Hélène C, Giovannangeli C, Guieysse-Peugeot A L, Praseuth D
Laboratoire de Biophysique, INSERM U 201, CNRS URA 481, Paris, France.
Ciba Found Symp. 1997;209:94-102; discussion 102-6. doi: 10.1002/9780470515396.ch8.
Control of gene expression at the transcriptional level can be achieved with triplex-forming oligonucleotides provided that the target sequence is accessible within the chromatin structure of cell nuclei. Using oligonucleotide-psoralen conjugates as probes we have shown that the promoter region of the gene encoding the alpha subunit of the interleukin 2 receptor and the polypurine tract of integrated HIV provirus can form sequence-specific, triple-helical complexes in cell cultures. Oligonucleotide-intercalator conjugates can inhibit transcription initiation by competing with transcription factor binding. Oligonucleotide analogues containing N3'-->P5' phosporamidate linkages form stable triple helices that are able to arrest transcription at the elongation step. A triple helix can also be formed on a single-stranded target by clamp oligonucleotides. A clamp targeted to the polypurine tract of HIV RNA is able to block reverse transcription of the viral RNA.
只要靶序列在细胞核的染色质结构中可及，就可以用形成三链体的寡核苷酸在转录水平实现基因表达的调控。使用寡核苷酸 - 补骨脂素缀合物作为探针，我们已经表明，编码白细胞介素2受体α亚基的基因的启动子区域和整合的HIV原病毒的聚嘌呤序列在细胞培养物中可以形成序列特异性的三螺旋复合物。寡核苷酸 - 嵌入剂缀合物可以通过与转录因子结合竞争来抑制转录起始。含有N3'→P5'磷酰胺酸酯键的寡核苷酸类似物形成稳定的三螺旋，能够在延伸步骤阻止转录。钳形寡核苷酸也可以在单链靶标上形成三螺旋。靶向HIV RNA聚嘌呤序列的钳形物能够阻断病毒RNA的逆转录。
