Locally formed Peroxynitrite inhibits endothelial TRPV4 channels and elevates blood pressure in obesity

Abstract

Impaired endothelium‐dependent vasodilation is a hallmark finding of obesity‐induced hypertension. Recognition that Ca2+ signaling in endothelial cells promotes vasodilation has led to the hypothesis that endothelial Ca2+ signaling is compromised during obesity, but the underlying abnormality is unknown. Here, we show that Ca2+ influx through TRPV4 channels at myoendothelial projections (MEPs) to smooth muscle cells lowers resting blood pressure in non‐obese mice, a response that is diminished in obese mice. Counter‐intuitively, release of nitric oxide (NO) from endothelial cells attenuates TRPV4 channel activity and TRPV4‐mediated vasodilation in the obese animals. Increased activities of iNOS and NOX1 correlated with elevated levels of NO and superoxide radicals at the MEPs in obese mice, ultimately reacting to form peroxynitrite. Subsequent findings revealed that peroxynitrite causes cysteine oxidation of the regulatory protein AKAP150 to inhibit TRPV4 channel activity at the MEPs. TRPV4 channel activity and vasodilation are also impaired in the arteries from obese patients, and are restored by strategies that lower peroxynitrite levels. These data suggest that defective TRPV4 channel–mediated vasodilation may contribute to obesity‐induced hypertension, and imply that inhibiting peroxynitrite may represent a strategy to normalize endothelial TRPV4 channel activity, vasodilation and blood pressure during obesity. Support or Funding Information HL121484‐01, HL138496

Mechanisms underlying selective coupling of endothelial Ca2+ signals with eNOS vs. IK/SK channels in systemic and pulmonary arteries

“…The present study advances our understanding of heterogeneity in endothelial vasodilatory pathways via three main findings: (i) TRPV4 EC channels control the basal diameter of resistance PAs and MAs; (ii) although functional IK/SK channels and eNOS are present in ECs from both PAs and MAs, TRPV4 EC channels preferentially activate eNOS in PAs and IK/SK channels in MAs; and (iii) spatial proximity of TRPV4 EC channels with IK/SK channels or eNOS and that of eNOS with Hbα determines the vasodilatory target activated by TRPV4 EC channels. Moreover, the dilatory effect of TRPV4 EC channels on baseline diameter may underlie the higher resting blood pressure in TRPV4 EC −/− mice (Ottolini et al 2020). Distinct factors regulate systemic and pulmonary arterial pressures; therefore, understanding the different mechanisms that control endothelial function in systemic and pulmonary microcirculations is a crucial first step in achieving selective regulation of one vs. the other.…”

“…Additionally, many cardiovascular disorders have been associated with selective impairment mice). TRPV4 antibody has previously been validated using TRPV4 EC −/− mice (Ottolini et al 2020). C, percentage of MEPs localized with immunofluorescence (n = 6; one-way ANOVA).…”

“…; Diamondback Drugs, Scottsdale, AZ, USA) followed by decapitation for harvesting intestinal and lung tissues. TRPV4 EC −/− mice were developed and validated as described earlier (Ottolini et al 2020). Briefly, TRPV4 fl/fl (obtained from Dr Wolfgang Liedtke, Duke University School of Medicine, Durham, NC, USA) (Moore et al 2013) were crossed with tamoxifen-inducible VE-Cadherin (Cdh5) Cre mice (Sorensen et al 2009).…”

“…DAPI immunostaining was imaged by exciting at 409 nm and collecting the emitted fluorescence with a 447/60 nm band-pass filter. The specificity of the antibody was determined using arteries from endothelial TRPV4 −/knockout mice (Ottolini et al 2020) and global eNOS −/− mice for TRPV4 and eNOS, respectively. Blocking peptides were used in antibody control experiments for IK channel (REQVNSMVDISKMHMILYDL; Genscript USA Inc., Piscataway, NJ, USA), SK channel (ETQMENYDKHVTYNAERS, Genscript USA Inc.) and Hbα (Abcam PLC., ab93083) antibodies.…”

“…The TRP vanilloid 4 (TRPV4) channel has emerged as an important Ca 2+ -influx pathway in ECs from systemic and pulmonary resistance arteries (Bagher et al 2012;Sonkusare et al 2014;Marziano et al 2017;Hong et al 2018). Pharmacological activation of endothelial TRPV4 (TRPV4 EC ) channels is known to dilate systemic and pulmonary arteries (Sonkusare et al 2012;Marziano et al 2017) and knockout of these channels specifically in the endothelium increases resting blood pressure (Ottolini et al 2020). However, whether TRPV4 EC channels control resting vascular diameter has not been addressed.…”