TGFbeta3 is expressed in differentiating muscle of the embryonic mouse tongue

The purpose of the present study was to elucidate the involvement of transforming growth factor betas (TGFbetas) in the differentiation of tongue striated muscles by analyzing the expression of TGFbetas, their receptors and factors of TGFbeta signal transduction in the mouse tongue between embryonic days 11 (E11) and E15. The expression levels of TGFbeta3 mRNA and protein were much higher than those of TGFbeta1 and TGFbeta2, and the immunolocalization of TGFbeta3 was more consistent with the differentiating muscle cells in comparison with those of TGFbeta1 and 2 between E12 and E15. TGFbetaRI and II were localized to the differentiating muscle cells between E11 and E15. Phosphorylated-smad2/3 was localized to the nucleus of muscle cells which just began to differentiate. These results suggest that the signal of TGFbeta3, but not that of beta1 or beta2, may be involved in the early stages (particularly the beginning) of differentiation of mouse tongue muscle cells through TGFbetaRI, TGFbetaRII, and smad2/3.