sigma-1 receptors protect RGC-5 cells from apoptosis by regulating intracellular calcium, Bax levels, and caspase-3 activation.
sigma-1 receptors protect RGC-5 cells from apoptosis by regulating intracellular calcium, Bax levels, and caspase-3 activation.
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DOI：
10.1167/iovs.07-1101
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发表时间：
2008-06
影响因子：
4.4
通讯作者：
K. Tchedre;T. Yorio
中科院分区：
文献类型：
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作者：
K. Tchedre;T. Yorio
目的：Sigma-1受体配体在体外和体内均可预防谷氨酸兴奋性毒性引起的神经元死亡。然而，其神经保护作用的分子机制仍有待阐明。本研究旨在确定Sigma-1受体激动剂是否通过减少谷氨酸诱导的钙动员和阻止凋亡基因的表达来提供神经保护。方法采用钙调素-AM/碘化丙啶细胞存活实验检测细胞死亡。Western印迹分析检测Bax在正常RGC-5细胞中的表达水平。用羧基荧光素caspase-3检测试剂盒检测谷氨酸处理后caspase-3的活性。用比值钙显像法测定谷氨酸诱导的细胞内钙动员。结果高表达Sigma-1受体的RGC-5(RGC-5-S1R)细胞对谷氨酸诱导的细胞内钙动员低于正常RGC-5细胞，Sigma-1受体配体(+)-SKF10047降低了正常和RGC-5-S1R细胞的谷氨酸钙反应。(+)-SKF10047保护RGC-5细胞免受谷氨酸诱导的细胞死亡，与对照组RGC-5细胞相比，RGC-5-S1R细胞对谷氨酸诱导的细胞凋亡表现出明显的抵抗作用。Sigma-1受体拮抗剂BD1047可阻断(+)-SKF10047的保护作用。Western印迹分析表明，(+)-SKF10047抑制谷氨酸处理后Bax的增加。谷氨酸介导的细胞死亡涉及caspase-3的激活，而Sigma-1受体的激活阻止了caspase-3表达的增加。结论Sigma-1受体可调节视网膜神经节细胞内钙离子水平，阻止促凋亡基因的激活，从而促进视网膜神经节细胞存活。Sigma-1配体似乎具有神经保护作用，是神经保护疗法的潜在靶点。
PURPOSE sigma-1 Receptor ligands prevent neuronal death associated with glutamate excitotoxicity both in vitro and in vivo. However, the molecular mechanism of the neuroprotective effect remains to be elucidated. The present study was undertaken to determine whether sigma-1 receptor agonists provide neuroprotection by decreasing glutamate-induced calcium mobilization and preventing apoptotic gene expression. METHODS Cell death was measured by using a calcein-AM/propidium iodide cell-survival assay. Western blot analysis determined the expression levels of Bax in normal RGC-5 cells. Caspase-3 activation after glutamate treatment was determined with a carboxyfluorescein caspase-3 detection kit. Glutamate-induced intracellular calcium mobilization was measured by using ratiometric calcium imaging. RESULTS sigma-1 Receptor-overexpressing RGC-5 (RGC-5-S1R) cells had lower glutamate-induced intracellular calcium mobilization than did normal RGC-5 cells, and the sigma-1 receptor ligand (+)-SKF10047 reduced the glutamate calcium response in normal and RGC-5-S1R cells. (+)-SKF10047 protected RGC-5 cells from glutamate-induced cell death, and the RGC-5-S1R cells showed a significant resistance to glutamate-induced apoptosis compared with the control RGC-5 cells. BD1047, a sigma-1 receptor antagonist, blocked the protective effect of (+)-SKF10047. Western blot analysis showed that (+)-SKF10047 inhibited the increase in Bax after glutamate treatments. Glutamate-mediated cell death involved activation of caspase-3, and sigma-1 receptor activation prevented an increase in caspase-3 expression. CONCLUSIONS The results suggest that sigma-1 receptors regulate intracellular calcium levels and prevent activation of proapoptotic genes, thus promoting retinal ganglion cell survival. The sigma-1 ligands appear to be neuroprotective and are a potential target for neuroprotective therapeutics.