Wang J, Nadal-Ginard B
Department of Cardiology, Children's Hospital, Boston, Massachusetts 02115.
Biochem Biophys Res Commun. 1995 Jan 5;206(1):82-8. doi: 10.1006/bbrc.1995.1012.
Little is known about the expression of cell cycle regulatory genes upon terminal differentiation of skeletal muscle cells. In this report, we demonstrate that the expressions of cyclin A, cyclin D1 and p34cdc2 are downregulated upon C2C12 myocytes differentiation and are not inducible in differentiated myotubes. SV40 large T antigen can induce cell cycle entry of myotubes through its induction of these genes' expressions and pRB phosphorylation as well as its suppression of Rb expression. These results provide the first direct evidence that the irreversible downregulation of cyclins and cyclin-dependent kinases is one mechanism for the permanent cell cycle withdrawal of myotubes.
关于骨骼肌细胞终末分化过程中细胞周期调控基因的表达，人们了解甚少。在本报告中，我们证明，C2C12肌细胞分化时，细胞周期蛋白A、细胞周期蛋白D1和p34cdc2的表达下调，且在分化的肌管中无法被诱导。SV40大T抗原可通过诱导这些基因的表达、pRB磷酸化以及抑制Rb表达，促使肌管进入细胞周期。这些结果首次直接证明，细胞周期蛋白和细胞周期蛋白依赖性激酶的不可逆下调是肌管永久性退出细胞周期的一种机制。
