[Functional characterization of recombinant myostatin and its inhibitory role to chicken muscle development]

Myostatin is a recently discovered member of transforming growth factor beta (TGFbeta) superfamily and shares similar structure features with other members of TGFbeta superfamily. For a better understanding of molecular mechanism of myostatin function, the production of C-terminal truncated form of recombinant myostatin protein (rMSTN) in E. coli was previously reported. Herein, the functional role of the recombinant myostatin in regulating myogenesis in a chicken embryonic myoblasts (CEMs) system was determined. By using flow cytometric analysis, the myostatin was found to inhibit cell cycle transition from G1 to S phase and result in a cell cycle arrest at G1. In addition, myostatin blocked the multi-nucleus myotube formation and caused a decreased expression of the muscle cell differentiation markers (myogenin and MHC) in CEMs. In this study, a rabbit polyclonal antibody against myostatin was produced and high affinity and specificity of this anti-myostatin antibody to recombinant and endogenous myostatin were assayed by Western blot analysis. Further studies showed that the antibody could also recognize the tissue endogenous myostatin of human, mouse and rat. A specific 40 kD band was detected in chicken muscle, which suggested that chicken myostatin might have different splicing pattern. Immunofluorescence assay indicated that myostatin predominantly existed in the cytosol in C2C12 cells. Taken together, the results show that myostatin inhibits chicken muscle cells proliferation and differentiation and down-regulates expression of two differentiation marker gene in CEMs. Remarkably, production of functional recombinant myostatin protein and its specific antibody provides important reagents for unraveling molecular mechanisms underlying myostatin action during myogenesis.