101
|
Renal tubular HIF-2α expression requires VHL inactivation and causes fibrosis and cysts. PLoS One 2012; 7:e31034. [PMID: 22299048 PMCID: PMC3267769 DOI: 10.1371/journal.pone.0031034] [Citation(s) in RCA: 68] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2011] [Accepted: 12/29/2011] [Indexed: 01/01/2023] Open
Abstract
The Hypoxia-inducible transcription Factor (HIF) represents an important adaptive mechanism under hypoxia, whereas sustained activation may also have deleterious effects. HIF activity is determined by the oxygen regulated α-subunits HIF-1α or HIF-2α. Both are regulated by oxygen dependent degradation, which is controlled by the tumor suppressor “von Hippel-Lindau” (VHL), the gatekeeper of renal tubular growth control. HIF appears to play a particular role for the kidney, where renal EPO production, organ preservation from ischemia-reperfusion injury and renal tumorigenesis are prominent examples. Whereas HIF-1α is inducible in physiological renal mouse, rat and human tubular epithelia, HIF-2α is never detected in these cells, in any species. In contrast, distinct early lesions of biallelic VHL inactivation in kidneys of the hereditary VHL syndrome show strong HIF-2α expression. Furthermore, knockout of VHL in the mouse tubular apparatus enables HIF-2α expression. Continuous transgenic expression of HIF-2α by the Ksp-Cadherin promotor leads to renal fibrosis and insufficiency, next to multiple renal cysts. In conclusion, VHL appears to specifically repress HIF-2α in renal epithelia. Unphysiological expression of HIF-2α in tubular epithelia has deleterious effects. Our data are compatible with dedifferentiation of renal epithelial cells by sustained HIF-2α expression. However, HIF-2α overexpression alone is insufficient to induce tumors. Thus, our data bear implications for renal tumorigenesis, epithelial differentiation and renal repair mechanisms.
Collapse
|
102
|
Anders K, Buschow C, Charo J, Blankenstein T. Depot formation of doxycycline impairs Tet-regulated gene expression in vivo. Transgenic Res 2011; 21:1099-107. [PMID: 22167485 DOI: 10.1007/s11248-011-9580-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2011] [Accepted: 11/30/2011] [Indexed: 01/26/2023]
Abstract
The tetracycline (Tet) system is widely used for regulation of gene expression in vitro and in vivo. We constructed C57BL/6 transgenic mice (rtTA-CM2) with strong and ubiquitous reverse transactivator (rtTA2(S)-M2) gene expression. rtTA-CM2 mice were crossed to Tet-responsive reporter mice (LC-1) conditionally expressing the firefly luciferase (FLuc) gene under control of a Tet-responsive element, which allowed sensitive quantification of the transactivator activity by bioluminescent imaging. Following doxycycline (dox) application, up to 10(5)-fold increase in BL signal was measured. rtTA activity was inducible in most analyzed organs. After dox withdrawal the BL signal decreased significantly but did not disappear completely, most likely due to a dox depot formation in vivo. The residual dox was sufficient to partly down-regulate a Tet-off controlled oncogene in a tumor transplantation experiment, resulting in reduced tumor growth. rtTA-CM2 mice may be a useful tool to analyze the function of genes in various organs but also reveal that down-regulation of gene expression is not complete.
Collapse
MESH Headings
- Animals
- Antigens, Polyomavirus Transforming/genetics
- Antigens, Polyomavirus Transforming/metabolism
- Antineoplastic Agents/pharmacology
- Crosses, Genetic
- Doxycycline/pharmacology
- Drug Screening Assays, Antitumor/methods
- Founder Effect
- Gene Expression Regulation, Neoplastic
- Luciferases/genetics
- Luciferases/metabolism
- Luminescent Measurements
- Mice
- Mice, Inbred C57BL
- Mice, Transgenic
- Microinjections
- Oncogene Proteins, Fusion/genetics
- Oncogene Proteins, Fusion/metabolism
- Oocytes/metabolism
- Promoter Regions, Genetic
- Simian virus 40/genetics
- Tandem Mass Spectrometry
- Trans-Activators/genetics
- Trans-Activators/metabolism
- Transcription, Genetic
- Transgenes
Collapse
Affiliation(s)
- Kathleen Anders
- Max-Delbrück-Center for Molecular Medicine, Robert-Rössle-Strasse 10, 13125, Berlin, Germany
| | | | | | | |
Collapse
|
103
|
Malato Y, Naqvi S, Schürmann N, Ng R, Wang B, Zape J, Kay MA, Grimm D, Willenbring H. Fate tracing of mature hepatocytes in mouse liver homeostasis and regeneration. J Clin Invest 2011; 121:4850-60. [PMID: 22105172 DOI: 10.1172/jci59261] [Citation(s) in RCA: 321] [Impact Index Per Article: 24.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2011] [Accepted: 10/12/2011] [Indexed: 01/01/2023] Open
Abstract
Recent evidence has contradicted the prevailing view that homeostasis and regeneration of the adult liver are mediated by self duplication of lineage-restricted hepatocytes and biliary epithelial cells. These new data suggest that liver progenitor cells do not function solely as a backup system in chronic liver injury; rather, they also produce hepatocytes after acute injury and are in fact the main source of new hepatocytes during normal hepatocyte turnover. In addition, other evidence suggests that hepatocytes are capable of lineage conversion, acting as precursors of biliary epithelial cells during biliary injury. To test these concepts, we generated a hepatocyte fate-tracing model based on timed and specific Cre recombinase expression and marker gene activation in all hepatocytes of adult Rosa26 reporter mice with an adenoassociated viral vector. We found that newly formed hepatocytes derived from preexisting hepatocytes in the normal liver and that liver progenitor cells contributed minimally to acute hepatocyte regeneration. Further, we found no evidence that biliary injury induced conversion of hepatocytes into biliary epithelial cells. These results therefore restore the previously prevailing paradigms of liver homeostasis and regeneration. In addition, our new vector system will be a valuable tool for timed, efficient, and specific loop out of floxed sequences in hepatocytes.
Collapse
Affiliation(s)
- Yann Malato
- Eli and Edythe Broad Center of Regeneration Medicine and Stem Cell Research, UCSF, San Francisco, California, USA
| | | | | | | | | | | | | | | | | |
Collapse
|
104
|
Theilig F, Enke AK, Scolari B, Polzin D, Bachmann S, Koesters R. Tubular deficiency of von Hippel-Lindau attenuates renal disease progression in anti-GBM glomerulonephritis. THE AMERICAN JOURNAL OF PATHOLOGY 2011; 179:2177-88. [PMID: 21925138 DOI: 10.1016/j.ajpath.2011.07.012] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/16/2011] [Revised: 06/14/2011] [Accepted: 07/06/2011] [Indexed: 01/05/2023]
Abstract
In many kidney diseases, the original insult primarily involves the glomerulus and may then pass onto the tubulointerstitium. Several hypotheses link glomerular disease to tubular injury; perhaps the foremost hypothesis involves chronic tubular hypoxia. The reported effects of hypoxia and consecutive stabilization of hypoxia-inducible factors (HIFs), however, are controversial. Hypoxia induces interstitial fibrosis but also has beneficial effects on renal disease progression when HIF is activated pharmacologically. To analyze the impact of HIF on tubulointerstitial disease development in primary glomerular disease, transgenic von Hippel Lindau (VHL)-knockout mice were generated and null expression was induced before the onset of autoimmune IgG-mediated anti-glomerular basement membrane glomerulonephritis (GN). Tubular VHL knockout and, thus, local HIF-α stabilization increased renal production of vascular endothelial growth factor, tumor growth factor-β(1), and platelet-derived growth factor-B, resulting in augmented formation of capillaries and interstitial matrix, and conversion of fibroblasts to myofibroblasts. Within the glomerular disease, VHL knockout reduced the glomerular damage and attenuated tubulointerstitial injury. Likewise, proteinuria, plasma urea concentration, and tubulointerstitial matrix were decreased in VHL knockout with GN. These findings shown that tubular HIF-α stabilization in glomerular disease is beneficial for disease outcome. In comparison with VHL knockout alone, GN is a much stronger activator of fibrosis such that stimuli other than hypoxia may be considered important for renal disease progression.
Collapse
Affiliation(s)
- Franziska Theilig
- Institute of Anatomy, University of Fribourg, Switzerland; Institute of Anatomy, Charité-Universitätsmedizin, Berlin, Germany.
| | | | | | | | | | | |
Collapse
|
105
|
Smeets B, Kuppe C, Sicking EM, Fuss A, Jirak P, van Kuppevelt TH, Endlich K, Wetzels JFM, Gröne HJ, Floege J, Moeller MJ. Parietal epithelial cells participate in the formation of sclerotic lesions in focal segmental glomerulosclerosis. J Am Soc Nephrol 2011; 22:1262-74. [PMID: 21719782 DOI: 10.1681/asn.2010090970] [Citation(s) in RCA: 170] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
The pathogenesis of the development of sclerotic lesions in focal segmental glomerulosclerosis (FSGS) remains unknown. Here, we selectively tagged podocytes or parietal epithelial cells (PECs) to determine whether PECs contribute to sclerosis. In three distinct models of FSGS (5/6-nephrectomy + DOCA-salt; the murine transgenic chronic Thy1.1 model; or the MWF rat) and in human biopsies, the primary injury to induce FSGS associated with focal activation of PECs and the formation of cellular adhesions to the capillary tuft. From this entry site, activated PECs invaded the affected segment of the glomerular tuft and deposited extracellular matrix. Within the affected segment, podocytes were lost and mesangial sclerosis developed within the endocapillary compartment. In conclusion, these results demonstrate that PECs contribute to the development and progression of the sclerotic lesions that define FSGS, but this pathogenesis may be relevant to all etiologies of glomerulosclerosis.
Collapse
Affiliation(s)
- Bart Smeets
- Department of Nephrology and Clinical Immunology, RWTH University Hospital Aachen, Pauwelsstr. 30, 52074 Aachen, Germany
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
106
|
Metzger D, Chambon P. Generation of Spatio-Temporally Controlled Targeted Somatic Mutations in the Mouse. CURRENT PROTOCOLS IN MOUSE BIOLOGY 2011; 1:55-70. [PMID: 26068987 DOI: 10.1002/9780470942390.mo100128] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The generation of ligand-activated site-specific Cre recombinases has led to the development of cell type-specific temporally controlled targeted somatic mutagenesis in the mouse. We illustrate this technique using K14-Cre-ER(T2) transgenic mice that express the tamoxifen (tam)-activatable Cre-ER(T2) recombinase in epidermal basal keratinocytes to induce mutations in epidermal keratinocytes of adult mice. Our highly reproducible technique, based on induction of Cre-ER(T2) recombinase activity by tamoxifen administration at low doses (once daily 100-µg intraperitoneal injection for 5 days), has allowed the generation of site-directed somatic mutations of numerous genes in mouse epidermal keratinocytes, and several mouse models of human diseases. The present step-by-step protocol describes how to introduce temporally controlled targeted mutations in epidermal keratinocytes of adult mice. Curr. Protoc. Mouse Biol. 1:55-70. © 2011 by John Wiley & Sons, Inc.
Collapse
Affiliation(s)
- Daniel Metzger
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, Université de Strasbourg, and Collège de France, Illkirch, France
| | - Pierre Chambon
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, Université de Strasbourg, and Collège de France, Illkirch, France
| |
Collapse
|
107
|
Endothelial focal adhesion kinase mediates cancer cell homing to discrete regions of the lungs via E-selectin up-regulation. Proc Natl Acad Sci U S A 2011; 108:3725-30. [PMID: 21321210 DOI: 10.1073/pnas.1100446108] [Citation(s) in RCA: 141] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Primary tumors secrete factors that alter the microenvironment of distant organs, rendering those organs as fertile soil for subsequent metastatic cancer cell colonization. Although the lungs are exposed to these factors ubiquitously, lung metastases usually develop as a series of discrete lesions. The underlining molecular mechanisms of the formation of these discrete lesions are not understood. Here we show that primary tumors induce formation of discrete foci of vascular hyperpermeability in premetastatic lungs. This is mediated by endothelial cell-focal adhesion kinase (FAK), which up-regulates E-selectin, leading to preferential homing of metastatic cancer cells to these foci. Suppression of endothelial-FAK or E-selectin activity attenuates the number of cancer cells homing to these foci. Thus, localized activation of endothelial FAK and E-selectin in the lung vasculature mediates the initial homing of metastatic cancer cells to specific foci in the lungs.
Collapse
|
108
|
Weber T, Baier V, Pauly R, Sahay A, Baur M, Herrmann E, Ciccolini F, Hen R, Kronenberg G, Bartsch D. Inducible gene expression in GFAP+ progenitor cells of the SGZ and the dorsal wall of the SVZ-A novel tool to manipulate and trace adult neurogenesis. Glia 2011; 59:615-26. [PMID: 21294160 DOI: 10.1002/glia.21129] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2010] [Accepted: 11/25/2010] [Indexed: 01/07/2023]
Abstract
In the adult mammalian brain, neurogenesis originates from astrocyte-like stem cells. We generated a transgenic mouse line in which the tetracycline dependent transactivator (tTA) is expressed under the control of the murine GFAP promoter. In this mouse line, inducible gene expression targets virtually all GFAP-expressing stem-like cells in the dentate gyrus and a subset of GFAP-expressing progenitors located primarily in the dorsal wall/dorsolateral corner of the subventricular zone. Outside the neurogenic zones, astrocytes are infrequently targeted. We introduce a panel of transgenic mice which allow both inducible expression of candidate genes under control of the murine GFAP promoter and, at the same time, lineage tracing of all cells descendant from the original GFAP-positive cell. This new mouse line represents a versatile tool for functional analysis of neurogenesis and lineage tracing.
Collapse
Affiliation(s)
- Tillmann Weber
- Department of Molecular Biology, Central Institute of Mental Health, Heidelberg University, Medical Faculty Mannheim, Mannheim, Germany
| | | | | | | | | | | | | | | | | | | |
Collapse
|
109
|
Ueberham E, Böttger J, Ueberham U, Grosche J, Gebhardt R. Response of sinusoidal mouse liver cells to choline-deficient ethionine-supplemented diet. COMPARATIVE HEPATOLOGY 2010; 9:8. [PMID: 20942944 PMCID: PMC2964607 DOI: 10.1186/1476-5926-9-8] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/11/2010] [Accepted: 10/13/2010] [Indexed: 01/10/2023]
Abstract
BACKGROUND Proliferation of oval cells, the bipotent precursor cells of the liver, requires impeded proliferation and loss of hepatocytes as well as a specific micro-environment, provided by adjacent sinusoidal cells of liver. Despite their immense importance for triggering the oval cell response, cells of hepatic sinusoids are rarely investigated. To elucidate the response of sinusoidal liver cells we have employed a choline-deficient, ethionine-supplemented (CDE) diet, a common method for inducing an oval cell response in rodent liver. We have utilised selected expression markers commonly used in the past for phenotypic discrimination of oval cells and sinusoidal cells: cytokeratin, E-cadherin and M2-pyruvate kinase for oval cells; and glial fibrillary acidic protein (GFAP) was used for hepatic stellate cells (HSCs). RESULTS CDE diet leads to an activation of all cells of the hepatic sinusoid in the mouse liver. Beside oval cells, also HSCs and Kupffer cells proliferate. The entire fraction of proliferating cells in mouse liver as well as endothelial cells and cholangiocytes express M2-pyruvate kinase. Concomitantly, GFAP, long considered a unique marker of quiescent HSCs was upregulated in activated HSCs and expressed also in cholangiocytes and oval cells. CONCLUSIONS Our results point to an important role of all types of sinusoidal cells in regeneration from CDE induced liver damage and call for utmost caution in using traditional marker for identifying specific cell types. Thus, M2-pyruvate kinase should no longer be used for estimating the oval cell response in mouse liver. CDE diet leads to activation of GFAP positive HSCs in the pericentral zone of liver lobulus. In the periportal zone the detection of GFAP in biliary cells and oval cells, calls other cell types as progenitors of hepatocytes into question under CDE diet conditions.
Collapse
Affiliation(s)
- Elke Ueberham
- Institute of Biochemistry, Medical Faculty, University of Leipzig, Leipzig, Germany.
| | | | | | | | | |
Collapse
|
110
|
Sawa S, Cherrier M, Lochner M, Satoh-Takayama N, Fehling HJ, Langa F, Di Santo JP, Eberl G. Lineage relationship analysis of RORgammat+ innate lymphoid cells. Science 2010; 330:665-9. [PMID: 20929731 DOI: 10.1126/science.1194597] [Citation(s) in RCA: 412] [Impact Index Per Article: 29.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Lymphoid tissue-inducer (LTi) cells initiate the development of lymphoid tissues through the activation of local stromal cells in a process similar to inflammation. LTi cells express the nuclear hormone receptor RORγt, which also directs the expression of the proinflammatory cytokine interleukin-17 in T cells. We show here that LTi cells are part of a larger family of proinflammatory RORγt(+) innate lymphoid cells (ILCs) that differentiate from distinct fetal liver RORγt(+) precursors. The fate of RORγt(+) ILCs is determined by mouse age, and after birth, favors the generation of cells involved in intestinal homeostasis and defense. Contrary to RORγt(+) T cells, however, RORγt(+) ILCs develop in the absence of microbiota. Our study indicates that RORγt(+) ILCs evolve to preempt intestinal colonization by microbial symbionts.
Collapse
Affiliation(s)
- Shinichiro Sawa
- Lymphoid Tissue Development Unit, Institut Pasteur, 75724 Paris, France
| | | | | | | | | | | | | | | |
Collapse
|
111
|
Grabner B, Blaas L, Musteanu M, Hoffmann T, Birbach A, Eferl R, Casanova E. A mouse tool for conditional mutagenesis in ovarian granulosa cells. Genesis 2010; 48:612-7. [DOI: 10.1002/dvg.20664] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
|
112
|
Koesters R, Kaissling B, Lehir M, Picard N, Theilig F, Gebhardt R, Glick AB, Hähnel B, Hosser H, Gröne HJ, Kriz W. Tubular overexpression of transforming growth factor-beta1 induces autophagy and fibrosis but not mesenchymal transition of renal epithelial cells. THE AMERICAN JOURNAL OF PATHOLOGY 2010; 177:632-43. [PMID: 20616344 PMCID: PMC2913362 DOI: 10.2353/ajpath.2010.091012] [Citation(s) in RCA: 232] [Impact Index Per Article: 16.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 04/21/2010] [Indexed: 01/05/2023]
Abstract
We recently showed in a tetracycline-controlled transgenic mouse model that overexpression of transforming growth factor (TGF)-beta1 in renal tubules induces widespread peritubular fibrosis and focal degeneration of nephrons. In the present study we have analyzed the mechanisms underlying these phenomena. The initial response to tubular cell-derived TGF-beta1 consisted of a robust proliferation of peritubular cells and deposition of collagen. On sustained expression, nephrons degenerated in a focal pattern. This process started with tubular dedifferentiation and proceeded to total decomposition of tubular cells by autophagy. The final outcome was empty collapsed remnants of tubular basement membrane embedded into a dense collagenous fibrous tissue. The corresponding glomeruli survived as atubular remnants. Thus, TGF-beta1 driven autophagy may represent a novel mechanism of tubular decomposition. The fibrosis seen in between intact tubules and in areas of tubular decomposition resulted from myofibroblasts that were derived from local fibroblasts. No evidence was found for a transition of tubular cells into myofibroblasts. Neither tracing of injured tubules in electron micrographs nor genetic tagging of tubular epithelial cells revealed cells transgressing the tubular basement membrane. In conclusion, overexpression of TGF-beta1 in renal tubules in vivo induces interstitial proliferation, tubular autophagy, and fibrosis, but not epithelial-to-mesenchymal transition.
Collapse
Affiliation(s)
- Robert Koesters
- Institute of Human Genetics, University of Heidelberg, Heidelberg, Germany
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
113
|
Development of a BAC vector for integration-independent and tight regulation of transgenes in rodents via the Tet system. Transgenic Res 2010; 20:709-20. [PMID: 20640885 DOI: 10.1007/s11248-010-9427-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2010] [Accepted: 07/03/2010] [Indexed: 01/02/2023]
Abstract
The establishment of functional transgenic mouse lines is often limited by problems caused by integration site effects on the expression construct. Similarly, tetracycline (Tet) controlled transcription units most commonly used for conditional transgene expression in mice are strongly influenced by their genomic surrounding. Using bacterial artificial chromosome (BAC) technology in constitutive expression systems, it has been shown that integration site effects resulting in unwanted expression patterns can be largely eliminated. Here we describe a strategy to minimize unfavourable integration effects on conditional expression constructs based on a 75 kb genomic BAC fragment. This fragment was derived from a transgenic mouse line, termed LC-1, which carries the Tet-inducible genes luciferase and cre (Schönig et al. 2002). Animals of this mouse line have previously been shown to exhibit optimal expression properties in terms of tightness in the off state and the absolute level of induction, when mated to appropriate transactivator expressing mice. Here we report the cloning and identification of the transgenic LC-1 integration site which was subsequently inserted into a bacterial artificial chromosome. We demonstrate that this vector facilitates the efficient generation of transgenic mouse and rat lines, where the Tet-controlled expression unit is shielded from perturbations caused by the integration site.
Collapse
|
114
|
Duerr J, Gruner M, Schubert SC, Haberkorn U, Bujard H, Mall MA. Use of a new-generation reverse tetracycline transactivator system for quantitative control of conditional gene expression in the murine lung. Am J Respir Cell Mol Biol 2010; 44:244-54. [PMID: 20395635 DOI: 10.1165/rcmb.2009-0115oc] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Conditional regulation of gene expression by the combined use of a lung-specific promoter and the tetracycline-regulated system provides a powerful tool for studying gene function in lung biology and disease pathogenesis in a development-independent fashion. However, the original version of the reverse tetracycline-dependent transactivator (rtTA) exhibited limited doxycycline sensitivity and residual affinity to its promoter (P(tet)), producing leaky transgene expression in the absence of doxycycline. These limitations impeded the use of this system in studying gene dosage effects in pulmonary pathogenesis and repair mechanisms in the diseased lung. Therefore, we used a new-generation rtTA, rtTA2(s)-M2, with no basal activity and increased doxycycline sensitivity, and the rat Clara cell secretory protein (CCSP) promoter to target its expression to pulmonary epithelia in mice. Novel CCSP-rtTA2(s)-M2 founder lines were crossed, with bi-transgenic reporter mice expressing luciferase and Cre recombinase. Background activity, doxycycline sensitivity, tissue and cell-type specificity, inducibility, and reversibility of doxycycline-dependent gene expression were determined by luciferase activity, immunohistochemistry, morphometry, and bioluminescence measurements in neonatal and adult lungs. We generated two distinct novel CCSP-rtTA2(s)-M2 activator mouse lines that confer tight and doxycycline dose-dependent regulation of transgene expression, with high inducibility, complete reversibility, and no background activity, in airway and alveolar epithelia. We conclude that rtTA2(s)-M2 enables quantitative control of conditional gene expression in respiratory epithelia of the murine lung, and that the new CCSP-rtTA2(s)-M2 activator mouse lines will be useful in the further elucidation of the pathogenesis of complex lung diseases and in studies of lung repair.
Collapse
Affiliation(s)
- Julia Duerr
- Division of Pediatric Pulmonology, Cystic Fibrosis Center, Department of Pediatrics III, University of Heidelberg, Germany
| | | | | | | | | | | |
Collapse
|
115
|
Interference RNA for in vivo Knock-down of gene expression or genome-wide screening using shRNA. Methods Mol Biol 2010; 597:189-209. [PMID: 20013235 DOI: 10.1007/978-1-60327-389-3_14] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/10/2023]
Abstract
With the lack of tools available to manipulate the rat genome, alternative technologies have been investigated to generate loss-of-function rat models by gene invalidation. The recent demonstration that RNA interference (RNAi)-mediated gene silencing occurs in rodents has opened new opportunities for rat functional genetics. In this chapter, we provide some practical guidelines for RNAi working in rat, based on the recent design and development of mice and rat Knock down models.
Collapse
|
116
|
Pullirsch D, Härtel R, Kishimoto H, Leeb M, Steiner G, Wutz A. The Trithorax group protein Ash2l and Saf-A are recruited to the inactive X chromosome at the onset of stable X inactivation. Development 2010; 137:935-43. [PMID: 20150277 DOI: 10.1242/dev.035956] [Citation(s) in RCA: 103] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Mammals compensate X chromosome gene dosage between the sexes by silencing of one of the two female X chromosomes. X inactivation is initiated in the early embryo and requires the non-coding Xist RNA, which encompasses the inactive X chromosome (Xi) and triggers its silencing. In differentiated cells, several factors including the histone variant macroH2A and the scaffold attachment factor SAF-A are recruited to the Xi and maintain its repression. Consequently, in female somatic cells the Xi remains stably silenced independently of Xist. Here, we identify the Trithorax group protein Ash2l as a novel component of the Xi. Ash2l is recruited by Xist concomitantly with Saf-A and macroH2A at the transition to Xi maintenance. Recruitment of these factors characterizes a developmental transition point for the chromatin composition of the Xi. Surprisingly, expression of a mutant Xist RNA that does not cause gene repression can trigger recruitment of Ash2l, Saf-A and macroH2A to the X chromosome, and can cause chromosome-wide histone H4 hypoacetylation. This suggests that a chromatin configuration is established on non-genic chromatin on the Xi by Xist to provide a repressive compartment that could be used for maintaining gene silencing. Gene silencing is mechanistically separable from the formation of this repressive compartment and, thus, requires additional pathways. This observation highlights a crucial role for spatial organization of chromatin changes in the maintenance of X inactivation.
Collapse
Affiliation(s)
- Dieter Pullirsch
- Research Institute of Molecular Pathology, Dr Bohr-Gasse 7, 1030 Vienna, Austria
| | | | | | | | | | | |
Collapse
|
117
|
Boross P, Breukel C, van Loo PF, van der Kaa J, Claassens JW, Bujard H, Schönig K, Verbeek JS. Highly B lymphocyte-specific tamoxifen inducible transgene expression of CreER T2 by using the LC-1 locus BAC vector. Genesis 2010; 47:729-35. [PMID: 19621440 DOI: 10.1002/dvg.20549] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
The generation of cell type specific inducible Cre transgenic mice is the most challenging and limiting part in the development of spatio-temporally controlled knockout mouse models. Here we report the generation and characterization of a B lymphocyte-specific tamoxifen-inducible Cre transgenic mouse strain, LC-1-hCD19-CreER(T2). We utilized the human CD19 promoter for expression of the tamoxifen-inducible Cre recombinase (CreER(T2)) gene, embedded in genomic sequences previously reported to give minimal position effects after transgenesis. Cre recombinase activity was evaluated by cross-breeding the LC-1-hCD19-CreER(T2) strain with a strain containing a floxed gene widely expressed in the hematopoietic system. Cre activity was only detected in the presence of tamoxifen and was restricted to B lymphocytes. The efficacy of recombination ranged from 27 to 61% in the hemizygous and homozygous mice, respectively. In conclusion, the LC-1-hCD19-CreER(T2) strain is a powerful tool to study gene function specifically in B lymphocytes at any chosen time point in the lifecycle of the mouse.
Collapse
Affiliation(s)
- Peter Boross
- Department of Human and Clinical Genetics, Leiden University Medical Center, Leiden, The Netherlands
| | | | | | | | | | | | | | | |
Collapse
|
118
|
The power of reversibility regulating gene activities via tetracycline-controlled transcription. Methods Enzymol 2010; 477:429-53. [PMID: 20699154 DOI: 10.1016/s0076-6879(10)77022-1] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Tetracycline-controlled transcriptional activation systems are widely used to control gene expression in transgenic animals in a truly conditional manner. By this we refer to the capability of these expression systems to control gene activities not only in a tissue specific and temporal defined but also reversible manner. This versatility has made the Tet regulatory systems to a preeminent tool in reverse mouse genetics. The development of the technology in the past 15 years will be reviewed and guidelines will be given for its implementation in creating transgenic rodents. Finally, we highlight some recent exciting applications of the Tet technology as well as its foreseeable combination with other emerging technologies in mouse transgenesis.
Collapse
|
119
|
Abstract
Within the past 10 years, RNA interference has emerged as a powerful experimental tool as it allows rapid gene function analysis. Unique features such as reversibility of gene silencing and simultaneous targeting of several genes characterize the approach. In this chapter, transgenic RNAi techniques in reverse mouse genetics are discussed and protocols are provided.
Collapse
|
120
|
A Practical Summary of Site-Specific Recombination, Conditional Mutagenesis, and Tamoxifen Induction of CreERT2. Methods Enzymol 2010; 477:109-23. [DOI: 10.1016/s0076-6879(10)77007-5] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
|
121
|
Abstract
In 1991, Soriano and coworkers isolated the ROSA26 locus in a gene-trap mutagenesis screening performed in mouse embryonic stem (ES) cells. The ubiquitous expression of ROSA26 in embryonic and adult tissues, together with the high frequency of gene-targeting events observed at this locus in murine ES cells has led to the establishment in the past 10 years of over 130 knock-in lines expressing successfully from the ROSA26 locus a variety of transgenes including reporters, site-specific recombinases and, recently, noncoding RNAs. Different strategies can be employed to drive transgene expression from the ROSA26 locus. This chapter provides an overview of the current methodologies used to generate ROSA26 knock-in lines and describes different approaches that exploit the ROSA26 gene to control expression of transgenes, including miRNAs, in a temporal, cell-type, and stage-specific fashion.
Collapse
Affiliation(s)
- Stefano Casola
- IFOM, The FIRC Institute of Molecular Oncology Foundation, Milan, Italy
| |
Collapse
|
122
|
New mouse lines for the analysis of neuronal morphology using CreER(T)/loxP-directed sparse labeling. PLoS One 2009; 4:e7859. [PMID: 19924248 PMCID: PMC2775668 DOI: 10.1371/journal.pone.0007859] [Citation(s) in RCA: 77] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2009] [Accepted: 10/20/2009] [Indexed: 12/30/2022] Open
Abstract
Background Pharmacologic control of Cre-mediated recombination using tamoxifen-dependent activation of a Cre-estrogen receptor ligand binding domain fusion protein [CreER(T)] is widely used to modify and/or visualize cells in the mouse. Methods and Findings We describe here two new mouse lines, constructed by gene targeting to the Rosa26 locus to facilitate Cre-mediated cell modification. These lines should prove particularly useful in the context of sparse labeling experiments. The R26rtTACreER line provides ubiquitous expression of CreER under transcriptional control by the tetracycline reverse transactivator (rtTA); dual control by doxycycline and tamoxifen provides an extended dynamic range of Cre-mediated recombination activity. The R26IAP line provides high efficiency Cre-mediated activation of human placental alkaline phosphatase (hPLAP), complementing the widely used, but low efficiency, Z/AP line. By crossing with mouse lines that direct cell-type specific CreER expression, the R26IAP line has been used to produce atlases of labeled cholinergic and catecholaminergic neurons in the mouse brain. The R26IAP line has also been used to visualize the full morphologies of retinal dopaminergic amacrine cells, among the largest neurons in the mammalian retina. Conclusions The two new mouse lines described here expand the repertoire of genetically engineered mice available for controlled in vivo recombination and cell labeling using the Cre-lox system.
Collapse
|
123
|
Kumar TR. FSHbeta knockout mouse model: a decade ago and into the future. Endocrine 2009; 36:1-5. [PMID: 19387872 PMCID: PMC4074305 DOI: 10.1007/s12020-009-9199-6] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/18/2009] [Revised: 02/24/2009] [Accepted: 04/09/2009] [Indexed: 10/20/2022]
Abstract
In 1997, more than 10 years ago now, we first reported the phenotypes of follicle stimulating hormone (FSH) beta null mice. Since then, these mice have been useful for various physiological and genetic studies in reproductive biology. More recently, extra-gonadal functions of FSH have been discovered in bone. These studies opened up exciting avenues of new research on osteoporosis in postmenopausal women. Several genomics and proteomics tools and novel strategies to spatio-temporally restricting gene expression in vivo are available now. It is hoped that with the aid of these and other emerging technologies, an integrated network of FSH signaling pathways in various tissues would emerge in the near future. Undoubtedly, the coming 10 years should be more exciting to explore this "fertile" area of reproductive physiology research.
Collapse
Affiliation(s)
- T Rajendra Kumar
- Department of Molecular, University of Kansas Medical Center, Kansas City, KS 66160, USA.
| |
Collapse
|
124
|
Carlone DL. Functional analysis of adult stem cells using Cre-mediated lineage tracing. CURRENT PROTOCOLS IN STEM CELL BIOLOGY 2009; Chapter 5:Unit 5A.2. [PMID: 19455543 DOI: 10.1002/9780470151808.sc05a02s9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Lineage-tracing has been used for decades to establish cell fate maps during development. Recently, with the advent of genetic lineage-tracing techniques (employing Cre-lox recombination), it has been possible to permanently mark progenitor/stem cell populations within somatic tissues. In addition, pulse-chase studies have shown that only stem cells are capable of producing labeled progeny after an extensive period of chase. This unit focuses on the protocols used to target putative adult stem cells in vivo. Using these techniques, one should be able to functionally confirm or deny the stem cell capacity of a given cell population.
Collapse
Affiliation(s)
- Diana L Carlone
- Children's Hospital Boston, Harvard Medical School, Boston, Massachusetts
| |
Collapse
|
125
|
Doxycycline accelerates renal cyst growth and fibrosis in the pcy/pcy mouse model of type 3 nephronophthisis, a form of recessive polycystic kidney disease. Histochem Cell Biol 2009; 132:199-210. [DOI: 10.1007/s00418-009-0588-y] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/18/2009] [Indexed: 12/11/2022]
|
126
|
Weidenfeld I, Gossen M, Löw R, Kentner D, Berger S, Görlich D, Bartsch D, Bujard H, Schönig K. Inducible expression of coding and inhibitory RNAs from retargetable genomic loci. Nucleic Acids Res 2009; 37:e50. [PMID: 19264799 PMCID: PMC2673444 DOI: 10.1093/nar/gkp108] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Conditional gene expression systems have developed into essential tools for the study of gene functions. However, their utility is often limited by the difficulty of identifying clonal cell lines, in which transgene control can be realized to its full potential. Here, we describe HeLa cell lines, in which we have identified-by functional analysis-genomic loci, from which the expression of transgenes can be tightly controlled via tetracycline-regulated expression. These loci can be re-targeted by recombinase-mediated cassette exchange. Upon exchange of the gene of interest, the resulting cell line exhibits the qualitative and quantitative properties of controlled transgene expression characteristic for the parent cell line. Moreover, by using an appropriate promoter, these cell lines express the tetracycline controlled transcription activator rtTA2-M2 uniformly throughout the entire cell population. The potential of this approach for functional genomics is highlighted by utilizing one of our master cell lines for the efficient microRNA-mediated knockdown of the endogenous human lamin A/C gene.
Collapse
|
127
|
Abstract
Chromosomal rearrangements, such as deletions, duplications, inversions and translocations, occur frequently in humans and can be disease-associated or phenotypically neutral. To understand the genetic consequences of such genomic changes, these mutations need to be modelled in experimentally tractable systems. The mouse is an excellent organism for this analysis because of its biological and genetic similarity to humans, the ease with which its genome can be manipulated and the similarity of observed affects. Through chromosome engineering, defined rearrangements can be introduced into the mouse genome. The resulting mouse models are leading to a better understanding of the molecular and cellular basis of dosage alterations in human disease phenotypes, in turn opening new diagnostic and therapeutic opportunities.
Collapse
Affiliation(s)
- Louise van der Weyden
- Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridgeshire, UK
| | | | | |
Collapse
|
128
|
Appel D, Kershaw DB, Smeets B, Yuan G, Fuss A, Frye B, Elger M, Kriz W, Floege J, Moeller MJ. Recruitment of podocytes from glomerular parietal epithelial cells. J Am Soc Nephrol 2008; 20:333-43. [PMID: 19092119 DOI: 10.1681/asn.2008070795] [Citation(s) in RCA: 365] [Impact Index Per Article: 22.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Abstract
Loss of a critical number of podocytes from the glomerular tuft leads to glomerulosclerosis. Even in health, some podocytes are lost into the urine. Because podocytes themselves cannot regenerate, we postulated that glomerular parietal epithelial cells (PECs), which proliferate throughout life and adjoin podocytes, may migrate to the glomerular tuft and differentiate into podocytes. Here, we describe transitional cells at the glomerular vascular stalk that exhibit features of both PECs and podocytes. Metabolic labeling in juvenile rats suggested that PECs migrate to become podocytes. To prove this, we generated triple-transgenic mice that allowed specific and irreversible labeling of PECs upon administration of doxycycline. PECs were followed in juvenile mice beginning from either postnatal day 5 or after nephrogenesis had ceased at postnatal day 10. In both cases, the number of genetically labeled cells increased over time. All genetically labeled cells coexpressed podocyte marker proteins. In conclusion, we demonstrate for the first time recruitment of podocytes from PECs in juvenile mice. Unraveling the mechanisms of PEC recruitment onto the glomerular tuft may lead to novel therapeutic approaches to renal injury.
Collapse
Affiliation(s)
- Daniel Appel
- Division of Nephrology and Immunology, Rheinisch Westfälische Technische Hochschule University of Aachen, Aachen, Germany
| | | | | | | | | | | | | | | | | | | |
Collapse
|
129
|
Rubera I, Hummler E, Beermann F. Transgenic mice and their impact on kidney research. Pflugers Arch 2008; 458:211-22. [PMID: 19084992 DOI: 10.1007/s00424-008-0624-0] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2008] [Accepted: 11/25/2008] [Indexed: 12/12/2022]
Abstract
The kidney is a key organ in the maintenance of ion and fluid homeostasis and specific transport systems localized along the nephron guarantee this function. Due to its large functional heterogeneity, experiments on the whole organ level cannot be easily performed, and thus more refined tools are needed, like for example the development of specific recombination systems to gain knowledge on the physiological role of single proteins implicated in ion transport. This review introduces the transgenic technology developed over the past decades, and then focuses on recent strategies for generating kidney-specific gene targeting, over-expression, and gene ablation in mice, that will help to understand the physiological role of proteins implicated in salt and water balance in the kidney.
Collapse
|
130
|
Chiu C, Reid CA, Tan HO, Davies PJ, Single FN, Koukoulas I, Berkovic SF, Tan SS, Sprengel R, Jones MV, Petrou S. Developmental impact of a familial GABAA receptor epilepsy mutation. Ann Neurol 2008; 64:284-93. [PMID: 18825662 DOI: 10.1002/ana.21440] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
OBJECTIVE A major goal of epilepsy research is to understand the molecular and functional basis of seizure genesis. A human GABA(A) gamma2 gene mutation (R43Q) is associated with generalized epilepsy. Introduction of this mutation into a mouse by gene targeting recapitulates the human phenotype demonstrating a strong genotype to phenotype link. GABA(A) receptors play a role in the moment-to-moment control of brain function and also on the long-term wiring of the brain by directing neuronal development. Our objective was to determine whether developmental expression of the mutation alters seizure susceptibility later in life. METHODS A tetracycline-based conditional model for activation of a hypomorphic Q43 disease allele was created and validated. Seizure susceptibility was assessed using the subcutaneous pentylenetetrazole model. RESULTS Seizure susceptibility was significantly reduced in mice where the Q43 allele was suppressed during development. INTERPRETATION These results demonstrate that a human epilepsy-causing mutation impacts network stability during a critical developmental period. These data suggest that identification of presymptomatic children may provide a window for therapeutic intervention before overt symptoms are observed, potentially altering the course of epileptogenesis.
Collapse
Affiliation(s)
- Cindy Chiu
- Howard Florey Institute, The University of Melbourne, Parkville, Melbourne, Australia
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
131
|
Traykova-Brauch M, Schönig K, Greiner O, Miloud T, Jauch A, Bode M, Felsher DW, Glick AB, Kwiatkowski DJ, Bujard H, Horst J, von Knebel Doeberitz M, Niggli FK, Kriz W, Gröne HJ, Koesters R. An efficient and versatile system for acute and chronic modulation of renal tubular function in transgenic mice. Nat Med 2008; 14:979-84. [PMID: 18724376 DOI: 10.1038/nm.1865] [Citation(s) in RCA: 224] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2007] [Accepted: 02/13/2008] [Indexed: 11/09/2022]
Abstract
We describe a transgenic mouse line, Pax8-rtTA, which, under control of the mouse Pax8 promoter, directs high levels of expression of the reverse tetracycline-dependent transactivator (rtTA) to all proximal and distal tubules and the entire collecting duct system of both embryonic and adult kidneys. Using crosses of Pax8-rtTA mice with tetracycline-responsive c-MYC mice, we established a new, inducible model of polycystic kidney disease that can mimic adult onset and that shows progression to renal malignant disease. When targeting the expression of transforming growth factor beta-1 to the kidney, we avoided early lethality by discontinuous treatment and successfully established an inducible model of renal fibrosis. Finally, a conditional knockout of the gene encoding tuberous sclerosis complex-1 was achieved, which resulted in the early outgrowth of giant polycystic kidneys reminiscent of autosomal recessive polycystic kidney disease. These experiments establish Pax8-rtTA mice as a powerful tool for modeling renal diseases in transgenic mice.
Collapse
Affiliation(s)
- Milena Traykova-Brauch
- Department of Cellular and Molecular Pathology, Deutsches Krebsforschungszentrum, Im Neuenheimer Feld 280, 69120 Heidelberg, Germany
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
132
|
Hendriks G, Calléja F, Vrieling H, Mullenders LH, Jansen JG, de Wind N. Gene transcription increases DNA damage-induced mutagenesis in mammalian stem cells. DNA Repair (Amst) 2008; 7:1330-9. [DOI: 10.1016/j.dnarep.2008.04.015] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2008] [Revised: 04/24/2008] [Accepted: 04/27/2008] [Indexed: 01/04/2023]
|
133
|
Wu Y, He Y, Zhang H, Dai X, Zhou X, Gu J, Wang G, Zhu J. A stringent dual control system overseeing transcription and activity of the Cre recombinase for the liver-specific conditional gene knock-out mouse model. J Genet Genomics 2008; 35:431-9. [DOI: 10.1016/s1673-8527(08)60060-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2008] [Revised: 05/09/2008] [Accepted: 05/10/2008] [Indexed: 11/17/2022]
|
134
|
Pich D, Humme S, Spindler MP, Schepers A, Hammerschmidt W. Conditional gene vectors regulated in cis. Nucleic Acids Res 2008; 36:e83. [PMID: 18566006 PMCID: PMC2490737 DOI: 10.1093/nar/gkn273] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Non-integrating gene vectors, which are stably and extrachromosomally maintained in transduced cells would be perfect tools to support long-term expression of therapeutic genes but preserve the genomic integrity of the cellular host. Small extrachromosomal plasmids share some of these ideal characteristics but are primarily based on virus blueprints. These plasmids are dependent on viral trans-acting factors but they can replicate their DNA molecules in synchrony with the chromosome of the cellular host and segregate to daughter cells in an autonomous fashion. On the basis of the concept of the latent origin of DNA replication of Epstein-Barr virus, oriP, we devised novel derivatives, which exclusively rely on an artificial replication factor for both nuclear retention and replication of plasmid DNA. In addition, an allosteric switch regulates the fate of the plasmid molecules, which are rapidly lost upon addition of doxycycline. Conditional maintenance of these novel plasmid vectors allows the reversible transfer of genetic information into target cells for the first time.
Collapse
Affiliation(s)
- Dagmar Pich
- Department of Gene Vectors, Helmholtz Center Munich, German Research Center for Environmental Health, Marchioninistr. 25, 81377 Munich, Germany
| | | | | | | | | |
Collapse
|
135
|
Bockamp E, Sprengel R, Eshkind L, Lehmann T, Braun JM, Emmrich F, Hengstler JG. Conditional transgenic mouse models: from the basics to genome-wide sets of knockouts and current studies of tissue regeneration. Regen Med 2008; 3:217-35. [DOI: 10.2217/17460751.3.2.217] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Many mouse models are currently available, providing avenues to elucidate gene function and to recapitulate specific pathological conditions. To a large extent, successful translation of clinical evidence or analytical data into appropriate mouse models is possible through progress in transgenic or gene-targeting technology. Beginning with a review of standard mouse transgenics and conventional gene targeting, this article will move on to discussing the basics of conditional gene expression: the tetracycline (tet)-off and tet-on systems based on the transactivators tet-controlled transactivator (Tta) and reverse tet-on transactivator (rtTA) that allow downregulation or induction of gene expression; Cre or Flp recombinase-mediated modifications, including excision, inversion, insertion and interchromosomal translocation; combination of the tet and Cre systems, permitting inducible knockout, reporter gene activation or activation of point mutations; the avian retroviral system based on delivery of rtTA specifically into cells expressing the avian retroviral receptor, which enables cell type-specific, inducible gene expression; the tamoxifen system, one of the most frequently applied steroid receptor-based systems, allows rapid activation of a fusion protein between the gene of interest and a mutant domain of the estrogen receptor, whereby activation does not depend on transcription; and techniques for cell type-specific ablation. The diphtheria toxin receptor system offers the advantage that it can be combined with the ‘zoo’ of Cre recombinase driver mice. Having described the basics we move on to the cutting edge: generation of genome-wide sets of conditional knockout mice. To this end, large ongoing projects apply two strategies: gene trapping based on random integration of trapping vectors into introns leading to truncation of the transcript, and gene targeting, representing the directed approach using homologous recombination. It can be expected that in the near future genome-wide sets of such mice will be available. Finally, the possibilities of conditional expression systems for investigating gene function in tissue regeneration will be illustrated by examples for neurodegenerative disease, liver regeneration and wound healing of the skin.
Collapse
Affiliation(s)
- Ernesto Bockamp
- Johannes Gutenberg-Universität Mainz, Institute of Toxicology/Mouse Genetics, Obere Zahlbacher Str. 67,55131, Mainz, Germany
| | - Rolf Sprengel
- Max Planck Institute for Medical Research, D-69120 Heidelber, Germany
| | - Leonid Eshkind
- Johannes Gutenberg-Universität Mainz, Institute of Toxicology/Mouse Genetics, Obere Zahlbacher Str. 67,55131, Mainz, Germany
| | - Thomas Lehmann
- TRM-Leipzig, Philipp-Rosenthal-Strasse 55, University of Leipzig, 04103 Leipzig, Germany
| | - Jan M Braun
- University of Leipzig, Institute of Clinical Immunology and Transfusion Medicine (IKIT), Germany
| | - Frank Emmrich
- University of Leipzig, Institute of Clinical Immunology and Transfusion Medicine (IKIT), Germany
| | - Jan G Hengstler
- Dortmund University of Technology, Leibniz Research Centre for Working Environment and Human Factors (IfADo), Institute of Legal Medicine and Rudolf-Boehm Institute of Pharmacology and Toxicology, University of Leipzig, Ardeystrasse 67, 44139 Dortmund, Germany
| |
Collapse
|
136
|
Jullien N, Goddard I, Selmi-Ruby S, Fina JL, Cremer H, Herman JP. Conditional transgenesis using Dimerizable Cre (DiCre). PLoS One 2007; 2:e1355. [PMID: 18159238 PMCID: PMC2131782 DOI: 10.1371/journal.pone.0001355] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2007] [Accepted: 11/27/2007] [Indexed: 11/18/2022] Open
Abstract
Cre recombinase is extensively used to engineer the genome of experimental animals. However, its usefulness is still limited by the lack of an efficient temporal control over its activity. We have recently developed a conceptually new approach to regulate Cre recombinase, that we have called Dimerizable Cre or DiCre. It is based on splitting Cre into two inactive moieties and fusing them to FKBP12 (FK506-binding protein) and FRB (binding domain of the FKBP12-rapamycin associated protein), respectively. These latter can be efficiently hetero-dimerized by rapamycin, leading to the reinstatement of Cre activity. We have been able to show, using in vitro approaches, that this ligand-induced dimerization is an efficient way to regulate Cre activity, and presents a low background activity together with a high efficiency of recombination following dimerization. To test the in vivo performance of this system, we have, in the present work, knocked-in DiCre into the Rosa26 locus of mice. To evaluate the performance of the DiCre system, mice have been mated with indicator mice (Z/EG or R26R) and Cre-induced recombination was examined following activation of DiCre by rapamycin during embryonic development or after birth of progenies. No recombination could be observed in the absence of treatment of the animals, indicating a lack of background activity of DiCre in the absence of rapamycin. Postnatal rapamycin treatment (one to five daily injection, 10 mg/kg i.p) induced recombination in a number of different tissues of progenies such as liver, heart, kidney, muscle, etc. On the other hand, recombination was at a very low level following in utero treatment of DiCrexR26R mice. In conclusion, DiCre has indeed the potentiality to be used to establish conditional Cre-deleter mice. An added advantage of this system is that, contrary to other modulatable Cre systems, it offers the possibility of obtaining regulated recombination in a combinatorial manner, i.e. induce recombination at any desired time-point specifically in cells characterized by the simultaneous expression of two different promoters.
Collapse
Affiliation(s)
- Nicolas Jullien
- ICNE-UMR 6544 Centre National de la Recherche Scientifique (CNRS), Université de la Méditerranée, Marseille, France
| | - Isabelle Goddard
- Centre de Transgenèse, Faculté de Médecine Nord, Institut Fédératif de Recherche (IFR) Jean-Roche, Marseille, France
| | - Samia Selmi-Ruby
- INSERM UMR 664, Faculté de Médecine RTH Laennec, Université Lyon I, Lyon, France
| | - Jean-Luc Fina
- Centre de Transgenèse, Faculté de Médecine Nord, Institut Fédératif de Recherche (IFR) Jean-Roche, Marseille, France
| | - Harold Cremer
- IBDML-UMR 6216 Centre National de la Recherche Scientifique (CNRS), Université de la Méditerranée, Marseille, France
| | - Jean-Paul Herman
- ICNE-UMR 6544 Centre National de la Recherche Scientifique (CNRS), Université de la Méditerranée, Marseille, France
- * To whom correspondence should be addressed. E-mail:
| |
Collapse
|
137
|
Varshavsky A. Targeting the absence: homozygous DNA deletions as immutable signposts for cancer therapy. Proc Natl Acad Sci U S A 2007; 104:14935-40. [PMID: 17846424 PMCID: PMC1986591 DOI: 10.1073/pnas.0706546104] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2007] [Indexed: 02/01/2023] Open
Abstract
Many cancers harbor homozygous DNA deletions (HDs). In contrast to other attributes of cancer cells, their HDs are immutable features that cannot change during tumor progression or therapy. I describe an approach, termed deletion-specific targeting (DST), that employs HDs (not their effects on RNA/protein circuits, but deletions themselves) as the targets of cancer therapy. The DST strategy brings together both existing and new methodologies, including the ubiquitin fusion technique, the split-ubiquitin assay, zinc-finger DNA-recognizing proteins and split restriction nucleases. The DST strategy also employs a feedback mechanism that receives input from a circuit operating as a Boolean OR gate and involves the activation of split nucleases, which destroy DST vector in normal (nontarget) cells. The logic of DST makes possible an incremental and essentially unlimited increase in the selectivity of therapy. If DST strategy can be implemented in a clinical setting, it may prove to be curative and substantially free of side effects.
Collapse
Affiliation(s)
- Alexander Varshavsky
- Division of Biology, California Institute of Technology, Pasadena, CA 91125, USA.
| |
Collapse
|
138
|
Abstract
Animal models of cancer provide an alternative means to determine the causes of and treatments for malignancy, thus representing a resource of immense potential for cancer medicine. The sophistication of modelling cancer in mice has increased to the extent that investigators can both observe and manipulate a complex disease process in a manner impossible to perform in patients. However, owing to limitations in model design and technology development, and the surprising underuse of existing models, only now are we realising the full potential of mouse models of cancer and what new approaches are needed to derive the maximum value for cancer patients from this investment.
Collapse
|
139
|
Ernst E, Schönig K, Bugert JJ, Bläker H, Pfaff E, Stremmel W, Encke J. Generation of inducible hepatitis C virus transgenic mouse lines. J Med Virol 2007; 79:1103-12. [PMID: 17596832 DOI: 10.1002/jmv.20911] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Hepatitis C virus (HCV) is the causative agent of most cases of chronic liver disease, cirrhosis, and hepatocellular carcinoma (HCC) affecting more than 170 million people world-wide. Progress in elucidating the nature of HCV and the development of new therapeutic strategies is hampered fundamentally by the absence of adequate small animal models simulating natural HCV infection. The creation of conditional mouse lines with the tetracycline-controlled gene expression system holds new perspectives for simulation of wild-type HCV infection in a small animal model. Transgenic mice were established with tetracycline-inducible coexpression of HCV core or HCV open reading frame (ORF) and luciferase. In long-term induction experiments, mice were examined for immunopathological changes after expression of HCV proteins. Inducible and liver-specific expression of transgenes was detected by Western blot, immunoprecipitation, luciferase assay and in vivo imaging of bioluminescence of luciferase in genetically modified mice. Ectopic expression levels were determined quantitatively in the liver, kidney, heart and spleen of mice in the induced and non-induced state. During long-term induction an elevation of aminotransaminases (ALT) was observed only in HCV core/ORF-expressing mice, but HCV-specific immune response was not confirmed by in vitro immunological assays. The histology of liver sections provided evidence of steatosis, which was correlated with an inflammatory response. The inducible HCV-transgenic mouse lines provide further evidence of liver pathogenesis in the presence of inflammation during liver-specific expression of HCV proteins and offer new insights into the effects of temporally and spatially controlled protein expression of HCV.
Collapse
Affiliation(s)
- Evelyn Ernst
- Internal Medicine IV, University of Heidelberg, Heidelberg, Germany
| | | | | | | | | | | | | |
Collapse
|
140
|
Oberto A, Acquadro E, Bus T, Sprengel R, Eva C. Expression patterns of promoters for NPY Y1 and Y5 receptors in Y5RitTA and Y1RVenus BAC-transgenic mice. Eur J Neurosci 2007; 26:155-70. [PMID: 17614946 DOI: 10.1111/j.1460-9568.2007.05631.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
In the rat brain, neuropeptide Y (NPY) Y(1) and Y(5) receptors are coexpressed in various forebrain regions where they mediate several NPY-activated functions, including feeding behaviour, anxiety, neuronal excitability and hormone secretion. We studied the distribution pattern and cellular colocalization of the Y(1) and the Y(5) receptor gene expression in the mouse brain by using transgenic mice with genomically integrated BAC clones, where the coding regions of the Y(1) and Y(5) receptor genes were replaced by Venus and the synthetic transcription factor itTA reporter genes, respectively (Tg(Y5RitTA/Y1RVenus) mice). Analysis of Venus fluorescence and itTA-mediated activation of Cre recombinase revealed copy number-dependent expression levels, between the lines, but similar expression patterns. In three transgenic lines the BAC encoded Y(5) receptor promoter induced strong Cre expression in the olfactory system, cerebral cortex, hippocampus and basal ganglia. Weaker expression was found in most of the hypothalamic nuclei of line 25, the highest-expressing transgenic line. Activation of Cre was itTA-dependent and could be regulated by doxycycline. The Y(1) receptor promoter-induced Venus fluorescence was intense, widely present through the brain and colocalized with Cre immunostaining in neurons of distinct brain regions, including the cerebral cortex, basolateral amygdala, dentate gyrus and paraventricular nucleus. These data provide a detailed and comparative mapping of Y(1) and Y(5) receptor promoter activity within cells of the mouse brain. The Tg(Y5RitTA/Y1RVenus)-transgenic mice generated here also represent a genetic tool for conditional mutagenesis via the Cre lox system, particularly of genes involved in feeding behaviour, neuronal excitability and hormone secretion.
Collapse
Affiliation(s)
- Alessandra Oberto
- Dipartimento di Anatomia, Farmacologia e Medicina Legale, Sezione di Farmacologia, Via Pietro Giuria 13, 10125 Torino, Italy
| | | | | | | | | |
Collapse
|
141
|
Abstract
Conditional gene knockouts are a very powerful tool for elucidating gene function in animal physiology and behavior. To obtain cell-specific knockouts, a promoter is utilized that drives expression of Cre recombinase specifically to the cell population of interest. We describe several transgenic lines of mice that were created in an attempt to obtain astrocyte-specific gene recombination. A 2 kb fragment from the human glial fibrillary acidic protein promoter is utilized to drive expression of inducible Cre recombinase, with both the Tet-Off and tamoxifen responsive systems. We show data obtained from crosses with two Cre reporter lines, ROSA26R and an astrocyte Cre reporter created in our laboratory, to assess the cell specificity of gene recombination. Additionally, our system is shown to successfully recombine a floxed Connexin43 locus, although recombination is not as extensive as seen in crosses with reporter lines.
Collapse
Affiliation(s)
- Kristen B Casper
- Department of Pharmacology, University of North Carolina, Chapel Hill, North Carolina 27599, USA
| | | | | |
Collapse
|
142
|
Affiliation(s)
- Susan M Dymecki
- Department of Genetics, Harvard Medical School, 77 Avenue Louis Pasteur, Boston, MA 02115, USA.
| | | |
Collapse
|
143
|
Niewoehner B, Single FN, Hvalby Ø, Jensen V, Meyer zum Alten Borgloh S, Seeburg PH, Rawlins JNP, Sprengel R, Bannerman DM. Impaired spatial working memory but spared spatial reference memory following functional loss of NMDA receptors in the dentate gyrus. Eur J Neurosci 2007; 25:837-46. [PMID: 17313573 PMCID: PMC2777262 DOI: 10.1111/j.1460-9568.2007.05312.x] [Citation(s) in RCA: 171] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Novel spatially restricted genetic manipulations can be used to assess contributions made by synaptic plasticity to learning and memory, not just selectively within the hippocampus, but even within specific hippocampal subfields. Here we generated genetically modified mice (NR1ΔDG mice) exhibiting complete loss of the NR1 subunit of the N-methyl-d-aspartate receptor specifically in the granule cells of the dentate gyrus. There was no evidence of any reduction in NR1 subunit levels in any of the other hippocampal subfields, or elsewhere in the brain. NR1ΔDG mice displayed severely impaired long-term potentiation (LTP) in both medial and lateral perforant path inputs to the dentate gyrus, whereas LTP was unchanged in CA3-to-CA1 cell synapses in hippocampal slices. Behavioural assessment of NR1ΔDG mice revealed a spatial working memory impairment on a three-from-six radial arm maze task despite normal hippocampus-dependent spatial reference memory acquisition and performance of the same task. This behavioural phenotype resembles that of NR1ΔCA3 mice but differs from that of NR1ΔCA1 mice which do show a spatial reference memory deficit, consistent with the idea of subfield-specific contributions to hippocampal information processing. Furthermore, this pattern of selective functional loss and sparing is the same as previously observed with the global GluR-A l-α-amino-3-hydroxy-5-methyl-4-isoxazelopropionate receptor subunit knockout, a mutation which blocks the expression of hippocampal LTP. The present results show that dissociations between spatial working memory and spatial reference memory can be induced by disrupting synaptic plasticity specifically and exclusively within the dentate gyrus subfield of the hippocampal formation.
Collapse
Affiliation(s)
- B Niewoehner
- Department of Experimental Psychology, University of Oxford, South Parks Road, Oxford OX1 3UD, UK
| | | | | | | | | | | | | | | | | |
Collapse
|
144
|
Sun Y, Chen X, Xiao D. Tetracycline-inducible expression systems: new strategies and practices in the transgenic mouse modeling. Acta Biochim Biophys Sin (Shanghai) 2007; 39:235-46. [PMID: 17417678 DOI: 10.1111/j.1745-7270.2007.00258.x] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022] Open
Abstract
To accurately analyze the function of transgene(s) of interest in transgenic mice, and to generate credible transgenic animal models for multifarious human diseases to precisely mimic human disease states, it is critical to tightly regulate gene expression in the animals in a conditional manner. The ability to turn gene expression on or off in the restricted cells or tissues at specific time permits unprecedented flexibility in dissecting gene functions in health and disease. Pioneering studies in conditional transgene expression have brought about the development of a wide variety of controlled gene expression systems, which meet this criterion. Among them, the tetracycline-controlled expression systems (e.g. Tet-off system and Tet-on system) have been used extensively in vitro and in vivo. In recent years, some strategies derived from tetracycline-inducible system alone, as well as the combined use of Tet-based systems and Cre/lox P switching gene expression system, have been newly developed to allow more flexibility for exploring gene functions in health and disease, and produce credible transgenic animal models for various human diseases. In this review these newly developed strategies are discussed.
Collapse
Affiliation(s)
- Yan Sun
- Center of Experimental Animals, Sun Yat-Sen University, Guangzhou 510080, China
| | | | | |
Collapse
|
145
|
Abstract
The ability to generate genetically manipulated mice has revolutionized the study of development, cell biology, immunobiology and transplantation. Conventional gene targeting approaches lead to inactivation of the target gene in all tissues. This approach often has unintended consequences, such as embryonic lethality, which preclude studying the originally intended tissue. Newer approaches allowing conditional gene expression in a tissue-specific or temporally controlled fashion have the advantage of normal development with gene deletion only in the desired tissues. While nuances to these techniques continue to be developed, the underlying concepts remain consistent. This minireview focuses on the use of conditional gene targeting in mice using the Cre-loxP system and drug inducible gene expression using the tetracycline system.
Collapse
Affiliation(s)
- J S Maltzman
- Department of Medicine, University of Pennsylvania School of Medicine, Philadelphia, PA, USA.
| | | |
Collapse
|
146
|
Zhang J, Liu Y, Beard C, Tuveson DA, Jaenisch R, Jacks TE, Lodish HF. Expression of oncogenic K-ras from its endogenous promoter leads to a partial block of erythroid differentiation and hyperactivation of cytokine-dependent signaling pathways. Blood 2007; 109:5238-41. [PMID: 17317860 PMCID: PMC1890843 DOI: 10.1182/blood-2006-09-047050] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
When overexpressed in primary erythroid progenitors, oncogenic Ras leads to the constitutive activation of its downstream signaling pathways, severe block of terminal erythroid differentiation, and cytokine-independent growth of primary erythroid progenitors. However, whether high-level expression of oncogenic Ras is required for these phenotypes is unknown. To address this issue, we expressed oncogenic K-ras (K-ras(G12D)) from its endogenous promoter using a tetracycline-inducible system. We show that endogenous K-ras(G12D) leads to a partial block of terminal erythroid differentiation in vivo. In contrast to results obtained when oncogenic Ras was overexpressed from retroviral vectors, endogenous levels of K-ras(G12D) fail to constitutively activate but rather hyperactivate cytokine-dependent signaling pathways, including Stat5, Akt, and p44/42 MAPK, in primary erythroid progenitors. This explains previous observations that hematopoietic progenitors expressing endogenous K-ras(G12D) display hypersensitivity to cytokine stimulation in various colony assays. Our results support efforts to modulate Ras signaling for treating hematopoietic malignancies.
Collapse
Affiliation(s)
- Jing Zhang
- Whitehead Institute for Biomedical Research, Cambridge, MA, USA
| | | | | | | | | | | | | |
Collapse
|
147
|
Abstract
In the last decade, site-specific recombinases (SSRs), such as Cre and Flp, have emerged as indispensable tools for the precise in vivo manipulation of the mouse genome. It is now feasible to control, in space and time, the onset of gene knockouts in almost any tissue of the mouse, thus greatly facilitating the creation of sophisticated animal models for human disease and drug development. This review describes the basic principles and current status of the SSR technology, with a focus on strategies for conditional somatic mutagenesis using the Cre/lox system and ligand-activated Cre recombinases. Practical hints for generating and analysing conditional mouse mutants will be given and exciting novel applications of the SSR technology will be discussed, such as cell fate mapping and the combined use of Cre, Flp and other biotechnological tools. It will be shown how genetic manipulation of the mouse by site-specific recombination can provide new solutions to old problems in the analysis of human physiology and pathophysiology and how it can be employed for drug discovery and development.
Collapse
Affiliation(s)
- R Feil
- Interfakultäres Institut für Biochemie, Universität Tübingen, Hoppe-Seyler-Str. 4, 72076 Tübingen, Germany.
| |
Collapse
|
148
|
Baumgärtel K, Fernández C, Johansson T, Mansuy IM. Conditional transgenesis and recombination to study the molecular mechanisms of brain plasticity and memory. Handb Exp Pharmacol 2007:315-45. [PMID: 17203661 DOI: 10.1007/978-3-540-35109-2_13] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
In the postgenomic era, a primary focus of mouse genetics is to elucidate the role of individual genes in vivo. However, in the nervous system, studying the contribution of specific genes to brain functions is difficult because the brain is a highly complex organ with multiple neuroanatomical structures, orchestrating virtually every function in the body. Further, higher-order brain functions such as learning and memory simultaneously recruit several signaling cascades in different subcellular compartments and have highly fine-tuned spatial and temporal components. Conditional transgenic and gene targeting methodologies, however, now offer valuable tools with improved spatial and temporal resolution for appropriate studies of these functions. This chapter provides an overview of these tools and describes how they have helped gain better understanding of the role of candidate genes such as the NMDA receptor, the protein kinase CaMKIIIalpha, the protein phosphatases calcineurin and PP1, or the transcription factor CREB, in the processes of learning and memory. This review illustrates the broad and innovative applicability of these methodologies to the study of brain plasticity and cognitive functions.
Collapse
Affiliation(s)
- K Baumgärtel
- Department of Biology, Swiss Federal Institute of Technology, Medical Faculty, University Zürich, Winterthurerstrasse 190, 8057 Zürich, Switzerland
| | | | | | | |
Collapse
|
149
|
Abstract
Explorations into the molecular embryology of the mouse have played a vital role in our understanding of the basic mechanisms of gene regulation that govern development and disease. In the last 15 years, these mechanisms have been analyzed with vastly greater precision and clarity with the advent of systems that allow the conditional control of gene expression. Typically, this control is achieved by silencing or activating the gene of interest with site-specific DNA recombination or transcriptional transactivation. In this review, I discuss the application of these technologies to mouse development, focusing on recent innovations and experimental designs that specifically aid the study of the mouse embryo.
Collapse
Affiliation(s)
- M Lewandoski
- Laboratory of Cancer and Developmental Biology, NCI-Frederick, National Institutes of Health, Frederick, MD 21702-1201, USA.
| |
Collapse
|
150
|
Abstract
Unlike recombinase-mediated gene manipulations, tetracycline (Tet)-controlled genetic switches permit reversible control of gene expression in the mouse. Trancriptional activation can be induced by activators termed tTA (Tet-Off) or rtTA (Tet-On) in the absence and presence of Tet, respectively. The Tet-Off and Tet-On systems are complementary, and the decision to choose one over the other depends on the particular experimental strategy. Both systems were optimized over the years and can now be used to develop mouse models.
Collapse
Affiliation(s)
- R Sprengel
- Max Planck Institute for Medical Research, Jahnstrasse 29, 69120 Heidelberg, Germany
| | | |
Collapse
|