膜雌激素受体α、β亚型调节血小板淀粉样前体蛋白代谢的信号转导机制

Research findings suggest that the overproduction of blood Aβ promotes atherogenesis. However, it remains unclear how the increase of blood Aβ occurs. Aβ is one of the cleavage products of APP，and blood Aβ is mainly derived from platelet APP. Our previous studies have demonstrated that ER-mediated cellular signaling is involved in APP metabolism. Our preliminary data further suggest that activation of membrane ERα and ERβ promotes α secretase- and β secretase-mediated APP metabolism, respectively. Therefore, we propose a new mechanism of AS in this project, i.e., membrane ERα and ERβ promotes α secretase- and β secretase-mediated APP metabolism, respectively, which keeps Aβ levels steady; disturbance of ER-mediated platelet APP metabolism may lead to the increase of blood Aβ and even atherogenesis. Using platelets, this proposed project will test whether and how membrane ERα and ERβ modulates APP processing and whether membrane ER-mediated APP metabolism is involved in atherogenesis. This will be done using the inhibitors of some kinases, the agonists and antagonists of ER, ER transgenic mice, western blot and immunoprecipitation etc. The results will provide new insights into atherogenesis and will aid in developing new therapeutic strategies for AS.

研究发现，血液中β淀粉样多肽（Aβ）的过度生成可促进动脉粥样硬化（AS）形成，但血液中Aβ生成的调控机制不明。Aβ是淀粉样前体蛋白（APP）的代谢产物之一，而血液中Aβ主要源于血小板APP。前期研究发现，雌激素受体（ER）介导的细胞信号可调节APP代谢。预实验进一步显示：膜ERα和ERβ的激活分别促进α-和β-分泌酶介导的APP代谢。由此，我们提出AS发生机制的新假设：膜ERα和ERβ介导的细胞信号分别促进α-和β-分泌酶介导的APP代谢，使Aβ水平相对稳定；如ER介导的血小板APP代谢平衡被打破，则可导致血液中Aβ增多，促进AS发生。本项目拟对膜ERα和ERβ调节血小板APP代谢的效应及信号机制进行研究；并检测这一机制在AS形成中的作用。主要实验手段包括使用一些激酶的抑制剂，ER的激活剂及拮抗剂，ER转基因鼠，Western blot，免疫沉淀等。研究结果将为AS的发生和防治打开新视角。

研究发现，血液中β淀粉样多肽（Aβ）的过度生成可促进动脉粥样硬化（AS）形成。雌激素受体（ER）介导的细胞信号可调淀粉样前体蛋白（APP）代谢。本研究采用Western blot、免疫沉淀、流式细胞技术、ELISA等手段，ER转基因小鼠和淀粉样前体蛋白/早老素双转基因动物模型（APP/PS1小鼠）对血液中Aβ生成的调控机制进行进行了研究，首次发现：（1）ERα可通过与Shc的结合激活MAPK/ERK通路，并通过MAPK/ERK信号促进血小板ADAM17苏氨酸残基的磷酸化，从而促使血小板APP经α内分泌酶途径进行代谢。（2）血小板Aβ的过度生成可诱发血管内皮细胞的凋亡。激活ERα可防止因血小板Aβ过度生成导致的血管内皮细胞损伤。（3）激活ERβ对血小板APP代谢无明显调节作用，但对ERβ进行基因敲除可通过JNK通路促进血小板APP经β内分泌酶途径进行代谢。上述结果证实ER介导的细胞信号可调节血小板APP代谢。研究结果将为AS的发生和防治打开新视角。