Sumoylation of Smad4, the common Smad mediator of transforming growth factor-β family signaling
Sumoylation of Smad4, the common Smad mediator of transforming growth factor-β family signaling
复制标题
DOI：
10.1074/jbc.m301755200
复制
发表时间：
2003-07-25
影响因子：
4.8
通讯作者：
Derynck, R
中科院分区：
文献类型：
--
作者：
Lee, PSW;Chang, CB;Derynck, R
转化生长因子-β (TGF-β) 和 TGF-β 相关因子调节细胞生长、分化和凋亡，在正常发育和肿瘤发生中发挥关键作用。 TGF-β家族诱导的基因表达变化是由细胞表面的丝氨酸/苏氨酸激酶受体和作为细胞内效应器的Smads介导的。受体激活的 Smad 与常见的 Smad4 结合易位到细胞核中，与其他转录因子合作激活或抑制转录。受体激活的 Smad 的活性由磷酸化和泛素化等翻译后修饰控制。在这里我们展示了 Smad4 通过 sumoylation 进行修饰。 Smad4 的 Sumoylation 通过结合酶 Ubc9 和 SUMO 连接酶 PIAS 家族的成员得到增强。 Smad4 中的一个主要苏酰化位点位于其接头片段的 Lys-159 处，另外还有一个位于 MH-1 结构域中的 Lys-113 处的位点。在 PIASy E3 连接酶存在的情况下，SUMO 化的增加与 Smad4 靶向含有 SUMO-1 和 PIASy 的亚核斑点相关。用精氨酸替换赖氨酸 159 和 113 或增加 sumoylation 增强了 Smad4 的稳定性以及哺乳动物细胞和非洲爪蟾胚胎中的转录。这些观察结果表明 Smad4 sumoylation 在通过 Smads 调节 TGF-β 信号传导中发挥作用。
Transforming growth factor-beta (TGF-beta) and TGF-beta-related factors regulate cell growth, differentiation, and apoptosis, and play key roles in normal development and tumorigenesis. TGF-beta family-induced changes in gene expression are mediated by serine/threonine kinase receptors at the cell surface and Smads as intracellular effectors. Receptor-activated Smads combine with a common Smad4 to translocate into the nucleus where they cooperate with other transcription factors to activate or repress transcription. The activities of the receptor-activated Smads are controlled by post-translational modifications such as phosphorylation and ubiquitylation. Here we show that Smad4 is modified by sumoylation. Sumoylation of Smad4 was enhanced by the conjugating enzyme Ubc9 and members of the PIAS family of SUMO ligases. A major sumoylation site in Smad4 was localized to Lys-159 in its linker segment with an additional site at Lys-113 in the MH-1 domain. Increased sumoylation in the presence of the PIASy E3 ligase correlated with targeting of Smad4 to subnuclear speckles that contain SUMO-1 and PIASy. Replacement of lysines 159 and 113 by arginines or increased sumoylation enhanced the stability of Smad4, and transcription in mammalian cells and Xenopus embryos. These observations suggest a role for Smad4 sumoylation in the regulation of TGF-beta signaling through Smads.