ClC-Kb Pore Mutation Disrupts Glycosylation and Triggers Distal Tubular Remodeling

Authors

Yogita Sharma
Robin Lo
Viktor N Tomilin
Kotdaji Ha
Holly Deremo
Aishwarya V Pareek
Wuxing Dong
Xiaohui Liao
Svetlana Lebedeva
Vivek Charu
Neeraja Kambham
Kerim Mutig
Oleh Pochynyuk
Vivek Bhalla

Language

English

Publication Date

11-22-2024

Journal

JCI Insight

DOI

10.1172/jci.insight.175998

PMID

39405114

PMCID

PMC11601903

PubMedCentral® Posted Date

11-22-2024

PubMedCentral® Full Text Version

Post-print

Abstract

Mutations in the CLCNKB gene (1p36), encoding the basolateral chloride channel ClC-Kb, cause type 3 Bartter syndrome. We identified a family with a mixed Bartter/Gitelman phenotype and early-onset kidney failure and by employing a candidate gene approach, identified what we believe is a novel homozygous mutation (CLCNKB c.499G>T [p.Gly167Cys]) in exon 6 of CLCNKB in the index patient. We then validated these results with Sanger and whole-exome sequencing. Compared with wild-type ClC-Kb, the Gly167Cys mutant conducted less current and exhibited impaired complex N-linked glycosylation in vitro. We demonstrated that loss of Gly-167, rather than gain of a mutant Cys, impairs complex glycosylation, but that surface expression remains intact. Moreover, Asn-364 was necessary for channel function and complex glycosylation. Morphologic evaluation of human kidney biopsies revealed typical basolateral localization of mutant Gly167Cys ClC-Kb in cortical distal tubular epithelia. However, we detected attenuated expression of distal sodium transport proteins, changes in abundance of distal tubule segments, and hypokalemia-associated intracellular condensates from the index patient compared with control nephrectomy specimens. The present data establish what we believe are novel regulatory mechanisms of ClC-Kb activity and demonstrate nephron remodeling in humans, caused by mutant ClC-Kb, with implications for renal electrolyte handling, blood pressure control, and kidney disease.

Keywords

Humans, Glycosylation, Chloride Channels, Male, Female, Mutation, Pedigree, Kidney Tubules, Distal, Bartter Syndrome, HEK293 Cells, Adult, Nephrology, Chronic kidney disease, Ion channels

Published Open-Access

yes

Recommended Citation

Sharma, Yogita; Lo, Robin; Tomilin, Viktor N; et al., "ClC-Kb Pore Mutation Disrupts Glycosylation and Triggers Distal Tubular Remodeling" (2024). Faculty, Staff and Student Publications. 6432.
https://digitalcommons.library.tmc.edu/uthgsbs_docs/6432