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Calcium signaling and protein kinase C for TNF-alpha secretion in a rat mast cell line.

机译:大鼠肥大细胞系中TNF-α分泌的钙信号和蛋白激酶C。

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In mast cells, like other nonexcitable cells, receptor activation produces Ca2+-mobilizing second messengers such as inositol 1,4,5-triphosphate or sphingosine-1-phosphate, which induce Ca2+ release from internal stores. The resulting depletion of Ca2+ stores activates Ca2+ channels in plasma membranes designated as Ca2+ release-activated Ca2+ (CRAC) channels. Ionomycin appears to cause activation of CRAC channels by depleting intracellular Ca2+ stores rather than by acting as an ionophore. We compared the effects of azelastine, an anti-allergic drug, on TNF-alpha secretion, on Ca2+ signal, and on degranulation in an antigen- or ionomycin-stimulated rat mast RBL-2H3 cell line. Azelastine inhibited TNF-alpha release at concentrations lower than those needed for the inhibition of degranulation. In antigen-stimulated cells, azelastine also inhibited equipotently TNF-alpha mRNA expression/protein synthesis, TNF-alpha release and Ca2+ influx. In ionomycin-stimulated cells, however, azelastine inhibited TNF-alpha release to a greater extent than TNF-alpha mRNA expression/protein synthesis and Ca2+ influx, indicating that azelastine inhibits the release process more potently than transcription or production of TNF-alpha by interfering with a signal other than Ca2+. Pretreatment with 1 microM azelastine inhibited ionomycin-induced, but not antigen-induced, protein kinase C translocation to the membranes. These results suggest that TNF-alpha transcription/production is mainly regulated by Ca2+ influx, but the release process of TNF-alpha is regulated by additional mechanism(s) possibly involving activation of protein kinase C.
机译:在肥大细胞中,像其他非兴奋性细胞一样,受体激活产生Ca2 +动员的第二信使,例如肌醇1,4,5-三磷酸或鞘氨醇-1-磷酸,它们诱导Ca2 +从内部储存区释放。导致的Ca2 +储存耗竭激活了质膜中的Ca2 +通道,称为Ca2 +释放激活的Ca2 +(CRAC)通道。碘霉素似乎通过耗尽细胞内Ca2 +储存而不是通过充当离子载体来引起CRAC通道的激活。我们比较了抗过敏药氮卓斯汀对TNF-α分泌,Ca2 +信号以及抗原或离子霉素刺激的大鼠肥大RBL-2H3细胞系中脱颗粒的影响。氮卓斯汀抑制TNF-α释放的浓度低于抑制脱粒所需的浓度。在抗原刺激的细胞中,氮卓斯汀也同样抑制TNF-αmRNA表达/蛋白质合成,TNF-α释放和Ca2 +涌入。然而,在离子霉素刺激的细胞中,氮卓斯汀比TNF-αmRNA表达/蛋白质合成和Ca 2+涌入抑制TNF-α释放的程度更大,这表明氮卓斯汀通过干扰干扰素比TNF-α的转录或产生更有效地抑制释放过程。 Ca2 +以外的信号。用1 microM氮卓斯汀预处理可以抑制离子霉素诱导的蛋白激酶C向膜的迁移,但不能抑制抗原诱导的蛋白激酶C的移位。这些结果表明,TNF-α的转录/产生主要受Ca2 +流入的调节,但TNF-α的释放过程受可能涉及蛋白激酶C激活的其他机制的调节。

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