Structural determinants of 5′,6′-epoxyeicosatrienoic acid binding to and activation of TRPV4 channel

Abstract

TRPV4 cation channel activation by cytochrome P450-mediated derivatives of arachidonic acid (AA), epoxyeicosatrienoic acids (EETs), constitute a major mechanisms of endothelium-derived vasodilatation. Besides, TRPV4 mechano/osmosensitivity depends on phospholipase A2 (PLA2) activation and subsequent production of AA and EETs. However, the lack of evidence for a direct interaction of EETs with TRPV4 together with claims of EET-independent mechanical activation of TRPV4 has cast doubts on the validity of this mechanism. We now report: 1) The identification of an EET-binding pocket that specifically mediates TRPV4 activation by 5′,6′-EET, AA and hypotonic cell swelling, thereby suggesting that all these stimuli shared a common structural target within the TRPV4 channel; and 2) A structural insight into the gating of TRPV4 by a natural agonist (5′,6′-EET) in which K535 plays a crucial role, as mutant TRPV4-K535A losses binding of and gating by EET, without affecting GSK1016790A, 4α-phorbol 12,13-didecanoate and heat mediated channel activation. Together, our data demonstrates that the mechano- and osmotransducing messenger EET gates TRPV4 by a direct action on a site formed by residues from the S2-S3 linker, S4 and S4-S5 linker.

Calcium influx through TRPV4 channels modulates the adherens contacts between retinal microvascular endothelial cells

“…; Berna‐Erro et al . ). The differences in TRPV4 expression in cells that form the inner and outer BRB (MVECs and HCECs) are consistent with the heterogeneity of TRPV4 signalling across dissimilar vascular beds (Maishan et al .…”

TRPV4—A Missing Link Between Mechanosensation and Immunity

“…Such localized indirect activation is proposed to cause highly compartmentalized TRPV4-mediated Ca 2+ signaling at focal adhesions and facilitates downstream activation of additional β 1 -integrins (integrin-to-integrin signaling) and leads to cell reorientation (40,41). Moreover, several studies have shown that TRPV4 activation in response to osmotic or mechanical stress depends on formation of intracellular mechanomessengers, like lipid metabolites as arachidonic acid and its derivative 5 ′ ,6 ′epoxyeicosatrienoic acid, and PIP 2 (21,(42)(43)(44)(45). Additionally, calmodulin as a classical second messenger binds to TRPV4 and mediates Ca 2+ influx by conformational change and dissociation of its N-and C-terminus (20).…”

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

“…Although the synthetic agonist 4␣-PDD activates TRPV4 by directly binding to its TM3 and TM4 segments in a ligand-like manner (38), earlier studies indicate that AA-induced TRPV4 activation involves metabolism of AA by cytochrome P450 into 5,6-epoxyeicosatrienoic acid (5,6-EET) (34,35,39). A recent study has further proposed a potential 5,6-EET-binding site in TRPV4, which is formed by residues from the TM2-TM3 linker, TM4, and TM4-TM5 linker (65). However, other studies indicate that TRPV4 can also be activated by other EET regioisomers such as 11,12-EET (66, 67), AA (36,68), and endocannabinoids such as 2-arachidonoylglycerol (37).…”