Discovery of a Novel Murine Type C Retrovirus by Data Mining

Bromham, Lindell; Clark, Francis; McKee, Jeff J.

doi:10.1128/jvi.75.6.3053-3057.2001

Cited by 15 publications

(23 citation statements)

References 10 publications

(6 reference statements)

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“…Subsequently, several data-mining programs have been used to both identify novel ERV families, as well as validate earlier genetic analysis [1, 17–20]. As in the human genome, the three different classes of ERVs can be readily distinguished, and together make up close to 10% of their host’s genome (Fig.…”

Section: Distribution and Classes Of Ervs In The Mouse Genomementioning

confidence: 99%

Endogenous retroviruses

Stocking

Kozak

2008

Cell. Mol. Life Sci.

215

194

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Up to 10% of the mouse genome is comprised of endogenous retrovirus (ERV) sequences, and most represent the remains of ancient germ line infections. Our knowledge of the three distinct classes of ERVs is inversely correlated with their copy number, and their characterization has benefited from the availability of divergent wild mouse species and subspecies, and from ongoing analysis of the Mus genome sequence. In contrast to human ERVs, which are nearly all extinct, active mouse ERVs can still be found in all three ERV classes. The distribution and diversity of ERVs has been shaped by host-virus interactions over the course of evolution, but ERVs have also been pivotal in shaping the mouse genome by altering host genes through insertional mutagenesis, by adding novel regulatory and coding sequences, and by their co-option by host cells as retroviral resistance genes. We review mechanisms by which an adaptive coexistence has evolved. (Part of a Multi-author Review)

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Section: Distribution and Classes Of Ervs In The Mouse Genomementioning

confidence: 99%

Endogenous retroviruses

Stocking

Kozak

2008

Cell. Mol. Life Sci.

215

194

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“…In mice, eight families of ERVs, with a structure close to the integrated proviral form of exogenous retroviruses (gag-, pol-, and env-related regions bordered by two LTRs), have been described. Those with close exogenous relatives include type B proviruses related to the murine mammary tumor virus (6) and type C proviruses related to the Moloney murine leukemia virus (MLV), with the endogenous MLV, MuRRS, MuRVY, GLN, MuERVC, and MmERV family members (1,7,8). A family of sequences with no exogenous relatives, called IAPE (intracisternal A-particle sequences with an envelope gene), was also described (9).…”

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confidence: 99%

Syncytin-A and syncytin-B, two fusogenic placenta-specific murine envelope genes of retroviral origin conserved in Muridae

Dupressoír

Marceau

Vernochet

et al. 2005

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

326

234

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Recently, we and others have identified two human endogenous retroviruses that entered the primate lineage 25-40 million years ago and that encode highly fusogenic retroviral envelope proteins (syncytin-1 and -2), possibly involved in the formation of the placenta syncytiotrophoblast layer generated by trophoblast cell fusion at the materno-fetal interface. A systematic in silico search throughout mouse genome databases presently identifies two fully coding envelope genes, present as unique copies and unrelated to any known murine endogenous retrovirus, that we named syncytin-A and -B. Quantitative RT-PCR demonstrates placentaspecific expression for both genes, with increasing transcript levels in this organ from 9.5 to 14.5 days postcoitum. In situ hybridization of placenta cryosections further localizes these transcripts in the syncytiotrophoblast-containing labyrinthine zona. Consistently, we show that both genes can trigger cell-cell fusion in ex vivo transfection assays, with distinct cell type specificities suggesting different receptor usage. Genes orthologous to syncytin-A and -B and disclosing a striking conservation of their coding status are found in all Muridae tested (mouse, rat, gerbil, vole, and hamster), dating their entry into the rodent lineage Ϸ20 million years ago. Together, these data strongly argue for a critical role of syncytin-A and -B in murine syncytiotrophoblast formation, thus unraveling a rather unique situation where two pairs of endogenous retroviruses, independently acquired by the primate and rodent lineages, would have been positively selected for a convergent physiological role.endogenous retrovirus ͉ placenta ͉ syncytiotrophoblast ͉ rodent E ndogenous retroviruses (ERVs) are present in the genome of all vertebrates (1-3). They are most probably the genomic traces of germ-line infections by exogenous retroviruses having taken place during evolution. Over time, increase in their copy number has occurred, at least for some of them, via retrotransposition or germ-cell reinfection. This generated multigenic families containing a few to several hundred elements and now accounting for a substantial fraction of the genome [8% for the human (4) and 10% for the murine (5) genomes]. In mice, eight families of ERVs, with a structure close to the integrated proviral form of exogenous retroviruses (gag-, pol-, and env-related regions bordered by two LTRs), have been described. Those with close exogenous relatives include type B proviruses related to the murine mammary tumor virus (6) and type C proviruses related to the Moloney murine leukemia virus (MLV), with the endogenous MLV, MuRRS, MuRVY, GLN, MuERVC, and MmERV family members (1,7,8). A family of sequences with no exogenous relatives, called IAPE (intracisternal A-particle sequences with an envelope gene), was also described (9). Although some of these ERVs have accumulated mutations, deletions, and͞or truncations and would therefore require recombination with exogenous counterparts to generate replication-competent retroviruses, oth...

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“…Finally, the most diverse group of mouse ERVs belongs to the gammaretroviruses. Rather paradoxically, it includes both a very well-characterized family of elements, namely, the murine leukemia viruses (MLVs), and a series of little-studied elements, including murine retrovirus-related DNA sequences (30), murine retrovirus Y-associated element (13), MuERV-C (37), Mus musculus ERV (8), and murine retrovirus using tRNA Gln (GLN) (18,25). These are present at high copy numbers, with only the last two families showing copies with coding-competent env genes (reference 12 and data not shown).…”

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confidence: 99%

The GLN Family of Murine Endogenous Retroviruses Contains an Element Competent for Infectious Viral Particle Formation

Ribet

Harper

Esnault

et al. 2008

J Virol

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Several families of endogenous retroviruses (ERVs) have been identified in the mouse genome, in several instances by in silico searches, but for many of them it remains to be determined whether there are elements that can still encode functional retroviral particles. Here, we identify, within the GLN family of highly reiterated ERVs, one, and only one, copy that encodes retroviral particles prone to infection of mouse cells. We show that its envelope protein confers an ecotropic host range and recognizes a receptor different from mCAT1 and mSMIT1, the two previously identified receptors for other ecotropic mouse retroviruses. Electron microscopy disclosed viral particle assembly and budding at the cell membrane, as well as release of mature particles into the extracellular space. These particles are closely related to murine leukemia virus (MLV) particles, with which they have most probably been confused in the past. This study, therefore, identifies a new class of infectious mouse ERVs belonging to the family Gammaretroviridae, with one family member still functional today. This family is in addition to the two MLV and mouse mammary tumor virus families of active mouse ERVs with an extracellular life cycle.Complete sequencing of the mouse genome has led to the identification of multiple families of endogenous retroviruses (ERVs), each with a variable number of elements ranging from a few copies to several hundred (33; reviewed in references 6 and 20). These elements can now be classified according to their pol gene homology, and the resulting phylogenetic analysis recapitulates, in part, the diversity that can be found at the level of the present-day infectious retroviruses of animals. In the cases where functional copies have been identified and characterized, this classification can be further refined according to criteria unrelated to their sequences but involving both the site of assembly and the morphology of the associated virus-like particles. In fact, the latter classification corresponds to the historical one, essentially based on pioneering electron microscopic analyses of the A-, B-, C-, or epsilon-type virus-like particles that can be observed in mouse cells and tissues (5, 36; reviewed in reference 24). Along these lines, and as illustrated in Fig. 1B, the first significant fraction of the mouse ERVs belongs to the family Betaretroviridae and includes the endogenous mouse mammary tumor virus elements (ϳ10 copies in the C57BL/6 genome) and the highly reiterated Mus musculus type D/early transposon (MusD/ETn) ERVs (ϳ350 copies), whose particles have recently been demonstrated to assemble in a strictly intracellular location (28), as observed for type B/D retroviruses. A second large family of ERVs includes the intracisternal A-type particle (more than 1,000 copies) and intracisternal A-type particle-related, envelope-encoding elements (ϳ250 copies), which are also phylogenetically close to betaretroviruses but can be distinguished from the latter by the site of particle assembly, which is not within ...

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Discovery of a Novel Murine Type C Retrovirus by Data Mining

Cited by 15 publications

References 10 publications

Endogenous retroviruses

Endogenous retroviruses

Syncytin-A and syncytin-B, two fusogenic placenta-specific murine envelope genes of retroviral origin conserved in Muridae

The GLN Family of Murine Endogenous Retroviruses Contains an Element Competent for Infectious Viral Particle Formation

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