title: A critical role of the transcription factor fli-1 in murine lupus development by regulation of interleukin-6 expression.
abstract: OBJECTIVE
  The Fli-1 transcription factor is implicated in the pathogenesis of systemic lupus erythematosus (SLE), both in humans and in animal models. Dysregulation of interleukin-6 (IL-6) is also associated with SLE. The purpose of this study was to investigate whether Fli-1 directly regulates the expression of IL-6.
  
  
  METHODS
  Sera were collected from wild-type and Fli-1-heterozygous (Fli-1(+/-) ) MRL/lpr mice, and the concentration of IL-6 was measured by enzyme-linked immunosorbent assay (ELISA). Expression of IL-6 in the kidney was measured by real-time polymerase chain reaction analysis. T cells were isolated from wild-type and Fli-1(+/-) MRL/lpr mice and stimulated with CD3/CD28 beads, and the concentration of IL-6 in the supernatants was measured by ELISA. MS1 endothelial cells were transfected with Fli-1 and control small interfering RNA, and the production of IL-6 was compared after lipopolysaccharide stimulation. A chromatin immunoprecipitation (ChIP) assay was performed to determine whether Fli-1 binds to the IL-6 promoter region. Transient transfections with the NIH3T3 cell line were performed to examine whether Fli-1 regulates the expression of IL-6.
  
  
  RESULTS
  Fli-1(+/-) MRL/lpr mice had significantly decreased IL-6 levels in sera and reduced expression of IL-6 in kidneys as compared to their wild-type littermates. T cells isolated from Fli-1(+/-) MRL/lpr mice produced less IL-6 than did those from wild-type mice. Inhibiting the expression of Fli-1 in endothelial cells resulted in reduced production of IL-6. The ChIP assay revealed direct binding of Fli-1 to 3 regions within the IL-6 promoter. Fli-1 activated transcription from the IL-6 promoter in a dose-dependent manner.
  
  
  CONCLUSIONS
  The direct regulation of IL-6 expression by Fli-1 represents one possible mechanism for the protective effect of decreased Fli-1 expression in lupus.
authors.affiliation: Medical University of South Carolina, Charleston.
authors.forename: Shuzo
authors.initials: S
authors.lastname: Sato
authors.forename: Mara
authors.initials: M
authors.lastname: Lennard Richard
authors.forename: Danielle
authors.initials: D
authors.lastname: Brandon
authors.forename: Joy N
authors.initials: JN
authors.lastname: Jones Buie
authors.forename: Jim C
authors.initials: JC
authors.lastname: Oates
authors.forename: Gary S
authors.initials: GS
authors.lastname: Gilkeson
authors.forename: Xian K
authors.initials: XK
authors.lastname: Zhang
mesh_terms: D000818:Animals; D001323:Autoantibodies; D047369:Chromatin Immunoprecipitation; D004195:Disease Models, Animal; D004797:Enzyme-Linked Immunosorbent Assay; D005786:Gene Expression Regulation; D006579:Heterozygote; D015850:Interleukin-6 / Q000235:genetics* / Q000276:immunology / Q000378:metabolism; D007668:Kidney / Q000378:metabolism; D008070:Lipopolysaccharides; D008180:Lupus Erythematosus, Systemic / Q000235:genetics* / Q000276:immunology / Q000378:metabolism; D051379:Mice; D019463:Mice, Inbred MRL lpr; D041681:NIH 3T3 Cells; D011401:Promoter Regions, Genetic; D051789:Proto-Oncogene Protein c-fli-1 / Q000235:genetics* / Q000276:immunology / Q000378:metabolism; D012333:RNA, Messenger / Q000032:analysis*; D060888:Real-Time Polymerase Chain Reaction; D013601:T-Lymphocytes / Q000378:metabolism*
chemical_list: D001323:Autoantibodies; C497426:Fli1 protein, mouse; D015850:Interleukin-6; D008070:Lipopolysaccharides; D051789:Proto-Oncogene Protein c-fli-1; D012333:RNA, Messenger