ClC-5, the chloride channel mutated in Dent’s disease, colocalizes with the proton pump in endocytotically active kidney cells

Abstract

Loss-of-function mutations of the ClC-5 chloride channel lead to Dent's disease, a syndrome characterized by low molecular weight proteinuria, hypercalciuria, and kidney stones. We show that ClC-5 is expressed in renal proximal tubule cells, which normally endocytose proteins passing the glomerular filter. Expression is highest below the brush border in a region densely packed with endocytotic vesicles, where ClC-5 colocalizes with the H ؉ -ATPase and with internalized proteins early after uptake. In intercalated cells of the collecting duct it again localizes to apical intracellular vesicles and colocalizes with the proton pump in ␣-intercalated cells. In transfected cells, ClC-5 colocalizes with endocytosed ␣ 2 -macroglobulin. Cotransfection with a GTPasedeficient rab5 mutant leads to enlarged early endosomes that stain for ClC-5. We suggest that ClC-5 may be essential for proximal tubular endocytosis by providing an electrical shunt necessary for the efficient acidification of vesicles in the endocytotic pathway, explaining the proteinuria observed in Dent's disease.

Mechanisms of Exocytosis in Insulin‐Secreting B‐Cells and Glucagon‐Secreting A‐Cells

“…Indeed, regulation of vesicle acidification by chloride counter-ion flux seems to be a common phenomenon (al Awqati et al 1992). For example, ClC-5 was found on endocytic vesicles of renal cells (Günther et al 1998), and disruption of this channel impaired endocytosis and vesicle acidification (Piwon et al 2000).…”

Molecular Mechanisms of Primary Hypercalciuria

“…SDS-PAGE analysis of the urine from both the male and female knockouts demonstrated increased levels of many urinary proteins, including vitamin D-binding protein (DBP), albumin, and retinol-binding protein, suggesting that CLC-5 is needed for endocytic retention of small proteins, an established property of proximal tubule. Gunther et al (88) localized CLC-5 in the proximal tubule by immunocytochemistry; although diffuse CLC-5 staining can be seen throughout the cell, higher concentrations are seen in vesicles adjacent to the brush border membrane, a region known to be important for endocytic activity. CLC-5 colocalizes with H ϩ -ATPase, and this pairing is important for acidification of endocytotic vesicles (88); CLC-5 is thought to act as a shunt allowing diffusion of Cl Ϫ into the endosome, decreasing the accumulation of positive charges and allowing for greater acidification.…”

Renal Collecting Duct Epithelial Cells React to Pyelonephritis-Associated Escherichia coli by Activating Distinct TLR4-Dependent and -Independent Inflammatory Pathways

“…1F). To further characterize the bacterial attachment to collecting duct cells composed of principal and intercalated cells, sections were double stained with Abs raised against E. coli and the water channel AQP-2 or the chloride channel ClC-5 expressed in the principal and intercalated cells, respectively (35,38). AL10 (Fig.…”