P2X4 Assembles with P2X7 and Pannexin-1 in Gingival Epithelial Cells and Modulates ATP-induced Reactive Oxygen Species Production and Inflammasome Activation

Shu-Chen Hung, Chul Hee Choi., Najwane Said-Sadier, Larry Johnson, Kalina Rosenova Atanasova, Hanen Sellami, O¨ zlem Yilmaz, David M. Ojcius1
Source: PLoS ONE
Publication Date: (2013)
Issue: 8(7): e70210
Research Area:
Basic Research
Cells used in publication:
Epithelial, gingival, human
Species: human
Tissue Origin:
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)-1ß. 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-1ß 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.