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Regulation of Pulmonary Arterial Pressure by Endothelial Pannexin1–TRPV4 Channel Signaling
Author(s) -
Daneva Zdravka,
Ottolini Matteo,
Chen YenLin,
Isakson Brant,
Sonkusare Swapnil
Publication year - 2021
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.2021.35.s1.02309
Subject(s) - trpv4 , apyrase , pannexin , pulmonary hypertension , transient receptor potential channel , pulmonary artery , medicine , chemistry , endocrinology , receptor , intracellular , gap junction , biochemistry , connexin
Endothelial cells (EC) dilate small pulmonary arteries (PAs) and lower the resting pulmonary arterial pressure (PAP). Moreover, the loss of endothelial function is a key contributor to elevated PAP in pulmonary hypertension. Therefore, an in‐depth understanding of endothelial mechanisms controlling PAP is necessary for designing novel therapeutic strategies against pulmonary hypertension. Pannexin 1 (Panx1), an ATP efflux pathway on the EC membranes, has emerged as a crucial controller of endothelial function. However, the impact of endothelial Panx1 (Panx1 EC ) on PA contractility and PAP is not known. Recent studies support the idea that endothelial transient receptor potential vanilloid 4 (TRPV4 EC ) channels dilate small PAs, and are activated by extracellular ATP (eATP). Since Panx1 EC is an ATP efflux pathway, we hypothesized that Panx1 EC ‐TRPV4 EC channel signaling dilates PAs and lowers resting PAP. Right ventricular systolic pressure (RVSP), an indirect indicator of PAP, was higher in inducible, EC‐specific Panx1 (Panx1 EC ‐/‐ ) and TRPV4 channel knockout (TRPV4 EC ‐/‐ ) mice compared to the respective control mice. The activity of TRPV4 EC channels was recorded as individual Ca 2+ influx signals (TRPV4 EC sparklets) in fluo 4‐loaded en face PAs using spinning disk confocal imaging. The TRPV4 EC sparklet activity was lower in PAs from Panx1 EC ‐/‐ mice than the control mice, identifying Panx1 EC as a novel promoter of TRPV4 EC channel activity. Apyrase (10 U/mL), an ATP hydrolyzing enzyme, also reduced the activity of TRPV4 EC sparklets in PAs from control mice but not Panx1 EC ‐/‐ mice. Pressurized PAs (15 mm Hg) from Panx1 EC ‐/‐ and TRPV4 EC ‐/‐ mice showed higher constriction to thromboxane A2 receptor agonist U46619 (1‐300 nM) compared to PAs from the respective control mice. These data indicated that Panx1 EC ‐eATP‐TRPV4 EC signaling lowers PA contractility and PAP. Consistent with previous findings that eATP dilates PAs via purinergic P2Y2 receptor (P2Y2R) signaling, ATP activation of TRPV4 EC channels was lost in PAs from inducible P2Y2 EC ‐/‐ mice. Together, these data identify a novel Panx1 EC ‐eATP‐P2Y2R EC signaling pathway that promotes TRPV4 EC channel activity in PAs. Panx1, P2Y2R, and TRPV4 channels have been shown to localize with the scaffolding protein caveolin 1 (Cav‐1), raising the possibility that Cav‐1 EC may provide a signaling scaffold for Panx1 EC ‐P2Y2R EC ‐TRPV4 EC signaling in PAs. Accordingly, P2Y2R EC ‐activation of TRPV4 EC channels was lost in PAs from inducible Cav‐1 EC ‐/‐ mice, and these mice showed higher resting RVSPs compared to the control mice. Additionally, in situ proximity ligation assay confirmed the nanometer proximity of Cav‐1 EC with Panx1 EC , P2Y2R EC , and TRPV4 EC channel in PAs. Overall, our findings identify Cav‐1 EC ‐dependent Panx1 EC ‐P2Y2R EC ‐TRPV4 EC channel pathway that dilates PAs and lowers PAP. Targeting individual elements of this pathway may provide novel therapeutic options in pulmonary vascular disorders.