Extracellular ATP activates transcription factor NF-kappaB through the P2Z purinoreceptor by selectively targeting NF-kappaB p65.
Cells of the macrophage lineage express a peculiar surface receptor for extracellular ATP, designated P2Z/P2X7 purinergic receptor, that induces pore formation and collapse of the plasma membrane potential. Although the function of the P2Z receptor is largely unknown, accumulating evidence implicates its role in cell signaling and immune reactions. Here, we investigated the effect of P2Z receptor ligation on the activation of NF-kappaB, a transcription factor controlling cytokine expression and apoptosis. Exposure of microglial cells to ATP but not other nucleotides resulted in potent NF-kappaB activation. This effect was specifically mediated by the P2Z receptor, because selective receptor antagonists prevented NF-kappaB activation. NF-kappaB activation required reactive oxygen intermediates and proteases of the caspase family, because it was abolished by antioxidants and specific protease inhibitors. The subunit composition of the ATP-induced NF- kappaB-DNA complex was rather unusual. Whereas exposure to LPS-induced prototypical NF-kappaB p50 homo- and p65 (RelA)/p50 heterodimers, ATP stimulation resulted in the sole appearance of a p65 homodimer. This is the first demonstration that a certain stimulus activates a particular NF-kappaB subunit. Because different NF-kappaB complexes exhibit distinct transcriptional and DNA-binding activities, ATP may control the expression of a subset of NF-kappaB target genes distinct from those activated by classical proinflammatory mediators.
Ferrari
D
D
Department of Internal Medicine I, Medical Clinics, Eberhard-Karls-University, D-72076 Tübingen, Germany.
Wesselborg
S
S
Bauer
M K
MK
Schulze-Osthoff
K
K
D000255:Adenosine Triphosphate / Q000494:pharmacology*; D000818:Animals; D020170:Caspase 1; D002460:Cell Line; D003546:Cysteine Endopeptidases / Q000378:metabolism; D005786:Gene Expression Regulation; D007375:Interleukin-1 / Q000378:metabolism; D007700:Kinetics; D051379:Mice; D017628:Microglia / Q000187:drug effects / Q000378:metabolism*; D009097:Multienzyme Complexes / Q000378:metabolism; D016328:NF-kappa B / Q000378:metabolism*; D046988:Proteasome Endopeptidase Complex; D017382:Reactive Oxygen Species / Q000378:metabolism; D018048:Receptors, Purinergic P2 / Q000378:metabolism*; D058486:Receptors, Purinergic P2X7; D015398:Signal Transduction; D051996:Transcription Factor RelA; D015533:Transcriptional Activation; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism
D007375:Interleukin-1; D009097:Multienzyme Complexes; D016328:NF-kappa B; C546469:P2rx7 protein, mouse; D017382:Reactive Oxygen Species; D018048:Receptors, Purinergic P2; D058486:Receptors, Purinergic P2X7; D051996:Transcription Factor RelA; D014409:Tumor Necrosis Factor-alpha; D000255:Adenosine Triphosphate; D003546:Cysteine Endopeptidases; D020170:Caspase 1; D046988:Proteasome Endopeptidase Complex