Reversal of terminal differentiation and control of DNA replication: cyclin A and Cdk2 specifically localize at subnuclear sites of DNA replication.
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.
Cardoso
M C
MC
Howard Hughes Medical Institute, Children's Hospital, Boston, Massachusetts 02115.
Leonhardt
H
H
Nadal-Ginard
B
B
D000818:Animals; D000952:Antigens, Polyomavirus Transforming / Q000378:metabolism; D001665:Binding Sites; D042846:CDC2-CDC28 Kinases; D002453:Cell Cycle / Q000502:physiology; D002454:Cell Differentiation; D002460:Cell Line; D002467:Cell Nucleus / Q000378:metabolism; D051357:Cyclin-Dependent Kinase 2; D018844:Cyclin-Dependent Kinases; D016213:Cyclins / Q000378:metabolism*; D004261:DNA Replication; D051379:Mice; D008957:Models, Genetic; D009132:Muscles / Q000166:cytology / Q000502:physiology; D011494:Protein Kinases / Q000378:metabolism*; D017346:Protein Serine-Threonine Kinases; D016196:S Phase
D000952:Antigens, Polyomavirus Transforming; D016213:Cyclins; D011494:Protein Kinases; D017346:Protein Serine-Threonine Kinases; D042846:CDC2-CDC28 Kinases; C495893:Cdk2 protein, mouse; D051357:Cyclin-Dependent Kinase 2; D018844:Cyclin-Dependent Kinases