Zhou Q Y, Li C, Civelli O
Vollum Institute for Advanced Biomedical Research, Oregon Health Sciences University, Portland 97201.
J Neurochem. 1992 Nov;59(5):1875-83. doi: 10.1111/j.1471-4159.1992.tb11023.x.
Genomic and cDNA clones encoding the rat D1 receptor were isolated and sequenced. Comparison of the D1 receptor cDNA and genomic sequences revealed that the rat D1 receptor gene is organized into two exons separated by a small intron in the 5' untranslated region of its mRNA. The transcription start site is located 864 bp upstream from the translational initiation site. The 5'-flanking sequences of the D1 receptor gene do not contain TATA and CAAT canonical sequences, but have a high G+C content, potential cyclic AMP and glucocorticoid response element sequences, and binding sites for transcription factors such as Sp1, Ap1, and Ap2. Transfection studies using the D1 5'-flanking sequence and CAT gene fusion constructs have demonstrated that (1) the D1 promoter is active in D1-expressing neuroblastoma NS20Y cells, but inactive in D1-deficient glioma C6 and kidney 293 cells, (2) the information contained within 735 bp of 5'-flanking sequence of the D1 gene appears to be sufficient to confer its cell-specific expression, and (3) the D1 gene promoter responds to cyclic AMP induction, suggesting the existence of an auto-regulation mechanism by which the stimulation of D1 receptor exerts a positive feedback on its own gene expression.
分离并测序了编码大鼠D1受体的基因组克隆和cDNA克隆。对D1受体cDNA和基因组序列的比较显示，大鼠D1受体基因由两个外显子组成，在其mRNA的5'非翻译区被一个小内含子隔开。转录起始位点位于翻译起始位点上游864 bp处。D1受体基因的5'侧翼序列不包含TATA和CAAT典型序列，但具有高G + C含量、潜在的环磷酸腺苷和糖皮质激素反应元件序列，以及转录因子如Sp1、Ap1和Ap2的结合位点。使用D1 5'侧翼序列和CAT基因融合构建体的转染研究表明：（1）D1启动子在表达D1的神经母细胞瘤NS20Y细胞中具有活性，但在缺乏D1的胶质瘤C6和肾293细胞中无活性；（2）D1基因5'侧翼序列735 bp内包含的信息似乎足以赋予其细胞特异性表达；（3）D1基因启动子对环磷酸腺苷诱导有反应，提示存在一种自调节机制，通过该机制D1受体的刺激对其自身基因表达产生正反馈。
