title: Molecular mechanism of constitutive endocytosis of Acid-sensing ion channel 1a and its protective function in acidosis-induced neuronal death.
abstract: Acid-sensing ion channels (ASICs) are proton-gated cation channels widely expressed in the peripheral and CNSs, which critically contribute to a variety of pathophysiological conditions that involve tissue acidosis, such as ischemic stroke and epileptic seizures. However, the trafficking mechanisms of ASICs and the related proteins remain largely unknown. Here, we demonstrate that ASIC1a, the main ASIC subunit in the brain, undergoes constitutive endocytosis in a clathrin- and dynamin-dependent manner in both mouse cortical neurons and heterologous cell cultures. The endocytosis of ASIC1a was inhibited by either the small molecular inhibitor tyrphostin A23 or knockdown of the core subunit of adaptor protein 2 (AP2) μ2 using RNA interference, supporting a clathrin-dependent endocytosis of ASIC1a. In addition, the internalization of ASIC1a was blocked by dominant-negative dynamin1 mutation K44A and the small molecular inhibitor dynasore, suggesting that it is also dynamin-dependent. We show that the membrane-proximal residues (465)LCRRG(469) at the cytoplasmic C terminus of ASIC1a are critical for interaction with the endogenous adaptor protein complex and inhibition of ASIC1a internalization strongly exacerbated acidosis-induced death of cortical neurons from wild-type but not ASIC1a knock-out mice. Together, these results reveal the molecular mechanism of ASIC1a internalization and suggest the importance of endocytic pathway in functional regulation of ASIC1a channels as well as neuronal damages mediated by these channels during neurodegeneration.
authors.affiliation: Institute of Neuroscience and State Key Laboratory of Neuroscience, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China.
authors.forename: Wei-Zheng
authors.initials: WZ
authors.lastname: Zeng
authors.forename: Di-Shi
authors.initials: DS
authors.lastname: Liu
authors.forename: Bo
authors.initials: B
authors.lastname: Duan
authors.forename: Xing-Lei
authors.initials: XL
authors.lastname: Song
authors.forename: Xiang
authors.initials: X
authors.lastname: Wang
authors.forename: Dong
authors.initials: D
authors.lastname: Wei
authors.forename: Wen
authors.initials: W
authors.lastname: Jiang
authors.forename: Michael X
authors.initials: MX
authors.lastname: Zhu
authors.forename: Yong
authors.initials: Y
authors.lastname: Li
authors.forename: Tian-Le
authors.initials: TL
authors.lastname: Xu
mesh_terms: D062565:Acid Sensing Ion Channels / Q000737:chemistry / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D000138:Acidosis / Q000473:pathology*; D033962:Adaptor Protein Complex 2 / Q000378:metabolism; D000818:Animals; D019921:Biotinylation; D016923:Cell Death / Q000235:genetics; D002478:Cells, Cultured; D002540:Cerebral Cortex / Q000166:cytology; D002966:Clathrin / Q000378:metabolism; D006224:Cricetinae; D034281:Dynamins / Q000378:metabolism; D004558:Electric Stimulation; D004622:Embryo, Mammalian; D004705:Endocytosis / Q000235:genetics*; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D047468:Immunoprecipitation; D051379:Mice; D018345:Mice, Knockout; D009474:Neurons / Q000378:metabolism* / Q000502:physiology; D018408:Patch-Clamp Techniques; D010455:Peptides / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D013111:Spider Venoms / Q000494:pharmacology; D013347:Subcellular Fractions / Q000378:metabolism; D014162:Transfection; D020032:Tyrphostins / Q000378:metabolism
chemical_list: C568267:ASIC1 protein, mouse; D062565:Acid Sensing Ion Channels; D033962:Adaptor Protein Complex 2; D002966:Clathrin; C413209:PcTX1 protein, Psalmopoeus cambridgei; D010455:Peptides; D013111:Spider Venoms; D020032:Tyrphostins; D049452:Green Fluorescent Proteins; D034281:Dynamins; C060641:tyrphostin A23