title: Enhanced activation of Ca2+/calmodulin-dependent protein kinase II upon downregulation of cyclin-dependent kinase 5-p35.
abstract: Cyclin-dependent kinase 5 (Cdk5)-p35 is downregulated in cultured neurons by N-methyl-D-aspartate (NMDA) via the proteasomal degradation of p35. However, it is not known where in neurons this downregulation occurs or the physiologic meaning of the reaction. We show the enrichment of Cdk5 and p35 in the postsynaptic density and the NMDA-induced degradation of postsynaptic p35 using brain slices and cultured neurons. To evaluate the role of this downregulation, we examined the relationship between Ca(2+)/calmodulin-dependent protein kinase II (CaMKII) activation and Cdk5 downregulation, as events downstream from NMDA stimulation. Glutamate or NMDA stimulation induced CaMKII autophosphorylation over a time course that mirrored the time course of p35 degradation. To simulate the downregulation of postsynaptic Cdk5 in invitro experiments, we used the Cdk5 inhibitor roscovitine. The inhibition of Cdk5 activity by roscovitine enhanced CaMKII autophosphorylation and activation in cultured neurons, and in an isolated postsynaptic-density-enriched fraction. These results suggest that Cdk5 activity suppresses CaMKII activation, and that the downregulation of Cdk5 activity after treatment withNMDA facilitates CaMKII activation, leading to the easier induction of long-term potentiation.
authors.affiliation: Department of Biological Sciences, Graduate School of Science, Tokyo Metropolitan University, Hachiohji, Tokyo, Japan. hosokawa-tomohisa@ed.tmu.ac.jp
authors.forename: Tomohisa
authors.initials: T
authors.lastname: Hosokawa
authors.forename: Taro
authors.initials: T
authors.lastname: Saito
authors.forename: Akiko
authors.initials: A
authors.lastname: Asada
authors.forename: Toshio
authors.initials: T
authors.lastname: Ohshima
authors.forename: Makoto
authors.initials: M
authors.lastname: Itakura
authors.forename: Masami
authors.initials: M
authors.lastname: Takahashi
authors.forename: Kohji
authors.initials: K
authors.lastname: Fukunaga
authors.forename: Shin-Ichi
authors.initials: S
authors.lastname: Hisanaga
mesh_terms: D000818:Animals; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000378:metabolism*; D002478:Cells, Cultured; D002540:Cerebral Cortex / Q000166:cytology; D051360:Cyclin-Dependent Kinase 5 / Q000235:genetics / Q000378:metabolism*; D015536:Down-Regulation / Q000187:drug effects / Q000502:physiology*; D004622:Embryo, Mammalian; D004789:Enzyme Activation / Q000187:drug effects / Q000502:physiology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D018690:Excitatory Amino Acid Agonists / Q000494:pharmacology; D005455:Fluorescent Antibody Technique / Q000379:methods; D018698:Glutamic Acid / Q000494:pharmacology; D047468:Immunoprecipitation / Q000379:methods; D066298:In Vitro Techniques; D016202:N-Methylaspartate / Q000494:pharmacology; D009474:Neurons / Q000187:drug effects / Q000378:metabolism*; D010766:Phosphorylation / Q000187:drug effects; D010770:Phosphotransferases / Q000378:metabolism*; D011494:Protein Kinases / Q000378:metabolism; D011687:Purines / Q000494:pharmacology; D051381:Rats; D000077546:Roscovitine
chemical_list: C492235:Cdk5r1 protein, rat; D004791:Enzyme Inhibitors; D018690:Excitatory Amino Acid Agonists; D011687:Purines; D000077546:Roscovitine; D018698:Glutamic Acid; D016202:N-Methylaspartate; D010770:Phosphotransferases; D011494:Protein Kinases; C102333:histone H1 kinase; D051360:Cyclin-Dependent Kinase 5; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2; D017871:Calcium-Calmodulin-Dependent Protein Kinases