Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: 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)

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

The first gene of the Bacillus subtilis RNA polymerase sigma 43 operon, P23, has a protein-coding capacity of 23,000 daltons. Sequence analysis revealed three potential translational initiation sites within the same reading frame, which could encode proteins of 23,000 (P23), 19,000 (P19), and 9,000 (P9) daltons, respectively. An internal promoter (P3), which is expressed only during the sporulation stage, is located between the second and the third translational start sites. By protein fusion to the Escherichia coli beta-galactosidase gene, we showed that all three translational initiation sites of the P23 gene are used in vivo in both E. coli and B. subtilis, and regulation for differential expression of the three proteins during the development of B. subtilis is coupled to the transcriptional promoter switching mechanism. The physiological function of these multiple gene products is unknown and is currently under investigation.
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PMID:Developmental expression of three proteins from the first gene of the RNA polymerase sigma 43 operon of Bacillus subtilis. 304 Jun 82

Equine herpesvirus 1 (EHV-1) strain Ab4 gene 71 is predicted to encode a primary product with a M(r) of 80.1K. We have previously constructed a deletion/lacZ insertion mutant, ED71, and demonstrated that gene 71 is dispensable for growth of virus in cell culture. We have now constructed a gene 71 revertant, Re71. To identify and characterize the product of gene 71, we produced a specific antiserum, anti-71, against a beta-galactosidase fusion protein containing the carboxy terminus of the gene 71 polypeptide. Using the anti-71 serum, mutant ED71 and the revertant Re71, we have demonstrated that gene 71 encodes a 192K polypeptide. Experiments with glycosylation inhibitors revealed that the protein product of gene 71 is N-glycosylated and heavily O-glycosylated. When the 192K polypeptide is synthesized in the presence of monensin, the M(r) of the polypeptide is reduced to 80K, the predicted unmodified M(r) of the gene 71 polypeptide. The gene 71 product is found in virions and L particles in a fully processed form that runs as a diffuse band in electrophoresis, with a M(r) in excess of 200K. Immunofluorescence and virion surface labelling experiments showed that the polypeptide product of gene 71 is located on cellular membranes and the virion envelope. A time course of infection confirmed that gene 71 is regulated as a leaky late gene in infected cells. Finally, using wild-type EHV-1 Ab4, mutant ED71, revertant Re71 and two antibodies (P19 against EHV-1 glycoprotein gp300, and anti-71) we conclusively demonstrated that gene 71 encodes gp300. This contradicts published results with P19 alone, which indicated gp300 was the product of EHV-1 gene 28.
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PMID:Identification and characterization of the protein product of gene 71 in equine herpesvirus 1. 796 21

To express high levels of proteins encoded by transfected DNA constructs in a variety of cultured cells, including neuronal cells, the activities of nine different promoters were evaluated using Escherichia coli beta-galactosidase (beta-gal) (LacZ) as a reporter gene. These nine promoters were categorized into three distinct groups (high, intermediate, and low expresser), in terms of the levels of beta-gal expression. An expression vector containing the cytomegalovirus enhancer and the chick beta-actin promoter (high expresser) showed the highest levels of expression, followed by vectors containing the cytomegalovirus promoter/enhancer and the SV40 promoter/enhancer (intermediate expresser). The rest of the promoters (thymidine kinase, adenovirus, murine proliferative sarcoma virus, nerve growth factor receptor, Rous sarcoma and mouse mammary tumor virus, and beta-amyloid precursor protein) expressed low levels of beta-gal. These results were consistent for eight different cell types. A particularly attractive model is the stem cell, P19; cultures differentiating into progeny consisting predominantly of cholinergic neurons could be readily transfected with expression vectors using liposomes and expressed beta-gal without significant morphologic changes of the differentiated neurons. The systems should be useful for the study of promoters and various expressed proteins, including those involved in axonal transport.
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PMID:Activity assays of nine heterogeneous promoters in neural and other cultured cells. 806 55

The promoter and its upstream regulatory region of the mouse cellular retinoic acid-binding protein I (crabp-I) gene were examined in transgenic mouse embryos, a mouse embryonal carcinoma cell line P19, and a mouse embryonic fibroblast cell line 3T6. In transgenic mouse embryos, a beta-galactosidase reporter gene under the control of crabp-I promoter and its upstream regulatory region displayed a very specific pattern of expression characteristic of crabp-I gene expression during developmental stages. In tissue culture systems, the minimal promoter of this gene was identified, and regions containing positive and negative regulatory activities were dissected from the upstream 3-kilobase sequence using assays for transient reporter activity. It is concluded that the minimal promoter of the mouse crabp-I gene is located between 120 and 150 base pairs upstream from the transcription initiation site. Several cell type-specific positive and negative regulatory regions for this promoter have been identified. A region encoding a common negative regulatory activity in both P19 and 3T6 cells is also inhibitory to two heterologous promoters, and specific protein-DNA interactions between this DNA fragment and nuclear extracts of P19 and 3T6 are demonstrated by gel retardation experiments.
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PMID:Promoter and upstream regulatory activities of the mouse cellular retinoic acid-binding protein-I gene. 861 85

Embryonal carcinoma (EC) cells can be efficiently transfected with cloned DNAs but there is a strong tendency for expression from transfected genes to be lost from stably transformed cells. To investigate the mechanism responsible for this loss of expression, we transfected P19 EC cells with a gene encoding the E. coli beta-galactosidase and examined expression of this gene in clonal populations of cells. Cells that carry and express the beta-galactosidase gene give rise to cells that do not express at a rate of about 0.02 events per cell per cell division. These non-expressing cells were of two types, some had lost the transfected genes while others had inactivated them. In those cells that retained but inactivated the transfected genes, the inactive state was stable and suppression was at the level of transcription initiation but not associated with increased DNA methylation. Because transfected DNAs integrate into the genome as tandem arrays, the gene loss and inactivation seen in EC cells may be analogous to the repeat-induced gene inactivation seen in lower eukaryotes.
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PMID:Genes transfected into embryonal carcinoma stem cells are both lost and inactivated at high frequency. 903 47

The regulation of mouse cellular retinoic acid-binding protein-I (CRABP-I) gene expression by the retinoids and thyroid hormones was examined, by using a beta-galactosidase (lacZ) reporter gene and a CRABP-I specific antibody, in transgenic mouse embryos and a mouse embryonal carcinoma cell line P19. The CRABP-lacZ reporter gene expression recapitulated the expression pattern of endogenous CRABP-I in the developing central nervous system. In mid-gestation mouse embryos the expression of both the transgene and the endogenous protein was elevated under the condition of hypovitaminosis A, suggesting that depletion of retinoic acid (RA) induced CRABP-I expression in embryos. Consistently, this reporter was suppressed by RA in P19 cells. In co-transfection experiments it was demonstrated that the expression of RAR beta, RAR gamma or RXR alpha suppressed this reporter expression. In experiments designed to alter the thyroid hormone status in animals it was demonstrated that both the reporter gene and the endogenous CRABP-I expression were reduced by triiodothyronine injection and were elevated in a hypothyroidic condition induced by feeding with iodine-deficient diet supplemented with 6-propyl-2-thiouracil. In co-transfection experiments it was also demonstrated that the expression of T3R beta suppressed the reporter expression in P19 cells. It was concluded that RA had a suppressive effect on CRABP-I gene expression in embryos and P19 cells and the effect could be mediated through RAR beta, RAR gamma or RXR alpha. A role of thyroid hormones in CRABP-I gene expression and vitamin A metabolism in animals is discussed.
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PMID:Regulation of the mouse cellular retinoic acid-binding protein-I gene by thyroid hormone and retinoids in transgenic mouse embryos and P19 cells. 939 4

The murine Hoxa1 gene is a member of the vertebrate Hox complex and plays a role in defining the body plan during development. At day 8.0-9.0 post coitus, Hoxa1 transcripts are detected extensively throughout the embryo in the neural tube, adjacent mesenchyme, paraxial mesoderm, somites and gut epithelium; expression extends from the most caudal region of the embryo to the rhombomere 3/4 border. This spatiotemporal expression of Hoxa1 mRNA is critical for normal embryonic development. We have previously identified a 10 bp element, called CE2, which is located approximately 3 kilobases 3' of the Hoxa1 coding region in the RAIDR5 enhancer, and which binds to an approximately 170 kd protein in retinoic acid treated P19 embryonal carcinoma cells. CE2 elements were also identified 3' of the murine Hoxb1 gene, the chicken Hoxb1 gene and the human Hoxa1 gene. To examine the role of this CE2 element in regulating Hoxa1 expression in vivo, transgenic mice were generated which express a Hoxa1 beta-galactosidase reporter gene that contains a mutation in the CE2 element. Relative to transgenic mice bearing a wild type CE2 element, the mutant CE2 construct recapitulated rhombomeric, neural, and gut epithelium expression but failed to show beta-galactosidase expression in somites and adjacent mesenchymal tissue. Gel shift analysis showed that binding activity similar to that detected in extracts prepared from retinoic acid treated P19 cells was present in nuclear extracts prepared from day 9.0 embryos. However, an additional binding complex not detected in P19 cells was also observed. These results indicate that in transgenic animals, the evolutionary conserved CE2 element is a somite and adjacent mesenchymal enhancer of Hoxa1 expression.
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PMID:An evolutionary conserved element is essential for somite and adjacent mesenchymal expression of the Hoxa1 gene. 943 27

The JC virus (JCV) control region contains AGGGAAGGGA, the tandem pentanucleotide repeat element (Pnt2). Several proteins specifically interacted via Pnt2 to regulate the expression of JCV early promoter-enhancer (JCV(E)) or late promoter-enhancer (JCV(L)). In this study, a JCV Pnt2 oligonucleotide probe was used to screen a cDNA expression library from glial P19 mouse embryonal carcinoma cells. A cDNA clone was isolated by Southwestern blot assay and it produced a protein that reproducibly and specifically bound to Pnt2. This cDNA had 100% homology to one of three previously identified mouse cDNAs called cellular nucleic acid binding proteins (Cnbps). Cnbps are a highly homologous family of eukaryotic genes implicated in functional interactions with cytoplasmic RNA and regulatory DNA elements. An mRNA of 2.2 kb of Pnt2-interacting Cnbp (PCnbp) was seen in undifferentiated, muscle or glial P19 cells. When expressed from a cDNA expression vector as a fusion protein that also contained 115 kDa from beta-galactosidase, a Pnt2 binding protein (PCNBP) specifically bound to Pnt2 in Southwestern blots as a 30 kDa component of the 145 kDa fusion protein. Furthermore, JCV(E) expression was negatively regulated by PCnbp produced in vivo from the cDNA expression vector. Regulation of JCV(L) was unaffected. We suggest a novel role for CNBP as a PCNBP that interacts with Pnt2 in the negative transcriptional regulation of JCV(E).
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PMID:Identification and characterization of a JC virus pentanucleotide repeat element binding protein: cellular nucleic acid binding protein. 987 64

Because of the many superficial similarities between the immune system and the central nervous system, it has long been speculated that somatic DNA recombination is, like the immune system, involved in brain development and function. To examine whether or not the V(D)J recombination signals of the immune system work in an in vitro neural differentiation model, the P19 mouse embryonal carcinoma cell line was transfected with a reporter gene that is designed, when rearranged, to express bacterial beta-galactosidase, which was previously reported to exhibit somatic DNA recombination in the transgenic mouse brain. The cloned cells were then induced into neural cells by retinoic acid treatment. This neural induction treatment resulted in the cloning of a P19 cell line that showed a high incidence of beta-galactosidase-positive cells. Most of these beta-galactosidase-positive cells were immunocytochemically identified as either neurons, neuroepithelial cells, or astrocytes. The 5'-end sequences of the beta-galactosidase transcripts expressed in the induced cells were analyzed, and sequences were found that seemed to reflect DNA rearrangement through re-integration of the reporter gene into the host genome. However, the V(D)J recombination signals did not work in the in vitro model. These results suggested that DNA rearrangement activity though integration increased during neural differentiation of P19 cells.
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PMID:DNA rearrangement activity during retinoic acid-induced neural differentiation of P19 mouse embryonal carcinoma cells. 1576 94


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