title: A differential role of macrophage TRPM2 channels in Ca²⁺ signaling and cell death in early responses to H₂O₂.
abstract: Reactive oxygen species such as H₂O₂ elevates the cytosolic Ca²⁺ concentration ([Ca²⁺]c) and causes cell death via poly(ADPR) polymerase (PARP) activation, which also represents the primary mechanism by which H₂O₂ activate the transient receptor potential melastatin-related 2 (TRPM2) channel as a Ca²⁺-permeable channel present in the plasma membrane or an intracellular Ca²⁺-release channel. The present study aimed to define the contribution and mechanisms of the TRPM2 channels in macrophage cells in mediating Ca²⁺ signaling and cell death during initial response to H₂O₂, using mouse peritoneal macrophage, RAW264.7, and differentiated THP-1 cells. H₂O₂ evoked robust increases in the [Ca²⁺]c, and such Ca²⁺ responses were significantly greater at body temperature than room temperature. H₂O₂-induced Ca²⁺ responses were strongly inhibited by pretreatment with PJ-34, a PARP inhibitor, and largely prevented by removal of extracellular Ca²⁺. Furthermore, H₂O₂-induced increases in the [Ca²⁺]c were completely abolished in macrophage cells isolated from trpm2-/- mice. H₂O₂ reduced macrophage cell viability in a duration- and concentration-dependent manner. H₂O₂-induced cell death was significantly attenuated by pretreatment with PJ-34 and TRPM2 channel deficiency but remained significant and persistent. Taken together, these results show that the TRPM2 channel in macrophage cells functions as a cell surface Ca²⁺-permeable channel that mediates Ca²⁺ influx and constitutes the principal Ca²⁺ signaling mechanism but has a limited, albeit significant, role in cell death during early exposure to H₂O₂.
authors.affiliation: School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds, United Kingdom.
authors.forename: Jie
authors.initials: J
authors.lastname: Zou
authors.forename: Justin F
authors.initials: JF
authors.lastname: Ainscough
authors.forename: Wei
authors.initials: W
authors.lastname: Yang
authors.forename: Alicia
authors.initials: A
authors.lastname: Sedo
authors.forename: Shu-Ping
authors.initials: SP
authors.lastname: Yu
authors.forename: Zhu-Zhong
authors.initials: ZZ
authors.lastname: Mei
authors.forename: Asipu
authors.initials: A
authors.lastname: Sivaprasadarao
authors.forename: David J
authors.initials: DJ
authors.lastname: Beech
authors.forename: Lin-Hua
authors.initials: LH
authors.lastname: Jiang
mesh_terms: D000200:Action Potentials / Q000187:drug effects / Q000502:physiology; D000818:Animals; D020013:Calcium Signaling / Q000502:physiology*; D016923:Cell Death; D002460:Cell Line; D005786:Gene Expression Regulation / Q000187:drug effects; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology*; D017737:Macrophages, Peritoneal / Q000187:drug effects* / Q000378:metabolism; D051379:Mice; D018345:Mice, Knockout; D009154:Mutation; D050053:TRPM Cation Channels / Q000235:genetics / Q000378:metabolism*
chemical_list: D050053:TRPM Cation Channels; C544443:TRPM2 protein, mouse; D006861:Hydrogen Peroxide
keywords: Ca2+ influx; ROS; TRPM2 channel; cell death; macrophage cells