Drivers of Repeat Instability in Myotonic Dystrophy

About This Grant

Project Summary Myotonic dystrophy type 1 (DM1) is a progressive neuromuscular disorder caused by an expanded CTG repeat tract in the DMPK gene, leading to RNA toxicity and widespread tissue dysfunction. Germline and somatic repeat instability are key contributors to disease onset and progression, yet the molecular mechanisms driving these processes remain poorly understood. To investigate drivers of germline and somatic instability, this project leverages a novel CRISPR-Cas9 knock-in allelic series of mice (Dmpk-KI) which contain 400-5000 CTG repeats in the endogenous mouse locus. These mice faithfully recapitulate human DM1 genetics and demonstrate many features consistent with DM1 symptoms in human patients. Leveraging modern-day long-read sequencing (LRS) technologies, we can systematically investigate factors influencing repeat instability. Specific Aim 1 will determine how parental sex and age impact germline instability, and also look at methylation signatures around the CTG repeat. Each of these focus areas has implications for congenital DM1, the most severe form of the disease. Specific Aim 2 will evaluate somatic expansion across multiple tissues, with a focus on R-loop formation as a potential driver of instability in post-mitotic cells. All work will be conducted in a highly collaborative environment, under the primary mentorship of Dr. Charles Thornton, a renowned expert in the field with over 30 years of working on DM1. By integrating cutting-edge sequencing and molecular biology techniques, this work will provide critical insights into mechanisms of DM1 and inform therapeutic strategies aimed at stabilizing expanded repeats. In parallel, this project serves as a career development platform, fostering expertise in animal models of neuromuscular disease, LRS, molecular genetics, and bioinformatics, all of which are critical skill gaps. This will be accomplished through formal and informal coursework at the University of Rochester, attending targeted symposia focused on LRS, and close relationships with my mentors and advisors. The proposed research and training will prepare me to lead larger studies on DM1 instability, and independently investigate mechanisms and treatments for other pediatric neuromuscular and repeat expansion disorders.