Lysophosphatidylcholine sensitizes TRPV2 by indirect mechanisms

Abstract

The ion channel TRPV2 has multiple roles in immunology, cancer, cardiovascular function and pain signaling. However, only few endogenous modulators of TRPV2 have been described. The phospholipase A2 (PLA2)-derived lipid lysophosphatidylcholine (LPC) was demonstrated to induce pain and itch by activating sensory neurons, and it seems to be a direct agonist of TRPV4 and TRPC5. Although LPC was suggested to modulate TRPV2, the molecular mechanisms for this effect remain unclear. Here we used patch clamp and calcium imaging techniques to investigate if and how TRPV2 is modulated by LPC. Rat, mouse and human TRPV2 were not directly activated by LPC. Instead, 10 µM LPC induced a TRPV2-independent calcium influx and irreversible inward currents in HEK 293T cells. However, 3 µM LPC induced a reversible potentiation of membrane currents induced by 2-APB, cannabidiol (CBD), probenecid (PBC) and weak acids, but not to heat. This sensitization of TRPV2 was robust in whole cell experiments, but not in cell-free inside-out or outside-out patches. A disruption of the actin cytoskeleton with cytochalasin D, but also the depletion of cholesterol or sphingomyelin from the cell membrane diminished the potentiating effects of LPC on TRPV2. In conclusion, we present novel data describing that the PLA2 downstream signaling lipid LPC amplifies TRPV2-mediated responses via indirect mechanisms that seem to involve a destabilization of lipid rafts and the actin cytoskeleton.

Keywords: Cytoskeleton; Lipid raft; Lysophosphatidylcholine; Mechanosensation; TRPV2.