Mechanistic Basis of Cardiac Laminopathy

心脏核纤层病的机制基础

• 批准号: 10279393
• 负责人: Gregg G Gundersen
• 金额: $ 73.72万
• 依托单位: COLUMBIA UNIVERSITY HEALTH SCIENCES
• 依托单位国家: 美国
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-09-16 至 2025-06-30
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10279393
• 关键词: Actins; Affect; Biological Assay; Biological Models; Biology; Bundling; Cardiac; Cardiac Myocytes; Cardiomyopathies; Cell Nucleus; Cells; Complex; Contracts; Cytoskeleton; DNA Damage; Data; Defect; Dilated Cardiomyopathy; Disease; FHOD3 gene; Feedback; Fibroblasts; Functional disorder; Gene Abnormality; Gene Expression; Gene Mutation; Genes; Goals; Heart; Heart Diseases; Human; Inherited; Lamin Type A; Lead; Life; MAPK3 gene; Maintenance; Measures; Mechanical Stress; Mechanics; Mediating; Microfilaments; Movement; Mus; Mutation; Myocardial dysfunction; Nuclear; Nuclear Envelope; Nuclear Lamina; Nuclear Outer Membrane; Nuclear Structure; Pathogenesis; Pathogenicity; Pathology; Patients; Phenotype; Phosphorylation; Physiological; Physiology; Positioning Attribute; Process; Proteins; Research; Role; Rupture; Sarcomeres; Signal Pathway; Signal Transduction; Stress; Structural Protein; Testing; Variant; Wild Type Mouse; actin 2; checkpoint inhibition; design; env Gene Products; familial dilated cardiomyopathy; fundamental research; in vivo; induced pluripotent stem cell; live cell imaging; mechanical force; mouse model; novel; prevent; response; sensor

PROJECT SUMMARY Mutations in the lamin A/C gene (LMNA) encoding structural proteins of the nuclear lamina are responsible for up to ten percent of cases of inherited dilated cardiomyopathy. The disease is often referred to as cardiac laminopathy. Experimental evidence partially supports various pathogenic mechanisms of how defects in nuclear structural proteins cause cardiomyopathy, including that they lead to abnormalities in cell mechanical stability, dysregulation of gene expression and altered cell signaling. However, there is no unifying hypothesis integrating these defective processes and explaining exactly how they lead to cardiomyocyte damage and dysfunction. We recently found a surprising relationship between aberrant extracellular signal-regulated kinase 1/2 (ERK1/2) signaling and altered nuclear positioning in cardiac laminopathy. This has led us to hypothesize the existence of a mechanic checkpoint in which alterations in the nuclear lamina upregulate ERK1/2 activity, which causes mispositioning of the nucleus by phosphorylating and inactivating the actin bundling activity of the formin homology domain-containing protein (FHOD). Inactivation of FHOD prevents the linker of nucleoskeleton and cytoskeleton (LINC) complex, which spans the inner and outer nuclear membranes and connects to actin filaments, to mediate nuclear positioning. Normally, the mechanical checkpoint acts to prevent excessive force from being applied to the nucleus in contracting cardiomyocytes. However, with permanent alterations in nuclear structure resulting from LMNA mutations, the persistently activated checkpoint becomes maladaptive, resulting in abnormal nuclear positioning, nuclear envelope rupture, DNA damage and defects in sarcomere function. This Project is designed to prove the nuclear mechanical checkpoint hypothesis and determine its role in the pathogenesis of cardiac laminopathy. In Aim 1, we will examine how activation of the mechanical checkpoint for nuclear positioning alters cardiomyocyte biology. We will directly measure force on the nucleus using a nesprin- 2 actin tension sensor. As recent data suggest that the nucleus contributes to normal sarcomere, we will test the hypothesis that persistent mechanical checkpoint activation and nuclear mispositioning leads to defective sarcomere assembly and function in cardiomyocytes. In Aim 3, we will determine how altering the mechanical checkpoint affects the heart in vivo. We will test if expressing a phosphomimetic FOHD variant (checkpoint activation) in the heart induces cardiomyopathy in wild type mouse hearts and if a non-phosphorylatable variant (checkpoint inactivation) ameliorates pathology in a mouse model of cardiac laminopathy. Proving the existence of a novel nuclear mechanical checkpoint and establishing its role in the pathogenesis of cardiomyopathy caused by LMNA mutations will shift research directions in the field and potentially lead to new treatments for this life- threatening inherited heart disease.

项目摘要 编码核层的结构蛋白的层粘连蛋白A/C基因（LMNA）的突变是负责 多达十％的遗传性心肌病病例。该疾病通常被称为心脏 椎板病。实验证据部分支持核中缺陷的各种致病机制 结构蛋白会引起心肌病，包括它们导致细胞机械稳定性异常， 基因表达的失调和细胞信号改变。但是，没有统一的假设整合 这些有缺陷的过程，并准确地解释了它们如何导致心肌细胞损伤和功能障碍。我们 最近发现异常的细胞外信号调节激酶1/2（ERK1/2）之间存在惊人的关系。 心脏椎板病中的信号传导和核位置改变。这使我们假设 一个机械检查点，其中核薄片的改变会导致ERK1/2活性 通过磷酸化和灭活形式的肌动蛋白捆绑活性，对细胞核的定位错误 含同源域的蛋白质（FHOD）。 FHOD的失活阻止了核骨骼的接头和 细胞骨架（LINC）复合物，跨越内部和外核膜并连接到肌动蛋白 细丝，介导核定位。通常，机械检查点可以防止过多的力 从在收缩心肌细胞中应用于细胞核。但是，随着核的永久改变 LMNA突变导致的结构，持续激活的检查点变为不良适应性，导致 在异常的核位置，核包膜破裂，DNA损伤和肌节功能中的缺陷。这 项目旨在证明核机械检查点假设并确定其在 心脏椎板病的发病机理。在AIM 1中，我们将研究如何激活机械检查点 核定位改变了心肌细胞生物学。我们将使用内氏蛋白酶直接测量核上的力 2肌动蛋白张力传感器。由于最近的数据表明核有助于正常的肌节，我们将测试 持续的机械检查点激活和核位置的假设导致有缺陷 心肌细胞中的肌节组件和功能。在AIM 3中，我们将确定如何改变机械 检查点影响体内心脏。我们将测试是否表达磷酸化FOHD变体（检查点 在心脏中激活）在野生型小鼠心脏中诱导心肌病，如果是不可磷酸的变体 （检查点灭活）在心脏椎板病小鼠模型中改善病理。证明存在 新型的核机械检查点，并确定其在心肌病的发病机理中的作用 通过LMNA突变将改变该领域的研究方向，并有可能导致这种生命的新治疗方法 威胁性遗传性心脏病。