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Kaczmarczyk L, Mende Y, Zevnik B, Jackson WS. Manipulating the Prion Protein Gene Sequence and Expression Levels with CRISPR/Cas9. PLoS One 2016; 11:e0154604. [PMID: 27128441 PMCID: PMC4851410 DOI: 10.1371/journal.pone.0154604] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2016] [Accepted: 04/16/2016] [Indexed: 01/01/2023] Open
Abstract
The mammalian prion protein (PrP, encoded by Prnp) is most infamous for its central role in prion diseases, invariably fatal neurodegenerative diseases affecting humans, food animals, and animals in the wild. However, PrP is also hypothesized to be an important receptor for toxic protein conformers in Alzheimer's disease, and is associated with other clinically relevant processes such as cancer and stroke. Thus, key insights into important clinical areas, as well as into understanding PrP functions in normal physiology, can be obtained from studying transgenic mouse models and cell culture systems. However, the Prnp locus is difficult to manipulate by homologous recombination, making modifications of the endogenous locus rarely attempted. Fortunately in recent years genome engineering technologies, like TALENs or CRISPR/Cas9 (CC9), have brought exceptional new possibilities for manipulating Prnp. Herein, we present our observations made during systematic experiments with the CC9 system targeting the endogenous mouse Prnp locus, to either modify sequences or to boost PrP expression using CC9-based synergistic activation mediators (SAMs). It is our hope that this information will aid and encourage researchers to implement gene-targeting techniques into their research program.
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Affiliation(s)
- Lech Kaczmarczyk
- German Center for Neurodegenerative Diseases (DZNE), Bonn, Germany
| | - Ylva Mende
- Cologne Excellence Cluster on Cellular Stress Responses in Aging-associated Diseases (CECAD), Medical Faculty, University of Cologne, Cologne, Germany
| | - Branko Zevnik
- Cologne Excellence Cluster on Cellular Stress Responses in Aging-associated Diseases (CECAD), Medical Faculty, University of Cologne, Cologne, Germany
| | - Walker S. Jackson
- German Center for Neurodegenerative Diseases (DZNE), Bonn, Germany
- * E-mail:
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2
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Hall B, Limaye A, Kulkarni AB. Overview: generation of gene knockout mice. ACTA ACUST UNITED AC 2009; Chapter 19:Unit 19.12 19.12.1-17. [PMID: 19731224 DOI: 10.1002/0471143030.cb1912s44] [Citation(s) in RCA: 86] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
The technique of gene targeting allows for the introduction of engineered genetic mutations into a mouse at a determined genomic locus. The process of generating mouse models with targeted mutations was developed through both the discovery of homologous recombination and the isolation of murine embryonic stem cells (ES cells). Homologous recombination is a DNA repair mechanism that is employed in gene targeting to insert a designed mutation into the homologous genetic locus. Targeted homologous recombination can be performed in murine ES cells through electroporation of a targeting construct. These ES cells are totipotent and, when injected into a mouse blastocyst, they can differentiate into all cell types of a chimeric mouse. A chimeric mouse harboring cells derived from the targeted ES cell clone can then generate a whole mouse containing the desired targeted mutation. The initial step for the generation of a mouse with a targeted mutation is the construction of an efficient targeting vector that will be introduced into the ES cells.
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Affiliation(s)
- Bradford Hall
- Department of Health and Human Services, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, Maryland, USA
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3
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Maass K, Ghanem A, Kim JS, Saathoff M, Urschel S, Kirfel G, Grümmer R, Kretz M, Lewalter T, Tiemann K, Winterhager E, Herzog V, Willecke K. Defective epidermal barrier in neonatal mice lacking the C-terminal region of connexin43. Mol Biol Cell 2004; 15:4597-608. [PMID: 15282340 PMCID: PMC519152 DOI: 10.1091/mbc.e04-04-0324] [Citation(s) in RCA: 122] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
More than 97% of mice in which the C-terminal region of connexin43 (Cx43) was removed (designated as Cx43K258stop) die shortly after birth due to a defect of the epidermal barrier. The abnormal expression of Cx43K258stop protein in the uppermost layers of the epidermis seems to perturb terminal differentiation of keratinocytes. In contrast to Cx43-deficient mice, neonatal Cx43K258stop hearts show no lethal obstruction of the right ventricular outflow tract, but signs of dilatation. Electrocardiographies of neonatal hearts reveal repolarization abnormalities in 20% of homozygous Cx43K258stop animals. The very rare adult Cx43K258stop mice show a compensation of the epidermal barrier defect but persisting impairment of cardiac function in echocardiography. Female Cx43K258stop mice are infertile due to impaired folliculogenesis. Our results indicate that the C-terminally truncated Cx43K258stop mice lack essential functions of Cx43, although the truncated Cx43 protein can form open gap junctional channels.
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Affiliation(s)
- Karen Maass
- Institut für Genetik, Universitat Bonn, D-53117 Bonn, Germany
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4
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Cases S, Zhou P, Shillingford JM, Wiseman BS, Fish JD, Angle CS, Hennighausen L, Werb Z, Farese RV. Development of the mammary gland requires DGAT1 expression in stromal and epithelial tissues. Development 2004; 131:3047-55. [PMID: 15163627 PMCID: PMC2775443 DOI: 10.1242/dev.01158] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Mammary gland development is a complex process that is dependent on interactions between the developing mammary epithelium and the surrounding stromal tissues. We show that mice lacking the triglyceride synthesis enzyme acyl CoA:diacylglycerol transferase 1 (DGAT1) have impaired mammary gland development, characterized by decreased epithelial proliferation and alveolar development, and reduced expression of markers of functional differentiation. Transplantation studies demonstrate that the impaired development results from a deficiency of DGAT1 in both the stromal and epithelial tissues. Our findings are the first to link defects in stromal lipid metabolism to impaired mammary gland development.
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Affiliation(s)
- Sylvaine Cases
- Gladstone Institute of Cardiovascular Disease, San Francisco, CA 94141-1900, USA
- Author for correspondence
| | - Ping Zhou
- Gladstone Institute of Cardiovascular Disease, San Francisco, CA 94141-1900, USA
| | - Jonathan M. Shillingford
- Laboratory of Genetics and Physiology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA
| | - Bryony S. Wiseman
- Department of Anatomy, University of California, San Francisco, CA 94143, USA
| | - Jo Dee Fish
- Gladstone Institute of Cardiovascular Disease, San Francisco, CA 94141-1900, USA
| | - Christina S. Angle
- Gladstone Institute of Cardiovascular Disease, San Francisco, CA 94141-1900, USA
| | - Lothar Hennighausen
- Laboratory of Genetics and Physiology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA
| | - Zena Werb
- Cardiovascular Research Institute, University of California, San Francisco, CA 94143, USA
- Department of Anatomy, University of California, San Francisco, CA 94143, USA
| | - Robert V. Farese
- Gladstone Institute of Cardiovascular Disease, San Francisco, CA 94141-1900, USA
- Cardiovascular Research Institute, University of California, San Francisco, CA 94143, USA
- Department of Medicine, University of California, San Francisco, CA 94143, USA
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5
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McEwan C, Melton DW. A simple genotyping assay for the Hprt null allele in mice produced from the HM-1 and E14TG2a mouse embryonic stem cell lines. Transgenic Res 2003; 12:519-20. [PMID: 12885172 DOI: 10.1023/a:1024273324890] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- Carolanne McEwan
- Sir Alastair Currie Cancer Research UK Laboratories, Molecular Medicine Centre, University of Edinburgh, Western General Hospital, Crewe Road, EH4 2XU Edinburgh, UK
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6
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Cearley JA, Detloff PJ. Efficient repetitive alteration of the mouse Huntington's disease gene by management of background in the tag and exchange gene targeting strategy. Transgenic Res 2001; 10:479-88. [PMID: 11817536 DOI: 10.1023/a:1013015616732] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The introduction of subtle mutations to predetermined locations in the mouse genome has aided in the assessment of gene function and the precise modeling of inherited disorders. Subtle mutations can be engineered into the mouse genome by the tag and exchange gene targeting strategy (Askew et al., 1993; Stacey et al., 1994; Wu et al., 1994). This two-step method involves both a positive and a negative selection. The negative selection step typically generates a large amount of undesired background that may prevent the practical recovery of gene targeted clones (Vazquez et al., 1998). In this work we describe a strategy to effectively manage this background by calculation of a tolerable level of background for a specific targeting event, pre-screening for clones with low background, subcloning and growth of cell lines under selection. This strategy was used to repeatedly and efficiently alter the mouse Huntington's disease homologue (Hdh) resulting in an average of 15 percent of the clones having the desired modification. Analysis of the remaining background clones showed they arose de novo by a mechanism that involved physical loss of the marker rather than mutation or inactivation. We calculated the rate of loss of this marker as 8.3 x 10(-6) events/cell/generation. We further show that the exchanged clones retained the capacity to contribute to the mouse germline demonstrating the utility of this strategy in the production of mouse lines with Hdh variants.
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Affiliation(s)
- J A Cearley
- Department of Biochemistry and Molecular Genetics, University of Alabama at Birmingham, 35294, USA
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7
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Divoky V, Liu Z, Ryan TM, Prchal JF, Townes TM, Prchal JT. Mouse model of congenital polycythemia: Homologous replacement of murine gene by mutant human erythropoietin receptor gene. Proc Natl Acad Sci U S A 2001; 98:986-91. [PMID: 11158582 PMCID: PMC14696 DOI: 10.1073/pnas.98.3.986] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
Mutations causing truncations of the cytoplasmic domain of the human erythropoietin receptor (EPOR) result in a dominantly inherited disorder-primary familial congenital polycythemia. This disorder is characterized by increased numbers of erythrocytes (polycythemia) and by in vitro hypersensitivity of erythroid precursors to erythropoietin. The consequences of EPOR truncation in nonerythroid tissues are unknown. We replaced the murine EPOR gene with a wild-type human EPOR gene and a mutant human EPOR gene that we initially identified in a patient with polycythemia. This mutation leads to an EPOR truncated after the first tyrosine residue of the intracellular domain. Mice heterozygous for this mutant allele and a wild-type human EPOR allele mimicked the human disorder. Interestingly, mice that were homozygous for the mutant human allele were severely polycythemic but viable. Our results provide a model for functional studies of EPOR-triggered signaling pathways in erythropoiesis. These animals can now be used to investigate the molecular pathophysiology of this gain-of-function EPOR mutation in erythroid tissue and in those nonerythroid tissues that express EPOR.
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Affiliation(s)
- V Divoky
- Department of Medicine, Division of Hematology, University of Alabama at Birmingham, AL 35294, USA
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8
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Wallace H, Ansell R, Clark J, McWhir J. Pre-selection of integration sites imparts repeatable transgene expression. Nucleic Acids Res 2000; 28:1455-64. [PMID: 10684942 PMCID: PMC111032 DOI: 10.1093/nar/28.6.1455] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Variable gene expression amongst transgenic lines occurs due to copy number and to random associations of incoming DNA with chromosomal elements at the site of integration. Here we describe a method of identifying sites permissive for transgene expression and their use for efficient introduction of single copy transgenes by homologous recombination. ES clones were selected in HAT medium for expression of a randomly integrated HPRT marker lying 5' to an Oct4/ lacZ transgene. 794 clones were assessed in vitro for appropriate down-regulation of lacZ following differentiation. Two clones were chosen for further analysis which displayed appropriate and inappropriate gene regulation (clones 710 and 91, respectively). Three developmental promoters (thyroglobulin, Hox2.6 and Myf5) were then sequentially introduced into the original insertion sites in each clone (710 and 91) by homologous recombination, to drive expression of lacZ. Transgenic embryos were assessed for their ability to direct lacZ expression to tissues in which the respective promoter sequences are normally active. The site which appropriately down-regulated lacZ in vitro (710) also showed appropriate in vivo regulation of lacZ from the three developmental promoters. Site 91, however, directed an additional pattern of ectopic expression, which was common to all four promoters. Pre-selection of genomic sites for the introduction of transgenes by gene targeting improves the repeatability of transgene expression and provides an efficient means of single copy transgene introduction by homologous recombination.
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Affiliation(s)
- H Wallace
- Department of Molecular Biology, Roslin Institute, Roslin, Midlothian EH29 5PS, UK
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9
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Dickinson P, Kimber WL, Kilanowski FM, Webb S, Stevenson BJ, Porteous DJ, Dorin JR. Enhancing the efficiency of introducing precise mutations into the mouse genome by hit and run gene targeting. Transgenic Res 2000; 9:55-66. [PMID: 10853269 DOI: 10.1023/a:1008915026660] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The creation of precise clinical mutations by targeting is important in elucidating disease pathogenesis using mouse models. 'Hit and run' gene targeting is an elegant method to achieve this goal. This uses first a positive selection to introduce the targeting vector carrying the required mutation and then a negative selection to identify clones which have removed vector and wild-type sequences by intrachromosomal recombination. However, this approach has only been successfully used in a handful of cases. We used this procedure to introduce precise clinical mutations into the exon 10 region of the cystic fibrosis transmembrane conductance regulator (Cftr) gene. Using a CMV promoter driven hygromycin/thymidine kinase (hyg/tk) fusion gene as both our dominant and negative selectable marker, we targeted the Cftr locus very efficiently but only identified false runs after the negative selection step. This defect in thymidine kinase induced toxicity to gancyclovir correlated with methylation of the transgene. Consequently we devised a stringent screening procedure to select only true 'run' clones. Unfortunately these 'run' clones had lost the mutation so we altered the vector design to bias the run step to retain the mutation and used a different tk selection cassette with a HSVtk promoter sequence. This new vector design allowed both efficient 'hit and run' for two cystic fibrosis (CF) mutations with no false positives and successful germline transmission of the novel G480C missense mutation.
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Affiliation(s)
- P Dickinson
- MRC Human Genetics Unit, Western General Hospital, Edinburgh
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10
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Gschwind M, Huber G. Introduction of hereditary disease-associated mutations into the beta-amyloid precursor protein gene of mouse embryonic stem cells: a comparison of homologous recombination methods. Mol Cell Biol 1998; 18:4651-8. [PMID: 9671475 PMCID: PMC109051 DOI: 10.1128/mcb.18.8.4651] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
Two different approaches for introducing pathogenic mutations into the beta-amyloid precursor protein gene in mouse embryonic stem cells were compared. Both approaches require two sequential modifications of the targeting locus by homologous recombinations. One approach was a "targeting-in-out" procedure that is based on a double-replacement strategy, and the other was a "hit-and-run" procedure that makes use of an unstable genomic duplication after vector integration. Both approaches showed similar targeting frequencies for the first step. In the targeting-in-out procedure, targeted-in embryonic stem cell clones with the desired mutation and an intron-located selection cassette were obtained at a high frequency after the first step. Targeting out, however, resulted not only in the expected loss of the intron-located selection cassette but also in unavoidable reversion to wild type. In contrast, pure mutants, i.e., those without additional genomic changes, were generated by the hit-and-run procedure. Although targeted-in embryonic stem cells might be used to generate animals with modified beta-amyloid precursor protein, the hit-and-run procedure appears to be the superior way to target gene modifications in vivo, leading to pure, correct mutants. For further improvements, optimization of the homologous recombination efficiency could be envisaged.
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Affiliation(s)
- M Gschwind
- Pharma Division, Preclinical CNS Research, F. Hoffmann-La Roche Ltd., CH-4070 Basel, Switzerland
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11
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Vilotte JL, L'Huillier P, Mercier JC. Modification and repression of genes expressed in the mammary gland using gene targeting and other technologies. J Mammary Gland Biol Neoplasia 1998; 3:351-62. [PMID: 10819520 DOI: 10.1023/a:1018775729834] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Transgenic experiments using oocyte micro-injection methodology are often performed in order to target expression of a foreign gene in a specific tissue or, to a lesser extent, to study the regulation of gene expression. However, the isolation of embryonic stem cells in mice and the development of antisense and ribozyme technologies have allowed more subtle alterations of endogenous gene expression to be achieved. The mammary gland is one of the few organs able to undergo several cycles of development, differentiation and apoptosis through complex multihormonal regulation during adult life. It is thus an attractive model to assess the in vivo function of some genes potentially involved in these mechanisms, either by silencing them or by partially repressing their expression. Furthermore, such alterations of gene expression have also been performed for more applied objectives such as the modification of milk composition for nutritional and technological purposes. This review will describe the experimental procedures used toward these aims and the results already obtained in this field. Some potential new targets will be suggested.
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Affiliation(s)
- J L Vilotte
- Laboratoire de Génétique Biochimique et de Cytogénétique, Jouy-en-Josas, France.
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12
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Hormuzdi SG, Penttinen R, Jaenisch R, Bornstein P. A gene-targeting approach identifies a function for the first intron in expression of the alpha1(I) collagen gene. Mol Cell Biol 1998; 18:3368-75. [PMID: 9584177 PMCID: PMC108918 DOI: 10.1128/mcb.18.6.3368] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/1998] [Accepted: 03/10/1998] [Indexed: 02/07/2023] Open
Abstract
The role of the first intron of the Col1A1 gene in the regulation of type I collagen synthesis remains uncertain and controversial despite numerous studies that have made use of transgenic and transfection experiments. To examine the importance of the first intron in regulation of the gene, we have used the double-replacement method of gene targeting to introduce, by homologous recombination in embryonic stem (ES) cells, a mutated Col1A1 allele (Col-IntDelta). The Col-IntDelta allele contains a 1. 3-kb deletion within intron I and is also marked by the introduction of a silent mutation that created an XhoI restriction site in exon 7. Targeted mice were generated from two independently derived ES cell clones. Mice carrying two copies of the mutated gene were born in the expected Mendelian ratio, developed normally, and showed no apparent abnormalities. We used heterozygous mice to determine whether expression of the mutated allele differs from that of the normal allele. For this purpose, we developed a reverse transcription-PCR assay which takes advantage of the XhoI polymorphism in exon 7. Our results indicate that in the skin, and in cultured cells derived from the skin, the intron plays little or no role in constitutive expression of collagen I. However, in the lungs of young mice, the mutated allele was expressed at about 75% of the level of the normal allele, and in the adult lung expression was decreased to less than 50%. These results were confirmed by RNase protection assays which demonstrated a two- to threefold decrease in Col1A1 mRNA in lungs of homozygous mutant mice. Surprisingly, in cultured cells derived from the lung, the mutated allele was expressed at a level similar to that of the wild-type allele. Our results also indicated an age-dependent requirement for the intact intron in expression of the Col1A1 gene in muscle. Since the intron is spliced normally, and since the mutant allele is expressed as well as the wild-type allele in the skin, reduced mRNA stability is unlikely to contribute to the reduction in transcript levels. We conclude that the first intron of the Col1A1 gene plays a tissue-specific and developmentally regulated role in transcriptional regulation of the gene. Our experiments demonstrate the utility of gene-targeting techniques that produce subtle mutations for studies of cis-acting elements in gene regulation.
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Affiliation(s)
- S G Hormuzdi
- Department of Biochemistry, University of Washington, Seattle, Washington 98195, USA
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13
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Vazquez JC, Nogues C, Rucker EB, Piedrahita JA. Factors affecting the efficiency of introducing precise genetic changes in ES cells by homologous recombination: tag-and-exchange versus the Cre-loxp system. Transgenic Res 1998; 7:181-93. [PMID: 10576864 DOI: 10.1023/a:1008888929552] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
The introduction of genetic modifications in specific genes by homologous recombination provides a powerful tool for elucidation of structure-function relationships of proteins of biological interest. Presently, there are several alternative methods of homologous recombination that permit the introduction of small genetic modifications in specific loci. Two of the most widely used methods are the tag-and-exchange, based on the use of positive-negative selection markers, and the Cre-loxP system, based on the use of a site-specific recombinase. The efficiency of detection of targeting events at different loci using the two systems was compared. Additionally, we analysed how the distance between two gene markers placed within the region of homology of a targeting vector affects the rate at which both markers are introduced into the locus during the homologous recombination event. Our results indicate that the method based on the use of positive-negative selection markers was less efficient than the Cre-loxP based system, irrespective of locus or type of positive-negative selection. It was also determined that as the distance between the selectable marker and the genetic modification being introduced increases, there is a progressive reduction in the efficiency of detecting events with the desired genetic modification.
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Affiliation(s)
- J C Vazquez
- Department of Veterinary Anatomy and Public Health, Texas A&M University, College Station 77343-4488, USA
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14
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Magin TM, Schröder R, Leitgeb S, Wanninger F, Zatloukal K, Grund C, Melton DW. Lessons from keratin 18 knockout mice: formation of novel keratin filaments, secondary loss of keratin 7 and accumulation of liver-specific keratin 8-positive aggregates. J Cell Biol 1998; 140:1441-51. [PMID: 9508776 PMCID: PMC2132680 DOI: 10.1083/jcb.140.6.1441] [Citation(s) in RCA: 175] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/1997] [Revised: 01/15/1998] [Indexed: 02/06/2023] Open
Abstract
Here, we report on the analysis of keratin 18 null mice. Unlike the ablation of K8, which together with K18 is expressed in embryonic and simple adult epithelia, K18 null mice are viable, fertile, and show a normal lifespan. In young K18 null mice, hepatocytes were completely devoid of keratin filaments. Nevertheless, typical desmosomes were formed and maintained. Old K18 null mice, however, developed a distinctive liver pathology with abnormal hepatocytes containing K8-positive aggregates. These stained positively for ubiquitin and MM120-1 and were identified as Mallory bodies, one hallmark of human alcoholic hepatitis. This is the first demonstration that the ablation of one keratin leads to the accumulation of its single partner. Another striking finding was the absence or drastic down regulation of K7 in several tissues despite its ongoing transcription. Moreover, K18 null mice revealed new insights in the filament-forming capacity of the tail-less K19 in vivo. Due to the unexpected secondary loss of K7, only K8/19 are expressed in the uterine epithelium of K18 null mice. Immunoelectron microscopy of this tissue demonstrated the presence of typical K8/19 IF, thus highlighting in vivo that K19 is a fully competent partner for K8.
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Affiliation(s)
- T M Magin
- Institut fuer Genetik, Abteilung Molekulargenetik, Universitat Bonn, Bonn, Germany.
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15
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Liu Y, Suzuki K, Reed JD, Grinberg A, Westphal H, Hoffmann A, Döring T, Sandhoff K, Proia RL. Mice with type 2 and 3 Gaucher disease point mutations generated by a single insertion mutagenesis procedure. Proc Natl Acad Sci U S A 1998; 95:2503-8. [PMID: 9482915 PMCID: PMC19391 DOI: 10.1073/pnas.95.5.2503] [Citation(s) in RCA: 88] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/1997] [Accepted: 12/24/1997] [Indexed: 02/06/2023] Open
Abstract
Gaucher disease is caused by mutations in the gene encoding the lysosomal enzyme glucocerebrosidase (GC). Three clinical types of Gaucher disease have been defined according to the presence (type 2 and 3) or absence (type 1) of central nervous system disease and severity of clinical manifestations. The clinical course of the disease correlates with the mutation carried by the GC gene. To produce mice with point mutations that correspond to the clinical types of Gaucher disease, we have devised a highly efficient one-step mutagenesis method-the single insertion mutagenesis procedure (SIMP)-to introduce human disease mutations into the mouse GC gene. By using SIMP, mice were generated carrying either the very severe RecNciI mutation that can cause type 2 disease or the less severe L444P mutation associated with type 3 disease. Mice homozygous for the RecNciI mutation had little GC enzyme activity and accumulated glucosylceramide in brain and liver. In contrast, the mice homozygous for the L444P mutation had higher levels of GC activity and no detectable accumulation of glucosylceramide in brain and liver. Surprisingly, both point mutation mice died within 48 hr of birth, apparently of a compromised epidermal permeability barrier caused by defective glucosylceramide metabolism in the epidermis.
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Affiliation(s)
- Y Liu
- Section on Biochemical Genetics, Genetics and Biochemistry Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA
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16
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Cohen-Tannoudji M, Robine S, Choulika A, Pinto D, El Marjou F, Babinet C, Louvard D, Jaisser F. I-SceI-induced gene replacement at a natural locus in embryonic stem cells. Mol Cell Biol 1998; 18:1444-8. [PMID: 9488460 PMCID: PMC108858 DOI: 10.1128/mcb.18.3.1444] [Citation(s) in RCA: 88] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Gene targeting is a very powerful tool for studying mammalian development and physiology and for creating models of human diseases. In many instances, however, it is desirable to study different modifications of a target gene, but this is limited by the generally low frequency of homologous recombination in mammalian cells. We have developed a novel gene-targeting strategy in mouse embryonic stem cells that is based on the induction of endogenous gap repair processes at a defined location within the genome by induction of a double-strand break (DSB) in the gene to be mutated. This strategy was used to knock in an NH2-ezrin mutant in the villin gene, which encodes an actin-binding protein expressed in the brush border of the intestine and the kidney. To induce the DSB, an I-SceI yeast meganuclease restriction site was first introduced by gene targeting to the villin gene, followed by transient expression of I-SceI. The repair of the ensuing DSB was achieved with high efficiency (6 x 10[-6]) by a repair shuttle vector sharing only a 2.8-kb region of homology with the villin gene and no negative selection marker. Compared to conventional gene-targeting experiments at the villin locus, this represents a 100-fold stimulation of gene-targeting frequency, notwithstanding a much lower length of homology. This strategy will be very helpful in facilitating the targeted introduction of several types of mutations within a gene of interest.
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Affiliation(s)
- M Cohen-Tannoudji
- Unité de Biologie du Développement, CNRS URA 1960, Institut Pasteur, Paris, France
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17
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Melton DW, Ketchen AM, Selfridge J. Stability of HPRT marker gene expression at different gene-targeted loci: observing and overcoming a position effect. Nucleic Acids Res 1997; 25:3937-43. [PMID: 9380520 PMCID: PMC146987 DOI: 10.1093/nar/25.19.3937] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
For sophisticated gene targeting procedures requiring two sequential selective steps to operate efficiently it is essential that the marker genes used are not prone to position effects. The double replacement gene targeting procedure, to produce mice with subtle gene alterations, is based on the use of hypoxanthine phosphoribosyltransferase ( HPRT) minigenes in HPRT-deficient embryonic stem cells. Our standard HPRTminigene, under the control of the mouse phosphoglycerate kinase-1 gene promoter, was stably expressed at five of six target loci examined. At the remaining locus, DNA ligase I (Lig1), expression of this minigene was highly unstable. A different minigene, under the control of the mouse HPRT promoter and embedded in its natural CpG-rich island, overcame this position effect and was stably expressed when targeted to the identical site in the Lig1 locus. The promoter region of the stably expressed minigene remained unmethylated, while the promoter of the unstably expressed minigene rapidly became fully methylated. The difference in the stability of HPRT minigene expression at the same target locus can be explained in the context of the different lengths of their CpG-rich promoter regions with associated transcription factors and a resulting difference in their susceptibility to DNA methylation, rather than by differences in promoter strength.
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Affiliation(s)
- D W Melton
- Institute of Cell and Molecular Biology, University of Edinburgh, Edinburgh EH9 3JR, UK.
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18
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Whyatt LM, Rathjen PD. Introduction of precise alterations into the mouse genome with high efficiency by stable tag-exchange gene targeting: implications for gene targeting in ES cells. Nucleic Acids Res 1997; 25:2381-8. [PMID: 9171089 PMCID: PMC146761 DOI: 10.1093/nar/25.12.2381] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
The efficiency of tag-and-exchange gene targeting approaches for the introduction of precise genomic modifications is compromised by high levels of non-homologous recombinants which survive selection due to loss of tag gene expression, often by physical loss of the tag gene. We describe a modified approach, termed stable tag-exchange, which incorporates an additional positive selection (stability) cassette to circumvent this limitation. HPRT (tag) and neo (stability) cassettes, separated by 4.9 kb of homologous DNA, were introduced efficiently into the LIF locus of ES cells. The tag cassette was substituted for abeta-galactosidase gene in exchange step targeting. Direct comparison of the tag-and-exchange and stable tag-exchange approaches indicated respective targeting efficiencies of 21% and 88%. The increased stable tag-exchange targeting efficiency resulted from elimination of >75% of background lines which survived tag-and-exchange selection due to physical loss of the tag gene. These resulted from reversion of the tagged allele to wild-type which is therefore a major contributor to tag-and-exchange targeting background. Our results extend the application of gene targeting by demonstrating a rationale for single-step integration of multiple regions of extended non-homology, and providing an efficient system for the repeated introduction of precise alterations into the mammalian genome.
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Affiliation(s)
- L M Whyatt
- Department of Biochemistry, The University of Adelaide, Adelaide, SA 5005, Australia
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19
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Bronson SK, Plaehn EG, Kluckman KD, Hagaman JR, Maeda N, Smithies O. Single-copy transgenic mice with chosen-site integration. Proc Natl Acad Sci U S A 1996; 93:9067-72. [PMID: 8799155 PMCID: PMC38596 DOI: 10.1073/pnas.93.17.9067] [Citation(s) in RCA: 239] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
We describe a general way of introducing transgenes into the mouse germ line for comparing different sequences without the complications of variation in copy number and insertion site. The method uses homologous recombination in embryonic stem (ES) cells to generate mice having a single copy of a transgene integrated into a chosen location in the genome. To test the method, a single copy murine bcl-2 cDNA driven by either a chicken beta-actin promoter or a human beta-actin promoter has been inserted immediately 5' to the X-linked hypoxanthine phosphoribosyltransferase locus by a directly selectable homologous recombination event. The level of expression of the targeted bcl-2 transgene in ES cells is identical in independently isolated homologous recombinants having the same promoter yet varies between the different promoters. In contrast, the expression of bcl-2 transgenes having the same (chicken beta-actin) promoter varies drastically when they are independently integrated at random insertion sites. Both promoters direct broad expression of the single-copy transgene in mice derived from the respective targeted ES cells. In vitro and in vivo, the human beta-actin promoter consistently directed a higher level of transgene expression than the chicken beta-actin promoter.
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Affiliation(s)
- S K Bronson
- Department of Pathology, University of North Carolina, Chapel Hill 27599-7525, USA
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20
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Affiliation(s)
- M Jasin
- Cell Biology and Genetics Program, Memorial Sloan-Kettering Cancer Center, New York, NY 10021, USA
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21
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Rajewsky K, Gu H, Kühn R, Betz UA, Müller W, Roes J, Schwenk F. Conditional gene targeting. J Clin Invest 1996; 98:600-3. [PMID: 8698848 PMCID: PMC507466 DOI: 10.1172/jci118828] [Citation(s) in RCA: 350] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Affiliation(s)
- K Rajewsky
- Institute for Genetics, University of Cologne, Germany
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22
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Abstract
As a result of gene targeting, selectable markers are usually permanently introduced into the mammalian genome. Multiple gene targeting events in the same cell line can therefore exhaust the pool of markers available and limit subsequent manipulations or genetic analysis. In this study, we describe the combined use of homologous and CRE-loxP-mediated recombination to generate mouse embryonic stem cell lines carrying up to four targeted mutations and devoid of exogenous selectable markers. A cassette that contains both positive and negative selectable markers flanked by loxP sites, rendering it excisable by the CRE protein, was constructed. Homologous recombination and positive selection were used to disrupt the Rep-3 locus, a gene homologous to members of the mutS family of DNA mismatch repair genes. CRE-loxP-mediated recombination and negative selection were then used to recover clones in which the cassette had been excised. The remaining allele of Rep-3 was then subjected to a second round of targeting and excision with the same construct to generate homozygous, marker-free cell lines. Subsequently, both alleles of mMsh2, another mutS homolog, were disrupted in the same fashion to obtain cell lines homozygous for targeted mutations at both the Rep-3 and mMsh2 loci and devoid of selectable markers. Thus, embryonic stem cell lines obtained in this fashion are suitable for further manipulation and analysis involving the use of selectable markers.
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Affiliation(s)
- A Abuin
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas 77030, USA
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23
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Porter RM, Leitgeb S, Melton DW, Swensson O, Eady RA, Magin TM. Gene targeting at the mouse cytokeratin 10 locus: severe skin fragility and changes of cytokeratin expression in the epidermis. J Cell Biol 1996; 132:925-36. [PMID: 8603923 PMCID: PMC2120736 DOI: 10.1083/jcb.132.5.925] [Citation(s) in RCA: 80] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
Bullous congenital ichthyosiform erythroderma (BCIE) is a dominantly inherited blistering skin disorder caused by point mutations in the suprabasal cytokeratins 1 or 10. Targeting the murine cytokeratin 10 gene in ES cells resulted in mice with different phenotypes in the homozygotes and heterozygotes; both of which exhibit similarities to specific clinical characteristics of BCIE. Homozygotes suffered from severe skin fragility and died shortly after birth. Heterozygotes were apparently unaffected at birth, but developed hyperkeratosis with age. In both genotypes, aggregation of cytokeratin intermediate filaments, changes in cytokeratin expression, and alterations in the program of epidermal differentiation were observed. In addition we demonstrate, for the first time, the existence of the murine equivalent of human cytokeratin 16.
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Affiliation(s)
- R M Porter
- Institute of Cell and Molecular Biology, University of Edinburgh
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24
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Lewis J, Yang B, Detloff P, Smithies O. Gene modification via "plug and socket" gene targeting. J Clin Invest 1996; 97:3-5. [PMID: 8550847 PMCID: PMC507055 DOI: 10.1172/jci118403] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Affiliation(s)
- J Lewis
- University of North Carolina, Chapel Hill 27599, USA
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25
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Abstract
Modification of the genetic content of cultured cells or of whole animals is now a key strategy in both basic biological research and applied biotechnology. Yet obtaining the desired level and specificity of expression of an introduced gene remains highly problematic. One solution could be to couple expression of a transgene to that of an appropriate intact genomic locus. The identification and functional characterization of RNA sequences known as internal ribosome entry sites now offer the possibility of achieving precise control of transgene expression through the generation of dicistronic fusion mRNAs.
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Affiliation(s)
- P S Mountford
- Centre for Animal Biotechnology, School of Veterinary Science, University of Melbourne, Parkville, Victoria, Australia
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26
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Stacey A, Schnieke A, Kerr M, Scott A, McKee C, Cottingham I, Binas B, Wilde C, Colman A. Lactation is disrupted by alpha-lactalbumin deficiency and can be restored by human alpha-lactalbumin gene replacement in mice. Proc Natl Acad Sci U S A 1995; 92:2835-9. [PMID: 7708733 PMCID: PMC42313 DOI: 10.1073/pnas.92.7.2835] [Citation(s) in RCA: 70] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Mice carrying either a deletion of the murine alpha-lactalbumin (alpha-lac) gene (null allele) or its replacement by the human alpha-lac gene (humanized allele) have been generated by gene targeting. Homozygous null females are alpha-lac-deficient, produce reduced amounts of thickened milk containing little or no lactose, and cannot sustain their offspring. This provides definitive evidence that alpha-lac is required for lactose synthesis and that lactose is important for milk production. Females homozygous for the humanized allele lactate normally, indicating that human alpha-lac can replace murine alpha-lac. Mouse and human alpha-lac expression was compared in mice heterozygous for the humanized allele. The human gene expressed approximately 15-fold greater mRNA and approximately 14-fold greater protein than the mouse, indicating that the major determinants of human alpha-lac expression are close to, or within, the human gene and that the mouse locus does not exert a negative influence on alpha-lac expression. Variations in alpha-lac expression levels in nondeficient mice did not affect milk lactose concentration, but the volume of milk increased slightly in mice homozygous for the humanized allele. These variations demonstrated that alpha-lac expression in mice is gene dosage dependent.
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Affiliation(s)
- A Stacey
- PPL Therapeutics, Edinburgh, Scotland
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27
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Deletion and replacement of the mouse adult beta-globin genes by a "plug and socket" repeated targeting strategy. Mol Cell Biol 1994. [PMID: 7935410 DOI: 10.1128/mcb.14.10.6936] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We describe a two-step strategy to alter any mouse locus repeatedly and efficiently by direct positive selection. Using conventional targeting for the first step, a functional neo gene and a nonfunctional HPRT minigene (the "socket") are introduced into the genome of HPRT- embryonic stem (ES) cells close to the chosen locus, in this case the beta-globin locus. For the second step, a targeting construct (the "plug") that recombines homologously with the integrated socket and supplies the remaining portion of the HPRT minigene is used; this homologous recombination generates a functional HPRT gene and makes the ES cells hypoxanthine-aminopterin-thymidine resistant. At the same time, the plug provides DNA sequences that recombine homologously with sequences in the target locus and modifies them in the desired manner; the plug is designed so that correctly targeted cells also lose the neo gene and become G418 sensitive. We have used two different plugs to make alterations in the mouse beta-globin locus starting with the same socket-containing ES cell line. One plug deleted 20 kb of DNA containing the two adult beta-globin genes. The other replaced the same region with the human beta-globin gene containing the mutation responsible for sickle cell anemia.
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28
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Detloff PJ, Lewis J, John SW, Shehee WR, Langenbach R, Maeda N, Smithies O. Deletion and replacement of the mouse adult beta-globin genes by a "plug and socket" repeated targeting strategy. Mol Cell Biol 1994; 14:6936-43. [PMID: 7935410 PMCID: PMC359224 DOI: 10.1128/mcb.14.10.6936-6943.1994] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
We describe a two-step strategy to alter any mouse locus repeatedly and efficiently by direct positive selection. Using conventional targeting for the first step, a functional neo gene and a nonfunctional HPRT minigene (the "socket") are introduced into the genome of HPRT- embryonic stem (ES) cells close to the chosen locus, in this case the beta-globin locus. For the second step, a targeting construct (the "plug") that recombines homologously with the integrated socket and supplies the remaining portion of the HPRT minigene is used; this homologous recombination generates a functional HPRT gene and makes the ES cells hypoxanthine-aminopterin-thymidine resistant. At the same time, the plug provides DNA sequences that recombine homologously with sequences in the target locus and modifies them in the desired manner; the plug is designed so that correctly targeted cells also lose the neo gene and become G418 sensitive. We have used two different plugs to make alterations in the mouse beta-globin locus starting with the same socket-containing ES cell line. One plug deleted 20 kb of DNA containing the two adult beta-globin genes. The other replaced the same region with the human beta-globin gene containing the mutation responsible for sickle cell anemia.
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Affiliation(s)
- P J Detloff
- Department of Pathology, University of North Carolina, Chapel Hill 27599
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29
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Stinnakre MG, Vilotte JL, Soulier S, Mercier JC. Creation and phenotypic analysis of alpha-lactalbumin-deficient mice. Proc Natl Acad Sci U S A 1994; 91:6544-8. [PMID: 8022817 PMCID: PMC44239 DOI: 10.1073/pnas.91.14.6544] [Citation(s) in RCA: 115] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
alpha-Lactalbumin is an abundant milk-specific calcium metalloprotein which has an evolutionary relationship to lysozyme. It modifies the substrate specificity of a Golgi galactosyltransferase by forming the lactose synthetase binary complex. Lactose, together with other sugars and diffusible ions, is responsible for the osmotic pressure of milk. To assess the involvement of alpha-lactalbumin in lactogenesis, alpha-lactalbumin-deficient mice were created by disrupting the gene by homologous recombination in embryonic stem cells. Homozygous mutant mice are viable and fertile but females cannot feed their offspring. They produce a highly viscous milk that pups appear to be unable to remove from the mammary gland. This milk is rich in fat and protein and is devoid of alpha-lactalbumin and lactose. The phenotype of heterozygous mice was found to be intermediate, with a 40% decrease in alpha-lactalbumin but only a 10-20% decrease in the lactose content of their milk compared with wild-type animals. These results emphasize the key function of alpha-lactalbumin in lactogenesis and open new opportunities to manipulate milk composition.
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MESH Headings
- Animals
- Blotting, Northern
- Blotting, Southern
- Chimera
- Crosses, Genetic
- Embryo, Mammalian
- Female
- Fertility
- Genetic Vectors
- Heterozygote
- Homozygote
- Lactalbumin/biosynthesis
- Lactalbumin/genetics
- Lactation
- Male
- Mammary Glands, Animal/cytology
- Mammary Glands, Animal/metabolism
- Mice
- Mice, Inbred BALB C
- Mice, Inbred CBA
- Mice, Mutant Strains
- Phenotype
- Pregnancy
- Recombination, Genetic
- Restriction Mapping
- Stem Cells/metabolism
- Stem Cells/physiology
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Affiliation(s)
- M G Stinnakre
- Laboratoire de Génétique Biochimique et de Cytogénétique, Institut National de la Recherche Agronomique, Jouy-en-Josas, France
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