By Arshpreet Brar and Delaney Humphrey

Faculty Mentor: Dr. Ginny Morriss

Abstract

Myotonic Dystrophy type 1 (DM1) has variable symptoms like myotonia, skeletal muscle weakness and wasting, irregular cardiac induction, and cognitive defects. DM1 is caused due to CTG repeat expansion in the 3′ untranslated region of the Dystrophia Myotonica Protein Kinase (DMPK) gene. The mutant DMPK transcripts are stabilized by RBPs such as Muscle blind-like protein 1 (MBNL1), which prevent DMPK mRNA nuclear export and increase retention in the nucleus into discrete foci. MBNL1 sequestration is responsible for many pathogenic effects due to the misregulated alternative splicing of RNA transcripts. A few examples of misregulated target genes are CACNA1S, CLCN1, NFIX, and ATP2A1, which produce aberrant proteins that lead to muscle weakness and myotonia, contributing to the complexity of the disease. We used DNAymes to cleave the CTG repeats, and we will determine if MBNL1 activity is restored in skeletal muscle cells of DM1 patients. We harvested cells on day seven of differentiation. After harvesting the cells, we isolated RNA, and we will perform RT-qPCR. A factorial ANOVA test will be used to calculate the statistical significance of the obtained data using genotype and treatment as independent variables. Bar graphs will be created to represent the expression fold change compared to the control cells. The results will help us determine if DNAzyme treatment restored MBNL1 function in skeletal muscle cells of DM1 patients.