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)

The vertebrate Slug gene encodes a zinc finger-containing transcriptional repressor. Here we report expression of the mouse Slug gene during organogenesis and late fetal development using histochemical detection of beta-galactosidase expressed from a targeted Slug(lacZ) knock-in allele. The Slug gene is highly expressed in the mesenchymal or stromal component of numerous organs. It is also highly expressed in craniofacial mesenchyme, in bone of both mesodermal and neural crest origin, and in the outflow tract and the endocardial cushions of the heart.
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PMID:Slug expression during organogenesis in mice. 1255 34

Oral streptococci, such as Streptococcus gordonii, are the predominant early colonizers that initiate biofilm formation on tooth surfaces. Investigation of an S. gordonii::Tn917-lac biofilm-defective mutant isolated by using an in vitro biofilm formation assay showed that the transposon insertion is near the 3' end of an open reading frame (ORF) encoding a protein homologous to Streptococcus mutans FruK. Three genes, fruR, fruK, and fruI, were predicted to encode polypeptides that are part of the fructose phosphotransferase system (PTS) in S. gordonii. These proteins, FruR, FruK, and FruI, are homologous to proteins encoded by the inducible fruRKI operon of S. mutans. In S. mutans, FruR is a transcriptional repressor, FruK is a fructose-1-phosphate kinase, and FruI is the fructose-specific enzyme II (fructose permease) of the phosphoenolpyruvate-dependent sugar PTS. Reverse transcription-PCR confirmed that fruR, fruK, and fruI are cotranscribed as an operon in S. gordonii, and the transposon insertion in S. gordonii fruK::Tn917-lac resulted in a nonpolar mutation. Nonpolar inactivation of either fruK or fruI generated by allelic replacement resulted in a biofilm-defective phenotype, whereas a nonpolar mutant with an inactivated fruR gene retained the ability to form a biofilm. Expression of fruK, as measured by the beta-galactosidase activity of the fruK::Tn917-lac mutant, was observed to be growth phase dependent and was enhanced when the mutant was grown in media with high levels of fructose, sucrose, xylitol, and human serum, indicating that the fructose PTS operon was fructose and xylitol inducible, similar to the S. mutans fructose PTS. The induction by fructose was inhibited by the presence of glucose, indicating that glucose is able to catabolite repress fruK expression. Nonpolar inactivation of the fruR gene in the fruK::Tn917-lac mutant resulted in a greater increase in beta-galactosidase activity when the organism was grown in media supplemented with fructose, confirming that fruR is a transcriptional repressor of the fructose PTS operon. These results suggest that the regulation of fructose transport and metabolism in S. gordonii is intricately tied to carbon catabolite control and the ability to form biofilms. Carbon catabolite control, which modulates carbon flux in response to environmental nutritional levels, appears to be important in the regulation of bacterial biofilms.
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PMID:Involvement of an inducible fructose phosphotransferase operon in Streptococcus gordonii biofilm formation. 1456 58

The Armadillo catenin p120(ctn) regulates cadherin adhesive strength at the plasma membrane and interacts with the novel BTB/POZ transcriptional repressor Kaiso in the nucleus. The dual localization of p120(ctn) at cell-cell junctions and in the nucleus suggests that its nucleocytoplasmic trafficking is tightly regulated. Here we report on the identification of a specific and highly basic nuclear localization signal (NLS) in p120(ctn). The functionality of the NLS was validated by its ability to direct the nuclear localization of a heterologous beta-galactosidase-GFP fusion protein. Mutating two key positively charged lysines to neutral alanines in the NLS of full-length p120(ctn) inhibited both p120(ctn) nuclear localization as well as the characteristic p120(ctn)-induced branching phenotype that correlates with increased cell migration. However, while these findings and others suggested that nuclear localization of p120(ctn) was crucial for the p120(ctn)-induced branching phenotype, we found that forced nuclear localization of both wild-type and NLS-mutated p120(ctn) did not induce branching. Recently, we also found that one role of p120(ctn) was to regulate Kaiso-mediated transcriptional repression. However, it remained unclear whether p120(ctn) sequestered Kaiso in the cytosol or directly inhibited Kaiso transcriptional activity in the nucleus. Using minimal promoter assays, we show here that the regulatory effect of p120(ctn) on Kaiso transcriptional activity requires the nuclear translocation of p120(ctn). Therefore, an intact NLS in p120(ctn) is requisite for its first identified regulatory role of the transcriptional repressor Kaiso.
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PMID:NLS-dependent nuclear localization of p120ctn is necessary to relieve Kaiso-mediated transcriptional repression. 1513 84

Carbon catabolite repression by the CreA-transcriptional repressor is widespread in filamentous fungi, but the mechanism by which glucose triggers carbon catabolite repression is still poorly understood. We investigated the hypothesis that the growth rate on glucose may control CreA-dependent carbon catabolite repression by using glucose-limited chemostat cultures and the intracellular beta-galactosidase activity of Aspergillus nidulans, which is repressed by glucose, as a model system. Chemostat cultures at four different dilution rates (D = 0.095, 0.068, 0.045 and 0.015 h-1) showed that formation of beta-galactosidase activity is repressed at the two highest Ds, but increasingly derepressed at the lower Ds, the activity at 0.015 h-1 equalling that in derepressed batch cultures. Chemostat cultures with the carbon catabolite derepressed A. nidulans mutant strain creADelta4 revealed a dilution-rate independent constant beta-galactosidase activity of the same range as that found in the wild-type strain at D = 0.015 h-1. Two other enzymes--isocitrate lyase, which is almost absent on glucose due to a CreA-independent mechanism; and galactokinase, which is formed constitutively and independent of CreA--were measured as controls. They were formed at constant activity at each dilution rate, both in the wild-type strain as well as in the carbon catabolite derepressed mutant strain. We conclude that the growth rate on glucose is a determinant of carbon catabolite repression in A. nidulans, and that below a certain growth rate carbon catabolite derepression occurs.
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PMID:CreA-mediated carbon catabolite repression of beta-galactosidase formation in Aspergillus nidulans is growth rate dependent. 1515 74

Kaiso is a BTB/POZ transcription factor that functions in vitro as a transcriptional repressor of the matrix metalloproteinase gene matrilysin and the non-canonical Wnt signaling gene Wnt-11, and as an activator of the acetylcholine-receptor-clustering gene rapsyn. Similar to other BTB/POZ proteins (e.g. Bcl-6, PLZF, HIC-1), endogenous Kaiso localizes predominantly to the nuclei of mammalian cells. To date, however, the mechanism of nuclear import for most POZ transcription factors, including Kaiso, remain unknown. Here, we report the identification and characterization of a highly basic nuclear localization signal (NLS) in Kaiso. The functionality of this NLS was verified by its ability to target a heterologous beta-galactosidase/green-fluorescent-protein fusion protein to nuclei. The mutation of one positively charged lysine to alanine in the NLS of full-length Kaiso significantly inhibited its nuclear localization in various cell types. In addition, wild-type Kaiso, but not NLS-defective Kaiso, interacted directly with the nuclear import receptor Importin-alpha2 both in vitro and in vivo. Finally, minimal promoter assays using a sequence-specific Kaiso-binding-site fusion with luciferase as reporter demonstrated that the identified NLS was crucial for Kaiso-mediated transcriptional repression. The identification of a Kaiso NLS thus clarifies the mechanism by which Kaiso translocates to the nucleus to regulate transcription of genes with diverse roles in cell growth and development.
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PMID:Nuclear import of the BTB/POZ transcriptional regulator Kaiso. 1556 77

ETV6, or Translocation-Ets-Leukemia (TEL), is an ETS family transcriptional repressor that is essential for establishing hematopoiesis in neonatal bone marrow, and is frequently a target of chromosomal translocations in human cancer. ETV6 is predominantly a nuclear phosphoprotein that represses transcription by binding directly to the promoters of target genes. The nuclear localization mechanism of ETV6, however, is not well understood. In this report, we provide evidence that a nuclear localization signal (NLS) exists in the C-terminal region of ETV6. ETV6 proteins with mutations outside of amino acids 332-452 localize to the nucleus, whereas proteins with mutations within amino acids 332-452 remain in the cytoplasm. Furthermore, when a fragment of ETV6 comprised of amino acids 332-452 was fused to cytoplasmic beta-galactosidase protein, the fusion protein was able to enter the nucleus. These results strongly indicate that residues 332-452 mediate nuclear localization of ETV6.
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PMID:Identification of the nuclear localization motif in the ETV6 (TEL) protein. 1673 10

MBP-1 acts as a general transcriptional repressor. Overexpression of MBP-1 induces cell death in a number of cancer cells and regresses tumor growth. However, the function of endogenous MBP-1 in normal cell growth regulation remains unknown. To unravel the role of endogenous MBP-1, we knocked down MBP-1 expression in primary human foreskin fibroblasts (HFF) by RNA interference. Knockdown of MBP-1 in HFF (HFF-MBPsi-4) resulted in an induction of premature senescence, displayed flattened cell morphology, and increased senescence-associated beta-galactosidase activity. FACS analysis of HFF-MBPsi-4 revealed accumulation of a high number of cells in the G1-phase. A significant upregulation of cyclin D1 and reduction of cyclin A was detected in HFF-MBPsi-4 as compared to control HFF. Senescent fibroblasts exhibited enhanced expression of phosphorylated and acetylated p53, and cyclin-dependent kinase inhibitor, p21. Further analysis suggested that promyolocytic leukemia protein (PML) bodies are dramatically increased in HFF-MBPsi-4. Together, these results demonstrated that knockdown of endogenous MBP-1 is involved in cellular senescence of HFF through p53-p21 pathway.
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PMID:Knockdown of MBP-1 in human foreskin fibroblasts induces p53-p21 dependent senescence. 1885 84

Penicillium canescens strain F178 is a natural producer of beta-galactosidase and endo-1,4-beta-xylanase. Tanscription of genes bgaS and xylA coding for these proteins is subject to carbon catabolite repression which proceed mainly in filamentous fungi by transcriptional repressor CreA. creA gene of P. canescens was cloned. It was demonstrated that creA transcription is also subject to carbon catabolite repression. CreA protein remains intranuclear independently of nature of carbon source and glucose concentration in culture medium. In vitro experiments confirm availability of four CreA-binding sites in bgaS promoter, four sites in xylA promoter and one such site in creA promoter.
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PMID:[Transcriptional regulator of carbon catabolite repression CreA in filamentous fungus]. 2087 28


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