Inhibition of Human T Cell Leukaemia Virus Type I Long Terminal Repeat Expression by DNA Methylation: Implications for Latency

• Published in: Journal of general virology 1994-11, Vol.75 (11), p.3255-3259
• Main Authors: Cassens, Sven, Ulrich, Uwe, Beimling, Peter, Simon, Dietrich
• Format: Article
• Language: English
• Subjects: Adult; Base Sequence; Chloramphenicol O-Acetyltransferase - biosynthesis; DNA, Viral - chemistry; DNA, Viral - metabolism; DNA-Cytosine Methylases - metabolism; Gene Products, tax - metabolism; Human T-lymphotropic virus 1 - genetics; Human T-lymphotropic virus 1 - isolation & purification; Human T-lymphotropic virus 1 - physiology; Humans; Leukemia, T-Cell - virology; Luciferases - biosynthesis; Methylation; Repetitive Sequences, Nucleic Acid; Restriction Mapping; Tetradecanoylphorbol Acetate - pharmacology; Transcription, Genetic
• ISSN: 0022-1317; 1465-2099
• DOI: 10.1099/0022-1317-75-11-3255

1 Abteilung Virologie, Robert Koch-Institut, Nordufer 20, 13353 Berlin and 2 Abteilung Schuster, Max-Planck-Institut für Molekulare Genetik, Ihnesstrasse 73, 14195 Berlin, Germany Human T cell leukaemia virus type I (HTLV-I) provirus DNA was found to be methylated in patients with adult T cell leukaemia. We have therefore examined the possibility that DNA methylation might contribute to HTLV-I latency. In vitro methylation of HTLV-I long terminal repeat (LTR)-chloramphenicol acetyltransferase or LTR-Luciferase constructs at eight Hpa II sites, a subset of the eukaryotic methylation site CpG, resulted in a three- to fourfold inhibition of transcription in transfected cells. Inhibition of transcription by methylation of all CpG methylation sites using Sss I methylase was much more pronounced (50- to 80-fold). As partial methylation of the LTR showed, methylation of the promoter region was responsible for most of the effect. Whereas cellular stimulation by a combination of phorbol 12-myristate 13-acetate and Tax was able to reverse the Hpa II methylation effect, the inhibition by Sss I methylation was not suppressible under these conditions. The results are in line with a possible function of DNA methylation in HTLV-I latency. Received 28 March 1994; accepted 14 June 1994.