A pure chloride channel mutant of CLC-5 causes Dent’s disease via insufficient V-ATPase activation

Nobuhiko Satoh, Hideomi Yamada, Osamu Yamazaki, Masashi Suzuki, Motonobu Nakamura, Atsushi Suzuki, Akira Ashida, Daisuke Yamamoto, Yoshitsugu Kaku, Takashi Sekine, George Seki, Shoko Horita

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Abstract

Dent’s disease is characterized by defective endocytosis in renal proximal tubules (PTs) and caused by mutations in the 2Cl/H+ exchanger, CLC-5. However, the pathological role of endosomal acidification in endocytosis has recently come into question. To clarify the mechanism of pathogenesis for Dent’s disease, we examined the effects of a novel gating glutamate mutation, E211Q, on CLC-5 functions and endosomal acidification. In Xenopus oocytes, wild-type (WT) CLC-5 showed outward-rectifying currents that were inhibited by extracellular acidosis, but E211Q and an artificial pure Cl channel mutant, E211A, showed linear currents that were insensitive to extracellular acidosis. Moreover, depolarizing pulse trains induced a robust reduction in the surface pH of oocytes expressing WT CLC-5 but not E211Q or E211A, indicating that the E211Q mutant functions as a pure Cl channel similar to E211A. In HEK293 cells, E211A and E211Q stimulated endosomal acidification and hypotonicity-inducible vacuolar-type H+-ATPase (V-ATPase) activation at the plasma membrane. However, the stimulatory effects of these mutants were reduced compared with WT CLC-5. Furthermore, gene silencing experiments confirmed the functional coupling between V-ATPase and CLC-5 at the plasma membrane of isolated mouse PTs. These results reveal for the first time that the conversion of CLC-5 from a 2Cl/H+ exchanger into a Cl channel induces Dent’s disease in humans. In addition, defective endosomal acidification as a result of insufficient V-ATPase activation may still be important in the pathogenesis of Dent’s disease.

Original languageEnglish
Pages (from-to)1-14
Number of pages14
JournalPflugers Archiv European Journal of Physiology
DOIs
Publication statusAccepted/In press - 2016 Apr 5

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Keywords

  • CLC-5
  • Dent’s disease
  • Endocytosis
  • Endosomal acidification
  • Gating glutamate
  • V-ATPase

ASJC Scopus subject areas

  • Physiology
  • Clinical Biochemistry
  • Physiology (medical)

Cite this

Satoh, N., Yamada, H., Yamazaki, O., Suzuki, M., Nakamura, M., Suzuki, A., Ashida, A., Yamamoto, D., Kaku, Y., Sekine, T., Seki, G., & Horita, S. (Accepted/In press). A pure chloride channel mutant of CLC-5 causes Dent’s disease via insufficient V-ATPase activation. Pflugers Archiv European Journal of Physiology, 1-14. https://doi.org/10.1007/s00424-016-1808-7