Patho-Genetic Explorations of Myotilin, the LGMD1A Gene

描述（由申请人提供）： 肌动素蛋白在肌肉中特异性表达并定位于肌纤维Z盘。肌球蛋白基因中的两个独立的错义突变导致1A型肢带肌营养不良症（LGMD 1A），两个独立的肌球蛋白错义单核苷酸多态性（SNP）显示与扩张型心肌病（DCM）正相关。由这些突变引起的氨基酸取代发生在肌肽的N-末端，一个没有已知功能的结构域。 为了探索LGMD 1A突变对肌球蛋白和肌肉功能的影响，我建议对LGMD 1A肌肉进行免疫组织化学，靶向肌球蛋白，肌球蛋白相互作用蛋白，以及定位于肌纤维Z盘的其他蛋白质。我建议构建三个突变myotilin转基因，并彻底表征其对转基因小鼠肌肉功能的影响。这样的小鼠还将为下游免疫组织化学和生物化学实验提供丰富的组织。我还将描述一种主要在心肌中表达的新型肌球蛋白亚型，并继续在扩大的DCM患者中对肌球蛋白SNP进行基因分型。

DESCRIPTION (provided by applicant): Myotilin protein is expressed specifically in muscle and localizes to the myofiber Z-disc. Two independent missense mutations in the myotilin gene cause Limb-Girdle Muscular Dystrophy Type 1A (LGMD1A), and two separate myotitin missense single nucleotide polymorphisms (SNPs) show a positive association with dilated cardiomyopathy (DCM). The amino acid substitutions resulting from these mutations occur at the N-terminus of myotilin, a domain with no known function. To explore the effects of the LGMD1A mutations on myotilin and muscle function, I propose to perform immunohistochemistry on LGMD1A muscle, targeting myotilin, myotilin-interacting proteins, and additional proteins that localize to the myofiber Z-disc. I propose to construct three mutant myotilin transgenes and thoroughly characterize their effects on muscle function in transgenic mice. Such mice will also provide a wealth of tissue for downstream immunohistochemical and biochemical experiments. I will also characterize a novel myotilin isoform that is expressed predominantly in cardiac muscle, and continue to genotype myotilin SNPs in an expanding set of DCM patients.