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

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.

• Authors: Nobuhiko Satoh, Hideomi Yamada, Osamu Yamazaki, Masashi Suzuki, Motonobu Nakamura, Atsushi Suzuki, Akira Ashida, Daisuke Yamamoto, Yoshitsugu Kaku, Takashi Sekine, George Seki, Shoko Horita
• Journal: Pflugers Archiv : European journal of physiology (Pflugers Arch) Vol. 468 Issue 7 Pg. 1183-1196 (07 2016) ISSN: 1432-2013 [Electronic] Germany
• PMID: 27044412 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• CLC-5 chloride channel
• Chloride Channels
• Vacuolar Proton-Translocating ATPases

Topics

• Animals
• Cell Line
• Cell Membrane (metabolism)
• Child
• Chloride Channels (genetics, metabolism)
• Dent Disease (genetics, metabolism)
• Endocytosis (physiology)
• Female
• HEK293 Cells
• Homeostasis (physiology)
• Humans
• Ion Transport (physiology)
• Kidney Tubules, Proximal (metabolism)
• Male
• Mutation (genetics)
• Oocytes (metabolism)
• Vacuolar Proton-Translocating ATPases (metabolism)
• Xenopus laevis (metabolism)