scholarly journals Functional Activity of HERV-K-T47D-Related Long Terminal Repeats

Virology ◽  
2001 ◽  
Vol 283 (2) ◽  
pp. 262-272 ◽  
Author(s):  
Corinna Baust ◽  
Wolfgang Seifarth ◽  
Ulrike Schön ◽  
Rüdiger Hehlmann ◽  
Christine Leib-Mösch
Keyword(s):  
Functional Activity ◽  
Long Terminal Repeats ◽  
Terminal Repeats

scholarly journals Transactivation of Naturally Occurring HIV-1 Long Terminal Repeats by the JNK Signaling Pathway

2000 ◽  
Vol 275 (27) ◽  
pp. 20382-20390 ◽  
Author(s):  
Peifeng Chen ◽  
Egbert Flory ◽  
Andris Avots ◽  
Bruce W. M. Jordan ◽  
Frank Kirchhoff ◽  
...  
Keyword(s):  
Signaling Pathway ◽  
Long Terminal Repeats ◽  
Jnk Signaling ◽  
Naturally Occurring ◽  
Jnk Signaling Pathway ◽  
Terminal Repeats ◽  
Hiv 1

scholarly journals Spontaneous HTLV-1 transcription is accompanied by distinct epigenetic changes in the 5′ and 3′ long terminal repeats

2018 ◽  
Vol 3 ◽  
pp. 105 ◽  
Author(s):  
Michi Miura ◽  
Paola Miyazato ◽  
Yorifumi Satou ◽  
Yuetsu Tanaka ◽  
Charles R.M. Bangham
Keyword(s):  
Histone Modifications ◽  
Insertion Site ◽  
Rapid Change ◽  
Epigenetic Modifications ◽  
The Body ◽  
Ctcf Binding ◽  
Ctcf Binding Site ◽  
Long Terminal Repeats ◽  
Terminal Repeats ◽  
The Impact

Background:The human retrovirus HTLV-1 inserts the viral complementary DNA of 9 kb into the host genome. Both plus- and minus-strands of the provirus are transcribed, respectively from the 5′ and 3′ long terminal repeats (LTR). Plus-strand expression is rapid and intense once activated, whereas the minus-strand is transcribed at a lower, more constant level. To identify how HTLV-1 transcription is regulated, we investigated the epigenetic modifications associated with the onset of spontaneous plus-strand expression and the potential impact of the host factor CTCF.Methods:Patient-derived peripheral blood mononuclear cells (PBMCs) and in vitro HTLV-1-infected T cell clones were examined. Cells were stained for the plus-strand-encoded viral protein Tax, and sorted into Tax+and Tax–populations. Chromatin immunoprecipitation and methylated DNA immunoprecipitation were performed to identify epigenetic modifications in the provirus. Bisulfite-treated DNA fragments from the HTLV-1 LTRs were sequenced. Single-molecule RNA-FISH was performed, targeting HTLV-1 transcripts, for the estimation of transcription kinetics. The CRISPR/Cas9 technique was applied to alter the CTCF-binding site in the provirus, to test the impact of CTCF on the epigenetic modifications.Results:Changes in the histone modifications H3K4me3, H3K9Ac and H3K27Ac were strongly correlated with plus-strand expression. DNA in the body of the provirus was largely methylated except for the pX and 3′ LTR regions, regardless of Tax expression. The plus-strand promoter was hypomethylated when Tax was expressed. Removal of CTCF had no discernible impact on the viral transcription or epigenetic modifications.Conclusions:The histone modifications H3K4me3, H3K9Ac and H3K27Ac are highly dynamic in the HTLV-1 provirus: they show rapid change with the onset of Tax expression, and are reversible. The HTLV-1 provirus has an intrinsic pattern of epigenetic modifications that is independent of both the provirus insertion site and the chromatin architectural protein CTCF which binds to the HTLV-1 provirus.

Functional analysis of the long terminal repeats of intracisternal A-particle genes: sequences within the U3 region determine both the efficiency and direction of promoter activity

1988 ◽  
Vol 8 (3) ◽  
pp. 1093-1102
Author(s):  
R J Christy ◽  
R C Huang
Keyword(s):  
Reporter Gene ◽  
Promoter Activity ◽  
Transcriptional Activity ◽  
Antisense Transcription ◽  
Regulatory Elements ◽  
Deletion Mapping ◽  
Long Terminal Repeats ◽  
Terminal Repeats ◽  
Nuclease Mapping ◽  
Intracisternal A Particle

The transcriptional activity of five intracisternal A-particle (IAP) long terminal repeats (LTRs) in mouse embryonal carcinoma PCC3-A/1 cells and in Ltk- cells was determined. We tested the promoter activity of the LTRs by coupling them to the reporter gene chloramphenicol acetyltransferase (CAT) or guanosine-xanthine phosphoribosyltransferase (gpt). Each LTR was tested for promoter function in both the sense (5' to 3') and antisense (3' to 5') orientation preceding the reporter gene. The transcriptional activity of individual IAP gene LTRs varied considerably, and the LTR from IAP81 possessed promoter activity in both directions. The bidirectional activity of the IAP81 LTR confirmed by monitoring Ecogpt expression in stably transfected Ltk- cells, with the initiation sites for sense and antisense transcription being localized to within the IAP81 LTR by S1 nuclease mapping. Deletions of LTR81 show that for normal 5'-to-3' gene transcription (sense direction), the 3'U3/R region determines the basal level of transcription, whereas sequences within the 5'U3 region enhance transcription four- to fivefold. Deletion mapping for antisense transcription indicates that a 64-base-pair region (nucleotides 47 to 110) within the U3 region is essential for activity. These data indicate that the U3 region contains all the regulatory elements for bidirectional transcription in IAP LTRs.

Four Classes of HERV-K Long Terminal Repeats and Their Relative Promoter Strengths for Transcription

1997 ◽  
Vol 4 (2-3) ◽  
pp. 78-82
Author(s):  
David E. Mold ◽  
Tzyy-Choou Wu ◽  
Frederic Askin ◽  
Ru Chih C. Huang
Keyword(s):  
Long Terminal Repeats ◽  
Terminal Repeats
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