Gene transcription of fgl2 in endothelial cells is controlled by Ets-1 and Oct-1 and requires the presence of both Sp1 and Sp3.
The immune coagulant fgl2/fibroleukin has been previously shown to play a pivotal role in the pathogenesis of murine and human fulminant hepatitis and fetal loss syndrome. Constitutive expression of fgl2 transcripts at low levels are seen in cytotoxic T cells, endothelial, intestinal and trophoblast cells, while specific factors (such as virus and cytokines) are required to induce high levels of fgl2 expression in other cell types including monocytes/macrophages. To address the transcriptional mechanisms that regulate constitutive expression of fgl2, murine genomic clones were characterized and the transcription start site was defined by 5'-RACE and primer extension. A comprehensive assessment of basal fgl2 promoter activity in murine vascular endothelial cells defined a minimal 119 bp region responsible for constitutive fgl2 transcription. A complex positive regulatory domain (PRD) spanning a 39-bp sequence from -87 to -49 (relative to the transcription start site) was identified. Electrophoretic mobility shift assay studies in vascular endothelial cells revealed that the nucleoprotein complexes that form on this positive regulatory domain (PRD) contain Sp1/Sp3 family members, Oct-1, and Ets-1. Heterologous expression studies in Drosophila Schneider cells confirmed that the constitutive expression of this gene is controlled by Ets-1 and requires the presence both of the Sp1 and Sp3 transcription factors. The presence of this complex multicomponent PRD in the fgl2 proximal promoter is consistent with the observation that, in vivo, fgl2 expression is tightly regulated. Moreover, viral induced fgl2 expression also requires the presence of this PRD. These results clearly demonstrate that multiple cis DNA elements in a clustered region work cooperatively to regulate constitutive fgl2 expression and interact with inducible elements to regulate viral-induced fgl2 expression in endothelial cells.
Liu
Mingfeng
M
Multi Organ Transplant Program, Toronto General Hospital and The University of Toronto, Canada.
Leibowitz
Julian L
JL
Clark
David A
DA
Mendicino
Michael
M
Ning
Qin
Q
Ding
Jin Wen
JW
D'Abreo
Cheryl
C
Fung
Laisum
L
Marsden
Philip A
PA
Levy
Gary A
GA
D000818:Animals; D001483:Base Sequence; D004247:DNA / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000378:metabolism*; D004730:Endothelium, Vascular / Q000166:cytology / Q000378:metabolism*; D005340:Fibrinogen / Q000378:metabolism*; D017353:Gene Deletion; D005786:Gene Expression Regulation; D051863:Host Cell Factor C1; D008156:Luciferases / Q000378:metabolism; D051379:Mice; D008807:Mice, Inbred BALB C; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D009154:Mutation; D050811:Octamer Transcription Factor-1; D010957:Plasmids / Q000378:metabolism; D011401:Promoter Regions, Genetic; D050784:Proto-Oncogene Protein c-ets-1; D011518:Proto-Oncogene Proteins / Q000378:metabolism*; D050783:Proto-Oncogene Proteins c-ets; D012333:RNA, Messenger / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017422:Sequence Analysis, DNA; D016329:Sp1 Transcription Factor / Q000378:metabolism*; D051705:Sp3 Transcription Factor; D014157:Transcription Factors / Q000378:metabolism*; D014158:Transcription, Genetic; D014162:Transfection
D004268:DNA-Binding Proteins; C494041:ETS1 protein, human; C494042:Ets1 protein, mouse; C490637:Fgl2 protein, mouse; C497693:Hcfc1 protein, mouse; D051863:Host Cell Factor C1; D050811:Octamer Transcription Factor-1; C494166:Pou2f1 protein, mouse; D050784:Proto-Oncogene Protein c-ets-1; D011518:Proto-Oncogene Proteins; D050783:Proto-Oncogene Proteins c-ets; D012333:RNA, Messenger; D016329:Sp1 Transcription Factor; C497122:Sp3 protein, mouse; D014157:Transcription Factors; D051705:Sp3 Transcription Factor; D005340:Fibrinogen; D004247:DNA; D008156:Luciferases