Gene/Protein Disease Symptom Drug Enzyme Compound
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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)

In the testes homogenates of rats kept on a A-deficient ration and receiving additionally retinyl-acetate (control) and retinoic acid (experiment) the activity of the phospholipases A1 and A2, with 1-acyl-2(1-14C)-oleoyl-SN-glycero-3-galactosidase and acid phosphatase employed as a substrate, was investigated. In the testes of rats receiving retinyl-acetate the activity of the phospholipases A1 and A2 was greatly declining. An addition of retinyl to the testes homogenates of test rats contributed to re-establishing the activity of the phospholipases up to the control level. In the testes of rats receiving retinoic acid a reduced activity of the acid phosphatase and a rise of beta-galactosidase, as compared to their activity in controls was also demonstrable.
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PMID:[Effect of retinol deficiency on the activity of phospholipase A lysosomal enzymes in rat testes]. 88 29

A P19 embryonal carcinoma stem cell line carrying an insertion of the E. coli LacZ gene in an endogenous copy of the Pax-3 gene was identified. Expression of the Pax-3/LacZ fusion gene in neuroectodermal and mesodermal lineages following induction of differentiation by chemical treatments (retinoic acid and dimethylsulfoxide) was characterized using this line and is consistent with the previous localization of Pax-3 expression in the embryo to mitotically active cells of the dorsal neuroectoderm and the adjacent segmented dermomyotome. Pax-3/LacZ marked stem cells were also utilized as target cells in mixing experiments with unmarked P19 cells that had been differentiated by pretreatment with chemical inducers. Induction of beta-galactosidase and neuroectodermal markers in the target cells demonstrates that: (1) some differentiated P19 cell derivatives transiently express endogenous Pax-3- and neuroectoderm-inducing activities, (2) undifferentiated target stem cells respond to these activities even in the presence of leukemia inhibitory factor and (3) the endogenous activities can be distinguished from, and are more potent than, retinoic acid treatment in inducing neuroectoderm. These observations demonstrate that P19 embryonal carcinoma cells provide a useful in vitro system for analysis of the cellular interactions responsible for neuroectoderm induction in mammals.
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PMID:Expression of Pax-3- and neuroectoderm-inducing activities during differentiation of P19 embryonal carcinoma cells. 128 55

Retinoic acid (RA) receptors (RARs) are ligand-inducible transcription factors that bind to specific DNA sequences associated with the regulatory regions of RA-regulatable genes. Since RA has been implicated as an important factor both in normal development and in teratological studies, one would like to have a model system that detects the presence of activated receptors during development. We have constructed a recombinant reporter gene that has three copies of the RA response element (RARE) from the RAR beta-2 promoter 5' to the herpes simplex virus thymidine kinase promoter; this regulatory region is coupled to the bacterial beta-galactosidase reporter gene. This construct was RA inducible in transient transfection assays in F9 embryonal carcinoma cells. Transgenic embryos with this reporter gene construct exhibited restricted and reproducible patterns of beta-galactosidase activity during embryogenesis, beginning between gestational ages day 7.5 and 8.5. At day 8.5, beta-galactosidase activity was detected in the closed neurotube and somites. Day 8.5 embryos, from pregnant females fed RA 14 hr earlier, exhibited a greater intensity and distribution of beta-galactosidase activity. Similarly, at later stages of gestation, maternal RA exposure resulted in enhanced embryonic beta-galactosidase expression. This type of transgenic indicator mouse should be useful in detailing the role of activated RARs during embryonic development.
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PMID:Transgenic indicator mice for studying activated retinoic acid receptors during development. 131 86

Retinoic acid receptors (RARs) modulate gene expression following association with retinoic acid (RA). In transient transfection, an RAR alpha-beta-galactosidase fusion protein (RAR-LacZ) was able to transactivate expression in the absence of RA. When expressed in the ocular lens of transgenic mice, this constitutively active RAR-LacZ fusion gene resulted in founder and progeny animals that exhibited cataracts and microphthalmia, both being characteristics of retinoid-induced teratogenesis. The transgenic phenotypes indicate that retinoid teratogenesis can be mimicked by expression of a constitutively active RAR-LacZ fusion protein in retinoid-sensitive tissues.
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PMID:Transgenic mice expressing a constitutively active retinoic acid receptor in the lens exhibit ocular defects. 131 36

NTera 2/cl.D1 (NT2) cells, a human teratocarcinoma cell line, were manipulated following retinoic acid treatment to yield greater than 95% pure cultures of neuronal cells (NT2-N cells). The commitment of NT2-N cells to a stable neuronal phenotype is irreversible as judged by the lack of mitotic activity or phenotypic reversion over a period of 2 months in culture. Furthermore, NT2-N cells express a variety of neuronal markers including many neuronal cytoskeletal proteins, secretory markers, and surface markers. NT2-N cells resemble primary neuronal cultures from rodents morphologically and in density of process outgrowth and, like primary neurons, go on to elaborate processes that differentiate into axons and dendrites. This culture method yields sufficient highly differentiated postmitotic NT2-N cells for both biochemical and molecular biological studies. Indeed, when undifferentiated NT2 cells were stably transfected with a beta-galactosidase (beta-gal) expression plasmid, beta-gal expression was shown to be present in both undifferentiated NT2 and postmitotic NT2-N cells. Thus, the ability to transfect expression plasmids into undifferentiated NT2 cells will allow the introduction of normal and mutant gene products into cells that can then be induced to become stable, postmitotic human neurons. We conclude that NT2 cells and NT2-N cells represent a unique model system for studies of human neurons, and a novel vehicle for the expression of diverse gene products in terminally differentiated polarized neurons.
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PMID:Pure, postmitotic, polarized human neurons derived from NTera 2 cells provide a system for expressing exogenous proteins in terminally differentiated neurons. 157 71

Retinoic acid (RA) is a signalling molecule important for pattern formation during development. There are three known types of nuclear receptors for RA in mammals, RAR-alpha, RAR-beta and RAR-gamma, which transduce the RA signal by inducing or repressing the transcription of target genes. Here we describe the developmental expression pattern of the mouse RAR-beta 2 promoter. Independent lines of transgenic animals expressing RAR-beta 2 promoter sequences fused to the E. coli beta-galactosidase gene were examined throughout the course of embryogenesis and found to exhibit reproducible and specific patterns of beta-galactosidase expression in a majority of sites that have been shown previously to contain mRAR-beta transcripts. In the limbs, mRAR-beta 2 promoter activity and mRAR-beta transcripts were both excluded from precartilagenous condensations; interestingly, mRAR-beta 2 promoter activity was observed in the apical ectodermal ridge (AER) where mRAR-beta transcripts could not be detected, while no mRAR-beta 2 promoter activity or mRAR-beta transcripts were associated with the limb region that contains the zone of polarizing activity (ZPA). Analysis of the lacZ expression pattern in embryos from mothers treated with teratogenic doses of RA, indicated that mRAR-beta 2 promoter is selectively induced in a manner suggesting that overexpression of the mRAR-beta 2 isoform is involved in RA-generated malformations. The normal and induced expression pattern of the mRAR-beta 2 promoter suggests several possible roles for mRAR-beta 2 in development of the limbs, as an inhibitor of cartilage formation, in programmed cell death and in the formation of loose connective tissue.
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PMID:Developmental analysis of the retinoic acid-inducible RAR-beta 2 promoter in transgenic animals. 166 76

Evidence from expression studies using transfected F9 teratocarcinoma stem cells indicates that the synthesis of the H1(0) histone is turned on very soon after the cells have been treated with retinoic acid, which causes them to differentiate into murine parietal endoderm. This increase in H1(0) at the time of commitment would allow a reorganization of the chromatin with a reprogramming of the gene activity of undifferentiated F9 cells to the differentiated state. The particular interest of the further development of this differentiation model is to answer the question whether this specific stimulation of expression can be induced only in homologous differentiation systems, or whether the identified H1(0) promoter sequences can also be specifically stimulated by heterologous factors. We therefore injected the mammalian H1(0) promoter sequences into Xenopus oocytes and fertilized eggs. The results of oocyte injection experiments indicate that H1(0) promoter sequence elements similar to those used in transfected F9 cells are specifically expressed in the oocyte. For analysis of H1(0) expression in Xenopus embryos we used promoter constructs ligated to beta-galactosidase sequences for microinjection. This procedure allows a particularly rapid and complete detection of expressed promoter clones within the differentiated tissues of the early Xenopus embryo.
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PMID:Expression of mouse histone H1(0) promoter sequences following microinjection into Xenopus oocytes and developing embryos. 251 51

Expression vectors have been constructed for a region of the human retinoic acid receptor-alpha (hRAR-alpha) and transferred into F9 embryonal carcinoma (EC) cells. When the vectors are overexpressed in F9 cells, clones can be selected for resistance to retinoic acid-induced differentiation. This effect is obtained even when the hRAR-alpha region is expressed as a beta-galactosidase fusion protein. Using the beta-galactosidase component of the fusion protein as a marker, overexpression of the fusion protein has been correlated with the retinoic acid-resistance effect. The clones resistant to retinoic acid no longer exhibit the normal retinoic acid induction of endo B cytokeratin, laminin B-1, and tissue plasminogen activator mRNAs observed with normal F9 cells. Retinoic acid induction of type IV alpha-1 collagen and Hox-1.3 RNAs is observed with these clones. When transfected with a thyroid receptor DNA-binding sequence (TRE)/thymidine kinase promoter/luciferase construct, the retinoic acid-resistant clones do not yield the same retinoic acid-induced level of luciferase obtained with F9 cells. It is hypothesized that the RAR vectors are interfering with endogenous RAR(s) in a dominant-negative manner to inhibit retinoic acid-induced differentiation of F9 EC cells.
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PMID:Retinoic acid receptor expression vector inhibits differentiation of F9 embryonal carcinoma cells. 255 44

We have investigated the role of 5'-flanking DNA sequences in regulating the expression of the murine Sparc (osteonectin) gene in parietal endoderm cells and in F9 embryonal carcinoma cells induced to differentiate into parietal endoderm with retinoic acid and cyclic AMP. Varying lengths of flanking sequences extending up to 3.0 kilobase pairs 5' of the transcription initiation site were linked to the bacterial chloramphenicol transacetylase gene in the Bluescript M13- vector. The constructs were tested in transient assays, using a beta-galactosidase plasmid as a transfection control. Sequences between 78 and 169 base pairs upstream of the cap site are the minimum required for cell-type specific promoter activity; this region is dominated by two oligopurine/oligopyrimidine stretches or "GAGA" boxes and is highly conserved between the mouse and bovine genes. Addition of the sequence between -169 and -449, which includes part or all of a third GAGA box, results in increased parietal endoderm specific transcription, up to a maximum of 6.3-fold higher than in undifferentiated F9 cells. Further addition of sequences between -449 and -638 markedly reduces promoter activity in both cell types but parietal endoderm-specific activity is restored in constructs containing 2.2 and 3.0 kilobase pairs of flanking DNA. In addition, we have identified sequences related to the consensus sequence for steroid response elements, one of which is able to confer progesterone-enhanced transcription when tested with a heterologous promoter in steroid responsive cells. These results suggest that negative and positive elements normally interact to regulate the temporal and tissue-specific patterns of Sparc gene transcription seen in vivo.
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PMID:Evidence for positive and negative regulatory elements in the 5'-flanking sequence of the mouse sparc (osteonectin) gene. 274 36

T3 receptors (TRs) regulate transcription by binding to specific DNA response elements as heterodimers with the retinoid X receptors (RXRs). To study the consequences of this heterodimerization for transcriptional regulation in the absence of complications associated with its effects on DNA binding affinity, we expressed in the yeast Saccharomyces cerevisiae a chimeric protein consisting of the rat TR beta 1 ligand-binding domain fused to the DNA-binding domain of the bacterial repressor lexA (lexATR). LexATR is a weak, T3-responsive activator of a beta-galactosidase reporter gene controlled by upstream lexA-binding sites (lexA-beta-gal). In contrast, coexpression of human RXR alpha (hRXR alpha) strongly enhances both the basal and ligand-induced transcriptional activities. Both the N-terminal activation domain of RXR and sequences at the extreme C terminus of lexATR are required for this T3- and RXR-dependent transcriptional activation. The lexATR chimera was also used to characterize receptor-receptor interactions using the two-hybrid system. Coexpression of B42RXR, a fusion protein of the human RXR alpha ligand-binding domain and the B42 transcriptional activation domain, strongly increases the transcriptional activity of lexATR in the absence of T3 or 9-cis-retinoic acid. We conclude that RXR is essential for full, T3-dependent transcriptional activity of the TR in yeast, and that protein-protein interaction of TR and RXR in vivo is ligand-independent.
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PMID:A chimeric thyroid hormone receptor constitutively bound to DNA requires retinoid X receptor for hormone-dependent transcriptional activation in yeast. 783 57


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