Abstract 069: Klf2, A Transcriptional Component Of The Renin Cell Baroreceptor

Abstract

Background: Renin regulates blood pressure (BP) and fluid homeostasis. Renin cells harbor a pressure sensor, the renin cell baroreceptor that controls renin synthesis and release. We recently discovered that the renin cell baroreceptor is a nuclear mechanotransducer within the renin cells that transmits external pressures to chromatin and regulates Ren1 expression. However, which transcription factors (TF) regulate renin expression during pressure sensing remains unclear. Objective: Define the responsible TFs for Ren1 as part of the renin cell baroreceptor. Methods: Forkhead box protein D1 (FoxD1) expressing stromal cells are the progenitors for juxtaglomerular cells (JG), mesangial cells (MC), pericytes (PC), and vascular smooth muscle cells (VSMC) of the renal arteriole. We generated FoxD1-GC; R26R TdTomato mice, in which all FoxD1 + cells and their descendants are labeled with tdTomato reporter. We applied a surgical model of aortic coarctation (AoCo) between the roots of the left and right renal arteries and sorted tdTomato + cells from the cortices of the left kidney (LK, low pressure) and the right kidney (RK, high pressure). Then, we performed single-cell RNA-seq to identify candidate TFs activated at low pressure. Candidates were then validated and deleted in the renin cells of mice exposed to hypotensive conditions. Results: 1) By single-cell RNA-seq, FoxD1 + cells were clustered into JG, VSMC, MC and PC, and other cell types. Differentially expressed gene (DEG) analysis in LK compared to RK showed that Ren1 was the highest DEG in JG. In VSMC, DEG includes Ren1 and Kruppel-like factor 2 ( Klf2) , which showed the highest Log 2 fold change (0.36) among the major TFs. 2) We generated Klf2 fl/fl ; Ren1 dCre ( Klf2 cKO) mice, and found a 55.1% decrease of kidney cortices Ren1 mRNA expression by qPCR (n = 5, P=0.022) and reduced plasma renin levels by ELISA (40.1 ± 9.6 vs 15.1 ± 7.3 ng/mL, n = 12, P<0.001) compared to wild type mice. Klf2 cKO mice treated with captopril-added water (0.5 g/L) and a low Na + diet for 7 days displayed reduced renin immunostaining in the JG and along the afferent arterioles. Conclusion: We identified Klf2 as a key TF for Ren1 as a part of the renin cell baroreceptor. Experiments for Klf2 cKO mice with AoCo surgery are ongoing.