title: IL-6 production is positively regulated by two distinct Src homology domain 2-containing tyrosine phosphatase-1 (SHP-1)-dependent CCAAT/enhancer-binding protein β and NF-κB pathways and an SHP-1-independent NF-κB pathway in lipopolysaccharide-stimulated bone marrow-derived macrophages.
abstract: Comparison of the inflammatory cytokine profile in bone marrow-derived macrophages (BMDMs) from normal and Src homology domain 2-containing tyrosine phosphatase-1 (SHP-1)-deficient Motheaten (me/me) mice revealed a dramatic suppression of IL-6 transcript and protein in me/me BMDMs after LPS stimulation. Interfering with SHP-1 expression using antisense SHP-1 oligonucleotides led to a significant downregulation of IL-6 in normal BMDMs. Conversely, reconstitution of me/me BMDMs with the SHP-1 gene using adenoviral vectors restored IL-6 production. Expression of only SHP-1 Src homology region 2 domains in normal BMDMs inhibited IL-6 production, confirming that IL-6 regulation depends on SHP-1 phosphatase activity. We further demonstrated that loss of SHP-1 function affects proper phosphorylation of Erk1/2 MAPKs and, to a lesser degree, of NF-κB downstream of TLR4 in BMDMs. Inefficient phosphorylation of Erk1/2 MAPKs abrogated the activation of C/EBPβ transcription factor, which was reversed on restoration of SHP-1 function and led to a concomitant enhancement of IL-6 production. We demonstrate that IL-6 production is regulated by a complex network of signaling pathways that include SHP-1-dependent activation of Erk1/2-C/EBPβ and NF-κB, in addition to SHP-1-independent IκB pathway through the activation of protein tyrosine kinases downstream of TLR4. Taken together, these results revealed for the first time, to our knowledge, a positive and critical role of SHP-1 in IL-6 regulation and dependence of Erk1/2-C/EBPβ pathway in addition to that of IκB on SHP-1 activity required for IL-6 induction after LPS stimulation.
authors.affiliation: Department of Biochemistry, Microbiology and Immunology, Faculty of Medicine, University of Ottawa, Ottawa, Ontario KIH 8M5, Canada.
authors.forename: Dorothy
authors.initials: D
authors.lastname: Rego
authors.forename: Ashok
authors.initials: A
authors.lastname: Kumar
authors.forename: Ladan
authors.initials: L
authors.lastname: Nilchi
authors.forename: Kathryn
authors.initials: K
authors.lastname: Wright
authors.forename: Stephen
authors.initials: S
authors.lastname: Huang
authors.forename: Maya
authors.initials: M
authors.lastname: Kozlowski
mesh_terms: D000818:Animals; D015153:Blotting, Western; D001854:Bone Marrow Cells / Q000276:immunology / Q000378:metabolism; D022782:CCAAT-Enhancer-Binding Protein-beta / Q000276:immunology / Q000378:metabolism*; D002469:Cell Separation; D016207:Cytokines / Q000096:biosynthesis; D024202:Electrophoretic Mobility Shift Assay; D004797:Enzyme-Linked Immunosorbent Assay; D005434:Flow Cytometry; D015870:Gene Expression; D020869:Gene Expression Profiling; D005786:Gene Expression Regulation / Q000276:immunology*; D015850:Interleukin-6 / Q000096:biosynthesis* / Q000235:genetics / Q000276:immunology; D008070:Lipopolysaccharides / Q000276:immunology; D008264:Macrophages / Q000276:immunology* / Q000378:metabolism; D051379:Mice; D008817:Mice, Mutant Strains; D016328:NF-kappa B / Q000276:immunology / Q000378:metabolism*; D020411:Oligonucleotide Array Sequence Analysis; D053824:Protein Tyrosine Phosphatase, Non-Receptor Type 6 / Q000276:immunology / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction / Q000276:immunology; D015854:Up-Regulation
chemical_list: D022782:CCAAT-Enhancer-Binding Protein-beta; D016207:Cytokines; D015850:Interleukin-6; D008070:Lipopolysaccharides; D016328:NF-kappa B; D053824:Protein Tyrosine Phosphatase, Non-Receptor Type 6; C509248:Ptpn6 protein, mouse