Cardoso M C, Leonhardt H, Nadal-Ginard B
Howard Hughes Medical Institute, Children's Hospital, Boston, Massachusetts 02115.
Cell. 1993 Sep 24;74(6):979-92. doi: 10.1016/0092-8674(93)90721-2.
DNA replication in mammalian cells occurs in discrete nuclear foci. Here we show that terminally differentiated myotubes can be induced to reenter S phase and show the same pattern of replication foci as cycling cells. We used this cellular system to analyze the interaction of cell cycle proteins with these foci in vivo. Cyclin A and cdk2, but not cyclin B1 and cdc2, were specifically localized at nuclear replication foci, just like the replication protein proliferating cell nuclear antigen. A potential target of cyclin A and cdk2 is the 34 kd subunit of replication protein A (RPA34). In contrast with the 70 kd subunit, which localizes to the foci, RPA34 was not detected at these replication sites, which may reflect a transient interaction. The specific localization of cyclin A and cdk2 at nuclear replication foci provides a direct link between cell cycle regulation and DNA replication.
哺乳动物细胞中的DNA复制发生在离散的核灶中。我们在此表明，终末分化的肌管可被诱导重新进入S期，并呈现出与循环细胞相同的复制灶模式。我们利用这个细胞系统来分析细胞周期蛋白在体内与这些灶的相互作用。细胞周期蛋白A和细胞周期蛋白依赖性激酶2（cdk2），而不是细胞周期蛋白B1和细胞分裂周期蛋白2（cdc2），特异性地定位于核复制灶，就像复制蛋白增殖细胞核抗原一样。细胞周期蛋白A和cdk2的一个潜在靶标是复制蛋白A（RPA）的34kd亚基（RPA34）。与定位于灶的70kd亚基不同，在这些复制位点未检测到RPA34，这可能反映了一种瞬时相互作用。细胞周期蛋白A和cdk2在核复制灶的特异性定位提供了细胞周期调控与DNA复制之间的直接联系。
