Phosphoinositides regulate P2X4 ATP-gated channels through direct interactions.
Journal of Neuroscience. 2008-11-26; 28(48): 12938-12945
DOI: 10.1523/jneurosci.3038-08.2008
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1. J Neurosci. 2008 Nov 26;28(48):12938-45. doi: 10.1523/JNEUROSCI.3038-08.2008.
Phosphoinositides regulate P2X4 ATP-gated channels through direct interactions.
Bernier LP(1), Ase AR, Chevallier S, Blais D, Zhao Q, Boué-Grabot E, Logothetis
D, Séguéla P.
Author information:
(1)Montreal Neurological Institute, Department of Neurology and Neurosurgery,
McGill University, Montréal, Québec, Canada H3A 2B4.
P2X receptors are ATP-gated nonselective cation channels highly permeable to
calcium that contribute to nociception and inflammatory responses. The P2X(4)
subtype, upregulated in activated microglia, is thought to play a critical role
in the development of tactile allodynia following peripheral nerve injury.
Posttranslational regulation of P2X(4) function is crucial to the cellular
mechanisms of neuropathic pain, however it remains poorly understood. Here, we
show that the phosphoinositides PI(4,5)P(2) (PIP(2)) and PI(3,4,5)P(3) (PIP(3)),
products of phosphorylation by wortmannin-sensitive phosphatidylinositol
4-kinases and phosphatidylinositol 3-kinases, can modulate the function of native
and recombinant P2X(4) receptor channels. In BV-2 microglial cells, depleting the
intracellular levels of PIP(2) and PIP(3) with wortmannin significantly decreased
P2X(4) current amplitude and P2X(4)-mediated calcium entry measured in patch
clamp recordings and ratiometric ion imaging, respectively. Wortmannin-induced
depletion of phosphoinositides in Xenopus oocytes decreased the current amplitude
of P2X(4) responses by converting ATP into a partial agonist. It also decreased
their recovery from desensitization and affected their kinetics. Injection of
phosphoinositides in wortmannin-treated oocytes reversed these effects and
application of PIP(2) on excised inside-out macropatches rescued P2X(4) currents
from rundown. Moreover, we report the direct interaction of phospholipids with
the proximal C-terminal domain of P2X(4) subunit (Cys(360)-Val(375)) using an in
vitro binding assay. These results demonstrate novel regulatory roles of the
major signaling phosphoinositides PIP(2) and PIP(3) on P2X(4) function through
direct channel-lipid interactions.
DOI: 10.1523/JNEUROSCI.3038-08.2008
PMCID: PMC2628555
PMID: 19036987 [Indexed for MEDLINE]