CFTR与血管紧张素Ⅱ 1型受体结合调控高血压血管重构及药物影响

Ang II activating signaling pathway mediated by angiotensin type I receptor (AT1R) is an important drug target against hypertensive vascular remodeling. Our preliminary data found that, as blood pressure increased, the mRNA and protein levels of CFTR chloride channel decreased in the abdominal artery from hypertension patients and arteries from animal hypertension animal models with different mechanisms. In mice, deletion of CFTR promoted Ang II–induced increase in blood pressure, basilar arterial remodeling and proliferation of vascular smooth muscle cells (VSMCs). In VSMCs, knockdown of CFTR promoted Ang II-induced proliferation and upregulated proliferative signaling pathway downstream of AT1R, whereas overexpression of CFTR did the opposite. We also found that CFTR directly binds to the AT1R on the cell membrane. The overexpression of CFTR promotes the co-transport of CFTR-AT1R into cells. The present project aims to clarify the interaction between CFTR and AT1R, and how this interaction interferes with AT1R-mediated VSMC proliferation signaling pathway and thus regulates VSMC proliferation. Moreover, we will investigate the functional role of CFTR in hypertension-induced arterial proliferative remodeling in CFTR knockout mice. This study will reveal the new function of CFTR and raise the possibility that CFTR may be a key molecule regulating AT1R signal transduction through the formation of CFTR-AT1R heterodimers. This project will also provide important evidence to identify CFTR as a new therapy target against hypertensive vascular remodeling.

AngⅡ激活AT1R信号通路是防治高血压血管重构最重要的药物靶标。在国自然基金支持下，我们前期在高血压病人和高血压动物模型上发现，血管平滑肌CFTR表达随血压升高而下降，CFTR基因敲除促进血管平滑肌细胞增殖和AngⅡ诱导高血压过程中的脑血管重构。CFTR与AT1R在细胞膜上直接结合，过表达CFTR促进AT1R内化。本项目拟阐明CFTR通过与AT1R相互作用，调控AT1R表达、AT1R内化及细胞增殖的机制；并在整体模型上探讨CFTR与AT1R信号在高血压血管重构中内在相互关联的机制，及用药物干预CFTR-AT1R结合后对血管重构的影响。本研究将阐明血管平滑肌CFTR新功能，提出CFTR是调控AT1R信号内源性稳定分子的新观点，并从CFTR-AT1R蛋白复合体这一新角度，为寻找防治高血压血管重构新靶点提供线索。

本项目已基本按原计划研究内容按时完成，并达到预期研究目标。我们先前研究提示了CFTR氯通道与高血压发生发展及高血压脑血管重构密切相关。本项目通过应用CFTR基因敲除小鼠制备Ang Ⅱ诱导高血压模型，以及特异的siRNA 和腺病毒介导全长cDNA过表达等基因干预手段，并在高血压病人腹主动脉标本上进行验证，发现CFTR基因敲除促进高血压发生发展、血管平滑肌（VSMCs）增殖和脑血管重构。我们的研究结果表明：1）CFTR 可通过钙依赖性和非钙依赖性信号通路介导，调控脑VSMCs肌球蛋白轻链磷酸化，从而影响基础和高血压状态下脑基底动脉的收缩，为揭示CFTR参与高血压血管收缩功能的调控和调控高血压进程提供了实验依据和新机制；2）血管平滑肌CFTR 与AT1R存在相互作用，在给予Ang II刺激后，CFTR基因敲除可抑制β-arrestin2向胞膜上AT1R的募集以减少AT1R的内化，促进AT1R介导的VSMC增殖信号通路的持续激活，继而促进VSMC增殖，促进高血压血管重构。应用CFTR特异性抑制剂CFTRinh-172，发现药物干预CFTR通道功能后CFTR与AT1R的结合减少，且其下游的VSMC增殖信号通路上调。由此我们证实了CFTR是一个新的调控AT1R信号通路的负调节子。由于AngⅡ激活AT1R信号通路是防治高血压血管重构最重要的药物靶标，我们的研究结果提示，CFTR氯离子通道可成为防治高血压及高血压血管重构的新靶点，并可能成为干预病理性血管重构的新靶点和新策略。