The P2X7 receptor forms a dye-permeable pore independent of its intracellular domain but dependent on membrane lipid composition

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Abstract

The P2X7 receptor mediates extracellular-ATP signaling implicated in the development of devastating diseases such as chronic pain and cancer. Activation of the P2X7 receptor leads to opening of the characteristic dye-permeable membrane pore for molecules up to ~900 Da. However, it remains controversial what constitutes this peculiar pore and how it opens. Here we show that the panda P2X7 receptor, when purified and reconstituted into liposomes, forms an intrinsic dye-permeable pore in the absence of other cellular components. Unexpectedly, we found that this pore opens independent of its unique C-terminal domain. We also found that P2X7 channel activity is facilitated by phosphatidylglycerol and sphingomyelin, but dominantly inhibited by cholesterol through direct interactions with the transmembrane domain. In combination with cell-based functional studies, our data suggest that the P2X7 receptor itself constitutes a lipid-composition dependent dye-permeable pore, whose opening is facilitated by palmitoylated cysteines near the pore-lining helix.

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Akira Karasawa

Department of Molecular Medicine, Cornell University, Ithaca, United States

Competing interests
The authors declare that no competing interests exist.
Kevin Michalski

Department of Molecular Medicine, Cornell University, Ithaca, United States

Competing interests
The authors declare that no competing interests exist.
Polina Mikhelzon

Department of Molecular Medicine, Cornell University, Ithaca, United States

For correspondence
pm542@cornell.edu

Competing interests
The authors declare that no competing interests exist.
Toshimitsu Kawate

Department of Molecular Medicine, Cornell University, Ithaca, United States

For correspondence
tk499@cornell.edu

Competing interests
The authors declare that no competing interests exist.

"This ORCID iD identifies the author of this article:" 0000-0002-5005-2031

Funding

National Institutes of Health (GM114379)

Toshimitsu Kawate

The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.

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This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.