TRPV4-mediated endothelial Ca²⁺ influx and vasodilation in response to shear stress

Abstract

The transient receptor potential vallinoid type 4 (TRPV4) channel has been implicated in the endothelial shear response and flow-mediated dilation, although the precise functions of this channel remain poorly understood. In the present study, we investigated the role of TRPV4 in shear stress-induced endothelial Ca(2+) entry and the potential link between this signaling response and relaxation of small resistance arteries. Using immunohistochemical analysis and RT-PCR, we detected strong expression of TRPV4 protein and mRNA in the endothelium in situ and endothelial cells freshly isolated from mouse small mesenteric arteries. The selective TRPV4 agonist GSK1016790A increased endothelial Ca(2+) and induced potent relaxation of small mesenteric arteries from wild-type (WT) but not TRPV4(-/-) mice. Luminal flow elicited endothelium-dependent relaxations that involved both nitric oxide and EDHFs. Both nitric oxide and EDHF components of flow-mediated relaxation were markedly reduced in TRPV4(-/-) mice compared with WT controls. Using a fura-2/Mn(2+) quenching assay, shear was observed to produce rapid Ca(2+) influx in endothelial cells, which was markedly inhibited by the TRPV4 channel blocker ruthenium red and TRPV4-specific short interfering RNA. Flow elicited a similar TRPV4-mediated Ca(2+) entry in HEK-293 cells transfected with TRPV4 channels but not in nontransfected cells. Collectively, these data indicate that TRPV4 may be a potential candidate of mechanosensitive channels in endothelial cells through which the shear stimulus is transduced into Ca(2+) signaling, leading to the release of endothelial relaxing factors and flow-mediated dilation of small resistance arteries.

Nitric Oxide–Dependent Feedback Loop Regulates Transient Receptor Potential Vanilloid 4 (TRPV4) Channel Cooperativity and Endothelial Function in Small Pulmonary Arteries

“…ATP can be released from sympathetic nerves during synaptic transmission, or can be released into the circulation by ECs, SMCs, or erythrocytes 25, 26, 64, 65. Shear stress, which is a well‐known activator of endothelial TRPV4 channels,66, 67, 68 also induces the release of ATP,65 suggesting a possible involvement of P2 purinergic receptor‐TRPV4 signaling in flow‐induced vasodilation. Endothelial Gq‐protein coupled receptor agonists carbachol and bradykinin activated TRPV4 channels through a phospholipase C‐diacylglycerol‐protein kinase C mechanism in MAs 5.…”

Low intravascular pressure activates endothelial cell TRPV4 channels, local Ca 2+ events, and IK Ca channels, reducing arteriolar tone

“…ECs contain a range of different TRP channels (21), and in resistance arteries, TRPV4 channels are intimately involved in vasodilation to EC-dependent agonists (22,23) and shear stress-induced dilation (24). Sustained activation to low pressure is a unique addition to this list.…”

Update on vascular endothelial Ca2+signalling: A tale of ion channels, pumps and transporters

“…Unlike the Ca 2+ response to extracellular ligands, mechanosensitive Ca 2+ signals normally lack the biphasic kinetics and exhibit either a transient [20,21] or an oscillatory pattern [21][22][23][24][25] . In a few cases, a dose-dependent stepwise elevation in [Ca 2+ ]i was observed in cultured ECs exposed to laminar shear stress [24,26,27] . The contact between air microbubbles and cultured ECs may also result in an intracellular Ca 2+ wave [28] .…”

“…TRPC3-and TRPC6-induced Ca 2+ inflow underpin the stimulatory effect of VEGF on endothelial proliferation, migration and permeability [18,231,236] , while ATP exploits TRPC3 to activate NF-κB and increase vascular cell adhesion molecule-1 expression [237] . TRPC3-driven NO synthesis and vasore- TRPV1 TRPV2 TRPV3 TRPV4 TRPV5 TRPV6 PCa/PNa and conductance (pS) [202] 10, 35-80 1-3, NM 12, 172 6, 90 > 100, 75 > 100, 40-70 Human coronary artery ECs [300] (+RT-PCR, WB, IHC) Human pulmonary artery ECs [415] +(RT-PCR) +(RT-PCR) +(RT-PCR) Human pulmonary microvascular ECs +(RT-PCR) Human cerebral microvascular ECs [272] +(RT-PCR, IC) Human cerebral arterioles ECs [305] +(RT-PCR, IHC) Human dermal microvascular ECs [319] +(RT-PCR, WB) Breast cancer derived microvascular ECs [319] +(RT-PCR, WB) Human umbilical vein ECs [227,277,296,301] +(RT-PCR) +(WB, IHC) Mouse aortic ECs [280,285,299,306] +(WB) +(RT-PCR, WB, NM, IHC) Mouse pulmonary artery ECs [313] +(WB, IHC) Mouse mesenteric artery ECs [27,280,302] +(RT-PCR, WB, IC) +(RT-PCR, IC) Mouse cerebral microvascular ECs +(RT-PCR) +(RT-PCR, WB) +(RT-PCR) Mouse dermal microvascular ECs [307] +(RT-PCR, WB) Mouse carotid artery ECs [290,296] +(IHC) Rat mesenteric artery ECs [226,275,302] +(WB) +(WB, IC, IHC) Rat femoral artery ECs [312] +(RT-PCR, IC) Rat pulmonary artery ECs [303] +(WB, IHC) Rat renal artery ECs [303] +(IHC) Rat cardiac microvascular ECs [303,…”

“…Recent work proposed that Cav-1 governs TRPV4 activity and location to the plasma membrane in ECs [301] . NO, PGI2, and IKCa/SKCa/MaxiKmediated EDHF are vasodilatory pathways that are activated following by pharmacological activation of TRPV4 [27,291,[302][303][304] . An alternative mechanism has been unravelled in human coronary arterioles from patients with coronary artery disease, where flow-induced TRPV4 activation causes ECs to release mitochondrial ROS, thereby relaxing the adjoining VSMCs [300] .…”