Oxidized glutathione causes sensitization of calcium release to inositol 1,4,5-trisphosphate in permeabilized hepatocytes.
Oxidized glutathione causes sensitization of calcium release to inositol 1,4,5-trisphosphate in permeabilized hepatocytes.
复制标题
氧化型谷胱甘肽导致透化肝细胞中钙释放对肌醇 1,4,5-三磷酸敏感。
DOI：
10.1042/bj2840507
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发表时间：
1992
期刊：
影响因子：
--
通讯作者：
Thomas,AP
中科院分区：
文献类型：
--
作者：
Renard,DC;Seitz,MB;Thomas,AP
在通透性大鼠肝细胞上研究了GSSG对Ins(1，4，5)P3动员钙离子的影响。GSSG(2 MM)可增加Ins(1，4，5)P3对钙释放的敏感性，但不影响Ins(1，4，5)P3最大浓度时可释放的钙池的大小。GSSG使INS(1，4，5)P3的EC50从对照的578+/-23 nM降至137+/-21 nM。GSSG对INS(1，4，5)P3在通透性细胞中的代谢没有影响，而使用代谢不良的类似物1，4，5-三硫代肌醇仍能敏化细胞内钙离子的释放。GSSG不影响依赖于ATP的钙泵或细胞内钙池的负荷程度。此外，在加入Ins(1，4，5)P3之前用thapsigarin阻断钙泵或通过螯合介质钙离子的情况下，GSSG可增强Ins(1，4，5)P3的敏感性。GSSG的作用呈时间和剂量依赖性，与2 mM GSSG孵育5min后作用最强。半胱氨酸可模拟GSSG引起的INS(1，4，5)P3敏感性增加，这种作用可被二硫苏糖醇(DTT)逆转。DTT、GSH、谷胱甘肽和半胱氨酸单独添加时没有影响。已知的其他与蛋白质硫醇反应的试剂，包括N-乙基马来酰亚胺、对氯汞苯甲酸和Ag+，不影响对Ins(1，4，5)P3的敏感性，但对ATP依赖的钙摄取有抑制作用。这些数据表明，细胞内钙离子池对INS(1，4，5)P3释放的敏感性可以通过与GSSG或其他氧化的硫醇形成混合二硫化物来调节。
The effects of GSSG on Ca2+ mobilization by Ins(1,4,5)P3 were studied in permeabilized rat hepatocytes. Incubation with GSSG (2 mM) increased the sensitivity to Ins(1,4,5)P3 for Ca2+ release, with no effect on the size of the Ca2+ pool that could be released with maximal concentrations of Ins(1,4,5)P3. GSSG decreased the EC50 for Ins(1,4,5)P3 from a control value of 578 +/- 23 nM to 137 +/- 21 nM. GSSG had no effect on the metabolism of Ins(1,4,5)P3 in permeabilized cells, and sensitization of Ca2+ release was still observed when the poorly metabolizable analogue inositol 1,4,5-trisphosphorothioate was used. GSSG did not affect the ATP-dependent Ca2+ pump or the extent of loading of intracellular Ca2+ pools. In addition, the enhancement of Ins(1,4,5)P3-sensitivity by GSSG occurred under conditions where the Ca2+ pumps were blocked with thapsigargin or by chelation of medium Ca2+ just before Ins(1,4,5)P3 addition. The effect of GSSG was time- and dose-dependent, maximal effects being observed after 5 min incubation with 2 mM-GSSG. Cystine mimicked the GSSG-induced increase in Ins(1,4,5)P3-sensitivity, and the effects could be reversed by dithiothreitol (DTT). DTT, GSH glutathione and cysteine had no effect when added alone. Other agents known to react with protein thiols, including N-ethylmaleimide, p-chloromercuribenzoic acid and Ag+, did not affect the sensitivity to Ins(1,4,5)P3, but were inhibitors of ATP-dependent Ca2+ uptake. The data suggest that the sensitivity of the intracellular Ca2+ pools to release by Ins(1,4,5)P3 can be modulated by the formation of mixed disulphides with GSSG or other oxidized thiols.