Poster abstracts
Poster number 67 submitted by Sarah Matatov
Human patient derived iPSCs as a system for studying cardiac dysfunctions in Myotonic Dystrophy type 1
Sarah N. Matatov (Department of Biochemistry University of Illinois, Urbana-Champaign, Illinois, USA), Chaitali Misra (Department of Biochemistry University of Illinois, Urbana-Champaign, Illinois, USA), Auinash Kalsotra (Department of Biochemistry, Cancer CenterIllinois, Carl R. Woese Institute of Genomic Biology, University of Illinois, Urbana-Champaign, Illinois, USA )
Abstract:
Myotonic Dystrophy type 1 (DM1), is the most prevalent form of adult-onset muscular dystrophy. DM1 is caused by a CTG trinucleotide repeat expansion in the 3’-UTR of the DMPK gene. Over 80% of DM1 patients experience heart dysfunctions making this the second leading cause of death for affected individuals. The CUG expanded repeat in RNA creates a toxic gain-of-function phenotype, which causes RNA aggregation into ribonuclear foci. These RNA foci sequester Muscleblind-like Splicing Regulators (MBNL) and cause over-expression of the CUGBP Elav-Like Family Member 1 (CELF1) family of splicing factors. Our lab recently demonstrated that aberrant expression of a non-muscle splice isoform of RNA-binding protein RBFOX2 triggers the characteristic cardiac conduction delay, atrioventricular heart blocks, and spontaneous arrhythmogenesis in DM1 hearts. To further study the mechanisms by which non-muscle RBFOX2 alters the electrophysiological properties and thereby induces cardiac arrhythmias in DM1, we generated a human cardiomyocyte cell culture model for DM1. We acquired induced pluripotent stem cells (iPSC) from a healthy donor, a patient with a mild case of DM1 (238 repeats), and another patient with severe case of DM1 (1150 repeats). We successfully established a robust protocol for differentiating these iPSC lines into beating cardiomyocytes with reliable morphologic, molecular, and functional features. Importantly, we demonstrate that the differentiated experimental cells faithfully recapitulate the classical characteristics of DM1, including ribonuclear foci formation, MBNL sequestration, misregulation of alternative splicing, cardiac conduction delay, and contractility defects. Using these human patient-derived cardiac culture systems, we are now investigating the mechanistic and functional roles of specific RNA binding proteins in DM1 cardiac pathogenesis.
Keywords: Muscular Dystrophy, Cardiac Dysfunction, iPSCs