Okadaic acid overrides the S-phase check point and accelerates progression of G2-phase to induce premature mitosis in HeLa cells.
Okadaic acid has been shown to induce premature mitosis in HeLa cells belonging to both S-phase and G2-phase. The response is dependent on concentration and perhaps also on the differential susceptibility of cells to okadaic acid (OA). OA resembles caffeine in its ability to override the DNA-replication check point but differs in being capable of inducing premature mitosis in cells in G2-phase, thereby accelerating mitosis. Chromosomes from mitotic cells induced in G2-phase show a typical banding pattern similar to G-banding. From immunoblot experiments and survey of the relevant literature it has been argued that OA may modulate both a tyrosine kinase and a tyrosine phosphatase activity to override the S-phase checkpoint and accelerate the activation of MPF in cells in G2-phase, respectively.
Ghosh
S
S
Research Program IV, German Cancer Research Center, Heidelberg, Germany.
Schroeter
D
D
Paweletz
N
N
D002453:Cell Cycle / Q000187:drug effects; D002877:Chromosomes, Human / Q000502:physiology; D019926:Cyclin B; D056744:Cyclin B1; D016213:Cyclins / Q000032:analysis; D003513:Cycloheximide / Q000494:pharmacology; D004988:Ethers, Cyclic / Q000494:pharmacology*; D016195:G2 Phase / Q000187:drug effects*; D006367:HeLa Cells; D006801:Humans; D008938:Mitosis / Q000187:drug effects*; D019319:Okadaic Acid; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology; D016196:S Phase / Q000187:drug effects*
C534699:CCNB1 protein, human; D019926:Cyclin B; D056744:Cyclin B1; D016213:Cyclins; D004988:Ethers, Cyclic; D011500:Protein Synthesis Inhibitors; D019319:Okadaic Acid; D003513:Cycloheximide