Transcriptomic Analysis of Single Isolated Myofibers Identifies miR-27a-3p and miR-142-3p as Regulators of Metabolism in Skeletal Muscle

Summary: Skeletal muscle is composed of different myofiber types that preferentially use glucose or lipids for ATP production. How fuel preference is regulated in these post-mitotic cells is largely unknown, making this issue a key question in the fields of muscle and whole-body metabolism. Here, we show that microRNAs (miRNAs) play a role in defining myofiber metabolic profiles. mRNA and miRNA signatures of all myofiber types obtained at the single-cell level unveiled fiber-specific regulatory networks and identified two master miRNAs that coordinately control myofiber fuel preference and mitochondrial morphology. Our work provides a complete and integrated mouse myofiber type-specific catalog of gene and miRNA expression and establishes miR-27a-3p and miR-142-3p as regulators of lipid use in skeletal muscle. : Chemello et al. characterize coding mRNAs and non-coding microRNAs expressed by myofibers of hindlimb mouse muscles, identifying complex interactions between these molecules that modulate mitochondrial functions and muscle metabolism. They demonstrate that specific short non-coding RNAs influence the contractile fiber composition of skeletal muscles by modulating muscle metabolism. Keywords: single myofiber, skeletal muscle metabolism, mitochondria, miRNAs, lipids