In:
The Journal of Neuroscience, Society for Neuroscience, Vol. 28, No. 48 ( 2008-11-26), p. 12938-12945
Abstract:
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.
Type of Medium:
Online Resource
ISSN:
0270-6474
,
1529-2401
DOI:
10.1523/JNEUROSCI.3038-08.2008
Language:
English
Publisher:
Society for Neuroscience
Publication Date:
2008
detail.hit.zdb_id:
1475274-8
SSG:
12
