Differential Methylation of Complex Pathophysiological Processes in Golden Retriever Muscular Dystrophy

Abstract

The purpose of this work was to survey DNA methylation along the canine genome within the context of Golden Retriever Muscular Dystrophy (GRMD) and look for associations. GRMD is the canine homolog to the human disease, Duchenne Muscular Dystrophy (DMD). These diseases are characterized by progressive muscle wasting, and clinical manifestations exist on a wide spectrum. GRMD and DMD are known as dystrophinopathies because they are caused by mutations in the gene that codes for the protein, dystrophin. While dysfunctional dystrophin is the root of the disease, there are other complex and interlinked pathophysiological processes involved that control muscle cell degeneration and regeneration, significantly influencing symptoms. We analyzed the methylation profiles of GRMD-afflicted (n=5) and healthy (n=6) dogs from tissue of the relatively atrophy-spared cranial sartorius muscle through reduced representation bisulfite sequencing (RRBS) and subsequent data processing. We that found base-pair level differences in methylation (differentially methylated sites, DMSs) between GRMD and normal dogs were associated with molecular mechanisms that are involved in the pathogenesis of dystrophinopathy, but not the dystrophin gene itself. We postulate that some of these mechanisms may be acting to compensate for dystrophin loss, contributing to the spared phenotype of the cranial sartorius muscle. We also suspect that other molecular processes previously unaffiliated with dystrophinopathy may play a role. These findings must be substantiated by later analyses of larger sample sizes and comparative analyses with gene transcripts.