Role of serum- and glucocorticoid-regulated kinase-1 in electrical remodeling

血清和糖皮质激素调节激酶 1 在电重构中的作用

• 批准号: 8206688
• 负责人: ANTHONY ROSENZWEIG
• 金额: $ 43.07万
• 依托单位: BETH ISRAEL DEACONESS MEDICAL CENTER
• 依托单位国家: 美国
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-01-15 至 2013-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8206688
• 关键词: 1-Phosphatidylinositol 3-Kinase; Action Potentials; Address; Arrhythmia; Binding; Cardiac; Cardiac Myocytes; Characteristics; Chronic; Data; Development; Dominant-Negative Mutation; Electrophysiology (science); Exhibits; Fibrosis; Functional disorder; Genetic; Genomics; Goals; Growth; Heart; Heart Hypertrophy; Heart failure; Hypertrophy; In Vitro; Investigation; Ion Channel; Kinetics; Maps; Mediating; Mediator of activation protein; Modeling; Molecular; Morbidity - disease rate; Mus; Mutagenesis; Myocardium; Optics; Pathway interactions; Patients; Phenotype; Phosphorylation; Phosphorylation Site; Phosphotransferases; Physiological; Play; Post-Translational Protein Processing; Potassium Channel; Protein-Serine-Threonine Kinases; Proteins; Proteomics; Relative (related person); Risk; Role; Sgk protein; Signal Transduction; Sodium; Sodium Channel; System; Testing; Tissues; Transgenic Mice; base; constriction; drug development; heart rhythm; in vivo; inhibitor/antagonist; interest; mortality; novel; novel therapeutic intervention; public health relevance; therapeutic target

DESCRIPTION (provided by applicant): Adverse cardiac remodeling is a common prelude to heart failure and arrhythmia, but little is known about the signaling mechanisms that mediate this transition. Serum- and glucocorticoid-regulated kinase-1 (SGK1) is a PI3-kinase (PI3K)-dependent kinase that is activated in pathological hypertrophy and heart failure (HF) but not in physiological hypertrophy. SGK1 shares some downstream substrates (e.g. GSK3 and Foxo3) with other PI3K-dependent kinases, such as Akt1, but also has unique downstream effects including modulation of ion channels such as potassium channels and the cardiac sodium channel, SCN5a. While we have previously shown that SGK1 regulates cardiomyocyte (CM) survival and growth in vitro, its role in CM in vivo and the effects of chronic SGK1 activation or inhibition are largely unknown. To address these questions in vivo, we generated cardiac-specific transgenic (TG) mice expressing either a constitutively active (CA) or dominant negative (DN) form of the SGK1 kinase. While SGK1-CA TG mice exhibit spontaneous and inducible arrhythmias, SGK1-DN TG mice appear normal at baseline. In a model of cardiac hypertrophy and heart failure induced by transverse aortic constriction (TAC), SGK1-DN TGs are substantially protected against cardiac dysfunction and fibrosis. SGK1 activation led to significant alterations in post-translational modification and subcellular distribution of SCN5a protein. This was associated with altered channel kinetics and gating, as well as an increase in late sodium current (INaL) and action potential duration (APD). The major goal of this proposal is to understand the role of SGK1 in electrical remodeling in the context of pathological hypertrophy and HF. This proposal is based on four hypotheses: 1) that chronic activation of SGK1 in CMs is an important mediator of adverse electrical remodeling in HF, 2) that inhibition of SGK1 in CMs will mitigate adverse remodeling, 3) that altered SCN5a function and INaL are important contributors to these effects, and 4) that other novel SGK1 substrates also play a role in the observed phenotypes. To test these hypotheses, we will utilize mice with CM-specific expression of SGK1-CA or -DN at baseline and in models of hypertrophy and/or HF. In Aim 1, we will examine the effects of activating or inhibiting SGK1 on electrical remodeling at baseline and after aortic banding. In Aim 2, we will define the cellular mechanisms responsible for the observed electrophysiological phenotypes. Finally, in Aim 3, we will delineate the molecular mechanisms mediating these phenotypes through focused interrogation of known downstream pathways, and subtractive screens for novel effectors. Arrhythmia remains an important cause of morbidity and mortality in HF. Understanding the role of SGK1 in adverse electrical remodeling and arrhythmic complications of HF could yield novel therapeutic approaches for this important condition. PUBLIC HEALTH RELEVANCE: Patients with heart failure or thickened (hypertrophied) heart muscle are at increased risk for heart rhythm problems, some of which can be fatal. Our goal is to understand the role of a specific molecule (SGK1) in the development of heart rhythm problems in this context. We will study this question in mice in which we have genetically activated or inhibited this molecule specifically in heart muscle cells. Our initial results suggest that activating this molecule promotes rhythm problems, whereas inhibiting it has beneficial effects. While we think it is important in general to understand mechanisms underlying heart rhythm problems, this molecule is particularly interesting because it belongs to a class of molecules that have previously been successfully targeted for drug development. Thus understanding SGK1's role in the heart could have important practical implications, and the current application would help advance our understanding of the potential of SGK1 as a therapeutic target.

描述（由申请人提供）：不良心脏重塑是心力衰竭和心律不齐的常见前奏，但对介导这种过渡的信号传导机制知之甚少。血清和糖皮质激素调节的激酶-1（SGK1）是一种PI3-激酶（PI3K）依赖性激酶，在病理肥大和心脏衰竭（HF）中被激活，但在生理肥大中却不是。 SGK1与其他依赖PI3K依赖性激酶（例如AKT1）共享一些下游底物（例如GSK3和FOXO3），但也具有独特的下游效应，包括对钾通道和心脏钠通道等离子通道的调节效应。 尽管我们以前已经表明，SGK1在体外调节心肌细胞（CM）存活和生长，但其在CM体内的作用以及慢性SGK1激活或抑制作用的作用在很大程度上是未知的。 为了在体内解决这些问题，我们产生了表达SGK1激酶的组成型活性（CA）或显性阴性（DN）形式的心脏特异性转基因（TG）小鼠。尽管SGK1-CA TG小鼠表现出自发性和诱导性心律不齐，但在基线时SGK1-DN TG小鼠显得正常。在由横向主动脉收缩（TAC）引起的心脏肥大和心力衰竭的模型中，SGK1-DN TGS受到基本保护，以防止心脏功能障碍和纤维化。 SGK1激活导致了SCN5A蛋白的翻译后修饰和亚细胞分布的显着改变。这与通道动力学和门控的改变有关，以及钠电流晚期（INAL）和动作电位持续时间（APD）的增加。该提案的主要目的是了解在病理肥大和HF的背景下，SGK1在电重塑中的作用。 该提议基于四个假设：1）CMS中SGK1的长期激活是HF中不良电重塑的重要介体，2）CMS中SGK1抑制SGK1在CMS中的抑制作用会缓解不良重塑，3）对SCN5A的功能和INAL的作用有影响，并且在这些效果中都会改变了其他效果。为了检验这些假设，我们将利用基线和肥大和/或HF模型的SGK1-CA或-DN的CM特异性表达的小鼠。在AIM 1中，我们将检查激活或抑制SGK1对基线和主动脉束带后电气化重塑的影响。在AIM 2中，我们将定义负责观察到的电生理表型的细胞机制。最后，在AIM 3中，我们将通过重点询问已知的下游途径的询问以及新型效应子的减法筛选来描述介导这些表型的分子机制。 心律不齐仍然是HF发病率和死亡率的重要原因。了解SGK1在HF的不良电重塑和心律不齐并发症中的作用可能会针对这种重要条件产生新颖的治疗方法。 公共卫生相关性：心力衰竭或心脏增厚（肥大）心肌的患者患心律问题的风险增加，其中一些可能是致命的。我们的目标是了解在这种情况下，特定分子（SGK1）在心律问题发展中的作用。我们将在小鼠中研究这个问题，其中我们在心脏肌肉细胞中特异性地激活或抑制了该分子。我们的最初结果表明，激活该分子会促进节奏问题，而抑制它具有有益的效果。尽管我们认为通常了解心律问题的机制通常很重要，但该分子特别有趣，因为它属于以前成功地用于药物开发的一类分子。因此，了解SGK1在心脏中的作用可能会产生重要的实际含义，当前的应用将有助于促进我们对SGK1作为治疗目标的潜力的理解。