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Waters MD, Warren S, Hughes C, Lewis P, Zhang F. Human genetic risk of treatment with antiviral nucleoside analog drugs that induce lethal mutagenesis: The special case of molnupiravir. ENVIRONMENTAL AND MOLECULAR MUTAGENESIS 2022; 63:37-63. [PMID: 35023215 DOI: 10.1002/em.22471] [Citation(s) in RCA: 31] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/30/2021] [Revised: 12/28/2021] [Accepted: 01/08/2022] [Indexed: 06/14/2023]
Abstract
This review considers antiviral nucleoside analog drugs, including ribavirin, favipiravir, and molnupiravir, which induce genome error catastrophe in SARS-CoV or SARS-CoV-2 via lethal mutagenesis as a mode of action. In vitro data indicate that molnupiravir may be 100 times more potent as an antiviral agent than ribavirin or favipiravir. Molnupiravir has recently demonstrated efficacy in a phase 3 clinical trial. Because of its anticipated global use, its relative potency, and the reported in vitro "host" cell mutagenicity of its active principle, β-d-N4-hydroxycytidine, we have reviewed the development of molnupiravir and its genotoxicity safety evaluation, as well as the genotoxicity profiles of three congeners, that is, ribavirin, favipiravir, and 5-(2-chloroethyl)-2'-deoxyuridine. We consider the potential genetic risks of molnupiravir on the basis of all available information and focus on the need for additional human genotoxicity data and follow-up in patients treated with molnupiravir and similar drugs. Such human data are especially relevant for antiviral NAs that have the potential of permanently modifying the genomes of treated patients and/or causing human teratogenicity or embryotoxicity. We conclude that the results of preclinical genotoxicity studies and phase 1 human clinical safety, tolerability, and pharmacokinetics are critical components of drug safety assessments and sentinels of unanticipated adverse health effects. We provide our rationale for performing more thorough genotoxicity testing prior to and within phase 1 clinical trials, including human PIG-A and error corrected next generation sequencing (duplex sequencing) studies in DNA and mitochondrial DNA of patients treated with antiviral NAs that induce genome error catastrophe via lethal mutagenesis.
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Affiliation(s)
- Michael D Waters
- Michael Waters Consulting USA, Hillsborough, North Carolina, USA
| | | | - Claude Hughes
- Duke University Medical Center, Durham, North Carolina, USA
| | | | - Fengyu Zhang
- Global Clinical and Translational Research Institute, Bethesda, Maryland, USA
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2
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Sensitized mutagenesis screen in Factor V Leiden mice identifies thrombosis suppressor loci. Proc Natl Acad Sci U S A 2017; 114:9659-9664. [PMID: 28827327 DOI: 10.1073/pnas.1705762114] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Factor V Leiden (F5L ) is a common genetic risk factor for venous thromboembolism in humans. We conducted a sensitized N-ethyl-N-nitrosourea (ENU) mutagenesis screen for dominant thrombosuppressor genes based on perinatal lethal thrombosis in mice homozygous for F5L (F5L/L ) and haploinsufficient for tissue factor pathway inhibitor (Tfpi+/- ). F8 deficiency enhanced the survival of F5L/LTfpi+/- mice, demonstrating that F5L/LTfpi+/- lethality is genetically suppressible. ENU-mutagenized F5L/L males and F5L/+Tfpi+/- females were crossed to generate 6,729 progeny, with 98 F5L/LTfpi+/- offspring surviving until weaning. Sixteen lines, referred to as "modifier of Factor 5 Leiden (MF5L1-16)," exhibited transmission of a putative thrombosuppressor to subsequent generations. Linkage analysis in MF5L6 identified a chromosome 3 locus containing the tissue factor gene (F3). Although no ENU-induced F3 mutation was identified, haploinsufficiency for F3 (F3+/- ) suppressed F5L/LTfpi+/- lethality. Whole-exome sequencing in MF5L12 identified an Actr2 gene point mutation (p.R258G) as the sole candidate. Inheritance of this variant is associated with suppression of F5L/LTfpi+/- lethality (P = 1.7 × 10-6), suggesting that Actr2p.R258G is thrombosuppressive. CRISPR/Cas9 experiments to generate an independent Actr2 knockin/knockout demonstrated that Actr2 haploinsufficiency is lethal, supporting a hypomorphic or gain-of-function mechanism of action for Actr2p.R258G Our findings identify F8 and the Tfpi/F3 axis as key regulators in determining thrombosis balance in the setting of F5L and also suggest a role for Actr2 in this process.
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Masumura K, Toyoda-Hokaiwado N, Ukai A, Gondo Y, Honma M, Nohmi T. Dose-dependent de novo germline mutations detected by whole-exome sequencing in progeny of ENU-treated male gpt delta mice. MUTATION RESEARCH-GENETIC TOXICOLOGY AND ENVIRONMENTAL MUTAGENESIS 2016; 810:30-39. [DOI: 10.1016/j.mrgentox.2016.09.009] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/09/2016] [Revised: 09/20/2016] [Accepted: 09/27/2016] [Indexed: 01/06/2023]
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Jonas BA, Johnson C, Gratzinger D, Majeti R. Alkylator-Induced and Patient-Derived Xenograft Mouse Models of Therapy-Related Myeloid Neoplasms Model Clinical Disease and Suggest the Presence of Multiple Cell Subpopulations with Leukemia Stem Cell Activity. PLoS One 2016; 11:e0159189. [PMID: 27428079 PMCID: PMC4948781 DOI: 10.1371/journal.pone.0159189] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2015] [Accepted: 06/03/2016] [Indexed: 11/19/2022] Open
Abstract
Acute myeloid leukemia (AML) is a heterogeneous group of aggressive bone marrow cancers arising from transformed hematopoietic stem and progenitor cells (HSPC). Therapy-related AML and MDS (t-AML/MDS) comprise a subset of AML cases occurring after exposure to alkylating chemotherapy and/or radiation and are associated with a very poor prognosis. Less is known about the pathogenesis and disease-initiating/leukemia stem cell (LSC) subpopulations of t-AML/MDS compared to their de novo counterparts. Here, we report the development of mouse models of t-AML/MDS. First, we modeled alkylator-induced t-AML/MDS by exposing wild type adult mice to N-ethyl-N-nitrosurea (ENU), resulting in several models of AML and MDS that have clinical and pathologic characteristics consistent with human t-AML/MDS including cytopenia, myelodysplasia, and shortened overall survival. These models were limited by their inability to transplant clinically aggressive disease. Second, we established three patient-derived xenograft models of human t-AML. These models led to rapidly fatal disease in recipient immunodeficient xenografted mice. LSC activity was identified in multiple HSPC subpopulations suggesting there is no canonical LSC immunophenotype in human t-AML. Overall, we report several new t-AML/MDS mouse models that could potentially be used to further define disease pathogenesis and test novel therapeutics.
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Affiliation(s)
- Brian A. Jonas
- Department of Internal Medicine, Division of Hematology and Oncology, University of California Davis Comprehensive Cancer Center, University of California Davis School of Medicine, Sacramento, CA, United States of America
| | - Carl Johnson
- Department of Medicine, Division of Hematology, Cancer Institute, and Institute for Stem Cell Biology and Regenerative Medicine, Stanford University School of Medicine, Stanford, CA, United States of America
| | - Dita Gratzinger
- Department of Pathology, Stanford University School of Medicine, Stanford, CA, United States of America
| | - Ravindra Majeti
- Department of Medicine, Division of Hematology, Cancer Institute, and Institute for Stem Cell Biology and Regenerative Medicine, Stanford University School of Medicine, Stanford, CA, United States of America
- * E-mail:
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Masumura K, Toyoda-Hokaiwado N, Ukai A, Gondo Y, Honma M, Nohmi T. Estimation of the frequency of inherited germline mutations by whole exome sequencing in ethyl nitrosourea-treated and untreated gpt delta mice. Genes Environ 2016; 38:10. [PMID: 27350829 PMCID: PMC4918133 DOI: 10.1186/s41021-016-0035-y] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2015] [Accepted: 02/11/2016] [Indexed: 11/29/2022] Open
Abstract
Background Germline mutations are heritable and may cause health disadvantages in the next generation. To investigate trans-generational mutations, we treated male gpt delta mice with N-ethyl-N-nitrosourea (ENU) (85 mg/kg intraperitoneally, weekly on two occasions). The mice were mated with untreated female mice and offspring were obtained. Whole exome sequencing analyses were performed to identify de novo mutations in the offspring. Results At 20 weeks after the treatment, the gpt mutant frequencies in the sperm of ENU-treated mice were 21-fold higher than those in the untreated control. Liver DNA was extracted from six mice, including the father, mother, and four offspring from each family of the ENU-treated or untreated mice. In total, 12 DNA samples were subjected to whole exome sequencing analyses. We identified de novo mutations in the offspring by comparing single nucleotide variations in the parents and offspring. In the ENU-treated group, we detected 148 mutation candidates in four offspring and 123 (82 %) were confirmed as true mutations by Sanger sequencing. In the control group, we detected 12 candidate mutations, of which, three (25 %) were confirmed. The frequency of inherited mutations in the offspring from the ENU-treated family was 184 × 10−8 per base, which was 17-fold higher than that in the control family (11 × 10−8 per base). The de novo mutation spectrum in the next generation exhibited characteristic ENU-induced somatic mutations, such as base substitutions at A:T bp. Conclusions These results suggest that direct sequencing analyses can be a useful tool for investigating inherited germline mutations and that the germ cells could be a good endpoint for evaluating germline mutations, which are transmitted to offspring as inherited mutations. Electronic supplementary material The online version of this article (doi:10.1186/s41021-016-0035-y) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Kenichi Masumura
- Division of Genetics and Mutagenesis, National Institute of Health Sciences, 1-18-1 Kamiyoga, Setagaya-ku, Tokyo, 158-8501 Japan
| | - Naomi Toyoda-Hokaiwado
- Division of Genetics and Mutagenesis, National Institute of Health Sciences, 1-18-1 Kamiyoga, Setagaya-ku, Tokyo, 158-8501 Japan
| | - Akiko Ukai
- Division of Genetics and Mutagenesis, National Institute of Health Sciences, 1-18-1 Kamiyoga, Setagaya-ku, Tokyo, 158-8501 Japan
| | - Yoichi Gondo
- RIKEN BioResource Center, 3-1-1 Koyadai, Tsukuba, Ibaraki, 305-0074 Japan
| | - Masamitsu Honma
- Division of Genetics and Mutagenesis, National Institute of Health Sciences, 1-18-1 Kamiyoga, Setagaya-ku, Tokyo, 158-8501 Japan
| | - Takehiko Nohmi
- Division of Genetics and Mutagenesis, National Institute of Health Sciences, 1-18-1 Kamiyoga, Setagaya-ku, Tokyo, 158-8501 Japan ; Biological Safety Research Center, National Institute of Health Sciences, 1-18-1 Kamiyoga, Setagaya-ku, Tokyo, 158-8501 Japan
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Tomberg K, Khoriaty R, Westrick RJ, Fairfield HE, Reinholdt LG, Brodsky GL, Davizon-Castillo P, Ginsburg D, Di Paola J. Spontaneous 8bp Deletion in Nbeal2 Recapitulates the Gray Platelet Syndrome in Mice. PLoS One 2016; 11:e0150852. [PMID: 26950939 PMCID: PMC4780761 DOI: 10.1371/journal.pone.0150852] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2015] [Accepted: 02/19/2016] [Indexed: 01/06/2023] Open
Abstract
During the analysis of a whole genome ENU mutagenesis screen for thrombosis modifiers, a spontaneous 8 base pair (bp) deletion causing a frameshift in exon 27 of the Nbeal2 gene was identified. Though initially considered as a plausible thrombosis modifier, this Nbeal2 mutation failed to suppress the synthetic lethal thrombosis on which the original ENU screen was based. Mutations in NBEAL2 cause Gray Platelet Syndrome (GPS), an autosomal recessive bleeding disorder characterized by macrothrombocytopenia and gray-appearing platelets due to lack of platelet alpha granules. Mice homozygous for the Nbeal2 8 bp deletion (Nbeal2gps/gps) exhibit a phenotype similar to human GPS, with significantly reduced platelet counts compared to littermate controls (p = 1.63 x 10−7). Nbeal2gps/gps mice also have markedly reduced numbers of platelet alpha granules and an increased level of emperipolesis, consistent with previously characterized mice carrying targeted Nbeal2 null alleles. These findings confirm previous reports, provide an additional mouse model for GPS, and highlight the potentially confounding effect of background spontaneous mutation events in well-characterized mouse strains.
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Affiliation(s)
- Kärt Tomberg
- Department of Human Genetics, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Rami Khoriaty
- Department of Internal Medicine, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Randal J. Westrick
- Department of Biological Sciences, Oakland University, Rochester, Michigan, United States of America
| | | | | | - Gary L. Brodsky
- Department of Pediatrics, University of Colorado Denver, Aurora, Colorado, United States of America
| | - Pavel Davizon-Castillo
- Department of Pediatrics, University of Colorado Denver, Aurora, Colorado, United States of America
| | - David Ginsburg
- Department of Human Genetics, University of Michigan, Ann Arbor, Michigan, United States of America
- Department of Internal Medicine, University of Michigan, Ann Arbor, Michigan, United States of America
- Life Sciences Institute, University of Michigan, Ann Arbor, Michigan, United States of America
- Howard Hughes Medical Institute, University of Michigan, Ann Arbor, Michigan, United States of America
- * E-mail:
| | - Jorge Di Paola
- Department of Pediatrics, University of Colorado Denver, Aurora, Colorado, United States of America
- Human Medical Genetics and Genomics Program, University of Colorado Denver, Aurora, Colorado, United States of America
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8
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Yauk CL, Lambert IB, Meek MEB, Douglas GR, Marchetti F. Development of the adverse outcome pathway "alkylation of DNA in male premeiotic germ cells leading to heritable mutations" using the OECD's users' handbook supplement. ENVIRONMENTAL AND MOLECULAR MUTAGENESIS 2015; 56:724-750. [PMID: 26010389 DOI: 10.1002/em.21954] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/20/2015] [Revised: 03/31/2015] [Accepted: 04/01/2015] [Indexed: 06/04/2023]
Abstract
The Organisation for Economic Cooperation and Development's (OECD) Adverse Outcome Pathway (AOP) programme aims to develop a knowledgebase of all known pathways of toxicity that lead to adverse effects in humans and ecosystems. A Users' Handbook was recently released to provide supplementary guidance on AOP development. This article describes one AOP-alkylation of DNA in male premeiotic germ cells leading to heritable mutations. This outcome is an important regulatory endpoint. The AOP describes the biological plausibility and empirical evidence supporting that compounds capable of alkylating DNA cause germ cell mutations and subsequent mutations in the offspring of exposed males. Alkyl adducts are subject to DNA repair; however, at high doses the repair machinery becomes saturated. Lack of repair leads to replication of alkylated DNA and ensuing mutations in male premeiotic germ cells. Mutations that do not impair spermatogenesis persist and eventually are present in mature sperm. Thus, the mutations are transmitted to the offspring. Although there are some gaps in empirical support and evidence for essentiality of the key events for certain aspects of this AOP, the overall AOP is generally accepted as dogma and applies broadly to any species that produces sperm. The AOP was developed and used in an iterative process to test and refine the Users' Handbook, and is one of the first publicly available AOPs. It is our hope that this AOP will be leveraged to develop other AOPs in this field to advance method development, computational models to predict germ cell effects, and integrated testing strategies.
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Affiliation(s)
- Carole L Yauk
- Environmental Health Science and Research Bureau, Health Canada, Ottawa, Ontario, Canada
| | - Iain B Lambert
- Department of Biology, Carleton University, Ottawa, Ontario, Canada
| | - M E Bette Meek
- R. Samuel McLaughlin Centre for Population Health Risk Assessment, University of Ottawa, Ottawa, Ontario, Canada
| | - George R Douglas
- Environmental Health Science and Research Bureau, Health Canada, Ottawa, Ontario, Canada
| | - Francesco Marchetti
- Environmental Health Science and Research Bureau, Health Canada, Ottawa, Ontario, Canada
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Yauk CL, Aardema MJ, Benthem JV, Bishop JB, Dearfield KL, DeMarini DM, Dubrova YE, Honma M, Lupski JR, Marchetti F, Meistrich ML, Pacchierotti F, Stewart J, Waters MD, Douglas GR. Approaches for identifying germ cell mutagens: Report of the 2013 IWGT workshop on germ cell assays(☆). MUTATION RESEARCH-GENETIC TOXICOLOGY AND ENVIRONMENTAL MUTAGENESIS 2015; 783:36-54. [PMID: 25953399 DOI: 10.1016/j.mrgentox.2015.01.008] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/22/2015] [Accepted: 01/23/2015] [Indexed: 01/06/2023]
Abstract
This workshop reviewed the current science to inform and recommend the best evidence-based approaches on the use of germ cell genotoxicity tests. The workshop questions and key outcomes were as follows. (1) Do genotoxicity and mutagenicity assays in somatic cells predict germ cell effects? Limited data suggest that somatic cell tests detect most germ cell mutagens, but there are strong concerns that dictate caution in drawing conclusions. (2) Should germ cell tests be done, and when? If there is evidence that a chemical or its metabolite(s) will not reach target germ cells or gonadal tissue, it is not necessary to conduct germ cell tests, notwithstanding somatic outcomes. However, it was recommended that negative somatic cell mutagens with clear evidence for gonadal exposure and evidence of toxicity in germ cells could be considered for germ cell mutagenicity testing. For somatic mutagens that are known to reach the gonadal compartments and expose germ cells, the chemical could be assumed to be a germ cell mutagen without further testing. Nevertheless, germ cell mutagenicity testing would be needed for quantitative risk assessment. (3) What new assays should be implemented and how? There is an immediate need for research on the application of whole genome sequencing in heritable mutation analysis in humans and animals, and integration of germ cell assays with somatic cell genotoxicity tests. Focus should be on environmental exposures that can cause de novo mutations, particularly newly recognized types of genomic changes. Mutational events, which may occur by exposure of germ cells during embryonic development, should also be investigated. Finally, where there are indications of germ cell toxicity in repeat dose or reproductive toxicology tests, consideration should be given to leveraging those studies to inform of possible germ cell genotoxicity.
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Affiliation(s)
- Carole L Yauk
- Environmental Health Science and Research Bureau, Health Canada, Ottawa, ON, Canada.
| | | | - Jan van Benthem
- National Institute for Public Health and the Environment, Bilthoven, The Netherlands
| | - Jack B Bishop
- National Institute of Environmental Health Sciences, NC, USA
| | | | | | | | | | - James R Lupski
- Department of Molecular and Human Genetics, and Department of Pediatrics, Baylor College of Medicine, USA
| | - Francesco Marchetti
- Environmental Health Science and Research Bureau, Health Canada, Ottawa, ON, Canada
| | | | - Francesca Pacchierotti
- ENEA, Italian National Agency for New Technologies, Energy and Sustainable Economic Development, Italy
| | | | | | - George R Douglas
- Environmental Health Science and Research Bureau, Health Canada, Ottawa, ON, Canada.
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Hagarman JA, O'Brien TP. An essential gene mutagenesis screen across the highly conserved piebald deletion region of mouse chromosome 14. Genesis 2009; 47:392-403. [PMID: 19391113 DOI: 10.1002/dvg.20510] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The piebald deletion complex is a set of overlapping chromosomal deficiencies on distal mouse chromosome 14. We surveyed the functional genetic content of the piebald deletion region in an essential gene mutagenesis screen of 952 genomes to recover seven lethal mutants. The ENU-induced mutations were mapped to define genetic intervals using the piebald deletion panel. Lethal mutations included loci required for establishment of the left-right embryonic axis and a loss-of-function allele of Phr1 resulting in respiratory distress at birth. A functional map of the piebald region integrates experimental genetic data from the deletion panel, mutagenesis screen, and the targeted disruption of specific genes. A comparison of several genomic intervals targeted in regional mutagenesis screens suggests that the piebald region is characterized by a low gene density and high essential gene density with a distinct genomic content and organization that supports complex regulatory interactions and promotes evolutionary stability.
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Affiliation(s)
- James A Hagarman
- Department of Biomedical Sciences, Cornell University, Ithaca, New York
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Cook MN, Dunning JP, Wiley RG, Chesler EJ, Johnson DK, Miller DR, Goldowitz D. Neurobehavioral mutants identified in an ENU-mutagenesis project. Mamm Genome 2007; 18:559-72. [PMID: 17629744 DOI: 10.1007/s00335-007-9035-3] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2007] [Accepted: 05/04/2007] [Indexed: 10/23/2022]
Abstract
We report on a battery of behavioral screening tests that successfully identified several neurobehavioral mutants among a large-scale ENU-mutagenized mouse population. Large numbers of ENU-mutagenized mice were screened for abnormalities in central nervous system function based on abnormal performance in a series of behavior tasks. We developed and used a high-throughput screen of behavioral tasks to detect behavioral outliers. Twelve mutant pedigrees, representing a broad range of behavioral phenotypes, have been identified. Specifically, we have identified two open-field mutants (one displaying hyperlocomotion, the other hypolocomotion), four tail-suspension mutants (all displaying increased immobility), one nociception mutant (displaying abnormal responsiveness to thermal pain), two prepulse inhibition mutants (displaying poor inhibition of the startle response), one anxiety-related mutant (displaying decreased anxiety in the light/dark test), and one learning-and-memory mutant (displaying reduced response to the conditioned stimulus). These findings highlight the utility of a set of behavioral tasks used in a high-throughput screen to identify neurobehavioral mutants. Further analysis (i.e., behavioral and genetic mapping studies) of mutants is in progress with the ultimate goal of identification of novel genes and mouse models relevant to human disorders as well as the identification of novel therapeutic targets.
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Affiliation(s)
- Melloni N Cook
- Department of Psychology, University of Memphis, Memphis, Tennessee 38152, and VA Tennessee Valley Healthcare System, Nashville 37212, USA.
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12
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Oliver PL, Bitoun E, Davies KE. Comparative genetic analysis: the utility of mouse genetic systems for studying human monogenic disease. Mamm Genome 2007; 18:412-24. [PMID: 17514509 PMCID: PMC1998876 DOI: 10.1007/s00335-007-9014-8] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2007] [Revised: 03/19/2007] [Accepted: 03/22/2007] [Indexed: 12/23/2022]
Abstract
One of the long-term goals of mutagenesis programs in the mouse has been to generate mutant lines to facilitate the functional study of every mammalian gene. With a combination of complementary genetic approaches and advances in technology, this aim is slowly becoming a reality. One of the most important features of this strategy is the ability to identify and compare a number of mutations in the same gene, an allelic series. With the advent of gene-driven screening of mutant archives, the search for a specific series of interest is now a practical option. This review focuses on the analysis of multiple mutations from chemical mutagenesis projects in a wide variety of genes and the valuable functional information that has been obtained from these studies. Although gene knockouts and transgenics will continue to be an important resource to ascertain gene function, with a significant proportion of human diseases caused by point mutations, identifying an allelic series is becoming an equally efficient route to generating clinically relevant and functionally important mouse models.
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Affiliation(s)
- Peter L. Oliver
- Department of Physiology, Anatomy and Genetics, MRC Functional Genetics Unit, University of Oxford, South Parks Road, Oxford, OX1 3QX UK
| | - Emmanuelle Bitoun
- Department of Physiology, Anatomy and Genetics, MRC Functional Genetics Unit, University of Oxford, South Parks Road, Oxford, OX1 3QX UK
| | - Kay E. Davies
- Department of Physiology, Anatomy and Genetics, MRC Functional Genetics Unit, University of Oxford, South Parks Road, Oxford, OX1 3QX UK
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Abstract
Spermatocytes normally sustain many meiotically induced double-strand DNA breaks (DSBs) early in meiotic prophase; in autosomal chromatin, these are repaired by initiation of meiotic homologous-recombination processes. Little is known about how spermatocytes respond to environmentally induced DNA damage after recombination-related DSBs have been repaired. The experiments described here tested the hypothesis that, even though actively completing meiotic recombination, pachytene spermatocytes cultured in the absence of testicular somatic cells initiate appropriate chromatin remodeling and cell-cycle responses to environmentally induced DNA damage. Two DNA-damaging agents were employed for in vitro treatment of pachytene spermatocytes: gamma-irradiation and etoposide, a topoisomerase II (TOP2) inhibitor that results in persistent unligated DSBs. Chromatin modifications associated with DSBs were monitored after exposure by labeling surface-spread chromatin with antibodies against RAD51 (which recognizes DSBs) and the phosphorylated variant of histone H2AFX (herein designated by its commonly used symbol, H2AX), gammaH2AX (which modifies chromatin associated with DSBs). Both gammaH2AX and RAD51 were rapidly recruited to irradiation- or etoposide-damaged chromatin. These chromatin modifications imply that spermatocytes recruit active DNA damage responses, even after recombination is substantially completed. Furthermore, irradiation-induced DNA damage inhibited okadaic acid-induced progression of spermatocytes from meiotic prophase to metaphase I (MI), implying efficacy of DNA damage checkpoint mechanisms. Apoptotic responses of spermatocytes with DNA damage differed, with an increase in frequency of early apoptotic spermatocytes after etoposide treatment, but not following irradiation. Taken together, these results demonstrate modification of pachytene spermatocyte chromatin and inhibition of meiotic progress after DNA damage by mechanisms that may ensure gametic genetic integrity.
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Affiliation(s)
- Shannon Matulis
- Department of Biochemistry and Cellular and Molecular Biology, University of Tennessee, Knoxville, USA
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Hoekstra HE. Genetics, development and evolution of adaptive pigmentation in vertebrates. Heredity (Edinb) 2006; 97:222-34. [PMID: 16823403 DOI: 10.1038/sj.hdy.6800861] [Citation(s) in RCA: 396] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
The study of pigmentation has played an important role in the intersection of evolution, genetics, and developmental biology. Pigmentation's utility as a visible phenotypic marker has resulted in over 100 years of intense study of coat color mutations in laboratory mice, thereby creating an impressive list of candidate genes and an understanding of the developmental mechanisms responsible for the phenotypic effects. Variation in color and pigment patterning has also served as the focus of many classic studies of naturally occurring phenotypic variation in a wide variety of vertebrates, providing some of the most compelling cases for parallel and convergent evolution. Thus, the pigmentation model system holds much promise for understanding the nature of adaptation by linking genetic changes to variation in fitness-related traits. Here, I first discuss the historical role of pigmentation in genetics, development and evolutionary biology. I then discuss recent empirically based studies in vertebrates, which rely on these historical foundations to make connections between genotype and phenotype for ecologically important pigmentation traits. These studies provide insight into the evolutionary process by uncovering the genetic basis of adaptive traits and addressing such long-standing questions in evolutionary biology as (1) are adaptive changes predominantly caused by mutations in regulatory regions or coding regions? (2) is adaptation driven by the fixation of dominant mutations? and (3) to what extent are parallel phenotypic changes caused by similar genetic changes? It is clear that coloration has much to teach us about the molecular basis of organismal diversity, adaptation and the evolutionary process.
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Affiliation(s)
- H E Hoekstra
- Division of Biological Sciences, University of California, San Diego, La Jolla, CA 92093-0116, USA.
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15
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Smyth IM, Wilming L, Lee AW, Taylor MS, Gautier P, Barlow K, Wallis J, Martin S, Glithero R, Phillimore B, Pelan S, Andrew R, Holt K, Taylor R, McLaren S, Burton J, Bailey J, Sims S, Squares J, Plumb B, Joy A, Gibson R, Gilbert J, Hart E, Laird G, Loveland J, Mudge J, Steward C, Swarbreck D, Harrow J, North P, Leaves N, Greystrong J, Coppola M, Manjunath S, Campbell M, Smith M, Strachan G, Tofts C, Boal E, Cobley V, Hunter G, Kimberley C, Thomas D, Cave-Berry L, Weston P, Botcherby MRM, White S, Edgar R, Cross SH, Irvani M, Hummerich H, Simpson EH, Johnson D, Hunsicker PR, Little PFR, Hubbard T, Campbell RD, Rogers J, Jackson IJ. Genomic anatomy of the Tyrp1 (brown) deletion complex. Proc Natl Acad Sci U S A 2006; 103:3704-9. [PMID: 16505357 PMCID: PMC1450144 DOI: 10.1073/pnas.0600199103] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Chromosome deletions in the mouse have proven invaluable in the dissection of gene function. The brown deletion complex comprises >28 independent genome rearrangements, which have been used to identify several functional loci on chromosome 4 required for normal embryonic and postnatal development. We have constructed a 172-bacterial artificial chromosome contig that spans this 22-megabase (Mb) interval and have produced a contiguous, finished, and manually annotated sequence from these clones. The deletion complex is strikingly gene-poor, containing only 52 protein-coding genes (of which only 39 are supported by human homologues) and has several further notable genomic features, including several segments of >1 Mb, apparently devoid of a coding sequence. We have used sequence polymorphisms to finely map the deletion breakpoints and identify strong candidate genes for the known phenotypes that map to this region, including three lethal loci (l4Rn1, l4Rn2, and l4Rn3) and the fitness mutant brown-associated fitness (baf). We have also characterized misexpression of the basonuclin homologue, Bnc2, associated with the inversion-mediated coat color mutant white-based brown (B(w)). This study provides a molecular insight into the basis of several characterized mouse mutants, which will allow further dissection of this region by targeted or chemical mutagenesis.
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Affiliation(s)
- Ian M. Smyth
- *Medical Research Council Human Genetics Unit, Edinburgh EH4 2XU, United Kingdom
| | | | - Angela W. Lee
- *Medical Research Council Human Genetics Unit, Edinburgh EH4 2XU, United Kingdom
| | - Martin S. Taylor
- *Medical Research Council Human Genetics Unit, Edinburgh EH4 2XU, United Kingdom
| | - Phillipe Gautier
- *Medical Research Council Human Genetics Unit, Edinburgh EH4 2XU, United Kingdom
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | - Bob Plumb
- Wellcome Trust Sanger Institute, and
| | - Ann Joy
- Wellcome Trust Sanger Institute, and
| | | | | | | | | | | | | | | | | | | | - Philip North
- Medical Research Council Rosalind Franklin Centre for Genome Research, Hinxton CB10 1SA, United Kingdom
| | - Nicholas Leaves
- Medical Research Council Rosalind Franklin Centre for Genome Research, Hinxton CB10 1SA, United Kingdom
| | - John Greystrong
- Medical Research Council Rosalind Franklin Centre for Genome Research, Hinxton CB10 1SA, United Kingdom
| | - Maria Coppola
- Medical Research Council Rosalind Franklin Centre for Genome Research, Hinxton CB10 1SA, United Kingdom
| | - Shilpa Manjunath
- Medical Research Council Rosalind Franklin Centre for Genome Research, Hinxton CB10 1SA, United Kingdom
| | - Mark Campbell
- Medical Research Council Rosalind Franklin Centre for Genome Research, Hinxton CB10 1SA, United Kingdom
| | - Mark Smith
- Medical Research Council Rosalind Franklin Centre for Genome Research, Hinxton CB10 1SA, United Kingdom
| | - Gregory Strachan
- Medical Research Council Rosalind Franklin Centre for Genome Research, Hinxton CB10 1SA, United Kingdom
| | - Calli Tofts
- Medical Research Council Rosalind Franklin Centre for Genome Research, Hinxton CB10 1SA, United Kingdom
| | - Esther Boal
- Medical Research Council Rosalind Franklin Centre for Genome Research, Hinxton CB10 1SA, United Kingdom
| | - Victoria Cobley
- Medical Research Council Rosalind Franklin Centre for Genome Research, Hinxton CB10 1SA, United Kingdom
| | - Giselle Hunter
- Medical Research Council Rosalind Franklin Centre for Genome Research, Hinxton CB10 1SA, United Kingdom
| | - Christopher Kimberley
- Medical Research Council Rosalind Franklin Centre for Genome Research, Hinxton CB10 1SA, United Kingdom
| | - Daniel Thomas
- Medical Research Council Rosalind Franklin Centre for Genome Research, Hinxton CB10 1SA, United Kingdom
| | - Lee Cave-Berry
- Medical Research Council Rosalind Franklin Centre for Genome Research, Hinxton CB10 1SA, United Kingdom
| | - Paul Weston
- Medical Research Council Rosalind Franklin Centre for Genome Research, Hinxton CB10 1SA, United Kingdom
| | - Marc R. M. Botcherby
- Medical Research Council Rosalind Franklin Centre for Genome Research, Hinxton CB10 1SA, United Kingdom
| | - Sharon White
- *Medical Research Council Human Genetics Unit, Edinburgh EH4 2XU, United Kingdom
| | - Ruth Edgar
- *Medical Research Council Human Genetics Unit, Edinburgh EH4 2XU, United Kingdom
| | - Sally H. Cross
- *Medical Research Council Human Genetics Unit, Edinburgh EH4 2XU, United Kingdom
| | - Marjan Irvani
- Department of Biochemistry, Imperial College, London SW7 2AZ, United Kingdom
| | - Holger Hummerich
- Department of Biochemistry, Imperial College, London SW7 2AZ, United Kingdom
| | - Eleanor H. Simpson
- *Medical Research Council Human Genetics Unit, Edinburgh EH4 2XU, United Kingdom
| | - Dabney Johnson
- Life Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831; and
| | | | - Peter F. R. Little
- Department of Biochemistry, Imperial College, London SW7 2AZ, United Kingdom
| | | | - R. Duncan Campbell
- Medical Research Council Rosalind Franklin Centre for Genome Research, Hinxton CB10 1SA, United Kingdom
| | | | - Ian J. Jackson
- *Medical Research Council Human Genetics Unit, Edinburgh EH4 2XU, United Kingdom
- To whom correspondence should be addressed. E-mail:
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16
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Hentges KE, Nakamura H, Furuta Y, Yu Y, Thompson DM, O'Brien W, Bradley A, Justice MJ. Novel lethal mouse mutants produced in balancer chromosome screens. Gene Expr Patterns 2006; 6:653-65. [PMID: 16466971 DOI: 10.1016/j.modgep.2005.11.015] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2005] [Accepted: 11/19/2005] [Indexed: 10/25/2022]
Abstract
Mutagenesis screens are a valuable method to identify genes that are required for normal development. Previous mouse mutagenesis screens for lethal mutations were targeted at specific time points or for developmental processes. Here we present the results of lethal mutant isolation from two mutagenesis screens that use balancer chromosomes. One screen was localized to mouse chromosome 4, between the STS markers D4Mit281 and D4Mit51. The second screen covered the region between Trp53 and Wnt3 on mouse chromosome 11. These screens identified all lethal mutations in the balancer regions, without bias towards any phenotype or stage of death. We have isolated 19 lethal lines on mouse chromosome 4, and 59 lethal lines on chromosome 11, many of which are distinct from previous mutants that map to these regions of the genome. We have characterized the mutant lines to determine the time of death, and performed a pair-wise complementation cross to determine if the mutations are allelic. Our data suggest that the majority of mouse lethal mutations die during mid-gestation, after uterine implantation, with a variety of defects in gastrulation, heart, neural tube, vascular, or placental development. This initial group of mutants provides a functional annotation of mouse chromosomes 4 and 11, and indicates that many novel developmental phenotypes can be quickly isolated in defined genomic intervals through balancer chromosome mutagenesis screens.
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Affiliation(s)
- Kathryn E Hentges
- Department of Molecular and Human Genetics, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA.
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17
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Abstract
Humans are mammals, not bacteria or plants, yeast or nematodes, insects or fish. Mice are also mammals, but unlike gorilla and goat, fox and ferret, giraffe and jackal, they are suited perfectly to the laboratory environment and genetic experimentation. In this review, we will summarize the tools, tricks and techniques for executing forward genetic screens in the mouse and argue that this approach is now accessible to most biologists, rather than being the sole domain of large national facilities and specialized genetics laboratories.
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Affiliation(s)
- Benjamin T Kile
- Division of Cancer and Hematology, The Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville 3050, Victoria, Australia.
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18
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Affiliation(s)
- Monica J Justice
- Department of Molecular and Human Genetics, Baylor College of Medicine, One Baylor Plaza S413, Houston, TX 77030, USA.
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19
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Frank AC, Meyers KA, Welsh IC, O'Brien TP. Development of an enhanced GFP-based dual-color reporter to facilitate genetic screens for the recovery of mutations in mice. Proc Natl Acad Sci U S A 2003; 100:14103-8. [PMID: 14615591 PMCID: PMC283553 DOI: 10.1073/pnas.1936166100] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Mutagenesis screens to isolate a variety of alleles leading to null and non-null phenotypes represent an important approach for the characterization of gene function. Genetic schemes that use visible markers permit the efficient recovery of chemically induced mutations. We have developed a universal reporter system to visibly mark chromosomes for genetic screens in the mouse. The dual-color reporter is based on a single vector that drives the ubiquitous coexpression of the enhanced GFP (EGFP) spectral variants yellow and cyan. We show that widespread expression of the dual-color reporter is readily detected in embryonic stem cells, mice, and throughout developmental stages. CRE-loxP- and FLPe-FRT-mediated deletion of each color cassette demonstrates the modular design of the marker system. Random integration followed by plasmid rescue and sequence-based mapping was used to introduce the marker to a defined genomic location. Thus, single-step placement will simplify the construction of a genomewide bank of marked chromosomes. The dual-color nature of the marker permits complete identification of genetic classes of progeny as embryos or mice in classic regionally directed screens. The design also allows for more efficient and novel schemes, such as marked suppressor screens, in the mouse. The result is a versatile reporter that can be used independently or in combination with the growing sets of deletion and inversion resources to enhance the design and application of a wide variety of genetic schemes for the functional dissection of the mammalian genome.
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20
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Rivers DM, Sprague GF. Autocrine activation of the pheromone response pathway in matalpha2- cells is attenuated by SST2- and ASG7-dependent mechanisms. Mol Genet Genomics 2003; 270:225-33. [PMID: 13680367 DOI: 10.1007/s00438-003-0914-3] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2003] [Accepted: 08/01/2003] [Indexed: 11/26/2022]
Abstract
Yeast mat alpha2 mutants express both mating pheromones and both mating pheromone receptors. They show modest signaling in the pheromone response pathway, as revealed by increased levels of FUS1 transcript, yet are resistant to pheromone treatment. Together, these phenotypes suggest that alpha2- cells undergo autocrine activation of the pheromone response pathway, which is subsequently attenuated. We constructed a regulatable version of the alpha2 gene (GALalpha2) and showed that, upon loss of alpha2 activity, cells exhibit an initial robust response to pheromone that is attenuated within 3 h. We reasoned that the viability of alpha2- cells might be due to attenuation, and therefore performed a genome-wide synthetic lethal screen to identify potential adaptation components. We identified two genes, SST2 and ASG7. Loss of either of these attenuation components results in activation of the pheromone pathway in alpha2- cells. Loss of both proteins causes a more severe phenotype. Sst2 functions as a GTPase activating protein (GAP) for the Galpha subunit of the trimeric G protein. Asg7 is an a -cell specific protein that acts in concert with the alpha-cell specific a -factor receptor, Ste3, to inhibit signaling by Gbetagamma. Hence, our results suggest that mat alpha2 mutants mimic the intracellular signaling events that occur in newly fused zygotes.
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Affiliation(s)
- D M Rivers
- Institute of Molecular Biology, University of Oregon, Eugene, OR 97303-1229, USA
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21
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Svenson KL, Bogue MA, Peters LL. Invited review: Identifying new mouse models of cardiovascular disease: a review of high-throughput screens of mutagenized and inbred strains. J Appl Physiol (1985) 2003; 94:1650-9; discussion 1673. [PMID: 12626479 DOI: 10.1152/japplphysiol.01029.2003] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The mouse is a proven model for studying human disease. Many strains exist that exhibit either natural or engineered genetic variation and thereby enable the elucidation of pathways involved in the development of cardiovascular disease. Although those mouse models have been fundamental to advancing our knowledge base, we are still at an early stage in understanding how genes contribute to complex disorders. There remains a need for new animal models that closely represent human disease. To expedite their development, we have established the Center for New Mouse Models of Heart, Lung, Blood, and Sleep Disorders at The Jackson Laboratory. We are using a phenotype-driven approach to identify mutations leading to atherosclerosis, hypertension, obesity, blood disorders, lung dysfunction, thrombosis, and disordered sleep. Our high-throughput, comprehensive phenotyping draws from two sources for new models: 1) the natural variation among over 40 inbred mouse strains and 2) chemically induced, whole-genome mutagenized mice. Here, we review our cardiovascular screens and present some hypertensive, obese, and cardiovascular models identified with this approach.
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22
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Paigen K. One hundred years of mouse genetics: an intellectual history. II. The molecular revolution (1981-2002). Genetics 2003; 163:1227-35. [PMID: 12702670 PMCID: PMC1462511 DOI: 10.1093/genetics/163.4.1227] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Affiliation(s)
- Kenneth Paigen
- The Jackson Laboratory, Bar Harbor, Maine 04609-1517, USA
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23
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Abstract
Endocytic adaptor proteins select specific cargo for internalization by endocytosis through clathrin-coated pits or vesicles. Recent studies indicate that epsins might also be classified as adaptors.
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24
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Affiliation(s)
- James F Crow
- Genetics Department, University of Wisconsin, Madison, Wisconsin 53706, USA
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25
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Peterson KA, King BL, Hagge-Greenberg A, Roix JJ, Bult CJ, O'Brien TP. Functional and comparative genomic analysis of the piebald deletion region of mouse chromosome 14. Genomics 2002; 80:172-84. [PMID: 12160731 DOI: 10.1006/geno.2002.6818] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Several developmentally important genomic regions map within the piebald deletion complex on distal mouse chromosome 14. We have combined computational gene prediction and comparative sequence analysis to characterize an approximately 4.3-Mb segment of the piebald region to identify candidate genes for the phenotypes presented by homozygous deletion mice. As a result we have ordered 13 deletion breakpoints, integrated the sequence with markers from a bacterial artificial chromosome (BAC) physical map, and identified 16 known or predicted genes and >1500 conserved sequence elements (CSEs) across the region. The candidate genes identified include Phr1 (formerly Pam) and Spry2, which are mouse homologs of genes required for development in Drosophila melanogaster. Gene content, order, and position are highly conserved between mouse chromosome 14 and the orthologous region of human chromosome 13. Our studies combining computational gene prediction with genetic and comparative genomic analyses provide insight regarding the functional composition and organization of this defined chromosomal region.
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26
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Roix JJ, Hagge-Greenberg A, Bissonnette DM, Rodick S, Russell LB, O'Brien TP. Molecular and functional mapping of the piebald deletion complex on mouse chromosome 14. Genetics 2001; 157:803-15. [PMID: 11156998 PMCID: PMC1461538 DOI: 10.1093/genetics/157.2.803] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The piebald deletion complex is a set of overlapping chromosomal deficiencies surrounding the endothelin receptor B locus collected during the Oak Ridge specific-locus-test mutagenesis screen. These chromosomal deletions represent an important resource for genetic studies to dissect the functional content of a genomic region, and several developmental defects have been associated with mice homozygous for distinct piebald deletion alleles. We have used molecular markers to order the breakpoints for 20 deletion alleles that span a 15.7-18-cM region of distal mouse chromosome 14. Large deletions covering as much as 11 cM have been identified that will be useful for regionally directed mutagenesis screens to reveal recessive mutations that disrupt development. Deletions identified as having breakpoints positioned within previously described critical regions have been used in complementation studies to further define the functional intervals associated with the developmental defects. This has focused our efforts to isolate genes required for newborn respiration and survival, skeletal patterning and morphogenesis, and central nervous system development.
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Affiliation(s)
- J J Roix
- The Jackson Laboratory, 600 Main St., Bar Harbor, ME 04609, USA
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27
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Simpson EH, Johnson DK, Hunsicker P, Suffolk R, Jordan SA, Jackson IJ. The mouse Cer1 (Cerberus related or homologue) gene is not required for anterior pattern formation. Dev Biol 1999; 213:202-6. [PMID: 10452857 DOI: 10.1006/dbio.1999.9372] [Citation(s) in RCA: 48] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Cer1 is the mouse homologue of the Xenopus Cerberus gene whose product is able to induce development of head structures during embryonic development. The Cer1 protein is a member of the cysteine knot superfamily and is expressed in anterior regions of the mouse gastrula. A segmental pattern of expression with nascent and newly formed somites is also seen. This suggests an additional role in development of the axial skeleton, musculature, or peripheral nervous system. Xenopus animal cap assays and mouse germ-layer explant recombination experiments indicate that the mouse protein can act as a patterning molecule for anterior development in Xenopus, including induction of Otx2 expression, and suggest it may have a similar role in mouse development. However, we present here genetic data that demonstrate that Cer1 is not necessary for anterior patterning, Otx2 expression, somite formation, or even normal mouse morphogenesis.
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Affiliation(s)
- E H Simpson
- MRC Human Genetics Unit, Western General Hospital, Crewe Road, Edinburgh, EH4 2XU, United Kingdom
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28
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Papaioannou VE. The ascendency of developmental genetics, or how the T complex educated a generation of developmental biologists. Genetics 1999; 151:421-5. [PMID: 9927439 PMCID: PMC1460494 DOI: 10.1093/genetics/151.2.421] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Affiliation(s)
- V E Papaioannou
- Department of Genetics and Development, College of Physicians and Surgeons of Columbia University, New York, New York 10032, USA
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29
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Affiliation(s)
- A P Davis
- Life Sciences Division, Oak Ridge National Laboratory, TN 37831-8080, USA.
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30
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Wines ME, Tiffany AM, Holdener BC. Physical localization of the mouse aryl hydrocarbon receptor nuclear translocator-2 (Arnt2) gene within the c112K deletion. Genomics 1998; 51:223-32. [PMID: 9722945 DOI: 10.1006/geno.1998.5347] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The albino deletions identify at least seven functional intervals essential for pre- and postnatal development in the 6- to 10-cM region surrounding the albino coat color (c = tyrosinase) locus on mouse chromosome 7. The c112K deletion identifies a putative thymus functional region not removed by the overlapping c3H deletion. Cloning the c3H proximal breakpoint provided a starting point for construction of an 840-kb BAC contig spanning the c112K and c3H (D7Ssb3Hp) proximal breakpoints. These breakpoints are separated by 320-350 kb. The aryl hydrocarbon receptor nuclear translocator-2 (Arnt2) is completely removed by the c112K deletion and spans 130-170 kb of the interval. Although Arnt2 is a candidate for the thymus defects in c112K homozygotes, the possibility that other as yet unidentified genes in the c112K deletion are responsible for the abnormalities has not been ruled out. Arnt2 is a member of the bHLH-PAS (Per, Ahr, Arnt, Sim) family of transcription factors and shares the highest similarity with Arnt. The survival of c112K homozygotes markedly contrasts the embryonic lethality observed in Arnt-deficient embryos and suggests distinct roles for these related transcription factors during embryogenesis.
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Affiliation(s)
- M E Wines
- Program in Genetics, State University of New York at Stony Brook 11794-5215, USA
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31
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Kasarskis A, Manova K, Anderson KV. A phenotype-based screen for embryonic lethal mutations in the mouse. Proc Natl Acad Sci U S A 1998; 95:7485-90. [PMID: 9636176 PMCID: PMC22659 DOI: 10.1073/pnas.95.13.7485] [Citation(s) in RCA: 146] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
The genetic pathways that control development of the early mammalian embryo have remained poorly understood, in part because the systematic mutant screens that have been so successful in the identification of genes and pathways that direct embryonic development in Drosophila, Caenorhabditis elegans, and zebrafish have not been applied to mammalian embryogenesis. Here we demonstrate that chemical mutagenesis with ethylnitrosourea can be combined with the resources of mouse genomics to identify new genes that are essential for mammalian embryogenesis. A pilot screen for abnormal morphological phenotypes of midgestation embryos identified five mutant lines; the phenotypes of four of the lines are caused by recessive traits that map to single regions of the genome. Three mutant lines display defects in neural tube closure: one is caused by an allele of the open brain (opb) locus, one defines a previously unknown locus, and one has a complex genetic basis. Two mutations produce novel early phenotypes and map to regions of the genome not previously implicated in embryonic patterning.
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Affiliation(s)
- A Kasarskis
- Molecular Biology Program, Memorial Sloan-Kettering Cancer Center, and the Sloan-Kettering Division, Graduate School of Medical Sciences, Cornell University, 1275 York Avenue, New York, NY 10021, USA
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32
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Nadeau JH, Dunn PJ. Genomic strategies for defining and dissecting developmental and physiological pathways. Curr Opin Genet Dev 1998; 8:311-5. [PMID: 9690993 DOI: 10.1016/s0959-437x(98)80087-7] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
A major challenge in genetics research is defining and dissecting the diversity of developmental and physiological pathways that lie between genes and traits. New functional genomics methods are transforming these studies by providing comprehensive and systematic approaches that complement traditional methods of formal genetics, biochemistry, and cell biology. Together, these complementary approaches will test whether reductionism can account for the complex web of interactions that lead from genetic variation to morphological, physiological, and behavioral traits in health and disease.
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Affiliation(s)
- J H Nadeau
- Genetics Department, Case Western Reserve University School of Medicine, Cleveland, Ohio 44106-4955, USA.
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33
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Affiliation(s)
- A P Davis
- Life Sciences Division, Oak Ridge National Laboratory, P.O. Box 2009, Oak Ridge, Tennessee 37831-8080, USA
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