title: CCR1-mediated STAT3 tyrosine phosphorylation and CXCL8 expression in THP-1 macrophage-like cells involve pertussis toxin-insensitive Gα(14/16) signaling and IL-6 release.
abstract: Agonists of CCR1 contribute to hypersensitivity reactions and atherosclerotic lesions, possibly via the regulation of the transcription factor STAT3. CCR1 was demonstrated to use pertussis toxin-insensitive Gα(14/16) to stimulate phospholipase Cβ and NF-κB, whereas both Gα(14) and Gα(16) are also capable of activating STAT3. The coexpression of CCR1 and Gα(14/16) in human THP-1 macrophage-like cells suggests that CCR1 may use Gα(14/16) to induce STAT3 activation. In this study, we demonstrated that a CCR1 agonist, leukotactin-1 (CCL15), could indeed stimulate STAT3 Tyr(705) and Ser(727) phosphorylation via pertussis toxin-insensitive G proteins in PMA-differentiated THP-1 cells, human erythroleukemia cells, and HEK293 cells overexpressing CCR1 and Gα(14/16). The STAT3 Tyr(705) and Ser(727) phosphorylations were independent of each other and temporally distinct. Subcellular fractionation and confocal microscopy illustrated that Tyr(705)-phosphorylated STAT3 translocated to the nucleus, whereas Ser(727)-phosphorylated STAT3 was retained in the cytosol after CCR1/Gα(14) activation. CCL15 was capable of inducing IL-6 and IL-8 (CXCL8) production in both THP-1 macrophage-like cells and HEK293 cells overexpressing CCR1 and Gα(14/16). Neutralizing Ab to IL-6 inhibited CCL15-mediated STAT3 Tyr(705) phosphorylation, whereas inhibition of STAT3 activity abolished CCL15-activated CXCL8 release. The ability of CCR1 to signal through Gα(14/16) provides a linkage for CCL15 to regulate IL-6/STAT3-signaling cascades, leading to expression of CXCL8, a cytokine that is involved in inflammation and the rupture of atherosclerotic plaque.
authors.affiliation: Division of Life Science, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China.
authors.forename: Maggie M K
authors.initials: MM
authors.lastname: Lee
authors.forename: Ricky K S
authors.initials: RK
authors.lastname: Chui
authors.forename: Issan Y S
authors.initials: IY
authors.lastname: Tam
authors.forename: Alaster H Y
authors.initials: AH
authors.lastname: Lau
authors.forename: Yung H
authors.initials: YH
authors.lastname: Wong
mesh_terms: D000906:Antibodies / Q000494:pharmacology; D002467:Cell Nucleus / Q000187:drug effects / Q000235:genetics / Q000276:immunology; D019742:Chemokines, CC / Q000276:immunology / Q000494:pharmacology; D003600:Cytosol / Q000187:drug effects / Q000276:immunology; D043802:GTP-Binding Protein alpha Subunits, Gq-G11 / Q000235:genetics / Q000276:immunology*; D015870:Gene Expression / Q000187:drug effects / Q000276:immunology; D057809:HEK293 Cells; D006801:Humans; D015850:Interleukin-6 / Q000276:immunology*; D016209:Interleukin-8 / Q000096:biosynthesis / Q000276:immunology*; D020014:K562 Cells; D019402:Macrophage Inflammatory Proteins / Q000276:immunology / Q000494:pharmacology; D008264:Macrophages / Q000166:cytology / Q000187:drug effects / Q000276:immunology*; D037342:Pertussis Toxin / Q000494:pharmacology; D010766:Phosphorylation; D010957:Plasmids; D020033:Protein Isoforms / Q000235:genetics / Q000276:immunology; D054389:Receptors, CCR1 / Q000819:agonists / Q000235:genetics / Q000276:immunology*; D050796:STAT3 Transcription Factor / Q000235:genetics / Q000276:immunology*; D012694:Serine / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D014162:Transfection; D014443:Tyrosine / Q000378:metabolism; D000093242:Interleukin-6 Inhibitors
chemical_list: D000906:Antibodies; D019742:Chemokines, CC; D043802:GTP-Binding Protein alpha Subunits, Gq-G11; D015850:Interleukin-6; D016209:Interleukin-8; D019402:Macrophage Inflammatory Proteins; D037342:Pertussis Toxin; D020033:Protein Isoforms; D054389:Receptors, CCR1; D050796:STAT3 Transcription Factor; D012694:Serine; D014443:Tyrosine; D000093242:Interleukin-6 Inhibitors; C108814:CCL15 protein, human; C515300:CCR1 protein, human; C508600:IL6 protein, human; C494086:STAT3 protein, human; C119109:GNA14 protein, human