title: Loss of glutathione homeostasis associated with neuronal senescence facilitates TRPM2 channel activation in cultured hippocampal pyramidal neurons.
abstract: BACKGROUND
  Glutathione (GSH) plays an important role in neuronal oxidant defence. Depletion of cellular GSH is observed in neurodegenerative diseases and thereby contributes to the associated oxidative stress and Ca2+ dysregulation. Whether depletion of cellular GSH, associated with neuronal senescence, directly influences Ca2+ permeation pathways is not known. Transient receptor potential melastatin type 2 (TRPM2) is a Ca2+ permeable non-selective cation channel expressed in several cell types including hippocampal pyramidal neurons. Moreover, activation of TRPM2 during oxidative stress has been linked to cell death. Importantly, GSH has been reported to inhibit TRPM2 channels, suggesting they may directly contribute to Ca2+ dysregulation associated with neuronal senescence. Herein, we explore the relation between cellular GSH and TRPM2 channel activity in long-term cultures of hippocampal neurons.
  
  
  RESULTS
  In whole-cell voltage-clamp recordings, we observe that TRPM2 current density increases in cultured pyramidal neurons over time in vitro. The observed increase in current density was prevented by treatment with NAC, a precursor to GSH synthesis. Conversely, treatment of cultures maintained for 2 weeks in vitro with L-BSO, which depletes GSH by inhibiting its synthesis, augments TRPM2 currents. Additionally, we demonstrate that GSH inhibits TRPM2 currents through a thiol-independent mechanism, and produces a 3.5-fold shift in the dose-response curve generated by ADPR, the intracellular agonist for TRPM2.
  
  
  CONCLUSIONS
  These results indicate that GSH plays a physiologically relevant role in the regulation of TRPM2 currents in hippocampal pyramidal neurons. This interaction may play an important role in aging and neurological diseases associated with depletion of GSH.
authors.affiliation: Department of Anatomy and Cell Biology, University of Western Ontario, London, ON, N6A 5 K8, Canada.
authors.forename: Jillian C
authors.initials: JC
authors.lastname: Belrose
authors.forename: Yu-Feng
authors.initials: YF
authors.lastname: Xie
authors.forename: Lynn J
authors.initials: LJ
authors.lastname: Gierszewski
authors.forename: John F
authors.initials: JF
authors.lastname: MacDonald
authors.forename: Michael F
authors.initials: MF
authors.lastname: Jackson
mesh_terms: D000111:Acetylcysteine / Q000494:pharmacology; D000246:Adenosine Diphosphate Ribose / Q000494:pharmacology; D000818:Animals; D002478:Cells, Cultured; D016922:Cellular Senescence / Q000187:drug effects; D005786:Gene Expression Regulation / Q000187:drug effects; D005978:Glutathione / Q000378:metabolism* / Q000494:pharmacology; D057809:HEK293 Cells; D006706:Homeostasis / Q000187:drug effects; D006801:Humans; D015640:Ion Channel Gating / Q000187:drug effects; D051379:Mice; D009474:Neurons / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism; D017966:Pyramidal Cells / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D016194:Receptors, N-Methyl-D-Aspartate / Q000378:metabolism; D013438:Sulfhydryl Compounds / Q000378:metabolism; D050053:TRPM Cation Channels / Q000235:genetics / Q000378:metabolism*; D013997:Time Factors
chemical_list: D012333:RNA, Messenger; D016194:Receptors, N-Methyl-D-Aspartate; D013438:Sulfhydryl Compounds; D050053:TRPM Cation Channels; C544443:TRPM2 protein, mouse; D000246:Adenosine Diphosphate Ribose; D005978:Glutathione; D000111:Acetylcysteine