Sp1 and Sp3 Are important regulators of AP-2gamma gene transcription.
AP-2gamma is a member of the AP-2 transcription factor family, is highly enriched in the trophoblast cell lineage, and is essential for placental development. In an effort to identify factors regulating AP-2gamma gene expression, we isolated and characterized the promoter and 5'-flanking region of the mouse and human AP-2gamma genes. The transcription start site of the mouse AP-2gamma gene was mapped by primer extension and 5' rapid amplification of cDNA ends. Deletion analysis of the 5'-flanking region revealed a 704-base pair (bp) sequence located approximately 6 kilobases (kb) upstream of the transcription start site that is required for enhanced expression in trophoblast cells. Additional gene transfer studies showed that basal promoter activity resides within a highly conserved, approximately 200-bp DNA sequence located immediately upstream of the transcription start site. The conserved region is highly GC-rich and lacks typical TATA or CCAAT boxes. Multiple potential Sp- and AP-2-binding sites are clustered within this region. Electrophoretic mobility shift assays demonstrated that Sp1 and Sp3 bind to three sites in the promoter region of the mouse AP-2gamma gene. Combined mutation of the three putative Sp sites reduced promoter activity by 80% in trophoblast and nontrophoblast cells, demonstrating the functional importance of these sites in regulating AP-2gamma gene expression. In summary, we have identified a potential trophoblast cell-specific regulatory element located approximately 6 kb upstream of the murine AP-2gamma gene transcription start site, and we have shown that Sp1 and Sp3 bind to cis-regulatory elements located in the promoter proximal region and contribute to basal promoter activity.
Li
Mei
M
Department of Biochemistry and Molecular Biology, University of Texas Medical School, Houston, Texas 77030, USA.
Kellems
Rodney E
RE
D024506:5' Flanking Region; D000818:Animals; D001483:Base Sequence; D001665:Binding Sites; D002478:Cells, Cultured; D003001:Cloning, Molecular; D004268:DNA-Binding Proteins / Q000235:genetics* / Q000378:metabolism*; D005260:Female; D005786:Gene Expression Regulation; D006801:Humans; D051379:Mice; D008969:Molecular Sequence Data; D011247:Pregnancy; D011401:Promoter Regions, Genetic; D016329:Sp1 Transcription Factor / Q000235:genetics / Q000378:metabolism*; D051705:Sp3 Transcription Factor; D050656:Transcription Factor AP-2; D014157:Transcription Factors / Q000235:genetics* / Q000378:metabolism*; D024363:Transcription Initiation Site; D014158:Transcription, Genetic; D014327:Trophoblasts / Q000166:cytology / Q000502:physiology
D004268:DNA-Binding Proteins; C497121:SP3 protein, human; D016329:Sp1 Transcription Factor; C497122:Sp3 protein, mouse; C493679:TFAP2C protein, human; C583890:Tfap2c protein, mouse; D050656:Transcription Factor AP-2; D014157:Transcription Factors; D051705:Sp3 Transcription Factor