scholarly journals The Long Terminal Repeats of ERV6 Are Activated in Pre-Implantation Embryos of Cynomolgus Monkey

Cells ◽  
2021 ◽  
Vol 10 (10) ◽  
pp. 2710
Author(s):  
Kui Duan ◽  
Chen-Yang Si ◽  
Shu-Mei Zhao ◽  
Zong-Yong Ai ◽  
Bao-Hua Niu ◽  
...  
Keyword(s):  
Gene Regulation ◽  
Signaling Pathways ◽  
Endogenous Retroviruses ◽  
Long Terminal Repeats ◽  
Repeat Elements ◽  
Cynomolgus Monkeys ◽  
Trophoblast Stem Cells ◽  
Embryo Cells ◽  
Mammalian Embryos ◽  
Estrogen Related Receptor

Precise gene regulation is critical during embryo development. Long terminal repeat elements (LTRs) of endogenous retroviruses (ERVs) are dynamically expressed in blastocysts of mammalian embryos. However, the expression pattern of LTRs in monkey blastocyst is still unknown. By single-cell RNA-sequencing (seq) data of cynomolgus monkeys, we found that LTRs of several ERV families, including MacERV6, MacERV3, MacERV2, MacERVK1, and MacERVK2, were highly expressed in pre-implantation embryo cells including epiblast (EPI), trophectoderm (TrB), and primitive endoderm (PrE), but were depleted in post-implantation. We knocked down MacERV6-LTR1a in cynomolgus monkeys with a short hairpin RNA (shRNA) strategy to examine the potential function of MacERV6-LTR1a in the early development of monkey embryos. The silence of MacERV6-LTR1a mainly postpones the differentiation of TrB, EPI, and PrE cells in embryos at day 7 compared to control. Moreover, we confirmed MacERV6-LTR1a could recruit Estrogen Related Receptor Beta (ESRRB), which plays an important role in the maintenance of self-renewal and pluripotency of embryonic and trophoblast stem cells through different signaling pathways including FGF and Wnt signaling pathways. In summary, these results suggest that MacERV6-LTR1a is involved in gene regulation of the pre-implantation embryo of the cynomolgus monkeys.

scholarly journals Sequence Analysis of Porcine Endogenous Retrovirus Long Terminal Repeats and Identification of Transcriptional Regulatory Regions

2003 ◽  
Vol 77 (1) ◽  
pp. 142-149 ◽  
Author(s):  
Carolyn A. Wilson ◽  
Sabahat Laeeq ◽  
Armin Ritzhaupt ◽  
Winston Colon-Moran ◽  
Fayth K. Yoshimura
Keyword(s):  
Sequence Analysis ◽  
Animal Species ◽  
Cell Types ◽  
Endogenous Retrovirus ◽  
Endogenous Retroviruses ◽  
Long Terminal Repeats ◽  
Repeat Elements ◽  
Porcine Endogenous Retrovirus ◽  
Transcriptional Regulatory ◽  
Different Cell Types

ABSTRACT Porcine cells express endogenous retroviruses, some of which are infectious for human cells. To better understand the replication of these porcine endogenous retroviruses (PERVs) in cells of different types and animal species, we have performed studies of the long terminal repeat (LTR) region of known gammaretroviral isolates of PERV. Nucleotide sequence determination of the LTRs of PERV-NIH, PERV-C, PERV-A, and PERV-B revealed that the PERV-A and PERV-B LTRs are identical, whereas the PERV-NIH and PERV-C LTRs have significant sequence differences in the U3 region between each other and with the LTRs of PERV-A and PERV-B. Sequence analysis revealed a similar organization of basal promoter elements compared with other gammaretroviruses, including the presence of enhancer-like repeat elements. The sequences of the PERV-NIH and PERV-C repeat element are similar to that of the PERV-A and PERV-B element with some differences in the organization of these repeats. The sequence of the PERV enhancer-like repeat elements differs significantly from those of other known gammaretroviral enhancers. The transcriptional activities of the PERV-A, PERV-B, and PERV-C LTRs relative to each other were similar in different cell types of different animal species as determined by transient expression assays. On the other hand, the PERV-NIH LTR was considerably weaker in these cell types. The transcriptional activity of all PERV LTRs was considerably lower in porcine ST-IOWA cells than in cell lines from other species. Deletion mutant analysis of the LTR of a PERV-NIH isolate identified regions that transactivate or repress transcription depending on the cell type.

scholarly journals Host Gene Regulation by Transposable Elements: The New, the Old and the Ugly

Viruses ◽  
2020 ◽  
Vol 12 (10) ◽  
pp. 1089 ◽  
Author(s):  
Rocio Enriquez-Gasca ◽  
Poppy A. Gould ◽  
Helen M. Rowe
Keyword(s):  
Gene Expression ◽  
Gene Regulation ◽  
Transposable Elements ◽  
Essential Gene ◽  
Expression Patterns ◽  
Genetic Material ◽  
Endogenous Retroviruses ◽  
Host Gene ◽  
New Genes ◽  
Host Genes

The human genome has been under selective pressure to evolve in response to emerging pathogens and other environmental challenges. Genome evolution includes the acquisition of new genes or new isoforms of genes and changes to gene expression patterns. One source of genome innovation is from transposable elements (TEs), which carry their own promoters, enhancers and open reading frames and can act as ‘controlling elements’ for our own genes. TEs include LINE-1 elements, which can retrotranspose intracellularly and endogenous retroviruses (ERVs) that represent remnants of past retroviral germline infections. Although once pathogens, ERVs also represent an enticing source of incoming genetic material that the host can then repurpose. ERVs and other TEs have coevolved with host genes for millions of years, which has allowed them to become embedded within essential gene expression programmes. Intriguingly, these host genes are often subject to the same epigenetic control mechanisms that evolved to combat the TEs that now regulate them. Here, we illustrate the breadth of host gene regulation through TEs by focusing on examples of young (The New), ancient (The Old), and disease-causing (The Ugly) TE integrants.

scholarly journals Signaling pathways and preimplantation development of mammalian embryos

FEBS Journal ◽  
2007 ◽  
Vol 274 (17) ◽  
pp. 4349-4359 ◽  
Author(s):  
Yong Zhang ◽  
Zhaojuan Yang ◽  
Ji Wu
Keyword(s):  
Signaling Pathways ◽  
Preimplantation Development ◽  
Mammalian Embryos

scholarly journals Human Endogenous Retrovirus HERV-K14 Families: Status, Variants, Evolution, and Mobilization of Other Cellular Sequences

2005 ◽  
Vol 79 (5) ◽  
pp. 2941-2949 ◽  
Author(s):  
Aline Flockerzi ◽  
Stefan Burkhardt ◽  
Werner Schempp ◽  
Eckart Meese ◽  
Jens Mayer
Keyword(s):  
Human Genome ◽  
Germ Line ◽  
Endogenous Retrovirus ◽  
Endogenous Retroviruses ◽  
Human Endogenous Retrovirus ◽  
Long Terminal Repeats ◽  
Essential Information ◽  
Human Endogenous Retroviruses ◽  
Consensus Sequences

ABSTRACT The human genome harbors many distinct families of human endogenous retroviruses (HERVs) that stem from exogenous retroviruses that infected the germ line millions of years ago. Many HERV families remain to be investigated. We report in the present study the detailed characterization of the HERV-K14I and HERV-K14CI families as they are represented in the human genome. Most of the 68 HERV-K14I and 23 HERV-K14CI proviruses are severely mutated, frequently displaying uniform deletions of retroviral genes and long terminal repeats (LTRs). Both HERV families entered the germ line ∼39 million years ago, as evidenced by homologous sequences in hominoids and Old World primates and calculation of evolutionary ages based on a molecular clock. Proviruses of both families were formed during a brief period. A majority of HERV-K14CI proviruses on the Y chromosome mimic a higher evolutionary age, showing that LTR-LTR divergence data can indicate false ages. Fully translatable consensus sequences encoding major retroviral proteins were generated. Most HERV-K14I loci lack an env gene and are structurally reminiscent of LTR retrotransposons. A minority of HERV-K14I variants display an env gene. HERV-K14I proviruses are associated with three distinct LTR families, while HERV-K14CI is associated with a single LTR family. Hybrid proviruses consisting of HERV-K14I and HERV-W sequences that appear to have produced provirus progeny in the genome were detected. Several HERV-K14I proviruses harbor TRPC6 mRNA portions, exemplifying mobilization of cellular transcripts by HERVs. Our analysis contributes essential information on two more HERV families and on the biology of HERV sequences in general.

scholarly journals Genome-Wide Detection and Characterization of Endogenous Retroviruses in Bos taurus

2010 ◽  
Vol 84 (20) ◽  
pp. 10852-10862 ◽  
Author(s):  
Koldo Garcia-Etxebarria ◽  
Begoña Marina Jugo
Keyword(s):  
Phylogenetic Relationship ◽  
Germ Line ◽  
Bos Taurus ◽  
Gc Content ◽  
Endogenous Retroviruses ◽  
Long Terminal Repeats ◽  
Multiple Methods ◽  
Bioinformatic Tools ◽  
Genome Wide

ABSTRACT Endogenous retroviruses (ERVs) are the proviral phase of exogenous retroviruses that become integrated into a host germ line. They can play an important role in the host genome. Bioinformatic tools have been used to detect ERVs in several vertebrates, primarily primates and rodents. Less information is available regarding ERVs in other mammalian groups, and the source of this information is basically experimental. We analyzed the genome of the cow (Bos taurus) using three different methods. A BLAST-based method detected 928 possible ERVs, LTR_STRUC detected 4,487 elements flanked by long terminal repeats (LTRs), and Retrotector detected 9,698 ERVs. The ERVs were not homogeneously distributed across chromosomes; the number of ERVs was positively correlated with chromosomal size and negatively correlated with chromosomal GC content. The bovine ERVs (BoERVs) were classified into 24 putative families, with 20 of them not previously described. One of these new families, BoERV1, was the most abundant family and appeared to be specific to ruminants. An analysis of representatives of ERV families from rodents, primates, and ruminants showed a phylogenetic relationship following their hosts' relationships. This study demonstrates the importance of using multiple methods when trying to identify new ERVs and shows that the number of bovine ERV families is not as limited as previously thought.

scholarly journals Functional evaluation of transposable elements as enhancers in mouse embryonic and trophoblast stem cells

eLife ◽  
2019 ◽  
Vol 8 ◽  
Author(s):  
Christopher D Todd ◽  
Özgen Deniz ◽  
Darren Taylor ◽  
Miguel R Branco
Keyword(s):  
Stem Cells ◽  
Gene Regulation ◽  
Transposable Elements ◽  
Specific Gene ◽  
Functional Evaluation ◽  
Mouse Development ◽  
Trophoblast Stem Cells ◽  
Trophoblast Stem ◽  
Gene Regulatory ◽  
Early Mouse

Transposable elements (TEs) are thought to have helped establish gene regulatory networks. Both the embryonic and extraembryonic lineages of the early mouse embryo have seemingly co-opted TEs as enhancers, but there is little evidence that they play significant roles in gene regulation. Here we tested a set of long terminal repeat TE families for roles as enhancers in mouse embryonic and trophoblast stem cells. Epigenomic and transcriptomic data suggested that a large number of TEs helped to establish tissue-specific gene expression programmes. Genetic editing of individual TEs confirmed a subset of these regulatory relationships. However, a wider survey via CRISPR interference of RLTR13D6 elements in embryonic stem cells revealed that only a minority play significant roles in gene regulation. Our results suggest that a subset of TEs are important for gene regulation in early mouse development, and highlight the importance of functional experiments when evaluating gene regulatory roles of TEs.

scholarly journals How Well Does Evolution Explain Endogenous Retroviruses?—A Lakatosian Assessment

Viruses ◽  
2021 ◽  
Vol 14 (1) ◽  
pp. 14
Author(s):  
Ruben N. Jorritsma
Keyword(s):  
Ad Hoc ◽  
Scientific Research ◽  
Hard Core ◽  
Research Programme ◽  
Early History ◽  
Endogenous Retroviruses ◽  
Long Terminal Repeats ◽  
Research Programmes ◽  
History Of ◽  
Protective Belt

One of the most sophisticated philosophies of science is the methodology of scientific research programmes (MSRP), developed by Imre Lakatos. According to MSRP, scientists are working within so-called research programmes, consisting of a hard core of fixed convictions and a flexible protective belt of auxiliary hypotheses. Anomalies are accommodated by changes to the protective belt that do not affect the hard core. Under MSRP, research programmes are appraised as ‘progressive’ if they successfully predict novel facts but are judged as ‘degenerative’ if they merely offer ad hoc solutions to anomalies. This paper applies these criteria to the evolutionary research programme as it has performed during half a century of ERV research. It describes the early history of the field and the emergence of the endogenization-amplification theory on the origins of retroviral-like sequences. It then discusses various predictions and postdictions that were generated by the programme, regarding orthologous ERVs in different species, the presence of target site duplications and the divergence of long terminal repeats, and appraises how the programme has dealt with data that did not conform to initial expectations. It is concluded that the evolutionary research programme has been progressive with regard to the issues here examined.

Eggs, embryos and the evolution of imprinting: insights from the platypus genome

2009 ◽  
Vol 21 (8) ◽  
pp. 935 ◽  
Author(s):  
Marilyn B. Renfree ◽  
Anthony T. Papenfuss ◽  
Geoff Shaw ◽  
Andrew J. Pask
Keyword(s):  
Genomic Imprinting ◽  
Large Scale ◽  
Strong Support ◽  
Gene Clusters ◽  
Host Defence ◽  
Long Terminal Repeats ◽  
Repeat Elements ◽  
Platypus Genome ◽  
Dna Elements ◽  
Genome Analyses

Genomic imprinting is widespread in eutherian and marsupial mammals. Although there have been many hypotheses to explain why genomic imprinting evolved in mammals, few have examined how it arose. The host defence hypothesis suggests that imprinting evolved from existing mechanisms within the cell that act to silence foreign DNA elements that insert into the genome. However, the changes to the mammalian genome that accompanied the evolution of imprinting have been hard to define due to the absence of large-scale genomic resources from all extant classes. The recent release of the platypus genome sequence has provided the first opportunity to make comparisons between prototherian (monotreme, which show no signs of imprinting) and therian (marsupial and eutherian, which have imprinting) mammals. We compared the distribution of repeat elements known to attract epigenetic silencing across the genome from monotremes and therian mammals, particularly focusing on the orthologous imprinted regions. Our analyses show that the platypus has significantly fewer repeats of certain classes in the regions of the genome that have become imprinted in therian mammals. The accumulation of repeats, especially long-terminal repeats and DNA elements, in therian imprinted genes and gene clusters therefore appears to be coincident with, and may have been a potential driving force in, the development of mammalian genomic imprinting. Comparative platypus genome analyses of orthologous imprinted regions have provided strong support for the host defence hypothesis to explain the origin of imprinting.

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