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)

Brefeldin A (BFA) was shown in earlier studies of numerous cell types to inhibit secretion, induce enzymes of the Golgi stacks to redistribute into the ER, and to cause the Golgi cisternae to disappear. Here, we demonstrate that the PtK1 line of rat kangaroo kidney cells is resistant to BFA. The drug did not disrupt the morphology of the Golgi complex in PtK1 cells, as judged by immunofluorescence using antibodies to 58- (58K) and 110-kD (beta-COP) Golgi proteins, and by fluorescence microscopy of live cells labeled with C6-NBD-ceramide. In addition, BFA did not inhibit protein secretion, not alter the kinetics or extent of glycosylation of the vesicular stomatitis virus (VSV) glycoprotein (G-protein) in VSV-infected PtK1 cells. To explore the mechanism of resistance to BFA, PtK1 cells were fused with BFA-sensitive CV-1 cells that had been infected with a recombinant SV-40 strain containing the gene for VSV G-protein and, at various times following fusion, the cultures were exposed to BFA. Shortly after cell fusion, heterokaryons contained one Golgi complex associated with each nucleus. Golgi membranes derived from CV-1 cells were sensitive to BFA, whereas those of PtK1 origin were BFA resistant. A few hours after fusion, most heterokaryons contained a single, large Golgi apparatus that was resistant to BFA and contained CV-1 galactosyltransferase. In unfused cells that had been perforated using nitrocellulose filters, retention of beta-COP on the Golgi was optimal in the presence of cytosol, ATP, and GTP. In perforated cell models of the BFA-sensitive MA104 line, BFA caused beta-COP to be released from the Golgi complex in the presence of nucleotides, and either MA104 or PtK1 cytosol. In contrast, when perforated PtK1 cells were incubated with BFA, nucleotides, and cytosol from either cell type, beta-COP remained bound to the Golgi complex. We conclude that PtK1 cells contain a nondiffusible factor, which is located on or very close to the Golgi complex, and confers a dominant resistance to BFA. It is possible that this factor is homologous to the target of BFA in cells that are sensitive to the drug.
 ...
PMID:PtK1 cells contain a nondiffusible, dominant factor that makes the Golgi apparatus resistant to brefeldin A. 171 Feb 24

Regulated exocytosis in many permeabilized cells can be triggered by calcium and nonhydrolyzable GTP analogues. Here we examine the role of these effectors in exocytosis of constitutive vesicles using a system that reconstitutes transport between the trans-Golgi region and the plasma membrane. Transport is assayed by two independent methods: the movement of a transmembrane glycoprotein (vesicular stomatitis virus glycoprotein [VSV G protein]) to the cell surface; and the release of a soluble marker, sulfated glycosaminoglycan (GAG) chains, that have been synthesized and radiolabeled in the trans-Golgi. The plasma membrane of CHO cells was selectively perforated with the bacterial cytolysin streptolysin-O. These perforated cells allow exchange of ions and cytosolic proteins but retain intracellular organelles and transport vesicles. Incubation of the semi-intact cells with ATP and a cytosolic fraction results in transport of VSV G protein and GAG chains to the cell surface. The transport reaction is temperature dependent, requires hydrolyzable ATP, and is inhibited by N-ethylmaleimide. Nonhydrolyzable GTP analogs such as GTP gamma S, which stimulate the fusion of regulated secretory granules, completely abolish constitutive secretion. The rate and extent of constitutive transport between the trans-Golgi and the plasma membrane is independent of free Ca2+ concentrations. This is in marked contrast to fusion of regulated secretory granules with the plasma membrane, and transport between the ER and the cis-Golgi (Beckers, C. J. M., and W. E. Balch. 1989. J. Cell Biol. 108:1245-1256; Baker, D., L. Wuestehube, R. Schekman, and D. Botstein. 1990. Proc. Natl. Acad. Sci. USA. 87:355-359).
 ...
PMID:Reconstitution of constitutive secretion using semi-intact cells: regulation by GTP but not calcium. 198 6

(+/-)-6' beta-Fluoroaristeromycin (F-C-Ado) is a potent and competitive inhibitor of purified S-adenosylhomocysteine (AdoHcy) hydrolase isolated from murine L929 cells (Ki = 3.1 nM). It also inhibits vaccinia virus and vesicular stomatitis virus replication in L929 cells, at a 90% inhibitory dose (ID90) of 3.5 and 13 microM, respectively. Considering the close correlation that has been found between Ki and ID90 for other AdoHcy hydrolase inhibitors [Biochem. Pharmacol. 38:1061-1067 (1989)], F-C-Ado is a weaker antiviral agent than expected from its Ki value. Nevertheless, the antiviral action of F-C-Ado appears to be targeted at AdoHcy hydrolase. The fact that F-C-Ado is less antivirally active than expected may be due to its further metabolism to its ATP and GTP derivatives. The cytotoxicity of F-C-Ado may be attributed to both its inhibitory effect on AdoHcy hydrolase and the inhibitory effect of its phosphorylated products on host cell RNA synthesis.
 ...
PMID:Mechanism of antiviral and cytotoxic action of (+/-)-6' beta-fluoroaristeromycin, a potent inhibitor of S-adenosylhomocysteine hydrolase. 205 90

The diadenylate triphosphates ppp5'A2'p5'A and ppp5'A3'p5'A were found to inhibit the purified RNA polymerase ('nucleocapsid') complex from vesicular stomatitis virus (VSV). The corresponding diadenylate monophosphate p5'A2'p5'A did not inhibit, nor did the triadenylate triphosphate ppp5'A2'p5'A2'p5'A; the diadenylate diphosphate pp5'A2'p5'A had intermediate inhibitory activity. Increasing the concentration of ATP, GTP or CTP in the reaction mixture decreased inhibition by ppp5'A2'p5'A, while UTP had minimal or no protective effect. ppp5'A2'p5'A did not protect the RNA polymerase from inactivation by N-ethylmaleimide. This suggests that the action of ppp5'A2'p5'A occurs at a site on the enzyme that is distinct from the N-ethylmaleimide-protecting, ATP-binding site characterized previously.
 ...
PMID:Inhibition of the RNA polymerase of vesicular stomatitis virus by ppp5'A2'p5'A and related compounds. 216 Jul 97

Immunoisolation techniques have led to the purification of apical and basolateral transport vesicles that mediate the delivery of proteins from the trans-Golgi network to the two plasma membrane domains of MDCK cells. We showed previously that these transport vesicles can be formed and released in the presence of ATP from mechanically perforated cells (Bennett, M. K., A. Wandinger-Ness, and K. Simons, 1988. EMBO (Euro. Mol. Biol. Organ.) J. 7:4075-4085). Using virally infected cells, we have monitored the purification of the trans-Golgi derived vesicles by following influenza hemagglutinin or vesicular stomatitis virus (VSV) G protein as apical and basolateral markers, respectively. Equilibrium density gradient centrifugation revealed that hemagglutinin containing vesicles had a slightly lower density than those containing VSV-G protein, indicating that the two fractions were distinct. Antibodies directed against the cytoplasmically exposed domains of the viral spike glycoproteins permitted the resolution of apical and basolateral vesicle fractions. The immunoisolated vesicles contained a subset of the proteins present in the starting fraction. Many of the proteins were sialylated as expected for proteins existing the trans-Golgi network. The two populations of vesicles contained a number of proteins in common, as well as components which were enriched up to 38-fold in one fraction relative to the other. Among the unique components, a number of transmembrane proteins could be identified using Triton X-114 phase partitioning. This work provides evidence that two distinct classes of vesicles are responsible for apical and basolateral protein delivery. Common protein components are suggested to be involved in vesicle budding and fusion steps, while unique components may be required for specific recognition events such as those involved in protein sorting and vesicle targeting.
 ...
PMID:Distinct transport vesicles mediate the delivery of plasma membrane proteins to the apical and basolateral domains of MDCK cells. 220 40

A biochemical basis for the pea and lentil lectin resistance of two Chinese hamster ovary (CHO) cell mutants, Lec13 and Lec13A, was investigated. Studies of the G glycopeptides of vesicular stomatitis virus grown in the mutants indicated that Lec13 cells essentially lack the ability to add fucose to complex carbohydrates while Lec13A cells synthesize significant proportions of fucosylated, complex moieties. However, both mutants were known to be reverted to lectin sensitivity by growth in L-fucose, making them similar to the mouse lymphoma mutant, PLR1.3, which is defective in the conversion of GDP-mannose to GPD-fucose [M. L. Reitman, I. S. Trowbridge, and S. Kornfeld (1980) J. Biol. Chem. 255, 9900-9906]. Optimal conditions for the production of GDP-fucose from GDP-mannose by CHO cytosol were found to occur at pH 8 in the presence of 7.5 microM GDP-mannose, 15 mM Mg2+, 0.2 mM NAD+, 0.2 mM NADPH, 10 mM niacinamide, 5 mM ATP, and 50 mM Tris-HCl. Under these conditions, Lec13 cytosol produced no detectable GDP-fucose nor GDP-sugar intermediates while Lec13A cytosol produced significant quantities of both. Mixing experiments with Lec13 cytosol identified the first enzyme of the conversion pathway (GDP-mannose 4,6-dehydratase, EC 4.2.1.47) as the site of the block. In addition to being markedly reduced, the Lec13A 4,6-dehydratase activity was relatively insensitive to changes in pH in comparison to the activity in parental cytosol, suggesting that Lec13A cells might possess a structurally altered GDP-mannose 4,6-dehydratase enzyme.
 ...
PMID:Two Chinese hamster ovary glycosylation mutants affected in the conversion of GDP-mannose to GDP-fucose. 242 10

Cleavage of the beta-gamma bond of ATP is required for wild-type (wt) vesicular stomatitis virus transcription in vitro. Recent findings have established that a domain-specific phosphorylation of the virus NS protein is necessary for activity. We report here that RNA synthesis catalyzed by purified standard wt virions responded cooperatively to various ATP concentrations, with half-maximal activity at approximately 500 microM. In contrast, mutant polR1 standard virions and wt defective interfering particles both showed conventional Michaelis-Menten kinetic profiles with Km values of approximately 143 and approximately 133 microM, respectively. The former synthesize readthrough products of the leader-N gene junction in addition to plus-strand leader RNA and mRNAs, whereas the latter synthesize only minus-strand leader RNA. The cooperative response of wt virus products, however, was specific to mRNAs; the small fraction of the total products corresponding to plus-strand leader approximated Michaelis-Menten behavior. Since the unique phenotype of the polR mutants correlates with the synthesis of replicationlike products in vitro, the affected ATP-requiring function most likely regulates both transcription and replication. We suggest that this mutated function involves phosphorylation of viral proteins.
 ...
PMID:Differential effect of ATP concentration on synthesis of vesicular stomatitis virus leader RNAs and mRNAs. 244 17

We have studied the effect of phosphorylated ribavirin on the vesicular stomatitis virus (VSV) in vitro polymerase reaction by analysis of kinetic data obtained by varying the concentration of nucleoside triphosphates. The wild-type VSV had previously shown a competitive inhibition with the four natural nucleoside triphosphates with the use of ribavirin diphosphate (RDP) or ribavirin triphosphate (RTP). In contrast, when RDP (or RTP) was added to a transcription assay system using the polR1 mutant of VSV, a non-competitive or mixed type of inhibition was observed when the concentration of ATP was varied. Our results indicate that polR1 has an altered ATP function in addition to the previously described phenotypic characteristics of this mutant, which include synthesis of readthrough products of the leader/nucleocapsid (N) gene junction and a decreased ATP requirement for transcription. We have also studied CsCl-purified in vitro transcription products by primer-extending leader or N mRNA transcripts and found that the ratio of leader/N mRNA for VSV polR1 (1.3:1) was lower than values obtained previously for wild-type (3.7:1).
 ...
PMID:Altered ATP function of a vesicular stomatitis virus mutant detected by kinetic analysis of the transcriptase using phosphorylated ribavirin. 255 7

The effect of phosphorylated ribavirin on the vesicular stomatitis virus in vitro transcription reaction was examined. Analysis of the kinetics observed when the concentrations of nucleoside triphosphates were varied was performed with vesicular stomatitis virus wild-type standard virions. Double-reciprocal and Eadie-Hofstee plots showed competitive inhibition with all natural nucleoside triphosphates when both ribavirin diphosphate (RDP) and ribavirin triphosphate (RTP) were used. The Km values for ATP obtained for the wild-type polymerase were similar to those reported previously. To further characterize the observed inhibition kinetics, in vitro transcription products synthesized in the presence or absence of RDP and RTP were purified by CsCl centrifugation and were primer extended with oligonucleotides specific for either positive-sense leader or nucleocapsid mRNA transcripts. The ratios of leader to nucleocapsid mRNA were measured from primer-extended in vitro transcription products. It was found that the addition of RDP or RTP did not significantly change the in vitro ratio, suggesting that the polymerase is blocked before it enters the 3' end of the template.
 ...
PMID:Molecular analysis of the inhibitory effect of phosphorylated ribavirin on the vesicular stomatitis virus in vitro polymerase reaction. 255 73

The appearance of newly synthesized glycoprotein (G) of vesicular stomatitis virus at the surface of infected BHK cells is inhibited reversibly by treatment with carbonylcyanide m-chlorophenylhydrazone (CCCP). Under the conditions used, CCCP treatment depleted the cellular ATP levels by 40-60%, consistent with inhibition of transport at energy-requiring stages. The G protein that accumulates in cells treated with CCCP is heterogeneous. Most of it is larger than the newly synthesized G protein, is acylated with palmitic acid, and is resistant to endoglycosidase H (Endo H). Most of the arrested G protein is also sensitive to digestion with neuraminidase, indicating that it has undergone at least partial sialylation. A minority of G protein accumulates under these conditions in a less-mature form, suggesting its inability to reach the mid-Golgi compartment. The oligosaccharides of this G protein are Endo-H-sensitive and seem to be partly trimmed. Whereas sialylated G protein was arrested intracellularly, fucose-labelled G protein was able to complete its transport to the cell surface, indicating that a late CCCP-sensitive step separates sialylation from fucosylation. These post-translational modifications indicate that G protein can be transported as far as the trans-Golgi in the presence of CCCP and is not merely arrested in the endoplasmic reticulum.
 ...
PMID:Intracellular transport of the glycoprotein of VSV is inhibited by CCCP at a late stage of post-translational processing. 255 59


<< Previous 1 2 3 4 5 6 7 8 9 Next >>