{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,24]],"date-time":"2026-09-24T01:34:08Z","timestamp":1790213648652,"version":"4.1.0"},"reference-count":39,"publisher":"Wiley","issue":"24","license":[{"start":{"date-parts":[[2023,11,8]],"date-time":"2023-11-08T00:00:00Z","timestamp":1699401600000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/onlinelibrary.wiley.com\/termsAndConditions#vor"}],"funder":[{"DOI":"10.13039\/501100002426","name":"Fondazione Telethon","doi-asserted-by":"publisher","award":["GMR22T1029"],"award-info":[{"award-number":["GMR22T1029"]}],"id":[{"id":"10.13039\/501100002426","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":["physoc.onlinelibrary.wiley.com"],"crossmark-restriction":true},"short-container-title":["The Journal of Physiology"],"published-print":{"date-parts":[[2023,12]]},"abstract":"<jats:sec><jats:title>Abstract<\/jats:title><jats:p>ClC\u20106 and ClC\u20107 are closely related, intracellular Cl<jats:sup>\u2212<\/jats:sup>\/H<jats:sup>+<\/jats:sup> antiporters belonging to the CLC family of channels and transporters. They localize to acidic late endosomes and lysosomes and probably function in ionic homeostasis of these contiguous compartments. ClC\u20107 transport function requires association with the accessory protein Ostm1, whereas ClC\u20106 transport does not. To elucidate their roles in endo\u2010lysosomes, we measured Cl<jats:sup>\u2212<\/jats:sup>\u2010 and pH\u2010dependences of over\u2010expressed wild\u2010type ClC\u20106 and ClC\u20107, as well as disease\u2010associated mutants, using high\u2010resolution recording protocols. Lowering extracellular Cl<jats:sup>\u2212<\/jats:sup> (corresponding to luminal Cl<jats:sup>\u2212<\/jats:sup> in endo\u2010lysosomes) reduced ClC\u20106 currents, whereas it increased transport activity of ClC\u20107\/Ostm1. Low extracellular Cl<jats:sup>\u2212<\/jats:sup> activated ClC\u20107\/Ostm 1 under acidic extracellular conditions, as well as under conditions of low intracellular chloride. Activation is conserved in ClC\u20107<jats:sup>Y713C<\/jats:sup>, a variant displaying disrupted PI(3,5)P<jats:sub>2<\/jats:sub> inhibition. Detailed biophysical analysis of disease\u2010associated ClC\u20106 and ClC\u20107 gain\u2010of\u2010function (GoF) variants, ClC\u20106<jats:sup>Y553C<\/jats:sup> and ClC\u20107<jats:sup>Y713C<\/jats:sup>, and the ClC\u20107<jats:sup>Y577C<\/jats:sup> and ClC\u20106<jats:sup>Y781C<\/jats:sup> correlates, identified additional functional nuances distinguishing ClC\u20106 and ClC\u20107. ClC\u20107<jats:sup>Y577C<\/jats:sup> recapitulated GoF produced by ClC\u20106<jats:sup>Y553C<\/jats:sup>. ClC\u20106<jats:sup>Y781C<\/jats:sup> displayed transport activation qualitatively similar to ClC\u20107<jats:sup>Y713C<\/jats:sup>, although current density did not differ from that of wild\u2010type ClC\u20106. Finally, rClC\u20107<jats:sup>R760Q<\/jats:sup>, homologous to hClC\u20107<jats:sup>R762Q<\/jats:sup>, an osteopetrosis variant with fast gating kinetics, appeared indifferent to extracellular Cl<jats:sup>\u2212<\/jats:sup>, identifying altered Cl<jats:sup>\u2212<\/jats:sup> sensitivity as a plausible mechanism underlying disease. Collectively, the present studies underscore the distinct roles of ClC\u20106 and ClC\u20107 within the context of their respective localization to late endosomes and lysosomes. In particular, we suggest the atypical inhibition of ClC\u20107 by luminal Cl<jats:sup>\u2212<\/jats:sup> serves to limit excessive intraluminal Cl<jats:sup>\u2212<\/jats:sup> accumulation.\n<jats:boxed-text content-type=\"graphic\" position=\"anchor\"><jats:graphic xmlns:xlink=\"http:\/\/www.w3.org\/1999\/xlink\" mimetype=\"image\/png\" position=\"anchor\" specific-use=\"enlarged-web-image\" xlink:href=\"graphic\/tjp15807-gra-0001-m.png\"><jats:alt-text>image<\/jats:alt-text><\/jats:graphic><\/jats:boxed-text><\/jats:p><\/jats:sec><jats:sec><jats:title>Key points<\/jats:title><jats:p><jats:list list-type=\"bullet\">\n<jats:list-item><jats:p>ClC\u20106 and ClC\u20107 are late endosomal and lysosomal 2 Cl<jats:sup>\u2212<\/jats:sup>\/1 H<jats:sup>+<\/jats:sup> exchangers, respectively. When targeted to the plasma membrane, both activate slowly at positive voltages.<\/jats:p><\/jats:list-item>\n<jats:list-item><jats:p>ClC\u20106 activity is decreased in low extracellular (i.e. luminal) chloride, whereas ClC\u20107 is activated by low luminal chloride, even at acidic pH.<\/jats:p><\/jats:list-item>\n<jats:list-item><jats:p>The functional gain\u2010of\u2010function phenotypes of the ClC\u20106 and ClC\u20107 disease mutations ClC\u20106<jats:sup>Y553C<\/jats:sup> and ClC\u20107<jats:sup>Y715C<\/jats:sup> are maintained when introduced in their respective homologues, ClC\u20107<jats:sup>Y577C<\/jats:sup> and ClC\u20106<jats:sup>Y781C<\/jats:sup>, with all mutations retaining chloride dependence of the respective wild type (WT).<\/jats:p><\/jats:list-item>\n<jats:list-item><jats:p>An osteopetrosis mutation of ClC\u20107 displaying fast gating kinetics (R762Q) was less sensitive to extracellular chloride compared to WT.<\/jats:p><\/jats:list-item>\n<jats:list-item><jats:p>The opposing substrate dependences of ClC\u20106 and ClC\u20107 Cl<jats:sup>\u2212<\/jats:sup> \/ H<jats:sup>+<\/jats:sup> exchangers point to non\u2010overlapping physiological functions, leading us to propose that inhibition of ClC\u20107 by luminal chloride and protons serves to prevent osmotic stress imposed by hyper\u2010accumulation of chloride.<\/jats:p><\/jats:list-item>\n<\/jats:list><\/jats:p><\/jats:sec>","DOI":"10.1113\/jp285431","type":"journal-article","created":{"date-parts":[[2023,11,8]],"date-time":"2023-11-08T10:31:54Z","timestamp":1699439514000},"page":"5635-5653","update-policy":"https:\/\/doi.org\/10.1002\/crossmark_policy","source":"Crossref","is-referenced-by-count":7,"title":["Distinct ClC\u20106 and ClC\u20107 Cl<sup>\u2212<\/sup> sensitivities provide insight into ClC\u20107's role in lysosomal Cl<sup>\u2212<\/sup> homeostasis"],"prefix":"10.1113","volume":"601","author":[{"given":"Maria Antonietta","family":"Coppola","sequence":"first","affiliation":[{"name":"Institute of Biophysics CNR  Genoa Italy"},{"name":"Department of Pharmacy\u2013Drug Sciences University of Bari \u2018Aldo Moro\u2019  Bari Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Paola","family":"Gavazzo","sequence":"additional","affiliation":[{"name":"Institute of Biophysics CNR  Genoa Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Ilaria","family":"Zanardi","sequence":"additional","affiliation":[{"name":"Institute of Biophysics CNR  Genoa Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Abraham","family":"Tettey\u2010Matey","sequence":"additional","affiliation":[{"name":"Institute of Biophysics CNR  Genoa Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Antonella","family":"Liantonio","sequence":"additional","affiliation":[{"name":"Department of Pharmacy\u2013Drug Sciences University of Bari \u2018Aldo 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