c-fos protooncogene transcription can be modulated by oligonucleotide-mediated formation of triplex structures in vitro.
A homopurine.homopyrimidine sequence of the c-fos promoter was chosen as a target for a triple helix oligonucleotide. Eight DNA oligonucleotides that ranged from 14 to 31 bp were shown to form a triple helix with three sequences within the c-fos promoter region. Reactive derivatives of homopyrimidine oligonucleotides bearing the 5'- or 3'-terminal DNA alkylation aromatic 2-chloroethylamino group were also synthesized. It was concluded, based on the physical properties of the DNA oligonucleotide complex, that the oligonucleotide forms a colinear triplex with the duplex binding sites. We investigated in detail, using electrophoretic mobility and footprinting protection, whether such oligonucleotide.DNA complexes are of benefit in designing high-affinity probes for a natural DNA sequence in the mouse c-fos gene. Our results demonstrate that four different DNA targets within the c-fos promoter region can form triplex structures with synthetic oligonucleotides in a sequence-specific manner. Moreover, in vitro modifications of the retinoblastoma-gene-product-binding site of the c-fos promoter at position -83 in front of the cAMP/cAMP-responsive element binding site and fos-binding site 3/activator-protein-2-like (FBS3/AP-2-like) site at position -431 by triple helix forming oligonucleotides cause dramatic suppression of fos-chloramphenicol acetyltransferase activity in endothelial cells. These results provide a basis for the development of a specific oligonucleotide target forming triplex-DNA complex, and emphasize the importance of a target forming triplex as a basis for control of gene expression and cell proliferation.
Lavrovsky
Y
Y
Rockefeller University, New York 10021, USA.
Stoltz
R A
RA
Vlassov
V V
VV
Abraham
N G
NG
D001483:Base Sequence; D015500:Chloramphenicol O-Acetyltransferase / Q000235:genetics; D004247:DNA / Q000737:chemistry / Q000378:metabolism*; D004591:Electrophoresis, Polyacrylamide Gel; D017930:Genes, Reporter; D016762:Genes, fos / Q000235:genetics*; D008745:Methylation; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D009838:Oligodeoxyribonucleotides / Q000737:chemistry / Q000378:metabolism*; D011401:Promoter Regions, Genetic; D013463:Sulfuric Acid Esters / Q000378:metabolism / Q000494:pharmacology; D014158:Transcription, Genetic
D009838:Oligodeoxyribonucleotides; D013463:Sulfuric Acid Esters; C051802:triplex DNA; D004247:DNA; D015500:Chloramphenicol O-Acetyltransferase; C007482:dimethyl sulfate