Nesprin 1 and 2 in cardiac structure, function, and disease

描述（由申请人提供）： 外核膜蛋白Nesprin 1和2的突变可能参与Emery-Dreifuss肌营养不良症（EDMD）样表型的发病机制，包括心肌病和扩张型心肌病（DCM）。Nesprins属于一个新发现的血影蛋白重复蛋白家族，由四个成员组成。据信，Nesprin 1和2将细胞核锚到肌动蛋白丝上，并且广泛表达。为了研究Nesprin 1和2的功能，我们已经产生了Nesprin 1和2的floxed和全局敲除小鼠。我们的研究表明，Nesprin 2全基因敲除小鼠是可行的，没有明显的基础表型，而超过一半的Nesprin 1全基因敲除（Nesprin 1-/-）小鼠围产期死亡。剩余的Nesprin 1-/-幸存者在三个月大之前体重减轻，运动能力受损。与来自其他人的数据一致，我们已经发现在双敲除Nesprin 1和2的小鼠中100%的围产期致死率。Nesprin 1-/-小鼠和Nesprin 1和2双敲除小鼠骨骼肌的组织学分析显示非突触核的异常定位和突触核簇的消失。我们还观察到，Nesprin 1-/-小鼠显示异常的形状和定位的心肌细胞核。此外，我们观察到SUN 1的蛋白水平上调，Nesprin 1结合伴侣和内核膜蛋白，在Nesprin 1-/-心脏样本。这项为期5年的计划是通过分析突变小鼠及其衍生细胞来研究Nesprin 1和2在心脏核位置、核膜结构和心脏功能中的作用。我们在小鼠心肌细胞中基因消融Nesprins的独特能力，结合在整个动物、分离的乳头肌和培养的心肌细胞中测试分子和生理功能的能力，将为Nesprins在心脏结构、功能和疾病中的功能提供新的信息。 公共卫生相关性： 最近的数据表明，Nesprin 1和2的突变可能参与Emery-Dreifuss肌营养不良症（EDMD）样表型，包括心肌病和扩张型心肌病（DCM）的发病机制。我们的研究将有助于我们了解Nesprin 1和2在心脏结构和功能中的生物学功能。拟议的研究还将帮助我们深入了解Nesprin 1突变参与DCM发病机制的机制，从而提高我们对DCM的总体理解。

DESCRIPTION (provided by applicant): Mutations in the outer nuclear membrane proteins Nesprin 1 and 2 may be involved in the pathogenesis of Emery-Dreifuss muscular dystrophy (EDMD)-like phenotypes, including cardiomyopathy and dilated cardiomyopathy (DCM). Nesprins belong to a newly discovered family of spectrin-repeat proteins, composed of four members. Nesprin 1 and 2 are believed to anchor nuclei to actin filaments, and are ubiquitously expressed. To investigate functions of Nesprin 1 and 2, we have generated floxed and global knockout mice of both Nesprin 1 and 2. Our studies reveal that Nesprin 2 global knockout mice are viable and have no obvious basal phenotype, whereas over half of Nesprin 1 global knockout (Nesprin 1-/-) mice die perinatally. Remaining Nesprin 1-/- survivors have reduced body weight before three months of age and compromised exercise capacity. Consistent with data from others, we have found 100% perinatal lethality in double knockout mice for Nesprin 1 and 2. Histological analyses of skeletal muscle in Nesprin 1-/- mice and Nesprin 1 and 2 double knockout mice revealed abnormal positioning of non-synaptic nuclei and the disappearance of clusters of synaptic nuclei. We also observed that Nesprin 1-/- mice display abnormal shape and positioning of cardiomyocyte nuclei. In addition, we observed upregulation of protein levels of SUN1, a Nesprin 1 binding partner and an inner nuclear membrane protein, in Nesprin 1-/- heart samples. This 5 year proposal is to investigate the role of Nesprin 1 and 2 in cardiac nuclear position, nuclear membrane structure, and cardiac function by analysis of mutant mice and cells derived from them. Our unique ability to genetically ablate Nesprins in mouse cardiomyocytes, combined with the ability to test molecular and physiological functions in the whole animal, isolated papillary muscles, and cultured cardiomyocytes, will provide novel information as to the function of Nesprins in cardiac structure, function and disease. PUBLIC HEALTH RELEVANCE: Recent data suggest that mutations in Nesprin 1 and 2 may be involved in the pathogenesis of Emery-Dreifuss muscular dystrophy (EDMD)-like phenotypes including cardiomyopathy and dilated cardiomyopathy (DCM). Our proposed studies will help us to understand biological functions of Nesprin 1 and 2 in cardiac structure and function. The proposed studies will also help us gain insight into mechanisms by which mutations in Nesprin 1 are involved in the pathogenesis of DCM, thereby improving our general understanding of DCM.