NF-κB transcriptional activation by TNFα requires phospholipase C, extracellular signal-regulated kinase 2 and poly(ADP-ribose) polymerase-1

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dc.contributor.author Vuong, Billy
dc.contributor.author Hogan-Cann, Adam D J
dc.contributor.author Alano, Conrad C
dc.contributor.author Stevenson, Mackenzie
dc.contributor.author Chan, Wai Y
dc.contributor.author Anderson, Christopher M
dc.contributor.author Swanson, Raymond A
dc.contributor.author Kauppinen, Tiina M
dc.date.accessioned 2015-12-09T14:57:56Z
dc.date.available 2015-12-09T14:57:56Z
dc.date.issued 2015-12-04
dc.identifier.citation Journal of Neuroinflammation. 2015 Dec 04;12(1):229
dc.identifier.uri http://dx.doi.org/10.1186/s12974-015-0448-8
dc.identifier.uri http://hdl.handle.net/1993/30970
dc.description.abstract Abstract Background The nuclear enzyme poly(ADP-ribose) polymerase-1 (PARP-1) is required for pro-inflammatory effects of TNFα. Our previous studies demonstrated that PARP-1 mediates TNFα-induced NF-κB activation in glia. Here, we evaluated the mechanisms by which TNFα activates PARP-1 and PARP-1 mediates NF-κB activation. Methods Primary cultures of mouse cortical astrocytes and microglia were treated with TNFα and suitable signaling pathway modulators (pharmacological and molecular). Outcome measures included calcium imaging, PARP-1 activation status, NF-κB transcriptional activity, DNA damage assesment and cytokine relesease profiling. Results TNFα induces PARP-1 activation in the absence of detectable DNA strand breaks, as measured by the PANT assay. TNFα-induced transcriptional activation of NF-κB requires PARP-1 enzymatic activity. Enzymatic activation of PARP-1 by TNFα was blocked in Ca2+-free medium, by Ca2+ chelation with BAPTA-AM, and by D609, an inhibitor of phoshatidyl choline-specific phospholipase C (PC-PLC), but not by thapsigargin or by U73112, an inhibitor of phosphatidyl inisitol-specific PLC (PI -PLC). A TNFR1 blocking antibody reduced Ca2+ influx and PARP-1 activation. TNFα-induced PARP-1 activation was also blocked by siRNA downregulation of ERK2 and by PD98059, an inhibitor of the MEK / ERK protein kinase cascade. Moreover, TNFα-induced NF-κB (p65) transcriptional activation was absent in cells expressing PARP-1 that lacked ERK2 phosphorylation sites, while basal NF-κB transcriptional activation increased in cells expressing PARP-1 with a phosphomimetic substitution at an ERK2 phophorylation site. Conclusions These results suggest that TNFα induces PARP-1 activation through a signaling pathway involving TNFR1, Ca2+ influx, activation of PC-PLC, and activation of the MEK1 / ERK2 protein kinase cascade. TNFα-induced PARP-1 activation is not associated with DNA damage, but ERK2 mediated phosphorylation of PARP-1.
dc.title NF-κB transcriptional activation by TNFα requires phospholipase C, extracellular signal-regulated kinase 2 and poly(ADP-ribose) polymerase-1
dc.type Journal Article
dc.language.rfc3066 en
dc.rights.holder Vuong et al.
dc.date.updated 2015-12-08T20:18:47Z

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