The Role of Nitric-oxide Synthase in the Regulation of UVB Light-induced Phosphorylation of the α Subunit of Eukaryotic Initiation Factor 2
The Role of Nitric-oxide Synthase in the Regulation of UVB Light-induced Phosphorylation of the α Subunit of Eukaryotic Initiation Factor 2
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DOI：
10.1074/jbc.m109.008821
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发表时间：
2009-09-04
影响因子：
4.8
通讯作者：
Wu, Shiyong
中科院分区：
文献类型：
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作者：
Lu, Wei;Laszlo, Csaba F.;Wu, Shiyong
紫外线诱导真核起始因子 2 (eIF2 α) 的 α 亚基磷酸化并抑制整体蛋白质合成。 eIF2 激酶、蛋白激酶样内质网激酶 (PERK) 和不可抑制蛋白激酶 2 (GCN2) 的一般控制，均已被证明可响应紫外线照射而磷酸化 eIF2 α。然而，PERK 和 GCN2 在紫外线诱导的 eIF2 α 磷酸化中的作用存在争议。导致 PERK 或 GCN2 激活的一种或多种上游信号传导途径仍然未知。在本报告中，我们提供的数据表明，PERK 和 GCN2 均有助于紫外线诱导的人角质形成细胞 (HaCaT) 和小鼠胚胎成纤维细胞中的 eIF2 α 磷酸化。小干扰 RNA 减少 PERK 或 GCN2 的表达会降低 UV 照射后 eIF2 α 的磷酸化。这些数据还表明，一氧化氮合酶 (NOS) 介导的氧化应激在紫外线照射下 eIF2 α 磷酸化的调节中发挥作用。用广泛的 NOS 抑制剂 N-G-甲基-L-精氨酸、自由基清除剂 N-乙酰基-L-半胱氨酸或 NOS 底物 L-精氨酸处理细胞可部分抑制紫外线诱导的 eIF2 α 磷酸化。上述结果使我们提出，NOS 通过氧化应激和 L-精氨酸饥饿信号通路激活 PERK 和 GCN2，介导紫外线诱导的 eIF2 α 磷酸化。
UV light induces phosphorylation of the alpha subunit of the eukaryotic initiation factor 2 (eIF2 alpha) and inhibits global protein synthesis. Both eIF2 kinases, protein kinase-like endoplasmic reticulum kinase (PERK) and general control of nonderepressible protein kinase 2 (GCN2), have been shown to phosphorylate eIF2 alpha in response to UV irradiation. However, the roles of PERK and GCN2 in UV-induced eIF2 alpha phosphorylation are controversial. The one or more upstream signaling pathways that lead to the activation of PERK or GCN2 remain unknown. In this report we provide data showing that both PERK and GCN2 contribute to UV-induced eIF2 alpha phosphorylation in human keratinocyte (HaCaT) and mouse embryonic fibroblast cells. Reduction of expression of PERK or GCN2 by small interfering RNA decreases phosphorylation of eIF2 alpha after UV irradiation. These data also show that nitric-oxide synthase (NOS)-mediated oxidative stress plays a role in regulation of eIF2 alpha phosphorylation upon UV irradiation. Treating the cells with the broad NOS inhibitor N-G-methyl-L-arginine, the free radical scavenger N-acetyl-L-cysteine, or the NOS substrate L-arginine partially inhibits UV-induced eIF2 alpha phosphorylation. The results presented above led us to propose that NOS mediates UV-induced eIF2 alpha phosphorylation by activation of both PERK and GCN2 via oxidative stress and L-arginine starvation signaling pathways.