Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0019158 (hepatitis)
 30,205 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We previously demonstrated that both casein kinase II (CKII) and protein kinase C (PKC) positively modulate the hepatitis delta virus (HDV) RNA replication but not the assembly of the empty hepatitis delta antigen (HDAg) particle. In this study, we investigated whether phosphorylation of HDAg by these two kinases plays a role in assembly of the HDV virion. As demonstrated by in vivo labeling and kinase inhibitor experiments, the phosphorylation level of large HDAg but not small HDAg in HDAg-expressing HuH-7 cells was diminished by CKII inhibitor (DRB), whereas no effect was observed for the phosphorylation level of two HDAgs when treated with protein kinase A (PKA) inhibitor (HA1004) or PKC inhibitor (H7). Cotransfection experiment also demonstrated that packaging of HDV genomic RNA was not affected by the kinase inhibitor DRB or H7 and mutation at the putative CKII phosphorylation sites (serine-2, serine-123, or both), and the putative PKC site (serine-210) of HDAg did not elicit any significant effect on the HDV virion assembly. Therefore, based on the previous work and the present study, it seems that the status and biological significance of phosphorylation of HDAg vary depending on the HDV life cycle. Although in the HDV RNA replication cycle, phosphorylation of small HDAg by CKII or PKC plays important role in HDV replication, phosphorylation of the same HDAg by these two kinases does not occur during the HDV RNA virion assembly, and phosphorylation of the large HDAg by CKII does not confer any regulatory role in the assembly of HDV virion and empty viral particles. Our study also showed that the large HDAg without the small HDAg could efficiently assemble both monomeric and dimeric HDV genomic RNAs into secreted HBV-enveloped virus-like particles. Increasing the transfected small HDAg-expressing plasmid led to an enhancement of the packaging efficiency for the monomeric HDV genomic RNA with little effect on the packaging of dimeric HDV RNA. Similarly, HDAgs could package the trimeric HDV genomic RNA, albeit less efficiently. CsCl density gradient centrifugation confirmed that HDAgs and the monomeric and multimeric (dimer and trimer) HDV genomic RNAs formed an HBV-enveloped virus-like particle at a density of 1.23-1.25 g/ml. Thus, the assembly of the HDV virion seems to not impose much restriction on the size of HDV RNA for packaging.
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PMID:Assembly of hepatitis delta virus particles: package of multimeric hepatitis delta virus genomic RNA and role of phosphorylation. 974 Jul 72

The mouse hepatitis virus (MHV) membrane (M) protein contains only O-linked oligosaccharides. We have used this protein as a model to study the structural requirements for O-glycosylation. We show that MHV M is modified by the addition of a single oligosaccharide side chain at the cluster of 4 hydroxylamino acids present at its extreme amino terminus and identified Thr at position 5 as the functional acceptor site. The hydroxylamino acid cluster, which is quite conserved among O-glycosylated coronavirus M proteins, is not in itself sufficient for O-glycosylation. Downstream amino acids are required to introduce a functional O-glycosylation site into a foreign protein. In a mutagenic analysis O-glycosylation was found to be sensitive to some particular changes but no unique sequence motif for O-glycosylation could be identified. Expression of mutant M proteins in cells revealed that substitution of any 1 residue was tolerated, conceivably due to the occurrence of multiple UDP-N-acetylgalactosamine:polypeptide N-acetylgalactosaminyltransferases (GalNAc transferases). Indeed, MHV M served as a substrate for GalNac-T1, -T2, and -T3, as was demonstrated using an in situ glycosylation assay based on the co-expression of endoplasmic reticulum-retained forms of the GalNAc transferases with endoplasmic reticulum-resident MHV M mutants. The GalNAc transferases were found to have largely overlapping, but distinct substrate specificities. The requirement for a threonine as acceptor rather than a serine residue and the requirement for a proline residue three positions downstream of the acceptor site were found to be distinctive features.
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PMID:Structural requirements for O-glycosylation of the mouse hepatitis virus membrane protein. 979 8

A novel copper-binding protein was identified in the liver supernatant (100,000 x g) of Indian childhood cirrhosis (ICC), purified to apparent homogeneity and characterized [corrected]. Purified major copper-binding protein (MCuBP) is solely responsible for binding about 35% of the total supernatant copper. Elution profile of ICC liver supernatant on Sephadex G-75 column chromatography showed three peaks. About 60% of the total supernatant copper was resolved in peak II, whereas zinc content was insignificant in this peak. But peak II was almost missing in a gel elution profile of control liver supernatant. The control group included cases of various liver diseases viz. neonatal hepatitis, septicemia, and mixed nodular cirrhosis. Copper-binding proteins of peak II further purified on ion-exchange chromatography and elution profile showed that peak II was a MCuBP with high copper-binding capacity (10 g atoms/mol of native protein). SDS-PAGE of this protein also revealed the existence of a single band with molecular mass of about 50 kD. UV spectra of MCuBP showed the maximal absorbance at 254 nm. Unlike the classical metallothionein, the amino acid composition of MCuBP revealed the presence of aromatic amino acids and higher content of glutamic acid and aspartic acid followed by glycine and serine. The ratio (0.3) of basic amino acids to acidic amino acids strongly indicates that it is an acidic protein. The cysteine content in this protein was insignificant, which further corroborates the possibility that the acidic amino acids might be prominent candidates for binding copper. Thus, the 50-kD MCuBP apparently makes a major contribution to the total copper-binding activity in ICC liver cytosol and may play a significant role in hepatic intracellular copper accumulation.
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PMID:Identification of a novel copper-binding protein from the liver of Indian childhood cirrhosis: purification and physicochemical characterization [corrected]. 980 48

Activity was studied of blood serum plasmic enzymes L-serine and L-threonine dehydrogenazes (SDG and ThDG) in 92 liquidators of aftermath of the Chernobyl atomic power plant breakdown, presenting with chronic non-calculous cholecystitis during the stage of moderately severe exacerbation with no clinical and laboratory and sonographic signs of affection of the liver. A quarter of the examinees demonstrated an increased activity of the enzymes under study, which fact is regarded by the authors as a preclinical sign of reactive hepatitis. Recommendations are given as to the outpatient registration and prophylactic management and therapy of those persons having taken part in the elimination of the effects of the Chernobyl accident, presenting with biliary pathologies.
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PMID:[Changes in the L-serine and L-threonine dehydrogenase activities in the blood serum of those who worked in the cleanup of the aftermath of the accident at the Chernobyl Atomic Electric Power Station who became ill with chronic acalculous cholecystitis]. 1047 30

Hepatitis C virus (HCV) is the cause of the majority of transfusion-associated hepatitis and a significant proportion of community-acquired hepatitis worldwide. Infection by HCV frequently leads to persistent infections that result in a range of clinical conditions including an asymptomatic carrier state, severe chronic active hepatitis, cirrhosis and, in some cases, hepatocellular carcinoma. The HCV genome consists of a single-stranded, positive sense RNA containing an open reading frame of approximately 9060 nucleotides. This is translated into a single polyprotein of approximately 3020 amino acids (C-E1-E2-p7-NS2-NS3-NS4A-NS4B-NS5A-NS5B), which in turn is processed by a series of host and viral proteinases into at least 10 cleavage products. The N-terminal portion of the NS3 protein encodes a serine proteinase that is responsible for the cleavage at the NS3-4A, NS4A-4B, NS4B-5A and NS5A-5B junctions. The 54 amino acid NS4A protein is a cofactor that binds to the NS3 protein and enhances its proteolytic activity. This report describes the expression of a recombinant NS3-4A proteinase fusion protein in Escherichia coli and the in vitro characterization of the enzyme activity using synthetic peptide substrates. It then demonstrates how these results were employed to guide the design of potent inhibitors of this enzyme.
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PMID:The design and synthesis of potent inhibitors of hepatitis C virus NS3-4A proteinase. 1057 81

The hepatitis C virus (HCV) is a major causative agent of transfusion-acquired and sporadic non-A, non-B hepatitis worldwide. Infections most often persist and lead, in approximately 50% of all patients, to chronic liver disease. As is characteristic for a member of the family Flaviviridae, HCV has a plus-strand RNA genome encoding a polyprotein, which is cleaved co- and post-translationally into at least 10 different products. These cleavages are mediated, among others, by a virally encoded chymotrypsin-like serine proteinase located in the N-terminal domain of non-structural protein 3 (NS3). Activity of this enzyme requires NS4A, a 54-residue polyprotein cleavage product, to form a stable complex with the NS3 domain. This review will describe the biochemical properties of the NS3/4A proteinase, its X-ray crystal structure and current attempts towards development of efficient inhibitors.
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PMID:The NS3/4A proteinase of the hepatitis C virus: unravelling structure and function of an unusual enzyme and a prime target for antiviral therapy. 1060 29

Infection with the hepatitis C virus (HCV) is the major cause of nonA-nonB hepatitis worldwide. Although this virus cannot be cultivated in vitro, several of its key features have been elucidated in the past few years. The viral genome is a positive-sense, single-stranded, 9.6 kb long RNA molecule. The viral genome is translated into a single polyprotein of about 3000 amino acids. The viral polyprotein is proteolytically processed by the combination of cellular and viral proteinases in order to yield all the mature viral gene products. The genomic order of HCV has been shown to be C-E1-E2-p7-NS2-NS3-NS4A-NS4B-NS5A-NS5B. C, E1 and E2 are the virion.structural proteins. The function of p7 is currently unknown. These proteins have been shown to arise from the viral polyprotein via proteolytic processing by the host signal peptidases. Generation of the mature nonstructural proteins, NS2 to NS5B, relies on the activity of viral proteinases. Cleavage at the NS2/NS3 junction is accomplished by a metal-dependent autocatalytic proteinase encoded within NS2 and the N-terminus of NS3. The remaining cleavages downstream from this site are effected by a serine proteinase also contained within the N-terminal region of NS3. NS3 also contains an RNA helicase domain at its C-terminus. NS3 forms a heterodimeric complex with NS4A. The latter is a membrane protein that has been shown to act as a cofactor of the proteinase. While no function has yet been attributed to NS4B, it has recently been suggested that NS5A is involved in mediating the resistance of the hepatitis C virus to the action of interferon. Finally, the NS5B protein has been shown to be the viral RNA-dependent RNA polymerase.
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PMID:Molecular virology of the hepatitis C virus. 1062 60

Infection with the hepatitis C virus (HCV) is the major cause of non-A, non-B hepatitis worldwide. The viral genome, a positive-sense, single-stranded, 9.6-kb long RNA molecule, is translated into a single polyprotein of about 3,000 amino acids. The viral polyprotein is proteoytically processed to yield all the mature viral gene products. The genomic order of HCV has been determined to be C-->E1-->E2-->p7-->NS2-->NS3-->NS4A-->NS4B-->NS5A++ +-->NS5B. C, E1, and E2 are the virion structural proteins. Whereas the function of p7 is currently unknown, NS2 to NS5B are thought to be the nonstructural proteins. Generation of the mature nonstructural proteins relies on the activity of viral proteinases. Cleavage at the NS2-NS3 junction is accomplished by a metal-dependent autocatalytic proteinase encoded within NS2 and the N-terminus of NS3. The remaining downstream cleavages are effected by a serine proteinase contained also within the N-terminal region of NS3. NS3, in addition, contains an RNA helicase domain at its C-terminus. NS3 forms a heterodimeric complex with NS4A. The latter is a membrane protein that acts as a cofactor of the proteinase. Although no function has yet been attributed to NS4B, NS5A has been recently suggested to be involved in mediating the resistance of the HCV to the action of interferon. Finally, the NS5B protein has been shown to be the viral RNA-dependent RNA polymerase. This article reviews the current understanding of the structure and the function of the various HCV nonstructural proteins with particular emphasis on their potential as targets for the development of novel antiviral agents and vaccines.
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PMID:Biochemical and immunologic properties of the nonstructural proteins of the hepatitis C virus: implications for development of antiviral agents and vaccines. 1089 33

We previously described autoantibodies against a UGA serine tRNA-protein complex (tRNP(Ser)Sec) in patients with type-1 autoimmune hepatitis [1] and now define the specificity and frequency of this autoantibody and the DNA sequence encoding the tRNA(Ser)Sec-associated antigenic protein. The presence of anti-tRNP(Ser)Sec antibodies was highly specific for type-1 autoimmune hepatitis, as 47.5% of patients were positive compared with none of the control subjects. To characterize the antigenic protein(s), we immunoscreened a human cDNA library with anti-tRNP(Ser)Sec-positive sera. Two clones (19 and 13) were isolated. Clone 19 encodes a protein with a predicted molecular mass of 48.8 kD. Clone 13 is a shorter cDNA, almost identical to clone 19, which encodes a 35.9-kD protein. Expression of both cDNAs was accomplished in Escherichia coli as His-tagged recombinant proteins. Antibodies eluted from both purified recombinant proteins were able to immunoprecipitate the tRNA(Ser)Sec from a HeLa S3 cell extract, demonstrating their cross-reactivity with the mammalian antigenic complex. Recent cloning data relating to the target antigen(s) of autoantibodies in autoimmune hepatitis patients that react with a soluble liver antigen (SLA) and a liver-pancreas antigen (LP) have revealed that these two autoantibodies are identical and that the cloned antigen shows 99% amino acid sequence homology with tRNP(Ser)Sec.
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PMID:Isolation and characterization of cDNA encoding the antigenic protein of the human tRNP(Ser)Sec complex recognized by autoantibodies from patients withtype-1 autoimmune hepatitis. 1093 Nov 55

To better understand the role of beta-catenin mutation in hepatocellular carcinoma (HCC), we correlated the gene mutation with hepatitis virus B (HBV) and hepatitis virus C (HCV) status and the clinicopathological features in 366 patients with resected primary unifocal HCC. beta-Catenin mutations were also analyzed in 55 patients with multifocal HCC (68 tumors). Of the whole series, 57 (13.1%) of 434 tumors examined had beta-catenin mutations, 34 occurred at the serine/threonine residues of the GSK-3beta region of beta-catenin. Outside the GSK-3beta phosphorylation site, codons 32 and 34 were two mutational hot spots (17 tumors). The non-HBV-related HCC that was predominantly HCV related had a higher frequency of mutation (P: < 0.00001) and more frequent mutations at codon 45 than HBV-related HCC. HBV-related HCC had a younger mean age (P: < 0.00001), and higher male-to-female ratio (P: < 0.003) and positive familial history of HCC (P: < 0.014). Among 366 unifocal HCCs selected for clinicopathological analysis, beta-catenin mutations were associated with grade I (P: = 0.005) and stage I and II HCC (P: < 0.0001), and a better 5-year survival rate (P: = 0. 00003). These findings suggest mechanisms for beta-catenin mutations differ between HBV-related and non-HBV-related HCCs, and that beta-catenin mutation is a favorable prognostic factor related to low stage. beta-Catenin mutation was associated with nuclear expression of the protein (P: < 0.00001), but we failed to detect point or large fragment deletion mutation in 39 HCCs with nuclear beta-catenin expression, presumably wild-type protein. HCCs expressing mutant nuclear beta-catenin had a better 5-year survival rate (P: < 0.007), suggesting that mutant and wild-type nuclear beta-catenin proteins are not functionally equivalent and deserve more studies for further clarification.
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PMID:Beta-catenin mutations are associated with a subset of low-stage hepatocellular carcinoma negative for hepatitis B virus and with favorable prognosis. 1098 Jan 16


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