Hypertension: Role of Smooth Muscle Cullin-3 and the CRL3 Complex

 描述（由申请人提供）：泛素连接酶通过促进底物蛋白的泛素化来调节蛋白质周转，底物蛋白靶向其进行蛋白质体降解。CRL或Cullin-Ring泛素连接酶包括进化上保守的泛素连接酶的最大类别。Cullin-3（Cul 3）是该家族的成员之一，其在动脉压调节中起重要作用，因为编码Cul 3或Cul 3衔接蛋白的基因中的突变引起显性形式的高血压。我们发表的证据和初步数据支持一个新的概念，即血管平滑肌Cul 3在动脉血压调节中起着实质性的作用，其失调导致高血压。我们假设Cul 3是RhoA的调节剂，RhoA是一种小的GTdR，其控制Rho激酶活性、钙敏感性、一氧化氮反应性和血管平滑肌的收缩活性。重要的是，血管Cul 3的表达和作用在动脉压调节中的作用还有待研究。我们将测试血压调节的创新概念，部分通过血管平滑肌中的Cul 3依赖性途径。具体而言，我们假设a）Cul 3活性受损导致高血压，B）Cul 3突变体导致人高血压不能适当地泛素化Cul 3底物（如RhoA），以及c）Cul 3突变体通过干扰野生型内源性Cul 3而起主导作用。该项目的目的是：1）检验突变Cul 3在血管平滑肌中对野生型Cul 3的显性干扰以及Cul 3中血管平滑肌特异性缺陷导致血管功能受损和高血压的假设，以及2）探索Cul 3突变导致人类高血压导致Cul 3底物泛素化受损的分子机制。这些研究在推进蛋白质周转是血管平滑肌功能和动脉压调节的调节剂的概念，在机械上定义Cul 3突变如何引起人类高血压，并建立Cul 3活性受损导致高血压的机制方面具有重要意义。该项目的长期目标是评估Cul 3通路是否可以用作高血压的潜在治疗靶点。

 DESCRIPTION (provided by applicant): Ubiquitin ligases regulate protein turnover by promoting ubiquitination of substrate proteins which targets them for proteosomal degradation. CRL or Cullin-Ring ubiquitin Ligases comprise the largest class of evolutionarily conserved ubiquitin ligases. One member of this family, Cullin-3 (Cul3) plays an important role in arterial pressure regulation as mutations in the genes encoding Cul3 or Cul3 adaptor proteins cause dominant forms of hypertension. Our published evidence and preliminary data support a novel concept that vascular smooth muscle Cul3 plays a substantive role in arterial pressure regulation and its dysregulation causes hypertension. We hypothesize that Cul3 is a regulator of RhoA, a small GTPase which controls Rho kinase activity, calcium sensitivity, nitric oxide responsiveness, and contractile activity in vascular smooth muscle. Importantly, the role of vascular Cul3 expression and action in arterial pressure regulation has yet to be investigated. We will test the innovative concept that blood pressure is regulated, in part, through a Cul3-dependent pathway in vascular smooth muscle. Specifically, we hypothesize that a) impaired Cul3 activity causes hypertension, b) Cul3 mutants causing human hypertension do not properly ubiquitinate Cul3 substrates (such as RhoA), and c) Cul3 mutants act dominantly by interfering with wild-type endogenous Cul3. The aims of the project are to: 1) test the hypothesis that dominant interference of wildtype Cul3 by mutant Cul3 in vascular smooth muscle and vascular smooth muscle-specific deficiency in Cul3 results in impaired vasomotor function and hypertension, and 2) explore molecular mechanisms by which mutations in Cul3, which cause human hypertension result in impaired ubiquitination of Cul3 substrates. These studies are significant in advancing the concept that protein turnover is a regulator of vascular smooth muscle function and arterial pressure regulation, in mechanistically defining how mutations in Cul3 cause human hypertension, and in establishing mechanisms by which impaired Cul3 activity causes hypertension. The long term goal of this project is to assess if the Cul3 pathway can be used as a potential therapeutic target in hypertension.