Virus Particles in Early Mouse Embryos2

Biczysko, W; Pieńkowski, Marek; Solter, Davor; Koprowski, Hilary

doi:10.1093/jnci/51.3.1041

Cited by 111 publications

(44 citation statements)

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“…Since IAPs are clearly retroviral entities, these results are consistent with the long-standing observation that EC cells are refractory to infection by a number of DNA and RNA viruses, including several retroviruses (10,11,32,38,41,42). Moreover, F9 cells have been shown, by a number of criteria, to resemble the embryonic ectoderm (9, 16) and, as has been shown previously, the ectoderm at this stage is virtually devoid of IAPs (6). However, in contrast to our results, Hojman-Montes de Oca et al (14) found that the EC cell lines PCC6 (nullipotent) and PCC3 (pluripotent) synthesized large amounts of IAP RNA.…”

Section: Discussionsupporting

confidence: 90%

Expression of the intracisternal A-particle is elevated during differentiation of embryonal carcinoma cells.

Howe¹,

Overton²

1986

Mol. Cell. Biol.

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Three cDNA clones coding for the 3' region of the intracisternal A-particle (IAP), a mouse endogenous retrovirus, were isolated during screening of a library for genes whose expression was modulated during the retinoic acid-induced differentiation of the embryonal carcinoma cell line F9 into parietal endoderm-like (PE-like) cells. In contrast to previously reported results, no IAP transcripts were detected in either F9 cells or two pluripotent cell lines tested. Instead, IAP transcripts as well as IAPs were abundant in the PE-like cells PYS-2 and F9AcCl 9 and in retinoic acid-induced F9 cells but not in the other differentiated cell types of teratocarcinoma origin which were examined. A comparison of the nucleotide sequences of the three IAP cDNA clones with a genomically integrated proviral sequence (MIA14) demonstrated heterogeneity in both length and sequence among the clones. The position of the poly(A) addition site was determined to be 15 nucleotides from the proposed poly(A) addition signal and to occur after the sequence CAGA, not CA, as previously proposed.Length heterogeneity was greatest in a region of TC repeats 80 base pairs 5' to the poly(A) addition site. Additionally, the putative TATAA box found in MIA14 was deleted in the cDNA clones and in the long terminal repeat regions from two other genomic clones examined. The heterogeneity evident among the cDNA clones further demonstrated that at least two distinct IAP genes are activated during differentiation. An analysis of the rate of transcription in isolated nuclei indicated that the activation of expression of IAP genes in PE-like cells is the result of transcriptional regulation. Together, these observations suggest that the modulation of IAP transcription is regulated autonomously rather than by the fortuitous integration of an IAP sequence adjacent to a developmentally regulated cellular gene.Analyses of gene regulation during early mammalian embryogenesis have been greatly aided by the availability of the murine embryonal carcinoma (EC) cell system, an in vitro model of early embryogenesis, and by the ability to clone genes that are differentially expressed during development. EC cells, derived from teratocarcinoma stem cells (19), share many antigenic and biochemical properties with ectoderm cells of the inner cell mass, including the ability to differentiate initially to endoderm cells (13,16,35). The F9 EC cell line, which is nullipotent and has a low frequency of spontaneous differentiation (5), has proven to be a particularly useful model, since these cells differentiate upon treatment with retinoic acid (RA) or RA plus dibutyryl cyclic AMP (dbcAMP) into cells that resemble the parietal endoderm (PE) of embryos. For instance, these PE-like cells synthesize and secrete the extracellular matrix components laminin, type IV collagen, entactin, and heparin sulfate proteoglycan (39, 40).To date, only a few molecular clones have been generated from either differentiated embryonic or teratocarcinomaderived cells. These include cDNA clones for ty...

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Section: Discussionsupporting

confidence: 90%

Expression of the intracisternal A-particle is elevated during differentiation of embryonal carcinoma cells.

Howe¹,

Overton²

1986

Mol. Cell. Biol.

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“…Although A-particles are quite abundant in preimplantation mouse embryos (7,8,13) and in certain mouse tumor cells (30), we have no idea of the fraction of transcriptionally active genes in these situations or whether any such genes are included among our isolates. A-particles from different tumors contain, in addition to 35S RNA, a variety of smaller but sequence-related RNA species: e.g., a 32S RNA is abundant in particles from neuroblastoma and MOPC-21 myeloma cells, whereas a 29S form predominates in MOPC-104E (36).…”

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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“…Intracisternal A-type particles (IAPs), of which two morphological subtypes have been distinguished (3,4), are the most prominent. Particles of one subtype, termed "small A particles" (3) or, more recently, "s-particles" to emphasize their distinctness (4), seem to be specific for early embryonic cells and form in large clusters in two-to eight-cell embryos but are absent or sparse at other stages (3)(4)(5)(6)(7). We will refer to these particles as IAP(E)s. The other subtype, designated "large A particles" by Chase and Pik6 (3), is morphologically very similar to the IAPs that are abundant in many mouse tumors including myelomas (8).…”

Section: Iap(s)] Using Cloned Fragments Of Iap Genes As Labeledmentioning

confidence: 99%

Amounts, synthesis, and some properties of intracisternal A particle-related RNA in early mouse embryos.

Pikó¹,

Hammons²,

Taylor³

1984

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

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Early mouse embryos express two morphological subtypes of intracisternal A-type particles, one resembling those occurring in mouse tumors (referred to as IAP) and the other apparently specific for early embryos [referred to as IAP(s)]. Using cloned fragments of IAP genes as labeled probes in dot-hybridization experiments, we detected IAP-related RNA sequences in mouse oocytes and preimplantation embryos. IAP RNA is relatively abundant in ovarian oocytes, is reduced in amount to l1/10th in the ovulated erg, and increases f100 times (from -1.3 x 103 to -1.5 x 10 molecules per embryo) between the one-cell stage and late blastocyst stage. Most of the IAP RNA consists of a single size class of about 5.4 kilobases, and a major fraction of this RNA is polyadenylylated. Quantitative considerations suggest that only a few percent of the IAP RNA in embryos are associated with particles. In two-cell embryos, the number of IAP RNA molecules is <1/10th the number of IAP(E) particles, suggesting that IAP(E) is genetically distinct from IAP and presumably represents a family of as yet unidentified retrovirus-like elements.Early mouse embryos regularly express several types of virus-like structures whose appearance is correlated with specific stages of development (for review, see refs. 1 and 2). Intracisternal A-type particles (IAPs), of which two morphological subtypes have been distinguished (3,4), are the most prominent. Particles of one subtype, termed "small A particles" (3) or, more recently, "s-particles" to emphasize their distinctness (4), seem to be specific for early embryonic cells and form in large clusters in two-to eight-cell embryos but are absent or sparse at other stages (3-7). We will refer to these particles as IAP(E)s. The other subtype, designated "large A particles" by Chase and Pik6 (3) (3,4). In this report, we will restrict the term UAP to this second type of A particle. The role of either subtype of A particle in embryo development is unclear at present, but there is evidence for the cell-surface expression of IAPrelated antigens in early embryonic cells (9, 10).The IAPs found in tumor cells have many properties resembling those of infectious retroviruses, but IAPs are genetically distinct from the mouse type B and type C viruses (11,12). IAPs have reverse transcriptase activity (13) and contain polyadenylylated RNA of 3.5 to 7 kilobases (kb) (14, 15), which codes for the major particle protein p73 (14). There are 1,000 TAP genes (provirus-like genetic elements) per haploid mouse genome (15)(16)(17), and genomic clones of several of these have been isolated and analyzed (15,18,19). The predominant gene form is 7 kb in length (18, 19), but shorter units with major deletions and substitutions also have been found (15,17). IAP genes are bordered by direct long terminal repeats (LTRs) of about 0.35 kb, which are similar in structure to the proviral LTRs of infectious retroviruses (20, 21). IAP gene insertions were found in two mutant mouse K light-chain genes (21) and in a cellular oncogene (22),...

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Virus Particles in Early Mouse Embryos2

Cited by 111 publications

References 0 publications

Expression of the intracisternal A-particle is elevated during differentiation of embryonal carcinoma cells.

Expression of the intracisternal A-particle is elevated during differentiation of embryonal carcinoma cells.

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

Amounts, synthesis, and some properties of intracisternal A particle-related RNA in early mouse embryos.

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