TY - JOUR
T1 - Transcriptional block of HTLV-I LTR by sequence-specific methylation
AU - Saggioro, Daniela
AU - Forino, Monica
AU - Chieco-Bianchi, Luigi
PY - 1991
Y1 - 1991
N2 - HTLV-1 infection is characterized by low viremia and restricted viral expression. While the mechanisms regulating viral latency are poorly understood, it is believed that interactions between viral and host cellular factor(s) are involved. Several lines of evidence indicate that HTLV-I provinus may be methylated in primary ATL leukemic cells. To determine whether methylation of the viral promoting sequences was sufficient to inhibit gene transcription, we methylated the HTLV-I LTR enzymatically at the Hpall (CCGG) sites. HTLV-I LTR contains several Hpall methylase-sensitive sites, and some involve one of the three 21-bp motifs, responsible for tax induction, as well as sequences that respond to phorbol 12-myristate 13-acetate (PMA)We found that CpG site-specific methylation of HTLV-I LTR sequences inhibits their transcriptional activation mediated by both tax product and PMA. This transcriptional block, however, was overcome when tax product and PMA were added together, thus indicating that tax and PMA act synergistically in bypassing the transcriptional block exerted by methylation.
AB - HTLV-1 infection is characterized by low viremia and restricted viral expression. While the mechanisms regulating viral latency are poorly understood, it is believed that interactions between viral and host cellular factor(s) are involved. Several lines of evidence indicate that HTLV-I provinus may be methylated in primary ATL leukemic cells. To determine whether methylation of the viral promoting sequences was sufficient to inhibit gene transcription, we methylated the HTLV-I LTR enzymatically at the Hpall (CCGG) sites. HTLV-I LTR contains several Hpall methylase-sensitive sites, and some involve one of the three 21-bp motifs, responsible for tax induction, as well as sequences that respond to phorbol 12-myristate 13-acetate (PMA)We found that CpG site-specific methylation of HTLV-I LTR sequences inhibits their transcriptional activation mediated by both tax product and PMA. This transcriptional block, however, was overcome when tax product and PMA were added together, thus indicating that tax and PMA act synergistically in bypassing the transcriptional block exerted by methylation.
UR - http://www.scopus.com/inward/record.url?scp=0025779988&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0025779988&partnerID=8YFLogxK
U2 - 10.1016/0042-6822(91)90649-V
DO - 10.1016/0042-6822(91)90649-V
M3 - Article
C2 - 2024480
AN - SCOPUS:0025779988
VL - 182
SP - 68
EP - 75
JO - Virology
JF - Virology
SN - 0042-6822
IS - 1
ER -