title: Survival response-linked Pyk2 activation during potassium depletion-induced apoptosis of cerebellar granule neurons.
abstract: Numerous extracellular stimuli trigger trans-autophosphorylation at Tyr402 of Pyk2, inducing its activation. Pyk2 is a key mediator of several signaling pathways and has been implicated in apoptosis induced by specific stress signals. We investigated whether Pyk2 participates in cerebellar granule neuron (CGN) apoptosis induced by the suppression of membrane depolarization. We demonstrate that shifting CGN cultures from 25 mM to 5 mM KCl-containing medium induces an early, transient 70% increase in phosphorylated Tyr402 and Tyr580 Pyk2 levels that is triggered by Ca(2+) released from intracellular stores and mediated by calmodulin (CaM). Overexpression of Pyk2 increases CGN survival after 24 h by 70% compared to the control, thus suggesting that Pyk2 is involved in an anti-apoptotic response to K+ lowering. Furthermore, we show that CGN grown in K25 medium exhibit detectable CaM-dependent Pyk2 activity. When silencing Pyk2 activity by expressing a dominant-negative form, only 40% of the transfected neurons were alive 24 h after transfection when compared to the control. Overall, the present findings demonstrate for the first time that Pyk2 is a critical mediator of CGN survival.
authors.affiliation: Institut National de la Santé et de la Recherche Médicale (INSERM), Laboratoire Neurodégénérescence et Plasticité, EMI108, France.
authors.forename: Flavie
authors.initials: F
authors.lastname: Strappazzon
authors.forename: Sakina
authors.initials: S
authors.lastname: Torch
authors.forename: Yaël
authors.initials: Y
authors.lastname: Trioulier
authors.forename: Béatrice
authors.initials: B
authors.lastname: Blot
authors.forename: Rémy
authors.initials: R
authors.lastname: Sadoul
authors.forename: Jean-Marc
authors.initials: JM
authors.lastname: Verna
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D000831:Animals, Newborn; D017209:Apoptosis / Q000187:drug effects / Q000502:physiology*; D020169:Caspases / Q000378:metabolism; D002470:Cell Survival / Q000187:drug effects; D002531:Cerebellum / Q000166:cytology*; D002614:Chelating Agents / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004347:Drug Interactions; D004533:Egtazic Acid / Q000031:analogs & derivatives / Q000494:pharmacology; D004789:Enzyme Activation / Q000187:drug effects; D051418:Focal Adhesion Kinase 2 / Q000378:metabolism*; D051379:Mice; D016296:Mutagenesis / Q000502:physiology; D009474:Neurons / Q000166:cytology / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism*; D011188:Potassium / Q000378:metabolism*; D011189:Potassium Chloride / Q000494:pharmacology; D012694:Serine / Q000378:metabolism; D013778:Tetrazolium Salts; D013844:Thiazoles; D013997:Time Factors; D014162:Transfection / Q000379:methods; D014443:Tyrosine / Q000378:metabolism
chemical_list: D002614:Chelating Agents; D013778:Tetrazolium Salts; D013844:Thiazoles; C070379:1,2-bis(2-aminophenoxy)ethane N,N,N',N'-tetraacetic acid acetoxymethyl ester; D014443:Tyrosine; D012694:Serine; D004533:Egtazic Acid; D011189:Potassium Chloride; D051418:Focal Adhesion Kinase 2; C496053:Ptk2b protein, mouse; D020169:Caspases; C022616:thiazolyl blue; D011188:Potassium