title: The Fli-1 transcription factor is a critical regulator for controlling the expression of chemokine C-X-C motif ligand 2 (CXCL2).
abstract: Mammalian cells produce inflammatory cytokines and chemokines in response to innate immune signals and their expression is tightly regulated. Chemokine (C-X-C motif) ligand 2 (CXCL2), also known as macrophage inflammatory protein 2-alpha (MIP2-alpha), is an inflammatory chemokine belonging to the CXC chemokine family. CXCL2 is chemotactic for neutrophils and elevated expression of CXCL2 is associated with many inflammatory and autoimmune diseases. The Fli-1 gene belongs to the large Ets transcription factor family, whose members regulate a wide variety of cellular functions including the immune response. In this study, we demonstrate that endothelial cells transfected with Fli-1 specific siRNA produce significantly less CXCL2 compared to cells transfected with control siRNA after stimulation by the Toll-like receptor (TLR) 4 ligands, lipopolysaccharide (LPS) and tumor necrosis factor alpha (TNF-α). The production of CXCL2 in endothelial cells stimulated with LPS stimulation is dose-dependent. We found that Fli-1 binds to the CXCL2 promoter as established by Chromatin immunoprecipitation‎ (ChIP) assay. Transient transfection assays show that Fli-1 drives transcription from the CXCL2 promoter in a dose-dependent manner and Fli-1 regulates the expression of CXCL2 largely by directly binding to the promoter. Targeted knockdown and transient transfection experiments suggest that both Fli-1 and the p65 subunit of NF-κB affect the activation of CXCL2 in an additive manner. These results indicate that Fli-1 is a novel, critical transcription factor that regulates the expression of the inflammatory chemokine CXCL2.
authors.affiliation: Jinan Central Hospital, Shandong University, Jinan, Shangdong, China; Department of Medicine, Division of Rheumatology & Immunology, Medical University of South Carolina, Charleston, SC 29425, United States.
authors.forename: Ning
authors.initials: N
authors.lastname: Lou
authors.affiliation: Department of Medicine, Division of Rheumatology & Immunology, Medical University of South Carolina, Charleston, SC 29425, United States.
authors.forename: Mara L
authors.initials: ML
authors.lastname: Lennard Richard
authors.affiliation: Department of Regenerative Medicine and Cell Biology, Medical University of South Carolina, Charleston, SC 29425, United States.
authors.forename: Jin
authors.initials: J
authors.lastname: Yu
authors.affiliation: Department of Regenerative Medicine and Cell Biology, Medical University of South Carolina, Charleston, SC 29425, United States.
authors.forename: Mark
authors.initials: M
authors.lastname: Kindy
authors.affiliation: Department of Medicine, Division of Rheumatology & Immunology, Medical University of South Carolina, Charleston, SC 29425, United States. Electronic address: zhangjo@musc.edu.
authors.forename: Xian K
authors.initials: XK
authors.lastname: Zhang
mesh_terms: D000818:Animals; D054426:Chemokine CXCL2 / Q000096:biosynthesis*; D047369:Chromatin Immunoprecipitation; D042783:Endothelial Cells / Q000276:immunology / Q000378:metabolism*; D004797:Enzyme-Linked Immunosorbent Assay; D005786:Gene Expression Regulation / Q000502:physiology*; D055785:Gene Knockdown Techniques; D006801:Humans; D015151:Immunoblotting; D051379:Mice; D051789:Proto-Oncogene Protein c-fli-1 / Q000276:immunology / Q000378:metabolism*; D060888:Real-Time Polymerase Chain Reaction
chemical_list: D054426:Chemokine CXCL2; D051789:Proto-Oncogene Protein c-fli-1
keywords: CXCL2; Chemokine; Inflammation; Lipopolysaccharide (LPS); Toll-like receptor (TLR); Transcription factor Fli-1