Mouse mammary tumor virus
| Mouse mammary tumor virus | |
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Virus classification
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| (unranked): | Virus |
| Realm: | Riboviria |
| Kingdom: | Pararnavirae |
| Phylum: | Artverviricota |
| Class: | Revtraviricetes |
| Order: | Ortervirales |
| Family: | Retroviridae |
| Genus: | Betaretrovirus |
| Species: | Mouse mammary tumor virus
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Mouse mammary tumor virus(MMTV) is a milk-transmittedretroviruslike theHTLviruses,HIviruses, andBLV.It belongs to the genusBetaretrovirus.MMTV was formerly known asBittner virus,and previously the "milk factor", referring to the extra-chromosomal vertical transmission ofmurinebreast cancer by adoptive nursing, demonstrated in 1936, byJohn Joseph Bittnerwhile working at theJackson Laboratoryin Bar Harbor, Maine. Bittner established the theory that a cancerous agent, or "milk factor", could be transmitted by cancerous mothers to young mice from a virus in their mother's milk.[1][2]The majority of mammary tumors in mice are caused by mouse mammary tumor virus.
Infection and life cycle
[edit]Several mouse strains carry the virus endogenously, but it is alsotransmitted verticallyvia milk from mother to pup. It is contained as a DNAprovirusintegrated in the DNA of milklymphocytes.The viruses become transported through the gastrointestinal tract to thePeyer's patcheswhere they infect the new host'smacrophages,and then lymphocytes.[citation needed]
The mouse mammary tumor virus (MMTV) has formerly been classified as a simpleretrovirus;however, it has recently been established, that MMTV encodes an extra self-regulatorymRNAexport protein, Rem, with resemblance to the human immunodeficiency virus (HIV)Revprotein, and is therefore the first complex murine retrovirus to be documented.[3][4]
MMTV codes for the retroviral structural genes and additionally for asuperantigen.This stimulatesT lymphocyteswith a certain type of V beta chain in theirT cell receptor,which in turn stimulatesB cellproliferation increasing the population of cells that can be infected.[5]During puberty, the virus enters the mammary glands with migrating lymphocytes and infects proliferating mammary gland epithelial cells.[6]
As a retrovirus the MMTV is able to insert its viral genome in the host genome. The virus RNA genome is reverse transcribed byreverse transcriptaseinto DNA. This DNA intermediate state of the virus is called theprovirus.When the virus DNA is inserted inside or even near a gene, it is able to change the expression of that gene and potentially produce anoncogenewhich might eventually develop into cancer.[7]The viral genome is able to cause cancer only if it alters the expression of an oncogene. If the viral genome is inserted in a "silent" region of the host genome then it is harmless or may cause other diseases. High levels of MMTV are expressed in lymphoid leukemias of mouse strain GR and DBA/2 which contain extra integrated MMTV proviruses. These leukemias are active when cells are transferred to other mice.[8]
When the virus genome is inserted inside the host genome it is then able to transcribe its own viral genes. In F. U. Reuss and J. M. Coffin (2000) experiments it is mentioned that the expression of the virus genome is activated by an enhancer element that is present in the U3 region of the long terminal repeat of the genome.[9]In addition the expression of the genome is activated specifically in the mammary gland cells.[9]Estrogenis able to further activate the expression of the viral genome.[7]The expression ofsaggene which is present in the provirus is responsible for the production of a superantigen.[6]
MMTV can be transferred either through an exogenous or endogenous route. If the virus is transferred exogenously, it is passed from the mother mouse to her pups through her milk.[10]
Alternatively, pups can be infectedverticallythrough endogenous infection, inheriting the virus directly from their mother in the germline. Mice that become infected in this way have higher rates of occurrence of tumors. A retrovirus is endogenous to its host once the proviral DNA is inserted into the chromosomal DNA. As a result, mice with endogenous MMTV have the virus's DNA in every cell of its body, as the virus is present in the DNA of the sperm or egg cell from which the animal is conceived.[citation needed]
Hormonal responsiveness of integrated MMTV DNA
[edit]Endogenous MMTV reacts to the whole range ofhormonesthat regulate normal mammary development and lactation, response has been demonstrated tosteroidhormones (androgens,glucocorticoidsandprogestins),[11]as well asprolactin.[12]
When the mouse reaches puberty the virus begins to express its messenger RNA in the estrogen sensitive tissues. As a result, after puberty all mammary cells will contain the active retrovirus and begin to replicate in the genome and express viral messenger RNA in all new mammary tissue cells.[10]
The MMTV promoter in models of human breast cancer
[edit]The LTR (long terminal repeat) of MMTV contains aglucocorticoidhormone response element.This glucocorticoid element is a promoter that is often used to construct mice which develop a breast cancer-like disease, because ananimal model system for breast cancerclose to the human disease is very much looked for.[citation needed]
The MMTV promoter is used in the PyMT model system ofmouse models of breast cancer metastasis.Here Py is the abbreviation of polyoma and MT is the abbreviation for middle T. There are more model systems of breast cancer which use the MMTV promoter. The polyoma middle T-antigen is taken from thepolyoma virus.The MMTV-PyMT model has been shown to be a reliable model of breast cancer metastasis.[13]In human breast cancer the polyoma middle T- antigen was not found.[14]
Notes
[edit]- ^Bittner, J. J. (1936). "Some Possible Effects of Nursing on the Mammary Gland Tumor Incidence in Mice".Science.84(2172): 162.Bibcode:1936Sci....84..162B.doi:10.1126/science.84.2172.162.PMID17793252.S2CID31163817.
- ^"Medicine: Cancer Virus".TIME magazine.18 March 1946. Archived fromthe originalon February 19, 2011.
- ^Mertz, JA; Simper, MS; Lozano, MM; Payne, SM; Dudley, JP (December 2005)."Mouse mammary tumor virus encodes a self-regulatory RNA export protein and is a complex retrovirus".Journal of Virology.79(23): 14737–47.doi:10.1128/JVI.79.23.14737-14747.2005.PMC1287593.PMID16282474.
- ^Indik, S; Gunzburg, WH; Salmons, B; Rouault, F (June 2005)."A novel, mouse mammary tumor virus encoded protein with Rev-like properties".Virology.337(1): 1–6.doi:10.1016/j.virol.2005.03.040.PMID15914215.
- ^Reuss, FU; Coffin, JM (July 1998)."Mouse mammary tumor virus superantigen expression in B cells is regulated by a central enhancer within the pol gene".Journal of Virology.72(7): 6073–82.doi:10.1128/JVI.72.7.6073-6082.1998.PMC110413.PMID9621071.
MMTV encodes a superantigen (Sag) that, when expressed on the surface of B cells or other antigen-presenting cells, activates a large number of T cells by interaction with specific T-cell receptor β chains. The resulting T-cell response in turn stimulates the infected B cells to proliferate and thus amplifies the number of virus-infected cells and potential target bystander cells
- ^abGolovkina, TV; Dudley, JP; Ross, SR (Sep 1, 1998)."B and T cells are required for mouse mammary tumor virus spread within the mammary gland".Journal of Immunology.161(5): 2375–82.doi:10.4049/jimmunol.161.5.2375.PMID9725233.S2CID26055839.
However, the ultimate targets of MMTV are mammary gland cells, which begin dividing during puberty...The infected lymphoid cells then bring virus to the cells of the developing mammary gland, thereby also allowing the virus to overcome its spatial problem... SAg activity is required for efficient viral infection of the mammary epithelial cells and consequent tumorigenesis...Thus, SAg-mediated stimulation of lymphoid cells is needed for their infection and for virus spread between mammary gland cells
- ^abOkeoma, Chioma M.; Lovsin, Nika; Peterlin, B. Matija; Ross, Susan R. (28 January 2007). "APOBEC3 inhibits mouse mammary tumour virus replication in vivo".Nature.445(7130): 927–930.Bibcode:2007Natur.445..927O.doi:10.1038/nature05540.PMID17259974.S2CID4316435.
- ^Michalides, Rob; Wagenaar, Els; Hilkens, John; Hilgers, Jo; Groner, Bernd; Hynes, Nancy (September 1982)."Acquisition of Proviral DNA of mouse mammary tumor virus in thymic leukemi cells from GR mice".Journal of Virology.43(3): 819–829.doi:10.1128/JVI.43.3.819-829.1982.PMC256192.PMID6292463.
- ^abReuss, F. U.; Coffin, J. M. (1 September 2000)."The Mouse Mammary Tumor Virus Transcription Enhancers for Hematopoietic Progenitor and Mammary Gland Cells Share Functional Elements".Journal of Virology.74(17): 8183–7.doi:10.1128/JVI.74.17.8183-8187.2000.PMC112353.PMID10933730.
- ^abMant, C; Gillett, C; D'Arrigo, C; Cason, J (Jan 5, 2004)."Human murine mammary tumour virus-like agents are genetically distinct from endogenous retroviruses and are not detectable in breast cancer cell lines or biopsies".Virology.318(1): 393–404.doi:10.1016/j.virol.2003.09.027.PMID14972564.
- ^Ham, J.; Thomson, A.; Needham, M.; Webb, P.; Parker, M. (1988)."Characterization of response elements for androgens, glucocorticoids and progestins in mouse mammary tumour virus".Nucleic Acids Research.16(12): 5263–76.doi:10.1093/nar/16.12.5263.PMC336766.PMID2838812.
- ^Muñoz, B.; Bolander Jr, F. F. (1989). "Prolactin regulation of mouse mammary tumor virus (MMTV) expression in normal mouse mammary epithelium".Molecular and Cellular Endocrinology.62(1): 23–29.doi:10.1016/0303-7207(89)90109-3.PMID2545485.S2CID40515926.
- ^Franci, C; Zhou, J; Jiang, Z; Modrusan, Z; Good, Z; Jackson, E; Kouros-Mehr, Hosein (2013)."Biomarkers of residual disease, disseminated tumor cells, and metastases in the MMTV-PyMT breast cancer model".PLOS ONE.8(3): e58183.Bibcode:2013PLoSO...858183F.doi:10.1371/journal.pone.0058183.PMC3592916.PMID23520493.
- ^Dankort DL, Muller WJ (2000). "Signal transduction in mammary tumorigenesis: a transgenic perspective".Oncogene.19(8): 1038–44.doi:10.1038/sj.onc.1203272.PMID10713687.
References
[edit]- Bhadra, Sanchita; Lozano, Mary M.; Payne, Shelley M.; Dudley, Jaquelin P. (1 January 2006)."Endogenous MMTV Proviruses Induce Susceptibility to Both Viral and Bacterial Pathogens".PLOS Pathogens.2(12): e128.doi:10.1371/journal.ppat.0020128.PMC1665650.PMID17140288.
- Cammack, Richard; Smith, Anthony Donald; Attwood, Teresa K.; et al. (eds.). "Bittner factor or Bittner particle former name for murine mammary tumour virus".Oxford Dictionary of Biochemistry and Molecular Biolog.p. 79.
- Courreges, M. C.; Burzyn, D.; Nepomnaschy, I.; Piazzon, I.; Ross, S. R. (31 January 2007)."Critical Role of Dendritic Cells in Mouse Mammary Tumor Virus In Vivo Infection".Journal of Virology.81(8): 3769–77.doi:10.1128/JVI.02728-06.PMC1866091.PMID17267484.
- Fernandez-Cobo, Mariana; Melana, Stella M; Holland, James F; Pogo, Beatriz GT (1 January 2006)."Transcription profile of a human breast cancer cell line expressing MMTV-like sequences".Infectious Agents and Cancer.1(1): 7.doi:10.1186/1750-9378-1-7.PMC1764410.PMID17173685.
- Indik, S. (1 August 2005)."Mouse Mammary Tumor Virus Infects Human Cells".Cancer Research.65(15): 6651–9.doi:10.1158/0008-5472.CAN-04-2609.PMID16061645.
- Indik, Stanislav; Günzburg, Walter H; Kulich, Pavel; Salmons, Brian; Rouault, Francoise (1 January 2007)."Rapid spread of mouse mammary tumor virus in cultured human breast cells".Retrovirology.4(1): 73.doi:10.1186/1742-4690-4-73.PMC2169256.PMID17931409.
- Lawson, JS; Günzburg, WH; Whitaker, NJ (June 2006). "Viruses and human breast cancer".Future Microbiology.1(1): 33–51.doi:10.2217/17460913.1.1.33.PMID17661684.
- Levine, Paul H.; Pogo, Beatriz G.-T.; Klouj, Afifa; Coronel, Stephanie; Woodson, Karen; Melana, Stella M.; Mourali, Nejib; Holland, James F. (15 August 2004). "Increasing evidence for a human breast carcinoma virus with geographic differences".Cancer.101(4): 721–6.doi:10.1002/cncr.20436.PMID15305401.S2CID42247400.
- Salmons, B; Lawson, JS; Gunzburg, WH (December 2014)."Recent developments linking retroviruses to human breast cancer: infectious agent, enemy within or both?".Journal of General Virology.95(12): 2589–93.doi:10.1099/vir.0.070631-0.PMID25217613.
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