| 1. |
- Gruic, Mirjana, et al.
(författare)
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Serglycin-deficient cytotoxic T lymphocytes display defective secretory granule maturation and granzyme B storage
- 2005
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Ingår i: Journal of Biological Chemistry. - 0021-9258 .- 1083-351X. ; 280:39, s. 33411-33418
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Tidskriftsartikel (refereegranskat)abstract
- Cytotoxic T lymphocytes eliminate infected and tumor cells mainly by perforin/granzyme-induced apoptosis. Earlier studies suggested that serglycin-proteoglycans form macromolecular complexes with granzymes and perforin in the cytotoxic granule. Serglycin-proteoglycans may also be involved in the delivery of the cytolytic machinery into target cells. We have developed a serglycin-deficient mouse strain, and here we studied the importance of serglycin-proteoglycans for various aspects of cytotoxic T lymphocyte function. 35SO4(2-) radiolabeling of serglycin-deficient cells demonstrated a dramatic reduction of incorporated label as compared with wild type cells, indicating that serglycin is by far the dominating proteoglycan species produced by the cytotoxic T lymphocyte. Moreover, lack of serglycin resulted in impaired ability of cytotoxic T lymphocytes to produce secretory granule of high electron density, although granule of lower electron density were produced both in wild type and serglycin-deficient cells. The serglycin deficiency did not affect the mRNA expression for granzyme A, granzyme B, or perforin. However, the storage of granzyme B, but not granzyme A, Fas ligand, or perforin, was severely defective in serglycin-deficient cells. Serglycin-deficient cells did not display defects in late cytotoxicity toward target cell lines. Taken together, these results point to a key role for serglycin in the storage of granzyme B and for secretory granule maturation but argue against a major role for serglycin in the apoptosis mediated by cytotoxic T lymphocytes.
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| 2. |
- Knight, Stefan David
(författare)
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Structure, Function, and Assembly of Type 1 Fimbriae
- 2009
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Ingår i: Topics in Current Chemistry. - Berlin, Heidelberg : Springer Berlin Heidelberg. - 0340-1022. ; 288, s. 67-107
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Forskningsöversikt (refereegranskat)abstract
- Bacterial infections constitute a major global health problem, acutely accentuated by the rapid spread of antibiotic resistant bacterial strains. The widespread need for bacteria to attach - adhere - to target cells before they can initiate an infection may be used to advantage by targeting the bacterial adhesion tools such as pili and fimbriae for development of novel anti-bacterial vaccines and drugs. Type 1 fimbriae are widely expressed by Escherichia coli and are used by uropathogenic strains to mediate attachment to specific niches in the urinary tract. These fimbriae belong to a class of fibrillar adhesion organelles assembled through the chaperone/usher pathway, one of the terminal branches of the general secretion pathway in Gram-negative bacteria. Our understanding of the assembly, structure and function of these structures has evolved significantly over the last decade. Here, we summarize current understanding of the function and biogenesis of fibrillar adhesion organelles, and provide some examples of recent progress towards interfering with bacterial adhesion as a means to prevent infection.
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| 3. |
- Niemann, Carsten U., et al.
(författare)
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Neutrophil elastase depends on serglycin proteoglycan for localization in granules
- 2007
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Ingår i: Blood. - : American Society of Hematology. - 0006-4971 .- 1528-0020. ; 109:10, s. 4478-4486
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Tidskriftsartikel (refereegranskat)abstract
- Granule proteins play a major role in bacterial killing by neutrophils. Serglycin proteoglycan, the major intracellular proteoglycan of hematopoietic cells, has been proposed to play a role in sorting and packing of granule proteins. We examined the content of major neutrophil granule proteins in serglycin knockout mice and found neutrophil elastase absent from mature neutrophils as shown by activity assay, Western blotting, and immunocytochemistry, whereas neutrophil elastase mRNA was present. The localization of other neutrophil granule proteins did not differ between wild-type and serglycin knockout mice. Differential counts and neutrophil ultrastructure were unaffected by the lack of serglycin, indicating that defective localization of neutrophil elastase does not induce neutropenia itself, albeit mutations in the neutrophil elastase gene can cause severe congenital neutropenia or cyclic neutropenia. The virulence of intraperitoneally injected Gram-negative bacteria (Klebsiella pneumoniae)was increased in serglycin knock-out mice compared with wild-type mice, as previously reported for neutrophil elastase knockout mice. Thus, serglycin proteoglycan has an important role in localizing neutrophil elastase in azurophil granules of neutrophils, while localization of other granule proteins must be mediated by other mechanisms.
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| 4. |
- Pejler, Gunnar, et al.
(författare)
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Novel insights into the biological function of mast cell carboxypeptidase A
- 2009
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Ingår i: Trends in immunology. - : Elsevier BV. - 1471-4906 .- 1471-4981. ; 30:8, s. 401-408
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Forskningsöversikt (refereegranskat)abstract
- When mast cells are activated they can respond by releasing their secretory granule compounds, including mast cell-specific proteases of chymase, tryptase and carboxypeptidase A (MC-CPA) type. MC-CPA is a dominant protein component of the mast cell granule and the MC-CPA gene is extremely highly expressed. Despite this, relatively little has been known of its biological function. However, the recent generation of mouse strains lacking MC-CPA has opened up new possibilities for investigations related to this protease. This recent development has revealed a role for MC-CPA in regulating innate immunity responses, including the degradation of harmful substances such as the vasoconstrictive factor endothelin 1 and snake venom toxins. Here, we summarize the current knowledge of MC-CPA.
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| 5. |
- Zavialov, Anton V, et al.
(författare)
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Resolving the energy paradox of chaperone/usher-mediated fibre assembly
- 2005
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Ingår i: Biochemical Journal. - 0264-6021 .- 1470-8728. ; 389:Pt 3, s. 685-694
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Tidskriftsartikel (refereegranskat)abstract
- Periplasmic chaperone/usher machineries are used for assembly of filamentous adhesion organelles of Gram-negative pathogens in a process that has been suggested to be driven by folding energy. Structures of mutant chaperone–subunit complexes revealed a final folding transition (condensation of the subunit hydrophobic core) on the release of organelle subunit from the chaperone–subunit pre-assembly complex and incorporation into the final fibre structure. However, in view of the large interface between chaperone and subunit in the pre-assembly complex and the reported stability of this complex, it is difficult to understand how final folding could release sufficient energy to drive assembly. In the present paper, we show the X-ray structure for a native chaperone–fibre complex that, together with thermodynamic data, shows that the final folding step is indeed an essential component of the assembly process. We show that completion of the hydrophobic core and incorporation into the fibre results in an exceptionally stable module, whereas the chaperone–subunit pre-assembly complex is greatly destabilized by the high-energy conformation of the bound subunit. This difference in stabilities creates a free energy potential that drives fibre formation.
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