INVESTIGATION OF MECHANISM OF PREVENTION OF ATHEROSCLEROSIS BY SELECTIVE ESTROGEN RECEPTOR MODULATORS (SERM)

1)利用酵母双杂交系统从人心脏cDNA文库中筛选雌激素受体α (Estrogen Receptor α, ERα)相互作用蛋白。我们成功地鉴定了含有lim -only结构域的因子FHL2和summoylation酶Ubc9和PIAS1是雌二醇敏感的er α-相互作用蛋白。FHL2在心肌中特异性高表达，并报道其与雄激素受体、AP-1、CREB和CREM等转录因子相互作用。这是首次报道FHL2作为ERα相互作用蛋白。在17β-雌二醇存在的情况下，FHL2与ERα相互作用，但利用ERE-E 1b荧光素酶报告基因进行瞬时转染实验，发现ERα对FHL2的转录活性没有显著影响。鉴于FHL2在心肌中特异性高表达，FHL2可能参与心脏肥厚的病理生理过程。2)我们之前已经发现SUMOylation酶Ubc9和PIAS1是COUP-TFI相互作用的蛋白。在本项目中，我们也将它们鉴定为er α-相互作用蛋白。我们研究了这些蛋白在er介导的转录中的作用，发现它们是ERα的转录辅激活因子。最近有报道表明，COUP-TFI通过磷酸化ERα的Ser118激活ERα，因此可以想象Ubc9、PIAS1和COUP-TFI形成三元配合物来调节ERα的转录活性。

1) We screened Estrogen Receptor α (ERα)-interacting proteins using yeast two hybrid system from a human heart cDNA library. We successfully identified LIM-only-domain containing factor FHL2 and Sumoylation enzymes Ubc9 and PIAS1 as ERα-interacting proteins in an estradiol-sensitive manner. FHL2 is highly expressed in cardiac muscle specifically, and reported that it interacts with several transcription factors, such as Androgen Receptor, AP-1, CREB and CREM. This is the first report of FHL2 as ERα interacting protein. FHL2 interacts with ERα in the presence of 17β-estradiol, but there was no significant influence on transcriptional activity through ERα by transient transfection assay using an ERE-E 1b-Luciferase reporter. Given the fact that FHL2 is specifically highly expressed in the cardiac muscle, FHL2 is likely to be involved in the pathophysiology of cardiac hypertrophy.2) We have previously identified SUMOylation enzymes Ubc9 and PIAS1 as COUP-TFI interacting proteins. In the present project, we also identified them as ERα-interacting proteins. We investigated the role of these proteins in ER-mediated transcription, and found that they function as transcriptional coactivators of ERα. Since a recent report showed that COUP-TFI activates ERα through phospholylation of Ser118 of ERα, it is conceivable that Ubc9, PIAS1 and COUP-TFI form ternary complex to modulate ERα transcriptional activities.