Modes of action of lysophospholipids as endogenous activators of the TRPV4 ion channel.

The Transient Receptor Potential Vanilloid 4 (TRPV4) channel has been shown to function in many physiological and pathophysiological processes. Despite abundant information on its importance in physiology, very few endogenous agonists for this channel have been described, and very few underlying mechanisms for its activation have been clarified. TRPV4 is expressed by several types of cells, such as vascular endothelial and skin and lung epithelial cells, where it plays pivotal roles in their function. In the present study, we show that TRPV4 is activated by lysophosphatidic acid (LPA) in both endogenous and heterologous expression systems, pinpointing this molecule as one of the few known endogenous agonists for TRPV4. Importantly, LPA is a bioactive glycerophospholipid, relevant in several physiological conditions, including inflammation and vascular function, where TRPV4 has also been found to be essential. Here we also provide mechanistic details of the activation of TRPV4 by LPA and another glycerophospholipid, lysophosphatidylcholine or LPC, and show that LPA directly interacts with both the N- and C-terminal regions of TRPV4 to activate this channel. Moreover, we show that LPC activates TRPV4 by producing an open state with a different single-channel conductance to that observed with LPA. Our data suggest that the activation of TRPV4 can be finely tuned in response to different endogenous lipids, highlighting this phenomenon as a regulator of cell and organismal physiology. Abstract figure legend TRPV4 is differentially activated by distinct ligands. Lysophosphatidic acid 18:1 (LPA 18:1) activates TRPV4 with a larger conductance as compared to lysophosphatidylcholine 18:1 (LPC18:1). These different modes of activation can lead to differences in cell excitability. This article is protected by copyright. All rights reserved.