Cell cycle dependent distribution of proliferating cell nuclear antigen/cyclin and cdc2-kinase in mouse T-lymphoma cells.
The aim of the present study was to investigate bromodeoxyuridine (BrdU) uptake and coordinated distribution of proliferating cell nuclear antigen (PCNA) and p34-cdc2-kinase, two important proteins involved in cell cycle regulation and progression. Flow cytometric analysis of marker proteins in freshly plated mouse T-lymphoma cells (Yac-1 cells), using fluorescein isothiocyanate (FITC)-labeled specific antibodies, showed PCNA distributed throughout the cell cycle with increased intensity in S-phase. PCNA is essential for cells to cycle through S-phase and its synthesis is initiated during late G1-phase before incorporation of BrdU and remains high during active DNA replication. The intensity of PCNA fluorescence increases with the duration of incubation after plating. The cdc2-kinase was detectable in all phases of the cell cycle and the G2-M-phase appears to have the maximum concentrations. The cell cycle analysis of high dose colcemid (2 micrograms/ml) treated Yac-1 cells showed an aneuploid or hypodiploid population. Although the G2-M-phase seems to be the dominating population in aneuploid cells, the concentrations of cdc2-kinase were variable in this phase of cell cycle. The colcemid treatment at 25 ng/ml arrested 96% of cells in S-phase and G2-M-phase, but PCNA expression was evident in a portion of the cell population in G2-M-phase. Although cells blocked in M-phase seem to have high levels of cdc2-kinase, colcemid renders them inactive. From these data, it appears that the down regulation and/or inactivation of cdc2-kinase could be responsible for the colcemid arrest of cells in M-phase.
Brott
D A
DA
Department of Pathology and Experimental Toxicology, Parke-Davis Pharmaceutical Research, Warner-Lambert Company, Ann Arbor, Michigan 48106.
Alvey
J D
JD
Bleavins
M R
MR
de la Iglesia
F A
FA
Lalwani
N D
ND
D000818:Animals; D000951:Antigens, Neoplasm / Q000378:metabolism*; D001973:Bromodeoxyuridine / Q000378:metabolism; D016203:CDC2 Protein Kinase / Q000378:metabolism*; D002453:Cell Cycle / Q000502:physiology*; D002455:Cell Division / Q000502:physiology; D016399:Lymphoma, T-Cell / Q000201:enzymology / Q000378:metabolism* / Q000473:pathology; D051379:Mice; D008938:Mitosis / Q000502:physiology; D009687:Nuclear Proteins / Q000378:metabolism*; D018809:Proliferating Cell Nuclear Antigen; D014407:Tumor Cells, Cultured
D000951:Antigens, Neoplasm; D009687:Nuclear Proteins; D018809:Proliferating Cell Nuclear Antigen; D016203:CDC2 Protein Kinase; D001973:Bromodeoxyuridine