Role of ATM in Cardiac Myocyte Loss and Myocardial Remodeling

ATM 在心肌细胞丢失和心肌重塑中的作用

• 批准号: 7531442
• 负责人: KRISHNA SINGH
• 金额: $ 21.3万
• 依托单位: EAST TENNESSEE STATE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2008
• 资助国家: 美国
• 起止时间: 2008-08-01 至 2010-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7531442
• 关键词: 1-Phosphatidylinositol 3-Kinase; ATM Gene Mutation; ATM deficient; ATM gene; Address; Adenoviruses; Adrenergic Receptor; Adult; Alleles; Apoptosis; Apoptotic; Ataxia Telangiectasia; Caliber; Cardiac; Cardiac Myocytes; Cell Cycle Checkpoint; Cell Death; Cells; Cessation of life; Chronic; DNA Repair; Data; Development; Disease; EFRAC; Embryo; Fibroblasts; Fibrosis; Functional disorder; Gene Expression; Gene Transfer; Genes; Genomic Instability; Heart; Heart failure; Hereditary Disease; Histology; Human; Immunologic Deficiency Syndromes; In Vitro; Individual; Infiltration; Inflammation; Inflammatory Response; Infusion procedures; Inherited; Integrins; Isoproterenol; Knock-out; Left; Left Ventricular Function; Malignant Neoplasms; Mediating; Modeling; Molecular Target; Morphology; Mus; Muscle Cells; Myocardial; Myocardial Infarction; Myocardial Ischemia; Myocardium; Necrosis; Nerve Degeneration; Oxidative Stress; Pathway interactions; Patients; Phenotype; Phosphorylation; Play; Predisposition; Premature aging syndrome; Proliferating; Protein Kinase; Protein p53; Public Health; Regulation; Research Design; Reverse Transcriptase Polymerase Chain Reaction; Role; Signal Pathway; Signal Transduction; Symptoms; Systemic disease; TP53 gene; Techniques; Testing; Ventricular; Ventricular Remodeling; Western Blotting; Wild Type Mouse; ataxia telangiectasia mutated protein; in vivo; inhibitor/antagonist; insight; macrophage; therapeutic target

DESCRIPTION (provided by applicant): Ataxia telangiectasia (A-T) results from mutation of the ATM gene. Individuals with an ATM mutation in one allele are spared from most of the symptoms of the disease, but are more susceptible to cancer and ischemic heart disease. ATM gene encodes a protein kinase which is suggested to be a key regulator of signaling cascades involved in cell cycle checkpoints, DNA repair and apoptosis. Evidence has been provided that inhibition of ATM induces a switch from apoptosis to necrosis in murine embryonic fibroblasts. Cardiac myocyte loss due to apoptosis and necrosis plays a significant role in the development of contractile dysfunction in the failing heart. Regulation of ATM gene expression and activity in postmitotic cardiac myocytes, and its role in apoptosis, necrosis and myocardial remodeling is not known. Analysis of differential expression of apoptosis-related genes using Gene-Array technique (preliminary data) revealed that 2-AR stimulation increases ATM gene expression. RT-PCR, western blot and immunocytochemical analyses demonstrated increased ATM expression in isolated adult cardiac myocytes and heart after 2-AR stimulation and myocardial infarction. 2-AR stimulation increased p53 protein (a downstream target of ATM) levels in the heart, and inhibition of ATM and p53 reduced 2-AR-stimulated apoptosis. Other preliminary data obtained using ATM deficient mice and chronic 2-AR-stimulation as a model of myocardial remodeling demonstrated that deficiency of ATM decreases left ventricular (LV) percent fractional shortening and ejection fraction, and increases LV end-systolic diameter and fibrosis. Increased myocardial fibrosis indicates increased cardiac cell necrosis and inflammation. Preliminary data suggested increased macrophage infiltration in the myocardium and increased necrosis in myocytes isolated from the myocardium of ATM deficient mice as compared to wild-type (WT) mice following 2-AR stimulation. These observations have led to our hypothesis that increased ATM expression and activity plays a pro-apoptotic role via p53-dependent mechanism/s. Deficiency of ATM induces a switch from cardiac myocyte apoptosis to necrosis leading to increased susceptibility to ischemic heart disease. Aim 1 will determine in vivo the role of ATM in myocardial remodeling using (WT) and ATM deficient mice subjected to A) isoproterenol infusion, B) myocardial infarction. Aim 2 studies will provide an insight into the mechanism by which ATM modulates cardiac cell death (necrosis and apoptosis) using myocytes isolated from the myocardium of adult WT and ATM deficient mice. Aim 3 will investigate the proximal signaling pathway (21-AR-Gs and GSK-32-JNKs) leading to increased expression and activity of ATM using pharmacological inhibitors and adenovirus-mediated gene transfer. These studies may help to uncover therapeutic targets to treat ischemic heart disease in AT patients. PUBLIC HEALTH RELEVANCE: Loss or inactivation of ATM protein in the human genetic disorder ataxia-telangiectasia (AT) leads to pleiotropic phenotype, including neuronal degeneration, immunodeficiency, genomic instability, premature aging and cancer predisposition. Individuals with an ATM mutation in one allele are spared from most of the symptoms of the disease, but are more susceptible to cancer and ischemic heart disease. The proposed studies, designed to investigate the role of ATM in cardiac myocyte loss and myocardial remodeling, could identify molecular targets to treat ischemic heart disease in AT patients.

描述（由申请人提供）：Ataxia毛细血管扩张症（A-T）由ATM基因突变引起。在一个等位基因中有ATM突变的个体不会出现这种疾病的大部分症状，但更容易患癌症和缺血性心脏病。ATM基因编码一种蛋白激酶，该蛋白激酶被认为是参与细胞周期检查点、DNA修复和凋亡的信号级联反应的关键调节因子。已有证据表明，抑制ATM可诱导小鼠胚胎成纤维细胞从凋亡转变为坏死。心肌细胞凋亡和坏死导致的心肌细胞损失在衰竭心脏收缩功能障碍的发展中起着重要作用。有丝分裂后心肌细胞中ATM基因表达和活性的调控及其在细胞凋亡、坏死和心肌重构中的作用尚不清楚。利用基因阵列技术分析凋亡相关基因的差异表达（初步数据）发现，2-AR刺激增加了ATM基因的表达。RT-PCR、western blot和免疫细胞化学分析显示，2-AR刺激和心肌梗死后，离体成人心肌细胞和心脏中ATM表达增加。2-AR刺激增加了心脏中p53蛋白（ATM的下游靶点）的水平，抑制ATM和p53可减少2-AR刺激的细胞凋亡。使用ATM缺陷小鼠和慢性2- ar刺激作为心肌重构模型获得的其他初步数据表明，ATM缺陷降低左室（LV）分数缩短百分比和射血分数，并增加左室收缩末期直径和纤维化。心肌纤维化增加表明心肌细胞坏死和炎症增加。初步数据显示，与野生型（WT）小鼠相比，在2-AR刺激后，ATM缺陷小鼠心肌中巨噬细胞浸润增加，肌细胞坏死增加。这些观察结果支持了我们的假设，即增加的ATM表达和活性通过p53依赖机制起促凋亡作用。ATM缺乏诱导心肌细胞凋亡向坏死转变，从而增加对缺血性心脏病的易感性。目的1将在体内确定ATM在心肌重构中的作用，使用（WT）和ATM缺陷小鼠进行A)异丙肾上腺素输注，B)心肌梗死。目的2研究将利用从成年WT和ATM缺陷小鼠心肌中分离的肌细胞，深入了解ATM调节心肌细胞死亡（坏死和凋亡）的机制。目的3将通过药物抑制剂和腺病毒介导的基因转移研究导致ATM表达和活性增加的近端信号通路（21-AR-Gs和GSK-32-JNKs）。这些研究可能有助于发现治疗缺血性心脏病AT患者的治疗靶点。公共卫生相关性：人类遗传性疾病共济失调-毛细血管扩张症（AT）中ATM蛋白的缺失或失活导致多种表型，包括神经元变性、免疫缺陷、基因组不稳定、早衰和癌症易感性。在一个等位基因中有ATM突变的个体不会出现这种疾病的大部分症状，但更容易患癌症和缺血性心脏病。本研究旨在探讨ATM在心肌细胞损失和心肌重塑中的作用，从而确定治疗AT患者缺血性心脏病的分子靶点。