Stimulation of P2X receptors enhances lipooligosaccharide-mediated apoptosis of endothelial cells.
Exposure of endothelial cells to lipid A-containing molecules, such as lipopolysaccharide (LPS) or lipooligosaccharide (LOS), causes the release of purinergic compounds [e.g., adenosine 5'-triphosphate (ATP)] and can lead to apoptosis. The P2X family of purinergic receptors (e.g., P2X(7)) has been reported to modulate LPS signaling events and to participate in apoptosis. We investigated the role that P2X receptors play in the apoptosis that follows exposure of bovine endothelial cells to Haemophilus somnus LOS. Addition of P2X inhibitors, such as periodate-oxidized ATP (oATP) or pyridoxal-phosphate-6-azophenyl-2',4'-disulfonic acid tetrasodium, significantly reduced LOS-induced apoptosis. Incubation of endothelial cells with apyrase, which degrades ATP, diminished LOS-induced apoptosis of endothelial cells. Concomitant addition of P2X agonists [e.g., 2',3'-(4-benzoyl)-benzoyl ATP or ATP] to LOS-treated endothelial cells significantly enhanced caspase-3 activation. The P2X antagonist oATP significantly blocked caspase-8 but not caspase-9 activation in LOS-treated endothelial cells. Together, these data indicate that stimulation of P2X receptors enhances LOS-induced apoptosis of endothelial cells, possibly as a result of endogenous release of ATP, which results in caspase-8 activation.
Sylte
Matt J
MJ
Department of Pathobiological Sciences, School of Veterinary Medicine, Madison, WI 63706, USA.
Kuckleburg
Chris J
CJ
Inzana
Thomas J
TJ
Bertics
Paul J
PJ
Czuprynski
Charles J
CJ
D000255:Adenosine Triphosphate / Q000031:analogs & derivatives* / Q000378:metabolism / Q000494:pharmacology; D000818:Animals; D000942:Antigens, Bacterial / Q000494:pharmacology*; D017209:Apoptosis; D053181:Caspase 8; D053453:Caspase 9; D020169:Caspases / Q000378:metabolism; D002417:Cattle; D042783:Endothelial Cells / Q000187:drug effects* / Q000378:metabolism; D044138:Haemophilus somnus / Q000737:chemistry; D008070:Lipopolysaccharides / Q000494:pharmacology*; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3 / Q000378:metabolism; D058910:Purinergic P2 Receptor Agonists; D058919:Purinergic P2 Receptor Antagonists; D011732:Pyridoxal Phosphate / Q000031:analogs & derivatives* / Q000494:pharmacology; D058469:Receptors, Purinergic P2X
D000942:Antigens, Bacterial; D008070:Lipopolysaccharides; D058910:Purinergic P2 Receptor Agonists; D058919:Purinergic P2 Receptor Antagonists; D058469:Receptors, Purinergic P2X; C023023:lipid-linked oligosaccharides; C004282:periodate-oxidized adenosine 5'-triphosphate; C077792:pyridoxal phosphate-6-azophenyl-2',4'-disulfonic acid; D011732:Pyridoxal Phosphate; D000255:Adenosine Triphosphate; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D053181:Caspase 8; D053453:Caspase 9; D020169:Caspases