Mice lacking γENaC palmitoylation sites maintain benzamil-sensitive Na+ transport despite reduced channel activity

• DOI: 10.1172/jci.insight.172051
• Publication Date: 2023-09-14T16:03:51Z
• Authors: Andrew J. Nickerson; Stephanie M. Mutc...; Shaohu Sheng; Natalie A. Cox; Evan C. Ray; Ossama B. Kashlan; Marcelo D. Carattino; Allison L. Marciszyn; Aaliyah Winfrey; Sebastien Gingras; Annet Kirabo; Rebecca P. Hughey; Thomas R. Kleyman
• Keywords: Palmitoylation; Epithelial sodium channel; BK channel; Amiloride

Epithelial Na+ channels (ENaCs) control extracellular fluid volume by facilitating absorption across transporting epithelia. In vitro studies showed that Cys-palmitoylation of the γ ENaC subunit is a major regulator channel activity. We tested whether palmitoylation sites are necessary for function in vivo generating mice lacking palmitoylated cysteines (γC33A,C41A) using CRISPR-Cas9 technology. ENaCs dissected kidney tubules from γC33A,C41A had reduced open probability compared to wild type (WT) littermates maintained on either standard or Na+-deficient diets. Male mutant also higher aldosterone levels than WT following restriction. However, did not have amiloride-sensitive currents distal colon benzamil-induced natriuresis mice. identified second, larger conductance cation nephron with biophysical properties distinct ENaC. The activity this was Na+-restricted versus and blocked benzamil, providing possible compensatory mechanism prototypic function. conclude required vivo, but amiloride/benzamil-sensitive transport colon.