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.

项目摘要 肌肉的有效收缩力需要含有肌动蛋白的蛋白质的适当组装、调节和激活。 细丝平滑肌样蛋白（Leiomodins，Lmods）是一类调节肌动蛋白组装的肌动蛋白结合蛋白 通过单一的原肌球蛋白结合和多个肌动蛋白结合域的细丝。我们之前发现 敲除和过表达心脏优势亚型（Lmod 2）改变了薄的长度， 纤维在体内并导致心肌病。我们广泛的初步数据表明，Lmod 2的影响 收缩功能-独立于肌动蛋白细丝长度调节。拥有众多独特的 实验工具在手，这项建议的目标是明确确定的机制， LMOD 2突变导致心力衰竭。 越来越清楚的是，Lmod蛋白质家族在肌肉功能中起着关键作用; 三种LMOD同种型中任何一种的突变都会导致使人衰弱的疾病。在本建议中，我们描述 人类已知的第一个LMOD 2突变。这种突变导致严重的新生儿扩张型心肌病。所有 与LMOD相关的疾病具有共同的潜在病理生理学，即由于 收缩性降低。LMOD基因家族中的大多数致病突变都是无意义的， 移码突变预测导致截短蛋白的表达。然而，在几乎所有的情况下， 疾病很少或没有LMOD蛋白表达。大量的初步数据表明，无义介导的 mRNA衰减是突变型LMOD 2蛋白丢失的基础，我们可以使用LMOD 2特异性 反义寡核苷酸 我们假设Lmod 2是一种多功能蛋白，通过以下途径影响心肌收缩力： 保持适当的细丝长度并积极地影响细丝的活化。我们提出了一个 多学科方法，利用体外测定的独特组合，患者特异性诱导多能 干细胞衍生的心肌细胞（iPSC-CM）和人类疾病的新模型，以实现两个特定的 目的集中于确定：1）Lmod 2的基本功能，特别是Lmod 2如何调节瘦蛋白， 细丝组装和它在心脏收缩力中的作用，以及2）为什么LMOD 2的人类突变会导致 缺乏蛋白质表达，蛋白质丢失如何导致疾病，以及是否恢复全长或截短 LMOD 2可以预防（挽救）心肌病的发作。阐明Lmod 2的体内功能将 为我们理解肌肉收缩提供了关键的缺失环节。此外，这些研究将有一个 对理解由以下原因引起的一系列疾病的病因学和潜在治疗方法产生了广泛的影响： LMOD基因家族的突变，以及其他涉及无义介导的mRNA的疾病 必需蛋白质的衰变。