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  • 151.
    Bröms, Jeanette
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för molekylärbiologi (Teknisk-naturvetenskaplig fakultet). Department of Medical Countermeasures, Swedish Defence Research Agency.
    Forslund, Anna-Lena
    Department of Medical Countermeasures, Swedish Defence Research Agency.
    Forsberg, Åke
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för molekylärbiologi (Teknisk-naturvetenskaplig fakultet). Umeå universitet, Medicinska fakulteten, Institutionen för molekylärbiologi (Medicinska fakulteten). Department of Medical Countermeasures, Swedish Defence Research Agency.
    Francis, Matthew
    Umeå universitet, Medicinska fakulteten, Institutionen för molekylärbiologi (Medicinska fakulteten). Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för molekylärbiologi (Teknisk-naturvetenskaplig fakultet).
    PcrH of Pseudomonas aeruginosa is essential for secretion and assembly of the type III translocon2003Ingår i: Journal of Infectious Diseases, ISSN 0022-1899, E-ISSN 1537-6613, Vol. 188, nr 12, s. 1909-1921Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Pseudomonas aeruginosa harbors a type III secretion system that translocates antihost effectors into an infected eukaryotic cell. PcrH is a key component of type III secretion in this essential virulence strategy. In the absence of PcrH, P. aeruginosa is translocation deficient because of a specific reduction in presecretory stability and subsequent secretion of PopB and PopD, 2 proteins essential for the translocation process. PcrH exerts this chaperone function by binding directly to PopB and PopD. Consistent with the genetic relatedness of PcrH with LcrH of pathogenic Yersinia species, these proteins are functionally interchangeable with respect to their ability to complement the translocation defect associated with either a lcrH or pcrH null mutant, respectively. Thus, the translocator class of chaperones performs a critical function in ensuring the assembly of a translocation competent type III secreton. Finally, unlike the regulatory roles of other translocator-class chaperones (e.g., LcrH, SicA of Salmonella enterica, and IpgC of Shigella species), in vitro regulation of P. aeruginosa type III secretion does not involve PcrH.

  • 152.
    Bröms, Jeanette
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för molekylärbiologi (Teknisk-naturvetenskaplig fakultet).
    Sundin, Charlotta
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för molekylärbiologi (Teknisk-naturvetenskaplig fakultet).
    Francis, Matthew
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för molekylärbiologi (Teknisk-naturvetenskaplig fakultet). Umeå universitet, Medicinska fakulteten, Institutionen för molekylärbiologi (Medicinska fakulteten).
    Forsberg, Åke
    Umeå universitet, Medicinska fakulteten, Institutionen för molekylärbiologi (Medicinska fakulteten). Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för molekylärbiologi (Teknisk-naturvetenskaplig fakultet).
    Comparative analysis of type III effector translocation by Yersinia pseudotuberculosis expressing native LcrV or PcrV from Pseudomonas aeruginosa2003Ingår i: Journal of Infectious Diseases, ISSN 0022-1899, E-ISSN 1537-6613, Vol. 188, nr 2, s. 239-249Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The homologues LcrV of Yersinia species and PcrV of Pseudomonas aeruginosa are pore-forming components. When expressed in a Yersinia lcrV background, PcrV formed smaller pores in infected erythrocyte membranes, correlating to a lowered translocation of Yersinia effectors. To understand this phenomenon, cytotoxins exoenzyme S of P. aeruginosa and YopE of Yersinia were introduced into a Yersinia background without Yop effectors but expressing LcrV or PcrV. Comparable translocation of each substrate indicated that substrate recognition by LcrV/PcrV is not a regulator of translocation. Yersinia harboring pcrV coexpressed with its native operon efficiently translocated effectors into HeLa cell monolayers and formed large LcrV-like pores in erythrocyte membranes. Thus, a PcrV complex with native P. aeruginosa translocon components is required to form fully functional pores for complete complementation of effector translocation in Yersinia.

  • 153. Buchan, J Ross
    et al.
    Nissan, Tracy
    Umeå universitet, Medicinska fakulteten, Institutionen för molekylärbiologi (Medicinska fakulteten).
    Parker, Roy
    Analyzing p-bodies and stress granules in Saccharomyces cerevisae2010Ingår i: Guide to yeast genetics: functional genomics, proteomics, and other systems analysis / [ed] Jonathan Weissman, Christine Guthrie, Gerald R. Fink, San Diego: Academic Press, 2010, 2, Vol. 470, s. 619-640Kapitel i bok, del av antologi (Refereegranskat)
    Abstract [en]

    Eukaryotic cells contain at least two types of cytoplasmic RNA protein (RNP) granules that contain nontranslating mRNAs. One such RNP granule is a P-body, which contains translationally inactive mRNAs and proteins involved in mRNA degradation and translation repression. A second such RNP granule is a stress granule which also contains mRNAs, some RNA binding proteins and several translation initiation factors, suggesting these granules contain mRNAs stalled in translation initiation. In this chapter, we describe methods to analyze P-bodies and stress granules in Saccharomyces cerevisiae, including procedures to determine if a protein or mRNA can accumulate in either granule, if an environmental perturbation or mutation affects granule size and number, and granule quantification methods.

  • 154.
    Bueno, Emilio
    et al.
    Umeå universitet, Medicinska fakulteten, Molekylär Infektionsmedicin, Sverige (MIMS). Umeå universitet, Medicinska fakulteten, Institutionen för molekylärbiologi (Medicinska fakulteten). CSIC, Estac Expt Zaidin, Dept Soil Microbiol & Symbiot Syst, C Profesor Albareda 1, E-18008 Granada, Spain.
    Robles, Eloy F.
    Torres, Maria J.
    Krell, Tino
    Bedmar, Eulogio J.
    Delgado, Maria J.
    Mesa, Socorro
    Disparate response to microoxia and nitrogen oxides of the Bradyrhizobium japonicum napEDABC, nirK and norCBQD denitrification genes2017Ingår i: Nitric oxide, ISSN 1089-8603, E-ISSN 1089-8611, Vol. 68, s. 137-149Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Expression of the Bradyrhizobium japonicum napEDABC, nirK and norCBQD denitrification genes requires low oxygen (O-2) tension and nitrate (NO3), through a regulatory network comprised of two coordinated cascades, FixLJ-FixK(2)-NnrR and RegSR-NifA. To precisely understand how these signals are integrated in the FixLJ-FixK(2)-NnrR circuit, we analyzed beta-Galactosidase activities from napE-lacZ, nirK-lacZ and norC-lacZ fusions, and performed analyses of NapC and NorC levels as well as periplasmic nitrate reductase (Nap) activity, in B. japonicum wildtype and fixK(2) and nnrR mutant backgrounds. While microoxic conditions (2% O-2 at headspace) were sufficient to induce expression of napEDABC and nirK genes and this control depends on FixK(2), norCBQD expression requires, in addition to microoxia, nitric oxide gas (NO) and both FixK(2) and NnrR transcription factors. Purified FixK(2) protein directly interacted and activated transcription in collaboration with B. japonicum RNA polymerase (RNAP) from the napEDABC and nirK promoters, but not from the norCBQD promoter. Further, recombinant NnrR protein bound exclusively to the norCBQD promoter in an O-2-sensitive manner. Our work suggest a disparate regulation of B. japonicum denitrifying genes expression with regard to their dependency to microoxia, nitrogen oxides (NOx), and the regulatory proteins FixK(2) and NnrR. In this control, expression of napEDABC and nirK genes requires microoxic conditions and directly depends on FixK2, while expression of norCBQD genes relies on NO, being NnrR the candidate which directly interacts with the norCBQD promoter. 

  • 155.
    Bueno, Emilio
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för molekylärbiologi (Medicinska fakulteten). Umeå universitet, Medicinska fakulteten, Molekylär Infektionsmedicin, Sverige (MIMS).
    Sit, Brandon
    Waldor, Matthew K.
    Cava, Felipe
    Umeå universitet, Medicinska fakulteten, Molekylär Infektionsmedicin, Sverige (MIMS). Umeå universitet, Medicinska fakulteten, Institutionen för molekylärbiologi (Medicinska fakulteten).
    Anaerobic nitrate reduction divergently governs population expansion of the enteropathogen Vibrio cholerae2018Ingår i: Nature Microbiology, E-ISSN 2058-5276, Vol. 3, nr 12, s. 1346-1353Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    To survive and proliferate in the absence of oxygen, many enteric pathogens can undergo anaerobic respiration within the host by using nitrate (NO3-) as an electron acceptor(1,2). In these bacteria, NO3- is typically reduced by a nitrate reductase to nitrite (NO2-), a toxic intermediate that is further reduced by a nitrite reductase(3). However, Vibrio cholerae, the intestinal pathogen that causes cholera, lacks a nitrite reductase, leading to NO2- accumulation during nitrate reduction 4(.) Thus, V. cholerae is thought to be unable to undergo NO3-(-)dependent anaerobic respiration(4). Here, we show that during hypoxic growth, NO3- reduction in V. cholerae divergently affects bacterial fitness in a manner dependent on environmental pH. Remarkably, in alkaline conditions, V. cholerae can reduce NO3- to support population growth. Conversely, in acidic conditions, accumulation of NO2- from NO3- reduction simultaneously limits population expansion and preserves cell viability by lowering fermentative acid production. Interestingly, other bacterial species such as Salmonella typhimurium, enterohaemorrhagic Escherichia coli (EHEC) and Citrobacter rodentium also reproduced this pH-dependent response, suggesting that this mechanism might be conserved within enteric pathogens. Our findings explain how a bacterial pathogen can use a single redox reaction to divergently regulate population expansion depending on the fluctuating environmental pH.

  • 156.
    Bugaytsova, Jeanna
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk kemi och biofysik.
    Chernov, Yevgen A
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk kemi och biofysik.
    Gideonsson, Pär
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk kemi och biofysik.
    Mendez, Melissa
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk kemi och biofysik.
    Henriksson, Sara
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk kemi och biofysik. Umeå universitet, Medicinska fakulteten, Institutionen för molekylärbiologi (Medicinska fakulteten).
    Mahdavi, Jafar
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk kemi och biofysik. School of Life Sciences, CBS, University of Nottingham, Nottingham, UK..
    Quintana-Hayashi, Macarena
    Department of Biochemistry and Cell biology, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden..
    Shevtsova, Anna
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk kemi och biofysik.
    Sjöström, Rolf
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk kemi och biofysik.
    Moskalenko, Roman
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk kemi och biofysik. Department of Pathology, Medical Institute, State University, Sumy, Ukraine.
    Aisenbrey, Christopher
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen. Université de Strasbourg, Institut de Chimie, Strasbourg, France.
    Moonens, Kristof
    Structural and Molecular Microbiology, VIB Department of Structural Biology, Belgium.
    Björnham, Oscar
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik. FOI Totalförsvarets Forskningsinstitut, Umeå, Sweden..
    Brännström, Kristoffer
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk kemi och biofysik.
    Bylund, Göran
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk kemi och biofysik.
    Königer, Verena
    Max von Pettenkofer Institute of Hygiene and Medical Microbiology, LMU, Munich, Germany.
    Vikström, Susanne
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk kemi och biofysik.
    Schmidt, Alexej
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk kemi och biofysik. Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk biovetenskap.
    Rakhimova, Lena
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk kemi och biofysik.
    Hofer, Anders
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk kemi och biofysik.
    Ögren, Johan
    Umeå universitet, Medicinska fakulteten, Institutionen för odontologi.
    Ilver, Dag
    Department of Biochemistry and Cell biology, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden.
    Liu, Hui
    Department of Medicine, USUHS, Bethesda, MD, USA.
    Goldman, Matthew
    Department of Pediatrics, USUHS, Bethesda, MD, USA.
    Whitmire, Jeannette M
    Department of Microbiology and Immunology, USUHS, Bethesda, MD USA.
    Kelly, Charles G
    King's College London, Dental Institute, London, UK.
    Gilman, Robert H
    Department of International Health, John Hopkins School of Public Health, Baltimore, MD, USA.
    Chowdhury, Abhijit
    Centre for Liver Research, School of Digestive and Liver Diseases, Institute of Post Graduate Medical Education & Research, Kolkata, India.
    Mukhopadhyay, Asish K
    Division of Bacteriology, National Institute of Cholera and Enteric Diseases, Kolkata, India.
    Nair, Balakrish G
    Translational Health Science and Technology Institute, Haryana, India.
    Papadakos, Konstantinos S
    Hellenic Pasteur Institute, Athens, Greece.
    Martinez-Gonzalez, Beatriz
    Hellenic Pasteur Institute, Athens, Greece.
    Sgouras, Dionyssios N
    Hellenic Pasteur Institute, Athens, Greece.
    Engstrand, Lars
    Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, Stockholm, Sweden.
    Unemo, Magnus
    Department of Laboratory Medicine, Microbiology, Örebro University Hospital, Örebro, Sweden.
    Danielsson, Dan
    Department of Laboratory Medicine, Microbiology, Örebro University Hospital, Örebro, Sweden.
    Sebastian, Suerbaum
    Institute for Medical Microbiology and Hospital Epidemiology Hannover Medical School, Hannover, Germany.
    Oscarson, Stefan
    Centre for Synthesis and Chemical Biology, School of Chemistry, University College Dublin, Dublin, Ireland.
    Morozova-Roche, Ludmilla
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk kemi och biofysik.
    Gröbner, Gerhard
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Holgersson, Jan
    Department of Clinical Chemistry and Transfusion Medicine, Sahlgrenska Academy, University of Gothenburg, Sahlgrenska University Hospital, Gothenburg, Sweden.
    Strömberg, Nicklas
    Umeå universitet, Medicinska fakulteten, Institutionen för odontologi.
    Esberg, Anders
    Umeå universitet, Medicinska fakulteten, Institutionen för odontologi.
    Eldridge, Angela
    Department of Pathology and Laboratory Medicine, University of California Davis School of Medicine, Sacramento, CA, USA.
    Chromy, Brett A
    Department of Pathology and Laboratory Medicine, University of California Davis School of Medicine, Sacramento, CA, USA.
    Hansen, Lori
    Departments of Medical Microbiology and Immunology, Center for Comparative Medicine, University of California Davis, Davis, CA, USA.
    Solnick, Jay
    Departments of Medical Microbiology and Immunology, Center for Comparative Medicine, University of California Davis, Davis, CA, USA.
    Haas, Rainer
    Max von Pettenkofer Institute of Hygiene and Medical Microbiology, LMU Munich, Munich, Germany.
    Schedin, Staffan
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Lindén, Sara K
    Department of Biochemistry and Cell biology, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden.
    Dubois, Andre
    Department of Medicine, USUHS, Bethesda, MD, USA.
    Merrell, D. Scott
    Department of Microbiology and Immunology, USUHS, Bethesda, MD, USA.
    Remaut, Han
    Structural and Molecular Microbiology, VIB Department of Structural Biology, VIB, Brussels, Belgium.
    Arnqvist, Anna
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk kemi och biofysik.
    Berg, Douglas E
    Department of Medicine, University of California San Diego, La Jolla, CA, USA.
    Borén, Thomas
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk kemi och biofysik.
    Acid Responsive Helicobacter pylori Adherence: Implications for Chronic Infection and DiseaseManuskript (preprint) (Övrigt vetenskapligt)
  • 157.
    Bunikis, Ignas
    Umeå universitet, Medicinsk fakultet, Molekylärbiologi (Medicinska fakulteten).
    Borrelia channel-forming proteins: structure and function2010Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Borrelia is a Gram-negative, corkscrew-shaped bacterium transmitted by infected ticks or lice. Borreliae are subdivided into pathogens of two diseases: Lyme disease, caused mainly by B. burgdorferi, B. afzelii and B. garinii; and relapsing fever caused primarily by B. duttonii, B. hermsii, B. recurrentis or B. crocidurae. Both diseases differ in their manifestations, duration times and dissemination patterns. Antibiotics are the major therapeutics, although unfortunately antibiotic treatment is not always beneficial. To date, drug resistance mechanisms in B. burgdorferi are unknown. Transporters of the resistance-nodulation-division (RND) family appear to be involved in drug resistance, especially in Gram-negative bacteria. They consist of three components: a cytoplasmic membrane export system, a membrane fusion protein (MFP), and an outer membrane factor (OMP). The major antibiotic efflux activity of this type in Escherichia coli is mediated by the tripartite multidrug resistance pump AcrAB-TolC. Based on the sequence homology we conclude that the besA (bb0140), besB (bb0141) and besC (bb0142) genes code for a similar efflux system in B. burgdorferi. We created a deletion mutant of besC. The minimal inhibitory concentration (MIC) values of B. burgdorferi carrying an inactive besC gene were 4- to 8-fold lower than in the wild type strain. Animal experiments showed that the besC mutant was unable to infect mice. Black lipid bilayer experiments were carried out to determine the biophysical properties of purified BesC. This study showed the importance of BesC protein for B. burgdorferi pathogenicity and resistance to antibiotics, although its importance in clinical isolates is not known.

    Due to its small genome, Borrelia is metabolically and biosynthetically deficient, thereby making it highly dependent on nutrients provided by their hosts. The uptake of nutrients by Borrelia is not yet completely understood. We describe the purification and characterization of a 36-kDa protein that functions as a putative dicarboxylate-specific porin in the outer membrane of Borrelia. The protein was designated as DipA, for dicarboxylate-specific porin A. DipA was biophysically characterized using the black lipid bilayer assay. The permeation of KCl through the channel could be partly blocked by titrating the DipA-mediated membrane conductance with increasing concentrations of different organic dicarboxylic anions. The obtained results imply that DipA does not form a general diffusion pore, but a porin with a binding site specific for dicarboxylates which play important key roles in the deficient metabolic and biosynthetic pathways of Borrelia species.

    The presence of porin P66 has been shown in both Lyme disease and relapsing fever spirochetes. In our study, purified P66 homologues from Lyme disease species B. burgdorferi, B. afzelii and B. garinii and relapsing fever species B. duttonii, B. recurrentis and B. hermsii were compared and their biophysical properties were further characterized in black lipid bilayer assay. Subsequently, the channel diameter of B. burgdorferi P66 was investigated in more detail. For this study, different nonelectrolytes with known hydrodynamic radii were used. This allowed us to determine the effective diameter of the P66 channel lumen. Furthermore, the blockage of the channel after addition of nonelectrolytes revealed seven subconducting states and indicated a heptameric structure of the P66 channel. These results may give more insight into the functional properties of this important porin.

  • 158.
    Bunikis, Ignas
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för molekylärbiologi (Medicinska fakulteten).
    Bonde, Mari
    Umeå universitet, Medicinska fakulteten, Institutionen för molekylärbiologi (Medicinska fakulteten).
    Kutschan-Bunikis, Sabrina
    Umeå universitet, Medicinska fakulteten, Institutionen för molekylärbiologi (Medicinska fakulteten).
    Bergström, Sven
    Umeå universitet, Medicinska fakulteten, Institutionen för molekylärbiologi (Medicinska fakulteten).
    Multiplex PCR as a tool for validating plasmid content of Borrelia burgdorferi.2011Ingår i: Journal of Microbiological Methods, ISSN 0167-7012, E-ISSN 1872-8359, Vol. 86, nr 2, s. 243-7Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Borrelia burgdorferi has an unusual genomic structure containing 21 plasmids. These plasmids carry genes that are essential for infectivity and survival of the spirochetes in vivo. Several plasmids are lost during cultivation in vitro, which might lead to a heterogeneous population after multiple passages and loss of infectivity in laboratory animals. Herein, we present a simple and inexpensive multiplex PCR method that detects the complete plasmid profile of B. burgdorferi B31 in just two PCR tubes.

  • 159.
    Bunikis, Ignas
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för molekylärbiologi (Medicinska fakulteten).
    Denker, Katrin
    Östberg, Yngve
    Umeå universitet, Medicinska fakulteten, Institutionen för molekylärbiologi (Medicinska fakulteten).
    Andersen, Christian
    Benz, Roland
    Bergström, Sven
    Umeå universitet, Medicinska fakulteten, Institutionen för molekylärbiologi (Medicinska fakulteten).
    An RND-type efflux system in Borrelia burgdorferi is involved in virulence and resistance to antimicrobial compounds2008Ingår i: PLoS Pathogenicity, ISSN 1553-7374, Vol. 4, nr 2, s. e1000009-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Borrelia burgdorferi is remarkable for its ability to thrive in widely different environments due to its ability to infect various organisms. In comparison to enteric Gram-negative bacteria, these spirochetes have only a few transmembrane proteins some of which are thought to play a role in solute and nutrient uptake and excretion of toxic substances. Here, we have identified an outer membrane protein, BesC, which is part of a putative export system comprising the components BesA, BesB and BesC. We show that BesC, a TolC homolog, forms channels in planar lipid bilayers and is involved in antibiotic resistance. A besC knockout was unable to establish infection in mice, signifying the importance of this outer membrane channel in the mammalian host. The biophysical properties of BesC could be explained by a model based on the channel-tunnel structure. We have also generated a structural model of the efflux apparatus showing the putative spatial orientation of BesC with respect to the AcrAB homologs BesAB. We believe that our findings will be helpful in unraveling the pathogenic mechanisms of borreliae as well as in developing novel therapeutic agents aiming to block the function of this secretion apparatus.

  • 160. Bunikis, J
    et al.
    Noppa, L
    Östberg, Yngve
    Umeå universitet, Medicinska fakulteten, Institutionen för molekylärbiologi (Medicinska fakulteten).
    Barbour, A G
    Bergström, Sven
    Umeå universitet, Medicinska fakulteten, Institutionen för molekylärbiologi (Medicinska fakulteten).
    Surface exposure and species specificity of an immunoreactive domain of a 66-kilodalton outer membrane protein (P66) of the Borrelia spp. that cause Lyme disease1996Ingår i: Infection and Immunity, ISSN 0019-9567, E-ISSN 1098-5522, Vol. 64, nr 12, s. 5111-5116Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A chromosomally encoded 66-kDa protein (P66) of Borrelia spp. that cause Lyme disease has previously been shown to be associated with the spirochetal outer membrane. A topological model of P66 predicts a surface-exposed fragment which links the N- and C-terminal intramembranous domains of the protein (J. Bunikis, L. Noppa, and S. Bergström, FEMS Microbiol. Lett. 131:139-145, 1995). In the present study, an immunogenic determinant of P66 was identified by a comparison of the immunoreactivities of different fragments of P66 generated either by proteolytic treatment of intact spirochetes or as recombinant proteins expressed in Escherichia coli. The immune response to P66 during natural infection was found to be directed against the predicted surface domain which comprises amino acids at positions 454 through 491. A sequence comparison revealed considerable polymorphism of the surface domains of P66 proteins of different Lyme disease-causing Borrelia species. Five sequence patterns of this domain were observed in the B. garinii strains studied. In contrast, sequences of the relevant part of P66 of the B. afzelii and B. burgdorferi sensu stricto isolates studied were identical within the respective species. In immunoblotting, 5 of 17 (29.4%) sera from North American patients with early disseminated or persistent Lyme disease reacted against P66 of B. burgdorferi sensu stricto B31. These sera, however, failed to recognize P66 of B. afzelii and B. garinii, as well as an analog of P66 in the relapsing fever agent, B. hermsii. In conclusion, the topological model of P66 is supported by the demonstration of an apparent surface localization of an immunoreactive domain of this protein. Furthermore, analogous to the plasmid-encoded borrelial outer surface proteins, the predicted surface-exposed portion of chromosomally encoded P66 appears to be antigenically heterogenous.

  • 161.
    Buren, Jonas
    et al.
    Umeå universitet, Medicinsk fakultet, Folkhälsa och klinisk medicin, Medicin.
    Bergström, Sven-Anders
    Umeå universitet, Medicinsk fakultet, Folkhälsa och klinisk medicin, Medicin.
    Loh, Edmund
    Umeå universitet, Medicinsk fakultet, Molekylärbiologi (Medicinska fakulteten).
    Söderström, Ingegerd
    Umeå universitet, Medicinsk fakultet, Folkhälsa och klinisk medicin, Medicin.
    Olsson, Tommy
    Umeå universitet, Medicinsk fakultet, Folkhälsa och klinisk medicin, Medicin.
    Mattsson, Cecilia
    Umeå universitet, Medicinsk fakultet, Folkhälsa och klinisk medicin, Medicin.
    Hippocampal 11beta-hydroxysteroid dehydrogenase type 1 messenger ribonucleic acid expression has a diurnal variability that is lost in the obese Zucker rat.2007Ingår i: Endocrinology, ISSN 0013-7227, Vol. 148, nr 6, s. 2716-22Artikel i tidskrift (Refereegranskat)
  • 162. Buus, Terkild Brink
    et al.
    Willerslev-Olsen, Andreas
    Fredholm, Simon
    Blumel, Edda
    Nastasi, Claudia
    Gluud, Maria
    Hu, Tengpeng
    Lindahl, Lise M.
    Iversen, Lars
    Fogh, Hanne
    Gniadecki, Robert
    Litvinov, Ivan V.
    Persson, Jenny L.
    Umeå universitet, Medicinska fakulteten, Institutionen för molekylärbiologi (Medicinska fakulteten). Clinical Research Center, Lund University, Malmö, Sweden.
    Bonefeld, Charlotte Menne
    Geisler, Carsten
    Christensen, Jan Praysgaard
    Krejsgaard, Thorbjorn
    Litman, Thomas
    Woetmann, Anders
    Odum, Niels
    Single-cell heterogeneity in Sézary syndrome2018Ingår i: Blood Advances, ISSN 2473-9529, Vol. 2, nr 16, s. 2115-2126Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Sezary syndrome (SS) is an aggressive leukemic variant of cutaneous T-cell lymphoma (CTCL) with a median life expectancy of less than 4 years. Although initial treatment responses are often good, the vast majority of patients with SS fail to respond to ongoing therapy. We hypothesize that malignant T cells are highly heterogeneous and harbor subpopulations of SS cells that are both sensitive and resistant to treatment. Here, we investigate the presence of single-cell heterogeneity and resistance to histone deacetylase inhibitors (HDACi) within primary malignant T cells from patients with SS. Using single-cell RNA sequencing and flow cytometry, we find that malignant T cells from all investigated patients with SS display a high degree of single-cell heterogeneity at both the mRNA and protein levels. We show that this heterogeneity divides the malignant cells into distinct subpopulations that can be isolated by their expression of different surface antigens. Finally, we show that treatment with HDACi (suberanilohydroxamic acid and romidepsin) selectively eliminates some subpopulations while leaving other subpopulations largely unaffected. In conclusion, we show that patients with SS display a high degree of single-cell heterogeneity within the malignant T-cell population, and that distinct subpopulations of malignant T cells carry HDACi resistance. Our data point to the importance of understanding the heterogeneous nature of malignant SS cells in each individual patient to design combinational and new therapies to counter drug resistance and treatment failure.

  • 163. Bárcena-Uribarri, Iván
    et al.
    Thein, Marcus
    Barbot, Mariam
    Sans-Serramitjana, Eulalia
    Bonde, Mari
    Umeå universitet, Medicinska fakulteten, Institutionen för molekylärbiologi (Medicinska fakulteten).
    Mentele, Reinhard
    Lottspeich, Friedrich
    Bergström, Sven
    Umeå universitet, Medicinska fakulteten, Institutionen för molekylärbiologi (Medicinska fakulteten).
    Benz, Roland
    Study of the protein complex, pore diameter, and pore-forming activity of the Borrelia burgdorferi P13 porin2014Ingår i: Journal of Biological Chemistry, ISSN 0021-9258, E-ISSN 1083-351X, Vol. 289, nr 27, s. 18614-18624Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    P13 is one of the major outer membrane proteins of Borrelia burgdorferi. Previous studies described P13 as a porin. In the present study some structure and function aspects of P13 were studied. P13 showed according to lipid bilayer studies a channel-forming activity of 0.6 nanosiemens in 1 M KCl. Single channel and selectivity measurements demonstrated that P13 had no preference for either cations or anions and showed no voltage-gating up to +/-100 mV. Blue native polyacrylamide gel electrophoresis was used to isolate and characterize the P13 protein complex in its native state. The complex had a high molecular mass of about 300 kDa and was only composed of P13 monomers. The channel size was investigated using non-electrolytes revealing an apparent diameter of about 1.4 nm with a 400-Da molecular mass cut-off. Multichannel titrations with different substrates reinforced the idea that P13 forms a general diffusion channel. The identity of P13 within the complex was confirmed by second dimension SDS-PAGE, Western blotting, mass spectrometry, and the use of a p13 deletion mutant strain. The results suggested that P13 is the protein responsible for the 0.6-nanosiemens pore-forming activity in the outer membrane of B. burgdorferi.

  • 164.
    Bárcena-Uribarri, Iván
    et al.
    Universität Würzburg, Germany.
    Thein, Marcus
    Universität Würzburg and Jacobs University Bremen, Germany.
    Maier, Elke
    Universität Würzburg, Germany.
    Bonde, Mari
    Umeå universitet, Medicinska fakulteten, Institutionen för molekylärbiologi (Medicinska fakulteten).
    Bunikis, Ignas
    Umeå universitet, Medicinska fakulteten, Institutionen för molekylärbiologi (Medicinska fakulteten).
    Bergström, Sven
    Umeå universitet, Medicinska fakulteten, Institutionen för molekylärbiologi (Medicinska fakulteten).
    Benz, Roland
    Universität Würzburg, Germany.
    Use of nonelectrolytes reveals the channel size and oligomeric constitution of the Borrelia burgdorferi P66 porinManuskript (preprint) (Övrigt vetenskapligt)
    Abstract [en]

    The outer membrane protein P66 of the Lyme disease spirochete Borrelia burgdorferi is capable of pore formation with an atypical high single-channel conductance of 11 nS in 1 M KCl. We studied in a non-theoretical manner the diameter of the P66 channel by analyzing its single-channel conductance in black lipid bilayers in the presence of different nonelectrolytes with known hydrodynamic radii. Furthermore, we calculated the filling of the channel with these nonelectrolytes and the results revealed that nonelectrolytes with hydrodynamic radii of 0.34 nm or smaller pass through the pore, whereas neutral molecules with greater radii only partially filled the channel or were not able to enter it at all. Thus, the diameter of the P66 entrance was determined to be ≤ 1.9 nm with a constriction site diameter of about 0.7 nm. Furthermore, the P66-induced membrane conductance could be blocked by 80-90% after addition of the nonelectrolytes PEG 400, PEG 600 and maltohexaose in the low millimolar range. Interestingly, the analysis of the power density spectra of P66 after blockage with nonelectrolytes revealed no chemical interaction responsible for channel block. The blockage of one P66 single-channel conductance unit of 11 nS occurred by seven subconducting states, thus indicating a heptameric organization of the P66 oligomer. This organization of P66 as a heptamer was confirmed by Blue Native PAGE and immunoblot analysis, which demonstrated that P66 forms a complex with a mass of approximately 460 kDa.

  • 165.
    Bárcena-Uribarri, Iván
    et al.
    University of Würzburg.
    Thein, Marcus
    Max Planck Institute for Developmental Biology.
    Sacher, Anna
    German Cancer Research Center.
    Bunikis, Ignas
    Umeå universitet, Medicinska fakulteten, Institutionen för molekylärbiologi (Medicinska fakulteten).
    Bonde, Mari
    Umeå universitet, Medicinska fakulteten, Institutionen för molekylärbiologi (Medicinska fakulteten).
    Bergström, Sven
    Umeå universitet, Medicinska fakulteten, Institutionen för molekylärbiologi (Medicinska fakulteten).
    Benz, Roland
    University of Würzburg.
    P66 porins are present in both Lyme disease and relapsing fever spirochetes: a comparison of the biophysical properties of P66 porins from six Borrelia species2010Ingår i: Biochimica et Biophysica Acta - Biomembranes, ISSN 0005-2736, E-ISSN 1879-2642, Vol. 1798, nr 6, s. 1197-1203Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The genus Borrelia is the cause of the two human diseases: Lyme disease (LD) and relapsing fever (RF). BothLD and RF Borrelia species are obligate parasites and are dependent on nutrients provided by their hosts. Thefirst step of nutrient uptake across the outer membrane of these Gram-negative bacteria is accomplished bywater-filled channels, so-called porins. The knowledge of the porin composition in the outer membranes ofthe different pathogenic Borrelia species is limited. Only one porin has been described in relapsing feverspirochetes to date, whereas four porins are known to be present in Lyme disease agents. From these, theBorrelia burgdorferi outer membrane channel P66 is known to act as an adhesin and was well studied as aporin. To investigate if P66 porins are expressed and similarly capable of pore formation in other Borreliacausing Lyme disease or relapsing fever three LD species (B. burgdorferi, B. afzelii, B. garinii) and three RFspecies (B. duttonii, B. recurrentis and B. hermsii) were investigated for outer membrane proteins homologousto P66. A search in current published RF genomes, comprising the ones of B. duttonii, B. recurrentis and B.hermsii, indicated that they all contained P66 homologues. The P66 homologues of the six Borrelia specieswere purified to homogeneity and their pore-forming abilities as well as the biophysical properties of thepores were analyzed using the black lipid bilayer assay.

  • 166.
    Bäckström, Stefan
    et al.
    Umeå universitet, Teknisk-naturvetenskaplig fakultet, Umeå centrum för molekylär patogenes (UCMP) (Teknisk-naturvetenskaplig fakultet).
    Huang, Shenghua
    Umeå universitet, Teknisk-naturvetenskaplig fakultet, Umeå centrum för molekylär patogenes (UCMP) (Teknisk-naturvetenskaplig fakultet).
    Wolf-Watz, Magnus
    Kemi.
    Xie, X Q
    Medicinsk fakultet, Molekylärbiologi (Medicinska fakulteten).
    Härd, Torleif
    Grundström, Thomas
    Medicinsk fakultet, Molekylärbiologi (Medicinska fakulteten).
    Sauer, Uwe
    Umeå universitet, Teknisk-naturvetenskaplig fakultet, Umeå centrum för molekylär patogenes (UCMP) (Teknisk-naturvetenskaplig fakultet).
    Crystallization and preliminary studies of the DNA-binding runt domain of AML1.2001Ingår i: Acta Crystallogr D Biol Crystallogr, ISSN 0907-4449, Vol. 57, nr Pt 2, s. 269-71Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The acute myeloid leukaemia 1 (AML1) protein belongs to the Runx family of transcription factors and is crucial for haematopoietic development. The genes encoding Runx1 and its associated factor CBF beta are the most frequent targets for chromosomal rearrangements in acute human leukaemias. In addition, point mutations of Runx1 in acute leukaemias and in the familial platelet disorder FPD/AML cluster within the evolutionary conserved runt domain that binds both DNA and CBF beta. Here, the crystallization of the Runx1 runt domain is reported. Crystals belong to space groups C2 and R32 and diffract to 1.7 and 2.0 A resolution, respectively.

  • 167.
    Bäckström, Stefan
    et al.
    Umeå universitet, Teknisk-naturvetenskaplig fakultet, Umeå centrum för molekylär patogenes (UCMP) (Teknisk-naturvetenskaplig fakultet).
    Wolf-Watz, Magnus
    Kemi.
    Grundström, Christine
    Medicinsk fakultet, Molekylärbiologi (Medicinska fakulteten).
    Härd, Torleif
    Grundström, Thomas
    Medicinsk fakultet, Molekylärbiologi (Medicinska fakulteten).
    Sauer, Uwe
    Umeå universitet, Teknisk-naturvetenskaplig fakultet, Umeå centrum för molekylär patogenes (UCMP) (Teknisk-naturvetenskaplig fakultet).
    The RUNX1 Runt domain at 1.25A resolution: a structural switch and specifically bound chloride ions modulate DNA binding.2002Ingår i: J Mol Biol, ISSN 0022-2836, Vol. 322, nr 2, s. 259-72Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The evolutionarily conserved Runt homology domain is characteristic of the RUNX family of heterodimeric eukaryotic transcription factors, including RUNX1, RUNX2 and RUNX3. The genes for RUNX1, also termed acute myeloid leukemia protein 1, AML1, and its dimerization partner core-binding factor beta, CBFbeta, are essential for hematopoietic development and are together the most common targets for gene rearrangements in acute human leukemias. Here, we describe the crystal structure of the uncomplexed RUNX1 Runt domain at 1.25A resolution and compare its conformation to previously published structures in complex with DNA, CBFbeta or both. We find that complex formation induces significant structural rearrangements in this immunoglobulin (Ig)-like DNA-binding domain. Most pronounced is the movement of loop L11, which changes from a closed conformation in the free Runt structure to an open conformation in the CBFbeta-bound and DNA-bound forms. This transition, which we refer to as the S-switch, and accompanying structural movements that affect other parts of the Runt domain are crucial for sustained DNA binding. The closed to open transition can be induced by CBFbeta alone; suggesting that one role of CBFbeta is to trigger the S-switch and to stabilize the Runt domain in a conformation enhanced for DNA binding.A feature of the Runt domain hitherto unobserved in any Ig-like DNA-binding domain is the presence of two specifically bound chloride ions. One chloride ion is coordinated by amino acid residues that make direct DNA contact. In a series of electrophoretic mobility-shift analyses, we demonstrate a chloride ion concentration-dependent stimulation of the DNA-binding activity of Runt in the physiological range. A comparable DNA-binding stimulation was observed for negatively charged amino acid residues. This suggests a regulatory mechanism of RUNX proteins through acidic amino acid residues provided by activation domains during cooperative interaction with other transcription factors.

  • 168.
    Bäreclev, Caroline
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för molekylärbiologi (Medicinska fakulteten). Umeå universitet, Medicinska fakulteten, Umeå Centre for Microbial Research (UCMR).
    Vaitkevicius, Karolis
    Umeå universitet, Medicinska fakulteten, Institutionen för molekylärbiologi (Medicinska fakulteten). Umeå universitet, Medicinska fakulteten, Umeå Centre for Microbial Research (UCMR).
    Netterling, Sakura
    Umeå universitet, Medicinska fakulteten, Institutionen för molekylärbiologi (Medicinska fakulteten). Umeå universitet, Medicinska fakulteten, Umeå Centre for Microbial Research (UCMR).
    Johansson, Jörgen
    DExD-box RNA-helicases in Listeria monocytogenes are important for growth, ribosomal maturation, rRNA processing and virulence factor expression2014Ingår i: RNA Biology, ISSN 1547-6286, E-ISSN 1555-8584, Vol. 11, nr 11, s. 1458-1467Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    RNA-helicases are proteins required for the unwinding of occluding secondary RNA structures, especially at low temperatures. In this work, we have deleted all 4 DExD-box RNA helicases in various combinations in the Gram-positive pathogen Listeria monocytogenes. Our results show that 3 out of 4 RNA-helicases were important for growth at low temperatures, whereas the effect was less prominent at 37 degrees C. Over-expression of one RNA-helicase, Lmo1450, was able to overcome the reduced growth of the quadruple mutant strain at temperatures above 26 degrees C, but not at lower temperatures. The maturation of ribosomes was affected in different degrees in the various strains at 20 degrees C, whereas the effect was marginal at 37 degrees C. This was accompanied by an increased level of immature 23S rRNA precursors in some of the RNA-helicase mutants at low temperatures. Although the expression of the PrfA regulated virulence factors ActA and LLO decreased in the quadruple mutant strain, this strain showed a slightly increased infection ability. Interestingly, even though the level of the virulence factor LLO was decreased in the quadruple mutant strain as compared with the wild-type strain, the hly-transcript (encoding LLO) was increased. Hence, our results could suggest a role for the RNA-helicases during translation. In this work, we show that DExD-box RNA-helicases are involved in bacterial virulence gene-expression and infection of eukaryotic cells.

  • 169.
    Cameron, Sarina R.
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för molekylärbiologi (Medicinska fakulteten).
    Nandi, Soumyadeep
    Umeå universitet, Medicinska fakulteten, Institutionen för molekylärbiologi (Medicinska fakulteten).
    Kahn, Tatyana G.
    Umeå universitet, Medicinska fakulteten, Institutionen för molekylärbiologi (Medicinska fakulteten).
    Barrasa, Juan I.
    Umeå universitet, Medicinska fakulteten, Institutionen för molekylärbiologi (Medicinska fakulteten).
    Stenberg, Per
    Umeå universitet, Medicinska fakulteten, Institutionen för molekylärbiologi (Medicinska fakulteten). Division of Chemical, Biological, Radioactive and Nuclear (CBRN) Security and Defence, FOI–Swedish Defence Research Agency, 906 21 Umeå Sweden.
    Schwartz, Yuri B.
    Umeå universitet, Medicinska fakulteten, Institutionen för molekylärbiologi (Medicinska fakulteten).
    PTE, a novel module to target Polycomb Repressive Complex 1 to the human cyclin D2 (CCND2) oncogene2018Ingår i: Journal of Biological Chemistry, ISSN 0021-9258, E-ISSN 1083-351X, Vol. 293, nr 37, s. 14342-14358Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Polycomb group proteins are essential epigenetic repressors. They form multiple protein complexes of which two kinds, PRC1 and PRC2, are indispensable for repression. Although much is known about their biochemical properties, how mammalian PRC1 and PRC2 are targeted to specific genes is poorly understood. Here, we establish the cyclin D2 (CCND2) oncogene as a simple model to address this question. We provide the evidence that the targeting of PRC1 to CCND2 involves a dedicated PRC1-targeting element (PTE). The PTE appears to act in concert with an adjacent cytosine-phosphate-guanine (CpG) island to arrange for the robust binding of PRC1 and PRC2 to repressed CCND2. Our findings pave the way to identify sequence-specific DNA-binding proteins implicated in the targeting of mammalian PRC1 complexes and provide novel link between polycomb repression and cancer.

  • 170.
    Carlsson, Anna
    et al.
    Umeå universitet, Medicinska fakulteten, Umeå centrum för molekylär medicin (UCMM).
    Forsgren, Lars
    Umeå universitet, Medicinska fakulteten, Institutionen för farmakologi och klinisk neurovetenskap, Klinisk neurovetenskap.
    Nylander, P-O
    Hellman, Urban
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk biovetenskap, Medicinsk och klinisk genetik.
    Forsman-Semb, Kristina
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk biovetenskap, Medicinsk och klinisk genetik.
    Holmgren, Gösta
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk biovetenskap, Medicinsk och klinisk genetik.
    Holmberg, Dan
    Umeå universitet, Medicinska fakulteten, Umeå centrum för molekylär medicin (UCMM).
    Holmberg, Monica
    Umeå universitet, Medicinska fakulteten, Institutionen för molekylärbiologi (Medicinska fakulteten).
    Identification of a susceptibility locus for migraine with and without aura on 6p12.2-p21.1.2002Ingår i: Neurology, ISSN 0028-3878, E-ISSN 1526-632X, Vol. 59, nr 11, s. 1804-1807Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Migraine is the most common type of chronic episodic headache. To find novel susceptibility genes for familial migraine with and without aura, a genomewide screen was performed in a large family from northern Sweden. Evidence of linkage was obtained on chromosome 6p12.2-p21.1, with a maximum two-point lod score of 5.41 for marker D6S452. The patients with migraine shared a common haplotype of 10 Mb between markers D6S1650 and D6S1960.

  • 171.
    Carlsson, Katrin E
    et al.
    Umeå universitet, Teknisk-naturvetenskaplig fakultet, Molekylärbiologi (Teknisk-naturvetenskaplig fakultet).
    Liu, Junfa
    Umeå universitet, Teknisk-naturvetenskaplig fakultet, Molekylärbiologi (Teknisk-naturvetenskaplig fakultet).
    Edqvist, Petra J
    Umeå universitet, Medicinsk fakultet, Molekylärbiologi (Medicinska fakulteten).
    Francis, Matthew S
    Umeå universitet, Teknisk-naturvetenskaplig fakultet, Molekylärbiologi (Teknisk-naturvetenskaplig fakultet). Umeå universitet, Medicinsk fakultet, Umeå Centre for Microbial Research (UCMR).
    Extracytoplasmic-stress-responsive pathways modulate type III secretion in Yersinia pseudotuberculosis.2007Ingår i: Infect Immun, ISSN 0019-9567, Vol. 75, nr 8, s. 3913-24Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Three signal transduction pathways, the two-component systems CpxRA and BaeSR and the alternative sigma factor sigma(E), respond to extracytoplasmic stress that facilitates bacterial adaptation to changing environments. At least the CpxRA and sigma(E) pathways control the production of protein-folding and degradation factors that counter the effects of protein misfolding in the periplasm. This function also influences the biogenesis of multicomponent extracellular appendages that span the bacterial envelope, such as various forms of pili. Herein, we investigated whether any of these regulatory pathways in the enteropathogen Yersinia pseudotuberculosis affect the functionality of the Ysc-Yop type III secretion system. This is a multicomponent molecular syringe spanning the bacterial envelope used to inject effector proteins directly into eukaryotic cells. Disruption of individual components revealed that the Cpx and sigma(E) pathways are important for Y. pseudotuberculosis type III secretion of Yops (Yersinia outer proteins). In particular, a loss of CpxA, a sensor kinase, reduced levels of structural Ysc (Yersinia secretion) components in bacterial membranes, suggesting that these mutant bacteria are less able to assemble a functional secretion apparatus. Moreover, these bacteria were no longer capable of localizing Yops into the eukaryotic cell interior. In addition, a cpxA lcrQ double mutant engineered to overproduce and secrete Yops was still impaired in intoxicating cells. Thus, the Cpx pathway might mediate multiple influences on bacterium-target cell contact that modulate Yersinia type III secretion-dependent host cell cytotoxicity.

  • 172.
    Carlsson, Katrin E
    et al.
    Umeå universitet, Teknisk-naturvetenskaplig fakultet, Molekylärbiologi (Teknisk-naturvetenskaplig fakultet).
    Liu, Junfa
    Umeå universitet, Teknisk-naturvetenskaplig fakultet, Molekylärbiologi (Teknisk-naturvetenskaplig fakultet).
    Edqvist, Petra J
    Umeå universitet, Medicinsk fakultet, Molekylärbiologi (Medicinska fakulteten).
    Francis, Matthew S
    Umeå universitet, Teknisk-naturvetenskaplig fakultet, Molekylärbiologi (Teknisk-naturvetenskaplig fakultet). Umeå universitet, Medicinsk fakultet, Umeå Centre for Microbial Research (UCMR).
    Influence of the Cpx extracytoplasmic-stress-responsive pathway on Yersinia sp.-eukaryotic cell contact.2007Ingår i: Infect Immun, ISSN 0019-9567, Vol. 75, nr 9, s. 4386-99Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The extracytoplasmic-stress-responsive CpxRA two-component signal transduction pathway allows bacteria to adapt to growth in extreme environments. It controls the production of periplasmic protein folding and degradation factors, which aids in the biogenesis of multicomponent virulence determinants that span the bacterial envelope. This is true of the Yersinia pseudotuberculosis Ysc-Yop type III secretion system. However, despite using a second-site suppressor mutation to restore Yop effector secretion by yersiniae defective in the CpxA sensor kinase, these bacteria poorly translocated Yops into target eukaryotic cells. Investigation of this phenotype herein revealed that the expression of genes which encode several surface-located adhesins is also influenced by the Cpx pathway. In particular, the expression and surface localization of invasin, an adhesin that engages beta1-integrins on the eukaryotic cell surface, are severely restricted by the removal of CpxA. This reduces bacterial association with eukaryotic cells, which could be suppressed by the ectopic production of CpxA, invasin, or RovA, a positive activator of inv expression. In turn, these infected eukaryotic cells then became susceptible to intoxication by translocated Yop effectors. In contrast, bacteria harboring an in-frame deletion of cpxR, which encodes the cognate response regulator, displayed an enhanced ability to interact with cell monolayers, as well as elevated inv and rovA transcription. This phenotype could be drastically suppressed by providing a wild-type copy of cpxR in trans. We propose a mechanism of inv regulation influenced by the direct negative effects of phosphorylated CpxR on inv and rovA transcription. In this fashion, sensing of extracytoplasmic stress by CpxAR contributes to productive Yersinia sp.-eukaryotic cell interactions.

  • 173.
    Carlsson, Lennart
    Umeå universitet, Medicinska fakulteten, Institutionen för molekylärbiologi (Medicinska fakulteten).
    Aspects of interferon alpha signalling in hematopoetic cells2004Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    The type I interferons (IFN) are a family of cytokines with pleiothropic activities that include inhibition of viral replication, cell proliferation and activation of the immune system. These properties give the IFNs important physiological and pathological roles in infection and cancer and have led to their therapeutic use for many clinical conditions. In humans, the type I IFNs consist of 12 different IFNa subtypes as well as single IFNb, w and k subtypes. They all compete for binding to a common receptor, consisting of two subunits, IFNAR1 and IFNAR2. In almost all cell types proliferation is inhibited by IFNs as a consequence of the antiviral properties. However, previous studies on human peripheral B-lymphocytes have shown increased survival as well as proliferation upon IFN treatment.

    We established a purification system for extraction of B-lymphocytes from buffy-coat, utilizing density centrifugation in combination with anti-CD19 magnetic beads. In an attempt to identify the molecular mechanisms of increased survival, the expression and/or activation pattern of different signaling proteins were analysed by Western blot. It was previously reported that phosphatidylinositol 3’-kinase (PI3K) physically interacts with the IFNAR complex, via adaptor proteins. Activated PI3K indirectly activates Akt/PKB, a kinase involved in a pathway leading to both survival and proliferation signals. We were able to show a novel signaling pathway - IFN treatment activated Akt/PKB as well as a downstream effector, one member of the Forkhead family (FKHR) was inactivated by phosphorylation and as a consequence p27/Kip1 expression was downregulated. Activation of this pathway resulted in increased survival as measured by TUNEL assay, an effect efficiently counteracted by the the synthetic PI3K inhibitor, LY294002.

    In additional experiments we investigated the molecular mechanisms of proliferation. Activation of B-cells was ensured by using limiting concentrations of anti-IgM antibodies, mimicing natural activation. Using thymidine incorporation, we discovered that IFN treatment increased the sensitivity to anti-IgM stimulation. As a consequence, more cells proliferated as measured by CFSE staining. However, on its own, IFN was unable to induce proliferation. IFN turned out to be as efficient as IL-2, a classical B-lymphocyte growth factor. In order to distinguish proliferation from increased survival, Rb phoshorylation was analysed by Western blot. Phosphorylation induced by anti-IgM was further enhanced by IFN. As we determined earlier, p27/Kip1 expression was downregulated, releasing the cell cycle block. However, p21/Cip1 expression was upregulated but almost exclusively localised to the cytoplasm, therefore unable to perform the classical growth inhibitory functions. We conclude that type I interferons contribute to increased survival as well as proliferation of human primary B-lymphocytes.

    The IFN receptor subunits was studied in a human myeloma cell line (U266), using a variant of which that are totally resistant towards the anti-proliferative properties of IFN. The reason for resistance in clinical situations is seldom elucidated, but is often believed to be due to development of antibodies against interferon. The resistant cells were unable to bind radio-labelled IFN, and through Southern Blot we could determine that the IFNAR1 gene was not functional. Also the IFNAR2 gene was affected, since Northern blot and sequencing detected an aberrant transcript not present in the wild type cells. Karyotyping showed that the cells had 3-4 copies of chromosome 21, but Southern blot did not detect any cytoplasmic region of IFNAR2. The IFN receptors are close to each other on the genome, and a deletion affecting one receptor gene is likely to affect the other as well. We conclude that the IFN resistance in U266Res cells is due to lack of functional receptor subunits.

  • 174.
    Carlsson, Lennart
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för molekylärbiologi (Medicinska fakulteten).
    Dacklin, Ingrid
    Persson, Håkan
    Golovleva, Irina
    Ruuth, Kristina
    Lundgren, Erik
    Characterisation of IFN resistance in a myeloma cell line with an unstable genomeManuskript (preprint) (Övrigt vetenskapligt)
  • 175.
    Carlsson, Lennart
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för molekylärbiologi (Medicinska fakulteten).
    Ruuth, Kristina
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för molekylärbiologi (Teknisk-naturvetenskaplig fakultet).
    Lundgren, Erik
    Umeå universitet, Medicinska fakulteten, Institutionen för molekylärbiologi (Medicinska fakulteten).
    IFN-alpha induced proliferation of human primary B-lymphocytesManuskript (preprint) (Övrigt vetenskapligt)
  • 176.
    Castelain, Mickaël
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Ehlers, Sarah
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Klinth, Jeanna
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Lindberg, Stina
    Umeå universitet, Medicinska fakulteten, Institutionen för molekylärbiologi (Medicinska fakulteten).
    Andersson, Magnus
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Uhlin, Bernt Eric
    Umeå universitet, Medicinska fakulteten, Institutionen för molekylärbiologi (Medicinska fakulteten).
    Axner, Ove
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Fast uncoiling kinetics of F1C pili expressed by uropathogenic Escherichia coli are revealed on a single pilus level using force-measuring optical tweezers2011Ingår i: European Biophysics Journal, ISSN 0175-7571, E-ISSN 1432-1017, Vol. 40, nr 3, s. 305-316Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Uropathogenic Escherichia coli (UPEC) expressvarious kinds of organelles, so-called pili or fimbriae, thatmediate adhesion to host tissue in the urinary tract throughspecific receptor-adhesin interactions. The biomechanicalproperties of these pili have been considered important forthe ability of bacteria to withstand shear forces from rinsingurine flows. Force-measuring optical tweezers have beenused to characterize individual organelles of F1C typeexpressed by UPEC bacteria with respect to such properties.Qualitatively, the force-versus-elongation response wasfound to be similar to that of other types of helix-like piliexpressed by UPEC, i.e., type 1, P, and S, with force-inducedelongation in three regions, one of which represents theimportant uncoiling mechanism of the helix-like quaternarystructure. Quantitatively, the steady-state uncoiling forcewas assessed as 26.4 ±1.4 pN, which is similar to those ofother pili (which range from 21 pN for SI to 30 pN for type 1).The corner velocity for dynamic response (1,400 nm/s) wasfound to be larger than those of the other pili (400–700 nm/sfor S and P pili, and 6 nm/s for type 1). The kinetics werefound to be faster, with a thermal opening rate of 17 Hz, afew times higher than S and P pili, and three orders ofmagnitude higher than type 1. These data suggest that F1Cpili are, like P and S pili, evolutionarily selected to primarilywithstand the conditions expressed in the upper urinary tract.

  • 177.
    Castelain, Mickaël
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Sjöström, Annika E
    Umeå universitet, Medicinska fakulteten, Institutionen för molekylärbiologi (Medicinska fakulteten).
    Fällman, Erik
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Uhlin, Bernt Eric
    Umeå universitet, Medicinska fakulteten, Institutionen för molekylärbiologi (Medicinska fakulteten).
    Andersson, Magnus
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Unfolding and refolding properties of S pili on extraintestinal pathogenic Escherichia coli2010Ingår i: European Biophysics Journal, ISSN 0175-7571, E-ISSN 1432-1017, Vol. 39, nr 8, s. 1105-1115Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    S pili are members of the chaperone-usher-pathway-assembled pili family that are predominantly associated with neonatal meningitis (S(II)) and believed to play a role in ascending urinary tract infections (S(I)). We used force-measuring optical tweezers to characterize the intrinsic biomechanical properties and kinetics of S(II) and S(I) pili. Under steady-state conditions, a sequential unfolding of the layers in the helix-like rod occurred at somewhat different forces, 26 pN for S(II) pili and 21 pN for S(I) pili, and there was an apparent difference in the kinetics, 1.3 and 8.8 Hz. Tests with bacteria defective in a newly recognized sfa gene (sfaX (II)) indicated that absence of the sfaX (II) gene weakens the interactions of the fimbrium slightly and decreases the kinetics. Data of S(I) are compared with those of previously assessed pili primary associated with urinary tract infections, the P and type 1 pili. S pili have weaker layer-to-layer bonds than both P and type 1 pili, 21, 28 and 30 pN, respectively. In addition, the S pili kinetics are ~10 times faster than the kinetics of P pili and ~550 times faster than the kinetics of type 1 pili. Our results also show that the biomechanical properties of pili expressed ectopically from a plasmid in a laboratory strain (HB101) and pili expressed from the chromosome of a clinical isolate (IHE3034) are identical. Moreover, we demonstrate that it is possible to distinguish, by analyzing force-extension data, the different types of pili expressed by an individual cell of a clinical bacterial isolate.

  • 178.
    Cava, Felipe
    Umeå universitet, Medicinska fakulteten, Molekylär Infektionsmedicin, Sverige (MIMS). Umeå universitet, Medicinska fakulteten, Institutionen för molekylärbiologi (Medicinska fakulteten).
    Biology of Vibrio cholerae: editorial overview2017Ingår i: International Microbiology, ISSN 1139-6709, E-ISSN 1618-1905, Vol. 20, nr 3Artikel i tidskrift (Övrigt vetenskapligt)
  • 179.
    Cava, Felipe
    Umeå universitet, Medicinska fakulteten, Molekylär Infektionsmedicin, Sverige (MIMS). Umeå universitet, Medicinska fakulteten, Institutionen för molekylärbiologi (Medicinska fakulteten).
    Divergent functional roles of D-amino acids secreted by Vibrio cholerae2017Ingår i: International Microbiology, ISSN 1139-6709, E-ISSN 1618-1905, Vol. 20, nr 3, s. 149-150Artikel, forskningsöversikt (Refereegranskat)
    Abstract [en]

    The L-forms of amino acids are used in all kingdoms of life to synthesize proteins. However, the bacterium Vibrio cholerae, the causative agent of cholera, produces D-amino acids which are released to the environment at millimolar concentrations. We baptized these D-amino acids as non-canonical D-amino acids (NCDAAs) since they are different from those (i.e. D-alanine and D-glutamate) normally present in the bacterial cell wall. In V. cholerae, production of NCDAAs relies on the BsrV enzyme, a periplasmic broad spectrum racemase. BsrV multispecific activity, produces of a wide range of distinct D-amino acids. Using a combination of genetics and molecular physiology approaches we have demonstrated that NCDAAs target different cellular processes which may function as part of a cooperative strategy in vibrio communities to protect non-producing members from competing bacteria. Because NCDAA production is widespread in bacteria, we anticipate that NCDAAs are relevant modulators of microbial subpopulations in diverse ecosystems.

  • 180.
    Cava, Felipe
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för molekylärbiologi (Medicinska fakulteten). Umeå universitet, Medicinska fakulteten, Umeå Centre for Microbial Research (UCMR). Umeå universitet, Medicinska fakulteten, Molekylär Infektionsmedicin, Sverige (MIMS).
    de Pedro, Miguel A.
    Peptidoglycan plasticity in bacteria: emerging variability of the murein sacculus and their associated biological functions2014Ingår i: Current Opinion in Microbiology, ISSN 1369-5274, E-ISSN 1879-0364, Vol. 18, s. 46-53Artikel, forskningsöversikt (Refereegranskat)
    Abstract [en]

    The peptidoglycan (PG) sacculus once thought to be just a reinforcing, static and uniform structure, is fast becoming recognized as a dynamic cell constituent involved in every aspect of bacterial physiology. Recent advances showed that in addition to 'classical' tasks - as an essential element to define bacterial shape, size, division and resistance to osmotic stress the sacculus plays very important roles in many other fields. The very few chemical and structural changes that were once considered as bizarre, or maybe exotic exceptions, are now universally accepted as fundamental pieces in bacterial cell wall adaptation to different kinds of environmental stresses; immune response; intra-specific and inter-specific signalling and antibiotics, just to mention a few. Most, if not all, of these implications are a consequence of the enormous adaptability of PG metabolism to cope with changing conditions, a characteristic for which the term plasticity is proposed. Here we overview and comment on a number of recent contributions on the cell wall adaptive responses to environmental challenges that has greatly impacted the already high complexity of the PG biology field. These new evidences have revived the interest in PG plasticity as an exciting and trendy topic in current microbiology which considers this variability as the trustworthy picture of bacterial PG in nature.

  • 181.
    Cava, Felipe
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för molekylärbiologi (Medicinska fakulteten). Umeå universitet, Medicinska fakulteten, Umeå Centre for Microbial Research (UCMR). Umeå universitet, Medicinska fakulteten, Molekylär Infektionsmedicin, Sverige (MIMS).
    Kuru, Erkin
    Brun, Yves V.
    de Pedro, Miguel A.
    Modes of cell wall growth differentiation in rod-shaped bacteria2013Ingår i: Current Opinion in Microbiology, ISSN 1369-5274, E-ISSN 1879-0364, Vol. 16, nr 6, s. 731-737Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A bacterial cell takes on the challenge to preserve and reproduce its shape at every generation against a substantial internal pressure by surrounding itself with a mechanical support, a peptidoglycan cell wall. The enlargement of the cell wall via net incorporation of precursors into the pre-existing wall conditions bacterial growth and morphology. However, generation, reproduction and/or modification of a specific shape requires that the incorporation takes place at precise locations for a defined time period. Much has been learnt in the past few years about the biochemistry of the peptidoglycan synthesis process, but topological approaches to the understanding of shape generation have been hindered by a lack of appropriate techniques. Recent technological advances are paving the way for substantial progress in understanding the mechanisms of bacterial morphogenesis. Here we review the latest developments, focusing on the impact of new techniques on the precise mapping of cell wall growth sites.

  • 182. Cavanagh, Jorunn Pauline
    et al.
    Pain, Maria
    Askarian, Fatemeh
    Bruun, Jack-Ansgar
    Urbarova, Ilona
    Wai, Sun Nyunt
    Umeå universitet, Medicinska fakulteten, Institutionen för molekylärbiologi (Medicinska fakulteten).
    Schrnidt, Frank
    Johannessen, Mona
    Comparative exoproteome profiling of an invasive and a commensal Staphylococcus haemolyticus isolate2019Ingår i: Journal of Proteomics, ISSN 1874-3919, E-ISSN 1876-7737, Vol. 197, s. 106-114Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Staphylococcus haemolyticus is a skin commensal emerging as an opportunistic pathogen. Nosocomial isolates of S. haemolyticus are the most antibiotic resistant members of the coagulase negative staphylococci (CoNS), but information about other S. haemolyticus virulence factors is scarce. Bacterial membrane vesicles (MVs) are one mediator of virulence by enabling secretion and long distance delivery of bacterial effector molecules while protecting the cargo from proteolytic degradation from the environment. We wanted to determine if the MV protein cargo of S. haemolyticus is strain specific and enriched in certain MV associated proteins compared to the totalsecretome.

    The present study shows that both clinical and commensal S. haemolyticus isolates produce membrane vesicles. The MV cargo of both strains was enriched in proteins involved in adhesion and acquisition of iron. The MV cargo of the clinical strain was further enriched in antimicrobial resistance proteins.

    Data are available via ProteomeXchange with identifier PXD010389.

    Biological significance: Clinical isolates of Staphylococcus haemolyticus are usually multidrug resistant, their main virulence factor is formation of biofilms, both factors leading to infections that are difficult to treat. We show that both clinical and commensal S. haemolyticusisolates produce membrane vesicles. Identification of staphylococcal membrane vesicles can potentially be used in novel approaches to combat staphylococcal infections, such as development of vaccines.

  • 183. Cerveny, Lukas
    et al.
    Straskova, Adela
    Dankova, Vera
    Hartlova, Anetta
    Umeå universitet, Medicinska fakulteten, Institutionen för molekylärbiologi (Medicinska fakulteten). Umeå universitet, Medicinska fakulteten, Molekylär Infektionsmedicin, Sverige (MIMS).
    Ceckova, Martina
    Staud, Frantisek
    Stulik, Jiri
    Tetratricopeptide Repeat Motifs in the World of Bacterial Pathogens: Role in Virulence Mechanisms2013Ingår i: Infection and Immunity, ISSN 0019-9567, E-ISSN 1098-5522, Vol. 81, nr 3, s. 629-635Artikel, forskningsöversikt (Refereegranskat)
    Abstract [en]

    The tetratricopeptide repeat (TPR) structural motif is known to occur in a wide variety of proteins present in prokaryotic and eukaryotic organisms. The TPR motif represents an elegant module for the assembly of various multiprotein complexes, and thus, TPR-containing proteins often play roles in vital cell processes. As the TPR profile is well defined, the complete TPR protein repertoire of a bacterium with a known genomic sequence can be predicted. This provides a tremendous opportunity for investigators to identify new TPR-containing proteins and study them in detail. In the past decade, TPR-containing proteins of bacterial pathogens have been reported to be directly related to virulence-associated functions. In this minireview, we summarize the current knowledge of the TPR-containing proteins involved in virulence mechanisms of bacterial pathogens while high-lighting the importance of TPR motifs for the proper functioning of class II chaperones of a type III secretion system in the pathogenesis of Yersinia, Pseudomonas, and Shigella.

  • 184. Chahlafi, Zahra
    et al.
    Alvarez, Laura
    Umeå universitet, Medicinska fakulteten, Institutionen för molekylärbiologi (Medicinska fakulteten).
    Cava, Felipe
    Umeå universitet, Medicinska fakulteten, Institutionen för molekylärbiologi (Medicinska fakulteten).
    Berenguer, José
    The role of conserved proteins DrpA and DrpB in nitrate respiration of Thermus thermophilus2018Ingår i: Environmental Microbiology, ISSN 1462-2912, E-ISSN 1462-2920, Vol. 20, nr 10, s. 3851-3861Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In many Thermus thermophilus strains, nitrate respiration is encoded in mobile genetic regions, along with regulatory circuits that modulate its expression based on anoxia and nitrate presence. The oxygen‐responsive system has been identified as the product of the dnrST (dnr) operon located immediately upstream of the nar operon (narCGHJIKT), which encodes the nitrate reductase (NR) and nitrate/nitrite transporters. In contrast, the nature of the nitrate sensory system is not known. Here, we analyse the putative nitrate‐sensing role of the bicistronic drp operon (drpAB) present downstream of the nar operon in most denitrifying Thermus spp. Expression of drp was found to depend on the master regulator DnrT, whereas the absence of DrpA or DrpB increased the expression of both DnrS and DnrT and, concomitantly, of the NR. Absence of both proteins made expression from the dnr and nar operons independent of nitrate. Polyclonal antisera allowed us to identify DrpA as a periplasmic protein and DrpB as a membrane protein, with capacity to bind to the cytoplasmic membrane. Here, we propose a role for DrpA/DrpB as nitrate sensors during denitrification.

  • 185.
    Chand, Damini
    Umeå universitet, Medicinska fakulteten, Institutionen för molekylärbiologi (Medicinska fakulteten).
    Mechanistic Implications and Characterization of Anaplastic Lymphoma Kinase (ALK) mutations in Neuroblastoma2015Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Anaplastic lymphoma kinase (ALK) is a receptor tyrosine kinase that was first reported as a fusion partner of nucleophosmin in Anaplastic large cell lymphoma in 1994. ALK is involved in myriad of cancers including neuroblastoma which is the most common extracranial solid tumor affecting young children. It arises in the neural crest cells of sympathetic nervous system origin and is responsible for 12% of all childhood cancer deaths. Several point mutations in ALK have been described in both familial and sporadic neuroblastoma.

    With the aim to understand the role of ALK in neuroblastoma further, we investigated the point mutations in ALK reported in patients. Using cell culture based methods and Drosophila as a model organism; we first characterized these mutations under three broad categories: 1) Ligand independent mutations that were constitutively active, 2) Kinase dead mutation and 3) Ligand dependent mutations that behaved as inducible wild type. Further, to understand the activation mechanism of ALK, we constructed mutations that could potentially alter ALK’s conformation based on the available crystal structure. From the data generated, we were able to provide a new perspective to the activation of full length ALK receptor. This was more in line with activation mechanism of insulin receptor and different from that suggested for ALK fusion protein. From a clinical point of view, all the mutations in the study were blocked to different degrees using the ALK inhibitor, crizotinib. Lastly, we identified potential downstream targets of ALK using phosphoproteomics. From the various targets identified, we focused on STAT3 and confirmed its role as a mediator in ALK initiated MYCN transcription. We showed that STAT3 inhibition led to reduction of MYCN levels and thereby identifying it as a potential therapeutic target in neuroblastoma. Overall, our study highlights clinical relevance of ALK mutations in neuroblastoma and from a basic biology viewpoint; it reveals important mechanistic insight into receptor activation.

  • 186.
    Chand, Damini
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för molekylärbiologi (Medicinska fakulteten).
    Yamazaki, Yasuo
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för molekylärbiologi (Teknisk-naturvetenskaplig fakultet).
    Ruuth, Kristina
    Umeå universitet, Medicinska fakulteten, Institutionen för molekylärbiologi (Medicinska fakulteten).
    Schönherr, Christina
    Umeå universitet, Medicinska fakulteten, Institutionen för molekylärbiologi (Medicinska fakulteten).
    Martinsson, Tommy
    Gothenburg, Sweden.
    Kogner, Per
    Stockholm, Sweden.
    Attiyeh, Edward F
    Philadelphia, PA 19104, USA .
    Maris, John
    Philadelphia, PA 19104, USA .
    Morozova, Olena
    Vancouver, British Columbia V5Z 4S6, Canada .
    Marra, Marco A
    Vancouver, British Columbia V5Z 4S6, Canada .
    Ohira, Miki
    Chiba 260-8717, Japan.
    Nakagawara, Akira
    Chiba 260-8717, Japan.
    Sandström, Per-Erik
    Umeå universitet, Medicinska fakulteten, Institutionen för klinisk vetenskap, Pediatrik.
    Palmer, Ruth H
    Umeå universitet, Medicinska fakulteten, Institutionen för molekylärbiologi (Medicinska fakulteten).
    Hallberg, Bengt
    Umeå universitet, Medicinska fakulteten, Institutionen för molekylärbiologi (Medicinska fakulteten).
    Cell culture and Drosophila model systems define three classes of anaplastic lymphoma kinase mutations in neuroblastoma2013Ingår i: Disease Models and Mechanisms, ISSN 1754-8403, E-ISSN 1754-8411, Vol. 6, nr 2, s. 373-382Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Neuroblastoma is a childhood extracranial solid tumor which is associated with a number of genetic changes. Included in these genetic alterations are mutations in the kinase domain of the Anaplastic Lymphoma Kinase (ALK) receptor tyrosine kinase (RTK), which have been found in both somatic and familial neuroblastoma. In order to treat patients accordingly required characterisation of these mutations in terms of their response to ALK tyrosine kinase inhibitors (TKIs). Here, we report the identification and characterisation of two novel neuroblastoma ALK mutations (A1099T and 1464STOP) which we have investigated together with several previously reported but uncharacterised ALK mutations (T1087I, D1091N, T1151M, M1166R, F1174I and A1234T). In order to understand the potential role of these ALK mutations in neuroblastoma progression we have employed cell culture based systems together with the model organism Drosophila as a readout for ligand-independent activity. Mutation of ALK at position F1174I generates a gain-of-function receptor capable of activating intracellular targets, such as ERK (extracellular signal regulated kinase) and STAT3 (signal transducer and activator of transcription 3) in a ligand independent manner. Analysis of these previously uncharacterised ALK mutants and comparison with ALK(F1174) mutants suggests that ALK mutations observed in neuroblastoma fall into three classes. These are: (i) gain-of-function ligand independent mutations such as ALK(F1174), (ii) kinase-dead ALK mutants, e.g. ALK(I1250T)(Schonherr et al 2011a) or (iii) ALK mutations which are ligand-dependent in nature. Irrespective of the nature of the observed ALK mutants, in every case the activity of the mutant ALK receptors could be abrogated by the ALK inhibitor crizotinib (PF-02341066, Xalkori), albeit with differing levels of sensitivity.

  • 187.
    Charpentier, Emmanuelle
    Umeå universitet, Medicinska fakulteten, Molekylär Infektionsmedicin, Sverige (MIMS). Umeå universitet, Medicinska fakulteten, Umeå Centre for Microbial Research (UCMR). Umeå universitet, Medicinska fakulteten, Institutionen för molekylärbiologi (Medicinska fakulteten). Department of Regulation in Infection Biology, Helmholtz Centre for Infection Research, Braunschweig, Germany; Hannover Medical School, Hannover, Germany.
    CRISPR-Cas9: how research on a bacterial RNA-guided mechanism opened new perspectives in biotechnology and biomedicine2015Ingår i: EMBO Molecular Medicine, ISSN 1757-4676, E-ISSN 1757-4684, Vol. 7, nr 4, s. 363-365Artikel i tidskrift (Refereegranskat)
  • 188.
    Charpentier, Emmanuelle
    Umeå universitet, Medicinska fakulteten, Molekylär Infektionsmedicin, Sverige (MIMS). Umeå universitet, Medicinska fakulteten, Umeå Centre for Microbial Research (UCMR). Umeå universitet, Medicinska fakulteten, Institutionen för molekylärbiologi (Medicinska fakulteten). Department of Regulation in Infection Biology, Max Planck Institute for Infection Biology, Berlin, Germany; Institute for Biology, Humboldt University, Berlin, Germany.
    Spotlight on... Emmanuelle Charpentier2018Ingår i: FEMS Microbiology Letters, ISSN 0378-1097, E-ISSN 1574-6968, Vol. 365, nr 4, artikel-id fnx271Artikel i tidskrift (Övrigt vetenskapligt)
  • 189.
    Charpentier, Emmanuelle
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för molekylärbiologi (Medicinska fakulteten).
    Marraffini, Luciano A.
    Editorial overview: Novel technologies in microbiology: Recent advances in techniques in microbiology2014Ingår i: Current Opinion in Microbiology, ISSN 1369-5274, E-ISSN 1879-0364, Vol. 19, s. VIII-XArtikel i tidskrift (Refereegranskat)
  • 190.
    Charpentier, Emmanuelle
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för molekylärbiologi (Medicinska fakulteten).
    Marraffini, Luciano A.
    Harnessing CRISPR-Cas9 immunity for genetic engineering2014Ingår i: Current Opinion in Microbiology, ISSN 1369-5274, E-ISSN 1879-0364, Vol. 19, s. 114-119Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    CRISPR-Cas encodes an adaptive immune system that defends prokaryotes against infectious viruses and plasmids. Immunity is mediated by Cas nucleases, which use small RNA guides (the crRNAs) to specify a cleavage site within the genome of invading nucleic acids. In type II CRISPR-Cas systems, the DNA-cleaving activity is performed by a single enzyme Cas9 guided by an RNA duplex. Using synthetic single RNA guides, Cas9 can be reprogrammed to create specific double-stranded DNA breaks in the genomes of a variety of organisms, ranging from human cells to bacteria, and thus constitutes a powerful tool for genetic engineering. Here we describe recent advancements in our understanding of type II CRISPR-Cas immunity and how these studies led to revolutionary genome editing applications.

  • 191.
    Charpentier, Emmanuelle
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för molekylärbiologi (Medicinska fakulteten). Umeå universitet, Medicinska fakulteten, Umeå Centre for Microbial Research (UCMR). Umeå universitet, Medicinska fakulteten, Molekylär Infektionsmedicin, Sverige (MIMS).
    Richter, Hagen
    van der Oost, John
    White, Malcolm F.
    Biogenesis pathways of RNA guides in archaeal and bacterial CRISPR-Cas adaptive immunity2015Ingår i: FEMS Microbiology Reviews, ISSN 0168-6445, E-ISSN 1574-6976, Vol. 39, nr 3, s. 428-441Artikel, forskningsöversikt (Refereegranskat)
    Abstract [en]

    CRISPR-Cas is an RNA-mediated adaptive immune system that defends bacteria and archaea against mobile genetic elements. Short mature CRISPR RNAs (crRNAs) are key elements in the interference step of the immune pathway. A CRISPR array composed of a series of repeats interspaced by spacer sequences acquired from invading mobile genomes is transcribed as a precursor crRNA (pre-crRNA) molecule. This pre-crRNA undergoes one or two maturation steps to generate the mature crRNAs that guide CRISPR-associated (Cas) protein(s) to cognate invading genomes for their destruction. Different types of CRISPR-Cas systems have evolved distinct crRNA biogenesis pathways that implicate highly sophisticated processing mechanisms. In Types I and III CRISPR-Cas systems, a specific endoribonuclease of the Cas6 family, either standalone or in a complex with other Cas proteins, cleaves the pre-crRNA within the repeat regions. In Type II systems, the trans-acting small RNA (tracrRNA) base pairs with each repeat of the pre-crRNA to form a dual-RNA that is cleaved by the housekeeping RNase III in the presence of the protein Cas9. In this review, we present a detailed comparative analysis of pre-crRNA recognition and cleavage mechanisms involved in the biogenesis of guide crRNAs in the three CRISPR-Cas types.

  • 192. Chauhan, Deepika
    et al.
    Srivastava, Pulkit Anupam
    Ritzl, Barbara
    Umeå universitet, Medicinska fakulteten, Institutionen för molekylärbiologi (Medicinska fakulteten). Umeå universitet, Medicinska fakulteten, Molekylär Infektionsmedicin, Sverige (MIMS). Umeå universitet, Medicinska fakulteten, Umeå Centre for Microbial Research (UCMR).
    Yennamalli, Ragothaman M.
    Cava, Felipe
    Umeå universitet, Medicinska fakulteten, Molekylär Infektionsmedicin, Sverige (MIMS). Umeå universitet, Medicinska fakulteten, Institutionen för molekylärbiologi (Medicinska fakulteten). Umeå universitet, Medicinska fakulteten, Umeå Centre for Microbial Research (UCMR).
    Priyadarshini, Richa
    Amino Acid-Dependent Alterations in Cell Wall and Cell Morphology of Deinococcus indicus DR12019Ingår i: Frontiers in Microbiology, ISSN 1664-302X, E-ISSN 1664-302X, Vol. 10, artikel-id 1449Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Deinococcus radiodurans exhibits growth medium-dependent morphological variation in cell shape, but there is no evidence whether this phenomenon is observed in other members of the Deinococcaceae family. In this study, we isolated a red-pigmented, aerobic, Deinococcus indicus strain DR1 from Dadri wetland, India. This D. indicus strain exhibited cell-morphology transition from rod-shaped cells to multi-cell chains in a growth-medium-dependent fashion. In response to addition of 1% casamino acids in the minimal growth medium, rod-shaped cells formed multi-cell chains. Addition of all 20 amino acids to the minimal medium was able to recapitulate the phenotype. Specifically, a combination of L-methionine, L-lysine, L-aspartate, and L-threonine caused morphological alterations. The transition from rod shape to multi-cell chains is due to delay in daughter cell separation after cell division. Minimal medium supplemented with L-ornithine alone was able to cause cell morphology changes. Furthermore, a comparative UPLC analysis of PG fragments isolated from D. indicus cells propagated in different growth media revealed alterations in the PG composition. An increase in the overall cross-linkage of PG was observed in muropeptides from nutrient-rich TSB and NB media versus PYE medium. Overall our study highlights that environmental conditions influence PG composition and cell morphology in D. indicus.

  • 193.
    Chen, Changchun
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för molekylärbiologi (Teknisk-naturvetenskaplig fakultet).
    Tuck, Simon
    Umeå universitet, Medicinska fakulteten, Umeå centrum för molekylär medicin (UCMM).
    Byström, Anders S
    Umeå universitet, Medicinska fakulteten, Institutionen för molekylärbiologi (Medicinska fakulteten).
    Defects in tRNA modification associated with neurological and developmental dysfunctions in Caenorhabditis elegans elongator mutants2009Ingår i: PLoS genetics, ISSN 1553-7404, Vol. 5, nr 7, s. e1000561-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Elongator is a six subunit protein complex, conserved from yeast to humans. Mutations in the human Elongator homologue, hELP1, are associated with the neurological disease familial dysautonomia. However, how Elongator functions in metazoans, and how the human mutations affect neural functions is incompletely understood. Here we show that in Caenorhabditis elegans, ELPC-1 and ELPC-3, components of the Elongator complex, are required for the formation of the 5-carbamoylmethyl and 5-methylcarboxymethyl side chains of wobble uridines in tRNA. The lack of these modifications leads to defects in translation in C. elegans. ELPC-1::GFP and ELPC-3::GFP reporters are strongly expressed in a subset of chemosensory neurons required for salt chemotaxis learning. elpc-1 or elpc-3 gene inactivation causes a defect in this process, associated with a posttranscriptional reduction of neuropeptide and a decreased accumulation of acetylcholine in the synaptic cleft. elpc-1 and elpc-3 mutations are synthetic lethal together with those in tuc-1, which is required for thiolation of tRNAs having the 5'methylcarboxymethyl side chain. elpc-1; tuc-1 and elpc-3; tuc-1 double mutants display developmental defects. Our results suggest that, by its effect on tRNA modification, Elongator promotes both neural function and development.

  • 194.
    Chen, Sa
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för molekylärbiologi (Teknisk-naturvetenskaplig fakultet).
    Larsson, Anna L.
    Umeå universitet, Medicinska fakulteten, Institutionen för molekylärbiologi (Medicinska fakulteten).
    Tegeling, Erik
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för molekylärbiologi (Teknisk-naturvetenskaplig fakultet).
    Birve, Anna
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk biovetenskap.
    Rasmuson Lestander, Asa
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för molekylärbiologi (Teknisk-naturvetenskaplig fakultet).
    In vivo analysis of Suppressor of zeste 12´s different isoformsManuskript (Övrigt vetenskapligt)
    Abstract [en]

    Polycomb Group (PcG) genes are known to encode a large chromatin-associated family of proteins which are involved in genomic regulation of many cellular processes. Su(z)12 is a key component in PcG silencing. It is needed for three levels of methylation of histone 3 lysine 27 in vivo in Drosophila. Here, we report that Su(z)12 may exist in different isoforms and that these isoforms are spatially and temporally regulated. The biological function of the Su(z)12-A and -B isoforms seems to be very different. For instance the transgenic Su(z)12-B and the human homolog SUZ12, but not Su(z)12-A, rescue Su(z)12 mutants. Furthermore, transgenic flies over-expressing Su(z)12-B show typical homeotic transformation phenotypes, while over-expression of Su(z)12-A does not. However, the two isoforms appears to be able to substitute for each other in some aspects. During larval and pupal stages, Su(z)12-A seems to play the main role. 

  • 195.
    Chylinski, Krzysztof
    et al.
    Umeå universitet, Medicinska fakulteten, Molekylär Infektionsmedicin, Sverige (MIMS). Umeå universitet, Medicinska fakulteten, Umeå Centre for Microbial Research (UCMR). Umeå universitet, Medicinska fakulteten, Institutionen för molekylärbiologi (Medicinska fakulteten).
    Le Rhun, Anaïs
    Umeå universitet, Medicinska fakulteten, Molekylär Infektionsmedicin, Sverige (MIMS). Umeå universitet, Medicinska fakulteten, Umeå Centre for Microbial Research (UCMR). Umeå universitet, Medicinska fakulteten, Institutionen för molekylärbiologi (Medicinska fakulteten).
    Charpentier, Emmanuelle
    Umeå universitet, Medicinska fakulteten, Molekylär Infektionsmedicin, Sverige (MIMS). Umeå universitet, Medicinska fakulteten, Umeå Centre for Microbial Research (UCMR). Umeå universitet, Medicinska fakulteten, Institutionen för molekylärbiologi (Medicinska fakulteten).
    The tracrRNA and Cas9 families of type II CRISPR-Cas immunity systems2013Ingår i: RNA Biology, ISSN 1547-6286, E-ISSN 1555-8584, Vol. 10, nr 5, s. 726-737Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    CRISPR-Cas is a rapidly evolving RNA-mediated adaptive immune system that protects bacteria and archaea against mobile genetic elements. The system relies on the activity of short mature CRISPR RNAs (crRNAs) that guide Cas protein(s) to silence invading nucleic acids. A set of CRISPR-Cas, type II, requires a trans-activating small RNA, tracrRNA, for maturation of precursor crRNA (pre-crRNA) and interference with invading sequences. Following co-processing of tracrRNA and pre-crRNA by RNase III, dual-tracrRNA:crRNA guides the CRISPR-associated endonuclease Cas9 (Csn1) to cleave site-specifically cognate target DNA. Here, we screened available genomes for type II CRISPR-Cas loci by searching for Cas9 orthologs. We analyzed 75 representative loci, and for 56 of them we predicted novel tracrRNA orthologs. Our analysis demonstrates a high diversity in cas operon architecture and position of the tracrRNA gene within CRISPR-Cas loci. We observed a correlation between locus heterogeneity and Cas9 sequence diversity, resulting in the identification of various type II CRISPR-Cas subgroups. We validated the expression and co-processing of predicted tracrRNAs and pre-crRNAs by RNA sequencing in five bacterial species. This study reveals tracrRNA family as an atypical, small RNA family with no obvious conservation of structure, sequence or localization within type II CRISPR-Cas loci. The tracrRNA family is however characterized by the conserved feature to base-pair to cognate pre-crRNA repeats, an essential function for crRNA maturation and DNA silencing by dual-RNA:Cas9. The large panel of tracrRNA and Cas9 ortholog sequences should constitute a useful database to improve the design of RNA-programmable Cas9 as genome editing tool.

  • 196.
    Chylinski, Krzysztof
    et al.
    Umeå universitet, Medicinska fakulteten, Umeå Centre for Microbial Research (UCMR). Umeå universitet, Medicinska fakulteten, Molekylär Infektionsmedicin, Sverige (MIMS). Umeå universitet, Medicinska fakulteten, Institutionen för molekylärbiologi (Medicinska fakulteten). Max F. Perutz Laboratories, University of Vienna, Austria .
    Makarova, Kira S.
    Charpentier, Emmanuelle
    Umeå universitet, Medicinska fakulteten, Molekylär Infektionsmedicin, Sverige (MIMS). Umeå universitet, Medicinska fakulteten, Umeå Centre for Microbial Research (UCMR). Umeå universitet, Medicinska fakulteten, Institutionen för molekylärbiologi (Medicinska fakulteten). Helmholtz Centre for Infection Research, Department of Regulation in Infection Biology, Braunschweig, Germany ; Hannover Medical School, Hannover, Germany .
    Koonin, Eugene V.
    Classification and evolution of type II CRISPR-Cas systems2014Ingår i: Nucleic Acids Research, ISSN 0305-1048, E-ISSN 1362-4962, Vol. 42, nr 10, s. 6091-6105Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The CRISPR-Cas systems of archaeal and bacterial adaptive immunity are classified into three types that differ by the repertoires of CRISPR-associated (cas) genes, the organization of cas operons and the structure of repeats in the CRISPR arrays. The simplest among the CRISPR-Cas systems is type II in which the endonuclease activities required for the interference with foreign deoxyribonucleic acid (DNA) are concentrated in a single multidomain protein, Cas9, and are guided by a co-processed dual-tracrRNA: crRNA molecule. This compact enzymatic machinery and readily programmable site-specific DNA targeting make type II systems top candidates for a new generation of powerful tools for genomic engineering. Here we report an updated census of CRISPR-Cas systems in bacterial and archaeal genomes. Type II systems are the rarest, missing in archaea, and represented in similar to 5% of bacterial genomes, with an over-representation among pathogens and commensals. Phylogenomic analysis suggests that at least three cas genes, cas1, cas2 and cas4, and the CRISPR repeats of the type II-B system were acquired via recombination with a type I CRISPR-Cas locus. Distant homologs of Cas9 were identified among proteins encoded by diverse transposons, suggesting that type II CRISPR-Cas evolved via recombination of mobile nuclease genes with type I loci.

  • 197.
    Cilio, Corrado M.
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för molekylärbiologi (Medicinska fakulteten). Department of Paediatrics, University of Rome ‘La Sapienza’ Rome, Italy.
    Lejon, Kristina
    Umeå universitet, Medicinska fakulteten, Institutionen för molekylärbiologi (Medicinska fakulteten).
    Penha-Goncalves, Carlos
    Colucci, Francesco
    Bergman, Marie-Louise
    Umeå universitet, Medicinska fakulteten, Institutionen för molekylärbiologi (Medicinska fakulteten).
    Holmberg, Dan
    Umeå universitet, Medicinska fakulteten, Institutionen för molekylärbiologi (Medicinska fakulteten).
    How murine genetics can help to identify susceptibility genes in human disease1998Ingår i: Diabetes Metabolism Reviews, ISSN 0742-4221, E-ISSN 1099-0895, Vol. 14, nr 2, s. 190-191Artikel i tidskrift (Refereegranskat)
  • 198. Codemo, Mario
    et al.
    Muschiol, Sandra
    Iovino, Federico
    Nannapaneni, Priyanka
    Plant, Laura
    Wai, Sun Nyunt
    Umeå universitet, Medicinska fakulteten, Institutionen för molekylärbiologi (Medicinska fakulteten). Umeå universitet, Medicinska fakulteten, Umeå Centre for Microbial Research (UCMR).
    Henriques-Normark, Birgitta
    Immunomodulatory Effects of Pneumococcal Extracellular Vesicles on Cellular and Humoral Host Defenses2018Ingår i: mBio, ISSN 2161-2129, E-ISSN 2150-7511, Vol. 9, nr 2, artikel-id e00559-18Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Gram-positive bacteria, including the major respiratory pathogen Streptococcus pneumoniae, were recently shown to produce extracellular vesicles (EVs) that likely originate from the plasma membrane and are released into the extracellular environment. EVs may function as cargo for many bacterial proteins, however, their involvement in cellular processes and their interactions with the innate immune system are poorly understood. Here, EVs from pneumococci were characterized and their immunomodulatory effects investigated. Pneumococcal EVs were protruding from the bacterial surface and released into the medium as 25 to 250 nm lipid stained vesicles containing a large number of cytosolic, membrane, and surface-associated proteins. The cytosolic pore-forming toxin pneumolysin was significantly enriched in EVs compared to a total bacterial lysate but was not required for EV formation. Pneumococcal EVs were internalized into A549 lung epithelial cells and human monocyte-derived dendritic cells and induced proinflammatory cytokine responses irrespective of pneumolysin content. EVs from encapsulated pneumococci were recognized by serum proteins, resulting in C3b deposition and formation of C5b-9 membrane attack complexes as well as factor H recruitment, depending on the presence of the choline binding protein PspC. Addition of EVs to human serum decreased opsonophagocytic killing of encapsulated pneumococci. Our data suggest that EVs may act in an immunomodulatory manner by allowing delivery of vesicle-associated proteins and other macromolecules into host cells. In addition, EVs expose targets for complement factors in serum, promoting pneumococcal evasion of humoral host defense.

    Importance: Streptococcus pneumoniae is a major contributor to morbidity and mortality worldwide, being the major cause of milder respiratory tract infections such as otitis and sinusitis and of severe infections such as community-acquired pneumonia, with or without septicemia, and meningitis. More knowledge is needed on how pneumococci interact with the host, deliver virulence factors, and activate immune defenses. Here we show that pneumococci form extracellular vesicles that emanate from the plasma membrane and contain virulence properties, including enrichment of pneumolysin. We found that pneumococcal vesicles can be internalized into epithelial and dendritic cells and bind complement proteins, thereby promoting pneumococcal evasion of complement-mediated opsonophagocytosis. They also induce pneumolysin-independent proinflammatory responses. We suggest that these vesicles can function as a mechanism for delivery of pneumococcal proteins and other immunomodulatory components into host cells and help pneumococci to avoid complement deposition and phagocytosis-mediated killing, thereby possibly contributing to the symptoms found in pneumococcal infections.

  • 199. Collin, Betty
    et al.
    Rehnstam-Holm, Ann-Sofi
    Lindmark, Barbro
    Umeå universitet, Medicinska fakulteten, Institutionen för molekylärbiologi (Medicinska fakulteten).
    Pal, Amit
    Wai, Sun N.
    Umeå universitet, Medicinska fakulteten, Institutionen för molekylärbiologi (Medicinska fakulteten).
    Hernroth, Bodil
    the origin of vibrio cholerae influences uptake and persistence in the blue mussel mytilus edulis2012Ingår i: Journal of Shellfish Research, ISSN 0730-8000, E-ISSN 1943-6319, Vol. 31, nr 1, s. 87-92Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Vibrio cholerae may cause diarrheal diseases and wound infections, both of which have the potential to be fatal. Transmission to humans is often linked to consumption of contaminated shellfish/drinking water or dermal exposure to water (e.g. when swimming). In this study, we investigated whether different isolates of Vibrio cholerae differ in terms of accumulation, persistence, and viability when encountering blue mussels (Mytilus edulis). Mussel uptake and elimination of three different V. cholerae strains were compared: one fatal clinical non-OI/O139 isolate, one highly potent El Tor biotype, and one marine strain isolated from blue mussels. The results showed that the uptake of the marine strain was significantly higher than the clinical strain, but the elimination process of the marine strain was also more efficient. The El Tor strain was not at all ingested by the mussels. In addition, the survival of bacteria when incubated together with M. edulis hemocytes was tested in vitro. The viability of clinical strains was unaffected by the presence of hemocytes, and the marine strains were even more resistant and able to multiply. We conclude that the highly virulent El Tor biotype was not taken up by the mussels and could thereby escape the mussels' elimination process. The potentially fatal non-OI/O139 V. cholerae strain may accumulate in low numbers, but could be very persistent in mussels.

  • 200.
    Colucci, Francesco
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för molekylärbiologi (Medicinska fakulteten). INSERM U429, Necker Hospital, Paris, France.
    Bergman, Marie-Louise
    Umeå universitet, Medicinska fakulteten, Institutionen för molekylärbiologi (Medicinska fakulteten).
    Lejon, Kristina
    Umeå universitet, Medicinska fakulteten, Institutionen för molekylärbiologi (Medicinska fakulteten).
    Holmberg, Dan
    Umeå universitet, Medicinska fakulteten, Institutionen för molekylärbiologi (Medicinska fakulteten).
    Diabetes induction in C57BL/6 mice reconstituted with lymphocytes of nonobese diabetic C57BL/6 mouse embryo aggregation chimeras1998Ingår i: Scandinavian Journal of Immunology, ISSN 0300-9475, E-ISSN 1365-3083, Vol. 48, nr 6, s. 571-576Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    To determine whether the genetic background of the insulin-producing beta cells of the pancreas contributes to autoimmune diabetes susceptibility, we have used a model of the disease based on transferring spleen cells from nonobese diabetic (NOD) <--> C57BL/6 (B6) embryo aggregation (EA) chimeras into B6 and NOD irradiated mice. Insulitis and diabetes could be induced into both B6 and NOD hosts, albeit with low incidence. Cyclophosphamide (CY) treatment, known to accelerate diabetes in prediabetic NOD mice, was found to increase diabetes incidence up to 50-60% in both B6 and NOD mice reconstituted with chimeric splenocytes, while diabetes did not occur in CY-treated B6 mice reconstituted with B6 splenocytes. We conclude that the genetic make-up of the target organ does not affect the final stage of the pathogenesis of insulin-dependent diabetes mellitus.

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