[Construction of the skeletal muscle-specific TbetaR II knockout mice].

To generate the skeletal muscle-specific transforming growth factor beta receptor II (TbetaR II) gene knockout mice for the research on the function of the TbetaR II gene in skeletal muscles. TbetaR II (flox/flox) mice were generated using embryonic stem cell technology. The MCK-Cre mice were engineered containing Cre recombinase under the control of creatine kinase (MCK) muscle-specific promoter. TbetaR II (flox/flox) mice were crossed with MCK-Cre mice generating TbetaR II (flox/flox)/MCK-Cre double Tg mice. And then, TbetaR II (flox/wt) /MCK-Cre(+) double Tg mice were crossed with TbetaR II (flox/flox) mice to generate TbetaR II (flox/flox)/MCK- Cre(+) mice genetically ablating TbetaR II in cre-expressing skeletal muscle cells. As predicted, mice lacking TbetaR II by gene targeting in skeletal muscles were generated first in the world using Cre/loxP system. TbetaR II null mutant mice were viable, fertile and showed apparently normal development.