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Coren LV, Nagashima K, Ott DE. A PLPPV sequence in the p8 region of Gag provides late domain function for mouse mammary tumor virus. Virology 2019; 535:272-278. [PMID: 31357166 PMCID: PMC6952571 DOI: 10.1016/j.virol.2019.07.015] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2019] [Revised: 07/17/2019] [Accepted: 07/18/2019] [Indexed: 02/07/2023]
Abstract
The late (L) domain sequence used by mouse mammary tumor virus (MMTV) remains undefined. Similar to other L domain-containing proteins, MMTV p8 and p14NC proteins are monoubiquitinated, suggesting L domain function. Site-directed mutagenesis of p8, PLPPV, and p14NC, PLPPL, sequences in MMTV Gag revealed a requirement only for the PLPPV sequence in virion release in a position-dependent manner. Electron microscopy of a defective Gag mutant confirmed an L domain budding defect morphology. The equine infectious anemia virus (EIAV) YPDL core L domain sequence and PLPPV provided L domain function in reciprocal MMTV and EIAV Gag exchange mutants, respectively. Alanine scanning of the PLPPV sequence revealed a strict requirement for the valine residue but only minor requirements for any one of the other residues. Thus, PLPPV provides MMTV L domain function, representing a fourth type of retroviral L domain that enables MMTV Gag proteins to co-opt cellular budding pathways for release.
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Affiliation(s)
- Lori V Coren
- AIDS and Cancer Virus Program, National Cancer Institute at Frederick, Frederick, MD, 21702-1201, USA.
| | - Kunio Nagashima
- Advanced Technology Program, National Cancer Institute at Frederick, Frederick, MD, 21702-1201, USA
| | - David E Ott
- AIDS and Cancer Virus Program, National Cancer Institute at Frederick, Frederick, MD, 21702-1201, USA
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Nabarra B, Desaymard C, Waché AC, Papiernik M. Mouse mammary tumor virus production by thymic epithelial cells in vivo. Eur J Immunol 1996; 26:2724-30. [PMID: 8921961 DOI: 10.1002/eji.1830261126] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Exogenous mouse mammary tumor viruses (MMTV) replicate in the mammary glands of infected females, and so infect the suckling pups. We have previously shown that the virus is rapidly disseminated to all the lymphoid organs, including the thymus. The present electron microscope immunohistochemical study describes the viral production site in the thymus. Viral buds and viral proteins were restricted to the thymus medullary epithelial cells. MMTV-encoded proteins were identified on the free viral particles and on the budding ones, the ribosomes, the membrane of the endoplasmic reticulum, and on the membrane of the medullary type II epithelial cell vacuolar network. The thymus medullary epithelial cells can thus integrate the virus and allow viral replication. The results support earlier results indicating that in some experimental conditions, epithelial cells may be involved in MMTV-induced negative selection by showing that thymic epithelial cells do express MMTV-encoded proteins.
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Affiliation(s)
- B Nabarra
- U.345 INSERM, Institut Necker, Paris, France
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Tsubura A, Shikata N, Hilgers J, Zotter S, Tanaka H, Morii S. Immunoelectron microscopic localization of mammary tumor virus (MTV) antigens in normal and cancerous mammary glands of mice. Microbiol Immunol 1987; 31:665-74. [PMID: 2830473 DOI: 10.1111/j.1348-0421.1987.tb03127.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Peroxidase-labeled Fab' fragments of rabbit antisera against gp52 (major envelope protein) and A-particles of mammary tumor virus (MTV) were prepared and used for investigation by immunoelectron microscopy of the replication cycle of MTV-specific envelope and core antigens in normal and malignant mammary gland cells of female mice. The specificity of the antisera was proven by absorption tests and lack of reactivity to MTV-free mammary tissues. Periodate-lysine-paraformaldehyde (PLP) fixation sufficiently preserved the antigenicity of gp52, while Zamboni's fixative was useful to preserve the core antigen. Saponin pretreatment was necessary to reveal the intracellular antigen of A particles but had no influence on gp52. In addition to its presence at the envelope of D particles, gp52 was clearly associated with the biomembrane system, including the nuclear membrane, endoplasmic reticulum, Golgi apparatus and plasma membrane independent of the presence of virus particles. In mammary tumors, a significant level of gp52 antigen was often expressed on the entire cell surface membrane. In contrast, it was localized only to the apical plasma membrane in normal mammary gland cells. A particle antigens were confined to the intracytoplasmic A particles, usually visible as clusters, and to the inner part of B particles. These ultrastructural findings support the available biochemical data on the morphogenesis of MTV particles.
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MESH Headings
- Animals
- Antigens, Neoplasm/analysis
- Antigens, Neoplasm/immunology
- Antigens, Viral, Tumor/analysis
- Female
- Mammary Glands, Animal/immunology
- Mammary Glands, Animal/microbiology
- Mammary Neoplasms, Experimental/immunology
- Mammary Neoplasms, Experimental/microbiology
- Mammary Tumor Virus, Mouse/immunology
- Mammary Tumor Virus, Mouse/ultrastructure
- Mice
- Mice, Inbred Strains
- Virus Replication
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Affiliation(s)
- A Tsubura
- Department of Pathology, Kansai Medical University, Osaka
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Sarkar NH, Racevskis J. Expression and disposition of the murine mammary tumor virus (MuMTV) envelope gene products by murine mammary tumor cells. Virology 1983; 126:279-300. [PMID: 6302986 DOI: 10.1016/0042-6822(83)90479-8] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Three murine mammary tumor virus (MuMTV)-producing epithelial cell lines derived from murine mammary tumors were examined in order to identify the MuMTV-specific cell surface antigens and their distribution on the cell surface, to study the kinetics of the MuMTV envelope precursor processing, virus assembly, and release, and to characterize the soluble MuMTV antigens that are shed into culture medium. Cell surface labeling experiments showed that only the mature MuMTV envelope glycoproteins gp52 and gp36 were exposed on the cell surface, and that gp52 was more abundant than gp36. In cells producing large quantities of MuMTV, expression of gp52 on the cell surface was shown by immunoelectron microscopy to be localized predominantly on the surface of budding virions and not on smooth areas of the cell surface where virus was not budding. The cell surface associated gp36 was found not to be incorporated into budding virions. A few cells in all three cell lines were found to produce only a few or no MuMTV particles and in these cells, unlike in the high virus-producing cells, considerable quantities of gp52 were expressed on the surface membrane. All three cell lines were found to shed large amounts of the MuMTV env precursor polyprotein as well as the mature non-virion-associated glycoprotein, gp52, into the culture medium. The envelope precursor protein (P75env) that was shed into the culture medium was found to differ from the predominant form of the cellular env precursor (Pr70env) in that (1) P75env migrated with an apparent higher molecular weight than Pr70env in SDS gels; (2) Pr70env contained only the core oligosaccharide, whereas P75env contained fucose in addition to the core sugars; (3) two-dimensional gel electrophoretic analysis showed that Pr70env could be resolved into three to four components migrating in the basic region of the isoelectric focussing gel (pH 7-8), whereas P75env was resolved into 9-13 components migrating in a more acidic region of the gel (pH 5-7). The molecular structure of the exfoliated gp52 was found to be similar to that of the gp52 that was incorporated into the virions although the virion-associated gp52 was not the source of the gp52 in the medium. Our quantitative pulse-chase studies suggest that of the two populations of MuMTV env precursors that are present in MuMTV-producing cells, only Pr70env is processed intracellularly to give rise to the mature MuMTV envelope proteins gp52 and gp36.
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Callis AH, Ritzi EM. Detection and characterization of mouse mammary tumor virus cell surface antigens: estimation of antigen abundance by protein A assay. J Virol 1980; 35:876-87. [PMID: 6252344 PMCID: PMC288881 DOI: 10.1128/jvi.35.3.876-887.1980] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Antisera against the following mouse mammary tumor virus (MMTV) structural proteins were used to detect MMTV cell surface antigens: (i) the 27,000-dalton nucleoid protein, p27; (ii) the 36,000-dalton envelope glycoprotein, gp36; and (iii) the 52,000-dalton exterior envelope glycoprotein, gp52. We report here the development of an adherent-cell isotopic staphylococcal protein A (SPA) test (ISPAT) for MMTV structural proteins which allows for the detection of an MMTV membrane-associated antigen as well as an estimate of its relative abundance on the cell surface. This test demonstrated that the gp52 was the predominant MMTV cell surface antigen detected on both C3H and GR mouse mammary tumor cells. In a comparative study with anti-gp52 and anti-gp36 sera, SPA-specific binding with anti-gp36 serum was found to be only 5 to 6% of that obtained for the external virion glycoprotein, gp52. Both direct and indirect ISPAT indicated the presence of a low but detectable number of gp36 determinants on GR-MMTV cells; however, these gp36 determinants, unlike gp52 determinants, appeared to be exposed by the fixation procedure used. Only 0.9 to 1.1% of the gp52-specific binding was detected when anti-gp36 serum was allowed to react with viable cells. The binding of [125I]SPA achieved with anti-p27 serum was even less than that detected with gp36-directed reagents, indicating that p27 is not a cell surface antigen. The use of fluoresceinated SPA further demonstrated that p27 and gp36 reactivity was only associated with a small number of cells in each of the mammary cultures tested. When N-[4-(5-nitro-2-furyl)-2-thiazoly]-formamide-induced C3H bladder tumor cells were subjected to a gp52-directed ISPAT, the failure to detect gp52-specific binding demonstrated the specificity of this assay for MMTV gp52-expressing cells. In addition to detecting and characterizing MMTV cell surface antigens, the newly developed adherent cell assay could measure changes in the abundance of cell surface gp52. When dexamethasone-treated and untreated GR cells were compared, measurements of gp52-specific SPA binding indicated that dexamethasone stimulation leads to a 12.2-fold increase in the amount of cell surface gp52 detected.
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Tanaka H. Precursor-product relationship between nonglycosylated polypeptides of A and B particles of mouse mammary tumor virus. Virology 1977; 76:835-50. [PMID: 65829 DOI: 10.1016/0042-6822(77)90263-x] [Citation(s) in RCA: 35] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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Sheffield JB. Membrane alterations which accompany MuMTV maturation. I. Studies by freeze-cleave techniques. Virology 1974; 57:287-90. [PMID: 4362027 DOI: 10.1016/0042-6822(74)90130-5] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
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11
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Rühland D, Fasske E, Fetting R, Themann H. [Electronmicroscopic observations on mouse mammary tumor virus (MTV) with special regard to the extrusion of A-particles]. ZEITSCHRIFT FUR KREBSFORSCHUNG UND KLINISCHE ONKOLOGIE. CANCER RESEARCH AND CLINICAL ONCOLOGY 1973; 79:309-18. [PMID: 4355001 DOI: 10.1007/bf00304025] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
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Tanaka H, Tamura A, Tsujimura D. Properties of the intracytoplasmic A particles purified from mouse tumors. Virology 1972; 49:61-78. [PMID: 4114180 DOI: 10.1016/s0042-6822(72)80007-2] [Citation(s) in RCA: 39] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
MESH Headings
- Animals
- Antigens, Viral/analysis
- Centrifugation, Density Gradient
- Cytoplasm/microbiology
- Female
- Gammaretrovirus/analysis
- Gammaretrovirus/immunology
- Gammaretrovirus/isolation & purification
- Immunodiffusion
- Immunoelectrophoresis
- Inclusion Bodies, Viral
- Leukemia, Experimental/immunology
- Leukemia, Experimental/microbiology
- Leukemia, Experimental/pathology
- Mammary Neoplasms, Experimental/immunology
- Mammary Neoplasms, Experimental/microbiology
- Mammary Neoplasms, Experimental/pathology
- Mice
- Mice, Inbred Strains
- Microscopy, Electron
- Phosphotungstic Acid
- RNA, Viral/analysis
- Staining and Labeling
- Viral Proteins/analysis
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Morgan C. The use of ferritin-conjugated antibodies in electron microscopy. INTERNATIONAL REVIEW OF CYTOLOGY 1972; 32:291-326. [PMID: 4556298 DOI: 10.1016/s0074-7696(08)60343-5] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
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15
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Shigematsu T, Priori ES, Dmochowski L, Wilbur JR. Immunoelectron microscopic studies of type C virus particles in ESP-1 and HEK-1-HRLV cell lines. Nature 1971; 234:412-4. [PMID: 4333967 DOI: 10.1038/234412a0] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
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16
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Okano H. Distribution of viral antigen in mouse mammary tumor cells as revealed by ferritin antibody conjugate technique. ACTA PATHOLOGICA JAPONICA 1971; 21:57-66. [PMID: 5110008 DOI: 10.1111/j.1440-1827.1971.tb00109.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
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17
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Miroff G, Lamberson HV. The distribution of the mouse mammary tumor agent and its antigenicity in milk. Int J Cancer 1970; 5:136-46. [PMID: 4313229 DOI: 10.1002/ijc.2910050118] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
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18
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Micheel B, Bierwolf D. Demonstration of Graffi virus-induced surface antigens of leukemia cells by indirect immunoferritin technique. Exp Cell Res 1969; 54:268-71. [PMID: 4180463 DOI: 10.1016/0014-4827(69)90249-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
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