Ishizuka T, Ino H, Sawa K, Suzuki N, Tatibana M
Department of Biochemistry, Chiba University, School of Medicine, Japan.
Gene. 1995 Dec 12;166(2):267-71. doi: 10.1016/0378-1119(95)00650-8.
While cyclin-dependent kinases, such as CDC2 and CDK2, are key regulators of cell-cycle progression, cyclin-dependent kinase 5 (CDK5) is highly expressed in mature neurons with no evident cell-cycle regulation. The 5'-region of the mouse CDK5 gene was isolated and sequenced. The isolated clone included exons 1 through 7. The 5'-flanking region has a high G+C content. There is no TATA box around the transcriptional start points (tsp), as determined by primer extension analysis. One CCAAT box, one AP-1-binding site, two AP-2-binding sites, and one cAMP-responsive element are located upstream from the tsp. Promoter/cat fusion assays showed that the 5.8-kb fragment of this 5'-flanking sequence possessed the promoter activities expressing cat in rat PC12 pheochromocytoma cells. The effect of deletions of the promoter suggested the presence of two negative control elements located from -2.9 kb to -546 bp, and from -212 to -155 upstream from the 5' end of the tsp. Two positive elements from bp -300 to -212 and from -155 to -41 were also detected. In the element from bp -300 to -212, there was a putative NF-IL6-binding sequence. Thus, the CDK5 promoter region contains multiple positive and negative cis-acting regulatory elements, an arrangement which suggests that the regulation of transcription of CDK5 is under complex control.
细胞周期蛋白依赖性激酶，如CDC2和CDK2，是细胞周期进程的关键调节因子，而细胞周期蛋白依赖性激酶5（CDK5）在成熟神经元中高表达，且无明显的细胞周期调控。分离并测序了小鼠CDK5基因的5'区域。分离得到的克隆包含外显子1至7。5'侧翼区域的G+C含量很高。通过引物延伸分析确定，转录起始点（tsp）周围没有TATA盒。一个CCAAT盒、一个AP-1结合位点、两个AP-2结合位点和一个cAMP反应元件位于tsp上游。启动子/氯霉素乙酰转移酶（CAT）融合分析表明，该5'侧翼序列的5.8 kb片段在大鼠嗜铬细胞瘤PC12细胞中具有表达CAT的启动子活性。启动子缺失的影响表明，在tsp的5'端上游-2.9 kb至-546 bp以及-212至-155处存在两个负调控元件。还检测到从-300 bp至-212以及从-155至-41的两个正调控元件。在-300 bp至-212的元件中，有一个假定的NF-IL6结合序列。因此，CDK5启动子区域包含多个正负顺式作用调控元件，这种排列表明CDK5的转录调控受到复杂的控制。
