PIASy controls ubiquitination-dependent proteasomal degradation of Ets-1
PIASy controls ubiquitination-dependent proteasomal degradation of Ets-1
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DOI：
10.1042/bj20070026
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发表时间：
2007-08-01
影响因子：
4.1
通讯作者：
Yamada, Yoshiji
中科院分区：
文献类型：
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作者：
Nishida, Tamotsu;Terashima, Motoko;Yamada, Yoshiji
ETS转录因子Ets-1（E26 transformation-specific-1）在包括血管生成、造血发育和肿瘤进展在内的许多生理过程中起关键作用。其活性可通过翻译后修饰如磷酸化来调节。最近，我们发现Ets-1是SUMO（小泛素样修饰剂）修饰的靶点，PIASy [激活STAT（信号转导和转录激活因子）Y的蛋白抑制剂]，Ets-1的特异性SUMO-E3连接酶，抑制Ets-1依赖性转录。在本研究中，我们证明了Ets-1是由蛋白酶体降解的，并且PIASy的过表达通过防止蛋白酶体降解来增加内源性和异位表达的Ets-1蛋白的稳定性。此外，通过RNA干扰敲低内源性PIASy表达降低了内源性Ets-1的蛋白水平。蛋白酶体抑制剂MG 132逆转了这种作用。缺失分析表明，转录激活结构域（transcriptional activation domain，缩写Ets）是Ets-1泛素化和蛋白酶体降解的必需结构域，与PIASy相互作用。然而，PIASy对Ets-1的稳定作用并不是由于Ets-1的泛素化减少。我们的研究结果表明，PIASy控制Ets-1的功能，至少部分，通过抑制Ets-1蛋白周转通过泛素-蛋白酶体系统。
The ETS transcription factor Ets-1 (E26 transformation-specific-1) plays a critical role in many physiological processes including angiogenesis, haematopoietic development and tumour progression. Its activity can be regulated by post-translational modifications, such as phosphorylation. Recently, we showed that Ets-1 is a target for SUMO (small ubiquitin-like modifier) modification and that PIASy [protein inhibitor of activated STAT (signal transducer and activator of transcription) Y], a specific SUMO-E3 ligase for Ets-1, represses Ets-1-dependent transcription. In the present study, we demonstrated that Ets-1 is degraded by the proteasome and that overexpression of PIASy increased the stability of endogenous and ectopically expressed Ets-1 protein by preventing proteasomal degradation. Moreover, knockdown of the endogenous PIASy expression by RNA interference reduced the protein level of endogenous Ets-1. The proteasome inhibitor MG132 reversed this effect. Deletion analysis showed that the TAD (transcriptional activation domain), which has been identified as the interaction domain with PIASy, was also required for Ets-1 ubiquitination and proteasomal degradation. However, the Ets-1 stabilization by PIASy was not due to reduced ubiquitination of Ets-1. Our results suggested that PIASy controls Ets-1 function, at least in part, by inhibiting Ets-1 protein turnover via the ubiquitin-proteasome system.