Mechanistic Study of Cleaved Serum Response Factor in Cardiac Hypertrophy

心肌肥厚中血清反应因子裂解的机制研究

• 批准号: 8061975
• 负责人: Jiang Chang
• 金额: $ 25.64万
• 依托单位: TEXAS A&M UNIVERSITY HEALTH SCIENCE CTR
• 依托单位国家: 美国
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-04-15 至 2013-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8061975
• 关键词: 3' Untranslated Regions; Actins; Address; Adenoviruses; Architecture; Atrial Natriuretic Factor; Binding Sites; Biological Assay; Brain natriuretic peptide; Calmodulin; Cardiac; Cardiomyopathies; Caspase; Cells; Cleaved cell; Coupled; Development; Disease Progression; Dominant-Negative Mutation; Down-Regulation; Enhancers; Functional disorder; Gene Targeting; Generations; Genes; Genetic Transcription; Heart; Heart Diseases; Heart Hypertrophy; Heart failure; Histology; Human; Hypertrophic Cardiomyopathy; Hypertrophy; In Vitro; Laboratories; LacZ Genes; Link; Measurement; Mediating; Messenger RNA; MicroRNAs; Mitotic; Molecular; Morphology; Mus; Muscle Cells; Mutate; Myocardium; Myosin Heavy Chains; Outcome; Phenotype; Proteins; Regulatory Element; Reporter Genes; Role; Serum Response Factor; Stress; Testing; Time; Transgenic Mice; Transgenic Organisms; Untranslated Regions; Up-Regulation; caspase-3; chromatin immunoprecipitation; enhancing factor; in vivo; inhibitor/antagonist; mouse model; mutant; novel; nuclear factors of activated T-cells; pressure; promoter; public health relevance; research study; transcription factor

DESCRIPTION (provided by applicant): My recent study identified Serum response factor (SRF), an obligatory cardiogenic transcription factor, as a prominent caspase-3 target in human failing hearts. SRF cleavage led to the generation of a dominant negative inhibitor, SRF-N (N-terminus of SRF). This novel discovery is provocative, and raises the question of potential pathogenic role of SRF-N in cardiac dysfunction. To address this question, I generated multiple independent lines of transgenic mice that expressed SRF-N specifically in the heart. Mice with high expression level of SRF-N developed a dilated, hypertrophic cardiomyopathy and eventually died of heart failure. This provides a mouse model that mimics the progression of human heart disease. Microarray and quantitative PCR (Q-PCR) analyses revealed a significant downregulation of miR-133a and miR-1 in the SRF-N transgenic hearts, which coincided with overt upregulation of Mef2a, CaM and NFATc4. Together with recent discovery of RhoA and Cdc42 as miR-133a targets, we believe that the dysregulation of miR-133a and miR-1 and the consequent upregulation of a group of hypertrophy-associated genes may constitute one of the potential mechanisms contributing to SRF-N-mediated cardiomyopathy. These preliminary results underpin the application's central hypothesis that the dominant negative SRF-N directs the onset of cardiomyopathy and facilitates the progression to overt heart failure through the downregulation of miR-133a and miR-1 gene. Three aims are proposed. Aim I is to characterize the transgenic mouse phenotype. The transgenic mice will be assessed by comprehensive studies including functional, morphological and molecular assessments. Aim II and III are to elucidate the molecular mechanism of SRF-N-mediated cardiomyopathy. Dysregulation of the two cardiac microRNAs will be assessed. A group of miR-133a and miR-1 regulated target genes will be evaluated. Two new enhancers directed for miR-133a expression and one new target for miR-133a will be verified. Rescue experiments will be conducted to test if the introduction of miR-133a and -1 could correct/rescue the murine heart phenotype. The ultimate outcome of the application will be to establish a direct link between the dominant negative SRF-N and the development of heart failure. The novelty includes 1) the demonstration of SRF-N-mediated cardiomyopathy in intact heart; 2) the identification of two SRF-dependent enhancers regulating miR-133a expression; and 3) the elucidation of the molecular mechanism directing disease progression. PUBLIC HEALTH RELEVANCE: The study is focused on the mechanistic view of dominant negative cardiogenic transcription factor SRF-N (N-terminus of serum response factor) in propelling heart failure.

描述（由申请人提供）： 我最近的研究确定了血清反应因子（SRF），一个强制性的心源性转录因子，作为一个突出的caspase-3在人类心脏衰竭的目标。SRF切割导致产生显性负性抑制剂SRF-N（SRF的N-末端）。这一新的发现是挑衅性的，并提出了SRF-N在心功能不全中的潜在致病作用的问题。 为了解决这个问题，我产生了多个独立的转基因小鼠品系，这些小鼠在心脏中特异性表达SRF-N。高表达SRF-N的小鼠发生扩张型肥厚型心肌病，最终死于心力衰竭。这提供了一种模拟人类心脏病进展的小鼠模型。微阵列和定量PCR（Q-PCR）分析显示，在SRF-N转基因心脏中，miR-133 a和miR-1显著下调，这与Mef 2a、CaM和NFATc 4的明显上调相一致。结合最近发现的RhoA和Cdc 42作为miR-133 a的靶点，我们认为miR-133 a和miR-1的失调以及随之而来的一组肥大相关基因的上调可能构成了SRF-N介导的心肌病的潜在机制之一。这些初步结果支持了该申请的中心假设，即显性负性SRF-N指导心肌病的发作，并通过miR-133 a和miR-1基因的下调促进向明显心力衰竭的进展。 提出了三个目标。目的一是鉴定转基因小鼠的表型。转基因小鼠将通过综合研究进行评估，包括功能、形态和分子评估。目的二、三是阐明SRF-N介导心肌病的分子机制。将评估两种心脏microRNA的失调。将评价一组miR-133 a和miR-1调节的靶基因。两个新的针对miR-133 a表达的增强子和一个新的miR-133 a靶点将被验证。将进行挽救实验以测试miR-133 a和-1的引入是否可以校正/挽救鼠心脏表型。 该应用的最终结果将是建立显性阴性SRF-N与心力衰竭发展之间的直接联系。新奇包括：1）在完整心脏中证实了SRF-N介导的心肌病; 2）鉴定了两种调节miR-133 a表达的SRF依赖性增强子; 3）阐明了指导疾病进展的分子机制。 公共卫生关系： 本研究旨在探讨显性负性心源性转录因子SRF-N（血清反应因子N端）在心力衰竭中的作用机制。