Department of Molecular Biosciences, University of Kansas, 1200 Sunnyside Ave., Haworth Hall, Rm. 3037, Lawrence, KS 66045, USA.
J Cell Sci. 2012 Dec 1;125(Pt 23):5819-29. doi: 10.1242/jcs.110825. Epub 2012 Sep 12.
The small ubiquitin-like modifier (SUMO) ligase PIAS1 (Protein Inhibitor of Activated Stat-1) has been shown to play a role in cellular stress response by SUMOylating several proteins that are involved in DNA repair, apoptosis and transcription. In this paper, we show that PIAS1 regulates ultraviolet (UV)-induced apoptosis by recruiting Death-associated protein 6 (Daxx) to PIAS1-generated SUMO-foci. Cells that ectopically express PIAS1, but not other PIASes, show increased sensitivity to UV irradiation, suggesting that PIAS1 has a distinct function in UV-dependent apoptosis. Domain analysis of PIAS1 indicates that both PIAS1 SUMO-ligase activity and the specific localization of PIAS1 through its N-terminal and C-terminal domains are essential for UV-induced cell death. Daxx colocalizes with PIAS1-generated SUMOylated foci, and the reduction of Daxx using RNAi alleviates UV-induced apoptosis in PIAS1-expressing cells. PIAS1-mediated recruitment of Daxx and apoptosis following UV irradiation are dependent upon the Daxx C-terminal SUMO-interacting motif (SIM). Overall, our data suggest that the pro-apoptotic protein Daxx specifically interacts with one or more substrates SUMOylated by PIAS1 and this interaction leads to apoptosis following UV irradiation.
小泛素样修饰物（SUMO）连接酶 PIAS1（激活的 Stat-1 蛋白抑制剂）已被证明通过 SUMO 化参与 DNA 修复、细胞凋亡和转录的几种蛋白质在细胞应激反应中发挥作用。在本文中，我们表明 PIAS1 通过将 Death-associated protein 6（Daxx）募集到 PIAS1 产生的 SUMO 焦点来调节紫外线（UV）诱导的细胞凋亡。异位表达 PIAS1 的细胞而不是其他 PIASes 的细胞对 UV 照射表现出更高的敏感性，这表明 PIAS1 在 UV 依赖性细胞凋亡中具有独特的功能。PIAS1 的结构域分析表明，PIAS1 的 SUMO 连接酶活性和通过其 N 端和 C 端结构域的 PIAS1 的特异性定位对于 UV 诱导的细胞死亡都是必需的。Daxx 与 PIAS1 产生的 SUMO 化焦点共定位，并且使用 RNAi 减少 Daxx 可减轻 PIAS1 表达细胞中的 UV 诱导的细胞凋亡。PIAS1 介导的 Daxx 募集和 UV 照射后的细胞凋亡依赖于 Daxx C 末端 SUMO 相互作用基序（SIM）。总的来说，我们的数据表明促凋亡蛋白 Daxx 与 PIAS1 SUMO 化的一个或多个底物特异性相互作用，这种相互作用导致 UV 照射后的细胞凋亡。
