title: Monocyte 15-lipoxygenase gene expression requires ERK1/2 MAPK activity.
abstract: IL-13 induces profound expression of 15-lipoxygenase (15-LO) in primary human monocytes. Our studies have defined the functional IL-13R complex, association of Jaks with the receptor components, and the tyrosine phosphorylation of several Stat molecules in response to IL-13. Furthermore, we identified both p38MAPK and protein kinase Cδ as critical regulators of 15-LO expression. In this study, we report an ERK1/2-dependent signaling cascade that regulates IL-13-mediated 15-LO gene expression. We show the rapid phosphorylation/activation of ERK1/2 upon IL-13 exposure. Our results indicate that Tyk2 kinase is required for the activation of ERK1/2, which is independent of the Jak2, p38MAPK, and protein kinase Cδ pathways, suggesting bifurcating parallel regulatory pathways downstream of the receptor. To investigate the signaling mechanisms associated with the ERK1/2-dependent expression of 15-LO, we explored the involvement of transcription factors, with predicted binding sites in the 15-LO promoter, in this process including Elk1, early growth response-1 (Egr-1), and CREB. Our findings indicate that IL-13 induces Egr-1 nuclear accumulation and CREB serine phosphorylation and that both are markedly attenuated by inhibition of ERK1/2 activity. We further show that ERK1/2 activity is required for both Egr-1 and CREB DNA binding to their cognate sequences identified within the 15-LO promoter. Furthermore, by transfecting monocytes with the decoy oligodeoxyribonucleotides specific for Egr-1 and CREB, we discovered that Egr-1 and CREB are directly involved in regulating 15-LO gene expression. These studies characterize an important regulatory role for ERK1/2 in mediating IL-13-induced monocyte 15-LO expression via the transcription factors Egr-1 and CREB.
authors.affiliation: Department of Cell Biology, Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44195, USA.
authors.forename: Ashish
authors.initials: A
authors.lastname: Bhattacharjee
authors.forename: Anny
authors.initials: A
authors.lastname: Mulya
authors.forename: Srabani
authors.initials: S
authors.lastname: Pal
authors.forename: Biswajit
authors.initials: B
authors.lastname: Roy
authors.forename: Gerald M
authors.initials: GM
authors.lastname: Feldman
authors.forename: Martha K
authors.initials: MK
authors.lastname: Cathcart
mesh_terms: D001093:Arachidonate 15-Lipoxygenase / Q000096:biosynthesis* / Q000276:immunology; D050882:CREB-Binding Protein; D004277:DNA, Single-Stranded; D004789:Enzyme Activation / Q000276:immunology; D004797:Enzyme-Linked Immunosorbent Assay; D015870:Gene Expression; D005786:Gene Expression Regulation / Q000276:immunology*; D006801:Humans; D015151:Immunoblotting; D047468:Immunoprecipitation; D018793:Interleukin-13 / Q000276:immunology / Q000378:metabolism; D019950:Mitogen-Activated Protein Kinase 1 / Q000276:immunology / Q000378:metabolism*; D048052:Mitogen-Activated Protein Kinase 3 / Q000276:immunology / Q000378:metabolism*; D009000:Monocytes / Q000201:enzymology* / Q000276:immunology; D010766:Phosphorylation; D011401:Promoter Regions, Genetic; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction / Q000276:immunology; D014162:Transfection
chemical_list: C400152:DNA enzyme ED5; D004277:DNA, Single-Stranded; D018793:Interleukin-13; D001093:Arachidonate 15-Lipoxygenase; D050882:CREB-Binding Protein; C535150:MAPK1 protein, human; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3