P2X4 assembles with P2X7 and pannexin-1 in gingival epithelial cells and modulates ATP-induced reactive oxygen species production and inflammasome activation.
We have previously reported that Porphyromonas gingivalis infection of gingival epithelial cells (GEC) requires an exogenous danger signal such as ATP to activate an inflammasome and caspase-1, thereby inducing secretion of interleukin (IL)-1β. Stimulation with extracellular ATP also stimulates production of reactive oxygen species (ROS) in GEC. However, the mechanism by which ROS is generated in response to ATP, and the role that different purinergic receptors may play in inflammasome activation, is still unclear. In this study, we revealed that the purinergic receptor P2X(4) is assembled with the receptor P2X(7) and its associated pore, pannexin-1. ATP induces ROS production through a complex consisting of the P2X(4), P2X(7), and pannexin-1. P2X(7)-mediated ROS production can activate the NLRP3 inflammasome and caspase-1. Furthermore, separate depletion or inhibition of P2X(4), P2X(7), or pannexin-1 complex blocks IL-1β secretion in P. gingivalis-infected GEC following ATP treatment. However, activation via P2X(4) alone induces ROS generation but not inflammasome activation. These results suggest that ROS is generated through stimulation of a P2X(4)/P2X(7)/pannexin-1 complex, and reveal an unexpected role for P2X(4), which acts as a positive regulator of inflammasome activation during microbial infection.
Department of Molecular Cell Biology, University of California Merced, Merced, California, United States of America.
Shu-Chen
SC
Hung
Chul Hee
CH
Choi
Najwane
N
Said-Sadier
Larry
L
Johnson
Kalina Rosenova
KR
Atanasova
Hanen
H
Sellami
Özlem
Ö
Yilmaz
David M
DM
Ojcius
D000255:Adenosine Triphosphate / Q000494:pharmacology*; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism; D002460:Cell Line; D017630:Connexins / Q000037:antagonists & inhibitors / Q000235:genetics* / Q000378:metabolism; D004847:Epithelial Cells / Q000187:drug effects* / Q000276:immunology / Q000382:microbiology; D005786:Gene Expression Regulation; D005881:Gingiva / Q000187:drug effects* / Q000276:immunology / Q000382:microbiology; D006801:Humans; D058847:Inflammasomes / Q000187:drug effects* / Q000276:immunology / Q000378:metabolism; D053583:Interleukin-1beta / Q000096:biosynthesis / Q000276:immunology; D015603:Keratinocytes / Q000187:drug effects / Q000276:immunology / Q000382:microbiology; D000071199:NLR Family, Pyrin Domain-Containing 3 Protein; D009419:Nerve Tissue Proteins / Q000037:antagonists & inhibitors / Q000235:genetics* / Q000378:metabolism; D016966:Porphyromonas gingivalis / Q000254:growth & development / Q000276:immunology; D061251:Primary Cell Culture; D011485:Protein Binding; D034741:RNA, Small Interfering / Q000235:genetics / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000819:agonists* / Q000378:metabolism; D058848:Receptors, Purinergic P2X4 / Q000235:genetics* / Q000378:metabolism; D058486:Receptors, Purinergic P2X7 / Q000235:genetics* / Q000378:metabolism; D015398:Signal Transduction
D002352:Carrier Proteins; D017630:Connexins; D058847:Inflammasomes; D053583:Interleukin-1beta; D000071199:NLR Family, Pyrin Domain-Containing 3 Protein; C453881:NLRP3 protein, human; D009419:Nerve Tissue Proteins; C492764:PANX1 protein, human; D034741:RNA, Small Interfering; D017382:Reactive Oxygen Species; D058848:Receptors, Purinergic P2X4; D058486:Receptors, Purinergic P2X7; D000255:Adenosine Triphosphate