title: The subcellular localization of cyclin dependent kinase 2 determines the fate of mesangial cells: role in apoptosis and proliferation.
abstract: Apoptosis is closely linked to proliferation. In this study we showed that inducing apoptosis in mouse mesangial cells with ultraviolet (UV) irradiation was associated with increased cyclin A-cyclin dependent kinase (CDK) 2 activity. Inhibiting CDK2 activity with Roscovitine or dominant negative mutant reduced apoptosis. Because apoptosis typically begins in the cytoplasm, we tested the hypothesis that the subcellular localization of CDK2 determines the proliferative or apoptotic fate of the cell. Our results showed that cyclin A-CDK2 was nuclear in proliferating cells. However, inducing apoptosis in proliferating cells with UV irradiation was associated with a decrease in nuclear cyclin A and CDK2 protein levels. This coincided with an increase in protein and kinase activity for cyclin A-CDK2 in the cytoplasm. Translocation of cyclin A-CDK2 also occurred in p53-/- mesangial cells. Finally, we showed that caspase-3 activity was significantly reduced by inhibiting CDK2 activity with Roscovitine. In summary, our results show that apoptosis is associated with an increase in cytoplasmic cyclin A-CDK2 activity, which is p53 independent and upstream of caspase-3. We propose that the subcellular localization of CDK2 determines the proliferative or apoptotic fate of the cell.
authors.affiliation: Department of Medicine, Division of Nephrology, University of Washington School of Medicine, Seattle, Washington, WA 98195-6521, USA.
authors.forename: K
authors.initials: K
authors.lastname: Hiromura
authors.forename: J W
authors.initials: JW
authors.lastname: Pippin
authors.forename: M J
authors.initials: MJ
authors.lastname: Blonski
authors.forename: J M
authors.initials: JM
authors.lastname: Roberts
authors.forename: S J
authors.initials: SJ
authors.lastname: Shankland
mesh_terms: D000818:Animals; D017209:Apoptosis; D001692:Biological Transport; D042846:CDC2-CDC28 Kinases; D053148:Caspase 3; D020169:Caspases / Q000502:physiology; D002455:Cell Division; D002478:Cells, Cultured; D019925:Cyclin A / Q000502:physiology; D019927:Cyclin E / Q000502:physiology; D051357:Cyclin-Dependent Kinase 2; D018844:Cyclin-Dependent Kinases / Q000032:analysis / Q000502:physiology*; D003593:Cytoplasm / Q000201:enzymology; D005920:Glomerular Mesangium / Q000166:cytology* / Q000201:enzymology / Q000648:ultrastructure; D051379:Mice; D009685:Nuclear Envelope / Q000201:enzymology; D017346:Protein Serine-Threonine Kinases / Q000032:analysis / Q000502:physiology*; D016159:Tumor Suppressor Protein p53 / Q000502:physiology
chemical_list: D019925:Cyclin A; D019927:Cyclin E; D016159:Tumor Suppressor Protein p53; D017346:Protein Serine-Threonine Kinases; D042846:CDC2-CDC28 Kinases; C495893:Cdk2 protein, mouse; D051357:Cyclin-Dependent Kinase 2; D018844:Cyclin-Dependent Kinases; C505409:Casp3 protein, mouse; D053148:Caspase 3; D020169:Caspases