Department of Pathology and Laboratory Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA.
McAllister Heart Institute, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA.
Cells. 2020 Apr 22;9(4):1042. doi: 10.3390/cells9041042.
Anti-hypertensive therapies are usually prescribed empirically and are often ineffective. Given the prevalence and deleterious outcomes of hypertension (HTN), improved strategies are needed. We reported that the Rho-GAP GRAF3 is selectively expressed in smooth muscle cells (SMC) and controls blood pressure (BP) by limiting the RhoA-dependent contractility of resistance arterioles. Importantly, genetic variants at the GRAF3 locus controls BP in patients. The goal of this study was to validate GRAF3 as a druggable candidate for future anti-HTN therapies. Importantly, using a novel mouse model, we found that modest induction of GRAF3 in SMC significantly decreased basal and vasoconstrictor-induced BP. Moreover, we found that GRAF3 protein toggles between inactive and active states by processes controlled by the mechano-sensing kinase, focal adhesion kinase (FAK). Using resonance energy transfer methods, we showed that agonist-induced FAK-dependent phosphorylation at GRAF3 reverses an auto-inhibitory interaction between the GAP and BAR-PH domains. Y376 is located in a linker between the PH and GAP domains and is invariant in GRAF3 homologues and a phosphomimetic GRAF3 variant exhibited elevated GAP activity. Collectively, these data provide strong support for the future identification of allosteric activators of GRAF3 for targeted anti-hypertensive therapies.
抗高血压治疗通常是经验性的，往往效果不佳。鉴于高血压（HTN）的普遍性和有害后果，需要改进策略。我们报道了 Rho-GAP GRAF3 选择性地在平滑肌细胞（SMC）中表达，并通过限制 RhoA 依赖性阻力小动脉的收缩性来控制血压（BP）。重要的是，GRAF3 基因座的遗传变异控制着患者的血压。本研究的目的是验证 GRAF3 作为未来抗高血压治疗的可成药候选物。重要的是，使用一种新型小鼠模型，我们发现 SMC 中 GRAF3 的适度诱导可显著降低基础血压和血管收缩诱导的血压。此外，我们发现 GRAF3 蛋白通过由机械敏感激酶、黏着斑激酶（FAK）控制的过程在非活性和活性状态之间转换。使用共振能量转移方法，我们表明激动剂诱导的 FAK 依赖性 GRAF3 磷酸化逆转了 GAP 和 BAR-PH 结构域之间的自动抑制相互作用。Y376 位于 PH 和 GAP 结构域之间的连接子上，在 GRAF3 同源物中是不变的，并且磷酸模拟 GRAF3 变体表现出升高的 GAP 活性。总之，这些数据为未来鉴定 GRAF3 的别构激活剂以用于靶向抗高血压治疗提供了强有力的支持。
