GRSF1 Inhibits Myoblast Differentiation Through Repressing Mitochondrial ROS Production

Guanine-rich RNA sequence binding factor 1(GRSF1)is a member of the RNA-binding protein(RBP)family.GRSF1 exists in nucleus,cytoplasm and mitochondria and regulates RNA metabolism through RNA processing,transport and translation in the cytoplasm and mitochondria.However,its role in myogenesis has not been investigated.Here,we demonstrated that the expression of GRSF1 in mitochondria and its effect on mitochondrial function was negatively related to the differentiation of mouse skeletal muscle myoblast C2C12.Interference with GRSF1 in C2C12 cells promoted myogenic differentiation.In contrast,overexpression of GRSF1 inhibited cell differentiation.At the same time,changes in the expression level of GRSF1 did not affect the expression of the early differentiation marker MyoD or cell proliferation.Furdier studies indicated that GRSF1 regulates myogenic differentiation by directly targeting mitochondrial glutathione peroxidase 4(m-GPX4).m-GPX4 is a key regulator of cellular redox status and regulates mitochondrial ROS(mtROS)levels,which plays a very important role in myogenic differentiation.Interference with GRSF1 or m-GPX4 can led to an increase in mtROS levels and an acceleration of myogenic differentiation,whereas overexpression of GRSF1 or m-GPX4 reduced mtROS levels and inhibited myogenic differentiation.At the same time,when cell ROS was inhibited,the differentiation ability of myoblasts was inhibited,and the effect of promoting differentiation by GRSF1 or m-GPX4 was also inhibited.Our results revealed that the key function of GRSF1 during skeletal muscle formation was its regulation of muscle redox homeostasis.