巴多昔芬/雌激素受体-α促进内皮祖细胞增殖与存活的机制及其对脂毒性心肌病改善作用的研究

Reduction of angiogenesis is one of the important pathophysiological mechanisms of lipotoxic cardiomyopathy, and endothelial progenitor cells (EPC) can promote angiogenesis to delay the progression of this disease possibly. Several studies have shown that estrogen not only can promote EPC proliferation through estrogen receptor-α (ER-α), but also can increase telomerase activity of EPC to delay its survival. However, both the mechanism of up-regulation of telomerase activity and whether EPC can improve lipotoxic cardiomyopathy by promoting angiogenesis remain unclear. Our study will firstly use α-MHC-PPAR-γ mice as a lipotoxic cardiomyopathy model to observe the situation of angiogenesis. Secondly in vitro experiment, we will confirm that bazedoxifene (BXF) which is an estrogen receptor modulator can enhance telomerase activity and promote EPC proliferation and survival through ER-α in two aspects: transcriptional regulation [promoting telomerase reverse transcriptase (TERT) transcription] and post-translational regulation (promoting TERT phosphorylation). Finally, EPC which overexpress ER-α gene will be transfused back to lipotoxic cardiomyopathy model, with or without BXF intervention, to be proven that BXF / ER-α-EPC can improve lipotoxic cardiomyopathy by promoting angiogenesis. This study aimed to clarify the roles of BXF / ER-α and EPC in lipotoxic cardiomyopathy, in order to provide a new idea for the prevention of this disease.

血管生成减少是脂毒性心肌病的重要病理生理机制之一，而内皮祖细胞(EPC)促进血管生成的作用可能会延缓疾病进展。研究表明，雌激素可通过雌激素受体-α(ER-α)促进EPC增殖，同时能上调EPC端粒酶活性来延长其存活时间，但活性上调的具体机制及EPC是否通过血管生成来改善脂毒性心肌病均不明确。本研究将首先利用α-MHC-PPAR-γ小鼠构建脂毒性心肌病模型，观察血管生成情况。其次经体外研究证实雌激素受体调节剂巴多昔芬(BXF)通过ER-α在转录调节[促进端粒酶逆转录酶(TERT)转录]和翻译后调节(促进TERT磷酸化)这两个方面来增强端粒酶活性并促进EPC增殖及存活。最后，通过回输过表达ER-α的EPC至脂毒性心肌病小鼠模型，并予BXF干预，证实BXF/ER-α-EPC通过促进血管生成来改善脂毒性心肌病。本研究旨在阐明BXF/ER-α及EPC对脂毒性心肌病的作用，为该病的防治提供新的思路。

血管生成减少是心梗后心室重塑的重要病理生理机制之一，而内皮祖细胞(EPC)促进血管生成的作用可能会延缓疾病进展。研究表明，雌激素受体调节剂巴多昔芬(BXF)可通过雌激素受体-α(ER-α)促进EPC增殖，同时能上调EPC端粒酶活性来延长其存活时间，但活性上调的具体机制及EPC是否通过血管生成来改善心梗后心室重塑均不明确。本研究首先成功构建表达ER-α的EPC细胞，加入BXF刺激后的ER-α-EPC增殖能力和成血管能力增强、端粒酶活性升高。而BXF刺激后再予sh-RNA干扰的ER-α-EPC，其增殖能力和成血管能力均减弱，端粒酶活性亦降低。未经BXF处理的ER-α-EPC的端粒酶活性较BXF刺激的下降，其增殖能力和成血管能力减弱。其次阐明了BXF/ ER-α增强EPC端粒酶活性机制是通过TERT磷酸化途径实现的。最后通过在高脂饮食合并心梗的小鼠模型体内回输ER-α-EPC或不表达ER-α的eGFP-EPC并予BXF干预，结果发现BXF可改善回输ER-α-EPC组的心功能，但不改善回输eGFP-EPC的心功能。综上所述，BXF通过ER-α促进EPC增殖和上调EPC端粒酶活性促进血管生成来改善心梗后心室重塑，其机制是通过TERT磷酸化途径实现的。这为治疗心梗后心室重塑提供了一个新的思路。