Patho-Genetic Explorations of Myotilin, the LGMD1A Gene

描述(申请人提供)：Myotilin蛋白在肌肉中特异表达，并定位于肌纤维Z-Disc。两个独立的myotilin基因错义突变导致1A型肢体-Girdle肌营养不良症(LGMD1A)，两个独立的myottin错义单核苷酸多态(SNPs)显示与扩张型心肌病(DCM)正相关。这些突变导致的氨基酸替换发生在myotilin的N端，这是一个未知功能的区域。 为了探讨LGMD1A型突变对肌红素和肌肉功能的影响，我建议对LGMD1A型肌肉进行免疫组织化学，目标是Myotilin、myotilin相互作用蛋白，以及定位于肌纤维Z盘的其他蛋白。我建议构建三个突变的myotilin转基因基因，并彻底表征它们对转基因小鼠肌肉功能的影响。这样的小鼠还将为下游的免疫组织化学和生化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myotilin亚型，并继续在不断扩大的扩张型心肌病患者中对myotilin SNPs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.