Modulating Calcineurin Signaling Pathways in Muscle

肥厚性和缺血性心脏病已经达到流行病的比例，在这个国家和全球。 因此，迫切需要新的和更有效的治疗方法。钙调神经磷酸酶是一种钙调节蛋白， 在压力下促进心脏肥大生长和重塑的蛋白磷酸酶。我们 一个实验室发现了一个最近被重新命名为钙调神经磷酸酶调节因子的RCAN蛋白家族。我们 证明RCAN结合并抑制心脏和骨骼肌中的钙调磷酸酶活性。我们发现 转基因小鼠中RCAN 1表达的增加通过以下方式保护心脏免受各种应激： 减缓心肌梗死后的肥大生长和心力衰竭的进展。的战略 因此，增加心脏中RCAN的表达或活性可能具有治疗的临床价值 和预防心脏病。本提案是对我们的RO 1的竞争性更新，标题为“调制 肌肉中的钙调神经磷酸酶信号通路。“我们最初目标的实现大大有助于 了解RCAN对钙调神经磷酸酶的调节及其生物学意义。我们的发现 我们在激动人心的新方向，可能联系调节钙调神经磷酸酶的RCAN 1缺氧或氧化应激 应答重要的是，我们和其他人最近发现，心脏的梗塞面积更大。 缺血再灌注（I/R）后缺乏RCAN 1的小鼠。总之，这些发现表明，RCAN 1既可以 限制压力超负荷引起的肥大性生长，减少I/R造成的损伤。我们的新目标 解决了这些发现中产生的重要问题。具体目标1：确定 CAATT/增强子结合蛋白β（C/EBPb）在调节RCAN1.4表达中的作用， 参与心脏的肥大性重塑。在本节中，我们将测试 C/EBPb，其响应于心脏缺氧而被激活，以控制RCAN1.4表达并确定 C/EBPb活性是否影响钙调磷酸酶信号传导或心肌肥大。具体目标2：定义 RCAN 1亚型与泛素/蛋白酶体系统的相互作用，并测试这些 在心肌细胞肥大的情况下贡献同种型特异性功能。我们已经确定 两种不同类型的泛素连接酶复合物，与一种RCAN 1亚型特异性相互作用，但不与 其他. cullin 4A E3连接酶复合物（Cul 4A）与RCAN 1.4相互作用，而Von Hippel-Lindau因子 (VHL)缺氧反应的一个组成部分，与RCAN1.1相互作用。具体目标3：定义 RCAN 1保护心肌细胞免受氧化损伤的机制。的该部分中 我们将使用体外和体内技术来测试RCAN 1是否保护心肌细胞 并评估目标1和2中研究的机制在这一过程中的参与情况。 这些研究旨在阐明RCAN 1的机制，调节和生理作用，并创造 心脏病的治疗和预防的新的治疗方法的基础。导致心力衰竭的心血管疾病是美国的主要死亡原因， 尽管应用了最先进的疗法，但患病率仍在增加。显然需要 开发新的疗法。这一建议将提供有关一个家庭的重要信息， 保护心脏的内源性蛋白质称为钙调神经磷酸酶调节剂（RCAN）。这些研究将 阐明RCAN蛋白的作用机制、调控和生理作用，为研究RCAN蛋白的新功能奠定基础。 调节钙调神经磷酸酶的治疗方法，钙调神经磷酸酶是一种参与多种疾病进展的蛋白质， 包括心脏病和老年痴呆症的病理学。

Hypertrophic and ischemic heart disease has reached epidemic proportions both in this country and globally. As a result, there is urgent need for new and more effective therapies. Calcineurin is a calcium-regulated protein phosphatase that promotes hypertrophic growth and remodeling of the heart under stress. Our laboratory identified a family of proteins recently renamed RCANs for Regulators of Calcineurin. We demonstrated that RCANs bind to and inhibit calcineurin activity in heart and skeletal muscle. We showed that increased expression of RCAN1 in transgenic mice protects the heart from a wide variety of stresses by blunting both hypertrophic growth and the progression to heart failure after myocardial infarction. Strategies to increase the expression or activity of RCANs in the heart may therefore have clinical value for the treatment and prevention of heart disease. This proposal is a competitive renewal of our RO1 entitled "Modulating Calcineurin Signaling Pathways in Muscle." Accomplishment of our initial goals has contributed significantly toward understanding RCAN's regulation of calcineurin and its biological significance. Our findings have taken us in exciting new directions that may link regulation of calcineurin by RCAN1 to hypoxic or oxidative stress responses. Importantly, we, and others, have recently found that the area of infarct is larger in the hearts of mice lacking RCAN1 after ischemic-reperfusion (I/R). Together these findings suggest that RCAN1 can both limit hypertrophic growth in response to pressure overload and reduce damage from I/R. Our new goals address important questions that have grown out of these findings. Specific Aim 1: To determine the role of the CAATT/enhancer binding protein beta (C/EBPb) in regulating RCAN1.4 expression and test its involvement in hypertrophic remodeling of the heart. In this section we will test the ability of C/EBPb, which is activated in response to cardiac hypoxia, to control RCAN1.4 expression and determine whether C/EBPb activity influences calcineurin signaling or cardiac hypertrophy. Specific Aim 2: To define interactions of RCAN1 isoforms with the ubiquitin/proteasome system and to test whether these contribute isoform-specific functions in the setting of cardiomyocyte hypertrophy. We have identified two different classes of ubiquitin ligase complexes that interact specifically with one RCAN1 isoform but not the other. A cullin 4A E3 ligase complex (Cul4A) interacts with RCAN1.4, whereas the Von Hippel-Lindau factor (VHL), an integral component of hypoxic responses, interacts with RCAN1.1. Specific Aim 3: To define mechanisms through which RCAN1 protects cardiomyocytes from oxidative damage. In this portion of the proposal we will use both in vitro and in vivo techniques to test whether RCAN1 protects cardiac myocytes from oxidative damage and assess the involvement of mechanisms studied in Aims 1 and 2 in this process. These studies are designed to clarify the mechanism, regulation and physiological role of RCAN1 and create the basis for novel therapeutic approaches to the treatment and prevention of heart disease. Cardiovascular disease leading to heart failure is the leading cause of death in the Unites States and is increasing in prevalence despite the application of state-of-the-art therapies. There is a clear need for the development of new therapies. This proposal will provide important information regarding a family of endogenous proteins that protect the heart called Regulators of Calcineurin (RCANs). These studies will clarify the mechanism, regulation and physiological role of RCAN proteins and create the basis for novel therapeutic approaches to regulating calcineurin, a protein involved in the progression of a wide range of pathologies including heart disease and Alzheimers.