Interaction between RAX and PKR modulates the effect of ethanol on protein synthesis and survival of neurons
Interaction between RAX and PKR modulates the effect of ethanol on protein synthesis and survival of neurons
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DOI：
10.1074/jbc.m600612200
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发表时间：
2006-06-09
影响因子：
4.8
通讯作者：
Luo, Jia
中科院分区：
文献类型：
--
作者：
Chen, Gang;Ma, Cuiling;Luo, Jia
乙醇暴露抑制蛋白质合成，并导致中枢神经系统发育中的细胞死亡。双链RNA（dsRNA）激活的蛋白激酶（PKR）是一种丝氨酸/苏氨酸蛋白激酶，在翻译调控和细胞存活中起重要作用。PKR以其抗病毒反应而闻名。在被病毒感染或dsRNA激活后，PKR磷酸化其底物，真核翻译起始因子-2（eIF 2 α）的α亚基，导致翻译起始的抑制。最近已经表明，在没有病毒或dsRNA的情况下，PKR可以通过与其蛋白质激活剂PACT或其小鼠同源物RAX的直接相互作用而被激活。我们已经证明，暴露于乙醇增加了PKR和eIF 2 α在发育中的小脑的磷酸化。乙醇对PKR/eIF 2 α磷酸化的影响与培养神经细胞中PACT/RAX的表达呈正相关。使用PKR抑制剂和PKR无效小鼠成纤维细胞，我们证实了乙醇诱导的eIF 2 α磷酸化是由PKR介导的。野生型RAX的过表达显著增强了对乙醇诱导的PKR/eIF 2 α磷酸化的敏感性，以及翻译抑制和细胞死亡。相反，突变体（S18 A）RAX的过表达抑制乙醇介导的PKR/eIF 2 α活化。乙醇促进PKR和RAX协会在细胞表达野生型RAX，但不是在细胞表达S18 A RAX。S18 A RAX作为显性负性蛋白发挥作用，并阻断乙醇诱导的蛋白质合成抑制和细胞死亡。我们的研究结果表明PKR和PACT/RAX之间的相互作用调节乙醇对中枢神经系统蛋白质合成和细胞存活的影响。
Ethanol exposure inhibits protein synthesis and causes cell death in the developing central nervous system. The double-stranded RNA (dsRNA)-activated protein kinase (PKR), a serine/threonine protein kinase, plays an important role in translational regulation and cell survival. PKR has been well known for its anti-viral response. Upon activation by viral infection or dsRNA, PKR phosphorylates its substrate, the alpha-subunit of eukaryotic translation initiation factor-2 (eIF2 alpha) leading to inhibition of translation initiation. It has recently been shown that, in the absence of a virus or dsRNA, PKR can be activated by direct interactions with its protein activators, PACT, or its mouse homologue, RAX. We have demonstrated that exposure to ethanol increased the phosphorylation of PKR and eIF2 alpha in the developing cerebellum. The effect of ethanol on PKR/eIF2 alpha phosphorylation positively correlated to the expression of PACT/RAX in cultured neuronal cells. Using PKR inhibitors and PKR null mouse fibroblasts, we verified that ethanol-induced eIF2 alpha phosphorylation was mediated by PKR. Overexpression of a wild-type RAX dramatically enhanced sensitivity to ethanol-induced PKR/eIF2 alpha phosphorylation, as well as translational inhibition and cell death. In contrast, overexpression of a mutant (S18A) RAX inhibited ethanol- mediated PKR/eIF2 alpha activation. Ethanol promoted PKR and RAX association in cells expressing wild-type RAX but not in cells expressing S18A RAX. S18A RAX functioned as a dominant negative protein and blocked ethanol-induced inhibition of protein synthesis and cell death. Our results suggest that the interactions between PKR and PACT/RAX modulate the effect of ethanol on protein synthesis and cell survival in the central nervous system.