Nuclear mechanics and mechanotransduction in muscular laminopathies

肌肉核纤层蛋白病的核力学和机械转导

• 批准号: 8842171
• 负责人: Jan Lammerding
• 金额: $ 39.65万
• 依托单位: CORNELL UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2007
• 资助国家: 美国
• 起止时间: 2007-01-01 至 2016-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8842171
• 关键词: Actins; Address; Adrenergic Agonists; Adult; Affect; Animals; Biological Assay; Biopsy; Cardiac; Cardiac Myocytes; Cell Death; Cell Nucleus; Cell physiology; Cells; Clinical Treatment; Congenital Heart Defects; Cytoplasm; Cytoplasmic Organelle; Cytoskeletal Proteins; Cytoskeleton; Data; Defect; Development; Dilated Cardiomyopathy; Disease; Drosophila genus; Drosophila melanogaster; Emery-Dreifuss Muscular Dystrophy; Event; Familial partial lipodystrophy; Fibroblasts; Gene Expression Regulation; Genes; Genetic; Goals; Health; Heart Contractilities; Heart Diseases; Heart Rate; Human; In Vitro; Inherited; Iowa; Lamin Type A; Lamins; Larva; Lead; Leg; Limb-Girdle Muscular Dystrophies; Link; Measures; Mechanical Stress; Mechanics; Modeling; Molecular; Muscle; Muscle Cells; Muscular Dystrophies; Mutate; Mutation; Myocardium; Myopathy; Normal tissue morphology; Nuclear; Nuclear Envelope; Nuclear Lamin; Nuclear Structure; Nuclear Translocation; Outcome; Pathway interactions; Patients; Phenotype; Play; Progressive Disease; Property; Proteins; Reporter; Reporting; Rupture; Serum Response Factor; Severities; Signal Pathway; Signal Transduction; Skeletal Muscle; Stress; Structure; Testing; Tissues; Universities; arm; design; disease phenotype; env Gene Products; factor A; fly; human disease; improved; in vivo; induced pluripotent stem cell; insight; lamin C; loris; mouse model; mutant; myocardin; novel; prevent; protein function; research study; response; transcription factor; wasting

DESCRIPTION (provided by applicant): More than one-third of all cases of dilated cardiomyopathy are caused by inherited mutations, with 5% to 10% of these mutations being linked to the LMNA gene, which encodes the nuclear envelope proteins lamin A and C. Importantly, mutations in the LMNA gene are also responsible for a broad spectrum of other diseases, including Emery-Dreifuss muscular dystrophy, limb-girdle muscular dystrophy and familial partial lipodystrophy. Despite recent advances, the mechanism(s) responsible for the often muscle-specific defects caused by different lamin mutations remains elusive. The central hypothesis of this proposal is that lamin mutations can cause skeletal and cardiac muscle disease through two, possibly overlapping mechanisms: (i) loss of structural function of lamins A and C, leading to rupture of the more fragile nucleus in mechanically stressed tissues; (ii) disturbing (mechanosensitive) signaling pathways that results in impaired function of muscle cells. Specific LMNA mutations may differentially affect these distinct aspects of lamin function, resulting in a broad spectrum of disease phenotypes. My long term goal is to understand the molecular mechanism(s) by which mutations in the nearly ubiquitously expressed lamins can lead to muscle-specific phenotypes and to explore to what extent impaired nuclear structure and altered cellular sensitivity to mechanical stress contribute to the muscle-specific phenotypes. In the first aim, we will test the hypothesis that altered nuclear mechanics result in increased nuclear rupture in mechanically stressed tissue. By using a genetic reporter assay that can detect even transiently compromised nuclear envelope integrity in cardiac myocytes in three mouse models of muscular laminopathies, we can directly assess whether mutations in nuclear envelope proteins cause increased rates of nuclear rupture in cardiac tissue. In the second aim, we will determine the relationship between impaired nuclear mechanics and the severity of muscular phenotypes in laminopathies. Using drosophila melanogaster models expressing a panel of lamin mutations with variable muscle involvement, we will relate effects of the mutations on the mechanical properties of nuclei in intact muscle tissue in drosophila larvae with the severity of muscle defects in adult flies. In the third aim, we will investigate the interplay between lamin mutations responsible for dilated cardiomyopathy and a specific signaling pathway, myocardin-related transcription factor A (MRTF-A). We will explore the mechanism(s) responsible for the impaired nuclear translocation of MRTF-A in lamin A/C-deficient and mutant cells we recently discovered and assess the functional consequences of impaired MRTF-A signaling on cellular function. Studying the effects of lamin mutations on nuclear structure and cellular signaling will improve our understanding of normal and tissue-specific functions of these proteins and lead to new insights into the molecular mechanisms responsible for dilated cardiomyopathy, Emery-Dreifuss muscular dystrophy and other laminopathies, potentially providing new targets for the treatment of these diseases.

描述（由申请人提供）：在所有扩张心肌病例中，超过三分之一是由遗传突变引起的，其中5％至10％与LMNA基因有关，LMNA基因的核包膜蛋白层层层粘结蛋白A和C。肢体束肌营养不良和家族性部分脂肪营养不良。尽管最近进展，但导致不同层粘连蛋白突变引起的肌肉特异性缺陷的机制仍然难以捉摸。该提议的中心假设是，层粘连蛋白突变会通过两种，可能重叠的机制引起骨骼和心肌疾病：（i）层粘连蛋白A和C的结构功能的丧失，导致机械压力的组织中较脆弱的核的破裂； （ii）干扰（机械敏感的）信号通路，导致肌肉细胞功能受损。特定的LMNA突变可能会差异地影响层粘连蛋白功能的这些不同方面，从而导致广泛的疾病表型。我的长期目标是了解分子机制，通过这种机制，几乎无处不在表达的粘液蛋白中的突变会导致肌肉特异性表型，并探索在多大程度上损害了核结构的程度，并改变了对机械应力的敏感性，从而有助于肌肉特异性表型。在第一个目的中，我们将检验以下假设，即改变核力学会导致机械压力组织中核破裂的增加。通过使用可以在三种肌肉椎板病小鼠模型中检测到心肌细胞中甚至可以瞬时损害的核包膜完整性的遗传记者测定法，我们可以直接评估核包膜蛋白中的突变是否会导致心脏组织中核破裂的速率增加。在第二个目标中，我们将确定核力学受损与椎板病中肌肉表型的严重程度之间的关系。使用果蝇黑色素司机模型，表达肌肉参与的层粘连蛋白突变，我们将将突变对果蝇幼虫中完整肌肉组织的机械性能的影响与成人果蝇中肌肉缺陷的严重程度联系起来。在第三个目标中，我们将研究负责扩​​张心肌病的层固定层突变与特定的信号通路，肌动蛋白相关的转录因子A（MRTF-A）。我们将探索负责MRTF-A/C缺陷和突变细胞中MRTF-A核转运受损的机制，我们最近发现并评估了MRTF-A信号受损对细胞功能的功能后果。研究层蛋白突变对核结构和细胞信号传导的影响将提高我们对这些蛋白质正常和组织特异性功能的理解，并导致对负责扩张性心肌病的分子机制的新见解，促进性心肌疗法，默里 - 雷氏肌营养不良症肌营养不良症和其他腹腔炎，并可能提供新的障碍，从而为这些障碍提供新的疾病。