Abstract 078: Human Gain-of-function Mutation W521r In The Enac α-subunit Contributes To Salt-sensitive Hypertension In A Sex-specific Manner

Abstract

The epithelial Na + channel (ENaC) plays a key role in regulating the extracellular fluid volume and blood pressure. Gain-of-function mutations in ENaC subunits are associated with hypertensive disorders including Liddle syndrome. We previously demonstrated that in male mice, dendritic cell ENaC mediates NADPH oxidase activation and increased accumulation of Isolevuglandins (IsoLGs), which act as neoantigens, promoting T cell activation and salt-induced hypertension. The mechanism by which dendritic cell ENaC is regulated, and the role of sex as a biological variable is still yet to be defined. One of the mechanisms by which ENaC is regulated is through sodium self-inhibition. We hypothesized that sodium self-inhibition plays a sex-specific role in regulating ENaC leading to salt-sensitive hypertension. To test this hypothesis, we generated mice with a gain-of-function mutation of a single nucleotide variant (W521R) in ENaC α-subunit using CRISPR/Cas9 in the wild-type (WT) salt-sensitive129/sv background. These mutant mice lack the sodium self-inhibition of ENaC. WT littermate male and female mice were used as controls. Using telemetry blood pressure monitoring, we found that WT males developed salt-induced hypertension, but WT females were protected (124.3 ± 5.15 vs. 95.37 ± 4.882 mmHg, p=0.0114). Moreover, W521R male mutants had elevated mean arterial pressure in response to 3 weeks of high salt-feeding (4% NaCl) compared to the salt-sensitive WT littermate males (169.3 ± 27.69 vs. 124.3 ± 5.15 mmHg, p= 0.0024). Similar to WT females, female W521R mice were protected from salt-induced blood pressure elevation (102.3± 5.23 mmHg). Using flow cytometry, we found that high Na + increased dendritic cell IsoLGs production in male W521R mice compared to littermate controls (3.97 ± 1.68% vs. 1.01 ± 0.08 % of dendritic cells, p=0.0386). Our findings suggest that W521R gain-of-function mutation contributes to inflammation and hypertension in male but not female mice.