Transcriptional regulation of the AP-2alpha promoter by BTEB-1 and AP-2rep, a novel wt-1/egr-related zinc finger repressor.
AP-2 transcription factors have been suggested to exert key regulatory functions in vertebrate embryonic development, in tumorigenicity of various cancer cell types, and in controlling cell cycle and apoptotic effector genes. In this study, we investigated transcriptional regulation of the AP-2alpha gene promoter mediated by an autoregulatory element (referred to as A32) with a core consensus AP-2 binding site at position -336 relative to the mRNA initiation site. AP-2 and multiple different nuclear proteins in HeLa and Neuro2A cell extracts form specific bandshifts with the A32 element. By screening a mouse brain cDNA expression library, we isolated two different cDNAs encoding the transcription factor BTEB-1 and a novel zinc finger protein, AP-2rep. AP-2rep reveals a modular structure with homology to transcription factors of the wt-1/egr-1-family. AP-2rep, BTEB-1, and AP-2 interact in a mutually exclusive manner with overlapping binding sites in the A32 element. Transfection studies revealed that BTEB-1 is a strong activator of AP-2alpha promoter activity, whereas cotransfected AP-2alpha resulted in moderate autoactivation of promoter activity. In contrast, AP-2rep confers strong transcriptional repression to the AP-2alpha gene, and we observed an excellent correlation between induction of AP-2rep mRNA expression and downregulation of AP-2alpha mRNA during development of the kidney. In summary, we have identified multiple transcription factors and cloned from an expression library a novel zinc finger silencing factor, AP-2rep, mediating positive and negative regulation of AP-2alpha expression through a set of overlapping cis-regulatory promoter elements.
Imhof
A
A
Institute for Pathology, University of Regensburg Medical School, D-93042 Regensburg, Germany.
Schuierer
M
M
Werner
O
O
Moser
M
M
Roth
C
C
Bauer
R
R
Buettner
R
R
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D001665:Binding Sites; D003001:Cloning, Molecular; D018076:DNA, Complementary; D004268:DNA-Binding Proteins / Q000235:genetics* / Q000378:metabolism*; D051766:Early Growth Response Protein 1; D051767:Early Growth Response Protein 2; D005786:Gene Expression Regulation; D006367:HeLa Cells; D006801:Humans; D017874:Immediate-Early Proteins; D051741:Kruppel-Like Transcription Factors; D051379:Mice; D008969:Molecular Sequence Data; D011401:Promoter Regions, Genetic; D051381:Rats; D011993:Recombinant Fusion Proteins / Q000235:genetics; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism*; D017386:Sequence Homology, Amino Acid; D050656:Transcription Factor AP-2; D014157:Transcription Factors / Q000235:genetics* / Q000378:metabolism*; D014158:Transcription, Genetic; D025721:WT1 Proteins; D016335:Zinc Fingers
D018076:DNA, Complementary; D004268:DNA-Binding Proteins; C497325:EGR1 protein, human; C497326:EGR2 protein, human; D051766:Early Growth Response Protein 1; D051767:Early Growth Response Protein 2; C486109:Egr1 protein, mouse; C486110:Egr1 protein, rat; C497327:Egr2 protein, mouse; C497328:Egr2 protein, rat; D017874:Immediate-Early Proteins; C436492:KLF12 protein, human; C489676:KLF9 protein, human; C489675:Klf9 protein, mouse; D051741:Kruppel-Like Transcription Factors; D011993:Recombinant Fusion Proteins; D012097:Repressor Proteins; C493673:TFAP2A protein, human; C493668:Tfap2a protein, mouse; D050656:Transcription Factor AP-2; D014157:Transcription Factors; D025721:WT1 Proteins; C077017:Klf9 protein, rat