Transthyretin Is a Key Regulator of Myoblast Differentiation

Transthyretin (TTR) is a known carrier protein for thyroxine (T(4)) and retinol-binding protein in the blood that is primarily synthesized in the liver and choroid plexus of the brain. Herein, we report that the TTR gene is expressed in skeletal muscle tissue and up-regulated during myotube formation in C2C12 cells. TTR silencing (TTR(kd)) significantly reduced myogenin expression and myotube formation, whereas myogenin silencing (MYOG(kd)) did not have any effect on TTR gene expression. Both TTR(kd) and MYOG(kd) led to a decrease in calcium channel related genes including Cav1.1, STIM1 and Orai1. A significant decrease in intracellular T(4) uptake during myogenesis was observed in TTR(kd) cells. Taken together, the results of this study suggest that TTR initiates myoblast differentiation via affecting expression of the genes involved during early stage of myogenesis and the genes related to calcium channel.