Expression of the kidney anion exchanger 1 affects WNK4 and SPAK phosphorylation and results in claudin-4 phosphorylation

Rawad Lashhab; Grace Essuman; Maria Chavez-Canales; R Todd Alexander; Emmanuelle Cordat

doi:10.1016/j.heliyon.2023.e22280

Expression of the kidney anion exchanger 1 affects WNK4 and SPAK phosphorylation and results in claudin-4 phosphorylation

Heliyon. 2023 Nov 13;9(11):e22280. doi: 10.1016/j.heliyon.2023.e22280. eCollection 2023 Nov.

Authors

Rawad Lashhab¹, Grace Essuman¹, Maria Chavez-Canales², R Todd Alexander^{1

3}, Emmanuelle Cordat¹

Affiliations

¹ Department of Physiology and Membrane Protein Disease Research Group, University of Alberta, Edmonton, Alberta, Canada.
² Unidad de Investigación UNAM-INCICh, Instituto Nacional de Cardiología Ignacio Chávez and Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Tlalpan, Mexico City, 14080, Mexico.
³ Department of Pediatrics, University of Alberta, Edmonton, Alberta, Canada.

Abstract

In the renal collecting ducts, chloride reabsorption occurs through both transcellular and paracellular pathways. Recent literature highlights a functional interplay between both pathways. We recently showed that in polarized inner medullary collecting duct cells, expression of the basolateral kidney anion exchanger 1 (kAE1) results in a decreased transepithelial electrical resistance (TEER), in a claudin-4 dependent pathway. Claudin-4 is a paracellular sodium blocker and chloride pore. Here, we show that kAE1 expression in mouse inner medullary collecting duct cells triggers WNK4, SPAK and claudin-4 phosphorylation. Expression of a functionally dead kAE1 E681Q mutant has no effect on phosphorylation of these proteins. Expression of a catalytically inactive WNK4 D321A or chloride-insensitive WNK4 L319F mutant abolishes kAE1 effect on TEER, supporting a contribution of WNK4 to the process. We propose that variations of the cytosolic pH and chloride concentration upon kAE1 expression alter WNK4 kinase activity and tight junction properties.

Keywords: Blood pressure; Chloride conservation; Claudin; Collecting duct; Distal nephron; Epithelium; Intercalated cells; Kidney; Membrane protein; Paracellular proteins; Sodium conservation; Tight junctions; Transporters.