FasL-triggered death of Jurkat cells requires caspase 8-induced, ATP-dependent cross-talk between Fas and the purinergic receptor P2X(7).
Fas ligation via the ligand FasL activates the caspase-8/caspase-3-dependent extrinsic death pathway. In so-called type II cells, an additional mechanism involving tBid-mediated caspase-9 activation is required to efficiently trigger cell death. Other pathways linking FasL-Fas interaction to activation of the intrinsic cell death pathway remain unknown. However, ATP release and subsequent activation of purinergic P2X(7) receptors (P2X(7)Rs) favors cell death in some cells. Here, we evaluated the possibility that ATP release downstream of caspase-8 via pannexin1 hemichannels (Panx1 HCs) and subsequent activation of P2X(7)Rs participate in FasL-stimulated cell death. Indeed, upon FasL stimulation, ATP was released from Jurkat cells in a time- and caspase-8-dependent manner. Fas and Panx1 HCs colocalized and inhibition of the latter, but not connexin hemichannels, reduced FasL-induced ATP release. Extracellular apyrase, which hydrolyzes ATP, reduced FasL-induced death. Also, oxidized-ATP or Brilliant Blue G, two P2X(7)R blockers, reduced FasL-induced caspase-9 activation and cell death. These results represent the first evidence indicating that the two death receptors, Fas and P2X(7)R connect functionally via caspase-8 and Panx1 HC-mediated ATP release to promote caspase-9/caspase-3-dependent cell death in lymphoid cells. Thus, a hitherto unsuspected route was uncovered connecting the extrinsic to the intrinsic pathway to amplify death signals emanating from the Fas receptor in type II cells.
Centro de Estudios Moleculares de la Célula, Universidad de Chile, Santiago, Chile.
Adam
A
Aguirre
Kenji F
KF
Shoji
Juan C
JC
Sáez
Mauricio
M
Henríquez
Andrew F G
AF
Quest
D000255:Adenosine Triphosphate / Q000031:analogs & derivatives / Q000494:pharmacology / Q000502:physiology*; D017209:Apoptosis; D001081:Apyrase / Q000502:physiology; D053148:Caspase 3 / Q000502:physiology; D053181:Caspase 8 / Q000502:physiology*; D053453:Caspase 9 / Q000502:physiology; D017630:Connexins / Q000502:physiology; D053222:Fas Ligand Protein / Q000502:physiology*; D006801:Humans; D019169:Jurkat Cells; D009419:Nerve Tissue Proteins / Q000502:physiology; D058920:Purinergic P2X Receptor Antagonists / Q000494:pharmacology; D058486:Receptors, Purinergic P2X7 / Q000502:physiology*; D012394:Rosaniline Dyes / Q000494:pharmacology; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology; D019014:fas Receptor / Q000502:physiology
D017630:Connexins; C505661:FASLG protein, human; D053222:Fas Ligand Protein; D009419:Nerve Tissue Proteins; C492764:PANX1 protein, human; D058920:Purinergic P2X Receptor Antagonists; D058486:Receptors, Purinergic P2X7; D012394:Rosaniline Dyes; D019014:fas Receptor; C017199:2',3'-dialdehyde ATP; D000255:Adenosine Triphosphate; C505407:CASP3 protein, human; C505530:CASP8 protein, human; C506433:CASP9 protein, human; D053148:Caspase 3; D053181:Caspase 8; D053453:Caspase 9; D001081:Apyrase; C004692:coomassie Brilliant Blue