Expression patterns of regulatory RNAs, including lncRNAs and tRNAs, during postnatal growth of normal and dystrophic (mdx) mouse muscles, and their response to taurine treatment

Post-natal skeletal muscle growth in mice is very rapid and involves complex changes in many cells types over the first 6 weeks of life. The acute onset of dystropathology also occurs around 3 weeks of age in the mdx mouse model of the human disease Duchenne Muscular Dystrophy (DMD). This study investigated (i) alterations in expression patterns of regulatory non-coding RNAs (ncRNAs) in vivo, including miRNAs, lncRNAs and tRNAs, during early growth of skeletal muscles in normal control C57Bl/10Scsn (C57) compared with dystrophic mdx mice from 2 to 6 Weeks of postnatal age, and revealed inherent differences in vivo for levels of 3 ncRNAs between C57 and mdx muscles before the onset of dystropathology. Since the amino acid taurine has many benefits and reduces disease severity in mdx mice, this study also (ii) determined the impact of taurine treatment on these expression patterns in mdx muscles at the onset of dystropathology (3 weeks) and after several bouts of myonecrosis and regeneration (6 weeks). Taurine treatment of mdx mice only altered ncRNA levels when administered from 18 days to 6 weeks of age, but a deficiency in tRNA levels was rectified earlier in mdx skeletal muscles treated from 14 days to 3 weeks. Myogenesis in tissue culture was also used to (iii) compare ncRNA expression patterns for both strains, and (iv) the response to taurine treatment. These analyses revealed intrinsic differences in ncRNA expression patterns during myogenesis between strains, as well as increased sensitivity of mdx ncRNA levels to taurine treatment.