title: IL-10 synergistically enhances GM-CSF-induced CCR1 expression in myelomonocytic cells.
abstract: CC chemokine receptor 1 (CCR1) has been implicated in inflammation. The present study examined the signaling mechanisms that mediate GM-CSF/IL-10-induced synergistic CCR1 protein expression in monocytic U937 cells. GM-CSF alone markedly increased both the mRNA and protein expression of CCR1. IL-10 augmented GM-CSF-induced CCR1 protein expression with no effect on mRNA expression. PD098059 and U0126 (two MEK inhibitors), and LY294002 (a PI3K inhibitor) inhibited GM-CSF/IL-10-induced CCR1 gene and protein expression. PD098059, U0126, and LY294002 also attenuated chemotaxis of GM-CSF/IL-10-primed U937 cells in response to MIP-1alpha. Immunoblotting studies show that GM-CSF alone induced ERK2 phosphorylation; whereas, IL-10 alone induced p70(S6k) phosphorylation in U937 cells. Neither cytokine when used alone induced PKB/Akt phosphorylation. Combined GM-CSF/IL-10 treatment of U937 cells induced phosphorylation of ERK2, p70(S6k), and PKB/Akt. PD098059 and U0126 completely abrogated ERK2 phosphorylation; whereas, LY294002 completely blocked PKB/Akt and p70(S6k) phosphorylation. Our findings indicate that IL-10 may potentiate GM-CSF-induced CCR1 protein expression in U937 cells via activation of PKB/Akt and p70(S6k).
authors.affiliation: Department of Pharmacology, Faculty of Medicine, National University of Singapore, Singapore, Singapore.
authors.forename: Hui
authors.initials: H
authors.lastname: Li
authors.forename: Wai
authors.initials: W
authors.lastname: Cheung
authors.forename: Hui Hwa
authors.initials: HH
authors.lastname: Choo
authors.forename: Jasmine H P
authors.initials: JH
authors.lastname: Chan
authors.forename: Poh San
authors.initials: PS
authors.lastname: Lai
authors.forename: W S
authors.initials: WS
authors.lastname: Fred Wong
mesh_terms: D054405:Chemokine CCL3; D054407:Chemokine CCL4; D002634:Chemotaxis, Leukocyte; D004357:Drug Synergism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005786:Gene Expression Regulation; D016178:Granulocyte-Macrophage Colony-Stimulating Factor / Q000494:pharmacology*; D006801:Humans; D016753:Interleukin-10 / Q000494:pharmacology*; D019402:Macrophage Inflammatory Proteins / Q000494:pharmacology; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D009000:Monocytes / Q000187:drug effects / Q000276:immunology*; D022423:Myeloid Cells / Q000187:drug effects / Q000276:immunology; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt; D012333:RNA, Messenger / Q000096:biosynthesis; D054389:Receptors, CCR1; D019707:Receptors, Chemokine / Q000096:biosynthesis* / Q000235:genetics; D038762:Ribosomal Protein S6 Kinases, 70-kDa / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D020298:U937 Cells
chemical_list: C515300:CCR1 protein, human; D054405:Chemokine CCL3; D054407:Chemokine CCL4; D004791:Enzyme Inhibitors; D019402:Macrophage Inflammatory Proteins; D011518:Proto-Oncogene Proteins; D012333:RNA, Messenger; D054389:Receptors, CCR1; D019707:Receptors, Chemokine; D016753:Interleukin-10; D016178:Granulocyte-Macrophage Colony-Stimulating Factor; C494918:AKT1 protein, human; D017346:Protein Serine-Threonine Kinases; D051057:Proto-Oncogene Proteins c-akt; D038762:Ribosomal Protein S6 Kinases, 70-kDa; D020928:Mitogen-Activated Protein Kinases