AKAP150 and Caveolin 1 underlie the formation of distinct TRPV4 signaling microdomains in vascular smooth muscle cells
Authors: Chen Yen-Lin , Daneva Zdravka , Maniselvan Kuppusamy , Eliska Klimentova , Sonkusare Swapnil 
Published: May 2023

Transient receptor potential vanilloid 4 (TRPV4) channel is a well-established Ca2+ influx pathway in arterial smooth muscle cells (SMCs), although its roles in blood pressure regulation have remained unclear. We recently discovered two separate SMC TRPV4 (TRPV4SMC) channel subpopulations: constrictor TRPV4SMC channels that are activated by α1 adrenergic receptors (α1AR) through protein kinase C (PKC) signaling, and dilator TRPV4SMC channels that are activated by intraluminal pressure and couple with downstream Ca2+-activated BK channels. However, the underlying mechanism for the formation of these TRPV4SMC signaling microdomains is unclear. We hypothesized that distinct anchoring proteins facilitate the formation of spatially separated TRPV4SMC signaling microdomains. PKC-anchoring protein, AKAP150 (A kinase anchoring protein 150), is essential for PKC activation of TRPV4SMC channels. Moreover, Caveolin-1 (Cav1) has been linked to enhanced activity of TRPV4 and BK channels. Therefore, we tested the possibility that AKAP150 mediates α1AR-induced activation of constrictor TRPV4SMC channels, and Cav1 provides a signaling scaffold for the intraluminal pressure-activated TRPV4SMC–BK channel signaling. Radiotelemetric recordings showed lower resting blood pressure in tamoxifen-inducible, SMC-specific AKAP150-/- (AKAP150SMC -/-) mice, suggesting that AKAP150SMC increases the resting blood pressure. On the contrary, Cav1SMC -/- mice showed elevated resting blood pressure, suggesting that Cav1SMC decreases blood pressure. Furthermore, phenylephrine (PE, α1AR agonist)-induced TRPV4SMC currents and increase in blood pressure (1 mg/kg PE, intraperitoneal) were absent in AKAP150SMC -/- mice, but not in Cav1SMC - /- mice. TRPV4 channel-activated BK current was abrogated in SMCs from Cav1SMC -/- mice, but not in SMCs from AKAP150SMC -/- mice. Together, these data supported that AKAP150 and Cav1 are required for the formation of constrictor and dilator TRPV4SMC signaling microdomains, respectively. We then determined whether Piezo1 is required for intraluminal pressure-activation of the dilator TRPV4SMC channels. Studies in other cell types have shown that mechanosensitive Piezo1 channels can increase the activity of TRPV4 channels. Therefore, we postulated that intraluminal pressure activates Cav1-scaffolded Piezo1SMC–TRPV4SMC–BK channel signaling. Intraluminal pressure-induced TRPV4SMC channel activity was lost in MAs from Piezo1SMC -/- mice and Cav1SMC -/- mice. Importantly, Yoda1 (Piezo1 activator)-induced increase in BK current was absent in SMCs from Cav1SMC -/- and TRPV4SMC -/­- mice, but not AKAP150SMC -/- mice. Together, our results support that AKAP150SMC anchoring of PKC mediates α1AR activation of TRPV4SMC channels and that Cav1 provides a signaling scaffold for Piezo1SMC–TRPV4SMC–BK channel signaling. Collectively, our data identify the anchoring proteins involved in the formation of TRPV4 Ca2+ signaling microdomains with opposite effects on blood pressure. This work was supported by funding from the American Heart Association to Dr Chen (grant POST833691), and grants from the National Institutes of Health to Dr Sonkusare (HL146914, HL142808, and HL147555). 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.