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Query: EC:3.2.1.23 (beta-galactosidase)
 14,648 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The cerebellar cortex and its sole output, the Purkinje cell, have been implicated in motor coordination, learning and cognitive functions. Therefore, the ability to generate Purkinje cell-specific mutations in physiologically relevant genes is of particular neurobiological interest. A suitable approach is the Cre/loxP strategy that allows temporally and spatially controlled gene inactivation. Here, we present the characterization of transgenic mouse strains expressing Cre recombinase controlled by the L7/pcp-2 gene. Endogenous L7/pcp-2 protein is expressed exclusively in Purkinje cells and retinal bipolar neurones. Recombination was detected by beta-galactosidase histochemistry in tissues from crosses of the L7/pcp-2:Cre transgenic lines with two different indicator strains, GtROSA26 and ACZL. Purkinje cells in all folia of the cerebellum displayed intense beta-galactosidase staining, whereas only few blue cells were observed in the retina and other parts of the CNS. Thus, these transgenic lines are potentially of great importance for genetic manipulations in cerebellar Purkinje cells.
Genesis
PMID:Cre recombinase expression in cerebellar Purkinje cells. 1110 49

This study describes an in utero approach for overexpressing genes in a cell-type directed manner. It uses an avian leukosis retroviral expression system coupled with a transgenic mouse line expressing the viral receptor tv-a from a tissue-specific promoter (RCAS-TVA system) (Federspiel et al., 1994, and reviewed in Fisher et al., 1999). A transgenic mouse line was generated expressing tv-a from the Dopachrome tautomerase promoter (DCT-tv-a) in embryonic melanocyte precursors (melanoblasts). RCAS virus encoding beta-galactosidase (RCAS-LacZ) or tyrosinase (RCAS-Tyr) was injected in utero into embryonic day 12.5 albino (tyrosinase inactive) mouse embryos. Animals were analyzed for beta-galactosidase activity or tyrosinase activity (hair pigmentation). RCAS gene expression was detected in 44% and 25% of the transgenic mice, respectively. We demonstrate the RCAS-TVA system coupled with the DCT-tv-a line of mice can be used for in utero infection.
Genesis 2001 Jun
PMID:In utero complementation of a neural crest-derived melanocyte defect using cell directed gene transfer. 1141 66

Despite the overall successful application of the tet-system to regulate gene expression in vitro and in vivo, nothing is known so far about the long-term stability of this system in transgenic mice. In this study, mice of generation F2, F3, F4, or F10 of two independent tTA(CMV) transgenic lines were bred with NZL-2 mice containing a tTA-responsive bidirectional promoter that allows the simultaneous expression of two reporter genes encoding luciferase and beta-galactosidase. Analysis of the expression of transgenes in double transgenic mice revealed a dramatic reduction of tTA transactivator mRNA over time. As a consequence, the expression of both reporter genes was gradually reduced from generation to generation in tissues of embryonic and adult NZL-2/tTA(CMV) mice. Luciferase activity in NZL-2/tTA(CMV)(F10) mice was reduced 8-10-fold compared to NZL-2/ tTA(CMV)(F2) mice, and beta-galactosidase expression was no longer detectable. In summary, we describe the long-term instability of the tet-system in our NZL-2/tTA(CMV) double transgenic mice. The molecular basis of this observation and experimental tools to overcome this limitation need to be addressed in future.
Genesis 2001 Oct
PMID:Generation dependent reduction of tTA expression in double transgenic NZL-2/tTA(CMV) mice. 1166 82

Nkx2-5, one of the earliest cardiac-specific markers in vertebrate embryos, was used as a genetic locus to knock in the Cre recombinase gene by homologous recombination. Offspring resulting from heterozygous Nkx2-5/Cre mice mated to ROSA26 (R26R) reporter mice provided a model system for following Nkx2-5 gene activity by beta-galactosidase (beta-gal) activity. beta-gal activity was initially observed in the early cardiac crescent, cardiomyocytes of the looping heart tube, and in the epithelium of the first pharyngeal arch. In later stage embryos (10.5-13.5 days postcoitum, dpc), beta-gal activity was observed in the stomach and spleen, the dorsum of the tongue, and in the condensing primordium of the tooth. The Nkx2-5/Cre mouse model should provide a useful genetic resource to elucidate the role of loxP manipulated genetic targets in cardiogenesis and other developmental processes.
Genesis 2001 Dec
PMID:Embryonic expression of an Nkx2-5/Cre gene using ROSA26 reporter mice. 1178 8

Cre transgenic mice can be used to delete gene sequences flanked by loxP sites in specific somatic tissues. We have generated vavCre transgenic mice, which can be used to inactivate genes specifically in adult hematopoietic and endothelial cells. In these animals, a Cre transgene is expressed under control of murine vav gene regulatory elements. To assess their usefulness, vavCre transgenic mice were bred with R26R mice, which express a lacZ reporter gene only in cells where Cre-mediated recombination has occurred. VavCre/R26R double-heterozygous offspring were analyzed by beta-galactosidase histochemistry and flow cytometry. VavCre-mediated recombination occurred in most hematopoietic cells of all hematopoietic organs, including the hematopoietic progenitor-rich bone marrow. Recombination also occurred in most endothelial and germ cells, but only rarely in other cell types. The recombination in both hematopoietic and endothelial lineages may partly reflect their putative shared ontogeny and provides a unique tool for simultaneous pan-hematopoietic and endothelial mutagenesis.
Genesis 2002 Dec
PMID:VavCre transgenic mice: a tool for mutagenesis in hematopoietic and endothelial lineages. 1243 35

We report a transgenic mouse line that expresses Cre recombinase exclusively in podocytes. Twenty- four transgenic founders were generated in which Cre recombinase was placed under the regulation of a 2.5-kb fragment of the human NPHS2 promoter. Previously, this fragment was shown to drive beta-galactosidase (beta-gal) expression exclusively in podocytes of transgenic mice. For analysis, founder mice were bred with ROSA26 mice, a reporter line that expresses beta-gal in cells that undergo Cre recombination. Eight of 24 founder lines were found to express beta-gal exclusively in the kidney. Histological analysis of the kidneys showed that beta-gal expression was confined to podocytes. Cre recombination occurred during the capillary loop stage in glomerular development. No evidence for Cre recombination was detected in any of 14 other tissues examined.
Genesis 2003 Jan
PMID:Podocyte-specific expression of cre recombinase in transgenic mice. 1248 Dec 97

Embryonic or neonatal lethality of mice with targeted disruption of critical genes preclude them from further characterization of specific roles of these genes during postnatal development and aging. In order to study the molecular roles of such genes in teeth, we generated transgenic mouse lines expressing bacteriophage Cre recombinase under the control of the mouse dentin sialophosphoprotein (dspp) gene promoter. The expression of Cre recombinase protein was mainly detected in the nucleus of the odontoblasts. The efficiency of Cre activity was analyzed by crossing the Dspp-Cre mice with ROSA26 reporter (R26R) mice. The offspring with both genotypes have shown specific deletion of intervening sequences flanked by loxP sites upstream of the reporter gene, thereby facilitating the expression of the beta-galactosidase (beta-gal) gene in the teeth. The activity of beta-gal was initially observed in the odontoblasts of 1-day-old mice and increased with tooth development. Almost all of the odontoblasts have shown lacZ activity by 3 weeks of age. We could not detect Cre recombinase activity in any other cells, including ameloblasts. These studies indicate that the Dspp-Cre transgenic mice will be valuable to generate odontoblast-specific gene knockout mice so as to gain insight into the molecular roles of critical genes in the odontoblasts during dentinogenesis.
Genesis 2003 Feb
PMID:Odontoblast-specific expression of cre recombinase successfully deletes gene segments flanked by loxP sites in mouse teeth. 1253 91

Laminins exert numerous effects on neurons in vitro, but expression of laminin subunit genes by neurons in vivo remains controversial. To reexamine this issue, we generated mice from ES cells in which the laminin alpha1, alpha5, beta1, and gamma1 genes had been "trapped" by insertion of a histochemically detectable selectable marker, betageo (beta-galactosidase fused to neomycin phosphotransferase). The presence of laminin-betageo fusion proteins was assayed histochemically and immunochemically, revealing expression of laminin beta1 and gamma1 genes, but not alpha chain genes, by defined subsets of neurons in brain and retina. We also used the gene traps in a novel way to assay expression of endogenous laminin subunits, which were barely detectable by ordinary immunohistochemical methods. The trapping vector included a transmembrane domain that anchors proteins otherwise destined for secretion. Laminin alpha/beta/gamma heterotrimers are assembled intracellularly, and we show that the trapped laminin gamma1 fusion protein "co-trapped" endogenous beta1 intracellularly. The laminin gamma1 fusion was also able to co-trap transgene-derived alpha chains, but we detected no co-trapped endogenous alpha chains. The co-trapping method may be generally useful for identifying proteins or isolating protein complexes associated with trapped gene products.
Genesis 2003 Jun
PMID:Expression of laminin chains by central neurons: analysis with gene and protein trapping techniques. 1282 Jan 73

The Cre-loxP system is increasingly exploited for spatial and temporal gene inactivation. Here we present a novel approach to achieve this goal of selective gene inactivation. Following the model of alpha complementation in the beta-galactosidase enzyme, where the enzyme is split into independent polypeptides which are able to associate and maintain the enzymatic activity, we divided the Cre recombinase into two independent polypeptides (one containing the NH(2) terminus (alpha) and a second one containing the COOH-terminus (beta)). Individually, the two polypeptides have no detectable activity. However, when coexpressed the polypeptides are able to associate, giving rise to Cre enzymatic activity, which optimally is as high as 30% of that seen with wildtype Cre recombinase in vitro. We present this strategy as a modification of the traditional Cre-loxP system, which could be used to obtain a highly specific recombination pattern by expressing the two halves under the control of separate promoters.
Genesis 2003 Sep
PMID:Alpha complementation in the Cre recombinase enzyme. 1450 74

Dlx5 and Dlx6, two members of the Distalless gene family, are required for development of numerous tissues during embryogenesis, including facial and limb development. This gene pair is expressed in tandem, transcribed toward each other and separated by a short intergenic region containing multiple putative enhancers. Targeted inactivation of Dlx5 and Dlx6 in mice results in multiple developmental defects in craniofacial and limb structures, suggesting that these genes are crucial for aspects of both neural crest and nonneural crest development. To further investigate potential developmental roles of Dlx5 and Dlx6, we used one of the Dlx5/6 intergenic enhancers to drive Cre recombinase expression in transgenic mice. Crossing Dlx5/6-Cre transgenic mice with mice from the R26R strain results in beta-galactosidase staining in the apical ectodermal ridge, brain, and neural crest-derived mesenchyme of the pharyngeal arches, with staining in term embryos observed in the facial skeleton and specific brain structures. However, in contrast to endogenous expression patterns of Dlx5 and Dlx6, Cre expression within the pharyngeal arches occurs during a very narrow window in early development. Our studies suggest that Dlx5/6-Cre mice may prove useful both in further understanding the function and regulation of Distalless genes during development and in studies of gene function in conditional knockout mice.
Genesis 2003 Dec
PMID:Dlx5/6-enhancer directed expression of Cre recombinase in the pharyngeal arches and brain. 1466 12


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