Poster abstracts
Poster number 34 submitted by Jennifer Petrosino
METTL3 is an mRNA modifying methyltransferase that regulates hypertrophy in skeletal muscle
Jennifer M. Petrosino (Department of Physiology & Cell Biology, College of Medicine, Ohio State University, Columbus, OH; Biomedical Sciences Graduate Program, College of Medicine, Ohio State University, Columbus, OH.), Juan Barajas (Biomedical Sciences Graduate Program, College of Medicine, Ohio State University, Columbus, OH.), Lisa Dorn (Department of Physiology & Cell Biology, College of Medicine, Ohio State University, Columbus, OH; Biomedical Sciences Graduate Program, College of Medicine, Ohio State University, Columbus, OH.), Hui-Lung Sun (Department of Biochemistry and Molecular Biology and Institute for Biophysical Dynamics, Howard Hughes Medical Institute, University of Chicago, Chicago, IL.), Chuan He (Department of Biochemistry and Molecular Biology and Institute for Biophysical Dynamics, Howard Hughes Medical Institute, University of Chicago, Chicago, IL.), Federica Accornero (Department of Physiology & Cell Biology, College of Medicine, Ohio State University, Columbus, OH.)
Abstract:
Skeletal muscle is highly adaptable, and in response to anabolic stimuli and mechanical overload, increases in contractile protein synthesis promote increases in muscle size and mass. The majority of mechanisms known to regulate muscle hypertrophy focus on epigenetic modifications to DNA and post-translational modifications to proteins involved in hypertrophic signaling; however, it is unknown if mRNA modifications are required for skeletal muscle growth. METTL3 is an RNA methyltransferase responsible for catalyzing the deposition of N6-methyladenosine (m6A), the most abundant internal mRNA modification, marks on mammalian mRNA. Here, we found that METTL3 is induced, and the m6A modification is enriched, during hypertrophic muscle growth. Using MeRIP-Seq to map m6A-methylated RNAs in baseline and hypertrophic muscles, we identified that a specific subset of mRNAs, which code for contractile proteins required for increases in fiber cross-sectional area, are enriched in hypertrophy. To ascertain if METTL3 mediated m6A modifications were essential for hypertrophy, we generated an inducible myofiber-specific METTL3 knockout mouse (M3KO). Genetic ablation of METTL3 in mature fibers completely prevented synergistic ablation-induced hypertrophy without impacting baseline fiber size or pathology. Conversely, overexpression of METTL3 in WT and M3KO mice challenged with synergistic ablation surgeries was sufficient to rescue the blunted hypertrophic response of M3KO mice. Furthermore, METTL3 overexpression significantly increased the amount of hypertrophy and m6A levels in WT mice, demonstrating the necessity of METTL3 mediated RNA methylation for muscle growth. Together, our findings identify that the N6-adenosine methyltransferase METTL3 is required for, and promotes, the hypertrophic response of skeletal muscle.
Keywords: RNA Methylation, Skeletal Muscle, Hypertrophy