Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.1.27.1 (RNase)
 16,360 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Although a number of recent studies have suggested that the function of the hepatitis C virus (HCV) core protein may be both to package the viral genome and to modulate host cellular processes, little is known of the structure of the core protein necessary to accomplish these functions. Using in vitro assembled particles that mimic essential features of native HCV nucleocapsids, we report the earliest structural information of the HCV core protein and its nucleocapsid. The core protein is proteinase-resistant when assembled into nucleocapsid-like particles or complexed with nucleic acid in vitro. In contrast, the highly basic amino terminus of the free core protein is sensitive to proteolytic digestion. The hydrophobic carboxyl-terminal region of the core protein stabilizes the structure of the free core protein but is not required to stabilize core protein assembled into nucleocapsid-like particles or complexed to nucleic acid. Significantly, the carboxyl-terminal region is sufficient, but not necessary, to fold the core protein into a stable structure. These data are consistent with a model of a partially flexible HCV core protein that undergoes extensive conformational changes upon binding to nucleic acid and assembling into nucleocapsid particles. In addition, the susceptibility of nucleocapsid particles to RNase digestion suggests that RNA-core interactions may stabilize HCV nucleocapsids.
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PMID:Conformational changes accompanying self-assembly of the hepatitis C virus core protein. 1200 65

Previous studies indicated that hepatitis C virus core protein influences cellular apoptosis. However, the precise mechanisms of the effects are not fully understood. Therefore, in this study, we examined the mechanisms of the effects on cell apoptosis by core protein, using transiently transfected and magnetically collected core-producing HepG2 cells. First, to elucidate the target site of core protein in the apoptotic pathway, we examined the activation of caspases after anti-Fas antibody stimulation. Core protein inhibited the apoptotic cascade downstream from caspase 8 and upstream from caspase 3. Next, to clarify more direct mechanisms of this effect, mRNA levels of several bcl-2-related genes were examined. An RNase protection assay showed that the mRNA of bcl-xl increased in the core-producing cells. We showed that this increase was mediated by the enhancement of bcl-x promoter activity by core protein through an extracellular-regulated kinase pathway. These results suggest that core protein inhibits apoptosis at the mitochondria level through augmentation of Bcl-x expression, resulting in an inhibition of caspase 3 activation.
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PMID:Hepatitis C virus core protein inhibits apoptosis via enhanced Bcl-xL expression. 1203 20

Hepatitis C virus (HCV) replicates in salivary glands of chronic hepatitis C patients and is released into the saliva, suggesting that HCV may replicate in other exocrine glands. The presence of positive and negative HCV RNA strands was demonstrated by in situ hybridization, and of HCV core protein by immunohistochemistry, in sweat glands and keratinocytes in healthy skin biopsies from 15 patients with chronic hepatitis C and 10 anti-HCV negative patients with chronic liver disease. Positive and negative HCV RNA strands were detected in 9.6 +/- 5.2% and 4.2 +/- 3.8%, respectively, of the epithelial cells of eccrine sweat glands. Core protein was detected in 6.0 +/- 3.93% of these cells. HCV RNA resistant to RNase digestion (encapsidated HCV RNA) was detected in 10/10 sweat samples from HCV-infected patients. Positive and negative HCV RNA strands were detected in 6.7 +/- 2.97% and 3.0 +/- 3.08% of the keratinocytes, respectively. HCV core protein was found in 4.5 +/- 2.76% of these cells. No HCV RNA or HCV core protein was detected in the skin biopsies from the 10 anti-HCV negative patients. In conclusion, HCV replicates in eccrine sweat glands cells and keratinocytes in healthy skin and is released into the sweat.
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PMID:Hepatitis C virus replicates in sweat glands and is released into sweat in patients with chronic hepatitis C. 1237 61

The syndecan family of heparan sulfate proteoglycans participates in cellular activation through interactions with growth factors, extracellular matrix, and other molecules. The family consists of four proteins that share sequence homology within their cytosolic domains. Here we report that a 5.8 kb region of human chromosome 22q12.2 contains multiple segments that share greater than 80% sequence homology to the syndecan 4 transcript, including homology to 443 nucleotides of the syndecan 4 coding region. Three pieces of evidence indicate that the chromosome 22 sequences are a syndecan 4 pseudogene. First, single nucleotide gaps need to be inserted into the chromosome 22 sequence in order to maintain maximal alignment to the syndecan 4 coding sequence, and this introduces stop codons into a deduced amino acid sequence. Second, the total length of chromosome 22 containing the homologous sequences is compressed when compared to the genomic organization of the complementary syndecan 4 sequences. Third, the 5.8 kb chromosome 22 sequence contains multiple Alu and other repetitive sequences, and this is a property of pseudogenes. Both RT-PCR and RNase protection assays indicated that the syndecan 4 pseudogene is transcribed in human umbilical vein endothelial cells.
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PMID:Identification of a syndecan 4 pseudogene. 1265 6

The majority of persons with chronic hepatitis C virus (HCV) infection develop liver fibrosis. Transforming growth factor (TGF)-beta 1 plays a pivotal role in the pathogenesis of post-inflammatory liver scarring. To clarify the influence of HCV infection on liver fibrosis, a reporter assay was used to investigate the effect of viral proteins on TGF-beta 1 expression in human hepatoma cells. Of all HCV proteins investigated (core, E1/E2/p7, NS2, NS3, NS4A, NS4B, NS5A, and NS5B), only the core protein activated the TGF-beta 1 promoter and upregulated TGF-beta 1 expression measured by an RNase protection assay. Bases -376 to -331 bp in the promoter region of TGF-beta 1 are responsible for upregulation by HCV core protein, and the nuclear protein that binds to this region increased with the stimulation of HCV core protein. Blocking the mitogen-activated protein kinase pathway prevented upregulation of TGF-beta 1 by HCV core protein. The immunological response is supposed to be a major factor to cause the secretion of TGF-beta 1 from non-parenchymal cells, but the results suggest that the HCV core protein expression may upregulate directly TGF-beta 1 transcription in parenchymal cells and suggest a new paradigm for exacerbation of liver fibrosis by HCV infection.
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PMID:Hepatitis C virus core protein upregulates transforming growth factor-beta 1 transcription. 1463 11

HepG2 cells stably transfected with a full-length, infectious hepatitis C virus (HCV) cDNA demonstrated consistent replication of HCV for more than 3 years. Intracellular minus strand HCV RNA was present. Minus strand synthesis was NS5B dependent, and was sensitive to interferon alpha (IFN alpha) treatment. NS5B and HCV core protein were detectable. HCV stimulated HepG2 cell growth and survival in culture, in soft agar, and accelerated tumor growth in SCID mice. These mice became HCV RNA positive in blood, where the virus was also sensitive to IFN alpha. The RNA banded at the density of HCV, and was resistant to RNase prior to extraction. Hence, HCV stably replicates in HepG2 cells, stimulates hepatocellular growth and tumorigenesis, and is susceptible to IFN alpha both in vitro and in vivo.
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PMID:Hepatitis C virus replication in stably transfected HepG2 cells promotes hepatocellular growth and tumorigenesis. 1538 52

The hepatitis C virus (HCV) core protein is involved in the assembly of nucleocapsid particles, as well as regulation of cellular and viral gene expression. To investigate the biological properties of the viral core protein and viral RNA assembly, two recombinant core proteins, the mature core protein (named C179) and a C-terminal truncated protein (named C124), were expressed and purified. To confirm their ability to generate viral particles, the production of nucleocapsid-like particles was monitored using transmission electron microscopy (EM). The EM analysis revealed that exposure of these proteins to the 5' untranslated region (5' UTR) of the viral RNA resulted in generation of spherical particles of 30-140nm in diameter. Interestingly, a cross-linking analysis revealed that C124 required an RNA component for homotypic interactions. In contrast, C179 successfully assembled in the absence of nucleic acids. Additionally, RNA-mediated conversion of the C124 structure into a more stable state was maintained even after RNase treatment. Therefore, our results indicate that the basic N-terminal domain of the viral core protein utilizes RNA components to induce conformational changes or efficient homotypic interactions, while the C-terminal domain may contain key peptide sequences for initiating spontaneous multimerization at the early stages of viral assembly.
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PMID:Structural requirements for assembly and homotypic interactions of the hepatitis C virus core protein. 1694 99

RNA silencing is a form of nucleic acid-based immunity against viruses in plants and invertebrate animals. Successful viral infection requires evasion or suppression of gene silencing. Here, we report that the core protein of Hepatitis C virus (HCV) acts as a potent suppressor of RNA silencing (SRS). We have found that the HCV core protein inhibits RNA silencing induced by short hairpin RNAs (shRNAs) but not by synthetic small interfering RNAs (siRNAs) in various mammalian cells. We have further demonstrated that HCV core protein directly interacts with Dicer, an RNase enzyme that generates siRNA in host cells. The HCV core protein has been shown to inhibit the function of Dicer to process double-stranded RNAs (dsRNAs) into siRNAs. Through deletion analysis, we have found that the N-terminal domain is required for core protein to antagonize RNA silencing activity of Dicer enzyme. Thus, our results suggest that HCV core protein may abrogate host cell RNA silencing defense by suppressing the ability of Dicer to process precursor dsRNAs into siRNAs. This anti-Dicer ability of core protein may contribute to the persistent viral infection and pathogenesis of HCV.
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PMID:HCV core protein interacts with Dicer to antagonize RNA silencing. 1832 16

Hepatitis B virus (HBV)-targeted ribonuclease (HBV-TR) is a fused protein of HBV core protein and a ribonuclease, human eosinophil-derived neurotoxin (hEDN). Our previous results showed that HBV-TR could effectively inhibit HBV replication in vitro. To test whether HBV-TR can inhibit HBV replication in vivo, we constructed a recombinant adenoviral vector expressing HBV-TR (Ad-TR) and used it to treat HBV-transgenic mice. Immunohistochemical staining showed that TR was expressed at varied levels in different tissues of Ad-TR-treated mice. Serum HBsAg concentration was decreased by 64.8% for the Ad-TR-treated mice compared with empty adenoviral vector-treated control mice. The amount of HBV-DNA in the livers of the Ad-TR-treated mice was 0.74 x 10(7) copies/mug of genomic DNA while the amount of HBV-DNA in the livers of the empty adenoviral vector-treated control mice was 2.86 x 10(7) copies/mug of genomic DNA. Serum HBV-DNA of Ad-TR-treated mice was also decreased by 71.4% compared with empty adenoviral vector-treated control mice. In addition, for some Ad-TR-treated mice, the expression of HBsAg in the liver cells turned negative. No discernible adverse effects were observed for Ad-TR-treated mice. Taken together, our results indicated that adenovirus mediated transfer of HBV-TR can inhibit HBV replication in vivo.
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PMID:Adenoviral-vector mediated transfer of HBV-targeted ribonuclease can inhibit HBV replication in vivo. 1845 8

HBV-targeted ribonuclease (TR) is a fusion of HBV core protein (HBVc) and human eosinophil-derived neurotoxin (hEDN). Introduction of TR by transfection or transduction into HepG2.2.15 cells (a cell model of HBV infection) revealed that it significantly reduces serological markers of HBV replication (including HBsAg, HBeAg and HBV DNA) in cell supernatants, suggesting that the targeted ribonuclease inhibits HBV replication. To further our understanding of the molecular mechanism of the anti-HBV effect of TR, we expressed TR in E. coli and found that purified TR possesses RNase activity and targeting activity. Furthermore, the antiviral effect of TR depends both on an enzymatically active hEDN and on the core domain. In or out of HepG2.2.15 cells, TR coassembles with the wild-type capsid protein into particles with internal hEDN domains. Our data suggest an intracellular ribonuclease activation mechanism that, owing to the characteristics of HBV morphogenesis, is highly virus specific. HBV may therefore be particularly vulnerable to the capsid-targeted viral inactivation approach.
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PMID:A promising alternative anti-HBV agent: the targeted ribonuclease. 2051 22


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