The intragenic microRNA in the dynamin 2 gene contributes to the pathology of X-linked centronuclear myopathy.

Mutations in the myotubularin 1 () gene can cause the fatal disease X-linked centronuclear myopathy (XLCNM), but the underlying mechanism is incompletely understood. In this report, using an disease model, we found that expression of the intragenic microRNA miR-199a-1 is up-regulated along with that of its host gene, dynamin 2 (), in XLCNM skeletal muscle. To assess the role of miR-199a-1 in XLCNM, we crossed with mice and found that the resultant double-knockout mice display markers of improved health, as evidenced by lifespans prolonged by 30% and improved muscle strength and histology. Mechanistic analyses showed that miR-199a-1 directly targets nonmuscle myosin IIA (NM IIA) expression and, hence, inhibits muscle postnatal development as well as muscle maturation. Further analysis revealed that increased expression and phosphorylation of signal transducer and activator of transcription 3 (STAT3) up-regulates expression in XLCNM muscle. Our results suggest that miR-199a-1 has a critical role in XLCNM pathology and imply that this microRNA could be targeted in therapies to manage XLCNM.