Abstract Body: Kidneys are central to blood pressure regulation through the renin-angiotensin system. Renin-producing juxtaglomerular (JG) cells act as renal baroreceptors by controlling renin release according to the changes in perfusion pressure. Recent studies suggest that Piezo2 calcium channels may regulate the baroreceptor mechanism of renin release. However, our single-cell RNAseq and RNAScope analysis on adult kidneys showed a very low expression for Piezo2 in the JG cells. Since it is unclear if Piezo2 in the JG cells regulates renin expression and release, we defined the in vivo role of Piezo2 in the current study using Piezo2 conditional mutant mice. For this we generated Piezo2^fl/fl;Ren1^dCre, Piezo2^fl/del;Ren1^dCre and Piezo2^fl/fl;Akr1b7.Cre-Er^T2 mice.
Though we detected an efficient deletion of Piezo2 by RNAScope in the JG cells of the mutant kidneys, we did not observe a significant difference in the renin signals between the control and the mutant groups by renin immunostaining. q-RT-PCR of the kidney cortices to measure renin mRNA levels and renin-specific ELISA to quantify plasma renin levels also indicated no significant differences (NS) between the control and the mutant groups (Piezo2^fl/fl;Ren1^dCre - Relative renin mRNA levels: Control (n=11) 1.05±0.113 Mutants (n=6) 0.90±0.20, NS; Plasma renin levels (pg/ml): Control (n=11) 17472±3712 Mutants (n=6) 14934±3547, NS; Piezo2^fl/del;Ren1^dCre - Relative renin mRNA levels: Control (n=3) 0.98±0.13 Mutants (n=4) 1.04±0.19, NS; Plasma renin levels (pg/ml): Control (n=3) 20221±4303 Mutants (n=4) 15014±1901, NS). Furthermore, subjecting the mice to hypotension and volume depletion with captopril and a low salt diet for one week did not affect the renin expression due to Piezo2 deletion in the renin cells. Finally, our results from the aortic coarctation surgery model showed that Piezo2 deletion in the adult JG cells of Piezo2^fl/fl;Akr1b7.Cre-Er^T2 mice did not affect the changes in renin expression between the left and right kidneys in response to perfusion pressure (Relative renin mRNA levels: Control (n=11) LK-1.102 ±0.173 RK-0.316±0.046, p=0.002 Mutants (n=9) LK-1.191±0.266 RK-0.524±0.212, p=0.05). Collectively, our in vivo data shows that renin expression is unaffected during normal conditions and when homeostasis is threatened by hypotension, sodium depletion, or changes in blood pressure, indicating that Piezo2 channels are not necessary for renin synthesis and release to circulation in JG cells.