Transient receptor potential vanilloid 4 (TRPV4) activation by arachidonic acid requires protein kinase A–mediated phosphorylation

Abstract

Transient receptor potential vanilloid 4 (TRPV4) is a Ca-permeable channel of the transient receptor potential (TRP) superfamily activated by diverse stimuli, including warm temperature, mechanical forces, and lipid mediators such as arachidonic acid (AA) and its metabolites. This activation is tightly regulated by protein phosphorylation carried out by various serine/threonine or tyrosine kinases. It remains poorly understood how phosphorylation differentially regulates TRPV4 activation in response to different stimuli. We investigated how TRPV4 activation by AA, an important signaling process in the dilation of coronary arterioles, is affected by protein kinase A (PKA)-mediated phosphorylation at Ser-824. Wildtype and mutant TRPV4 channels were expressed in human coronary artery endothelial cells (HCAECs). AA-induced TRPV4 activation was blunted in the S824A mutant but was enhanced in the phosphomimetic S824E mutant, whereas the channel activation by the synthetic agonist GSK1016790A was not affected. The low level of basal phosphorylation at Ser-824 was robustly increased by the redox signaling molecule hydrogen peroxide (HO). The HO-induced phosphorylation was accompanied by an enhanced channel activation by AA, and this enhanced response was largely abolished by PKA inhibition or S824A mutation. We further identified a potential structural context dependence of Ser-824 phosphorylation-mediated TRPV4 regulation involving an interplay between AA binding and the possible phosphorylation-induced rearrangements of the C-terminal helix bearing Ser-824. These results provide insight into how phosphorylation specifically regulates TRPV4 activation. Redox-mediated TRPV4 phosphorylation may contribute to pathologies associated with enhanced TRPV4 activity in endothelial and other systems.

Vasoconstrictor Mechanisms in Chronic Hypoxia-Induced Pulmonary Hypertension: Role of Oxidant Signaling

“…This process is facilitated by the scaffolding molecule CD36 that brings Fyn and TRPV4 together for efficient phosphorylation [ 231 ]. The possible phosphorylation site of TRPV4 that mediates its activation by H 2 O 2 is serine 824 residue as demonstrated in human coronary artery endothelial cells channels [ 232 ]. Moreover, increased basal Ca 2+ levels in PAECs from PAH rats are normalized by the SOD memetic TEMPOL, by mitochondria-targeted antioxidant MitoQ and by TRPV4 inhibitors [ 113 ], suggesting TRPV4 opening is maintained by endogenous ROS from mitochondria.…”

TRPV4 channel opening mediates pressure-induced pancreatitis initiated by Piezo1 activation

“…However, the mechanism by which physical stimuli activate PLA2 is not known. Phosphorylation of PKA and PKC increases the sensitization of TRPV4 (44,45); therefore, it is possible that activation of TRPV4 through AA may require PKA or PKC phosphorylation (44).…”

Epoxy fatty acid dysregulation and neuroinflammation in Alzheimer’s disease is resolved by a soluble epoxide hydrolase inhibitor

“…This leads to diminished levels of EETs and EDPs and their anti-inflammatory activities on both astrocytes and microglia. Although no defined receptors have been identified for EETs, TRPV4 and G-proteins have been implicated in neuroinflammatory pathways downstream of EETs(35,36). Besides the astrocytes, sEH is known to be highly expressed in the vasculature where it mediates vascular inflammation and barrier function through both EETs and EDPs(21,37).…”