title: Capacitative Ca2+ entry is involved in regulating soluble amyloid precursor protein (sAPPalpha) release mediated by muscarinic acetylcholine receptor activation in neuroblastoma SH-SY5Y cells.
abstract: Previous studies have demonstrated that stimulation of phospholipase C-linked G-protein-coupled receptors, including muscarinic M1 and M3 receptors, increases the release of the soluble form of amyloid precursor protein (sAPPalpha) by alpha-secretase cleavage. In this study, we examined the involvement of capacitative Ca2+ entry (CCE) in the regulation of muscarinic acetylcholine receptor (mAChR)-dependent sAPPalpha release in neuroblastoma SH-SY5Y cells expressing abundant M3 mAChRs. The sAPPalpha release stimulated by mAChR activation was abolished by EGTA, an extracellular Ca2+ chelator, which abolished mAChR-mediated Ca2+ influx without affecting Ca2+ mobilization from intracellular stores. However, mAChR-mediated sAPPalpha release was not inhibited by thapsigargin, which increases basal [Ca2+]i by depletion of Ca2+ from intracellular stores. While these results indicate that the mAChR-mediated increase in sAPPalpha release is regulated largely by Ca2+ influx rather than by Ca2+ mobilization from intracellular stores, we further investigated the Ca2+ entry mechanisms regulating this phenomenon. CCE inhibitors such as Gd3+, SKF96365, and 2-aminoethoxydiphenyl borane (2-APB), dose dependently reduced both Ca2+ influx and sAPPalpha release stimulated by mAChR activation, whereas inhibition of voltage-dependent Ca2+ channels, Na+/Ca2+ exchangers, or Na+-pumps was without effect. These results indicate that CCE plays an important role in the mAChR-mediated release of sAPPalpha.
authors.affiliation: Research Institute of Pharmaceutical Sciences, College of Pharmacy, Ewha Womans University, Seoul, Korea.
authors.forename: Jin Hyoung
authors.initials: JH
authors.lastname: Kim
authors.forename: Sinkyu
authors.initials: S
authors.lastname: Choi
authors.forename: Ji-Eun
authors.initials: JE
authors.lastname: Jung
authors.forename: Eun-Jihn
authors.initials: EJ
authors.lastname: Roh
authors.forename: Hwa-Jung
authors.initials: HJ
authors.lastname: Kim
mesh_terms: D000109:Acetylcholine / Q000378:metabolism; D016564:Amyloid beta-Protein Precursor / Q000378:metabolism*; D001921:Brain / Q000378:metabolism; D002118:Calcium / Q000378:metabolism*; D002121:Calcium Channel Blockers / Q000494:pharmacology; D015220:Calcium Channels / Q000187:drug effects / Q000378:metabolism*; D020013:Calcium Signaling / Q000502:physiology*; D045744:Cell Line, Tumor; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism; D002614:Chelating Agents / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006801:Humans; D007424:Intracellular Fluid / Q000187:drug effects / Q000378:metabolism; D009474:Neurons / Q000378:metabolism*; D010446:Peptide Fragments / Q000378:metabolism*; D011976:Receptors, Muscarinic / Q000378:metabolism*; D009435:Synaptic Transmission / Q000502:physiology; D050052:TRPC Cation Channels / Q000037:antagonists & inhibitors / Q000378:metabolism*
chemical_list: C545487:APP protein, human; D016564:Amyloid beta-Protein Precursor; D002121:Calcium Channel Blockers; D015220:Calcium Channels; D002614:Chelating Agents; D004791:Enzyme Inhibitors; D010446:Peptide Fragments; D011976:Receptors, Muscarinic; D050052:TRPC Cation Channels; D000109:Acetylcholine; D002118:Calcium