title: Role of methionine 35 in the intracellular Ca2+ homeostasis dysregulation and Ca2+-dependent apoptosis induced by amyloid beta-peptide in human neuroblastoma IMR32 cells.
abstract: Amyloid beta-peptide (Abeta) plays a fundamental role in the pathogenesis of Alzheimer's disease. We recently reported that the redox state of the methionine residue in position 35 of amyloid beta-peptide (Abeta) 1-42 (Met35) strongly affects the peptide's ability to trigger apoptosis and is thus a major determinant of its neurotoxicity. Dysregulation of intracellular Ca(2+) homeostasis resulting in the activation of pro-apoptotic pathways has been proposed as a mechanism underlying Abeta toxicity. Therefore, we investigated correlations between the Met35 redox state, Abeta toxicity, and altered intracellular Ca(2+) signaling in human neuroblastoma IMR32 cells. Cells incubated for 6-24 h with 10 microM Abeta1-42 exhibited significantly increased KCl-induced Ca(2+) transient amplitudes and resting free Ca(2+) concentrations. Nifedipine-sensitive Ca(2+) current densities and Ca(v)1 channel expression were markedly enhanced by Abeta1-42. None of these effects were observed when cells were exposed to Abeta containing oxidized Met35 (Abeta1-42(Met35-Ox)). Cell pre-treatment with the intracellular Ca(2+) chelator 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid acetoxymethyl ester (1 microM) or the Ca(v)1 channel blocker nifedipine (5 microM) significantly attenuated Abeta1-42-induced apoptosis but had no effect on Abeta1-42(Met35-Ox) toxicity. Collectively, these data suggest that reduced Met35 plays a critical role in Abeta1-42 toxicity by rendering the peptide capable of disrupting intracellular Ca(2+) homeostasis and thereby provoking apoptotic cell death.
authors.affiliation: Institute of Human Physiology, Medical School, Catholic University S Cuore, Rome, Italy.
authors.forename: Roberto
authors.initials: R
authors.lastname: Piacentini
authors.forename: Cristian
authors.initials: C
authors.lastname: Ripoli
authors.forename: Lucia
authors.initials: L
authors.lastname: Leone
authors.forename: Francesco
authors.initials: F
authors.lastname: Misiti
authors.forename: Maria Elisabetta
authors.initials: ME
authors.lastname: Clementi
authors.forename: Marcello
authors.initials: M
authors.lastname: D'Ascenzo
authors.forename: Bruno
authors.initials: B
authors.lastname: Giardina
authors.forename: Gian Battista
authors.initials: GB
authors.lastname: Azzena
authors.forename: Claudio
authors.initials: C
authors.lastname: Grassi
mesh_terms: D016229:Amyloid beta-Peptides / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects*; D002118:Calcium / Q000378:metabolism*; D002121:Calcium Channel Blockers / Q000494:pharmacology; D015220:Calcium Channels / Q000235:genetics / Q000378:metabolism; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects; D002614:Chelating Agents / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004533:Egtazic Acid / Q000031:analogs & derivatives / Q000494:pharmacology; D045604:Extracellular Fluid / Q000187:drug effects*; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D006706:Homeostasis / Q000187:drug effects*; D006801:Humans; D020287:In Situ Nick-End Labeling / Q000379:methods; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology / Q000528:radiation effects; D008715:Methionine / Q000378:metabolism*; D009447:Neuroblastoma / Q000378:metabolism; D009543:Nifedipine / Q000494:pharmacology; D010084:Oxidation-Reduction; D018408:Patch-Clamp Techniques; D010446:Peptide Fragments / Q000494:pharmacology*; D011189:Potassium Chloride / Q000494:pharmacology
chemical_list: D016229:Amyloid beta-Peptides; D002121:Calcium Channel Blockers; D015220:Calcium Channels; D002614:Chelating Agents; D010446:Peptide Fragments; C075222:amyloid beta-protein (1-42); C070379:1,2-bis(2-aminophenoxy)ethane N,N,N',N'-tetraacetic acid acetoxymethyl ester; D004533:Egtazic Acid; D011189:Potassium Chloride; D008715:Methionine; D009543:Nifedipine; D002118:Calcium