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Cre/loxP System (cre/loxp + system)
Selected AbstractsThe essential haematopoietic transcription factor Scl is also critical for neuronal developmentEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 7 2006Cara K. Bradley Abstract The basic helix-loop-helix (bHLH) transcription factor Scl displays tissue-restricted expression and is critical for the establishment of the haematopoietic system; loss of Scl results in embryonic death due to absolute anaemia. Scl is also expressed in neurons of the mouse diencephalon, mesencephalon and metencephalon; however, its requirement in those sites remains to be determined. Here we report conditional deletion of Scl in neuronal precursor cells using the Cre/LoxP system. Neuronal-Scl deleted mice died prematurely, were growth retarded and exhibited an altered motor phenotype characterized by hyperactivity and circling. Moreover, ablation of Scl in the nervous system affected brain morphology with abnormal neuronal development in brain regions known to express Scl under normal circumstances; there was an almost complete absence of Scl-null neurons in the hindbrain and partial loss of Scl-null neurons in the thalamus and midbrain from early neurogenesis onwards. Our results demonstrate a crucial role for Scl in the development of Scl-expressing neurons, including ,-aminobutyric acid (GABA)ergic interneurons. Our study represents one of the first demonstrations of functional overlap of a single bHLH protein that regulates neural and haematopoietic cell development. This finding underlines Scl's critical function in cell fate determination of mesodermal as well as neuroectodermal tissues. [source] Methods in Nutrition Science: Cre/loxP System for Generating Tissue-specific Knockout Mouse ModelsNUTRITION REVIEWS, Issue 6 2004Claudine H. Kos Ph.D. Editor's note: From time to time, we take the opportunity in Nutrition Reviews to highlight a particularly exciting application of sophisticated methodological advances that are relevant to the nutrition research community. In the current issue of Nutrition Reviews, Dr. Claudine Kos has provide a brief review of some of the salient features of the Cre/loxP system for generating tissue-specific knockout mouse models. Hopefully, this review will provide additional background to Dr. George Wolf's Brief Critical Review (page 253) of the use of the Cre/loxP technique by investigators to gain further insight into the function of the peroxysome proliferators-activated receptor-gamma (PPAR-,), as well as promote its further use within experimental nutrition. Alteration of the mouse genome by conventional transgenic and gene-targeted approaches has greatly facilitated studies of gene function. However, a gene alteration expressed in the germ line may cause an embryonic lethal phenotype resulting in no viable mouse to study gene function. Similarly, a gene alteration may exert its effect in multiple different cell and tissue types, creating a complex phenotype in which it is difficult to distinguish direct function in a particular tissue from secondary effects resulting from altered gene function in other tissues. Therefore, methods have been developed to control conditions such as the timing, cell-type, and tissue specificity of gene activation or repression. This brief review provides an overview of the Cre/LoxP system for generating tissue-specific knockout mouse models. [source] Transgenic mouse lines expressing Cre recombinase specifically in posterior notochord and notochord,GENESIS: THE JOURNAL OF GENETICS AND DEVELOPMENT, Issue 12 2007Amit Kumar Abstract During development, the organizer provides instructive signals to surrounding cells as well as contributing cells to axial structures. To dissect organizer function at different developmental stages, conditional approaches such as the Cre/loxP system for conditional mutagenesis are particularly useful. Here we describe two new Cre transgenic mouse lines, Foxa2 NFP-Cre and Nodal PNC-Cre, with activity in two organizer domains, the posterior notochord (PNC) and notochord. These lines were made using defined regulatory elements from the Foxa2 and Nodal genes that direct Cre expression in overlapping domains of the PNC and notochord. Our detailed analysis of the timing and location of Foxa2 NFP-Cre and Nodal PNC-Cre activity indicates that these lines are appropriate for conditional mutagenesis of genes expressed from early somite stages onward. genesis 45:729,736, 2007. Published 2007 Wiley-Liss, Inc. [source] Generation of a germ cell-specific mouse transgenic Cre line, Vasa-Cre,GENESIS: THE JOURNAL OF GENETICS AND DEVELOPMENT, Issue 6 2007Teresa Gallardo Abstract Cell type-specific genetic modification using the Cre/loxP system is a powerful tool for genetic analysis of distinct cell lineages. Because of the exquisite specificity of Vasa expression (confined to the germ cell lineage in invertebrate and vertebrate species), we hypothesized that a Vasa promoter-driven transgenic Cre line would prove useful for the germ cell lineage-specific inactivation of genes. Here we describe a transgenic mouse line, Vasa-Cre, where Cre is efficiently and specifically expressed in germ cells. Northern analysis showed that transgene expression was confined to the gonads. Cre-mediated recombination with the Rosa26-lacZ reporter was observed beginning at ,e15, and was >95% efficient in male and female germ cells by birth. Although there was a potent maternal effect with some animals showing more widespread recombination, there was no ectopic activity in most adults. This Vasa-Cre transgenic line should thus prove useful for genetic analysis of diverse aspects of gametogenesis and as a general deletor line. genesis 45:413,417, 2007. Published 2007 Wiley-Liss, Inc. [source] Abnormal lens morphogenesis and ectopic lens formation in the absence of ,-catenin function,GENESIS: THE JOURNAL OF GENETICS AND DEVELOPMENT, Issue 4 2007Jana Kreslova Abstract ,-Catenin plays a key role in cadherin-mediated cell adhesion as well as in canonical Wnt signaling. To study the role of ,-catenin during eye development, we used conditional Cre/loxP system in mouse to inactivate ,-catenin in developing lens and retina. Inactivation of ,-catenin does not suppress lens fate, but instead results in abnormal morphogenesis of the lens. Using BAT-gal reporter mice, we show that ,-catenin-mediated Wnt signaling is notably absent from lens and neuroretina throughout eye development. The observed defect is therefore likely due to the cytoskeletal role of ,-catenin, and is accompanied by impaired epithelial cell adhesion. In contrast, inactivation of ,-catenin in the nasal ectoderm, an area with active Wnt signaling, results in formation of crystallin-positive ectopic lentoid bodies. These data suggest that, outside of the normal lens, ,-catenin functions as a coactivator of canonical Wnt signaling to suppress lens fate. genesis 45:157,168, 2007. Published 2007 Wiley-Liss, Inc. [source] Generation of a conditional allele of the mouse prostaglandin EP4 receptorGENESIS: THE JOURNAL OF GENETICS AND DEVELOPMENT, Issue 1 2004André Schneider Abstract Genetic disruption of the mouse EP4 receptor results in perinatal lethality associated with persistent patent ductus areteriosus (PDA). To circumvent this, an EP4 allele amenable to conditional deletion using the Cre/loxP system was generated. The targeting construct was comprised of a floxed exon2 in tandem with the neomycin-resistance gene in intron 2, flanked by third 3, LoxP site. Mice homozygous for the targeted allele (EP4lox+neo/lox+neo), or following its Cre -mediated deletion (EP4del/del), also die within hours of birth with PDA. In contrast, mice homozygous for a partially recombined allele, retaining exon2 but lacking neo (EP4flox/flox), are viable and show no overt phenotype. Postnatal deletion of the floxed EP4 gene is efficiently achieved in the liver and kidney in a transgenic mouse expressing the inducible Mx1Cre recombinase. The EP mouse should provide a useful reagent with which to examine the physiologic roles of the EP4 receptor. genesis 40:7,14, 2004. © 2004 Wiley-Liss, Inc. [source] Temporal control of gene recombination in astrocytes by transgenic expression of the tamoxifen-inducible DNA recombinase variant CreERT2GLIA, Issue 1 2006Petra G. Hirrlinger Abstract Inducible gene modification using the Cre/loxP system provides a valuable tool for the analysis of gene function in the active animal. GFAP-Cre transgenic mice have been developed to achieve gene recombination in astrocytes, the most abundant cells of the central nervous system, with pivotal roles during brain function and pathology. Unfortunately, these mice displayed neuronal recombination as well, since the GFAP promoter is also active in embryonic radial glia, which possess a substantial neurogenic potential. To enable the temporal control of gene deletions in astrocytes only, we generated a transgenic mouse with expression of CreERT2, a fusion protein of the DNA recombinase Cre and a mutated ligand-binding domain of the estrogen receptor, under the control of the human GFAP promoter. In offspring originating from crossbreedings of GFAP-CreERT2-transgenic mice with various Cre-sensitive reporter mice, consecutive intraperitoneal injections of tamoxifen induced genomic recombination selectively in astrocytes of almost all brain regions. In Bergmann glia, which represent the main astroglial cell population of the cerebellum, virtually all cells showed successful gene recombination. When adult mice received cortical stab wound lesions, simultaneously given tamoxifen induced substantial recombination in reactive glia adjacent to the site of injury. These transgenic GFAP-CreERT2 mice will allow the functional analysis of loxP-modified genes in astroglia of the postnatal and adult brain. © 2006 Wiley-Liss, Inc. [source] Positive Regulation of Adult Bone Formation by Osteoblast-Specific Transcription Factor Osterix,,JOURNAL OF BONE AND MINERAL RESEARCH, Issue 6 2009Wook-Young Baek Abstract Osterix (Osx) is essential for osteoblast differentiation and bone formation, because mice lacking Osx die within 1 h of birth with a complete absence of intramembranous and endochondral bone formation. Perinatal lethality caused by the disruption of the Osx gene prevents studies of the role of Osx in bones that are growing or already formed. Here, the function of Osx was examined in adult bones using the time- and site-specific Cre/loxP system. Osx was inactivated in all osteoblasts by Col1a1-Cre with the activity of Cre recombinase under the control of the 2.3-kb collagen promoter. Even though no bone defects were observed in newborn mice, Osx inactivation with 2.3-kb Col1a1-Cre exhibited osteopenia phenotypes in growing mice. BMD and bone-forming rate were decreased in lumbar vertebra, and the cortical bone of the long bones was thinner and more porous with reduced bone length. The trabecular bones were increased, but they were immature or premature. The expression of early marker genes for osteoblast differentiation such as Runx2, osteopontin, and alkaline phosphatase was markedly increased, but the late marker gene, osteocalcin, was decreased. However, no functional defects were found in osteoclasts. In summary, Osx inactivation in growing bones delayed osteoblast maturation, causing an accumulation of immature osteoblasts and reducing osteoblast function for bone formation, without apparent defects in bone resorption. These findings suggest a significant role of Osx in positively regulating osteoblast differentiation and bone formation in adult bone. [source] Methods in Nutrition Science: Cre/loxP System for Generating Tissue-specific Knockout Mouse ModelsNUTRITION REVIEWS, Issue 6 2004Claudine H. Kos Ph.D. Editor's note: From time to time, we take the opportunity in Nutrition Reviews to highlight a particularly exciting application of sophisticated methodological advances that are relevant to the nutrition research community. In the current issue of Nutrition Reviews, Dr. Claudine Kos has provide a brief review of some of the salient features of the Cre/loxP system for generating tissue-specific knockout mouse models. Hopefully, this review will provide additional background to Dr. George Wolf's Brief Critical Review (page 253) of the use of the Cre/loxP technique by investigators to gain further insight into the function of the peroxysome proliferators-activated receptor-gamma (PPAR-,), as well as promote its further use within experimental nutrition. Alteration of the mouse genome by conventional transgenic and gene-targeted approaches has greatly facilitated studies of gene function. However, a gene alteration expressed in the germ line may cause an embryonic lethal phenotype resulting in no viable mouse to study gene function. Similarly, a gene alteration may exert its effect in multiple different cell and tissue types, creating a complex phenotype in which it is difficult to distinguish direct function in a particular tissue from secondary effects resulting from altered gene function in other tissues. Therefore, methods have been developed to control conditions such as the timing, cell-type, and tissue specificity of gene activation or repression. This brief review provides an overview of the Cre/LoxP system for generating tissue-specific knockout mouse models. [source] Expression of Cre Recombinase in Pigment CellsPIGMENT CELL & MELANOMA RESEARCH, Issue 4 2002Laurence Guyonneau Conditional gene targeting using the Cre/loxP system enables specific deletion of a gene in a tissue of interest. For application of Cre-mediated recombination in pigment cells, Cre expression has to be targeted to pigment cells in transgenic mice. So far, no pigment cell-specific Cre transgenic line has been reported and we present and discuss our first results on use of Cre recombinase in pigment cells. A construct was generated where Cre recombinase is controlled by the promoter of the mouse dopachrome tautomerase (Dct) gene. The construct was functionally tested in vitro and introduced into mice. Following breeding to two reporter mouse strains, we detected Cre recombinase activity in telencephalon, melanoblasts, and retinal pigment epithelium (RPE). Our data demonstrate the feasibility of pigment cell-specific Cre/loxP-mediated recombination. [source] | |||||||||||||