Cooperative gating and sensitivity of TRPV4 channels are regulated by distinct factors (1057.8)

Abstract

TRPV4 (transient receptor vanilloid 4) sparklets represent Ca2+ influx through single TRPV4 channels (Sonkusare et.al., Science, 2012). In this study, we determined the differences in endothelial cell (EC) TRPV4 channel activity in mouse mesenteric (MA) and basilar (BA) arteries by recording TRPV4 sparklet activity in slit open, en face preparation, under physiological conditions of temperature and ionic solutions. TRPV4 channels in MAs and BAs exhibited a number of similarities, including a 4‐channel meta‐structure, the same quantal levels (0.19 ΔF/F0), and cooperative channel gating at myoendothelial projections (MEPs). However, an analysis of TRPV4 sparklets indicated that the channel open probability (Po) in response to TRPV4 agonist GSK1016790A (GSK101, 100 nM) is ~ 15‐fold lower in BAs than MAs. In agreement with the Ca2+ imaging results, the sensitivity of TRPV4 channels to the agonist GSK101, measured as currents in freshly isolated cells is shifted by ~10‐fold in cerebral arteries. The TRPV4 channel gating at MEPs was cooperative in both MAs and BAs, as indicated by similar coupling coefficients (~0.2). In MAs, the cooperative channel gating at the MEPs was dependent on a kinase anchoring protein 150 (AKAP150). Notably, AKAP150 exhibited similar clustering at MEPs in MAs and BAs. These results suggest that cooperativity and agonist sensitivity of TRPV4 channels are functionally separable.Grant Funding Source: HL044455, 1P01HL095488, R37DK053832, R01HL098243 to MTN