title: Interaction of the c-Jun/JNK pathway and cyclin-dependent kinases in death of embryonic cortical neurons evoked by DNA damage.
abstract: DNA damage, an important initiator of neuronal death, has been implicated in numerous neurodegenerative conditions. We previously delineated several pathways that control embryonic cortical neuronal death evoked by the DNA-damaging agent, camptothecin. In this model, the tumor suppressor p53 and cyclin-dependent kinases (CDKs) are activated independently and cooperate to mediate the conserved death pathway. To further our understanding, we presently examined whether the c-Jun/JNK pathway modulates death and whether this pathway is regulated by CDKs, p53, and Bax. We show that c-Jun/JNK is activated following DNA damage. Moreover, the c-Jun pathway is one mediator of death, because expression of dominant negative c-Jun and cdc42, and JNK pathway inhibitors are neuroprotective. Although previous evidences indicate that JNK3 is required for neuronal death under certain conditions, we show that JNK3 deficiency only partially mediates c-Jun phosphorylation and its deficiency does not protect neurons from death. Interestingly, we provide evidence that CDK activity regulates c-Jun but does not affect upstream pathways that lead to JNK phosphorylation. Finally, c-Jun activation is independent of p53 and Bax. Accordingly, we propose that c-Jun is regulated by the JNK and CDK pathways and that both must be activated for efficient c-Jun activation to occur.
authors.affiliation: Neuroscience Research Institute, University of Ottawa, Ottawa, Ontario K1H 8M5, Canada.
authors.forename: Mohammad H
authors.initials: MH
authors.lastname: Ghahremani
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Keramaris
authors.forename: Tanaya
authors.initials: T
authors.lastname: Shree
authors.forename: Zhengui
authors.initials: Z
authors.lastname: Xia
authors.forename: Roger J
authors.initials: RJ
authors.lastname: Davis
authors.forename: Richard
authors.initials: R
authors.lastname: Flavell
authors.forename: Ruth S
authors.initials: RS
authors.lastname: Slack
authors.forename: David S
authors.initials: DS
authors.lastname: Park
mesh_terms: D000818:Animals; D001483:Base Sequence; D002166:Camptothecin / Q000494:pharmacology; D016923:Cell Death; D002540:Cerebral Cortex / Q000166:cytology / Q000196:embryology*; D018844:Cyclin-Dependent Kinases / Q000378:metabolism*; D004249:DNA Damage; D017931:DNA Primers; D018507:Gene Expression Regulation, Developmental / Q000187:drug effects; D048031:JNK Mitogen-Activated Protein Kinases; D051379:Mice; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D009474:Neurons / Q000166:cytology*; D010766:Phosphorylation; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D019253:Proto-Oncogene Proteins c-bcl-2; D016755:Proto-Oncogene Proteins c-jun / Q000378:metabolism*; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism; D051028:bcl-2-Associated X Protein
chemical_list: C494827:Bax protein, mouse; D017931:DNA Primers; D011518:Proto-Oncogene Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D016755:Proto-Oncogene Proteins c-jun; D016159:Tumor Suppressor Protein p53; D051028:bcl-2-Associated X Protein; D018844:Cyclin-Dependent Kinases; D048031:JNK Mitogen-Activated Protein Kinases; D020928:Mitogen-Activated Protein Kinases; D002166:Camptothecin