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:3.2.1.31 (beta-glucuronidase)
7,680 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The causation, structural origin, and mechanism of formation of spongiform lesions in transmissible encephalopathies are unknown. We have used immunogold electron microscopy to locate ubiquitin conjugates, hsp 70, and beta-glucuronidase (markers of the lysosomal compartment) and prion protein (PrP) in both control and scrapie-infected mouse brain. In scrapie-infected brain, lysosomes and lysosome-related structures (multivesicular and tubulovesicular dense bodies) are present in abnormally high numbers in neuronal cell processes. These structures contain PrP, together with the lysosomal markers ubiquitin conjugates, hsp 70, and beta-glucuronidase, which could also be identified spilling from tubulovesicular dense bodies into areas of early rarefaction in neuronal processes; we suggest that these areas of rarefaction are the precursor lesions of spongiform change. We advance the hypothesis that spongiform change is brought about by cytoskeletal disruption in neuronal processes caused by liberation of hydrolytic enzymes from lysosomes overloaded with the abnormal isoform of PrP (PrPsc). We suggest that the lysosomal system is probably acting as the bioreactor for processing of normal PrP to the abnormal isoform. The continuous production of increasing quantities of abnormal PrPsc in lysosome-related bodies will eventually cause disruption of the lysosomal membrane with destruction of the neuronal cytoskeleton and the initiation of vacuolation. Later, death of the cell will be associated with release of the PrPsc isoform into the extracellular environment. Repeated rounds of phagocytosis, lysosomal biogenesis of PrPsc, lysosomal membrane rupture, hydrolytic enzyme release, and neuronal lysis will lead to an exponential increase in cell damage and cell death.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Lysosomes as key organelles in the pathogenesis of prion encephalopathies. 135 30

The bacterial gene encoding beta-glucuronidase (GUS) was transiently expressed in cassava leaves following the introduction of the gene by microparticle bombardment. The DNA expression vector used to introduce the reporter gene is a pUC 19 derivative and consisted of a CaMV 35S promoter (P35S), the GUS coding region and 7S polyadenylation region. Several other promoters and regulating sequences were tested for efficiency in cassava leaves. Two derivatives of the P35S, one including a partial duplication of the upstream region of the P35S and the other containing a tetramer of the octopine synthase enhancer, were found to be expressed at three times the level of the P35S in cassava leaves. The ubiquitin 1 promoter from Arabidopsis thaliana was expressed at the same level as the P35S. No influence on the level of expression was observed when different 3' ends were used. The biolistic transient gene expression system in cassava leaves allows rapid analysis of gene constructs and can serve as a preliminary screen for chimeric gene function in the construction of transgenic cassava plants.
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PMID:Transient gene expression in cassava using high-velocity microprojectiles. 165 61

The highly conserved protein ubiquitin is synthesized in eukaryotes as two types of protein fusions from which active ubiquitin is derived by proteolytic processing. We report here the isolation and characterization of multiple genes from one type that encode ubiquitin extension proteins from the higher plant, Arabidopsis thaliana (L.). Two genes with 90% nucleotide identity in their exons encode ubiquitin and identical 52-amino acid (aa) extension proteins with 85 and 79% aa identity to 52-aa extension proteins from humans and yeast, respectively. Two other genes with 90% nucleotide identity encode ubiquitin and 81-aa extension proteins that differ by 4 amino acids from each other and are approximately 70% identical to the 76- and the 80-aa extension proteins from yeast and humans, respectively. Antibodies recognizing the 52- and 81-aa Arabidopsis extension proteins identify them as constituents of ribosomes. By sodium dodecyl sulfate-polyacrylamide gel electrophoresis, the 52- and 81-aa extension proteins migrate at 6.8 and 11.5 kDa, respectively, and neither cross-reacts with anti-ubiquitin antibodies, indicating that extension proteins are cleaved from ubiquitin following translation. Ubiquitin extension protein genes encode the smallest transcript size class of ubiquitin mRNAs in Arabidopsis. The 5'-flanking regions of both UBQ1 and UBQ6, genes representative of the both extension proteins, direct the expression of readily detectable levels of the marker enzyme beta-glucuronidase in transgenic tobacco, suggesting the utility of these promoters for expression of foreign genes in higher plants.
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PMID:Ubiquitin extension proteins of Arabidopsis thaliana. Structure, localization, and expression of their promoters in transgenic tobacco. 216 66

The expression of various components of the lysosomal and ubiquitin-dependent degradative pathways was characterized in an in vitro model of differentiating enterocytes, the human colon adenocarcinoma Caco-2 cell line. The activities of the cell-associated lysosomal enzymes alpha-D-mannosidase, beta-hexosaminidase, beta-glucuronidase, and beta-galactosidase increased approximately 2- to 4-fold as differentiation proceeded. In contrast, the protein levels of the two mannose 6-phosphate receptors (MPRs), the insulin-like growth factor II/cation-independent MPR (IGF-II/CI-MPR) and the cation-dependent MPR (CD-MPR), did not change significantly during Caco-2 differentiation. In addition, quantitative Western blot analyses revealed that on a molar basis the CD-MPR is 3.5 times more abundant than the IGF-II/CI-MPR in Caco-2 cells. Since only limited secretion of lysosomal enzymes was observed throughout differentiation, the level of expression of the MPRs was sufficient to target the increased levels of lysosomal enzymes to the lysosome. Unlike the expression of lysosomal enzymes, Western blot analysis demonstrated an approximately 40% and approximately 30% decrease, respectively, in the steady-state levels of free and conjugated ubiquitin during Caco-2 differentiation. Taken together, these results show that the ubiquitin-dependent proteolytic pathway is regulated differently than the lysosomal degradative pathway during Caco-2 differentiation.
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PMID:Regulation of lysosomal and ubiquitin degradative pathways in differentiating human intestinal Caco-2 cells. 754 43

The prion encephalopathies are characterized by accumulation in the brain of the abnormal form PrPsc of a normal host gene product PrPc. The mechanism and site of formation of PrPsc from PrPc are currently unknown. In this study, ME7 scrapie-infected mouse brain was used to show, both biochemically and by double-labelled immunogold electron microscopy, that proteinase K-resistant PrPsc is enriched in subcellular structures which contain the cation-independent mannose 6-phosphate receptor, ubiquitin-protein conjugates, beta-glucuronidase, and cathepsin B, termed late endosome-like organelles. The glycosylinositol phospholipid membrane-anchored PrPc will enter such compartment for normal degradation and the organelles may therefore act as chambers for the conversion of PrPc into infectious PrPsc in this murine model of scrapie.
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PMID:The abnormal isoform of the prion protein accumulates in late-endosome-like organelles in scrapie-infected mouse brain. 756 56

The nitrate reductase (NR) gene niaA of the oomycete Phytophthora infestans was selected from a gene library by heterologous hybridization. NiaA occurs as a single-copy gene ant its expression is regulated by the nitrogen source. The nucleotide sequence of niaA was determined and comparison of the deduced amino-acid sequence of 902 residues with NRs of higher fungi and plants revealed a significant homology, particularly within the three cofactor-binding domains for molybdenum, heme and FAD. The P. infestans niaA gene was used as a model gene to test whether oomycete genes are functional in the ascomycete Aspergillus nidulans, a fungus which is highly accessible for molecular genetic studies. The complete niaA gene was stably integrated into the genome of a nia- deletion mutant of A. nidulans. However, transformants containing one or more copies of the niaA gene were not able to complement the nia- mutant. This suggests that there is no functional expression of the introduced niaA gene in A. nidulans. In addition, the activity of two other oomycete gene promoters was analyzed in a transient expression assay. Plasmids containing chimaeric genes with the promoter of the P. infestans ubiquitin gene ubi3R, or the Bremia lactucae ham34 gene, fused to the coding sequence of the Escherichia coli beta-glucuronidase (GUS) reporter gene, were transferred to A. nidulans protoplasts. No significant GUS activity was detectable indicating that the ubi3R and ham34 promoters are not active in A. nidulans. Apparently, the regulatory sequences which are sufficient for gene activation in oomycetes are not functional in the ascomycete A. nidulans.
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PMID:NiaA, the structural nitrate reductase gene of Phytophthora infestans: isolation, characterization and expression analysis in Aspergillus nidulans. 761 59

A genomic clone encoding the potato homolog of the yeast ubiquitin-ribosomal protein fusion gene ubi3 was isolated and characterized. Chimeric genes containing the ubi3 promoter (920 bp of 5' to the ubiquitin start codon) were constructed in which the reporter gene beta-glucuronidase (GUS) was either fused directly to the promoter, or introduced as a translational fusion to the ubiquitin-coding region. After introduction into the potato by Agrobacterium-mediated transformation, GUS activities were measured in leaves and in tubers of transgenic clones. GUS activity was 5- to 10-fold higher in clones expressing the ubiquitin-GUS translational fusion than in clones containing GUS fused directly to the ubi3 promoter. For both types of constructs, GUS activity was highest in meristematic leaves and declined during leaf expansion, then rose again to near the meristematic levels during senescence. GUS activity in tubers was similar to that in young leaves. In contrast to the native ubi3 genes, the chimeric ubi3-GUS transgenes were not activated in the tuber by wounding.
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PMID:Isolation of a ubiquitin-ribosomal protein gene (ubi3) from potato and expression of its promoter in transgenic plants. 811 Oct 11

The motor neuron degeneration (Mnd) mutation in the mouse is a late onset, autosomal dominant, neurodegenerative disease in which ventral horn neurons have been shown to contain numerous, large cytoplasmic inclusions. Histochemical and immunocytochemical studies performed on spinal cord from Mnd/Mnd mice in late stages of the disease showed the inclusions to contain protein, lipid and carbohydrate moieties. Spinal neurons, especially those in spinal lamina IX, contained increased beta-glucuronidase activity in the form of large cytoplasmic inclusions. Such inclusions also contained increased acid phosphatase and trimetaphosphatase activity. When immunostained with antiubiquitin antibodies, intracellular ubiquitin deposits were present as accumulations of varying size; some were amorphous while others contained small granules. Extraneuronal ubiquitin deposits were detected in the neuropil. Immunostaining with monoclonal antibody ML30, used here to assay for the presence of a mitochondrial epitope in the inclusions, was widespread and punctate in white and grey matter from Mnd/Mnd and age-matched control spinal cords. The overall pattern of staining was similar for both tissue sources and did not correspond to any of the other probes which reacted with the inclusions in Mnd neurons. The presence of increased levels of lysosomal hydrolases and ubiquitinated molecules suggests that the two general systems for intracellular digestion are activated in Mnd/Mnd spinal neurons.
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PMID:Cytoplasmic inclusions in spinal neurons of the motor neuron degeneration (Mnd) mouse. I. Light microscopic analysis. 838 15

A polyubiquitin clone (ubi7) was isolated from a potato (Solanum tuberosum) genomic library using a copy-specific probe from a stress-induced ubiquitin cDNA. The genomic clone contained a 569-bp intron immediately 5' to the initiation codon for the first ubiquitin-coding unit. Two chimeric beta-glucuronidase (GUS) fusion transgenes were introduced into potato. The first contained GUS fused to a 1156-bp promoter fragment containing only 5' flanking and 5' untranslated sequences from ubi7. The second transgene contained GUS translationally fused to the carboxy terminus of the first ubiquitin-coding unit and thus included the intron present in the 5' untranslated region of the polyubiquitin gene. Both ubi7-GUS transgenes were activated by wounding in tuber tissue and in leaves by application of exogenous methyl jasmonate. They were also expressed constitutively in the potato tuber peel (outer 1-2 mm). Both transgenes were actively expressed in mature leaves. Exceptionally high levels of expression were observed in senescent leaves. Transgenic clones containing the ubi7 intron and the first ubiquitin-coding unit showed GUS expression levels at least 10 times higher than clones containing GUS fused to the intronless promoter.
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PMID:Isolation of a polyubiquitin promoter and its expression in transgenic potato plants. 853 96

A set of plasmids has been constructed utilizing the promoter, 5' untranslated exon, and first intron of the maize ubiquitin (Ubi-1) gene to drive expression of protein coding sequences of choice. Plasmids containing chimaeric genes for ubiquitin-luciferase (Ubi-Luc), ubiquitin-beta-glucuronidase (Ubi-GUS), and ubiquitin-phosphinothricin acetyl transferase (Ubi-bar) have been generated, as well as a construct containing chimaeric genes for both Ubi-GUS and Ubi-bar in a single plasmid. Another construct was generated to allow cloning of protein coding sequences of choice on Bam HI and Bam HI-compatible restriction fragments downstream of the Ubi-1 gene fragment. Because the Ubi-1 promoter has been shown to be highly active in monocots, these constructs may be useful for generating high-level gene expression of selectable markers to facilitate efficient transformation of monocots, to drive expression of reference reporter genes in studies of gene expression, and to provide expression of biotechnologically important protein products in transgenic plants.
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PMID:Ubiquitin promoter-based vectors for high-level expression of selectable and/or screenable marker genes in monocotyledonous plants. 867 50


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