Induction of Tax i expression in MT-4 cells by 5-azacytidine leads to protein binding in the HTLV-1 LTR in vivo.
The Tax I trans-activator protein of the human T-cell leukemia virus I (HTLV-I) enhances viral gene expression through enhancer sequences in the viral LTR. These sequences consist of three imperfect 21-bp repeats (TRE-1) and a region between the promoter central and promoter proximal TRE-1 (known as TRE-2). We have previously described the in vivo footprint of the HTLV-I TRE-1s and TRE-2 in two HTLV-I-infected cell lines, MT-2 and MT-4. MT-2 is a high-level producer of virus and shows significant DNA-protein interactions within the TRE-1s and TRE-2. In contrast, the proviral DNA in MT-4 cells is heavily methylated and produces no detectable virus. In this report, we describe the footprints of the TRE-1s and TRE-2 in MT-4 cells that were induced to express high levels of viral proteins by treatment with 5-azacytidine, a potent inhibitor of methylation. The footprints of the TRE-1s in 5-azacytidine-treated MT-4 cells were virtually identical to those observed in MT-2 cells. In contrast, the footprints within the TRE-2 region of 5-azacytidine-treated MT-4 cells did not resemble those in either MT-2 or MT-4 cells.
Datta
S
S
Cancer Research Institute, University of California, Irvine, California 92697, USA.
Kothari
N H
NH
Fan
H
H
D001374:Azacitidine / Q000494:pharmacology*; D001483:Base Sequence; D002460:Cell Line; D018983:DNA Footprinting / Q000379:methods*; D015967:Gene Expression Regulation, Viral; D016356:Gene Products, tax / Q000235:genetics / Q000378:metabolism*; D015368:Human T-lymphotropic virus 1 / Q000235:genetics* / Q000378:metabolism; D006801:Humans; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction; D013601:T-Lymphocytes / Q000378:metabolism; D020079:Terminal Repeat Sequences / Q000235:genetics / Q000502:physiology*; D014162:Transfection
D016356:Gene Products, tax; D001374:Azacitidine