Deciphering the role of Lmod2 in cardiac muscle and in dilatedcardiomyopathy

解读 Lmod2 在心肌和扩张型心肌病中的作用

• 批准号: 10917836
• 负责人: Carol C Gregorio
• 金额: $ 56.14万
• 依托单位: ICAHN SCHOOL OF MEDICINE AT MOUNT SINAI
• 依托单位国家: 美国
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-04-01 至 2025-01-31
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10917836
• 关键词: Actin-Binding Protein; Actins; Actomyosin; Affect; Antisense Oligonucleotides; Binding; Biochemistry; Cardiac; Cardiac Myocytes; Cardiomyopathies; Cellular biology; Clinical; Complementary DNA; Data; Dilated Cardiomyopathy; Disease; Etiology; Family; Family member; Frameshift Mutation; Functional disorder; Funding; Future; Gene Family; Generations; Genes; Genetic; Goals; Hand; Heart; Heart failure; Human; Impairment; Intestines; Knock-out; Knockout Mice; Lead; Length; Link; Maintenance; Mechanics; Mediating; Messenger RNA; Microfilaments; Molecular Biology; Mus; Muscle; Muscle Contraction; Muscle Weakness; Muscle function; Mutation; Myocardium; Myopathy; Nemaline Myopathies; Neonatal; Nonsense Mutation; Patients; Physiological; Play; Predisposition; Process; Protein Binding Domain; Protein Family; Protein Isoforms; Protein Truncation; Proteins; RNA Splicing; Regulation; Role; Skeletal Muscle; Smooth Muscle; Structure; Syndrome; Terminator Codon; Therapeutic Intervention; Thin Filament; Transcript; Tropomyosin; Work; clinically relevant; design; disease-causing mutation; heart function; human disease; human model; improved; in vitro Assay; in vivo; induced pluripotent stem cell; induced pluripotent stem cell derived cardiomyocytes; insight; interdisciplinary approach; mRNA Decay; mouse model; mutant; neonate; novel; overexpression; premature; prevent; protein expression; spatial relationship; tool

PROJECT SUMMARY Effective contractile force in muscle requires the proper assembly, regulation, and activation of actin-containing thin filaments. Leiomodins (Lmods) are a family of actin-binding proteins that regulate assembly of actin filaments through a single tropomyosin-binding and multiple actin-binding domains. We previously discovered that both knockout and overexpression of the cardiac predominant isoform (Lmod2) alters the lengths of thin filaments in vivo and results in cardiomyopathy. Our extensive preliminary data suggest that Lmod2 impacts contractile function - independent of actin-thin filaments length regulation. With a plethora of unique experimental tools in hand, the goal of this proposal is to definitively determine the mechanisms of how mutations in LMOD2 lead to heart failure. It is becoming increasingly clear that the Lmod family of proteins play a critical role in muscle function; mutations in any of the three LMOD isoforms lead to debilitating human diseases. In this proposal, we describe the first known human mutation in LMOD2. This mutation leads to severe neonatal dilated cardiomyopathy. All LMOD-linked diseases have the common underlying pathophysiology of severe muscle weakness due to reduced contractility. Most of the disease-causing mutations in the LMOD gene family are nonsense or frameshift mutations predicted to result in expression of truncated proteins. However, in nearly all cases of disease little to no LMOD protein is expressed. Extensive preliminary data suggests that nonsense-mediated mRNA decay underlies the loss of mutant LMOD2 protein, which we can restore using LMOD2-specific antisense oligonucleotides. We hypothesize that Lmod2 is a multifunctional protein that influences cardiac contractility through maintaining proper thin filament lengths and positively effecting activation of the thin filament. We propose a multidisciplinary approach utilizing a unique combination of in vitro assays, patient-specific induced pluripotent stem cell-derived cardiomyocytes (iPSC-CMs), and novel models of human disease to accomplish two Specific Aims focused on determining: 1) the fundamental function(s) of Lmod2, particularly how Lmod2 regulates thin filament assembly and what role it has in cardiac contractility, and 2) why human mutations in LMOD2 lead to a lack of protein expression, how loss of protein leads to disease, and whether restoring full-length or truncated LMOD2 can prevent (rescue) the onset of cardiomyopathy. Elucidating the in vivo function(s) of Lmod2 will provide critical missing links in our understanding of muscle contraction. In addition, these studies will have a broad impact on understanding the etiology and potential treatments of a spectrum of diseases that result from mutations in the LMOD family of genes, as well as other diseases that involve nonsense-mediated mRNA decay of essential proteins.

项目总结 肌肉中有效的收缩力量需要含有肌动蛋白的适当组装、调节和激活。 细丝。Leiomodins(Lmods)是一个肌动蛋白结合蛋白家族，调节肌动蛋白的组装。 细丝通过单一的原肌球蛋白结合域和多个肌动蛋白结合域。我们之前发现 心脏优势亚型(Lmod2)的敲除和过表达都会改变Thin的长度 体内的细丝，并导致心肌病。我们广泛的初步数据表明，Lmod2影响 收缩功能-独立于肌动蛋白-细丝长度调节。有太多独特的 有了实验工具，这项提议的目标是最终确定 LMOD2基因突变会导致心力衰竭。 越来越清楚的是，Lmod蛋白家族在肌肉功能中发挥着关键作用； 三种LMOD亚型中的任何一种突变都会导致人类虚弱的疾病。在这份提案中，我们描述了 LMOD2基因的首个已知人类突变。这种突变会导致严重的新生儿扩张型心肌病。全 与LMOD相关的疾病具有共同的潜在病理生理学特征，即严重的肌肉无力是由于 收缩能力降低。大多数LMOD基因家族的致病突变都是无稽之谈或 移码突变预测会导致截短蛋白的表达。然而，在几乎所有的情况下 疾病很少或根本没有LMOD蛋白表达。大量的初步数据表明，胡说八道 突变的LMOD2蛋白的丢失是由mRNA的衰退引起的，我们可以使用LMOD2的特异性来恢复这种蛋白 反义寡核苷酸。 我们假设Lmod2是一种多功能蛋白，通过 保持适当的细丝长度，对细丝的激活有积极的影响。我们提出了一个 多学科方法，利用独特的体外分析组合，患者特定的诱导多能性 干细胞来源的心肌细胞(IPSC-CMS)和新的人类疾病模型完成两个特定的 目的集中在确定：1)Lmod2的基本功能(S)，特别是Lmod2是如何调节Thin的 细丝组装及其在心脏收缩能力中的作用，以及2)为什么人类LMOD2突变导致 缺乏蛋白质表达，蛋白质丢失如何导致疾病，以及是恢复全长还是截断 LMOD2可以预防(挽救)心肌病的发生。阐明Lmod2的体内功能(S)Will 提供我们对肌肉收缩理解中缺失的关键环节。此外，这些研究将有一个 对了解由以下原因引起的一系列疾病的病因和可能的治疗方法产生广泛影响 LMOD基因家族的突变，以及其他涉及无义介导的mRNA的疾病 必需蛋白质的腐烂。