Distinct Smooth Muscle Anchoring Proteins Forming Separated Nanodomains Regulate Blood Pressure

Ca 2+ influx through the transient receptor potential vanilloid 4 (TRPV4) channel is a well-established pathway in vascular smooth muscle cells (SMCs). Previously, we discovered two separate SMC TRPV4 (TRPV4 SMC ) channel subpopulations: constrictor TRPV4 SMC channels that are activated by α1 adrenergic receptors (a1AR) through protein kinase C (PKC) and dilator TRPV4 SMC channels that are activated by intraluminal pressure and couple with Ca 2+ -activated K + (BK) channels. However, the underlying mechanism for the formation of these TRPV4 SMC signaling nanodomains is unclear. AKAP150 (A kinase anchoring protein 150), a PKC-anchoring protein, is essential for PKC activation of TRPV4 SMC channels, and Caveolin-1 (Cav1) has been linked to enhanced activity of TRPV4 and BK channels. We hypothesized that distinct anchoring proteins facilitate the formation of spatially separated TRPV4 SMC signaling nanodomains. Therefore, we tested the possibility that AKAP150 mediates α1AR–TRPV4 SMC signaling, and Cav1 provides a signaling scaffold for the intraluminal pressure-activated TRPV4 SMC –BK signaling. The tamoxifen-inducible, SMC-specific AKAP150 KO (AKAP150 SMCKO ) mice showed lower resting blood pressure, suggesting that AKAP150 SMC increases the resting blood pressure. On the contrary, Cav1 SMCKO mice showed elevated resting blood pressure, suggesting that Cav1 SMC decreases blood pressure. Furthermore, phenylephrine (PE, a1AR agonist)-induced TRPV4 SMC currents and increase in blood pressure (1 mg/kg PE, intraperitoneal), and nerve stimulation-induced (electrical pulses; 50–150 V, 0.25-ms pulse, 15 Hz) TRPV4 SMC channel activity were absent in AKAP150 SMCKO mice, but not in Cav1 SMCKO mice. TRPV4 channel-activated BK current was abrogated in SMCs from Cav1 SMCKO mice, but not in SMCs from AKAP150 SMCKO mice. Together, these data supported the concept that anchoring proteins AKAP150 and Cav1 are required to form constrictor and dilator TRPV4 SMC signaling nanodomains, respectively. Studies in other cell types have shown that mechanosensitive Piezo1 channels can increase the activity of TRPV4 channels. Therefore, we determined whether Piezo1 is required for intraluminal pressure-activated dilator TRPV4 SMC signaling. We postulated that intraluminal-pressure activates Cav1-scaffolded Piezo1 SMC –TRPV4 SMC –BK channel signaling. Piezo1 SMCKO mice showed a loss of intraluminal pressure-induced TRPV4 SMC channel activity and increased myogenic constriction. Importantly, Yoda1 (Piezo1 activator)-induced increase in BK current was absent in SMCs from Cav1 SMCKO , TRPV4 SMCKO , and Piezo1 SMCKO mice, but not AKAP150 SMCKO mice. Meanwhile, the activity of Piezo1 SMC channels was unaltered in Cav1 SMCKO mice. Together, our results suggest that AKAP150 SMC facilitates constrictor α1AR–PKC– TRPV4 SMC signaling and Cav1 SMC promotes dilator Piezo1 SMC –TRPV4 SMC —BK signaling. Collectively, our data identify the anchoring proteins involved in the formation of distinct Ca 2+ signaling nanodomains with opposite effects on blood pressure. This work was supported by funding from the AHA to YLC (POST833691), NIDDK K99 to YLC (DK138271), the National Institutes of Health to SKS (HL146914, HL142808, and HL147555). 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.