title: A Novel voltage-dependent chloride current activated by extracellular acidic pH in cultured rat Sertoli cells.
abstract: Sertoli cells from mammalian testis are key cells involved in development and maintenance of stem cell spermatogonia as well as secretion of a chloride- and potassium-rich fluid into the lumen of seminiferous tubules. Using whole-cell patch clamp experiments, a novel chloride current was identified. It is activated only in the presence of an extracellular acidic pH, with an estimated half-maximal activation at pH 5.5. The current is strongly outwardly rectifying, activated with a fast time-dependent onset of activation but a slow time-dependent kinetic at depolarization pulses. The pH-activated chloride current was not detected at physiological or basic pH and is not sensitive to intracellular or extracellular Ca2+ variation. Diphenylamine-2-carboxylic acid and 4,4'-diisothiocyanatostilbene-2,2'-disulfonic acid blocked the induced currents, and its anionic selectivity sequence was Cl- > Br- > I-> gluconate. We have performed a reverse transcription-PCR analysis to search for voltage-dependent chloride rClC channels in cultured rat Sertoli cells. Among the nine members of the family only rClC-2, rClC-3, rClC-6, and rClC-7 have been identified. The inwardly rectifying rClC-2 chloride current was activated by hyperpolarization but not by pH variation. A different depolarization-activated outwardly rectifying chloride current was activated only by hypotonic challenge and may correspond either to rClC-3 or rClC-6. Immunolocalization experiments demonstrate that rClC-7 resides in the intracellular compartment of Sertoli cells. This study provides the first functional identification of a native acid-activated chloride current. Based on our molecular analysis of rClC proteins, this new chloride current does not correspond to rClC-2, rClC-3, rClC-6, or rClC-7 channels. The potential physiological role of this native current in an epithelial cell from the reproductive system is discussed.
authors.affiliation: Laboratoire des Biomembranes et Signalisation Cellulaire CNRS UMR 6558, Université de Poitiers, 40 Avenue du Recteur Pineau, Poitiers, France.
authors.forename: Céline
authors.initials: C
authors.lastname: Auzanneau
authors.forename: Vincent
authors.initials: V
authors.lastname: Thoreau
authors.forename: Alain
authors.initials: A
authors.lastname: Kitzis
authors.forename: Frédéric
authors.initials: F
authors.lastname: Becq
mesh_terms: D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid / Q000494:pharmacology; D000818:Animals; D000090007:CLC-2 Chloride Channels; D002118:Calcium / Q000378:metabolism; D002478:Cells, Cultured; D018118:Chloride Channels / Q000032:analysis / Q000235:genetics / Q000502:physiology*; D002712:Chlorides / Q000378:metabolism; D004553:Electric Conductivity; D015870:Gene Expression; D006863:Hydrogen-Ion Concentration; D007038:Hypotonic Solutions; D008297:Male; D009865:Oocytes / Q000378:metabolism; D018408:Patch-Clamp Techniques; D012333:RNA, Messenger / Q000032:analysis; D051381:Rats; D017208:Rats, Wistar; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012708:Sertoli Cells / Q000737:chemistry / Q000502:physiology*; D014162:Transfection; D014982:Xenopus laevis; D062367:ortho-Aminobenzoates / Q000494:pharmacology
chemical_list: D000090007:CLC-2 Chloride Channels; D018118:Chloride Channels; D002712:Chlorides; C115376:ClC-3 channel; C490801:Clcn6 protein, rat; C490802:Clcn7 protein, rat; D007038:Hypotonic Solutions; D012333:RNA, Messenger; D062367:ortho-Aminobenzoates; C001209:fenamic acid; D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid; D002118:Calcium