PIAS1 mediates TGFbeta-induced SM alpha-actin gene expression through inhibition of KLF4 function-expression by protein sumoylation.
PIAS1 mediates TGFbeta-induced SM alpha-actin gene expression through inhibition of KLF4 function-expression by protein sumoylation.
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DOI：
10.1161/atvbaha.108.172700
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发表时间：
2009-01
期刊：
影响因子：
--
通讯作者：
Kurabayashi M
中科院分区：
文献类型：
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作者：
Kawai-Kowase K;Ohshima T;Matsui H;Tanaka T;Shimizu T;Iso T;Arai M;Owens GK;Kurabayashi M
TGFβ 和平滑肌细胞 (SMC) 的增殖/表型转换在血管成形术后动脉粥样硬化和再狭窄病变的发病机制中发挥着关键作用。我们之前已经证明，激活的 STAT (PIAS)1 的蛋白抑制剂通过与血清反应因子 (SRF) 和 I 类 bHLH 蛋白相互作用，激活 SMC 分化标记基因的表达，包括平滑肌 (SM) α-肌动蛋白。在这里，我们测试了 TGFβ 通过 PIAS1 激活 SM α-肌动蛋白的假设。通过实时 RT-PCR 测定，PIAS1 和 ubc9 特异的 siRNA（一种用于 sumoylation 的 E2 连接酶）抑制培养 SMC 中 TGFβ 诱导的 SM α-肌动蛋白表达。 PIAS1 的过表达以 TGFβ 控制元件 (TCE) 依赖性方式增加 SM α-肌动蛋白启动子活性。由于 SM α-肌动蛋白启动子内的 TCE 可以通过与 KLF4 相互作用介导抑制，因此我们测试了 PIAS1 是否调节 KLF4 对 SMC 基因表达的功能。在哺乳动物双杂交和免疫共沉淀测定中，PIAS1 与 KLF4 相互作用，并且 PIAS1 的过表达抑制 KLF4 对 SM α-肌动蛋白启动子活性的抑制。此外，PIAS1 通过苏酰化促进 KLF4 的降解。这些结果证明PIAS1至少部分通过促进TCE阻遏蛋白KLF4的SUMO化和降解来促进TGFβ诱导的SM α-肌动蛋白基因表达的激活。
TGFβ and proliferation/phenotypic switching of smooth muscle cells (SMCs) play a pivotal role in pathogenesis of atherosclerotic and restenotic lesions after angioplasty. We have previously shown that the protein inhibitor of activated STAT (PIAS)1 activates expression of SMC differentiation marker genes including smooth muscle (SM) α-actin by interacting with serum response factor (SRF) and class I bHLH proteins. Here, we tested the hypothesis that TGFβ activates SM α-actin through PIAS1. An siRNA specific for PIAS1 and ubc9, an E2-ligase for sumoylation, inhibited TGFβ-induced expression of SM α-actin in cultured SMCs as determined by real-time RT-PCR. Overexpression of PIAS1 increased SM α-actin promoter activity in a TGFβ control element (TCE)-dependent manner. Because the TCE within the SM α-actin promoter could mediate repression through interaction with KLF4, we tested whether PIAS1 regulates the function of KLF4 for SMC gene expression. PIAS1 interacted with KLF4 in mammalian two-hybrid and coimmuno-precipitation assays, and overexpression of PIAS1 inhibited KLF4-repression of SM α-actin promoter activity. Moreover, PIAS1 promoted degradation of KLF4 through sumoylation. These results provide evidence that PIAS1 promotes TGFβ-induced activation of SM α-actin gene expression at least in part by promoting sumoylation and degradation of the TCE repressor protein, KLF4.