Piezo1 regulates expression of BK and TRPV4 channels in mouse cortical collecting duct (CCD)

Abstract

Within the CCD, an acute increase in tubular fluid flow rate (TFFR) leads to an immediate high amplitude increase in [Ca 2+ ] i , due to release of IP3-sensitive internal Ca 2+ stores coupled to extracellular Ca 2+ entry at the basolateral membrane in both principal (PC) and intercalated (IC) cells therein (Liu et al., 2003, 2005, 2007). This is followed by a decay in [Ca 2+ ] i to a sustained plateau elevation due, at least in part, to luminal Ca 2+ entry through TRPV4 (Berrout et al., 2012). This flow-induced increase in [Ca 2+ ] i is necessary for BK channel-mediated flow induced K + secretion (FIKS) in the microperfused mammalian CCD. We generated a mouse with IC-specific targeted deletion of the mechanosensitive Ca 2+ permeable channel, Piezo1, which is expressed on the basolateral membranes of PCs and ICs in the mouse CCD (Dalghi et al., 2019). Microperfused CCDs isolated from these IC-PIEZO1-KO mice fed a high K (HK, 5% K + ) diet and subject to an increase in TFFR did not exhibit either a peak or plateau elevation in [Ca 2+ ] i in response to flow, and FIKS was eliminated. The absence of FIKS and the plateau elevation in [Ca 2+ ] during sustained flow in the CCDs of KO mice led us to examine whether BK and TRPV4 channel expression was impacted by deletion of PIEZO1.Indirect immunofluorescence (IF) staining was performed to examine expression and localization of the BK and TRPV4 channels in PCs and ICs of IC-PIEZO1-KO mice. Whole cell and apical + subapical fluorescence intensities in cryosections were analyzed using LAS X software from a total of 3 male and 3 female control mice and 3 male and 3 female IC-PIEZO1-KO mice fed HK diet x 10d.IF analysis showed reduced whole cell BKα expression in ICs of both male (p≤0.05) and female (p≤0.01) IC-PIEZO1-KO mice. We also saw reduced BKα expression in PCs from female but not male KOs. In addition, ICs in female but not male KO mice had reduced whole cell TRPV4 expression vs. controls (p≤0.01). Also, whole cell expression of TRPV4 in PCs from female KO mice was reduced vs. female controls (p≤0.01). The ratio of apical-to-whole cell expression of BKα was similar in PCs and ICs of KO and control mice. Male, but not female, KO mice had modestly reduced apical TRPV4 expression in PCs vs. controls (p≤0.01). Piezo1 plays a role in the regulation of BK and TRPV4 channel expression in CCDs. In addition, sex differences exist in whole cell expression of these channels in response to IC-selective deletion of PIEZO1. R01 DK038470 (TK, LMS); R01 DK129285 (TK, LMS); P30 DK079307 (TK) This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.