Endogenous mammary tumour virus DNA varies among wild mice and segregates during inbreeding

Cohen, J.; Varmus, Harold

doi:10.1038/278418a0

Cited by 201 publications

(123 citation statements)

References 34 publications

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“…The present data are in good agreement with the results obtained by Cohen & Varmus (1979) concerning the variability of sequences of endogenous mammary tumour retroviruses (MMTV) among wild and laboratory populations of mice. The completeness of the analogy is supported also by finding the population of wild mice without endogenous MMTV in their genomes.…”

Section: Discussionsupporting

confidence: 82%

Variety of Endogenous Proviruses in the Genomes of Chickens of Different Breeds

Gudkov

Obukh

Serov

et al. 1981

Journal of General Virology

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SUMMARYWe have compared endogenous proviruses in DNA of chickens of 11 breeds by means of Southern's technique. Many of the endogenous virus loci found were missing from the genomes of the extensively studied white leghorn chickens, although some of the proviruses and especially ev-I appeared to be widely spread among different chickens. Most of the proviruses were similar to Rous-associated virus (RAV-O) as judged by the EcoRI digestion patterns. Several genetically different proviruses were found in the DNA of 28 brown leghorns. They contain neither ev-1 provirus in their genome, nor any other one common for all individuals. All four Italian partridge-coloured chickens examined appeared to be free from ALV-related sequences in their DNA showing the possibility of normal life without known endogenous proviruses. Possible causes of inter-breed differences of chicken endogenous proviruses are discussed.

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Section: Discussionsupporting

confidence: 82%

Variety of Endogenous Proviruses in the Genomes of Chickens of Different Breeds

Gudkov

Obukh

Serov

et al. 1981

Journal of General Virology

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“…Marked strain-specific differences in copy number and insertion sites have been found for endogenous mammary tumor virus proviral DNA (15,20). In the case of the endogenous murine leukemia viruses, DNAs of different inbred mouse strains showed similar EcoRI restriction patterns, although each strain had minor characteristic differences (3,42).…”

Section: Discussionmentioning

confidence: 99%

Intracisternal A-particle genes in Mus musculus: a conserved family of retrovirus-like elements.

Kuff¹,

Smith²,

Lueders³

1981

Mol. Cell. Biol.

100

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The structural organization of intracisternal A-particle genes has been studied, using isolates from a mouse gene library in X phage Charon 4A. The predominant gene form among the isolates was 7.3 kilobases (kb) in length. R-loops between the 7-kb (35S) A-particle genomic ribonucleic acid and several of these genes were colinear, with no visible evidence of intervening deoxyribonucleic acid sequences. One recombinant was found with an A-particle gene that contained a 1.7-kb deletion. Using the deletion as a reference, the deoxyribonucleic acid and ribonucleic acid homology regions were localized with respect to one another and to the restriction map: the 5' terminus of the ribonucleic acid was several hundred base pairs within the 5' end of the deoxyribonucleic acid homology region. Restriction endonuclease fragments encompassing the 5' and 3' regions of one 7.3-kb gene were separately subcloned into pBR322. Heteroduplexes between the two subclones revealed an approximately 300-base pair segment of terminally redundant sequences. The cloned 3' fragment hybridized with restriction fragments from the 5' end of several other A-particle genes, demonstrating the presence of common (though not necessarily identical) terminally repeated sequences. A-particle genes varied in the occurrence of specific restriction sites at characteristic internal loci. However, heteroduplexes between several variant 7.3-kb genes showed continuous homology regions even when spread under stringent hybridization conditions. The relative abundance of restriction site variants was highly conserved in 12 laboratory strains of Mus musculus, in embryonic and adult tissues of a single inbred strain, and in the SC-1 cell line of feral mouse origin, but appeared to differ in a feral Japanese substrain, Mus musculus molossinus. Some evidence suggests that subsets of A-particle genes may have similar flanking sequences. The results are discussed in terms of the evolution of this multigene family.

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“…This genus includes Jaagsiekte sheep retrovirus (JSRV), the closely related enzootic nasal tumor virus (ENTV), and mouse mammary tumor virus (MMTV), all of which are oncogenic (17,18) and have endogenous as well as exogenous members (19,20). Closely related to the betaretroviruses are the numerous betaretrovirus-like endogenous retroviruses (ERVs) that have colonized the genomes of mammals, including the human endogenous retroviruses (HERVs) of the HERV-K(HML-2) group, members of which are estimated to have first infected our ancestors at least 34 million years ago (mya), with new rounds of infection occurring as recently as 200,000 years ago or less (21)(22)(23)(24).…”

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confidence: 99%

Betaretroviral Envelope Subunits Are Noncovalently Associated and Restricted to the Mammalian Class

Henzy

Coffin

2013

J Virol

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The structure of the transmembrane subunit (TM) of the retroviral envelope glycoprotein (Env) is highly conserved among most retrovirus genera and includes a pair of cysteines that forms an intramolecular disulfide loop within the ectodomain. Alpha-, gamma-, and deltaretroviruses have a third cysteine, adjacent to the loop, which forms a disulfide bond between TM and the surface subunit (SU) of Env, while lentiviruses, which have noncovalently associated subunits, lack this third cysteine. The Betaretrovirus genus includes Jaagsiekte sheep retrovirus (JSRV) and mouse mammary tumor virus (MMTV), as well as many endogenous retroviruses. Envelope subunit association had not been characterized in the betaretroviruses, but lack of a third cysteine in the TM ectodomain suggested noncovalently associated subunits. We tested the Env proteins of JSRV and MMTV, as well as human endogenous retrovirus K (HERV-K)108 -a betaretrovirus-like human endogenous retrovirus-for intersubunit bonding and found that, as in the lentiviruses, the Env subunits lack an intersubunit disulfide bond. Since these results suggest that the number of cysteines in the TM loop region readily distinguishes between covalent and noncovalent structure, we surveyed endogenous retroviral TM sequences in the genomes of vertebrates represented in public databases and found that (i) retroviruses with noncovalently associated subunits have been present during all of anthropoid evolution and (ii) the noncovalent env motif is limited to mammals, while the covalent type is found among five vertebrate classes. We discuss implications of these findings for retroviral evolution, cross-species transmissions, and recombination events involving the env gene. R etrovirus infection is mediated by the envelope (Env) glycoprotein, which is a class I viral fusion protein (VFP) in all of the orthoretroviral genera except the epsilonretroviruses. Class I VFPs are synthesized as precursors that trimerize in the endoplasmic reticulum and are cleaved by cellular furin in the late Golgi apparatus to generate two subunits: a surface subunit (SU), which interacts with the receptor on target cells, and a transmembrane subunit (TM), which mediates fusion and is anchored in the viral envelope near its C terminus. After cleavage, SU and TM remain associated either noncovalently or via an intersubunit disulfide bond (1-3, 82, 83), resulting in trimers of heterodimers that traffic to the cell's plasma membrane to become part of the viral envelope when newly synthesized particles bud from the cell (4).During infection, the fusion subunits of class I VFPs go through a series of conformational changes that lead from a metastable to a stable state. The first conformational change, which occurs upon binding of SU to the receptor, exposes a hydrophobic region at the N terminus of TM-the fusion peptide-which inserts into the plasma membrane of the target cell. This step then triggers the formation by TM of a highly stable six-helix bundle, a trimeric hairpin structure built around alpha-helic...

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Endogenous mammary tumour virus DNA varies among wild mice and segregates during inbreeding

Cited by 201 publications

References 34 publications

Variety of Endogenous Proviruses in the Genomes of Chickens of Different Breeds

Variety of Endogenous Proviruses in the Genomes of Chickens of Different Breeds

Intracisternal A-particle genes in Mus musculus: a conserved family of retrovirus-like elements.

Betaretroviral Envelope Subunits Are Noncovalently Associated and Restricted to the Mammalian Class

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