Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0393754 (HSA)
 2,996 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Fas is an apoptosis-related cell surface molecule whose defective transcription results in the lpr defect and autoimmunity. Recent analysis of Fas mRNA and protein expression in normal mice showed high expression in the thymus, on activated T cells, and on 5-10% of peripheral T cells. To investigate the role of Fas in the thymus, we analyzed its expression in fetal and adult thymocyte subsets. Fas was not expressed on fetal nor adult CD8-CD4- (double-negative, DN) T cell precursors. The earliest precursors that expressed low levels of FAS were the immediate precursors of DP thymocytes that bear the CD44-CD25-CD8loCD4loTCRlo phenotype. Other DN cells that expressed Fas appeared to be either non-T cells or mature alpha beta + DN thymocytes. The onset of Fas expression followed the onset of expression of CD8 and CD4 and Fas expression reached its peak in CD8+CD4+ double-positive (DP) thymocytes. Both single-positive (SP) subsets were largely Fas+ (CD8 SP < CD4 SP) but expressed lower levels of Fas than DP cells. However, a majority (> 60%) of the most mature HSA(lo) SP cells (2-5% of all SP thymocytes) were Fas- and the remainder of the HSA(lo) SP cells was Fas(lo). We observed two main differences between Fas expression on fetal versus adult thymocytes. First, up to 90% of fetal gamma delta + DN cells expressed high levels of Fas, in contrast to the very low expression (< 7% Fas+ cells) among adult gamma delta + thymocytes. Second, whereas virtually all adult DP cells were Fas+, up to 75% of fetal day 16 DP cells were Fas-.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:The onset of Fas expression parallels the acquisition of CD8 and CD4 in fetal and adult alpha beta thymocytes. 751 29

B lymphocyte generation in bone marrow (BM) compensates for cell loses. The Fas / Fas ligand (FasL) pathway has been implicated in apoptosis of various cell types. Abnormalities of the Fas receptor or of FasL expression are associated with excessive T cell proliferation and autoimmunity. To examine the role of the Fas / FasL system in B cell differentiation, we created double-chimeric mice by transferring both C57BL / 6 (B6)-Fas(+) and lpr-FasL(+) BM cells into RAG-2(- / -) hosts. Equal numbers of stem cells were co-injected into sublethally irradiated recipients, and their progeny were studied by using antibodies directed against the B6-Ly5. 1(+)5.2(+) and lpr-Ly5.1(-)5.2(+) populations. A longitudinal study lasting for up to 6 months revealed that cells of the lpr phenotype dominated the B6 phenotype in the BM, as a result of their active proliferation. Analysis of the B cell compartment showed more lpr than B6 cells among immature HSA(hi)B220(lo) populations. In contrast, the lpr and B6 phenotypes were equally represented among mature B cells. BM transfer to second hosts indicated that B6-derived B cell progenitors were absent from the first host. These data suggest that activation of the Fas / FasL pathway disturbs the early steps of B cell development and might therefore contribute to the onset of autoimmune disorders.
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PMID:Selective involvement of the Fas (CD95)/Fas ligand pathway in bone marrow B cell progenitors. 1082 Mar 87

Self-tolerance induction is largely a reflection of negative selection (deletion) of autoreactive T cells in the thymus. Evidence is presented that negative selection occurs at a relatively late stage of thymocyte differentiation and affects a population of semimature HSA(hi) CD4+8- cells found in the medulla. Negative selection involves a number of cell-surface molecules on T cells, including Fas, CD28, CD5, and CD43. These molecules appear to act in consort, thereby ensuring that negative selection is highly efficient.
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PMID:The thymus and negative selection. 1085 32

Binding of oleate to S-nitrosylated human serum albumin (SNO-HSA) enhances its cytoprotective effect on liver cells in a rat ischemia/reperfusion model. It enhances the antiapoptotic effect of SNO-HSA on HepG2 cells exposed to anti-Fas antibody. To identify some of the reasons for the increased cytoprotective effects, additional experiments were performed with glutathione and HepG2 cells. As indicated by 5,5'-dithiobis-2-nitrobenzoic acid binding, the addition of oleate increased the accessibility of the single thiol group of albumin. Binding of increasing amounts of oleate resulted in increasing and more rapid S-transnitrosation of glutathione. Likewise, binding of oleate, or of a mixture of endogenous fatty acids, improved S-denitrosation of SNO-HSA by HepG2 cells. Oleate also enhanced S-transnitrosation by HepG2 cells, as detected by intracellular fluorescence of diaminofluorescein-FM. All of the S-transnitrosation caused by oleate binding was blocked by filipin III. Oleate also increased, in a dose-dependent manner, the binding of SNO-HSA labeled with fluorescein isothiocyanate to the surface of the hepatocytes. A model in two parts was worked out for S-transnitrosation, which does not involve low molecular weight thiols. Fatty acid binding facilitates S-denitrosation of SNO-HSA, increases its binding to HepG2 cells and greatly increases S-transnitrosation by hepatocytes in a way that is sensitive to filipin III. A small nitric oxide transfer takes place in a slow system, which is unaffected by fatty acid binding to SNO-HSA and not influenced by filipin III. Thus, fatty acids could be a novel type of mediator for S-transnitrosation.
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PMID:S-nitrosylated human serum albumin-mediated cytoprotective activity is enhanced by fatty acid binding. 1894 Aug 10