成骨细胞增殖调控中雌马酚选择性结合并活化ERβ的机制研究

Postmenopausal osteoporosis (PMOP) is a common disease in postmenopausal women. Because of the adverse reaction of traditional drugs it becomes a new method for prevention and treatment of PMOP by supplement of appropriate phytoestrogens. Studies have shown that soybean isoflavones (SI) can significantly reduce the risk of PMOP, and its final metabolite equol (Eq) has attracted much attention because it presents a much higher biological activity than SI. In previous studies we found that Eq could significantly increase the proliferation of osteoblast (OB), and this effect may be mediated by estrogen receptor beta (ERβ) ,but the mechanism of selectivily binding and activition of ERβ by Eq to promote osteoblast proliperition is still unclear. we propose a hypothesis that Eq promotes the proliferation of osteoblast through selectively binding to estrogen receptor beta, giving rise to a specific conformational change of ER beta and then recruiting corresponding cofactors to activate the ER beta mediated transcription of target genes. We would carry out the structural biology research of the complex of Eq and ER, and detect the transcriptional activity of ER response element (ERE) regulated reporter gene in response to Eq and the variation in expression levels of some downstream genes in ERα or ERβ knockout OB , to clarify the molecular mechanism of selectively binding and stimulation of ER beta pathway by Eq. The research results will further explain the molecular mechanisms of the modulation of osteoblast proliferation by Eq, and provide experimental evidence for new drug design to prevent and treat POMP.

绝经后骨质疏松（PMOP）是绝经后女性的常见疾病，传统药物不良反应明显，补充合适的植物雌激素类化合物成为防治PMOP的新思路。研究表明大豆异黄酮（SI）能够显著降低PMOP的发病风险，而其代谢产物雌马酚（Eq）具有比SI更高的生物活性。我们前期研究发现Eq能够显著促进成骨细胞（OB）增殖，且该作用可能是通过雌激素受体β（ERβ）实现的，但Eq结合并激活ERβ从而调控OB增殖的机制尚不清楚。我们推测Eq是通过选择性结合ERβ，引起ERβ发生特定构象变化，募集相应辅因子，激活ERβ介导的靶基因转录，从而促进OB增殖。为此，本研究通过Eq与ER复合物的结构解析，结合沉默ERα 或 ERβ后的OB中Eq对ER依赖的ERE位点的转录激活作用及下游基因表达变化，阐明Eq选择性结合并活化ERβ途径的分子机制。研究结果将有助于揭示Eq防治PMOP的作用机理，并为开发防治PMOP的临床药物提供新的实验依据。