HERV-K-T47D-Related Long Terminal Repeats Mediate Polyadenylation of Cellular Transcripts

Baust, Corinna; Seifarth, Wolfgang; Germaier, Herbert; Hehlmann, Rüdiger; Leib-Mösch, Christine

doi:10.1006/geno.2000.6175

Cited by 39 publications

(26 citation statements)

References 22 publications

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“…Additionally, all the retrotransposon inserts were found in the same strand as the ORFs of the target genes. Taken together, the above data may indicate that either the LTR region or the polyadenylation site of the retrotransposons may actually be used as an alternative promoter or alternative polyadenylation site for the target genes, as described for other organisms (4,38,43).…”

Section: Vol 78 2004 Schistosoma Mansoni Ltr and Non-ltr Transposonmentioning

confidence: 67%

Saci-1, -2, and -3 and Perere, Four Novel Retrotransposons with High Transcriptional Activities from the Human Parasite Schistosoma mansoni

DeMarco¹,

Kowaltowski²,

Machado

et al. 2004

J Virol

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Using the data set of 180,000 expressed sequence tags (ESTs) of the blood fluke Schistosoma mansoni generated recently by our group, we identified three novel long-terminal-repeat (LTR)-and one novel non-LTR-expressed retrotransposon, named Saci-1, -2, and -3 and Perere, respectively. Full-length sequences were reconstructed from ESTs and have deduced open reading frames (ORFs) with several uncorrupted features, characterizing them as possible active retrotransposons of different known transposon families. Alignment of reconstructed sequences to available preliminary genome sequence data confirmed the overall structure of the transposons. The frequency of sequenced transposon transcripts in cercariae was 14% of all transcripts from that stage, twofold higher than that in schistosomula and three-to fourfold higher than that in adults, eggs, miracidia, and germ balls. We show by Southern blot analysis, by EST annotation and tallying, and by counting transposon tags from a Social Analysis of Gene Expression library, that the four novel retrotransposons exhibit a 10-to 30-fold lower copy number in the genome and a 4-to 200-fold-higher transcriptional rate per copy than the four previously described S. mansoni retrotransposons. Such differences lead us to hypothesize that there are two different populations of retrotransposons in S. mansoni genome, occupying different niches in its ecology. Examples of retrotransposon fragment inserts were found into the 5 and 3 untranslated regions of four different S. mansoni target gene transcripts. The data presented here suggest a role for these elements in the dynamics of this complex human parasite genome.

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Section: Vol 78 2004 Schistosoma Mansoni Ltr and Non-ltr Transposonmentioning

confidence: 67%

Saci-1, -2, and -3 and Perere, Four Novel Retrotransposons with High Transcriptional Activities from the Human Parasite Schistosoma mansoni

DeMarco¹,

Kowaltowski²,

Machado

et al. 2004

J Virol

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“…In particular, the provision of a premature polyadenylation site can result in truncated transcripts and eventually in genetic disorders. However, examples of adopted beneficial retroelement-derived polyadenylation sites have also been reported (74). One such example of an ''exaptation,'' a process in which a retroelement has taken on new functions for a genome, is the generation of the secreted form of the human transmembrane protein attractin.…”

Section: Biological Implications Of Retroelement Inheritancementioning

confidence: 99%

Retroelements and the human genome: New perspectives on an old relation

Bannert

Kurth

2004

Proc. Natl. Acad. Sci. U.S.A.

466

423

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Retroelements constitute a large portion of our genomes. One class of these elements, the human endogenous retroviruses (HERVs), is comprised of remnants of ancient exogenous retroviruses that have gained access to the germ line. After integration, most proviruses have been the subject of numerous amplifications and have suffered extensive deletions and mutations. Nevertheless, HERV-derived transcripts and proteins have been detected in healthy and diseased human tissues, and HERV-K, the youngest, most conserved family, is able to form virus-like particles. Although it is generally accepted that the integration of retroelements can cause significant harm by disrupting or disregulating essential genes, the role of HERV expression in the etiology of malignancies and autoimmune and neurologic diseases remains controversial. In recent years, striking evidence has accumulated indicating that some proviral sequences and HERV proteins might even serve the needs of the host and are therefore under positive selection. The remarkable progress in the analysis of host genomes has brought to light the significant impact of HERVs and other retroelements on genetic variation, genome evolution, and gene regulation.A lmost half of the mammalian genome is derived from ancient transposable elements. The two general types, (DNA)-transposons and retroelements, often regarded as ''selfish DNA parasites or junk DNA,'' encompass Ϸ2.8% and 42.2% of the human genome, respectively (1, 2). This striking finding is one of the many insights from recent large-scale sequencing projects that have provided the most valuable information in this field since the initial discovery of mobile elements in 1956 by Barbara McClintock (3, 4). Whereas DNA-transposons amplify without an RNA intermediate, retroelements rely on an RNA transcript that is retrotranscribed by a reverse transcriptase before integration in the genome. Here, we briefly review the characteristics of retroelements, their present classification, and the available evidence for their biological significance and function in normal and pathological processes. The focus is on human endogenous retroviruses (HERVs), the remnants of ancient germ-cell infections. Although most of the HERV proviruses have undergone extensive deletions and mutations, some have retained ORFs coding for functional proteins. A few families, including the HERV-K (HML-2) group, have been shown to form viral particles (5, 6), and an apparently intact provirus has recently been discovered in a small fraction of the human population, indicating a very recent acquisition (5-7). Classification of RetroelementsRetroelements constitute 90% of the Ϸ3 million transposable elements present in the human genome (1). They are split into two large groups, the non-LTR and LTR elements (Fig. 1). Two of the non-LTR members are present in extremely high copy numbers in the mammalian germ line: the short interspersed elements (SINE) with the prominent Alu and MIR repeats and the long-terminal interspersed elements (LINE) containing the...

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“…Akopov et al (1998) have noted that such sequences have the capacity to modify the expression of neighboring genes, and suggested that such modifications may have been acquired in the course of human evolution. The HERV-K-T47D-related LTR element has mediated pofyadenyktion of cellular transcripts (Baust et al, 2000). In the case of another retroelement (the HERV-F LTR element), a similar phenomenon was observed in relation to the Kriippel-related zinc finger gene ZNF195 (Kjellman et al, 1999).…”

Section: Resultsmentioning

confidence: 89%

Identification and phylogenetic analysis of long terminal repeat elements of the human ehdogenous retrovims K family (HEW‐K) from a human brain cDNA library

Kim¹,

Lee

2001

Korean Journal of Biological Sciences

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HERV-K-T47D-Related Long Terminal Repeats Mediate Polyadenylation of Cellular Transcripts

Cited by 39 publications

References 22 publications

Saci-1, -2, and -3 and Perere, Four Novel Retrotransposons with High Transcriptional Activities from the Human Parasite Schistosoma mansoni

Saci-1, -2, and -3 and Perere, Four Novel Retrotransposons with High Transcriptional Activities from the Human Parasite Schistosoma mansoni

Retroelements and the human genome: New perspectives on an old relation

Identification and phylogenetic analysis of long terminal repeat elements of the human ehdogenous retrovims K family (HEW‐K) from a human brain cDNA library

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