Dietary methionine restriction: Effects on glucose tolerance, lipid content and micro-RNA composition in the muscle of rainbow trout

Lean muscle mass plays an important role in overall health, as altered skeletal muscle metabolism can impact both the incidence and prevention of conditions related to metabolic health. Intriguingly, dietary methionine restriction (MR) has been shown to ameliorate this phenotype over time potentially through mechanisms related to changes in myogenic precursor cell (MPC) differentiation status. Recently the role of micro-RNAs (miRs) in regulating the expression of muscle specific transcription factors myoD and myogenin as well as signaling molecules involved in skeletal muscle differentiation has been reported in vitro. We performed an 8 week feeding trial to determine if MR in vivo could alter miR abundance as well as change metabolic markers. Results show changes in muscle miR abundance for miR-133a at 4 weeks with no significant difference seen in miR-210 or miR-206. After 8 weeks of MR feeding fish demonstrated increased clearance of glucose, increased fat accumulation in the liver, and decreased fat accumulation in the muscle. These data demonstrate conservation of MR effects on fish metabolism, and suggest, for the first time, that miR-133a might play a role in tissue response to MR.