Determining the role of Rac1 palmitoylation in cardiac hypertrophy and oxidative stress

项目总结 心血管疾病，包括心力衰竭，在美国和新的治疗方法中是导致死亡的主要原因 是更好地治疗这些疾病所需要的。心脏肥大是心脏变大的过程。 为了应对增加的工作量，尽管最初是适应性的，但这往往会导致心脏适应性不良 重塑，并参与几种心脏疾病的发病机制。Rho家族的小GTP酶rac1， 是心肌肥厚发展所必需的，并在心肌肥厚的发生、发展过程中起着重要的调节作用 心脏中的氧化应激作为NAPDH氧化酶2(NOX2)酶复合体的调节亚单位。两者都有 肥厚和氧化应激促进心力衰竭的进展，因此决定了新的 控制这些过程的监管机制是制药业非常感兴趣的。Rac1是 在Cys-178处发生棕榈酰化，促进其活化和膜靶向。棕榈酰化是一种可逆的 翻译后脂质修饰，动态调节蛋白质信号，已被证明是 在几种疾病状态下的病理信号所需的。重要的是，无论是遗传还是小分子 在临床前模型中，已有效地利用策略来靶向特定蛋白质的棕榈酰化。 癌症和炎症等疾病。然而，棕榈酰化在调节病理信号中的作用 在内心深处仍未受到考验。令人兴奋的是，我们的初步数据表明，rac1的基因抑制 棕榈酰化对新生大鼠心肌细胞(一种常见的体外心脏病模型)的保护作用 由过度活跃的rac1信号诱导的肥大和氧化应激。因此，我们假设 Cys-178上rac1的棕榈酰化作用将rac1靶向到膜上，在那里它被激活并诱导致病 信号部分是通过调节NOX2复合体实现的。该提案旨在确定rac1的功能 两种相关心脏模型在体内棕榈酰化调节心肌肥厚和氧化应激中的作用 肥大。我们将使用慢性血管内皮细胞输注心肌肥厚模型以及使用AAV- 介导的结构性活性rac1的过度表达，导致扩张型心肌病。在这些模型中， 我们将测试Cys-178突变为丝氨酸(C178S)的效果，丝氨酸不能被棕榈酰化为严格的丝氨酸 确定棕榈酰化在心肌肥厚和心肌氧化发展中的必要性 压力。这项工作的结果将第一次测试棕榈酰化依赖的信号在 调节心力衰竭的进展。这笔奖学金将为我提供成功所必需的训练。 作为制药行业的一名独立科学家，以及为我们共享的 有可能改善人类健康的科学知识。

PROJECT SUMMARY Cardiovascular disease, including heart failure, is the leading cause of mortality in the USA and new therapeutics are needed to better treat these diseases. Cardiac hypertrophy is the process by which the heart becomes larger in response to an increased workload and although initially adaptive, this often leads to maladaptive cardiac remodeling and is involved in the pathogenesis of several cardiac diseases. Rac1, a Rho family small GTPase, is required for the development of cardiac hypertrophy and relatedly plays an important role in mediating oxidative stress in the heart as a regulatory subunit of the NAPDH oxidase 2 (Nox2) enzyme complex. Both hypertrophy and oxidative stress promote the progression of heart failure and therefore determining novel regulatory mechanisms controlling these processes is of great interest to the pharmaceutical industry. Rac1 is palmitoylated at Cys-178 which promotes its activation and membrane targeting. Palmitoylation is a reversible post-translational lipid modification that dynamically regulates protein signaling and has been shown to be required for pathologic signaling in several disease states. Importantly, both genetic and small molecule strategies have been effectively utilized to target palmitoylation of specific proteins in pre-clinical models of diseases such as cancer and inflammation. However, the role of palmitoylation in regulating pathologic signaling in the heart remains untested. Excitingly, our preliminary data demonstrate that genetic inhibition of Rac1 palmitoylation protects neonatal rat cardiomyocytes, a common in vitro model of cardiac disease, from both hypertrophy and oxidative stress induced by hyperactive Rac1 signaling. Therefore, we hypothesize that palmitoylation of Rac1 at Cys-178 targets Rac1 to the membrane where it is activated and induces pathogenic signaling in part through regulation of the Nox2 complex. This proposal seeks to determine the function of Rac1 palmitoylation in regulating cardiac hypertrophy and oxidative stress in vivo using two relevant models of cardiac hypertrophy. We will use a chronic AngII infusion model of cardiac hypertrophy as well as a model using AAV- mediated overexpression of constitutively active Rac1, which causes dilated cardiomyopathy. In these models, we will test the effect of mutating Cys-178 to serine (C178S) which cannot be palmitoylated to rigorously determine the necessity of palmitoylation for the development of cardiac hypertrophy and myocardial oxidative stress. The results of this work will test, for the first time, a role for palmitoylation-dependent signaling in regulating the progression to heart failure. This fellowship will provide me with the training necessary to succeed as an independent scientist in the pharmaceutical industry as well as make significant contributions to our shared scientific knowledge that have the potential to improve human health.