Novel Mechanisms to Enhance Utrophin Expression and Muscle Cell Function

这个试点项目和可行性项目是由两项PI合作的同时发现的

This pilot and feasibility project culminated from two concurrent discoveries in a collaboration between the PI and the co-Pi that reveal novel mechanisms for up-regulating proteins that compensate for dystrophindeficiency. First, we identified a FDA-approved compound, compound 6, that increases glycosylation of glycoproteins at the muscle cell surface, which in turn 1) enhances muscle cell interaction with components of the extracellular matrix and 2) increases abundance of dystrophin- and utrophin-glycoprotein complexes. Serendipitously, we found that introduction of sarcospan, a small transmembrane component of the dystrophin-glycoprotein complex, has identical effects. Overexpression of sarcospan ameliorates dystrophy by stabilizing the utrophin-glycoprotein complex throughout the sarcolemma and increasing surface glycosylation. We propose to investigate mechanisms by which altered cell surface glycosylation enhances muscle cell function with the goal of developing these discoveries into therapies for DMD. We will identify the types of glycans that are modified by compound 6 treatment and sarcospan overexpression, as well as the glycoproteins that bear these modified glycans. We will investigate the roles of the modified glycoproteins in the enhanced binding of laminin that we have observed when muscle cells are treated with compound 6. We will interrogate the interaction of laminin with dystrophin- and utrophin-glycoprotein complexes on the surface of cells treated with compound 6, to understand how this drug alters subcellular localization and/or stability of these complexes. We will test the efficacy of compound 6 in the mdx mouse model as well as one other model of congenital muscular dystrophy. This application addresses the primary defect in DMD and other congenital muscular dystrophies, as the results of this work may be broadly applicable to congenital dystrophies resulting from defects in glycosylation, such as Walker-Warburg Syndrome, muscle-eye-brain disease, Fukuyama congenital muscular dystrophy, and congenital muscular dystrophies type-1 B, -1C and - 1D. This pilot and feasibility project will rely on expertise and services provided by Core B (High-throughput Screening), Core C (Muscle Phenotyping and Imaging), and Core D (Bioinformatics and Genomics).