Two members of the HNF-3 family have opposite effects on a lung transcriptional element; HNF-3 alpha stimulates and HNF-3 beta inhibits activity of region I from the Clara cell secretory protein (CCSP) promoter.
Region I of the Clara cell secretory protein (CCSP; also called CC10) promoter contains at least three functional factor binding sites, an upstream HNF-3 site and a downstream overlapping AP-1/HNF-3 site (Sawaya, P.L., Stripp, B. R., Whitsett, J.A., and Luse, D. S. Mol. Cell. Biol. (1993) 13, 3860-3871). Fragments containing -320/+58 of the rat CCSP promoter were mutagenized to eliminate one or two factor binding sites in region I, cloned into a luciferase reporter cassette, and assayed for activity by transfection into cultured lung (H441) cells. We found that the HNF-3 sites alone can account for the activity of region I in H441 cells. The activity of the two HNF-3 sites is synergistic; this effect depends on the presence of an upstream factor binding site. We had shown previously that H441 cells contain exclusively the HNF-3 alpha form of HNF-3, whereas HeLa cells have essentially no HNF-3. Co-transfection of an HNF-3 alpha expression plasmid with a CCSP reporter containing four copies of region I in HeLa cells stimulated CCSP activity 4-fold, whereas co-expression of HNF-3 beta inhibited activity 8-fold. HNF-3 beta was also inhibitory to region I expression in H441 cells, but to a lesser extent than in HeLa cells, presumably because of the high levels of HNF-3 alpha already present in H441 cells. We have thus identified a gene regulatory element through which two members of the HNF-3 transcription factor family, HNF-3 alpha and HNF-3 beta, exert opposite effects.
Sawaya
P L
PL
Department of Molecular Genetics, Biochemistry and Microbiology, University of Cincinnati College of Medicine, Ohio 45267-0524.
Luse
D S
DS
D001483:Base Sequence; D001665:Binding Sites; D002460:Cell Line; D004247:DNA; D004268:DNA-Binding Proteins / Q000378:metabolism*; D006367:HeLa Cells; D051541:Hepatocyte Nuclear Factor 3-alpha; D051542:Hepatocyte Nuclear Factor 3-beta; D006801:Humans; D008168:Lung / Q000378:metabolism*; D008969:Molecular Sequence Data; D009687:Nuclear Proteins / Q000378:metabolism*; D011401:Promoter Regions, Genetic; D011506:Proteins / Q000235:genetics*; D014157:Transcription Factors; D014158:Transcription, Genetic; D014598:Uteroglobin
D004268:DNA-Binding Proteins; C496499:FOXA1 protein, human; C496502:FOXA2 protein, human; D051541:Hepatocyte Nuclear Factor 3-alpha; D009687:Nuclear Proteins; D011506:Proteins; C556389:SCGB1A1 protein, human; C556391:Scgb1a1 protein, rat; D014157:Transcription Factors; D051542:Hepatocyte Nuclear Factor 3-beta; D004247:DNA; D014598:Uteroglobin