title: Inhibition of protein kinase B activity induces cell cycle arrest and apoptosis during early G₁ phase in CHO cells.
abstract: Inhibition of PKB (protein kinase B) activity using a highly selective PKB inhibitor resulted in inhibition of cell cycle progression only if cells were in early G1 phase at the time of addition of the inhibitor, as demonstrated by time-lapse cinematography. Addition of the inhibitor during mitosis up to 2 h after mitosis resulted in arrest of the cells in early G1 phase, as deduced from the expression of cyclins D and A and incorporation of thymidine. After 24 h of cell cycle arrest, cells expressed the cleaved caspase-3, a central mediator of apoptosis. These results demonstrate that PKB activity in early G1 phase is required to prevent the induction of apoptosis. Using antibodies, it was demonstrated that active PKB translocates to the nucleus during early G1 phase, while an even distribution of PKB was observed through cytoplasm and nucleus during the end of G1 phase.
authors.affiliation: Cellular Dynamics, Institute of Biomembranes, Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands.
authors.forename: Angélique
authors.initials: A
authors.lastname: van Opstal
authors.forename: José
authors.initials: J
authors.lastname: Bijvelt
authors.forename: Elly
authors.initials: E
authors.lastname: van Donselaar
authors.forename: Bruno M
authors.initials: BM
authors.lastname: Humbel
authors.forename: Johannes
authors.initials: J
authors.lastname: Boonstra
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D016466:CHO Cells; D053148:Caspase 3 / Q000235:genetics / Q000378:metabolism*; D002747:Chlorpropamide / Q000031:analogs & derivatives* / Q000494:pharmacology; D006224:Cricetinae; D018844:Cyclin-Dependent Kinases / Q000235:genetics / Q000378:metabolism; D016213:Cyclins / Q000235:genetics / Q000378:metabolism; D059585:G1 Phase Cell Cycle Checkpoints / Q000187:drug effects*; D005786:Gene Expression Regulation / Q000187:drug effects; D008938:Mitosis / Q000187:drug effects; D047428:Protein Kinase Inhibitors / Q000494:pharmacology*; D021381:Protein Transport / Q000187:drug effects; D051057:Proto-Oncogene Proteins c-akt / Q000037:antagonists & inhibitors* / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D013936:Thymidine / Q000378:metabolism; D059008:Time-Lapse Imaging; D000096926:Benzenesulfonamides
chemical_list: D053148:Caspase 3; D002747:Chlorpropamide; D018844:Cyclin-Dependent Kinases; D016213:Cyclins; D047428:Protein Kinase Inhibitors; D051057:Proto-Oncogene Proteins c-akt; D013936:Thymidine; C111224:API 2; D000096926:Benzenesulfonamides