mt-Ty 5´tiRNA regulates skeletal muscle cell proliferation and differentiation

Understanding the molecular mechanisms underlying the regulation of gene expression during skeletal muscle cell proliferation and differentiation is critical to the development of novel therapeutic targets to treat muscle disorders. In this study, we report the identification and characterization of mt-Ty 5’tiRNAs, tRNA-derived fragments (tiRNAs) we identified in skeletal muscle. mt-Ty 5’tiRNAs are found in the nucleus and mitochondria of skeletal muscle cells and its expression is induced by angiogenin. Gapmer-mediated inhibition of tiRNAs in skeletal muscle C2C12 myoblasts resulted in mitochondrial fragmentation. We also observed a decrease in cell proliferation and myogenic differentiation upon mt-Ty 5’tiRNA inhibition; consistent with this observation, RNA-seq and transcriptome analyses revealed that skeletal muscle cell differentiation and cell proliferation pathways were also downregulated. Conversely, overexpression of mt-Ty 5’tiRNAs in C2C12 cells led to a reversal of the transcriptional trends noted for these pathway genes. These data reveal mt-Ty 5’tiRNAs as a skeletal muscle enriched tiRNA that plays important roles in myoblast proliferation and differentiation. Our study also highlights the potential for the development of tiRNAs as novel therapeutic targets for muscle related diseases Comparative transcripts profiling analysis of RNA-seq data for mt-Ty 5’tiRNAs gapmer, and control with two biological replicates ; the mt-Ty 5’tiRNAs overexpression and control with four biological replicates.