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

基本信息

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
项目类别：
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

项目摘要

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.

项目概要肌肉的有效收缩力需要含有肌动蛋白的适当组装、调节和激活细丝。 Leiomodins (Lmods) 是调节肌动蛋白组装的肌动蛋白结合蛋白家族细丝通过单个原肌球蛋白结合域和多个肌动蛋白结合域。我们之前发现心脏主要亚型（Lmod2）的敲除和过度表达都会改变细长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。拥有众多独特的现有实验工具，该提案的目标是明确确定如何 LMOD2 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 亚型中任何一种的突变都会导致人类衰弱疾病。在这个提案中，我们描述了 LMOD2 中第一个已知的人类突变。这种突变会导致严重的新生儿扩张型心肌病。全部 LMOD 相关疾病具有共同的潜在病理生理学特征，即由于以下原因导致严重肌无力：收缩力降低。 LMOD 基因家族中的大多数致病突变都是无意义的或预计移码突变会导致截短蛋白质的表达。然而，在几乎所有情况下疾病很少或没有 LMOD 蛋白表达。大量的初步数据表明，无意义介导的 mRNA 衰减是突变 LMOD2 蛋白丢失的基础，我们可以使用 LMOD2 特异性来恢复该蛋白反义寡核苷酸。我们假设 Lmod2 是一种多功能蛋白，通过以下方式影响心肌收缩力：保持适当的细丝长度并积极影响细丝的激活。我们提出一个多学科方法利用体外测定、患者特异性诱导多能性的独特组合干细胞衍生的心肌细胞（iPSC-CM）和人类疾病的新模型可实现两个特定目标目标集中于确定：1) Lmod2 的基本功能，特别是 Lmod2 如何调节瘦素细丝组装及其在心肌收缩力中的作用，以及 2) 为什么人类 LMOD2 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 LMOD2 可以预防（挽救）心肌病的发作。阐明 Lmod2 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影响 LMOD 基因家族突变，以及涉及无义介导 mRNA 的其他疾病必需蛋白质的腐烂。