title: K(+) regulates Ca(2+) to drive inflammasome signaling: dynamic visualization of ion flux in live cells.
abstract: P2X7 purinergic receptor engagement with extracellular ATP induces transmembrane potassium and calcium flux resulting in assembly of the NLRP3 inflammasome in LPS-primed macrophages. The role of potassium and calcium in inflammasome regulation is not well understood, largely due to limitations in existing methods for interrogating potassium in real time. The use of KS6, a novel sensor for selective and sensitive dynamic visualization of intracellular potassium flux in live cells, multiplexed with the intracellular calcium sensor Fluo-4, revealed a coordinated relationship between potassium and calcium. Interestingly, the mitochondrial potassium pool was mobilized in a P2X7 signaling, and ATP dose-dependent manner, suggesting a role for mitochondrial sensing of cytosolic ion perturbation. Through treatment with extracellular potassium we found that potassium efflux was necessary to permit sustained calcium entry, but not transient calcium flux from intracellular stores. Further, intracellular calcium chelation with BAPTA-AM indicated that P2X7-induced potassium depletion was independent of calcium mobilization. This evidence suggests that both potassium efflux and calcium influx are necessary for mitochondrial reactive oxygen generation upstream of NLRP3 inflammasome assembly and pyroptotic cell death. We propose a model wherein potassium efflux is necessary for calcium influx, resulting in mitochondrial reactive oxygen generation to trigger the NLRP3 inflammasome.
authors.affiliation: Center for Biosignatures Discovery Automation, The Biodesign Institute, Arizona State University, Tempe, 85287 AZ, USA.|Biological Design Graduate Program, School of Biological and Health Systems Engineering, Ira A. Fulton Schools of Engineering, Arizona State University, Tempe, 85287 AZ, USA.
authors.forename: J R
authors.initials: JR
authors.lastname: Yaron
authors.affiliation: Center for Biosignatures Discovery Automation, The Biodesign Institute, Arizona State University, Tempe, 85287 AZ, USA.
authors.forename: S
authors.initials: S
authors.lastname: Gangaraju
authors.affiliation: Center for Biosignatures Discovery Automation, The Biodesign Institute, Arizona State University, Tempe, 85287 AZ, USA.
authors.forename: M Y
authors.initials: MY
authors.lastname: Rao
authors.affiliation: Center for Biosignatures Discovery Automation, The Biodesign Institute, Arizona State University, Tempe, 85287 AZ, USA.
authors.forename: X
authors.initials: X
authors.lastname: Kong
authors.affiliation: Center for Biosignatures Discovery Automation, The Biodesign Institute, Arizona State University, Tempe, 85287 AZ, USA.
authors.forename: L
authors.initials: L
authors.lastname: Zhang
authors.affiliation: Center for Biosignatures Discovery Automation, The Biodesign Institute, Arizona State University, Tempe, 85287 AZ, USA.
authors.forename: F
authors.initials: F
authors.lastname: Su
authors.affiliation: Center for Biosignatures Discovery Automation, The Biodesign Institute, Arizona State University, Tempe, 85287 AZ, USA.
authors.forename: Y
authors.initials: Y
authors.lastname: Tian
authors.affiliation: Center for Biosignatures Discovery Automation, The Biodesign Institute, Arizona State University, Tempe, 85287 AZ, USA.
authors.forename: H L
authors.initials: HL
authors.lastname: Glenn
authors.affiliation: Center for Biosignatures Discovery Automation, The Biodesign Institute, Arizona State University, Tempe, 85287 AZ, USA.
authors.forename: D R
authors.initials: DR
authors.lastname: Meldrum
mesh_terms: D000255:Adenosine Triphosphate / Q000494:pharmacology; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D020013:Calcium Signaling; D002460:Cell Line; D058847:Inflammasomes / Q000378:metabolism*; D008264:Macrophages / Q000378:metabolism; D051379:Mice; D008928:Mitochondria / Q000378:metabolism; D008954:Models, Biological; D011188:Potassium / Q000378:metabolism*; D017382:Reactive Oxygen Species / Q000378:metabolism; D058486:Receptors, Purinergic P2X7 / Q000378:metabolism / Q000502:physiology
chemical_list: D058847:Inflammasomes; D017382:Reactive Oxygen Species; D058486:Receptors, Purinergic P2X7; D000255:Adenosine Triphosphate; D011188:Potassium; D002118:Calcium