title: ASIC1a-specific modulation of acid-sensing ion channels in mouse cortical neurons by redox reagents.
abstract: Acid-sensing ion channel (ASIC)-1a, the major ASIC subunit with Ca2+ permeability, is highly expressed in the neurons of CNS. Activation of these channels with resultant intracellular Ca2+ accumulation plays a critical role in normal synaptic plasticity, learning/memory, and in acidosis-mediated glutamate receptor-independent neuronal injury. Here we demonstrate that the activities of ASICs in CNS neurons are tightly regulated by the redox state of the channels and that the modulation is ASIC1a subunit dependent. In cultured mouse cortical neurons, application of the reducing agents dramatically potentiated, whereas the oxidizing agents inhibited the ASIC currents. However, in neurons from the ASIC1 knock-out mice, neither oxidizing agents nor reducing reagents had any effect on the acid-activated current. In Chinese Hamster Ovary cells, redox-modifying agents only affected the current mediated by homomeric ASIC1a, but not homomeric ASIC1b, ASIC2a, or ASIC3. In current-clamp recordings and Ca(2+)-imaging experiments, the reducing agents increased but the oxidizing agents decreased acid-induced membrane depolarization and the intracellular Ca2+ accumulation. Site-directed mutagenesis studies identified involvement of cysteine 61 and lysine 133, located in the extracellular domain of the ASIC1a subunit, in the modulation of ASICs by oxidizing and reducing agents, respectively. Our results suggest that redox state of the ASIC1a subunit is an important factor in determining the overall physiological function and the pathological role of ASICs in the CNS.
authors.affiliation: Robert S. Dow Neurobiology Laboratories, Legacy Research, Portland, Oregon 97232, USA.
authors.forename: Xiang-Ping
authors.initials: XP
authors.lastname: Chu
authors.forename: Natasha
authors.initials: N
authors.lastname: Close
authors.forename: Julie A
authors.initials: JA
authors.lastname: Saugstad
authors.forename: Zhi-Gang
authors.initials: ZG
authors.lastname: Xiong
mesh_terms: D062565:Acid Sensing Ion Channels; D000595:Amino Acid Sequence / Q000502:physiology; D000818:Animals; D016466:CHO Cells; D002118:Calcium / Q000378:metabolism; D020013:Calcium Signaling / Q000187:drug effects / Q000502:physiology; D002478:Cells, Cultured; D002540:Cerebral Cortex / Q000187:drug effects / Q000378:metabolism*; D006224:Cricetinae; D003545:Cysteine / Q000737:chemistry; D045604:Extracellular Fluid / Q000737:chemistry; D008239:Lysine / Q000737:chemistry; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology; D008565:Membrane Proteins / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D018345:Mice, Knockout; D009419:Nerve Tissue Proteins / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D009474:Neurons / Q000187:drug effects / Q000378:metabolism*; D016877:Oxidants / Q000494:pharmacology; D010084:Oxidation-Reduction / Q000187:drug effects; D018408:Patch-Clamp Techniques; D017434:Protein Structure, Tertiary / Q000502:physiology; D019163:Reducing Agents / Q000494:pharmacology; D015222:Sodium Channels / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*
chemical_list: C568267:ASIC1 protein, mouse; D062565:Acid Sensing Ion Channels; D008565:Membrane Proteins; D009419:Nerve Tissue Proteins; D016877:Oxidants; D019163:Reducing Agents; D015222:Sodium Channels; D008239:Lysine; D003545:Cysteine; D002118:Calcium