Investigation of the nucleotide sequence of the HIV-1 LTR showed the presence of four novel short DNA regions which are homologous to the recognition site for the cellular transcription factor AP-1. Four short oligonucleotide hybrids containing these potential AP-1 sites were constructed and used in gel retardation assays and in competition experiments in order to determine the role of the AP-L protein in the regulation of HIV-1 expression. The breast MDA MB 468 and cervical HeLa turner cell lines, which are known to overexpress the AP-1 protein were used in a gel retardation assay as a control to study the affinity of the AP-1 to synthesized oligonucleotide sequences. We have observed specific binding of nuclear factor AP-1 to three of these oligonucleotide hybrids. These results demonstrate the presence of three novel AP-1 binding sites on HIV-1 LTR, one of which was found within the TAR element and in the Tat protein binding region. Moreover, they suggest that AP-1 could be contributing to HIV-1 transcriptional regulation through its interaction with the AP-1 binding sites of HIV-1 LTR.

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