Mechanoregulation of nucleocytoplasmic trafficking of YAP in the mouse cortical collecting duct (CCD)

The distal nephron of the mammalian kidney, which includes the CCD, plays a major role in the final renal regulation of Na + absorption and K + secretion. We have previously reported that PIEZO1, a mechanosensitive cation channel, is expressed along the basolateral membrane of intercalated cells (ICs) and principal cells (PCs) in the CCD, where it mediates flow-induced basolateral Ca 2+ entry necessary to activate the apical BK channel in ICs mediating flow-induced K + secretion (FIKS) [Carrisoza-Gaytan et al, JCI 2024]. Furthermore, we showed that a high K + diet increases expression of the pore-forming BKα subunit in wild-type (WT) mice [Najjar et al, AJP Renal 2005], while targeted deletion of PIEZO1 in ICs reduces BKα protein expression in ICs in both male and female mice [Carrisoza-Gaytan et al, JCI 2024]. These observation suggest that PIEZO1 plays a role in regulating BKα transcription/translation. Recently, PIEZO1 activation has been linked to increased nuclear targeting of Yes-associated protein (YAP), a co-activator that interacts with TEAD transcription factors (TEAD1–4) to regulate genes including BKα ( KCNMA1 ) [Duchemin et al, Elife 2009]. In bone, PIEZO1-dependent Ca 2+ signaling regulates YAP activation via Ppp3ca, which encodes calcineurin, an intracellular Ca 2+ sensor [Zhou et al, eLife 2020], while in kidney, YAP promotes transcription of Aqp2 and Aqp4 in proximal tubules contributing to the regulation of water absorption [Zhang et al, Kidney Int 2023]. Thus, we hypothesize that flow-mediated PIEZO1 activation in ICs regulates YAP-mediated transcription of BKα, contributing to enhanced K + secretion. To begin to test this, we sought to examine the expression of YAP in the CCD and assess whether increases in luminal flow alter nucleo-cytoplasmic trafficking of YAP, with nuclear localization indicating YAP activation. YAP expression and localization were examined in individual PCs and ICs in kidney cryo-sections prepared from WT C57Bl6/J male and female mice (n=3/group) following an acute I.P. saline injection (10% body weight) to induce volume expansion and increase urinary flow. Kidneys were harvested at 0, 1, 3, and 6 hours (h) post-injection, and YAP localization was assessed in ICs (V-ATPase+ cells) and PCs (Aqp2+ cells) by immunofluorescence using target-specific antibodies. The nuclear/cytoplasmic ratio of YAP fluorescence intensity was analyzed in individual cells (4-6 CCDs studied/time-point; 3-7 V-ATPase+ cells; 5-10 Aqp2+ cells studied/CCD) and compared to baseline (0 h) to determine any changes in YAP activation. YAP expression was detected in a primarily cytoplasmic (inactivated) distribution in ICs and PCs at baseline in both male and female mice. YAP activation (nuclear localization) was significantly increased by 13.8% (±2.6% SEM) in female but not male ICs at 3 h post-saline injection compared to control ( p≤ 0.05, 3 h vs 0 h), with a return to baseline at 6 h. The increase in urinary flow did not lead to YAP in PCs at all-time points examined. Our data indicate that increases in urinary flow rate associated with volume expansion enhance YAP nuclear translocation in ICs of female but not male kidney. Of note is that in mice feed a control K + diet, BKα expression is greater in female than in male CCDs [Lasaad et al, ASN 2024]. Our observations are consistent with sex-specific regulation of BKα expression by PIEZO1-mediated YAP activation, a hypothesis currently under investigation. R01 DK129285 R01 DK038470 This abstract was presented at the American Physiology Summit 2025 and is only available in HTML format. There is no downloadable file or PDF version. The Physiology editorial board was not involved in the peer review process.