TRPV4-stimulation Releases ATP via Pannexin Channels in Human Pulmonary Fibroblasts

We previously described several ionic conductances in human pulmonary fibroblasts (HPFs), including one activated by two structurally distinct TRPV4-channel agonists: 4α-phorbol-12,13-didecanoate (4αPDD) and GSK1016790A. However, the TRPV4-activated current exhibited peculiar properties: it developed slowly over many minutes, exhibited reversal potentials that could vary by tens of millivolts even within a given cell, and was not easily reversed by subsequent addition of two distinct TRPV4-selective blockers (RN-1734 or HC-067047). In this study, we characterized that conductance more carefully. We show here that 4αPDD stimulated a delayed release of ATP into the extracellular space which was reduced by genetic silencing of pannexin expression, and that the 4αPDD-evoked current could be blocked by apyrase (rapidly degrades ATP) or by the P2Y purinergic receptor-channel blocker PPADS, and could be mimicked by exogenous addition of ATP. We further show the 4αPDD-evoked current to be blocked by pre-treating with RN-1734 or HC-067047, by Gd3+ or La3+, or by two distinct blockers of pannexin channels (carbenoxolone or probenecid), but not by a blocker of connexin hemi-channels (flufenamic acid). We also found expression of TRPV4- and pannexin channel proteins. 4αPDD markedly increased calcium-flashing in our cells, the latter was abrogated by the P2Y channel blocker PPADS, and the 4αPDD-evoked current was eliminated by loading the cytosol with BAPTA or by inhibiting Ca2+/calmodulin-sensitive kinase II (CamK-II) using KN93. Altogether, we interpret these findings to suggest that 4αPDD triggers ATP-release via pannexin channels, which in turn acts in an autocrine and/or paracrine fashion to stimulate PPADS-sensitive purinergic receptors on HPFs.

Jaar van publicatie:2018

BOF-keylabel:ja

IOF-keylabel:ja

BOF-publication weight:2

CSS-citation score:1

Auteurs:International

Authors from:Higher Education

Toegankelijkheid:Closed