Olson E N, Caldwell K L, Gordon J I, Glaser L
J Biol Chem. 1983 Feb 25;258(4):2644-52.
The intracellular mechanisms involved in the regulation of creatine phosphokinase expression in the BC3H1 muscle-like cell line have been examined under conditions of enzyme induction and repression. In the presence of low serum concentrations, BC3H1 cells cease to grow and synthesize high levels of creatine phosphokinase. When differentiated BC3H1 cultures are exposed to media containing high serum concentrations, cell division is reinitiated and further induction of creatine phosphokinase is inhibited. Accumulation of creatine phosphokinase-mRNA appears to be intimately coupled to the state of growth of BC3H1 cells. Log phase cells do not contain detectable levels of translatable creatine phosphokinase-mRNA; however, following cessation of growth, creatine phosphokinase-mRNA accumulates in approximate proportion to the increase in creatine phosphokinase activity. Reinitiation of cell division in quiescent differentiated cultures results in the arrest of further accumulation of creatine phosphokinase-mRNA but does not inhibit the translation of pre-existing creatine phosphokinase-mRNA. Under conditions of enzyme repression, however, the newly synthesized creatine phosphokinase appears to be enzymatically inactive. These results indicate that the expression of the muscle phenotype in BC3H1 cells is regulated by components present in serum and that myogenic differentiation is at least partially reversible following re-entry of quiescent cells into the cell cycle.
在酶诱导和抑制的条件下，研究了BC3H1肌肉样细胞系中参与肌酸磷酸激酶表达调控的细胞内机制。在低血清浓度存在的情况下，BC3H1细胞停止生长并合成高水平的肌酸磷酸激酶。当分化的BC3H1培养物暴露于含有高血清浓度的培养基中时，细胞分裂重新启动，肌酸磷酸激酶的进一步诱导受到抑制。肌酸磷酸激酶mRNA的积累似乎与BC3H1细胞的生长状态密切相关。对数期细胞不含可检测水平的可翻译肌酸磷酸激酶mRNA；然而，在生长停止后，肌酸磷酸激酶mRNA的积累与肌酸磷酸激酶活性的增加大致成比例。静止分化培养物中细胞分裂的重新启动导致肌酸磷酸激酶mRNA的进一步积累停止，但不抑制预先存在的肌酸磷酸激酶mRNA的翻译。然而，在酶抑制的条件下，新合成的肌酸磷酸激酶似乎没有酶活性。这些结果表明，BC3H1细胞中肌肉表型的表达受血清中存在的成分调节，并且静止细胞重新进入细胞周期后，肌源性分化至少部分是可逆的。
