Training-induced plasma miR-29a-3p is secreted by skeletal muscle and contributes to metabolic adaptations to resistance exercise in mice

OBJECTIVE: The adaptive response to different models of regular exercise involves complex tissue crosstalk. Our aim was to explore the involvement of extracellular vesicle (EV) microRNAs (miRNAs) in this process, the secretory role of skeletal muscle and its functional metabolic interaction with the liver. METHODS: Plasma EV miRNAs obtained from mice after 4-weeks of endurance or resistance training were sequenced. Subsequent experiments using trained genetically modified mouse models and in vitro approaches involving knock-down and electrostimulated cells, were conducted. RESULTS: Resistance training increased the expression of a group of 11 miRNAs functionally divided into two clusters. Among them, miR-29a-3p emerges as a molecular mediator released in EVs by skeletal muscle, with a relevant role in adaptation to endurance training, by contributing to modulate the expression and secretion of other miRNAs associated with training and regulating processes related to substrate availability, transport, and metabolic use in skeletal muscle and liver. CONCLUSIONS: Our study suggests that miR-29a-3p is a training-induced molecular mediator in the response and adaptation to resistance training, possibly due to its regulatory role in energy metabolism in skeletal muscle in response to exercise.