Abstract
Myostatin (MSTN) is transiently expressed in the developing skeletal muscle, and negatively regulates muscle growth. A loss of function mutation of the MSTN gene is known to result in excess muscle formation with elevated expression of Wnt4. To examine direct effect of Wnt4 on skeletal muscle formation, Wnt4 cDNA was misexpressed in the presumptive limb field of chick embryos using retrovirus vector. Significant increase in muscle mass was observed in the Wnt4-treated limb compared to the control. The area for fast-type myosin heavy chain-expressing cells showed a significant increase, suggesting the possible involvement of Wnt4 during fast-type muscle formation after MSTN knockout.
