Triplex formation at the rat neu gene utilizing imidazole and 2'-deoxy-6-thioguanosine base substitutions.
Triplex formation at the rat neu gene utilizing imidazole and 2'-deoxy-6-thioguanosine base substitutions.
复制标题
利用咪唑和 2-脱氧-6-硫鸟苷碱基取代在大鼠 neu 基因上形成三链体。
DOI：
10.1021/bi00006a026
复制
发表时间：
1995
期刊：
影响因子：
2.9
通讯作者：
Hogan,ME
中科院分区：
文献类型：
--
作者：
Gee,JE;Revankar,GR;Rao,TS;Hogan,ME
Revised Manuscript Received November 17, 1994® abstract: Triplex-forming oligodeoxyribonucleotides (TFOs) can be designed so as to form antiparallel triple helices with duplex DNA by means of GGC and TAT or AAT base triplets, and these have been shown to be useful as sequence-specific DNA binding agents. Using TFOs targetedto the promoter region of the rat neu oncogene, it is shown here that substitution of an imidazole-nucleoside chimera at a single site in a neu specific TFO results in an increase in TFO binding affinity and specificity. This effect is discussed in terms of the stabilizing effect of local imidazole-TA triplet formation. It is also found that site-selective substitution of 2'-deoxy-6-thioguanosine for guanosine (S6-dG) in the TFO results in an increase in triplex formation in the presence of physiological levels of potassium ion. The utility and positioning of S6-dG base substitutions is discussed in the context of an intramolecular tetrad model.Homopurine—homopyrimidine-rich tracts of DNA such as the ones found in the rat neu promoter have been shown to be good targets for binding by triplex-forming oligonucle-otides (TFOs) 1 (Cooney et al., 1988; Durland et al., 1990, 1991; Helene, 1991; Maher et al., 1992; Miller et al., 1992; Gee & Miller, 1992). A G-rich tract in the human c-myc promoter was shown to form a triplex readily with G-rich TFOs targeted to it (Cooney et al., 1988; Durland et al., 1991). TFOs have also been shown to bind to sites in the EGFR, mouse insulin receptor (Durland et al., 1991), and HER2 (Milligan et al., 1993) promoters. The GCbox used as a binding site for the Spl transcription factor has also been successfully targeted in an artificial construct (Maher et al., 1992), the humandihydrofolate reductase promoter (Gee et al., 1992), and in the humanimmunodeficiency virus long terminal repeat (McShan et al., 1992). Binding of synthetic oligonucleotides so as to form a triple helix with duplex DNA has beenshown to repress transcription, presumably by preventing the binding of transcription factors to gene promoters (Cooney et al., 1988; Helene, 1991; Maher et al., 1992) or by distorting the DNA duplex to the point that a transcription initiation complex is destabilized (Maher et al., 1992). Transcription from the c-myc promoter has beenshown to be repressed by triplex formation (Cooney et al., 1988). Recent work has also indicated triplex-mediated transcriptional inhibition of the HER2 promoter (Ebbinghaus et al., 1993).
