Radiosensitization by targeting a novel MAP3K negative regulator STK38

通过靶向新型 MAP3K 负调节因子 STK38 实现放射增敏

基本信息

批准号：
20591491
负责人：
ENOMOTO Atsushi
金额：
$ 3万
依托单位：
The University of Tokyo
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2008
资助国家：
日本
起止时间：
2008 至 2010
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-20591491/
关键词：
増感 STK38 リン酸化酸化ストレス GSK-3 ストレス応答細胞死ストレスシグナル MAP3K

项目摘要

Serine-threonine kinase 38 (STK38) is a member of the protein kinase A (PKA)/PKG/PKC-like family (AGC). However, little is known about its functions or regulatory mechanisms. Among various environmental stresses, STK38 was specifically activated by X-irradiation or H_2O_2, and the phosphatidylinositol 3-kinase inhibitor wortmannin or AKT inhibitor IV suppressed this activation. STK38 was also activated by a constitutively active AKT1 or by GSK-3beta inhibitor VII. Co-immunoprecipitation analysis revealed that GSK-3 physically interacted with STK38 in cells. Overexpression of GSK-3beta inhibited the oxidative stress-stimulated STK38 activity. We identified GSK-3 as an STK38 kinase. GSK-3beta phosphorylated STK38 on residues S6 and T7 in vitro, largely depending on a PKA-mediated priming phosphorylation of STK38 on residues S10 and S11, respectively. STK38's oxidative stress-stimulated activity was enhanced by alanine substitution at its priming sites and/or at S6 and T7, but was partially reduced by a phosphomimetic mutation at S6 or T7. Knockdown or overexpression of the phosphomimetic mutant of STK38 enhanced oxidative stress-induced cell death. Taken together, our results indicate that that GSK-3 inhibits STK38 full activation through phosphorylation, and suggest that the activation of STK38 is required for preventing cell death against oxidative stress.

丝氨酸-苏氨酸激酶 38 (STK38) 是蛋白激酶 A (PKA)/PKG/PKC 样家族 (AGC) 的成员。然而，人们对其功能或调节机制知之甚少。在各种环境胁迫中，STK38被X射线或H_2O_2特异性激活，磷脂酰肌醇3-激酶抑制剂渥曼青霉素或AKT抑制剂IV可抑制这种激活。 STK38 也可以被组成型活性 AKT1 或 GSK-3beta 抑制剂 VII 激活。免疫共沉淀分析显示 GSK-3 与细胞中的 STK38 发生物理相互作用。 GSK-3beta 的过表达抑制了氧化应激刺激的 STK38 活性。我们将 GSK-3 鉴定为 STK38 激酶。 GSK-3beta 在体外磷酸化 STK38 的残基 S6 和 T7，很大程度上取决于 PKA 介导的 STK38 分别在残基 S10 和 S11 上的引发磷酸化。 STK38 的氧化应激刺激活性通过其引发位点和/或 S6 和 T7 处的丙氨酸取代而增强，但通过 S6 或 T7 处的磷模拟突变而部分降低。 STK38 磷酸模拟突变体的敲低或过度表达增强了氧化应激诱导的细胞死亡。综上所述，我们的结果表明 GSK-3 通过磷酸化抑制 STK38 完全激活，并表明 STK38 的激活是防止细胞因氧化应激而死亡所必需的。