Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P15088 (mast cell)
 14,925 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Cross-linking of 125I-IL-4 to the surface of cells expressing IL-4R yields as the major IL-4-binding molecules, polypeptide chains with inferred m.w. of approximately 70,000 (p70) and approximately 120,000 to 140,000 (p120-p140). The demonstration that the functional product of the IL-4R cDNA clone has m.w. of approximately 140,000 and that no p70 product is detected in transfected COS-7 cells has led to an uncertainty regarding the nature of p70. To study this issue, we examined the relationship of the IL-4-binding molecules p120 and p70 and, in parallel, attempted to immunoprecipitate p70 from surface and internally labeled cells using IL-4 and two anti-IL-4R antibodies (M1 and M2), bound to Affigel 10, as ligands. Cross-linked complexes containing 125I-IL-4 and p70 or p120 were isolated and digested with chymotrypsin or with V8 protease. Three distinct IL-4-binding peptides could be compared; these were indistinguishable for cross-linked p70 and p120, strongly implying that p70 and p120 were structurally related. Furthermore, immunoprecipitates made with IL-4 or anti-IL-4R-Affigel did not contain p70. This led us to conclude that p70 is a breakdown product of p120. A second IL-4-binding molecule of 40,000 Da (p40) expressing the M1 and M2 epitopes of the IL-4R was detected and appears to be the product of an mRNA coding for the soluble form of the receptor. mRNA for p40 was detected in both the T cell line CT.4R and the mast cell line CFTL.12 using polymerase chain reaction primers unique to this species of message. Pulse-chase studies of IL-4R in [35S] methionine-labeled cells indicates that p40 is derived from a 42,000-Da precursor that is detectable at the end of the pulse period, and thus, further argue that p40 is an independently translated molecule and not a degradation product of p120. Although p40 has been previously shown to be a soluble, truncated form of the receptor, we failed to observe secretion of p40 into the medium by internally labeled CT.4R cells.
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PMID:The IL-4 receptor: biochemical characterization of IL-4-binding molecules in a T cell line expressing large numbers of receptors. 200 96

Signal transducer and activator of transcription (Stat)-6 is the principle Stat protein activated by interleukin (IL)-4. We defined a role for IL-4 in mast cell homeostasis through inhibiting expression of Kit and F(c)epsilonRI, and by inducing mast cell apoptosis. These effects required Stat6 expression. A molecular mechanism by which Stat6 directs these inhibitory actions in BMMC was potentially elucidated by the discovery of a carboxyl-truncated Stat6 isoform. Expression of this 70kDa isoform was unique to cultured mast cells and mast cell lines. Furthermore, this isoform lacked a carboxyl-transactivation domain, suggesting that it might behave as a dominant negative isoform. To better understand this truncated Stat6, we characterized its origins. Using Western blotting and electrophoretic mobility shift assay analysis, we assessed BMMC p70 Stat6 expression using standard and enhanced protease inhibitor cocktails. These experiments demonstrated that p70 Stat6 is derived by proteolysis during sample preparation, and has no cellular correlate. While some Stat family members are known to exist as naturally occurring truncated forms, p70 Stat6 does not appear to be such a case. Instead, the very high concentrations of proteases released during mast cell lysis result in selective proteolysis of the full-length Stat6, with p70 being the major degradation product.
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PMID:Mast cell-restricted p70 Stat6 isoform is a product of selective proteolysis. 1239 68

The secretagogue compound 48/80 (c48/80) is a well known activator of calcium mediated processes and PKCs, and is a potent inducer of mast cell degranulation. As the latter process is a phosphoinositide 3-kinase (PI 3-kinase) mediated event, we wished to address whether or not c48/80 was an activator of PI 3-kinases. The data presented here reveal that c48/80 is an effective activator of PI 3-kinases as judged by the increased phosphorylation of PKB and p70(S6K) in fibroblasts in a PI 3-kinase dependent fashion. Compound 48/80 effectively translocates PKB to the plasma membrane and induces phosphorylation at serine 473 (S473), detected by fluorescence imaging of fixed cells. At higher concentrations the secretagogue is inhibitory towards PKB phosphorylation on S473. Conversely, p70(S6K) phosphorylation on T389 is unaffected at high doses. We provide evidence that the differential effect on the two PI 3-kinase effectors is due to activation of PKCalpha by c48/80, itself a PI 3-kinase dependent process. We conclude that compound 48/80 is an effective activator of PI 3-kinase dependent pathways, leading to the activation of effectors including PKB/Akt, p70(S6K) and PKCalpha. The latter is only activated by higher doses of c48/80 resulting in an inhibition of the c48/80 induced PKB phosphorylation, thus explaining the observed biphasic activation profile for PKB in response to this secretagogue.
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PMID:Differential activation of the PI 3-kinase effectors AKT/PKB and p70 S6 kinase by compound 48/80 is mediated by PKCalpha. 1694 62