Molecular biology of vasoactive substances

在体外培养的新生大鼠心肌细胞肥大模型中，脑利钠肽(BNP)mRNA表达增加，并在1h内达到最高水平，该作用可被转录抑制剂完全抑制。当富含CT的序列(-1288~-1095)被删除时，克隆的人BNP基因5‘侧翼区的启动子活性降低到30%。RT-PCR检测到两个新的人内皮素-A受体(ET-AR)基因转录本，分别含有199和327个碱基的缺失，缺失的序列分别对应于外显子4和外显子3和4，表明这两个ET-AR转录本是由RNA选择性剪接产生的。该负调控区位于小鼠血管紧张素Ⅱ2型受体基因-453~-225之间，其中含有干扰素调节因子(IRF)结合基序。IRF-2抑制生长和融合细胞中AT2受体的表达，而IRF-1仅增强融合细胞中AT2受体的表达。人前列环素受体基因全长约7.0kb，由3个外显子组成，定位于19号染色体，转录起始点位于ATG起始密码子上游870~872bp。1.2kb的5‘侧翼区缺少传统的TATA和CCAAT盒，但它含有几个顺式作用调控元件，包括一个倒置的CCAAT盒和两个SP-1结合位点的拷贝。

Brain natriuretic peptide (BNP) mRNA increased and reached a maximal level within 1 h in a model of cardiac hypertrophy using cultured neonatal ratventricular cardiocytes, which was completely diminished by a transcriptional inhibitor. The promotor activity of the cloned 5'-flanking region of human BNP gene was reduced to 30% when the CT-rich sequences (-1288 to -1095) were deleted. The BNP gene was assigned to human chromosome 1. Two novel transcripts of the human endothelin-A receptor (ET-AR) gene contained deletions of 199 bp and 327 bp were demonstrated using RT-PCR.The deleted sequences corresponded to exon 4 and exons 3 and 4, respectively, indicating these ET-AR transcripts result from alternative RNA splicing. The putative negative regulatory region was located between -453 and -225 of mouse angiotensin II type 2 (AT_2) receptor gene, in which the interferon regulatory factor (IRF) binding motif was identified. IRF-2 attenuated the AT2 receptor expression in both growing and confluent R3T3 cells, whereas IRF-1 enhanced AT2 receptor expression in the confluent cells only. The human prostacyclin receptor gene spanned approximately 7.0 kb and was composed of three exons, which was assigned to chromosome 19. The transcription initiation sites were mapped 870-872 bp upstream to the ATG start codon. The 1.2-kb 5'-flanking region lacked conventional TATA and CCAAT boxes, but it contained several cis-acting regulatory elements including an inverted CCAAT box and two copies of SP-1 binding sites.