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:3.1.30.2 (endonuclease)
18,621 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The differential induction of alpha-fetoprotein (AFP) mRNA during liver regeneration in three inbred strains of mice was examined to determine the genetic and molecular bases for the differences in protein production. BALB/cJ, C3H/He, and C57BL/6 mice, previously identified as high, intermediate, and low AFP producers, respectively, were used. Liver AFP mRNA concentrations during normal development and after carbon tetrachloride administration were measured and shown to correlate exactly with the serum protein concentrations. By performing a series of genetic crosses, we identified two unlinked genetic loci that acted independently to affect the inducibility of AFP mRNA. The raf gene, previously identified by Olsson et al. (J. Exp. Med. 145:819-827, 1977), determines the adult basal level of AFP mRNA, and the Rif gene affects its inducibility during regeneration. By using a polymorphic restriction endonuclease site within the albumin-AFP structural gene region, we show that neither regulatory gene is closely linked to the structural genes. In addition, neither gene affects the concentration of albumin mRNA during development or liver regeneration.
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PMID:Genetic analysis of alpha-fetoprotein synthesis in mice. 618 3

We have examined the DNase I sensitivity of the albumin and alpha-fetoprotein (AFP) genes in different rat tissues (adult liver and kidney) and cloned cell lines (hepatoma 7777-C8, JF1 fibroblasts), which show drastic differences in the level of expression of these two genes. This was done by studying the disappearance of defined restriction endonuclease fragments of these genes as a function of limited DNase I digestion. The sensitivity of these genes was compared to that of a gene not expressed in the hepatic cells and to that of a ubiquitously expressed gene. In nuclei from adult rat liver the albumin and AFP genes were preferentially degraded by the nucleolytic action of DNase I, whereas they were not in rat kidney nuclei. In the hepatoma cells the AFP gene was much more sensitive to DNase I digestion than the albumin gene; both genes were very resistant to DNase I action in fibroblastic nuclei. When analyzed in relation to the level of gene expression our results indicate that alterations in the chromatin structure of the albumin and AFP genes might be involved in the early establishment of the tissue-specific potential of overt gene expression; such alterations reflected in an altered DNase I sensitivity do not appear to be responsible for the changes in gene activity occurring during the terminal differentiation of the hepatocyte; and modifications in the chromatin structure of these genes might occur during oncogenic events; these structural modifications could be related to the changes in gene expression observed in hepatocarcinogenic processes.
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PMID:Differential DNase I sensitivity of the albumin and alpha-fetoprotein genes in chromatin from rat tissues and cell lines. 620 92

Homologous and heterologous hybridizations in solution were performed between sheared genomic DNA and DNA complementary to vitellogenin mRNA of Xenopus, chicken, and migratory locust. The kinetics of hybridization and the thermal stability of the hybrids formed suggested a high degree of conservation of coding sequences of insect, amphibian, and avian vitellogenin genes. These cDNA probes hybridized to calf thymus DNA to a slight, but significant, extent, and not at all to Micrococcus lysodektikus DNA. DNA complementary to Xenopus albumin mRNA did not cross-hybridize significantly with locust or chicken DNA. Further evidence for the evolutionary conservation of vitellogenin genes was obtained from Southern blot analysis of restriction endonuclease-digested genomic DNA from a variety of vertebrate and invertebrate oviparous animals (Xenopus, chicken, migratory and desert locusts, yellow meal worm, carab moth, and Mediterranean fruitfly). When probed with cloned vitellogenin cDNAs from Xenopus and migratory locust, the DNA of these organisms showed varying degrees of homology of parts of the vitellogenin coding sequences. Southern blot analysis also showed that a part of the sequence specified in the cloned Xenopus vitellogenin cDNA was represented as repetitive DNA in the locust genome. However, cloned locust vitellogenin cDNA hybridized to discrete fragments of the restricted vertebrate DNA. These studies demonstrate a remarkably high degree of conservation of insect, amphibian, and avian vitellogenin genes.
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PMID:Evolutionary conservation of vitellogenin genes. 689 73

Albumin is a developmentally regulated serum protein synthesized in the liver mainly during adulthood. Family studies using variant forms of albumin established autosomal linkage between albumin and group-specific component protein (GS). Since GC has been assigned to human chromosome 4, albumin can be indirectly assigned to the same chromosome; however no direct assignment has been made. Recently, the human albumin cDNA probe has been isolated and characterized. It thus permits a direct chromosomal assignment of the albumin gene in the human genome. When the cDNA probe was hybridized to the HindIII digested total human DNA, an intense band at 6.8 kb was present. When the probe was hybridized to the HindIII digested Chinese hamster CHO-K1 DNA, a less intense band at 3.5 kb was found, plus three other faint bands. When the probe was hybridized to a series of human/CHO-K1 cell hybrids retaining a complete hamster genome and various combinations of human chromosomes, it was evident that hybrids containing human albumin gene sequences could be readily distinguished from hybrids containing no human albumin gene. Analysis of 22 primary cell hybrids for the presence or absence of human albumin sequences has assigned the albumin gene to human chromosome 4. Similar results were obtained using another restriction endonuclease EcoR1. Thus, by direct assay of the genomic albumin gene sequences in the cell hybrids, we provide evidence for a direct assignment of the structural gene for human albumin to chromosome 4.
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PMID:Assignment of the structural gene coding for albumin to human chromosome 4. 716 10

The expression of alpha-fetoprotein (AFP) gene in a cultured normal rat liver epithelial cell line (WB-F344) and its chemical carcinogen-treated clonal derivatives was examined. WB-F344 cells expressed low levels of AFP and albumin mRNAs. Clonal cell strains and tumor cell lines derived from WB-F344 cells which had been treated multiple times with N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) showed heterogeneous levels of expression of AFP mRNA. Enhanced expression was seen in 8 of 18 (44%) cell strains/lines which expressed high gamma-glutamyltranspeptidase (GGT) activity, and in 4 of 6 (67%) of GGT-negative cell strains/lines. Southern blot analyses of DNAs after digestion by HpaII endonuclease indicated that MNNG-treated cells frequently showed hypomethylation of the AFP gene. Tumor cell lines derived from WB-F344 cells which were transformed by a single treatment with MNNG consistently expressed higher levels of AFP mRNA than tumor cell lines derived from spontaneously transformed WB-F344 cells. These results suggest that enhanced expression of AFP in MNNG-treated cultured rat liver epithelial cells may be related to the effect of treatment with this carcinogen, which is known to induce DNA hypomethylation.
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PMID:Enhanced expression of alpha-fetoprotein gene in cultured rat liver epithelial cells treated with N-methyl-N'-nitro-N-nitrosoguanidine. 769 73

Alterations of cellular functions induced by recombinant human tumor necrosis factor alpha (TNF alpha) were compared in rat hepatocytes cultured under either periportal-equivalent (10 nM insulin; 10 nM glucagon; 13% O2) or perivenous-equivalent conditions (10 nM insulin; 1 nM glucagon; 4% O2). TNF alpha induced a time- and dose-dependent increase in nitric oxide (NO) production and an acute phase response (inhibition of albumin secretion and elevation of alpha 2-macroglobulin production) under both culture conditions. NO production was more pronounced in periportal cultures, while the acute phase response was stronger in pericentral cultures. This suggests that NO production and the acute phase response are controlled by different pathways. After exposure to TNF alpha, DNA content was measured fluorimetrically and biochemically. A marked decrease in nuclear DNA content was found exclusively in pericentral cultures after an 8-h exposure, followed by an elevation of lactic dehydrogenase (LDH) release after a 12-h exposure. Aurintricarboxylic acid (100 microM), an inhibitor of endonuclease, significantly inhibited the TNF alpha-induced decrease in nuclear DNA content but only partially inhibited the LDH release. This indicates that the loss of nuclear DNA content in pericentral cultures is due to an activation of endonuclease and the resulting DNA fragmentation and does not correlate with NO production. Furthermore, the release of LDH seems to be only partially associated with DNA damage. Dexamethasone (100 nM) completely inhibited both TNF alpha-induced DNA fragmentation and the elevation of LDH release. The results clearly indicate that the toxicity of TNF alpha is influenced by the metabolic state of hepatocytes. Accordingly, the preferential perivenous cell injury observed after exposure to endotoxins in vivo seems to be due to a higher sensitivity of the pericentrally localized hepatocytes towards TNF alpha rather than a TNF alpha concentration gradient.
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PMID:Tumor necrosis factor alpha differentially modulates the cellular response of rat hepatocytes in periportal- and pericentral-equivalent cultures. 779 59

Leptospira interrogans serovar grippotyphosa was isolated from the skin of a 14-year-old male dog with deteriorating health. Necropsy revealed numerous lesions characteristic of aged dogs, but no evidence of acute hepatitis or nephritis, which are common features of pathogenic Leptospira infections. Antibody to Leptospira was not detected in the dog's serum by microagglutination. Leptospires grew slowly in Barbour-Stoenner-Kelly medium, a medium commonly used to isolate Borrelia, but then grew abundantly in Tween 80-bovine albumin leptospire medium. The isolate was pathogenic to a hamster and was identified by microagglutination and restriction endonuclease analysis.
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PMID:Isolation of Leptospira interrogans serovar grippotyphosa from the skin of a dog. 828 77

Previous work from this laboratory [Dompenciel,R.E., Garnepudi,V.R. and Schoenberg,D.R. (1995)J. Biol. Chem.270, 6108-6118] described the purification and properties of an estrogen-regulated endonuclease isolated from Xenopus liver polysomes that is involved in the destabilization of albumin mRNA. The present study mapped cleavages made by this enzyme onto the secondary structure of the portion of albumin mRNA bearing the major cleavage sites. The predominant cleavages occur in the overlapping APyrUGA sequence AUUGACUGA present in a single-stranded loop region, and in AUUGA located within a bulged AU-rich stem. A structural mutation which converted the major loop cleavage site to a hairpin bearing one APyrUGA element eliminated cleavage at the intact site. This confirms that the polysomal RNase is specific for single-stranded RNA. Additional point mutations in the major loop characterized the nucleoside sequence requirements for cleavage. Finally, snake venom exonuclease was used to demonstrate the polysomal RNase generates products with a 3' hydroxyl. Binding of an estrogen-induced protein to a portion of the 3'UTR of vitellogenin mRNA may be involved in its stabilization by estrogen [Dodson,R.E. and Shapiro,D.J. (1994)Mol. Cell. Biol.14, 3130-3138]. The core binding site for this protein bears the sequence APyrUGA, suggesting that stabilization may be accomplished by occlusion of a cleavage site for the polysomal RNase.
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PMID:Cleavage properties of an estrogen-regulated polysomal ribonuclease involved in the destabilization of albumin mRNA. 901 22

The hepatotoxicant thioacetamide (TH) has classically been used as a model to study hepatic necrosis; however, recent studies have shown that TH can also induce apoptosis. In this report we demonstrate that 2.68+/-0.54% of the albumin-SV40 T-antigen transgenic rat hepatocytes undergo TH-induced apoptosis, a level comparable to other in vivo models of liver apoptosis. In addition, TH could induce apoptosis and necrosis in the L37 albumin-SV40 T-antigen transgenic rat liver-derived cell line. Examination of dying L37 cells treated with 100 mM TH by electron microscopy revealed distinct morphological characteristics that could be attributed to apoptosis. Quantitation of apoptosis by FACS analysis 24 h after treatment with 100 mM TH revealed that 81.3+/-1.6% of the cells were undergoing apoptosis. In contrast, when L37 cells were treated with 250 mM TH, cells exhibited characteristics consistent with necrotic cell death. DNA fragmentation ladders were produced by growth factor withdrawal-induced apoptosis; however, in 100 mM TH-induced apoptosis, DNA fragmentation ladders were not observed. Analysis of endonuclease activity in L37 cells revealed that the enzymes were not inactivated in the presence of 100 mM TH. The data presented in this report indicate that the L37 cell line could be used to study the mechanism of TH-induced apoptosis that was not mediated through a mechanism requiring DNA fragmentation.
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PMID:The mechanism of thioacetamide-induced apoptosis in the L37 albumin-SV40 T-antigen transgenic rat hepatocyte-derived cell line occurs without DNA fragmentation. 979 20

We have purified an approximately 60 kDa endoribonuclease from Xenopus liver polysomes with properties expected for a messenger RNase involved in the estrogen-regulated destabilization of serum protein mRNAs (Dompenciel et al., 1995, J Biol Chem 270:6108-6118). The present report describes the cloning of this protein and its identification as a novel member of the peroxidase gene family. This novel enzyme, named polysomal RNase 1, or PMR-1 has 57% sequence identity with myeloperoxidase, and like that protein, appears to be processed from a larger precursor. Unlike myeloperoxidase, however, PMR-1 lacks N-linked oligosaccharide, heme, and peroxidase activity. Western blot and immunoprecipitation experiments using epitope-specific antibodies to the derived protein sequence confirm the identity of the cloned cDNA to the protein originally isolated from polysomes. The 80 kDa pre-PMR-1 expressed in a recombinant baculovirus was not processed to the 60 kDa form in Sf9 cells and lacks RNase activity. However, the baculovirus-expressed mature 60-kDa form of the enzyme has RNase activity. The recombinant protein is an endonuclease that shows selectivity for albumin versus ferritin mRNA. While it does not cleave at consensus APyrUGA elements, recombinant PMR-1 generates the same minor cleavage products from albumin mRNA as PMR-1 purified from liver. Finally, we show estrogen induces only a small increase in the amount of PMR-1. This result is consistent with earlier data suggesting estrogen activates mRNA decay through a posttranslational pathway.
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PMID:A polysomal ribonuclease involved in the destabilization of albumin mRNA is a novel member of the peroxidase gene family. 984 52


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