The distinct transcriptomes of slow and fast adult muscles are delineated by noncoding RNAs.

Adult muscles have a vast adaptation capacity, enabling function switches in response to altered conditions. During intensive physical activity, disease, or aging, adult skeletal muscles change and adjust their functions. The competence to adjust varies among muscles. Muscle-specific molecular mechanisms in healthy and normal conditions could designate changes in physiologic and pathologic conditions. We generated deep mRNA-sequencing data in adult fast and slow mouse muscles, and applying paired analysis, we identified that the muscle-specific signatures are composed of half of the muscle transcriptome. The fast muscles showed a more compact gene network that is concordant with homogenous myofiber typing, compared with the pattern in the slow muscle. The muscle-specific mRNA landscape did not correlate with alternative spicing, alternative polyadenylation, or the expression of muscle transcription factor gene networks. However, we found significant correlation between the differentially expressed noncoding RNAs, microRNAs (miRNAs) and long noncoding RNAs (lncRNAs) and their target genes. More than 25% of the genes expressed in a muscle-specific fashion were found to be targets of muscle-specific miRNAs and lncRNAs. We suggest that muscle-specific miRNAs and lncRNAs contribute to the establishment of muscle-specific transcriptomes in adult muscles.-Raz, V., Riaz, M., Tatum, Z., Kielbasa, S. M., 't Hoen, P. A. C. The distinct transcriptomes of slow and fast adult muscles are delineated by noncoding RNAs.