Bestrophin 3 参与高血压血管重构及机制研究

Our recent study excluded the possibility that bestrophin 3 is the molecular candidate of calcium activated chloride channel,however, its functions in cardiovascular system remain elusive. Our primary data showed that bestrophin 3 expression was increased during hypertension-induced vascular remodeling. Knockdown of bestrophin 3 inhibited cell proliferation but promoted cell apoptosis, in vascular smooth mucle cells. Bestrophin 3 can bind to the PI3K p110 subunit and knockdown of bestrophin 3 reduced the activity of PI3K-Akt pathway. Our present study aimed to further clarify the interaction of bestrophin 3 and PI3K p110 and how this interaction interferes with the activity of PI3K-Akt signaling pathway and thus regulates cell proliferation and apoptosis. Moreover, we will investigate the functional role of bestrophin 3 in regulating hypertension-induced coronary atery remodeling in bestrophin 3 knockout mice. This work will reveal the new functions of bestrophin-3 and raise the possibility that bestrophin 3 is a key regulator of PI3K-Akt pathway,suggesting that bestrophin 3 may be a novel therapeutic target for hypertension-induced vascular remodeling.

我们最近的研究否定了bestrophin 3是钙激活氯通道分子基础的传统观点，但其在心血管系统中的功能不清楚。预实验结果发现，bestrophin 3表达在高血压血管重构过程中显著升高。下调bestrophin 3可抑制血管平滑肌细胞增殖，促进细胞凋亡。Bestrophin 3可直接结合PI3K p110亚基,下调bestrophin 3抑制PI3K-Akt的活化。本研究拟在上述工作基础上，阐明bestrophin 3结合PI3K p110亚基进而调控PI3K-Akt信号及细胞增殖和凋亡的机制，并通过在体实验检测bestrophin 3敲除对高血压血管重构的影响。该工作将从细胞增殖和凋亡角度阐明bestrophin 3的新功能，提出bestrophin 3可能是调控PI3K-Akt信号通路关键分子的新观点，并为评估bestrophin 3是否可作为防治高血压血管重构新靶点提供实验室依据

本项目探讨了bestrophin 3在高血压血管重构中的作用，并从血管平滑肌细胞增殖和凋亡角度分析了其可能的作用机制。主要发现：1) bestrophin 3通过维持Bcl-2/Bax 的表达平衡，稳定线粒体膜电位，阻止线粒体凋亡信号通路活化，抑制血管平滑肌细胞凋亡；2) bestrophin 3是PI3K p110α亚基蛋白稳定性的关键内源性调节蛋白，bestrophin 3通过其C端与p110α亚基结合，抑制PI3K p110α经蛋白酶体通路降解，从而激活PI3K/Akt信号通路，上调细胞周期相关蛋白cyclin D1，cyclin E和CDK2的表达，下调细胞周期抑制蛋白p21和 p27的表达，加速细胞周期从G1期向S期转换，促进血管平滑肌细胞增殖；3) 球囊损伤颈动脉内膜增厚，炎性浸润增加，细胞外基质增多。同时新生内膜PI3Kp110α和Fibronectin的表达升高。转染bestrophin 3 RNA干扰腺病毒敲减bestrophin 3明显减轻上述病理性改变，新生内膜形成减少；4) bestrophin 3血管平滑肌特异性敲除小鼠，基础状态下其血管管壁变薄，细胞外基质减少。显微结构显示bestrophin 3缺失导致血管中层平滑肌细胞数量减少，弹力纤维表达降低。AngiotensinⅡ处理后，bestrophin 3血管平滑肌特异性敲除和对照组相比，血压无明显变化。但bestrophin 3敲除组主动脉夹层发生率从对照组的10%升高至87%。本课题工作明确了bestrophin 3是血管平滑肌细胞增殖和凋亡以及高血压血管重构的关键调控分子。发现bestrophin 3是PI3K p110亚基蛋白稳定性内源性调节蛋白。我们的工作揭示了bestrophin 3在血管平滑肌细胞的新功能，提示bestrophin 3是防治高血压血管重构等血管增生性疾病的新靶点。