Bauer R, Imhof A, Pscherer A, Kopp H, Moser M, Seegers S, Kerscher M, Tainsky M A, Hofstaedter F, Buettner R
Department of Pathology, University of Regensburg Medical School, Germany.
Nucleic Acids Res. 1994 Apr 25;22(8):1413-20. doi: 10.1093/nar/22.8.1413.
The transcription factor AP-2 is encoded by a gene located on chromosome 6 near the HLA locus. Here we describe the genomic organization of the AP-2 gene including an initial characterization of the promoter. We have mapped two mRNA initiation sites, the entire exon-intron structure and located two polyadenylation sites. The mature AP-2 mRNA is spliced from 7 exons distributed over a region of 18 kb genomic DNA. A recently cloned inhibitory AP-2 protein is generated by alternative usage of a C-terminal exon. The proline-rich transactivation motif is encoded by a single exon within the N-terminal region in contrast to the complex DNA binding and dimerization motif which involves amino acid residues located on four different exons. The sites of mRNA initiation are located 220 and 271 bases upstream from the ATG translation start site. Although the promoter contains no canonical sequence motifs for basal transcription factors, such as TATA-, CCAAT- or SP-1 boxes, it mediates cell-type-specific expression of a CAT reporter gene in PA-1 human teratocarcinoma cells and is inactive in murine F9 teratocarcinoma cells. We demonstrate that the promoter of the AP-2 gene is subject to positive autoregulation by its own gene product. A consensus AP-2 binding site is located at position -622 with respect to the ATG. This site binds specifically to bacterially expressed AP-2 as well as to multiple proteins, including AP-2, present in PA-1 and HeLa cell nuclear extracts. A partial AP-2 promoter fragment including the AP-2 consensus binding site is approximately 5-fold transactivated by cotransfection of an AP-2 expression plasmid.
转录因子AP-2由位于6号染色体上靠近HLA基因座的一个基因编码。在此，我们描述了AP-2基因的基因组结构，包括对其启动子的初步特征分析。我们已确定了两个mRNA起始位点、整个外显子-内含子结构，并定位了两个聚腺苷酸化位点。成熟的AP-2 mRNA由分布在18 kb基因组DNA区域内的7个外显子剪接而成。最近克隆的抑制性AP-2蛋白是通过C末端外显子的选择性使用产生的。富含脯氨酸的反式激活基序由N末端区域内的单个外显子编码，这与涉及位于四个不同外显子上的氨基酸残基的复杂DNA结合和二聚化基序形成对比。mRNA起始位点位于ATG翻译起始位点上游220和271个碱基处。尽管该启动子不包含基础转录因子的典型序列基序，如TATA盒、CCAAT盒或SP-1盒，但它在PA-1人畸胎瘤细胞中介导CAT报告基因的细胞类型特异性表达，而在鼠F9畸胎瘤细胞中无活性。我们证明AP-2基因的启动子受到其自身基因产物的正向自我调节。一个共有AP-2结合位点相对于ATG位于-622位置。该位点特异性结合细菌表达的AP-2以及PA-1和HeLa细胞核提取物中存在的多种蛋白质，包括AP-2。包含AP-2共有结合位点的部分AP-2启动子片段通过共转染AP-2表达质粒可被激活约5倍。
