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- Rodarte, Elsa M, et al.
(författare)
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Munc13 proteins control regulated exocytosis in mast cells.
- 2018
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Ingår i: Journal of Biological Chemistry. - 0021-9258 .- 1083-351X. ; 293:1, s. 345-358
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Tidskriftsartikel (refereegranskat)abstract
- Mast cells (MCs) are involved in host defenses against pathogens and inflammation. Stimulated MCs release substances stored in their granules via regulated exocytosis. In other cell types, Munc13 (mammalian homolog of Caenorhabditis elegans uncoordinated gene 13) proteins play essential roles in regulated exocytosis. Here, we found that MCs express Munc13-2 and -4, and we studied their roles using global and conditional knock-out (KO) mice. In a model of systemic anaphylaxis, we found no difference between WT and Munc13-2 KO mice, but global and MC-specific Munc13-4 KO mice developed less hypothermia. This protection correlated with lower plasma histamine levels and with histological evidence of defective MC degranulation but not with changes in MC development, distribution, numbers, or morphology. In vitro assays revealed that the defective response in Munc13-4-deficient MCs was limited to regulated exocytosis, leaving other MC secretory effector responses intact. Single cell capacitance measurements in MCs from mouse mutants differing in Munc13-4 expression levels in their MCs revealed that as levels of Munc13-4 decrease, the rate of exocytosis declines first, and then the total amount of exocytosis decreases. A requirement for Munc13-2 in MC exocytosis was revealed only in the absence of Munc13-4. Electrophysiology and EM studies uncovered that the number of multigranular compound events (i.e. granule-to-granule homotypic fusion) was severely reduced in the absence of Munc13-4. We conclude that although Munc13-2 plays a minor role, Munc13-4 is essential for regulated exocytosis in MCs, and that this MC effector response is required for a full anaphylactic response.
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- Ilieva, L., et al.
(författare)
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Nanosized gold catalysts on Pr-modified ceria for pure hydrogen production via WGS reaction
- 2015
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Ingår i: Materials Chemistry and Physics. - : Elsevier BV. - 0254-0584 .- 1879-3312. ; 157, s. 138-146
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Tidskriftsartikel (refereegranskat)abstract
- The WGS activity of gold catalysts on ceria doped with Pr (5 and 10 at% Pr) was studied. The supports were synthesized by impregnation (IM) and microemulsion (ME) method. Gold (3 wt%) was introduced by deposition-precipitation method. The samples were characterized by means of XRD, TEM, XPS and TPR measurements. The catalytic activity in WGSR of fresh catalysts did not differ significantly. After re-oxidation following the first catalytic run, the activity of gold catalyst on IM support with 5 at% Pr increased, while a significant drop in activity of the gold catalyst on ME support containing 10 at% Pr was registered. In the latter case the presence of very small gold particles were responsible for the initial WGS activity, while their agglomeration after the catalytic reaction caused the observed activity decrease. In the former case the higher activity during the second catalytic run could be explained by: (i) the redox behavior, showing that only in this case the most mobile oxygen could be fully recovered; (ii) the morphology of the support, revealing better crystallization of the support after WGS catalytic test as compared to the presence of partially amorphous ceria in the fresh gold catalyst.
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