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{{Short description|Mouse with altered genomes}}
[[File:Knockout Mice5006-300.jpg|thumb|right|The genetically modified mouse in which a gene affecting hair growth has been knocked out (left) shown next to a normal lab mouse]]
A '''genetically modified mouse''', '''genetically engineered mouse model''' ('''GEMM''')<ref>{{cite journal |last1=Singh |first1=M. |last2=Murriel |first2=C. L. |last3=Johnson |first3=L. |title=Genetically Engineered Mouse Models: Closing the Gap between Preclinical Data and Trial Outcomes |journal=Cancer Research |date=16 May 2012 |volume=72 |issue=11 |pages=2695–2700 |doi=10.1158/0008-5472.CAN-11-2786|pmid=22593194 |doi-access=free }}</ref> or '''transgenic mouse''' is a [[house mouse|mouse]] (''Mus musculus'') that has had its [[genome]] altered through the use of [[genetic engineering]] techniques. Genetically modified mice are commonly used for research or as animal models of human diseases and are also used for research on genes. Together with [[patient-derived xenograft]]s (PDXs), GEMMs are the most common ''[[in vivo]]'' models in [[cancer research]]. The two approaches are considered complementary and may be used to recapitulate different aspects of disease.<ref>{{cite journal |last1=Abate-Shen |first1=C. |last2=Pandolfi |first2=P. P. |title=Effective Utilization and Appropriate Selection of Genetically Engineered Mouse Models for Translational Integration of Mouse and Human Trials |journal=Cold Spring Harbor Protocols |date=30 September 2013 |volume=2013 |issue=11 |pages=1006–1011 |doi=10.1101/pdb.top078774|pmid=24173311 |pmc=4382078 |doi-access=free }}</ref> GEMMs are also of great interest for [[drug development]], as they facilitate target validation and the study of response, resistance, toxicity and [[pharmacodynamics]].<ref>{{cite journal |last1=Sharpless |first1=Norman E. |last2=DePinho |first2=Ronald A. |title=The mighty mouse: genetically engineered mouse models in cancer drug development |journal=Nature Reviews Drug Discovery |date=September 2006 |volume=5 |issue=9 |pages=741–754 |doi=10.1038/nrd2110 |pmid=16915232 |s2cid=7254415 |url=https://www.nature.com/articles/nrd2110 |language=en |issn=1474-1784|url-access=subscription }}</ref>

==History==
In 1974 [[Beatrice Mintz]] and [[Rudolf Jaenisch]] created the first genetically modified animal by inserting a DNA virus into an early-stage mouse [[embryo]] and showing that the inserted genes were present in every cell.<ref>{{cite journal|doi=10.1073/pnas.71.4.1250|author1=Jaenisch, R.|author2=Mintz, B.|year=1974|title=Simian virus 40 DNA sequences in DNA of healthy adult mice derived from preimplantation blastocysts injected with viral DNA.|journal=Proc. Natl. Acad. Sci.|volume=71|issue=4|pages=1250–1254|pmid=4364530|pmc=388203|bibcode=1974PNAS...71.1250J|doi-access=free}}</ref> However, the mice did not pass the [[transgene]] to their offspring, and the impact and applicability of this experiment were, therefore, limited. In 1981 the laboratories of [[Frank Ruddle]]<ref>{{cite journal|author=Kucherlapati, Raju|author2=Leinwand, Leslie A.|year=2013|title=Frank Ruddle (1929–2013|journal=[[American Journal of Human Genetics]]|volume=92|issue=6|pages=839–840|doi=10.1016/j.ajhg.2013.05.012|pmid=24242788|pmc=3675234}}</ref> from [[Yale University]], Frank Costantini and Elizabeth Lacy from [[University of Oxford|Oxford]], and [[Ralph L. Brinster]] and Richard Palmiter in collaboration from the [[University of Pennsylvania]] and the [[University of Washington]] injected purified DNA into a [[Zygote|single-cell mouse embryo]] utilizing techniques developed by Brinster in the 1960s and 1970s, showing transmission of the genetic material to subsequent generations for the first time.<ref>{{cite journal|pages=1244–6|issue=4526|year=1981|pmid=6272397|doi=10.1126/science.6272397|volume=214|journal=Science|author2=Ruddle, F.|title=Integration and stable germ line transmission of genes injected into mouse pronuclei|author1=Gordon, J.|bibcode=1981Sci...214.1244G}}</ref><ref>{{cite journal|pages=92–4|issue=5836|year=1981| pmid = 6945481| doi = 10.1038/294092a0|volume=294|journal=Nature|author2=Lacy, E.|title=Introduction of a rabbit β-globin gene into the mouse germ line|author1=Costantini, F.|bibcode=1981Natur.294...92C|s2cid=4371351}}</ref><ref>{{cite journal|vauthors=Brinster R, Chen HY, Trumbauer M, Senear AW, Warren R, Palmiter RD|title=Somatic expression of herpes thymidine kinase in mice following injection of a fusion gene into eggs|doi=10.1016/0092-8674(81)90376-7|journal=Cell|volume=27|issue=1 Pt 2|pages=223–231|year=1981|pmid=6276022|pmc=4883678}}</ref> During the 1980s, Palmiter and Brinster developed and led the field of transgenesis, refining methods of [[germline]] modification and using these techniques to elucidate the activity and function of genes in a way not possible before their unique approach.<ref name="Hanahan">{{cite journal|doi=10.1101/gad.1583307|title=The origins of oncomice: a history of the first transgenic mice genetically engineered to develop cancer|journal=Genes Dev.|year=2007|volume=21|issue=18|pages=2258–2270|author1=Douglas Hanahan|author2=Erwin F. Wagner|author3=Richard D. Palmiter|url=http://genesdev.cshlp.org/content/21/18/2258.full.pdf+html|pmid=17875663|doi-access=free}}</ref>

==Methods==
There are two basic technical approaches to produce genetically modified mice. The first involves [[Microinjection#Pronuclear injection|pronuclear injection]], a technique developed and refined by [[Ralph L. Brinster]] in the 1960s and 1970s, into a single cell of the mouse embryo, where it will randomly integrate into the mouse genome.<ref>{{cite journal|doi=10.1073/pnas.77.12.7380|author=Gordon, J.W., Scangos, G.A, Plotkin, D.J., Barbosa, J.A. and Ruddle F.H.|year=1980|journal=Proc. Natl. Acad. Sci. USA|title=Genetic transformation of mouse embryos by microinjection of purified DNA|volume=77|issue=12|pages=7380–7384|pmid=6261253|pmc=350507|bibcode=1980PNAS...77.7380G|doi-access=free}}</ref> This method creates a [[transgenic]] mouse and is used to insert new genetic information into the mouse genome or to over-express [[endogenous]] genes. The second approach, pioneered by [[Oliver Smithies]] and [[Mario Capecchi]], involves modifying [[embryonic stem cells]] with a [[DNA construct]] containing DNA sequences [[Homology (biology)|homologous]] to the target gene. Embryonic stem cells that [[Genetic recombination|recombine]] with the genomic DNA are selected for and they are then injected into the mice [[blastocysts]].<ref>{{cite journal|vauthors=Thomas KR, Capecchi MR |year=1987|title=Site-directed mutagenesis by gene targeting in mouse embryo-derived stem cells|journal=Cell|pmid=2822260|volume=51|issue=3|pages=503–12|doi=10.1016/0092-8674(87)90646-5|s2cid=31961262}}</ref> This method is used to manipulate a single gene, in most cases [[gene knockout|"knocking out"]] the target gene, although increasingly more subtle and complex genetic manipulation can occur (e.g. humanisation of a specific protein, or only changing single [[nucleotides]]). A [[humanised mouse]] can also be created by direct addition of human genes, thereby creating a [[Murinae|murine]] form of [[human–animal hybrid]]. For example, genetically modified mice may be born with [[human leukocyte antigen]] genes in order to provide a more realistic environment when introducing human [[white blood cells]] into them in order to study [[immune system]] responses.<ref name=Yong>{{cite journal | vauthors = Yong KS, Her Z, Chen Q | title = Humanized Mice as Unique Tools for Human-Specific Studies | journal = Archivum Immunologiae et Therapiae Experimentalis | volume = 66 | issue = 4 | pages = 245–266 | date = August 2018 | pmid = 29411049 | pmc = 6061174 | doi = 10.1007/s00005-018-0506-x }}</ref> One such application is the identification of [[hepatitis C virus]] (HCV) peptides that bind to HLA, and that can be recognized by the human immune system, thereby potentially being targets for future vaccines against HCV.<ref>{{cite web|url=https://www.jax.org/strain/003475|website=The Jackson Laboratory|title=Mouse strain C57BL/6-Mcph1<sup>Tg(HLA-A2.1)1Enge</sup>|accessdate=2023-01-06}}</ref>

==Uses==
[[Image:GFP Mice 01.jpg|thumb|right|Transgenic mice expressing [[green fluorescent protein]], which glows green under blue light. The central mouse is [[wild-type]].]]
Genetically modified mice are used extensively in research as models of human disease.<ref>{{cite web|title=Background: Cloned and Genetically Modified Animals|date=April 14, 2005|publisher=Center for Genetics and Society|url=http://www.geneticsandsociety.org/article.php?id=386|access-date=July 11, 2010|archive-url=https://web.archive.org/web/20161123110939/http://geneticsandsociety.org/article.php?id=386|archive-date=November 23, 2016|url-status=dead}}</ref> Mice are a useful model for genetic manipulation and research, as their [[Tissue (biology)|tissues]] and [[Organ (anatomy)|organs]] are similar to that of a human and they carry virtually all the same genes that operate in humans.<ref name=":0">{{cite book|title=Transgenic Mouse|last=Hofker|first=Marten H.|publisher=Humana Press|year=2002|isbn=0-89603-915-3|location=Totowa, New Jersey|pages=[https://archive.org/details/transgenicmousem00mart/page/1 1]|author2=Deursen, Jan van|url-access=registration|url=https://archive.org/details/transgenicmousem00mart/page/1}}</ref> They also have advantages over other mammals, in regards to research, in that they are available in hundreds of genetically homogeneous strains.<ref name=":0"/> Also, due to their size, they can be kept and housed in large numbers, reducing the cost of research and experiments.<ref name=":0"/> Transgenic mice are found in two main models of either loss or gain of function. The most common type is loss of function mice or the [[knockout mouse]], where the activity of a single (or in some cases multiple) genes are removed or silenced. Gain of function mice, in other hand, overexpress a specific gene.<ref name=":2">{{Cite journal |last1=Lampreht Tratar |first1=Ursa |last2=Horvat |first2=Simon |last3=Cemazar |first3=Maja |date=2018-07-20 |title=Transgenic Mouse Models in Cancer Research |journal=Frontiers in Oncology |language=English |volume=8 |page=268 |doi=10.3389/fonc.2018.00268 |doi-access=free |issn=2234-943X |pmc=6062593 |pmid=30079312}}</ref> They have been used to study and model obesity, heart disease, diabetes, arthritis, substance abuse, anxiety, aging, temperature, pain reception, and Parkinson disease.<ref>{{cite web|title=Knockout Mice|publisher=Nation Human Genome Research Institute|year=2009|url=http://www.genome.gov/12514551}}</ref><ref name=":1">{{Cite web|title=How peppers and peppermint identified sensory receptors for temperature and pain|url=https://www.ibiology.org/neuroscience/sensory-receptors/|last=Julius|first=David|website=iBiology|language=en-US|access-date=2020-05-14}}</ref> Genetically modified mice further be divided into constitutive mouse model, in which the target gene is permanently activated or inactivated in all the cells of the animal, or conditional mouse model, in which the knockout or the overexpressed gene can be regulated in a spatiotemporal manner, which enables targeting of a specific type or subset of cells in the animal from a specific time in the life of the animal.<ref name=":2" />

Transgenic mice generated to carry cloned [[oncogene]]s and knockout mice lacking [[Tumor suppressor gene|tumor suppressing genes]] have provided good models for human [[cancer]]. Hundreds of these [[oncomouse|oncomice]] have been developed covering a wide range of cancers affecting most organs of the body and they are being refined to become more representative of human cancer.<ref name="Hanahan" /> The disease symptoms and potential drugs or treatments can be tested against these mouse models.

A mouse has been genetically engineered to have increased muscle growth and strength by overexpressing the [[insulin-like growth factor I]] (IGF-I) in differentiated [[muscle fibers]].<ref>{{cite journal|issue=6628|volume=387|pages=83–90|year=1997|doi=10.1038/387083a0|pmid=9139826|journal=Nature|title=Regulation of skeletal muscle mass in mice by a new TGF-beta superfamily member|author1=McPherron, A.|author2=Lawler, A.|author3=Lee, S.|bibcode=1997Natur.387...83M|s2cid=4271945}}</ref><ref>{{cite journal|doi=10.1073/pnas.95.26.15603|title=Viral mediated expression of insulin-like growth factor I blocks the aging-related loss of skeletal muscle function|author1=Elisabeth R. Barton-Davis|author2=Daria I. Shoturma|author3=Antonio Musaro|author4=Nadia Rosenthal|author5=H. Lee Sweeney|journal=PNAS|year=1998|volume=95|issue=26|pages=15603–15607|pmid=9861016|pmc=28090|bibcode=1998PNAS...9515603B|doi-access=free}}</ref> Another mouse has had a gene altered that is involved in [[glucose metabolism]] and runs faster, lives longer, is more sexually active and eats more without getting fatter than the average mouse (see [[Metabolic supermice]]).<ref>{{cite news|url=http://www.news.com.au/supermouse-stuns-scientists/story-e6frfkp9-1111114792115#ixzz0xFlY82PZ|agency=[[Australian Associated Press|AAP]]|title=Genetically engineered super mouse stuns scientists|date=November 3, 2007}}</ref><ref>{{cite journal|vauthors=Hakimi P, Yang J, Casadesus G, Massillon D, Tolentino-Silva F, Nye C, Cabrera M, Hagen D, Utter C, Baghdy Y, Johnson DH, Wilson DL, Kirwan JP, Kalhan SC, Hanson RW|title=Overexpression of the cytosolic form of phosphoenolpyruvate carboxykinase (GTP) in skeletal muscle repatterns energy metabolism in the mouse|journal=[[Journal of Biological Chemistry]]|volume=282|pmid=17716967|doi=10.1074/jbc.M706127200|year=2007|pages=32844–32855|issue=45|pmc=4484620|doi-access=free}}</ref> Another mouse had the [[TRPM8|TRPM8 receptor]] blocked or removed in a study involving [[capsaicin]] and [[menthol]].<ref name=":1" /> With the TRPM8 receptor removed, the mouse was unable to detect small changes in temperature and the pain associated with it.<ref name=":1" />

Great care should be taken when deciding how to use genetically modified mice in research.<ref>{{cite journal |doi=10.1111/j.1601-183X.2008.00438.x|title=Standards for the publication of mouse mutant studies|year=2009|author=Crusio, W.E.|author-link=Wim Crusio|author2=Goldowitz, D.|author3=Holmes, A.|author4=Wolfer, D.|journal=[[Genes, Brain and Behavior]]|volume=8|pages=1–4|pmid=18778401|issue=1|s2cid=205853147|doi-access=free}}</ref> Even basic issues like choosing the correct "wild-type" control mouse to use for comparison are sometimes overlooked.<ref>{{cite journal|doi=10.1021/tx200143x |title=Mispairing C57BL/6 Substrains of Genetically Engineered Mice and Wild-Type Controls Can Lead to Confounding Results as It Did in Studies of JNK2 in Acetaminophen and Concanavalin A Liver Injury|author1=Mohammed Bourdi|author2=John S. Davies|author3=Lance R. Pohl|journal=[[Chemical Research in Toxicology]]|year=2011|volume=24|issue=6|pages=794–796|pmid=21557537|pmc=3157912}}</ref>

==See also==
* [[Humanized mouse]]

==References==
{{Reflist}}

==External links==
*[http://www.informatics.jax.org/ Mouse Genome Informatics (informatics.jax.org)]
*[https://web.archive.org/web/20071024135546/http://www.mgu.har.mrc.ac.uk/ Mammalian Genetics Unit Harwell: Mouse models for human disease]
{{genetic engineering}}

[[Category:Mouse genetics]]
[[Category:1974 in biotechnology]]
[[Category:Genetic engineering]]

Genetically modified mouse - Revision history

imported>OAbot: Open access bot: url-access updated in citation with #oabot.