title: Cyclin e1 regulates Kv2.1 channel phosphorylation and localization in neuronal ischemia.
abstract: Kv2.1 is a major delayed rectifying K(+) channel normally localized to highly phosphorylated somatodendritic clusters in neurons. Excitatory stimuli induce calcineurin-dependent dephosphorylation and dispersal of Kv2.1 clusters, with a concomitant hyperpolarizing shift in the channel's activation kinetics. We showed previously that sublethal ischemia, which renders neurons transiently resistant to excitotoxic cell death, can also induce Zn(2+)-dependent changes in Kv2.1 localization and activation kinetics, suggesting that activity-dependent modifications of Kv2.1 may contribute to cellular adaptive responses to injury. Recently, cyclin-dependent kinase 5 (Cdk5) was shown to phosphorylate Kv2.1, with pharmacological Cdk5 inhibition being sufficient to decluster channels. In another study, cyclin E1 was found to restrict neuronal Cdk5 kinase activity. We show here that cyclin E1 regulates Kv2.1 cellular localization via inhibition of Cdk5 activity. Expression of cyclin E1 in human embryonic kidney cells prevents Cdk5-mediated phosphorylation of Kv2.1, and cyclin E1 overexpression in rat cortical neurons triggers dispersal of Kv2.1 channel clusters. Sublethal ischemia in neurons induces calcineurin-dependent upregulation of cyclin E1 protein expression and cyclin E1-dependent Kv2.1 channel declustering. Importantly, overexpression of cyclin E1 in neurons is sufficient to reduce excitotoxic cell death. These results support a novel role for neuronal cyclin E1 in regulating the phosphorylation status and localization of Kv2.1 channels, a likely component of signaling cascades leading to ischemic preconditioning.
authors.affiliation: Department of Neurobiology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15261.
authors.forename: Niyathi H
authors.initials: NH
authors.lastname: Shah
authors.forename: Anthony J
authors.initials: AJ
authors.lastname: Schulien
authors.forename: Katerina
authors.initials: K
authors.lastname: Clemens
authors.forename: Talia D
authors.initials: TD
authors.lastname: Aizenman
authors.forename: Thomas M
authors.initials: TM
authors.lastname: Hageman
authors.forename: Zachary P
authors.initials: ZP
authors.lastname: Wills
authors.forename: Elias
authors.initials: E
authors.lastname: Aizenman
mesh_terms: D000818:Animals; D002545:Brain Ischemia / Q000378:metabolism*; D016923:Cell Death / Q000502:physiology; D002478:Cells, Cultured; D051360:Cyclin-Dependent Kinase 5 / Q000378:metabolism; D016213:Cyclins / Q000378:metabolism*; D057809:HEK293 Cells; D006801:Humans; D019194:Ischemic Preconditioning; D009474:Neurons / Q000378:metabolism*; D010766:Phosphorylation; D010770:Phosphotransferases / Q000378:metabolism; D051381:Rats; D051669:Shab Potassium Channels / Q000378:metabolism*; D015398:Signal Transduction / Q000502:physiology
chemical_list: C492235:Cdk5r1 protein, rat; D016213:Cyclins; D051669:Shab Potassium Channels; C583044:cyclin E1, rat; D010770:Phosphotransferases; D051360:Cyclin-Dependent Kinase 5
keywords: Cdk5; Kv2.1; cyclin E1; excitotoxicity; ischemia; preconditioning