title: Atypical lambda/iota PKC conveys 5-lipoxygenase/leukotriene B4-mediated cross-talk between phospholipase A2s regulating NF-kappa B activation in response to tumor necrosis factor-alpha and interleukin-1beta.
abstract: The transcription factor nuclear factor kappaB (NF-kappaB) plays crucial roles in a wide variety of biological functions such as inflammation, stress, and immune responses. We have shown previously that secretory nonpancreatic (snp) and cytosolic (c) phospholipase A(2) (PLA(2)) regulate NF-kappaB activation in response to tumor necrosis factor (TNF)-alpha or interleukin (IL)-1beta activation and that a functional coupling mediated by the 5-lipoxygenase (5-LO) metabolite leukotriene B(4) (LTB(4)) exists between snpPLA(2) and cPLA(2) in human keratinocytes. In this study, we have further investigated the mechanisms of PLA(2)-modulated NF-kappaB activation with respect to specific kinases involved in TNF-alpha/IL-1beta-stimulated cPLA(2) phosphorylation and NF-kappaB activation. The protein kinase C (PKC) inhibitors RO 31-8220, Gö 6976, and a pseudosubstrate peptide inhibitor of atypical PKCs attenuated arachidonic acid release, cPLA(2) phosphorylation, and NF-kappaB activation induced by TNF-alpha or IL-1beta, thus indicating atypical PKCs in cPLA(2) regulation and transcription factor activation. Transfection of a kinase-inactive mutant of lambda/iotaPKC in NIH-3T3 fibroblasts completely abolished TNF-alpha/IL-1beta-stimulated cellular arachidonic acid release and cPLA(2) activation assayed in vitro, confirming the role of lambda/iotaPKC in cPLA(2) regulation. Furthermore, lambda/iotaPKC and cPLA(2) phosphorylation was attenuated by phosphatidyinositol 3-kinase (PI3-kinase) inhibitors, which also reduced NF-kappaB activation in response to TNF-alpha and IL-1beta, indicating a role for PI3-kinase in these processes in human keratinocytes. TNF-alpha- and IL-1beta-induced phosphorylation of lambda/iotaPKC was attenuated by inhibitors toward snpPLA(2) and 5-LO and by an LTB(4) receptor antagonist, suggesting lambda/iotaPKC as a downstream effector of snpPLA(2) and 5-LO/LTB(4) the LTB(4) receptor. Hence, lambda/iotaPKC regulates snpPLA(2)/LTB(4)-mediated cPLA(2) activation, cellular arachidonic acid release, and NF-kappaB activation induced by TNF-alpha and IL-1beta. In addition, our results demonstrate that PI3-kinase and lambda/iotaPKC are involved in cytokine-induced cPLA(2) and NF-kappaB activation, thus identifying lambda/iotaPKC as a novel regulator of cPLA(2).
authors.affiliation: UNIGEN Center for Molecular Biology, Faculty of Chemistry and Biology, Norwegian University of Science and Technology, N-7491 Trondheim, Norway.
authors.forename: M W
authors.initials: MW
authors.lastname: Anthonsen
authors.forename: S
authors.initials: S
authors.lastname: Andersen
authors.forename: A
authors.initials: A
authors.lastname: Solhaug
authors.forename: B
authors.initials: B
authors.lastname: Johansen
mesh_terms: D016475:3T3 Cells; D000818:Animals; D001094:Arachidonate 5-Lipoxygenase / Q000378:metabolism*; D016718:Arachidonic Acid / Q000378:metabolism; D006801:Humans; D007375:Interleukin-1 / Q000378:metabolism*; D007527:Isoenzymes / Q000378:metabolism*; D015603:Keratinocytes / Q000378:metabolism; D007975:Leukotriene B4 / Q000378:metabolism*; D051379:Mice; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D016328:NF-kappa B / Q000378:metabolism*; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D010741:Phospholipases A / Q000378:metabolism*; D010766:Phosphorylation; D011493:Protein Kinase C / Q000378:metabolism*; D020239:Receptor Cross-Talk; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism*; D048051:p38 Mitogen-Activated Protein Kinases; D000099293:Protein Kinase C-lambda
chemical_list: D001094:Arachidonate 5-Lipoxygenase; D016718:Arachidonic Acid; D007375:Interleukin-1; D007527:Isoenzymes; D007975:Leukotriene B4; D020928:Mitogen-Activated Protein Kinases; D016328:NF-kappa B; D019869:Phosphatidylinositol 3-Kinases; D010741:Phospholipases A; D011493:Protein Kinase C; D014409:Tumor Necrosis Factor-alpha; D048051:p38 Mitogen-Activated Protein Kinases; D000099293:Protein Kinase C-lambda