Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0038362 (stomatitis)
 8,852 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

MxA is a GTPase encoded by an interferon-inducible human gene. Its constitutive expression renders transfected mammalian cells resistant to infections with several different RNA viruses, including vesicular stomatitis virus (VSV). Differences in viral RNA levels of VSV-infected cells either expressing or lacking MxA indicated that VSV mRNA synthesis is the principal target of MxA action. We now used purified histidine-tagged MxA (His-MxA) that we produced in Escherichia coli to successfully inhibit VSV in vitro transcription, a reaction catalyzed by VSV ribonucleoprotein complexes isolated from virus-infected cells or from purified virions. MxA was inactive when added to preformed VSV mRNAs, arguing against the possibility that it has a negative effect on viral RNA stability. MxA inhibited both leader RNA and mRNA synthesis of VSV, suggesting that it interfered with transcription initiation. The degree of VSV inhibition correlated directly with the specific GTPase activities of the various wild-type MxA preparations. No inhibition of viral mRNA synthesis was observed when a C-terminally truncated, GTPase-inactive variant of His-MxA was added to the transcription reactions. Purified His-MxA-E645R, a mutant of MxA with normal GTPase activity whose range of antiviral activity in vivo is altered so that it no longer inhibits VSV, showed no inhibitory effect on VSV in vitro transcription. Since MxA inhibited VSV RNA synthesis in the presence of GMP-PNP or GTP gamma S, GTP analogs that are readily accepted by the viral polymerase but cannot be hydrolyzed by MxA, the possibility was excluded that MxA acts by depleting the viral polymerase for its nucleotide substrates. Thus, binding of GTP rather than its hydrolysis seems of importance for the anti-VSV activity of MxA.
 ...
PMID:Vesicular stomatitis virus transcription inhibited by purified MxA protein. 783 9

Protein kinase activities associated with a highly purified transcriptionally active ribonucleoprotein complex from the virions of vesicular stomatitis virus (VSV) were isolated and characterized. Based upon several biochemical and immunological criteria, the protein kinase activity, which phosphorylated the bacterially expressed unphosphorylated (Po) protein, was shown to be cellular casein kinase II (CKII). These studies included inhibition of the protein kinase by specific inhibitors, phosphorylation of mutant phosphoproteins (P), immunoprecipitation by CKII antibody and Western blot analyses, and finally its ability to activate Po to synthesize RNA in a transcription-reconstitution reaction. The P protein is phosphorylated intracellularly by cellular CKII. The present study demonstrates that VSV specifically packages CKII which remains strongly associated with the ribonucleoprotein complex during morphogenesis.
 ...
PMID:Casein kinase II is the P protein phosphorylating cellular kinase associated with the ribonucleoprotein complex of purified vesicular stomatitis virus. 784 56

Recently, the vesicular stomatitis virus matrix (M) protein has been shown to be capable of inhibition of host cell-directed transcription in the absence of other viral components (B. L. Black and D. S. Lyles, J. Virol. 66:4058-4064, 1992). M protein is a major structural protein that is known to play a critical role in virus assembly by binding the helical ribonucleoprotein core of the virus to the cytoplasmic surface of the cell plasma membrane during budding. In this study, two M protein mutants were tested to determine whether the inhibition of host transcription by M protein is an indirect effect of its function in virus assembly or whether it represents an independent function of M protein. The mutant M protein of the conditionally temperature-sensitive (ts) vesicular stomatitis virus mutant, tsO82, was found to be defective in its ability to inhibit host-directed gene expression, as shown by its inability to inhibit expression of a cotransfected target gene encoding chloramphenicol acetyltransferase. The ability of the tsO82 M protein to function in virus assembly was similar to that of wild-type M protein, as shown by its ability to complement the group III ts M protein mutant, tsO23. Another mutant, MN1, which lacks amino acids 4 to 21 of M protein demonstrated that the abilities of M protein to inhibit chloramphenicol acetyltransferase gene expression and to localize to the nucleus were unaffected by deletion of this lysine-rich amino-terminal region but that the ability to function in virus assembly was ablated. Thus, the two M protein mutants examined in this study exhibited complementary phenotypes: tsO82 M protein functioned in virus assembly but was defective in inhibition of host-directed gene expression, while MN1 M protein functioned in inhibiting gene expression but was unable to function in virus assembly. These data demonstrate that the role of M protein in inhibition of host transcription can be separated genetically from its role in virus assembly.
 ...
PMID:The role of vesicular stomatitis virus matrix protein in inhibition of host-directed gene expression is genetically separable from its function in virus assembly. 839 15

The nucleocapsid protein (N) and phosphoprotein (P) genes of vesicular stomatitis virus (VSV), Indiana serotype, were coexpressed in Escherichia coli BL21(DE3) by using the expression vector pET-3a. The coexpression resulted in the formation of N-P complex. The purified N-P complex was found to inhibit transcription in vitro mediated by viral ribonucleoprotein (RNP) complex in a dose-dependent manner. However, addition of uninfected mammalian cell extracts together with the N-P complex to the transcribing RNP resulted in the synthesis of full-length negative-strand genome RNA. These results indicate that the N-P complex regulated transcription and a cellular factor(s) in combination with the N-P complex may switch the RNA polymerase from transcription to replication mode.
 ...
PMID:Expression and purification of vesicular stomatitis virus N-P complex from Escherichia coli: role in genome RNA transcription and replication in vitro. 915 13

The nucleoprotein (NP) and matrix protein (M1) are the most abundant structural proteins of influenza A virus. M1 forms a protein layer beneath the viral envelope and NP constitutes the protein backbone of the ribonucleoproteins (RNPs). In order to elucidate the functions of these proteins in virus assembly we have expressed NP and M1 in BHK-21 cells using Semliki Forest virus replicons and analysed their molecular interactions. We found that both M1 and NP engaged in extensive homooligomerization reactions soon after synthesis. However, there was no detectable heterooligomerization taking place between the two viral proteins, nor between these and host proteins. One interpretation of these results is that homooligomers, and not monomers, of NP and M1 are used as building blocks during RNP assembly and formation of the submembranous M1 layer, respectively. The complete absence of M1-NP heterooligomers suggests, on the other hand, that these two major viral proteins do not interact directly with each other during virus assembly. We also found that a fraction of M1 associated with cellular membranes. This did not, however, result in membrane budding or vesicularization as was the case with the matrix protein of vesicular stomatitis virus when expressed separately (P. A. Justice and others, Journal of Virology 69, 3156-3160, 1995).
 ...
PMID:The M1 and NP proteins of influenza A virus form homo- but not heterooligomeric complexes when coexpressed in BHK-21 cells. 978 49

The major vault protein (MVP) is the predominant constituent of ubiquitous, evolutionarily conserved large cytoplasmic ribonucleoprotein particles of unknown function. Vaults are multimeric protein complexes with several copies of an untranslated RNA. Double labeling employing laser-assisted confocal microscopy and indirect immunofluorescence demonstrates partial colocalization of vaults with cytoskeletal elements in Chinese hamster ovary (CHO) and nerve growth factor (NGF)-treated neuronlike PC12 cells. Transfection of CHO and PC12 cells with a cDNA encoding the rat major vault protein containing a vesicular stomatitis virus glycoprotein epitope tag demonstrates that the recombinant protein is sorted into vault particles and targeted like endogenous MVPs. In neuritic extensions of differentiated PC12 cells, there is an almost complete overlap of the distribution of microtubules and vaults. A pronounced colocalization of vaults with filamentous actin can be seen in the tips of neurites. Moreover, in NGF-treated PC12 cells the location of vaults partially coincides with vesicular markers. Within the terminal tips of neurites vaults are located near secretory organelles. Our observations suggest that the vault particles are transported along cytoskeletal-based cellular tracks.
 ...
PMID:Recombinant major vault protein is targeted to neuritic tips of PC12 cells. 1008 61

The eukaryotic nucleolus contains a large number of small RNA molecules that, in the form of small nucleolar ribonucleoprotein complexes (snoRNPs), are involved in the processing and modification of pre-rRNA. One of the snoRNPs that has been shown to possess enzymatic activity is the RNase MRP. RNase MRP is an endoribonuclease involved in the formation of the 5' end of 5.8S rRNA. In this study the association of the hPop1 protein with the RNase MRP complex was investigated. The hPop1 protein seems not to be directly bound to the RNA component, but requires nt 1-86 and 116-176 of the MRP RNA to associate with the RNase MRP complex via protein-protein interactions. UV crosslinking followed by ribonuclease treatment and immunoprecipitation with anti-Th/To antibodies revealed three human proteins of about 20, 25, and 40 kDa that can associate with the RNase MRP complex. The 20- and 25-kDa proteins appear to bind to stem-loop I of the MRP RNA whereas the 40-kDa protein requires the central part of the MRP RNA (nt 86-176) for association with the RNase MRP complex. In addition, we show that the human RNase P proteins Rpp30 and Rpp38 are also associated with the RNase MRP complex. Expression of Vesicular Stomatitis Virus- (VSV) tagged versions of these proteins in HeLa cells followed by anti-VSV immunoprecipitation resulted in coprecipitation of both RNase P and RNase MRP complexes. Furthermore, UV crosslinking followed by anti-Th/To and anti-Rpp38 immunoprecipitation revealed that the 40-kDa protein we detected in UV crosslinking is probably identical to Rpp38.
 ...
PMID:RNA-protein interactions in the human RNase MRP ribonucleoprotein complex. 1019 68

Enveloped viruses often enter cells via endocytosis; however, specific endocytic trafficking pathway(s) for many viruses have not been determined. Here we demonstrate, through the use of dominant-negative Rab5 and Rab7, that influenza virus (Influenza A/WSN/33 (H1N1) and A/X-31 (H3N2)) requires both early and late endosomes for entry and subsequent infection in HeLa cells. Time-course experiments, monitoring viral ribonucleoprotein colocalization with endosomal markers, indicated that influenza exhibits a conventional endocytic uptake pattern--reaching early endosomes after approximately 10 min, and late endosomes after 40 min. Detection with conformation-specific hemagglutinin antibodies indicated that hemagglutinin did not reach a fusion-competent form until the virus had trafficked beyond early endosomes. We also examined two other enveloped viruses that are also pH-dependent for entry--Semliki Forest virus and vesicular stomatitis virus. In contrast to influenza virus, infection with both Semliki Forest virus and vesicular stomatitis virus was inhibited only by the expression of dominant negative Rab5 and not by dominant negative Rab7, indicating an independence of late endosome function for infection by these viruses. As a whole, these data provide a definitive characterization of influenza virus endocytic trafficking and show differential requirements for endocytic trafficking between pH-dependent enveloped viruses.
 ...
PMID:Differential requirements of Rab5 and Rab7 for endocytosis of influenza and other enveloped viruses. 1271 61

Mounting an immune response to a viral pathogen involves the initial recognition of viral antigens through Toll-like receptor-dependent and -independent pathways and the subsequent triggering of signal transduction cascades. Among the many cellular kinases stimulated in response to virus infection, the noncanonical IKK-related kinases TBK1 and IKKepsilon have been shown to phosphorylate and activate interferon regulatory factor 3 (IRF-3) and IRF-7, leading to the production of alpha/beta interferons and the development of a cellular antiviral state. In the present study, we examine the activation of TBK1 and IKKepsilon kinases by vesicular stomatitis virus (VSV) infection in human lung epithelial A549 cells. We demonstrate that replication-competent VSV is required to induce activation of the IKK-related kinases and provide evidence that ribonucleoprotein (RNP) complex of VSV generated intracellularly during virus replication can activate TBK1 and IKKepsilon activity. In TBK1-deficient cells, IRF-3 and IRF-7 activation is significantly reduced, although transcriptional upregulation of IKKepsilon following treatment with VSV, double-stranded RNA, or RNP partially compensates for the loss of TBK1. Biochemical analyses with purified TBK1 and IKKepsilon kinases in vitro demonstrate that the two kinases exhibit similar specificities with respect to IRF-3 and IRF-7 substrates and both kinases target serine residues that are important for full transcriptional activation of IRF-3 and IRF-7. These data suggest that intracellular RNP formation contributes to the early recognition of VSV infection, activates the catalytic activity of TBK1, and induces transcriptional upregulation of IKKepsilon in epithelial cells. Induction of IKKepsilon potentially functions as a component of the amplification mechanism involved in the establishment of the antiviral state.
 ...
PMID:Activation of TBK1 and IKKvarepsilon kinases by vesicular stomatitis virus infection and the role of viral ribonucleoprotein in the development of interferon antiviral immunity. 1536 31

The RNA genome of non-segmented negative-strand RNA viruses is completely covered by the nucleoprotein (N) forming a ribonucleoprotein complex, the nucleocapsid. The nucleocapsid functions as the template for viral RNA synthesis that is mediated by a viral RNA-dependent RNA polymerase. It is postulated that the selection of molecules that would specifically target the nucleocapsid and thus inhibit the viral polymerase activity could represent a common approach to block negative-strand RNA viruses. Two single-chain antibody fragments (scFv) that were selected using the phage display technology and interacted specifically with vesicular stomatitis virus (VSV) nucleocapsid were characterized. The two recombinant antibodies recognize a conformational epitope on the nucleocapsid and immunoprecipitate specifically nucleocapsids from infected cell extracts. Both antibodies have a strong inhibitory effect on VSV transcription activity in vitro. Thus, they represent starting molecules for future development of in vivo viral RNA synthesis inhibitors.
 ...
PMID:Selection of single-chain antibodies that specifically interact with vesicular stomatitis virus (VSV) nucleocapsid and inhibit viral RNA synthesis. 1607 1


<< Previous 1 2 3 4 5 6 7 8 Next >>