Hippo/YAP通路在Ang-II诱导血管平滑肌细胞表型转换及高血压性血管重构中的作用及分子机制

Hypertensive vascular remodeling (HVR), characterized by media hyperplasia, is the independent risk factor of target organ damage and adverse prognosis in hypertension patients. Vascular smooth muscle cell (VSMC) phenotypic modulation is the key mechanism for media hyperplasia. Hippo/YAP pathway is an evolutionarily conserved molecular mechanism, which has been reported to participate in PDGF-BB-induced VSMC phenotypic modulation, and play a fundamental role in fetal vasculogenesis. However, the role of Hippo/YAP in HVR remains elusive. Our previous study demonstrated that the expression of YAP in the carotid artery was elevated in HVR rat model, accompanied with VSMC phenotypic modulation. We also found that in VSMC, Ang-II, the widely-accepted HVR-inducing factor, up-regulated the expression and promoted the nuclear accumulation of YAP. As a result, we hypothesize that, when activated by Ang-II, the Hippo/YAP pathway could induce VSMC phenotypic modulation and lead to HVR formation. This study aims to test this hypothesis and elucidate its molecular mechanism by a series of in vitro and in vivo experiments, such as sh-YAP adenovirus transfection, Co-IP, microarray and dual luciferase reporter assay. Our study will provide theoretical basis for Hippo/YAP pathway as a novel therapeutic target of HVR.

高血压性血管重构（HVR）主要表现为血管中膜增生，是高血压靶器官损害及不良预后的独立预测因子。而血管平滑肌细胞（VSMC）表型转换是中膜增生的关键机制。Hippo/YAP通路是高度保守的信号通路，在胚胎血管发育中发挥决定性作用，被PDGF-BB激活后可促VSMC表型转换，但其在HVR中的作用尚不清楚。我们的预实验发现，大鼠HVR模型颈动脉YAP表达明显上调，并表现出VSMC表型转换；公认的促HVR因子血管紧张素II（Ang-II）亦可上调VSMC YAP的表达并促进其向核内聚集（活化）。因此，我们提出科学假说：Hippo/YAP通路被Ang-II激活后，可能通过促进VSMC表型转换，最终诱导HVR形成。本课题拟采用sh-YAP腺病毒转染、免疫共沉淀、基因芯片、双荧光素酶报告系统等技术，通过体内外实验来验证假说并阐述其具体的分子机制。为Hippo/YAP通路做为HVR治疗靶点提供理论依据。

目前高血压呈流行态势，严重危害人类健康。高血压的危害在于各种靶器官损害。高血压性血管重构（Hypertensive Vascular Remodeling，HVR）是高血压靶器官损害的共同病理基础，主要表现为血管中膜增生，尤其是血管平滑肌细胞（Vascular smooth muscle cell，VSMC）异常增殖。临床研究证实，HVR是高血压患者不良预后的独立预测因子。目前HVR的分子机制尚不清楚。YAP（Yes‐associated protein）蛋白是Hippo/YAP通路的效应因子，已报道YAP调控细胞增殖和分化，参与血管发育。本课题通过持续输注血管紧张素II（Ang-II）构建HVR大鼠模型，构建sh-YAP腺病毒载体在体敲低YAP表达，证实下调YAP蛋白能明显减轻Ang-II 诱导的HVR，该作用独立于大鼠血压水平；体外实验发现，Ang-II呈剂量和时间依赖性上调VSMC中YAP的表达并促进其激活入核，最终促使VSMC表型转化，而下调YAP可以明显抑制Ang-II诱导的VSMC激活、迁移和表型转化；Ang-II上调YAP表达可以被AT1R抑制剂氯沙坦、F‐actin去聚剂latrunculin B以及YAP-TEAD转录复合物抑制剂verteporfin所抑制，而不能被AT2R抑制剂PD 123319所抑制，提示Ang-II通过AT1R、F-actin形成调控YAP表达，最后诱导YAP-TEAD转录复合物形成以调控下游基因表达并发挥YAP生物功能。本课题首次报道YAP介导Ang-II诱导VSMC表型转化以及HVR，有助于加深对非血压依赖性HVR的理解，为YAP作为HVR治疗靶点提供实验依据。