FoxO1: a novel insight into its molecular mechanisms in the regulation of skeletal muscle differentiation and fiber type specification.

FoxO1, a member of the forkhead transcription factor forkhead box protein O (FoxO) family, is predominantly expressed in most muscle types. FoxO1 is a key regulator of muscle growth, metabolism, cell proliferation and differentiation. In the past two decades, many researches have indicated that FoxO1 is a negative regulator of skeletal muscle differentiation while contrasting opinions consider that FoxO1 is crucial for myoblast fusion. FoxO1 is expressed much higher in fast twitch fiber enriched muscles than in slow muscles and is also closely related to muscle fiber type specification. In this review, we summarize the molecular mechanisms of FoxO1 in the regulation of skeletal muscle differentiation and fiber type specification.