#4375 LANOSTEROL SYNTHASE RS2254524 POLYMORPHISM MODULATES SALT SENSITIVITY AND RENAL EXPRESSION IN A NOVEL MICE MODEL, LSSV643L/V643L

Abstract

Abstract Background and Aims The blood pressure (BP) response to different salt intakes (salt sensitivity-SS), shows variability among individuals, with more frequency in hypertensives compared to the general population. Elevated levels of the Endogenous Ouabain (EO) have been associated with hypertension (HT) and SS. We characterized the missense variation rs2254524 (Val642Leu; C>A) of the Lanosterol Synthase gene (LSS) coding for an enzyme in steroid biosynthesis, since AA patients on a low-salt diet showed a greater reduction in BP compared to the LSS CC, with only CC having an increase in plasma EO. Moreover, AKI incidence following cardiovascular surgery was greater among those with the LSS rs2254524 AA genotype than in those with the CC genotype. We aim at dissecting the functional correlation between LSS polymorphism, EO, SS-HT, and renal function. Method We generated by CRISPR-Cas9 a knock-in mouse model carrying the Lss V643L (LssV643L/V643L), homologous to V642L to dissect the functional correlation between LSS polymorphism, EO and salt-sensitive hypertension, and kidney expression. Male mice were fed with a normal-salt diet (0.5% NaCl), high-salt diet (4% NaCl), or low-salt diet (<0.03% Na) and BP was measured every two days by the tail-cuff system. Results LssV643L/V643L mice were viable, healthy, and undistinguishable phenotypically from WT. At baseline, the Lss AA affected kidney weight that was significantly enlarged at 3 (p = 0.02) and 12 months of age, compared to WT (kidney p = 0.04; liver p = 0.003). The Lss V643L mutation did not affect EO and SBP at 3 and 12 months, per se, but affects SBP responsiveness to salt intake. Indeed, we observed an increased SBP upon a high-salt diet only in LssV643L/V643L mice 12 months old compared to the control diet (p = 0.01). Moreover, the 12-month-old LssV643L/V643L mice in high-salt diet showed cardiac hypertrophy and showed a higher incidence of heart fibrosis. At 12 months, in the adrenal gland of LssV643L/V643L mice, Lss mRNA level was reduced upon high-salt diet (p = 0.03), while RNA-seq analysis of renal differentially expressed genes revealed a different regulation of multiple Slc genes, both in control and high-salt diet, but also of Cbr2, and Arhgap26. Conclusion The new LssV643L/V643L mouse model resembles the SS-HT phenotype together with EO non-responsiveness observed in HT patients, thus providing a good model of SS-HT. Our results reveal a role of Lss gene in the regulation of BP upon salt stimulus, and its influence at renal level at 3 and 12 months of age.