Redmann A, Rasch A, Tourné H, Mann K, Petersenn S
Division of Endocrinology, Medical Center, University of Essen, Essen, Germany.
Horm Metab Res. 2007 May;39(5):359-65. doi: 10.1055/s-2007-976540.
Somatostatin (SRIF) exerts inhibitory effects on virtually all endocrine and exocrine secretions. At least five distinct human SRIF receptors have been identified ( SST1-SST5). Analysis of the promoter region may provide tools to understand transcriptional regulation of SSTS in various tissues, indicating specific functions. Transcriptional regulation of the human SST1 was analyzed in the present study. Total RNA from a human somatotropic pituitary tumor was reverse transcribed. 5'cDNA regions of the human SST1 were cloned using an adapted inverse PCR method. Among the 15 PCR clones analyzed, 9 demonstrated an extended 5'-utr of 266 nucleotides, determining a thymidine residue as a major transcription start site. No introns were evident in the 5'-utr region. The promoter region lacked consensus sites for TATA or CAAT boxes, YY1, or an initiator sequence, but contained two CpG islands. Different lengths of 5'-flanking regions cloned by PCR were placed upstream of the luciferase reporter gene and transiently transfected into various cell lines. The 2834 nt of the promoter region directed significant transcriptional activity in a somatotropic pituitary cell line, but neither in COS-7 monkey kidney cells nor in AtT-20 murine corticotrope cells. Transcriptional activity was not affected by incubation with various hormones. Several putative transcription factor binding sites inducing the cell-type specific activity were identified.
生长抑素（SRIF）对几乎所有内分泌和外分泌都有抑制作用。已鉴定出至少五种不同的人类SRIF受体（SST1 - SST5）。对启动子区域的分析可能提供工具来了解SSTS在各种组织中的转录调控，从而表明其特定功能。本研究分析了人类SST1的转录调控。从人类生长激素垂体瘤中提取的总RNA进行逆转录。使用改进的反向PCR方法克隆人类SST1的5' cDNA区域。在分析的15个PCR克隆中，9个显示出266个核苷酸的延长5'-非翻译区，确定胸苷残基为主要转录起始位点。在5'-非翻译区没有明显的内含子。启动子区域缺乏TATA或CAAT框、YY1或起始序列的共有位点，但包含两个CpG岛。通过PCR克隆的不同长度的5'-侧翼区域被置于荧光素酶报告基因的上游，并瞬时转染到各种细胞系中。启动子区域的2834 nt在生长激素垂体细胞系中具有显著的转录活性，但在COS - 7猴肾细胞和AtT - 20鼠促肾上腺皮质激素细胞中均无活性。转录活性不受与各种激素孵育的影响。鉴定出了几个诱导细胞类型特异性活性的推定转录因子结合位点。
