the season. A notable remodeling of the transcriptome was observed in the winter, with many genes having maximal expression during the coldest months of the year. A highly coexpressed set of monolignol biosynthesis genes showed high expression during the period of secondary cell wall formation as well as a second peak in midwinter. This midwinter peak in expression did not trigger lignin deposition, as determined by pyrolysis-gas chromatography/mass spectrometry. Coexpression consensus network analyses suggested the involvement of transcription factors belonging to the ASYMMETRIC LEAVES2/LATERAL ORGAN BOUNDARIES and MYELOBLASTOSIS-HOMEOBOX families in the seasonal control of secondary cell wall formation of tracheids. Interestingly, the lifetime of the latewood tracheids stretched beyond the winter dormancy period, correlating with a lack of cell death-related gene expression. Our transcriptomic analyses combined with phylogenetic and microscopic analyses also identified the cellulose and lignin biosynthetic genes and putative regulators for latewood formation and tracheid cell death in Norway spruce, providing a toolbox for further physiological and functional assays of these important phase transitions.

  • 67.
    Kaarniranta, Kai
    et al.
    Department of Anatomy, University of Kuopio, Kuopio, Finland.
    Holmberg, Carina
    Turku Centre for Biotechnology, University of Turku, Åbo Akademi University, Turku, Finland; Department of Biochemistry and Pharmacy, Åbo Akademi University, Turku, Finland.
    Lammi, Mikko
    Department of Anatomy, University of Kuopio, Kuopio, Finland.
    Eriksson, John
    Turku Centre for Biotechnology, University of Turku, Åbo Akademi University, Turku, Finland.
    Sistonen, Lea
    Turku Centre for Biotechnology, University of Turku, Åbo Akademi University, Turku, Finland; Department of Biology, Åbo Akademi University, Turku, Finland.
    Helminen, Heikki
    Department of Anatomy, University of Kuopio, Kuopio, Finland.
    Primary chondrocytes resist hydrostatic pressure-induced stress while primary synovial cells and fibroblasts show modified Hsp70 response.2001In: Osteoarthritis and Cartilage, ISSN 1063-4584, E-ISSN 1522-9653, Vol. 9, no 1, p. 7-13, article id 11178942Article in journal (Refereed)
    Abstract [en]

    OBJECTIVE: During joint loading, chondrocytes in the articular cartilage are subjected to gradients of high compressive hydrostatic pressure (HP). In response to diverse chemical or physical stresses, heat shock genes are induced to express heat shock proteins (Hsps). This study sought to examine the role of Hsps in baroresistance in primary bovine chondrocytes and synovial cells, as well as in primary human fibroblasts.

    METHODS: Northern blotting was used to analyze the steady-state levels of hsp70 mRNA in the primary cells exposed to HP or heat stress. Hsp70 protein accumulation was analyzed by Western blotting, and the DNA-binding activity was examined by gel mobility shift assay.

    RESULTS: Primary bovine chondrocytes which have been adapted to live under pressurized conditions showed negligible Hsp70 response upon HP loading, whereas primary bovine synovial cells and human fibroblasts accumulated hsp70 mRNA and protein when subjected to HP. The response was initiated without activation of the heat shock transcription factor 1. Interestingly, pre-conditioning of the barosensitive fibroblasts with HP or heat shock reduced the Hsp70 response, indicating induction of baroresistance.

    CONCLUSION: This study suggests that Hsp70 can play an important role in the early stages of adaptation of cells to HP. Thus, the Hsp70 gene expression upon HP loading may serve as one indicator of the chondrocytic phenotype of the cells. This can be of use in the treatment of cartilage lesions.

  • 68.
    Kaarniranta, Kai
    et al.
    Department of Anatomy, University of Kuopio, Kuopio,Finland; Department of Neurosciences and Neurology, University of Kuopio, Kuopio, Finland.
    Oksala, Niku
    Department of Surgery, Kuopio University Hospital, Kuopio, Finland.
    Lammi, Mikko
    Department of Anatomy, University of Kuopio, Kuopio, Finland.
    Helminen, Heikki
    Department of Anatomy, University of Kuopio, Kuopio, Finland.
    Sistonen, Lea
    Department of Cell Biology, Åbo Academi, Turku, Finland; Center of Biotechnology, University of Turku, Turku, Finland.
    Solustressin tutkimuksesta kliinisiin läpimurtoihin? [From research of cellular stress to various clinical break through innovations?]2001In: Duodecim, ISSN 0012-7183, E-ISSN 2242-3281, Vol. 117, no 22, p. 2266-2272, article id 12183959Article, review/survey (Refereed)
    Abstract [fi]

    Fysikaalisen tai kemiallisen stressin seurauksena useiden geenien aktiivisuus vähenee,kun taas lämpösokki- eli stressigeenien induktio lisääntyy. Stressigeenit koodaavat lämpösokkiproteiineja(Hsp), jotka toimivat soluissa kaperoneina, »avustajina», auttaensolujen proteiineja laskostumaan oikein translaatiossa, kalvon läpi kuljetuksessa tai esimerkiksikorkean lämpötilan aiheuttaman vaurion jälkeen. Viime vuosina lämpösokkiproteiinienkliininen merkitys useiden sairauksien patogeneesissä, diagnostiikassa ja ennusteenmäärittämisessä on alkanut selvitä. Merkittävimmät kliiniset löydökset liittyvätiskeemisiin prosesseihin, kuten sydän- ja aivoinfarkteihin, useisiin neoplasioihin ja ikääntymiseen.Tässä katsauksessa käsittelemme stressigeenien säätelyä, Hsp70-stressiproteiinienkliinisiä yhteyksiä ja niiden mahdollisia hoitosovelluksia iskeemisissä, neoplastisissaja degeneratiivisissa prosesseissa.

  • 69. Kaneko, H
    et al.
    Mehrotra, M
    Alander, C
    Lerner, Ulf
    Umeå University, Faculty of Medicine, Department of Odontology, Oral Cell Biology.
    Pilbeam, C
    Raisz, L
    Effects of prostaglandin E-2 and lipopolysaccharide on osteoclastogenesis in RAW 264.7 cells2007In: Prostaglandins, Leukotrienes and Essential Fatty Acids, ISSN 0952-3278, E-ISSN 1532-2823, Vol. 77, no 3-4, p. 181-186Article in journal (Refereed)
    Abstract [en]

    Introduction: Prostaglandins (PGs) can act on both hematopoietic and osteoblastic lineages to enhance osteoclast formation.

    Methods: We examined PGE(2) stimulated osteoclastogenesis in RAW 264.7 cells and the role of endogenous PGE2 in lipopolysaccharide (LPS) stimulated osteoclastogenesis.

    Results: RANKL (1-100ng/ml) increased formation of osteoclasts, defined as tartrate resistant acid phosphatase multinucleated cells, with peak effects at 30 ng/ml. Addition of PGE2 (0-01-1.0 mu M) to RANKL (30 ng/ml) dose dependently increased osteoclast number 30-150%. Use of NS-398 (0.1 mu M) or indomethacin (Indo, 1.0 mu M) to block endogenous PG synthesis had little effect on the response to RANKL alone but significantly decreased the response to PGE2. Addition of LPS (100 ng/ml) to RANKL increased osteoclast number 50%, and this response was significantly decreased by NS-398 and Indo. RANKL and PGE2 produced small, additive increases in COX-2 mRNA levels, while LPS produced a larger increase. PG release into the medium was not increased by RANKL and PGE2 but markedly increased by LPS.

    Conclusion: We conclude that RANKL stimulated osteoclastogenesis can be enhanced by PGE2 and LPS though direct effects on the hematopoietic cell lineage and that these effects may be mediated in part by induction of COX-2 and enhanced intracellular PG production.

  • 70. Khmelinskii, Anton
    et al.
    Meurer, Matthias
    Duishoev, Nurlanbek
    Delhomme, Nicolas
    Knop, Michael
    Seamless gene tagging by endonuclease-driven homologous recombination.2011In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 6, no 8Article in journal (Refereed)
    Abstract [en]

    Gene tagging facilitates systematic genomic and proteomic analyses but chromosomal tagging typically disrupts gene regulatory sequences. Here we describe a seamless gene tagging approach that preserves endogenous gene regulation and is potentially applicable in any species with efficient DNA double-strand break repair by homologous recombination. We implement seamless tagging in Saccharomyces cerevisiae and demonstrate its application for protein tagging while preserving simultaneously upstream and downstream gene regulatory elements. Seamless tagging is compatible with high-throughput strain construction using synthetic genetic arrays (SGA), enables functional analysis of transcription antisense to open reading frames and should facilitate systematic and minimally-invasive analysis of gene functions.

  • 71.
    Kindstedt, Elin
    et al.
    Umeå University, Faculty of Medicine, Department of Odontology.
    Koskinen Holm, Cecilia
    Umeå University, Faculty of Medicine, Department of Odontology.
    Palmqvist, Py
    Umeå University, Faculty of Medicine, Department of Odontology.
    Sjöström, Mats
    Umeå University, Faculty of Medicine, Department of Odontology.
    Lejon, Kristina
    Umeå University, Faculty of Medicine, Department of Clinical Microbiology.
    Lundberg, Pernilla
    Umeå University, Faculty of Medicine, Department of Odontology.
    Discovery of Innate Lymphoid Cells in Gingivitis and PeriodontitisManuscript (preprint) (Other academic)
    Abstract [en]

    AIM: Innate lymphoid cells (ILCs) are the most recently identified leukocytes of the immune system and these cells are increasingly acknowledged to play important roles in host defence and tissue repair. ILCs can also contribute to inflammatory diseases such as asthma and colitis. We analysed the presence and proportions of the different ILC subsets (ILC1, ILC2 and ILC3) in gingivitis and periodontitis. Furthermore, we investigated if ILCs express nuclear factor kappa-B ligand (RANKL), a cytokine crucial for osteoclast differentiation and bone resorption.

    MATERIALS AND METHODS: We collected gingivitis and periodontitis soft tissue and characterised ILC subsets including RANKL expression in single cell suspensions using flow cytometry.

    RESULTS: Although not statistically significant, the total number of ILCs detected was twice as many in periodontitis compared to gingivitis. The majority of ILCs, in both conditions, were ILC1s with a 2.5-fold increase of ILC1s in periodontitis compared to gingivitis. Furthermore, we found RANKL expression exclusively expressed on ILC1s.

    CONCLUSIONS: Our discovery of the presence of ILCs in gingivitis and periodontitis and concomitant expression of RANKL in ILC1 suggest that these cells may be of importance in periodontal disease. In addition, our findings provide new insights into the field of oral immunology. 

  • 72. Klenell, Markus
    et al.
    Morita, Shigeto
    Tiemblo-Olmo, Mercedes
    Mühlenbock, Per
    Karpinski, Stanislaw
    Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC). Department of Botany, Stockholm University, SE-106 91 Stockholm, Sweden .
    Karpinska, Barbara
    Involvement of the chloroplast signal recognition particle cpSRP43 in acclimation to conditions promoting photooxidative stress in Arabidopsis2005In: Plant and Cell Physiology, ISSN 0032-0781, E-ISSN 1471-9053, Vol. 46, no 1, p. 118-129Article in journal (Refereed)
    Abstract [en]

    In this study, we have investigated the role of the CAO gene (coding for the chloroplast recognition particle cpSRP43) in the protection against and acclimation to environmental conditions that promote photooxidative stress. Deficiency of cpSRP43 in the Arabidopsis mutant chaos has been shown previously to lead to partial loss of a number of proteins of the photosystem II (PSII) antennae. In addition, as reported here, mutant plants have lower growth rates and reduced lignin contents under laboratory conditions. However, chaos seedlings showed significantly higher tolerance to photooxidative stress under both tightly controlled laboratory conditions and highly variable conditions in the field. This greater tolerance of chaos plants was manifested in less photooxidative damage together with faster growth recovery in young seedlings. It was also associated with a lower production of H2O2, lower ascorbate levels and less induction of ascorbate peroxidases. Under field conditions, chaos exhibited better overall photosynthetic performance and had higher survival rates. Expression of the CAO gene may be regulated by a light-dependent chloroplastic redox signalling pathway, and was inhibited during acclimation to high light and chilling temperatures, simultaneously with induction of ascorbate peroxidases. It is concluded that the presence/absence of the CAO gene has an impact on photo-produced H2O2, lignification in the hypocotyls and on the plant's susceptibility to photooxidative stress. Therefore, regulation of the CAO gene may be part of the plant's system for acclimation to high light and chilling temperatures.

  • 73. Klionsky, Daniel J.
    et al.
    Carlsson, Sven R.
    Umeå University, Faculty of Medicine, Department of Medical Biochemistry and Biophysics.
    Zughaier, Susu M.
    Guidelines for the use and interpretation of assays for monitoring autophagy (3rd edition)2016In: Autophagy, ISSN 1554-8627, E-ISSN 1554-8635, Vol. 12, no 1, p. 1-222Article in journal (Refereed)
  • 74.
    Kunz, Sabine
    Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC). Umeå University, Faculty of Science and Technology, Department of Plant Physiology.
    Sugar-modulated gene expression and cell division in cell culture and seedlings of A. thaliana2014Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Throughout their life cycle, plants adjust growth in response to their developmental and environmental situation within the limits of their energetic capacities. This capacity is defined by the local sugar availability, which is constantly modulated through synthesis, transport and consumption of sugar. The monitoring of sugar presence is carried out by a complex signalling network in which simple sugars (e.g. glucose, fructose and sucrose) act as metabolic signals for the modulation of physiological processes. However, often it remains unclear whether the regulation is induced by the simple sugars themselves or by their derivatives generated during sugar metabolism. This thesis focuses on the dissection of distinct sugar signals, their generation, perception and impact on the modulation of gene expression and cell division both in cell culture and young seedlings.

    Based on a stem-cell-like A. thaliana cell culture, which could be sustained in a hormone-free media, a new biological system, supplied with Xyl as the only carbon source was developed. The performance of a variety of sugar and sugar analogue treatments in this novel system allowed for the identification of sugar-responsive candidate genes, which were specifically regulated by glucose, fructose and sucrose. For several genes (e.g. bZIP63, AT5g22920, TPS9, MGD2 and BT2), this regulation required both sugar transport into the cytosol and metabolisation for the generation of the signal. Furthermore, gene expression analyses in young A. thaliana seedlings indicated the requirement for the catalytic activity of hexokinase 1 in the regulation of bZIP63, Atg22920 and BT2 under conditions of a perturbed carbohydrate balance. These findings have been combined in a proposed model for the transcriptional regulation of bZIP63, AT5g22920, TPS9, MGD2 and BT2, which further proposes a function of those genes in the regulation of cell division.

    The optimisation of a protocol for long-term real-time live-cell imaging provided a valuable tool to show that, similar to gene expression, the progression of cell division depended on a sugar-type-specific regulation at the single-cell level; this regulation was most likely caused by prolongation of the interphase. Together with the observation of cell death and growth arrest of the primary root in intact seedlings in response to the glucose analogue 2dog, this led to the conclusion that sugar signals themselves were sufficient to induce cell division. However, the continuation of cell cycle progression and consequently organ growth over long-time required the availability of the energy contained in the sugar.

  • 75.
    Kunz, Sabine
    et al.
    Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    Ménard, Delphine
    Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    Kleczkowski, Leszek
    Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    Pesquet, Edouard
    Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    Monitoring the role of distinct sugars on cell division in Arabidopsis plant cells and seedlingsManuscript (preprint) (Other academic)
    Abstract [en]

    Within the last decades, research on sugar-dependent plant growth provided evidence for a directregulation of cell division by sugars. Recently we showed, in A. thaliana cell suspension cultures, thatdistinct sugars differentially regulate a rapid transcriptional response of genes, some of which functionduring the cell cycle progression. In order to assess the relationship between sugar species and celldivision, we developed a new methodology for long-term real-time live-cell imaging on dividing A.thaliana cell suspension cultures. This technique, using cells grown in hormone-free media, allowed toestimate the cell cycle synchronicity and efficiency of an entire cell population and to monitor thedynamics and geometry of cell division in single cells in response to a given sugars. A marker cell lineconstitutively expressing TUA::GFP, a protein that labels microtubule-based structures hallmarkingprogression of the mitotic division, was used to measure the sugar-dependent efficiency andsynchronicity of the cell cycle progression. Altogether, we were able to confirm the distinct relationshipsof specific sugar molecules on the cell cycle progression at a single cell level. Cell division efficiencyand synchronicity were altered when grown on the different sugars sucrose, glucose and xylose.Interestingly, the progression of the mitotic division appeared unaffected by the sugar species supplied,indicating that length of the interphase is likely to control the cell division rate. In contrast, treatment ofA. thaliana cell cultures and seedlings with the Glc-analogue 2-deoxy-glucose (2dog) led to growtharrest and to cell death during long exposure. The growth resulting from 2dog removal in cell culturesand seedlings showed the unique feature of plants to induce new active zones of cell division.

  • 76.
    Kuzhandaivel, Anujaianthi
    et al.
    Linköpings universitet, Avdelningen för cellbiologi.
    Schultz, Sebastian W.
    Linköpings universitet, Avdelningen för cellbiologi.
    Alkhori, Liza
    Linköpings universitet, Avdelningen för cellbiologi.
    Alenius, Mattias
    Linköpings universitet, Avdelningen för cellbiologi.
    Cilia-Mediated Hedgehog Signaling in Drosophila2014In: Cell reports, ISSN 2211-1247, E-ISSN 2211-1247, Vol. 7, no 3, p. 672-680Article in journal (Refereed)
    Abstract [en]

    Cilia mediate Hedgehog (Hh) signaling in vertebrates and Hh deregulation results in several clinical manifestations, such as obesity, cognitive disabilities, developmental malformations, and various cancers. Drosophila cells are nonciliated during development, which has led to the assumption that cilia-mediated Hh signaling is restricted to vertebrates. Here, we identify and characterize a cilia-mediated Hh pathway in Drosophila olfactory sensory neurons. We demonstrate that several fundamental key aspects of the vertebrate cilia pathway, such as ciliary localization of Smoothened and the requirement of the intraflagellar transport system, are present in Drosophila. We show that Cos2 and Fused are required for the ciliary transport of Smoothened and that cilia mediate the expression of the Hh pathway target genes. Taken together, our data demonstrate that Hh signaling in Drosophila can be mediated by two pathways and that the ciliary Hh pathway is conserved from Drosophila to vertebrates.

  • 77. Kuznetsov, Nikolai V
    et al.
    Sandblad, Linda
    Department of Cell and Molecular Biology, Karolinska Institutet, Stockholm, Sweden.
    Hase, Manuela E
    Hunziker, Andreas
    Hergt, Michaela
    Cordes, Volker C
    The evolutionarily conserved single-copy gene for murine Tpr encodes one prevalent isoform in somatic cells and lacks paralogs in higher eukaryotes.2002In: Chromosoma, ISSN 0009-5915, E-ISSN 1432-0886, Vol. 111, no 4, p. 236-255Article in journal (Refereed)
    Abstract [en]

    Vertebrate Tpr and its probable homologs in insects and yeast are heptad repeat-dominated nuclear proteins of M(r) 195,000 to M(r) 267,000 the functions of which are still largely unknown. Whereas two homologs exist in Saccharomyces cerevisiae, it has remained uncertain whether metazoans possess different paralogs or isoforms of Tpr that might explain controversial reports on the subcellular localization of this protein. To address these possibilities, we first determined the sequence and structure of the murine tpr gene, revealing a TATA box-less gene of approximately 57 kb and 52 exons. Southern hybridization of genomic DNA and radiation hybrid mapping showed that murine tpr exists as a single-copy gene on chromosome 1; RNA blotting analyses and EST (expressed sequence tag) database mining revealed that its expression results in only one major mRNA in embryonic and most adult tissues. Accordingly, novel antibodies against the N- and C-terminus of Tpr identified the full-length protein as the major translation product in different somatic cell types; reinvestigation of Tpr localization by confocal microscopy corroborated a predominant localization at the nuclear pore complexes in these cells. Antibody specificity and reliability of Tpr localization was demonstrated by post-transcriptional tpr gene silencing using siRNAs that eliminated the Tpr signal at the nuclear periphery but did not affect intranuclear staining of Tpr-unrelated proteins. Finally, we defined several sequence and structural features that characterize Tpr polypeptides in different species and used these as a guideline to search whole-genome sequence databases for putative paralogs of Tpr in higher eukaryotes. This approach resulted in identification of the Tpr orthologs in Arabidopsis thaliana and Caenorhabditis elegans, but also in the realization that no further paralogs of Tpr exist in several metazoan model organisms or in humans. In summary, these results reveal Tpr to be a unique protein localized at the nuclear periphery of the somatic cell in mammals.

  • 78. Ladurner, Rene
    et al.
    Kreidl, Emanuel
    Ivanov, Miroslav P
    Ekker, Heinz
    Idarraga-Amado, Maria Helena
    Busslinger, Georg A
    Wutz, Gordana
    Cisneros, David A.
    Research Institute of Molecular Pathology (IMP), Vienna Biocenter (VBC), Vienna, Austria.
    Peters, Jan-Michael
    Sororin actively maintains sister chromatid cohesion2016In: EMBO Journal, ISSN 0261-4189, E-ISSN 1460-2075, Vol. 35, no 6, p. 635-653Article in journal (Refereed)
    Abstract [en]

    Cohesion between sister chromatids is established during DNA replication but needs to be maintained to enable proper chromosome-spindle attachments in mitosis or meiosis. Cohesion is mediated by cohesin, but also depends on cohesin acetylation and sororin. Sororin contributes to cohesion by stabilizing cohesin on DNA. Sororin achieves this by inhibiting WAPL, which otherwise releases cohesin from DNA and destroys cohesion. Here we describe mouse models which enable the controlled depletion of sororin by gene deletion or auxin-induced degradation. We show that sororin is essential for embryonic development, cohesion maintenance, and proper chromosome segregation. We further show that the acetyltransferases ESCO1 and ESCO2 are essential for stabilizing cohesin on chromatin, that their only function in this process is to acetylate cohesin's SMC3 subunit, and that DNA replication is also required for stable cohesin-chromatin interactions. Unexpectedly, we find that sororin interacts dynamically with the cohesin complexes it stabilizes. This implies that sororin recruitment to cohesin does not depend on the DNA replication machinery or process itself, but on a property that cohesin acquires during cohesion establishment.

  • 79. Laitinen, Teresa
    et al.
    Morreel, Kris
    Delhomme, Nicolas
    Gauthier, Adrien
    Schiffthaler, Bastian
    Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC). Umeå University, Faculty of Science and Technology, Department of Plant Physiology.
    Nickolov, Kaloian
    Brader, Günter
    Lim, Kean-Jin
    Teeri, Teemu H.
    Street, Nathaniel R.
    Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC). Umeå University, Faculty of Science and Technology, Department of Plant Physiology.
    Boerjan, Wout
    Kärkönen, Anna
    A Key Role for Apoplastic H2O2 in Norway Spruce Phenolic Metabolism2017In: Plant Physiology, ISSN 0032-0889, E-ISSN 1532-2548, Vol. 174, no 3, p. 1449-1475Article in journal (Refereed)
    Abstract [en]

    Apoplastic events such as monolignol oxidation and lignin polymerization are difficult to study in intact trees. To investigate the role of apoplastic hydrogen peroxide (H2O2) in gymnosperm phenolic metabolism, an extracellular lignin-forming cell culture of Norway spruce (Picea abies) was used as a research model. Scavenging of apoplastic H2O2 by potassium iodide repressed lignin formation, in line with peroxidases activating monolignols for lignin polymerization. Time-course analyses coupled to candidate substrate-product pair network propagation revealed differential accumulation of low-molecular-weight phenolics, including (glycosylated) oligolignols, (glycosylated) flavonoids, and proanthocyanidins, in lignin-forming and H2O2-scavenging cultures and supported that monolignols are oxidatively coupled not only in the cell wall but also in the cytoplasm, where they are coupled to other monolignols and proanthocyanidins. Dilignol glycoconjugates with reduced structures were found in the culture medium, suggesting that cells are able to transport glycosylated dilignols to the apoplast. Transcriptomic analyses revealed that scavenging of apoplastic H2O2 resulted in remodulation of the transcriptome, with reduced carbon flux into the shikimate pathway propagating down to monolignol biosynthesis. Aggregated coexpression network analysis identified candidate enzymes and transcription factors for monolignol oxidation and apoplastic H2O2 production in addition to potential H2O2 receptors. The results presented indicate that the redox state of the apoplast has a profound influence on cellular metabolism.

  • 80.
    Lammi, Mikko
    et al.
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB). Key Laboratory of Trace Elements and Endemic Diseases, National Health and Family Planning, Institute of Endemic Diseases, School of Public Health of Health Science Center, Xi'an Jiaotong University, Xi'an, China.
    Piltti, Juha
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB). Nordlab Kokkola, Keski-Pohjanmaa Central Hospital Soite, Kokkola, Finland.
    Prittinen, Juha
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB).
    Qu, Chengjuan
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB).
    Challenges in fabrication of tissue-engineered cartilage with correct cellular colonization and extracellular matrix assembly2018In: International Journal of Molecular Sciences, ISSN 1422-0067, E-ISSN 1422-0067, Vol. 19, no 9, article id 2700Article, review/survey (Refereed)
    Abstract [en]

    A correct articular cartilage ultrastructure regarding its structural components and cellularity is important for appropriate performance of tissue-engineered articular cartilage. Various scaffold-based, as well as scaffold-free, culture models have been under development to manufacture functional cartilage tissue. Even decellularized tissues have been considered as a potential choice for cellular seeding and tissue fabrication. Pore size, interconnectivity, and functionalization of the scaffold architecture can be varied. Increased mechanical function requires a dense scaffold, which also easily restricts cellular access within the scaffold at seeding. High pore size enhances nutrient transport, while small pore size improves cellular interactions and scaffold resorption. In scaffold-free cultures, the cells assemble the tissue completely by themselves; in optimized cultures, they should be able to fabricate native-like tissue. Decellularized cartilage has a native ultrastructure, although it is a challenge to obtain proper cellular colonization during cell seeding. Bioprinting can, in principle, provide the tissue with correct cellularity and extracellular matrix content, although it is still an open question as to how the correct molecular interaction and structure of extracellular matrix could be achieved. These are challenges facing the ongoing efforts to manufacture optimal articular cartilage.

  • 81.
    Lammi, Pirkko
    et al.
    Department of Clinical Chemistry, Kuopio University Hospital, Kuopio, Finland.
    Inkinen, Ritva
    Department of Anatomy, University of Kuopio, Kuopio, Finland.
    von der Mark, Klaus
    Institute for Experimental Medicine, University of Erlangen-Nurenberg, Erlangen, Germany.
    Puustjärvi, K
    Department of Physical Medicine and Rehabilitation, Kuopio University Hospital, Kuopio, Finland.
    Arokoski, Jari
    Department of Physical Medicine and Rehabilitation, Kuopio University Hospital, Kuopio, Finland.
    Hyttinen, Mika
    Department of Anatomy, University of Kuopio, Kuopio, Finland.
    Lammi, Mikko
    Department of Anatomy, University of Kuopio, Kuopio, Finland.
    Localization of type X collagen in the intervertebral disc of mature beagle dogs.1998In: Matrix Biology, ISSN 0945-053X, E-ISSN 1569-1802, Vol. 17, no 6, p. 449-453, article id 9840446Article in journal (Refereed)
    Abstract [en]

    Type X collagen expression in intervertebral disc of young adult beagle dogs (n = 10) was studied. Type X collagen was immunostained mainly pericellularly in the central area of the vertebral endplate, but interterritorial staining there was also present. Annulus fibrosus and nucleus pulposus did not usually stain for type X collagen. However, immunostaining of nucleus pulposus for type X collagen with a simultaneous expression of collagen alpha1(X) mRNA was observed in one dog. A weak staining was observed in two other animals with a weak collagen alpha1(X) mRNA signal. In annulus fibrosus, lamellar staining was observed in two dogs. In three animals, type X collagen mRNAs were observed in the outer edge of the annulus fibrosus, but immunohistochemical staining did not always correlate with in situ hybridization signals. In conclusion, intervertebral disc type X collagen was mainly expressed in the cartilaginous endplate. In some apparently healthy animals there was type X collagen expression in the nucleus pulposus and also in the annulus fibrosus.

  • 82.
    Laptenko, Oleg
    et al.
    Department of Cell Biology, School of Osteopathic Medicine at Stratford, University of Medicine and Dentistry of New Jersey, Stratford, NJ, USA.
    Kim, Seung-Sup
    Department of Biochemistry, New York University School of Medicine, New York, NY, USA.
    Lee, Jookyung
    Department of Cell Biology, School of Osteopathic Medicine at Stratford, University of Medicine and Dentistry of New Jersey, Stratford, NJ, USA.
    Starodubtseva, Marina
    Department of Cell Biology, School of Osteopathic Medicine at Stratford, University of Medicine and Dentistry of New Jersey, Stratford, NJ, USA.
    Cava, Felipe
    Centro de Biología Molecular 'Severo Ochoa' CSIC-UAM, Campus de Cantoblanco, Madrid, Spain.
    Berenguer, Jose
    Centro de Biología Molecular 'Severo Ochoa' CSIC-UAM, Campus de Cantoblanco, Madrid, Spain.
    Kong, Xiang-Peng
    Department of Biochemistry, New York University School of Medicine, New York, NY, USA.
    Borukhov, Sergei
    Department of Cell Biology, School of Osteopathic Medicine at Stratford, University of Medicine and Dentistry of New Jersey, Stratford, NJ, USA.
    pH-dependent conformational switch activates the inhibitor of transcription elongation2006In: EMBO Journal, ISSN 0261-4189, E-ISSN 1460-2075, Vol. 25, no 10, p. 2131-2141Article in journal (Refereed)
    Abstract [en]

    Gfh1, a transcription factor from Thermus thermophilus, inhibits all catalytic activities of RNA polymerase (RNAP). We characterized the Gfh1 structure, function and possible mechanism of action and regulation. Gfh1 inhibits RNAP by competing with NTPs for coordinating the active site Mg2+ ion. This coordination requires at least two aspartates at the tip of the Gfh1 N-terminal coiled-coil domain (NTD). The overall structure of Gfh1 is similar to that of the Escherichia coli transcript cleavage factor GreA, except for the flipped orientation of the C-terminal domain (CTD). We show that depending on pH, Gfh1-CTD exists in two alternative orientations. At pH above 7, it assumes an inactive 'flipped' orientation seen in the structure, which prevents Gfh1 from binding to RNAP. At lower pH, Gfh1-CTD switches to an active 'Gre-like' orientation, which enables Gfh1 to bind to and inhibit RNAP.

  • 83.
    Leary, Sophie E. C.
    et al.
    Biomedical Sciences Department, Defence Evaluation and Research Agency, Porton Down, Salisbury, Wiltshire, SP4 0JQ, U.K..
    Griffin, Kate F.
    Biomedical Sciences Department, Defence Evaluation and Research Agency, Porton Down, Salisbury, Wiltshire, SP4 0JQ, U.K..
    Galyov, Edouard E.
    Institute for Animal Health, Compton, Nr Newbury, Berkshire RG20 7NN, U.K..
    Hewer, Jason
    Biomedical Sciences Department, Defence Evaluation and Research Agency, Porton Down, Salisbury, Wiltshire, SP4 0JQ, U.K..
    Williamson, E. Diane
    Biomedical Sciences Department, Defence Evaluation and Research Agency, Porton Down, Salisbury, Wiltshire, SP4 0JQ, U.K..
    Holmström, Anna
    Department of Microbiology, Defence Research Establishment, S-901 87 Umeå, Sweden.
    Forsberg, Åke Forsberg
    Department of Microbiology, Defence Research Establishment, S-901 87 Umeå, Sweden.
    Titball, Richard W.
    Biomedical Sciences Department, Defence Evaluation and Research Agency, Porton Down, Salisbury, Wiltshire, SP4 0JQ, U.K..
    Yersinia outer proteins (YOPS) E, K and N are antigenic but non-protective compared to V antigen, in a murine model of bubonic plague1999In: Microbial Pathogenesis, ISSN 0882-4010, E-ISSN 1096-1208, Vol. 26, no 3, p. 159-169Article in journal (Refereed)
    Abstract [en]

    The pathogenic Yersiniae produce a range of virulence proteins, encoded by a 70 kb plasmid, which are essential for infection, and also form part of a contact-dependent virulence mechanism. One of these proteins, V antigen, has been shown to confer a high level of protection against parenteral infection with Y. pestis in murine models, and is considered to be a protective antigen. In this study, the protective efficacy of V antigen has been compared in the same model with that of other proteins (YopE, YopK and YopN), which are part of the contact-dependent virulence mechanism. Mice immunised with two intraperitoneal doses of V antigen or each of the Yops, administered with either Alhydrogel or interleukin-12, produced high antigen-specific serum IgG titres. As shown in previous studies, V+Alhydrogel was fully protective, and 5/5 mice survived a subcutaneous challenge with 90 or 9x10(3) LD50's of Y. pestis GB. In addition, these preliminary studies also showed that V+IL-12 was partially protective: 4/5 or 3/5 mice survived a challenge with 90 or 9x10(3) LD50's, respectively. In contrast, none of the mice immunised with the Yops survived the challenges, and there was no significant delay in the mean time to death compared to mice receiving a control protein. These results show that using two different vaccine regimens, Yops E, K and N, failed to elicit protective immune responses in a murine model of plague, whereas under the same conditions, V antigen was fully or partially protective.

  • 84. Leitner, Johannes
    et al.
    Retzer, Katarzyna
    Malenica, Nenad
    Bartkeviciute, Rasa
    Lucyshyn, Doris
    Jäger, Gunilla
    Umeå University, Faculty of Science and Technology, Department of Molecular Biology (Faculty of Science and Technology).
    Korbei, Barbara
    Byström, Anders
    Umeå University, Faculty of Science and Technology, Department of Molecular Biology (Faculty of Science and Technology).
    Luschnig, Christian
    Meta-regulation of Arabidopsis Auxin Responses Depends on tRNA Maturation2015In: Cell reports, ISSN 2211-1247, E-ISSN 2211-1247, Vol. 11, no 4, p. 516-526Article in journal (Refereed)
    Abstract [en]

    Polar transport of the phytohormone auxin throughout plants shapes morphogenesis and is subject to stringent and specific control. Here, we identify basic cellular activities connected to translational control of gene expression as sufficient to specify auxin-mediated development. Mutants in subunits of Arabidopsis Elongator, a protein complex modulating translational efficiency via maturation of tRNAs, exhibit defects in auxin-controlled developmental processes, associated with reduced abundance of PIN-formed (PIN) auxin transport proteins. Similar anomalies are observed upon interference with tRNA splicing by downregulation of RNA ligase (AtRNL), pointing to a general role of tRNA maturation in auxin signaling. Elongator Protein 6 (ELP6) and AtRNL expression patterns underline an involvement in adjusting PIN protein levels, whereas rescue of mutant defects by auxin indicates rate-limiting activities in auxin-controlled organogenesis. This emphasizes mechanisms in which auxin serves as a bottleneck for plant morphogenesis, translating common cellular activities into defined developmental readouts.

  • 85. Lesniewska, Joanna
    et al.
    Ohman, David
    Krzeslowska, Magdalena
    Kushwah, Sunita
    Barciszewska-Pacak, Maria
    Kleczkowski, Leszek A.
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    Sundberg, Bjorn
    Moritz, Thomas
    Mellerowicz, Ewa J.
    Defense Responses in Aspen with Altered Pectin Methylesterase Activity Reveal the Hormonal Inducers of Tyloses2017In: Plant Physiology, ISSN 0032-0889, E-ISSN 1532-2548, Vol. 173, no 2, p. 1409-1419Article in journal (Refereed)
    Abstract [en]

    Tyloses are ingrowths of parenchyma cells into the lumen of embolized xylem vessels, thereby protecting the remaining xylem from pathogens. They are found in heartwood, sapwood, and in abscission zones and can be induced by various stresses, but their molecular triggers are unknown. Here, we report that down-regulation of PECTIN METHYLESTERASE1 (PtxtPME1) in aspen (Populus tremula 3 tremuloides) triggers the formation of tyloses and activation of oxidative stress. We tested whether any of the oxidative stress-related hormones could induce tyloses in intact plantlets grown in sterile culture. Jasmonates, including jasmonic acid (JA) and methyl jasmonate, induced the formation of tyloses, whereas treatments with salicylic acid (SA) and 1-aminocyclopropane-1carboxylic acid (ACC) were ineffective. SA abolished the induction of tyloses by JA, whereas ACC was synergistic with JA. The ability of ACC to stimulate tyloses formation when combined with JA depended on ethylene (ET) signaling, as shown by a decrease in the response in ET-insensitive plants. Measurements of internal ACC and JA concentrations in wild-type and ET-insensitive plants treated simultaneously with these two compounds indicated that ACC and JA regulate each other's concentration in an ET-dependent manner. The findings indicate that jasmonates acting synergistically with ethylene are the key molecular triggers of tyloses.

  • 86.
    Lin, Xialu
    et al.
    Key Laboratory of Trace Elements and Endemic Diseases of National Health and Family Planning Commission, Key Laboratory of Environment and Genes Related to Diseases of Ministry of Education, Collaborative Innovation Center of Endemic Diseases and Health Promotion in Silk Road Region, School of Public Health, Health Science Center, Xi'an Jiaotong University, Xi'an, China.
    Shao, Wanzhen
    Key Laboratory of Trace Elements and Endemic Diseases of National Health and Family Planning Commission, Key Laboratory of Environment and Genes Related to Diseases of Ministry of Education, Collaborative Innovation Center of Endemic Diseases and Health Promotion in Silk Road Region, School of Public Health, Health Science Center, Xi'an Jiaotong University, Xi'an, China.
    Yu, Fangfang
    Key Laboratory of Trace Elements and Endemic Diseases of National Health and Family Planning Commission, Key Laboratory of Environment and Genes Related to Diseases of Ministry of Education, Collaborative Innovation Center of Endemic Diseases and Health Promotion in Silk Road Region, School of Public Health, Health Science Center, Xi'an Jiaotong University, Xi'an, China.
    Xing, Ke
    Xi'an Hong Hui Hospital, Health Science Center, Xi'an Jiaotong University, Xi'an, China.
    Liu, Huan
    Key Laboratory of Trace Elements and Endemic Diseases of National Health and Family Planning Commission, Key Laboratory of Environment and Genes Related to Diseases of Ministry of Education, Collaborative Innovation Center of Endemic Diseases and Health Promotion in Silk Road Region, School of Public Health, Health Science Center, Xi'an Jiaotong University, Xi'an, China.
    Zhang, Feng'e
    Key Laboratory of Trace Elements and Endemic Diseases of National Health and Family Planning Commission, Key Laboratory of Environment and Genes Related to Diseases of Ministry of Education, Collaborative Innovation Center of Endemic Diseases and Health Promotion in Silk Road Region, School of Public Health, Health Science Center, Xi'an Jiaotong University, Xi'an, China.
    Goldring, Mary B.
    Hospital for Special Surgery, Weill Cornell Medical College, New York, NY, USA.
    Lammi, Mikko J.
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB). Key Laboratory of Trace Elements and Endemic Diseases of National Health and Family Planning Commission, Key Laboratory of Environment and Genes Related to Diseases of Ministry of Education, Collaborative Innovation Center of Endemic Diseases and Health Promotion in Silk Road Region, School of Public Health, Health Science Center, Xi'an Jiaotong University, Xi'an, China.
    Guo, Xiong
    Key Laboratory of Trace Elements and Endemic Diseases of National Health and Family Planning Commission, Key Laboratory of Environment and Genes Related to Diseases of Ministry of Education, Collaborative Innovation Center of Endemic Diseases and Health Promotion in Silk Road Region, School of Public Health, Health Science Center, Xi'an Jiaotong University, Xi'an, China.
    Individual and combined toxicity of T-2 toxin and deoxynivalenol on human C-28/I2 and rat primary chondrocytes2019In: Journal of Applied Toxicology, ISSN 0260-437X, E-ISSN 1099-1263, Vol. 39, no 2, p. 343-353, article id 30251759Article in journal (Refereed)
    Abstract [en]

    Deoxynivalenol (DON) and T-2 toxin are prevalent mycotoxin contaminants in the food and feed stuffs worldwide, with non-negligible co-contamination and co-exposure conditions. Meanwhile, they are considerable risk factors for Kashin-Beck disease, a chronic endemic osteochondropathy. The aim of this study was to investigate the individual and combined cytotoxicity of DON and T-2 toxin on proliferating human C-28/I2 and newborn rat primary costal chondrocytes by MTT assay. Four molar concentration combination ratios of DON and T-2 toxin were used, 1:1 for R1 mixture, 10:1 for R10, 100:1 for R100 and 1000:1 for R1000. The toxicological interactions were quantified by the MixLow method. DON, T-2 toxin, and their mixtures all showed a clear dose-dependent toxicity for chondrocytes. The cytotoxicity of T-2 toxin was 285-fold higher than DON was in human chondrocytes, and 22-fold higher in the rat chondrocytes. The combination of DON and T-2 toxin was significantly synergistic at middle and high level concentrations of R10 mixtures in rat chondrocytes, but significantly antagonistic at the low concentrations of R100 mixtures in both cells and at the middle concentrations of R1000 mixtures in rat chondrocytes. These results indicated that the combined toxicity was influenced by the cell sensitivity for toxins, the difference between the combination ratio and equitoxic ratio, the concentrations and other factors.

  • 87. Liu, Qinsong
    et al.
    Vain, Thomas
    Viotti, Corrado
    Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC). Institute of Biochemistry and Biology, Plant Physiology, University of Potsdam, 14476 Potsdam, Germany.
    Doyle, Siamsa M.
    Tarkowska, Danuse
    Novak, Ondrej
    Zipfel, Cyril
    Sitbon, Folke
    Robert, Stephanie
    Hofius, Daniel
    Vacuole Integrity Maintained by DUF300 Proteins Is Required for Brassinosteroid Signaling Regulation2018In: Molecular Plant, ISSN 1674-2052, E-ISSN 1752-9867, Vol. 11, no 4, p. 553-567Article in journal (Refereed)
    Abstract [en]

    Brassinosteroid (BR) hormone signaling controls multiple processes during plant growth and development and is initiated at the plasma membrane through the receptor kinase BRASSINOSTEROID INSENSITIVE1 (BRI1) together with co-receptors such as BRI1-ASSOCIATED RECEPTOR KINASE1 (BAK1). BRI1 abundance is regulated by endosomal recycling and vacuolar targeting, but the role of vacuole-related proteins in BR receptor dynamics and BR responses remains elusive. Here, we show that the absence of two DUF300 domain-containing tonoplast proteins, LAZARUS1 (LAZ1) and LAZ1 HOMOLOG1 (LAZ1H1), causes vacuole morphology defects, growth inhibition, and constitutive activation of BR signaling. Intriguingly, tonoplast accumulation of BAK1 was substantially increased and appeared causally linked to enhanced BRI1 trafficking and degradation in laz1 laz1h1 plants. Since unrelated vacuole mutants exhibited normal BR responses, our findings indicate that DUF300 proteins play distinct roles in the regulation of BR signaling by maintaining vacuole integrity required to balance subcellular BAK1 pools and BR receptor distribution.

  • 88. Lopez, Ignacio
    et al.
    Tournillon, Anne-Sophie
    Martins, Rodrigo Prado
    Karakostis, Konstantinos
    Malbert-Colas, Laurence
    Nylander, Karin
    Umeå University, Faculty of Medicine, Department of Medical Biosciences.
    Fåhraeus, Robin
    Umeå University, Faculty of Medicine, Department of Medical Biosciences. Équipe Labellisée Ligue Contre le Cancer, Université Paris 7, INSERM UMR 1162 ‘Génomique Fonctionnelle des Tumeurs Solides’, Paris, France ; RECAMO, Masaryk Memorial Cancer Institute, Brno, Czech Republic.
    p53-mediated suppression of BiP triggers BIK-induced apoptosis during prolonged endoplasmic reticulum stress2017In: Cell Death and Differentiation, ISSN 1350-9047, E-ISSN 1476-5403, Vol. 24, no 10, p. 1717-1729Article in journal (Refereed)
    Abstract [en]

    Physiological and pathological conditions that affect the folding capacity of the endoplasmic reticulum (ER) provoke ER stress and trigger the unfolded protein response (UPR). The UPR aims to either restore the balance between newly synthesized and misfolded proteins or if the damage is severe, to trigger cell death. However, the molecular events underlying the switch between repair and cell death are not well understood. The ER-resident chaperone BiP governs the UPR by sensing misfolded proteins and thereby releasing and activating the three mediators of the UPR: PERK, IRE1 and ATF6. PERK promotes G2 cell cycle arrest and cellular repair by inducing the alternative translated p53 isoform p53.N40 (p53/47), which activates 14-3-3 sigma via suppression of p21(CDKN1A). Here we show that prolonged ER stress promotes apoptosis via a p53-dependent inhibition of BiP expression. This leads to the release of the pro-apoptotic BH3-only BIK from BiP and activation of apoptosis. Suppression of bip mRNA translation is mediated via the specific binding of p53 to the first 346-nt of the bip mRNA and via a p53 trans-suppression domain located within the first seven N-terminal amino acids of p53 Delta N40. This work shows how p53 targets BiP to promote apoptosis during severe ER stress and further illustrates how regulation of mRNA translation has a key role in p53-mediated regulation of gene expression during the UPR.

  • 89. Lopez, Ignacio
    et al.
    Tournillon, Anne-Sophie
    Nylander, Karin
    Umeå University, Faculty of Medicine, Department of Medical Biosciences.
    Fåhraeus, Robin
    Umeå University, Faculty of Medicine, Department of Medical Biosciences. Univ Paris 07, Equipe Labellisee Ligue Canc, Paris, France; INSERM, UMR Genom Fonct Tumeurs Solides 1162, Paris, France; Masaryk Mem Canc Inst, RECAMO, Brno, Czech Republic.
    p53-mediated control of gene expression via mRNA translation during Endoplasmic Reticulum stress2015In: Cell Cycle, ISSN 1538-4101, E-ISSN 1551-4005, Vol. 14, no 21, p. 3373-3378Article in journal (Refereed)
    Abstract [en]

    p53 is activated by different stress and damage pathways and regulates cell biological responses including cell cycle arrest, repair pathways, apoptosis and senescence. Following DNA damage, the levels of p53 increase and via binding to target gene promoters, p53 induces expression of multiple genes including p21(CDKN1A) and mdm2. The effects of p53 on gene expression during the DNA damage response are well mimicked by overexpressing p53 under normal conditions. However, stress to the Endoplasmic Reticulum (ER) and the consequent Unfolded Protein Response (UPR) leads to the induction of the p53/47 isoform that lacks the first 40 aa of p53 and to an active suppression of p21(CDKN1A) transcription and mRNA translation. We now show that during ER stress p53 also suppresses MDM2 protein levels via a similar mechanism. These observations not only raise questions about the physiological role of MDM2 during ER stress but it also reveals a new facet of p53 as a repressor toward 2 of its major target genes during the UPR. As suppression of p21(CDKN1A) and MDM2 protein synthesis is mediated via their coding sequences, it raises the possibility that p53 controls mRNA translation via a common mechanism that might play an important role in how p53 regulates gene expression during the UPR, as compared to the transcription-dependent gene regulation taking place during the DNA damage response.

  • 90. Magyar, Zoltan
    et al.
    Horvath, Beatrix
    Khan, Safina
    Mohammed, Binish
    Henriques, Rossana
    De Veylder, Lieven
    Bako, Laszlo
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    Scheres, Ben
    Boegre, Laszlo
    Arabidopsis E2FA stimulates proliferation and endocycle separately through RBR-bound and RBR-free complexes2012In: EMBO Journal, ISSN 0261-4189, E-ISSN 1460-2075, Vol. 31, no 6, p. 1480-1493Article in journal (Refereed)
    Abstract [en]

    Post-embryonic growth in plants depends on the continuous supply of undifferentiated cells within meristems. Proliferating cells maintain their competence for division by active repression of differentiation and the associated endocycle entry. We show by upregulation and downregulation of E2FA that it is required for maintaining proliferation, as well as for endocycle entry. While E2FB-RBR1 (retinoblastoma-related protein 1) complexes are reduced after sucrose addition or at elevated CYCD3;1 levels, E2FA maintains a stable complex with RBR1 in proliferating cells. Chromatin immunoprecipitation shows that RBR1 binds in the proximity of E2F promoter elements in CCS52A1 and CSS52A2 genes, central regulators for the switch from proliferation to endocycles. Overexpression of a truncated E2FA mutant (E2FA(Delta RB)) lacking the RBR1-binding domain interferes with RBR1 recruitment to promoters through E2FA, leading to decreased meristem size in roots, premature cell expansion and hyperactivated endocycle in leaves. E2F target genes, including CCS52A1 and CCS52A2, are upregulated in E2FADRB and e2fa knockout lines. These data suggest that E2FA in complex with RBR1 forms a repressor complex in proliferating cells to inhibit premature differentiation and endocycle entry. Thus, E2FA regulates organ growth via two distinct, sequentially operating pathways. The EMBO Journal (2012) 31, 1480-1493. doi:10.1038/emboj.2012.13; Published online 3 February 2012

  • 91. Majda, Mateusz
    et al.
    Grones, Peter
    Sintorn, Ida-Maria
    Vain, Thomas
    Milani, Pascale
    Krupinski, Pawel
    Zagorska-Marek, Beata
    Viotti, Corrado
    Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC). Institute of Biochemistry and Biology, Plant Physiology, University of Potsdam, 14476 Potsdam, Germany.
    Jonsson, Henrik
    Mellerowicz, Ewa J.
    Hamant, Olivier
    Robert, Stephanie
    Mechanochemical Polarization of Contiguous Cell Walls Shapes Plant Pavement Cells2017In: Developmental Cell, ISSN 1534-5807, E-ISSN 1878-1551, Vol. 43, no 3, p. 290-304Article in journal (Refereed)
    Abstract [en]

    The epidermis of aerial plant organs is thought to be limiting for growth, because it acts as a continuous load-bearing layer, resisting tension. Leaf epidermis contains jigsaw puzzle piece-shaped pavement cells whose shape has been proposed to be a result of subcellular variations in expansion rate that induce local buckling events. Paradoxically, such local compressive buckling should not occur given the tensile stresses across the epidermis. Using computational modeling, we show that the simplest scenario to explain pavement cell shapes within an epidermis under tension must involve mechanical wall heterogeneities across and along the anticlinal pavement cell walls between adjacent cells. Combining genetics, atomic force microscopy, and immunolabeling, we demonstrate that contiguous cell walls indeed exhibit hybrid mechanochemical properties. Such biochemical wall heterogeneities precede wall bending. Altogether, this provides a possible mechanism for the generation of complex plant cell shapes.

  • 92.
    Makoveichuk, Elena
    et al.
    Umeå University, Faculty of Medicine, Department of Medical Biosciences, Physiological chemistry.
    Vorrsjö, Evelina
    Umeå University, Faculty of Medicine, Department of Medical Biosciences, Physiological chemistry.
    Olivecrona, Thomas
    Umeå University, Faculty of Medicine, Department of Medical Biosciences, Physiological chemistry.
    Olivecrona, Gunilla
    Umeå University, Faculty of Medicine, Department of Medical Biosciences, Physiological chemistry.
    TNF-alpha decreases lipoprotein lipase activity in 3T3-L1 adipocytes by up-regulation of angiopoietin-like protein 42017In: Biochimica et Biophysica Acta - Molecular and Cell Biology of Lipids, ISSN 1388-1981, E-ISSN 1879-2618, Vol. 1862, no 5, p. 533-540Article in journal (Refereed)
    Abstract [en]

    Lipoprotein lipase (LPL) hydrolyzes lipids in plasma lipoproteins so that the fatty acids can be taken up and used by cells. The activity of LPL changes rapidly in response to changes in nutrition, physical activity and other conditions. Angiopoietin-like protein 4 (ANGPTL4) is an important controller of LPL activity. Both LPL and ANGPTL4 are produced and secreted by adipocytes. When the transcription blocker Actinomycin D was added to cultures of 3T3-L1 adipocytes, LPL activity in the medium increased several-fold. LPL mRNA decreased moderately during 5 h, while ANGPTL4 mRNA and protein declined rapidly, explaining that LPL activity was increased. TNF-alpha is known to reduce LPL activity in adipose tissue. We have shown that TNF-a increased ANGPTL4 both at the mRNA and protein level. Expression of ANGPTL4 is known to be under control of Foxol. Use of the Foxol-specific inhibitor AS1842856, or knockdown of ANGPTL4 by RNAi, resulted in increased LPL activity in the medium. Both with ActD and with the Foxol inhibitor the cells became unresponsive to TNF-a. This study shows that TNF-a, by a Foxol dependent pathway, increases the transcription of ANGPTL4 which is secreted by the cells and causes inactivation of LPL.

  • 93. Marchant, Alan
    et al.
    Bhalerao, Rishikesh
    Casimiro, Ilda
    Eklöf, Jan
    Department of Forest Genetics and Plant Physiology, The Swedish University of Agricultural Sciences, S-901 83, Umeå, Sweden.
    Casero, Pedro J
    Bennett, Malcolm
    Sandberg, Goran
    AUX1 promotes lateral root formation by facilitating indole-3-acetic acid distribution between sink and source tissues in the Arabidopsis seedling2002In: The Plant Cell, ISSN 1040-4651, E-ISSN 1532-298X, Vol. 14, no 3, p. 589-597Article in journal (Refereed)
    Abstract [en]

    Arabidopsis root architecture is regulated by shoot-derived signals such as nitrate and auxin. We report that mutations in the putative auxin influx carrier AUX1 modify root architecture as a result of the disruption in hormone transport between indole-3-acetic acid (IAA) source and sink tissues. Gas chromatography-selected reaction monitoring-mass spectrometry measurements revealed that the aux1 mutant exhibited altered IAA distribution in young leaf and root tissues, the major IAA source and sink organs, respectively, in the developing seedling. Expression studies using the auxin-inducible reporter IAA2::uidA revealed that AUX1 facilitates IAA loading into the leaf vascular transport system. AUX1 also facilitates IAA unloading in the primary root apex and developing lateral root primordium. Exogenous application of the synthetic auxin 1-naphthylacetic acid is able to rescue the aux1 lateral root phenotype, implying that root auxin levels are suboptimal for lateral root primordium initiation in the mutant.

  • 94.
    Marschinke, Franziska
    et al.
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Histology and Cell Biology.
    Hashemian, Sanaz Alsadat
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Histology and Cell Biology.
    Matozaki, Takashi
    Kobe University Graduate School of Medicine.
    Oldenborg, Per-Arne
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Histology and Cell Biology.
    Strömberg, Ingrid
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Histology and Cell Biology.
    The absence of CD47 promotes nerve fiber growth from cultured ventral mesencephalic dopamine neurons2012In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 7, no 9, p. e45218-Article in journal (Refereed)
    Abstract [en]

    In ventral mesencephalic organotypic tissue cultures, two timely separated sequences of nerve fiber growth have been observed. The first appearing nerve fiber pattern is a long-distance outgrowth that occurs before astrocytes start to proliferate and migrate to form an astrocytic monolayer that finally surrounds the tissue slice. These long-distance growing nerve fibers are retracted as the astrocytes migrate, and are followed by a secondary outgrowth. The secondary outgrowth is persistent in time but reaches short distances, comparable with outgrowth seen from a dopaminergic graft implanted to the brain. The present study was focused on the interaction between the astrocytes and the long-distance growing non-glial associated nerve fibers. Cross talk between astroglia and neurite formation might occur through the integrin-associated protein CD47. CD47 serves as a ligand for signal regulatory protein (SIRP) alpha and as a receptor for the extracellular matrix protein thrombospondin-1 (TSP-1). Embryonic day 14 ventral mesencephalic tissue from CD47(+/+) and CD47(-/-) mice was used to investigate astrocytic migration and the tyrosine hydroxylase (TH) -positive outgrowth that occurred remote from the astrocytes. TH-immunohistochemistry demonstrated that the non-glial-associated nerve fiber outgrowth in CD47(-/-) cultures reached significantly longer distances and higher density compared to nerve fibers formed in CD47(+/+) cultures at 14 days in vitro. These nerve fibers often had a dotted appearance in CD47(+/+) cultures. No difference in the astrocytic migration was observed. Further investigations revealed that the presence of CD47 in control culture did neither hamper non-glial-associated growth through SIRP alpha nor through TSP-1 since similar outgrowth was found in SIRP alpha mutant cultures and in CD47(+/+) cultures treated with blocking antibodies against the TSP-1, respectively, as in the control cultures. In conclusion, long-distance growing nerve fiber formation is promoted by the absence of CD47, even though the presence of astrocytes is not inhibited.

  • 95. Miller, Shyra J
    et al.
    Li, Hongzhen
    Rizvi, Tilat A
    Huang, Yuan
    Johansson, Gunnar
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Oncology. Umeå University.
    Bowersock, Jason
    Sidani, Amer
    Vitullo, John
    Vogel, Kristine
    Parysek, Linda M
    DeClue, Jeffrey E
    Ratner, Nancy
    Brain lipid binding protein in axon-Schwann cell interactions and peripheral nerve tumorigenesis.2003In: Molecular and Cellular Biology, ISSN 0270-7306, E-ISSN 1098-5549, Vol. 23, no 6, p. 2213-24Article in journal (Refereed)
    Abstract [en]

    Loss of axonal contact characterizes Schwann cells in benign and malignant peripheral nerve sheath tumors (MPNST) from neurofibromatosis type 1 (NF1) patients. Tumor Schwann cells demonstrate NF1 mutations, elevated Ras activity, and aberrant epidermal growth factor receptor (EGFR) expression. Using cDNA microarrays, we found that brain lipid binding protein (BLBP) is elevated in an EGFR-positive subpopulation of Nf1 mutant mouse Schwann cells (Nf1(-/-) TXF) that grows away from axons; BLBP expression was not affected by farnesyltransferase inhibitor, an inhibitor of H-Ras. BLBP was also detected in EGFR-positive cell lines derived from Nf1:p53 double mutant mice and human MPNST. BLBP expression was induced in normal Schwann cells following transfection with EGFR but not H-Ras12V. Furthermore, EGFR-mediated BLBP expression was not inhibited by dominant-negative H-Ras, indicating that BLBP expression is downstream of Ras-independent EGFR signaling. BLBP-blocking antibodies enabled process outgrowth from Nf1(-/-) TXF cells and restored interaction with axons, without affecting cell proliferation or migration. Following injury, BLBP expression was induced in normal sciatic nerves when nonmyelinating Schwann cells remodeled their processes. These data suggest that BLBP, stimulated by Ras-independent pathways, regulates Schwann cell-axon interactions in normal peripheral nerve and peripheral nerve tumors.

  • 96.
    Mincheva-Nilsson, Lucia
    et al.
    Umeå University, Faculty of Medicine, Department of Clinical Microbiology, Clinical Immunology.
    Baranov, Vladimir
    Umeå University, Faculty of Medicine, Department of Clinical Microbiology, Clinical Immunology.
    Yeung, M M
    Hammarström, Sten
    Umeå University, Faculty of Medicine, Department of Clinical Microbiology, Immunology/Immunchemistry.
    Hammarström, Marie-Louise
    Umeå University, Faculty of Medicine, Department of Clinical Microbiology, Immunology/Immunchemistry.
    Immunomorphologic studies of human decidua-associated lymphoid cells in normal early pregnancy.1994In: Journal of Immunology, ISSN 0022-1767, E-ISSN 1550-6606, Vol. 152, no 4, p. 2020-32Article in journal (Refereed)
    Abstract [en]

    Human decidual lymphocytes from early, normal pregnancy were characterized in situ with respect to ultrastructure and distribution of subsets. The ultrastructure of isolated decidual gamma delta T cells was also studied. CD45+ cells comprised 11 +/- 2% of all decidual cells. The majority were localized in large lymphoid cell clusters (LCC), near endometrial glands, or as intraepithelial lymphocytes (IEL) in glandular epithelium. The major cell populations in LCC were CD56+TCR-gamma delta+ cells, CD56+ cells, TCR-alpha beta+CD4+ cells, and TCR-alpha beta+CD8+ cells. All expressed activation markers (CD45RO, Kp43, and/or HML-1) and MHC class II Ag (HLA-DR, HLA-DP, and/or HLA-DQ). No B cells were found. Almost all IEL were activated TCR-gamma delta+ cells (CD56+ and CD56-). The glandular epithelial cells expressed heat shock protein 60 at the basolateral side facing the TCR-gamma delta+ IEL. Decidual lymphocytes displayed cytoplasmic processes, microvilli, characteristic cytoplasmic granules, and had intimate contact with neighboring cells. Lymphocytes in the outer rim of LCC and the stroma showed signs of cellular movement. Two main morphotypes of gamma delta T cells could be distinguished. One had single microvilli, membrane-bound granules, and nuclear inclusions. The other had many microvilli, nonmembrane-bound granules and cytoplasmic multivesicular bodies. Our data suggest that LCC are centers of immune reactivity where T and NK cells become activated. The activated cells may guard against infections and undue trophoblast invasion and/or be involved in modulating the local maternal immune system toward unresponsiveness against the semiallogeneic fetus.

  • 97. Minina, E. A.
    et al.
    Coll, N. S.
    Tuominen, Hannele
    Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC). Umeå University, Faculty of Science and Technology, Department of Plant Physiology.
    Bozhkov, P. V.
    Metacaspases versus caspases in development and cell fate regulation2017In: Cell Death and Differentiation, ISSN 1350-9047, E-ISSN 1476-5403, Vol. 24, no 8, p. 1314-1325Article, review/survey (Refereed)
    Abstract [en]

    Initially found to be critically involved in inflammation and apoptosis, caspases have since then been implicated in the regulation of various signaling pathways in animals. How caspases and caspase-mediated processes evolved is a topic of great interest and hot debate. In fact, caspases are just the tip of the iceberg, representing a relatively small group of mostly animal-specific enzymes within a broad family of structurally related cysteine proteases (family C14 of CD clan) found in all kingdoms of life. Apart from caspases, this family encompasses para-and metacaspases, and all three groups of proteases exhibit significant variation in biochemistry and function in vivo. Notably, metacaspases are present in all eukaryotic lineages with a remarkable absence in animals. Thus, metacaspases and caspases must have adapted to operate under distinct cellular and physiological settings. Here we discuss biochemical properties and biological functions of metacaspases in comparison to caspases, with a major focus on the regulation of developmental aspects in plants versus animals.

  • 98. Morell, M. L.
    et al.
    Pena Carcamo, J. R.
    Vazquez, C. A.
    Vatansever, S.
    Upadhyay, Arunkumar S.
    Umeå University, Faculty of Medicine, Department of Clinical Microbiology. Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS).
    Overby, A. K.
    Cordo, S. M.
    Garcia, C. C.
    Viperin exerts antiviral function against Junin mammarenavirus at different subcellular localizations2017In: Molecular Biology of the Cell, ISSN 1059-1524, E-ISSN 1939-4586, Vol. 28Article in journal (Other academic)
  • 99. Moren, Bjorn
    et al.
    Hansson, Bjorn
    Negoita, Florentina
    Fryklund, Claes
    Lundmark, Richard
    Umeå University, Faculty of Medicine, Department of Medical Biochemistry and Biophysics.
    Goransson, Olga
    Stenkula, Karin G.
    EHD2 regulates adipocyte function and is enriched at cell surface-associated lipid droplets in primary human adipocytes2019In: Molecular Biology of the Cell, ISSN 1059-1524, E-ISSN 1939-4586, Vol. 30, no 10, p. 1147-1159Article in journal (Refereed)
    Abstract [en]

    Adipocytes play a central role in energy balance, and dysfunctional adipose tissue severely affects systemic energy homeostasis. The ATPase EH domain-containing 2 (EHD2) has previously been shown to regulate caveolae, plasma membrane-specific domains that are involved in lipid uptake and signal transduction. Here, we investigated the role of EHD2 in adipocyte function. We demonstrate that EHD2 protein expression is highly up-regulated at the onset of triglyceride accumulation during adipocyte differentiation. Small interfering RNA-mediated EHD2 silencing affected the differentiation process and impaired insulin sensitivity, lipid storage capacity, and lipolysis. Fluorescence imaging revealed localization of EHD2 to caveolae, close to cell surface-associated lipid droplets in primary human adipocytes. These lipid droplets stained positive for glycerol transporter aquaporin 7 and phosphorylated perilipin-1 following adrenergic stimulation. Further, EHD2 overexpression in human adipocytes increased the lipolytic signaling and suppressed the activity of transcription factor PPAR.. Overall, these data suggest that EHD2 plays a key role for adipocyte function.

  • 100. Mork-Jansson, Astrid Elisabeth
    et al.
    Gargano, Daniela
    Kmiec, Karol
    Fumes, Clemens
    Shevela, Dmitriy
    Umeå University, Faculty of Science and Technology, Department of Chemistry. Center for Organelle Research, University of Stavanger, Stavanger, Norway.
    Eichacker, Lutz Andreas
    Lil3 dimerization and chlorophyll binding in Arabidopsis thaliana2015In: FEBS Letters, ISSN 0014-5793, E-ISSN 1873-3468, Vol. 589, no 20, p. 3064-3070Article in journal (Refereed)
    Abstract [en]

    The two-helix light harvesting like (Lil) protein Lil3 belongs to the family of chlorophyll binding light harvesting proteins of photosynthetic membranes. A function in tetrapyrrol synthesis and stabilization of geranylgeraniol reductase has been shown. Lil proteins contain the chlorophyll a/b-binding motif; however, binding of chlorophyll has not been demonstrated. We find that Lil3.2 from Arabidopsis thaliana forms heterodimers with Lil3.1 and binds chlorophyll. Lil3.2 heterodimerization (25 +/- 7.8 nM) is favored relative to homodimerization (431 +/- 59 nM). Interaction of Lil3.2 with chlorophyll a (231 +/- 49 nM) suggests that heterodimerization precedes binding of chlorophyll in Arabidopsis thatiana. 

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