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Nucleotide receptor P2RX7 stimulation enhances LPS-induced interferon-β production in murine macrophages
M L Gavala1, Y-P Liu, L Y Lenertz
12.University of Wisconsin School of Medicine and Public Health, 600 Highland Ave., CSC H4/472, Madison, WI 53792-9988, USA. jsmith27@pediatrics.wisc.edu.
Abstract:
Stimulation of P2RX(7) with extracellular ATP potentiates numerous LPS-induced proinflammatory events, including cytokine induction in macrophages, but the molecular mechanisms underlying this process are not well defined. Although P2RX(7) ligation has been proposed to activate several transcription factors, many of the LPS-induced mediators affected by P2RX(7) activation are not induced by P2RX(7) agonists alone, suggesting a complementary role for P2RX(7) in transcriptional regulation. Type I IFN production, whose expression is tightly controlled by multiple transcription factors that form an enhanceosome, is critical for resistance against LPS-containing bacteria. The effect of purinergic receptor signaling on LPS-dependent type I IFN is unknown and would be of great relevance to a diverse array of inflammatory conditions. The present study demonstrates that stimulation of macrophages with P2RX(7) agonists substantially enhances LPS-induced IFN-β expression, and this enhancement is ablated in macrophages that do not express functional P2RX(7) or when the MAPK MEK1/2 pathways are inhibited. Potentiation of LPS-induced IFN-β expression following P2RX(7) stimulation is likely transcriptionally regulated, as this enhancement is observed at the IFN-β promoter level. Furthermore, P2RX(7) stimulation is able to increase the phosphorylation and subsequent IFN-β promoter occupancy of IRF-3, a transcription factor that is critical for IFN-β transcription by TLR agonists. This newly discovered role for P2RX(7) in IFN regulation may have implications in antimicrobial defense, which has been linked to P2RX(7) activation in other studies.
Insights
Stimulating the P2RX7 receptor with ATP amplifies lipopolysaccharide (LPS)-induced Type I Interferon (IFN-β) production in macrophages. This enhancement, mediated by MAPK MEK1/2 pathways and IRF-3 transcription factor, is crucial for antimicrobial defense.
Area of Science:
- Immunology
- Cellular and Molecular Biology
- Biochemistry
Background:
- Extracellular ATP binding to P2RX7 receptors potentiates LPS-induced proinflammatory events, but mechanisms remain unclear.
- P2RX7 activation complements other signaling pathways, particularly in transcriptional regulation.
- Type I Interferon (IFN-β) production is vital for combating LPS-containing bacteria.
Purpose of the Study:
- To investigate the role of P2RX7 signaling in LPS-dependent Type I IFN production.
- To elucidate the molecular mechanisms by which P2RX7 influences IFN-β expression.
- To determine the relevance of P2RX7 in inflammatory conditions and antimicrobial defense.
Main Methods:
- Stimulation of macrophages with P2RX7 agonists and lipopolysaccharide (LPS).
- Assessment of IFN-β expression and its transcriptional regulation at the promoter level.
- Inhibition of MAPK MEK1/2 pathways and analysis of IRF-3 phosphorylation and promoter occupancy.
Main Results:
- P2RX7 stimulation substantially enhanced LPS-induced IFN-β expression in macrophages.
- This enhancement was abolished in P2RX7-deficient macrophages and upon MEK1/2 pathway inhibition.
- P2RX7 activation increased IRF-3 phosphorylation and IFN-β promoter occupancy, indicating transcriptional regulation.
Conclusions:
- P2RX7 receptor signaling plays a significant role in potentiating LPS-induced Type I IFN-β production.
- The P2RX7-mediated enhancement of IFN-β is dependent on MAPK MEK1/2 pathways and IRF-3 activation.
- This finding highlights a novel role for P2RX7 in regulating IFN-β, with potential implications for antimicrobial defense and inflammatory diseases.
