P2X₇ nucleotide receptor activation enhances IFNγ‐induced type II nitric oxide synthase activity in BV‐2 microglial cells

Abstract

Under normal and pathological conditions, brain cells release nucleotides that regulate a wide range of cellular responses due to activation of P2 nucleotide receptors. In this study, the effect of extracellular nucleotides on IFNc-induced NO release in murine BV-2 microglial cells was investigated. BV-2 cells expressed mRNA for metabotropic P2Y and ionotropic P2X receptors. Among the P2 receptor agonists tested, ATP, ADP, 2¢,3¢-O-(4-benzoylbenzoyl)-ATP (BzATP), and 2-methylthio-ATP (2-MeSATP), but not UTP, enhanced IFNc-induced iNOS expression and NO production, suggesting that the uridine nucleotide receptors P2Y 2 and P2Y 6 are not involved in this response. U0126, an antagonist for MEK1/2, a kinase that phosphorylates the extracellular signal-regulated kinases ERK1/2, decreased IFNc-induced NO production. BzATP, a potent P2X 7 receptor agonist, was more effective than ATP, ADP, or 2-MeSATP at enhancing IFNc-induced ERK1/2 phosphorylation. Consistent with activation of the P2X 7 receptor, periodate-oxidized ATP, a P2X 7 receptor antagonist, and suramin, a non-specific P2 receptor antagonist, inhibited the effect of ATP or BzATP on IFNc-induced NO production, whereas pyridoxal-phosphate-6-azophenyl-2¢,4¢-disulfonic acid (PPADS), an antagonist of several P2X receptor subtypes, was ineffective. These results suggest that activation of P2X 7 receptors may contribute to inflammatory responses in microglial cells seen in neurodegenerative diseases.

The role of the P2X7 receptor in murine cutaneous leishmaniasis: aspects of inflammation and parasite control

“…In addition, P2X7 receptor activation by ATP potentiated IFNγ-induced NO production in microglia [35]. Similarly, we observed a reduction in NO and ROS production in peritoneal macrophages from P2X7 KO mice compared to WT mice, suggesting an inefficient innate immune response in the inflammatory environment of P2X7 KO mice (unpublished data).…”

The cytokine IL‐1β transiently enhances P2X7 receptor expression and function in human astrocytes

“…In astrocytes, binding of BzATP has been linked to several cell-signaling pathways including ERK1 and 2 and p38 MAP kinase (Gendron et al, 2003b), as well as the transcriptional complexes AP-1 (Panenka et al, 2001) and NF-κB (Ferrari et al, 1997). BzATP has also been shown to enhance IL-1β-induced activation of NF-κB and AP-1 (John et al, 2001;Panenka et al, 2001).…”

“…Extracellular nucleotides have been shown to increase IL-1β activation of the transcription factors AP-1 and NF-κB, which would be expected to enhance activation of NOS2 (Ferrari et al, 1997;John et al, 2001). Indeed, blockade of purinergic receptors with oATP has been shown to decrease macrophage production of NO in response to lipopolysaccharide (Hu et al, 1998), and more recently it has been demonstrated that BzATP can enhance production of NO induced by IFN-γ in a microglial cell line (Gendron et al, 2003b). Given the above effects of BzATP, we examined the impact of P2X 7 R activation on NOS2 induction (Fig.…”

Exacerbation of Experimental Autoimmune Encephalomyelitis in P2X7R−/− Mice: Evidence for Loss of Apoptotic Activity in Lymphocytes

“…It has also been implicated in the activation and maturation of T cells (10,11), the formation of giant cells (12,13), the killing of invading microorganisms in macrophages (14 -16), the activation of the inducible form of NO synthase (17,18), and the shedding of L-selectin (CD62L) (19,20), an adhesion molecule that functions in leukocyte binding to the activated endothelium and in lymphocyte homing to high endothelial venules.…”