FHL3 gene regulates bovine skeletal muscle cell growth through the PI3K/Akt/mTOR signaling pathway

Beef quality is a critical factor in evaluating the effectiveness of beef cattle production. Fiber types play key roles in determining muscle growth and meat quality characteristics. FHL3 is de novo expressed in skeletal muscle and is responsible for MyHC isoform expression in C2C12 cells. Nevertheless, the precise function of this factor in regulating the proliferation, differentiation, and fiber type of bovine skeletal muscle cells (BSMCs) have yet to be identified. This study aimed to investigate the impact of the FHL3 on BSMCs proliferation, differentiation, and muscle fiber types. The results revealed that the FHL3 promoted BSMCs proliferation, inhibited differentiation, increased type II muscle fiber expression, and decreased type I muscle fiber expression. Meanwhile, the FHL3 promoted the expression and phosphorylation levels of PI3K, Akt, and mTOR in the PI3K/Akt/mTOR signaling pathway, and inhibited the expression and phosphorylation levels of PI3K, Akt, and mTOR after treatment with the pathway inhibitor LY294002, furthermore, it promoted differentiation and inhibited proliferation of BSMCs, while promoting the expression of type II muscle fibers and inhibiting the expression of type I muscle fibers. The results suggest that the FHL3 has an effect on promoting the proliferation and inhibiting the differentiation of BSMCs through the PI3K/Akt/mTOR signaling pathway, but the effect of the FHL3 on myofiber type conversion is not regulated by this pathway. The objective of this study is to enhance our understanding of the molecular function of FHL3 in the development of BSMCs.