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Query: UMLS:C0038362 (stomatitis)
 8,852 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The retinal pigment epithelium (RPE) is able to perform a variety of functions because of its high degree of plasma membrane polarity. Some aspects of this polarity such as the localization of the majority of Na-K ATPase to the apical membrane distinguish the RPE from kidney cells and most other transporting epithelia. The polarized budding of enveloped viruses such as vesicular stomatitis and influenza from the basolateral and apical membrane, respectively, has been used to study mechanisms underlying the domain-specific sorting of membrane proteins in cultured epithelial cell lines. These processes also serve as a useful index of the degree of polarization in epithelial cell cultures. Viral budding from apical and basolateral RPE membranes was used in this study to determine whether the sorting of viral envelope membrane proteins by the RPE is reversed in polarity from that of kidney cells and, if so, whether this might predict a fundamental difference in membrane protein sorting for RPE. The results clearly indicate that the polarity of viral membrane sorting and subsequent viral budding is the same in RPE as in other polarized epithelial cell lines examined to date.
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PMID:Polarized budding of vesicular stomatitis and influenza virus from cultured human and bovine retinal pigment epithelium. 133 32

The polarity of retinal pigmented epithelia (RPE) from chicken embryos was studied in primary cell culture. Since cultured RPE approximates the morphological polarity of RPE in vivo, we investigated whether this polarity extends to the distribution of plasma membrane proteins that are peculiar to RPE. In contrast to other epithelia, the Na+,K(+)-ATPase of RPE is located in the apical rather than basolateral plasma membrane. To examine this property, we cultured RPE on extracellular matrix-coated filters. Primary cultures were compared to embryonic RPE in situ using electron microscopy and indirect immunofluorescence of frozen sections. The viability and morphology of RPE was improved by using a serum-free medium containing a bovine pituitary extract in conjunction with an extracellular matrix coating derived from Engelbreth-Holm-Swarm tumors. Cultured RPE mimicked the morphology of RPE in vivo with microvilli and junctional complexes on the apical pole and infoldings along the basolateral plasma membrane. Functional tight junctions formed as demonstrated by an EDTA-sensitive, transepithelial electrical resistance, and by the retention of [3H]inulin added to the apical chamber. In 2 hr, only 4-6% of the [3H]inulin crossed the monolayer, compared to 24% in control filters. Despite these features of polarity, the Na+,K(+)-ATPase was detected in both apical and basolateral membranes by immunofluorescence. In embryonic eyes in which the neural retina was removed, the Na+,K(+)-ATPase was confined to the apical membrane. In addition, the polarity of cultured RPE was probed with vesicular stomatitis virus. In contrast to other epithelia, budding virus particles were observed emerging from the apical, as well as basolateral, domain further suggesting the cultured cells were only partially polarized. These data indicate that structural criteria are inadequate to determine if cultured RPE have become polarized in the same manner as the epithelium in vivo.
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PMID:The distribution of Na+,K(+)-ATPase in the retinal pigmented epithelium from chicken embryo is polarized in vivo but not in primary cell culture. 217 Jan 60

Prodigiosin 25-C inhibited the accumulation of 3-(2,4-dinitroanilino)-3'-amino-N-methyldipropylamine and acridine orange in the acidic compartments of baby hamster kidney cells with little perturbation of cellular ATP levels. In rat liver lysosomes, prodigiosin 25-C inhibited the proton pump activity with an IC50 of approximately 30 nM, but did not affect ATPase activity up to 1 microM. It also delayed the transport of vesicular stomatitis virus G protein and induced a drastic swelling of Golgi apparatus and mitochondria. These results indicate that prodigiosin 25-C raises the pH of acidic compartments through inhibition of the proton pump activity of vacuolar type H(+)-ATPase, thereby causing the functional and morphological changes to the Golgi apparatus.
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PMID:Prodigiosin 25-C uncouples vacuolar type H(+)-ATPase, inhibits vacuolar acidification and affects glycoprotein processing. 785 30

Semliki Forest virus (SFV) enters cells by receptor-mediated endocytosis, followed by acidification of endosomes by the action of the vacuolar H(+)-ATPase. Fusion of the viral and the endosomal membrane delivers the viral genome to the cytoplasm. Direct blockade of the vacuolar H(+)-ATPase by the selective inhibitor bafilomycin A1 (BFLA1) prevented the infection of cells by SFV, if the compound was present during the first minutes of infection. Attachment and penetration of virus particles were not the targets of the antibiotic. BFLA1 and the ionophore monensin potently blocked SFV infection even at low pH, indicating that acidic pH is not sufficient for SFV to deliver its genome to the cytoplasm, but the proper functioning of the H(+)-ATPase pump is necessary. Other enveloped RNA-containing viruses, such as vesicular stomatitis virus or influenza virus were also blocked by BFLA1, whereas no effect was observed with Sendai virus, which enters into cells by direct fusion with the plasma membrane. Enveloped DNA-containing viruses, such as herpes-viruses and vaccinia virus, infected the cells even when the vacuolar H(+)-ATPase was inhibited by BFLA1; similar behaviour was observed with poliovirus and adenovirus. Animal virus particles promote the internalization of proteins and other macromolecules during entry. BFLA1 blocked co-entry of the toxin alpha-sarcin when induced by SFV, but not when induced by Sendai virus. The inhibition of the enzyme responsible for acidification of endosomes by means of the potent inhibitor BFLA1 constitutes a selective and powerful tool to analyse the low-pH dependent mechanism(s) during virus entry and will aid in understanding the mechanisms and routes of entry of animal viruses into cells.
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PMID:Involvement of the vacuolar H(+)-ATPase in animal virus entry. 793 Nov 46

Folimycin (concanamycin A) specifically inhibited vacuolar-type ATPase as far as examined. Folimycin blocked excretion of the glycoprotein (G protein) of vesicular stomatitis virus into the medium and, instead, G protein was accumulated intracellularly. The intracellularly accumulated G protein electrophoresed a little faster than mature one. The N-glycan of the G protein was endoglycosidase H-sensitive, and terminal galactose and N-acetylglucosamine were not detected essentially on sequential digestion with exoglycosidases, indicating that processings known to occur in the Golgi apparatus do not take place in the presence of folimycin. The oligosaccharide chain of the G protein was determined to have a composition of Man8GlcNAc2 as analyzed by Bio-Gel P-4 column chromatography and high-performance liquid chromatography following digestion with alpha- and then with beta-mannosidase. Activities of mannosidase I and glycosyltransferases prepared from baby hamster kidney cells were not inhibited as far as examined, indicating that the incompleteness of the N-glycosidic chain in folimycin-treated cells is not caused by inhibition of processing enzymes. Taken together these observations suggest that folimycin blocks the intracellular translocation of G protein before the step of trimming by mannosidase I which is confined to the cis compartment of the Golgi. The intracellular localization of G protein as revealed by fluorescence microscopy was in good accordance with this assumption.
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PMID:Folimycin (concanamycin A), a specific inhibitor of V-ATPase, blocks intracellular translocation of the glycoprotein of vesicular stomatitis virus before arrival to the Golgi apparatus. 824 93

When expressed alone in fibroblasts, approximately 80% of newly made H2b subunits of the human asialoglycoprotein receptor are retained and degraded in the endoplasmic reticulum (ER), whereas about 20% reaches the plasma membrane (1). Thapsigargin, an inhibitor of the ER Ca2+ ATPase, blocks ER folding of the H1 (2) as well as of the H2b subunit, prevents maturation of H2b, and accelerates ER degradation of newly made H2b. The secretory pathway is normal in thapsigargin-treated cells, as monitored by maturation of the vesicular stomatitis virus G protein. The protease inhibitors TLCK and TPCK block the first step in ER degradation of H2, an endoproteolytic cleavage just exoplasmic to the membrane-spanning domain. In protease inhibitor-treated cells, the approximately 80% of H2b that would normally be degraded remains in the ER; as judged by migration on nonreducing SDS-polyacrylamide gel electrophoresis this H2b is improperly folded. Thus, incorrectly folded H2b is normally subjected to ER degradation. In the presence of thapsigargin H2b cannot fold properly and is degraded within the ER. The preferential ER degradation of misfolded or unfolded membrane proteins demonstrated here, functions as a step in ER quality control.
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PMID:Unfolded H2b asialoglycoprotein receptor subunit polypeptides are selectively degraded within the endoplasmic reticulum. 831 99

Rat retinal pigment epithelial (RPE) cells were immortalized by infection with a temperature-sensitive tsA SV40 virus and following cloning and selection for epithelial properties the polarized RPE-J cell line was obtained. At the permissive temperature of 33 degrees C, RPE-J cells behave as an immortalized cell line. When RPE-J cells are grown on nitrocellulose filters coated with a thin layer of Matrigel in the presence of 10(-8) M retinoic acid for 6 days at 33 degrees C and then switched for 33-36 hours to the non-permissive temperature of 40 degrees C, they acquire a differentiated polarized RPE phenotype. Under these growth conditions, RPE-J cells exhibit circumferential staining for the tight-junction protein ZO-1 and acquire a transepithelial resistance of 350 ohms cm2. Morphologically, RPE-J cells exhibit a characteristic RPE morphology with extensive apical microvilli as well as numerous dense bodies including premelanosomes and varied multilamellar structures. Ruthenium red labeling revealed the frequent basal localization of the tight junction. The cells were identified to be of rat RPE origin by their expression of the rat RPE marker RET-PE2 and their ability to phagocytose latex beads. While RPE-J cells are capable of sorting influenza and vesicular stomatitis virus to the apical and basal surfaces, respectively, the Na,K-ATPase is not polarized and the neural cell adhesion molecule, N-CAM, is localized exclusively to the lateral surface. In vivo the apical surface of RPE interacts with the adjacent neural retina and the Na,K-ATPase and N-CAM are both apical; the altered polarity of these two proteins in RPE-J cells may be a consequence of the absence of apical interaction with the neural retina in culture. Previous studies of RPE have been restricted to the use of primary cultures and the RPE-J cell line should prove an excellent model system for the study of the mechanisms determining the characteristic polarity and functions of the retinal pigment epithelium.
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PMID:Immortalization of polarized rat retinal pigment epithelium. 838 96

During the course of screening studies to identify inhibitors of intracellular protein trafficking, we isolated efrapeptins as active principles. These compounds arrested syncytium formation (SF) and cytopathic effect (CPE) in Newcastle disease virus (NDV)- and vesicular stomatitis virus (VSV)-infected BHK cells, respectively, without profoundly affecting glycoprotein synthesis. Efrapeptins blocked cell surface expression of NDV-HN and VSV-G glycoproteins, but did not suppress intoxication by ricin or diphtheria toxin even after prolonged pretreatment. Efrapeptins are inhibitors of F-ATPase, or ATP synthase, but their inhibitory effect on SF and CPE was independent of the amount of intracellular ATP.
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PMID:Efrapeptins block exocytic but not endocytic trafficking of proteins. 888 13

The nonapeptide leucinostatin A (LSA) inhibited syncytium formation without profoundly affecting HN glycoprotein synthesis in Newcastle disease virus (NDV)-infected BHK cells. At similar doses of LSA, cytopathic effect and infectious virus production were suppressed in vesicular stomatitis virus (VSV)-infected BHK cells. Blockade by LSA of cell surface expression of NDV-HN and VSV-G glycoproteins was demonstrated, accompanied by intracellular accumulation of these virus glycoproteins. LSA acts as an inhibitor of mitochondrial F-type H(+)-translocating ATPase, a key enzyme in the generation of ATP, but its action against cell surface expression of virus glycoproteins was independent of the depletion of intracellular ATP. LSA also acts as an ionophore, but its action on intoxication by ricin and diphtheria toxin was different from that of monensin. This novel action of LSA is expected to be useful in investigation of the mechanism of intracellular trafficking of proteins.
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PMID:Novel blockade of cell surface expression of virus glycoproteins by leucinostatin A. 898 41

The participation of nonmuscle myosins in the transport of organelles and vesicular carriers along actin filaments has been documented. In contrast, there is no evidence for the involvement of myosins in the production of vesicles involved in membrane traffic. Here we show that the putative TGN coat protein p200 (Narula, N., I. McMorrow, G. Plopper, J. Doherty, K.S. Matlin, B. Burke, and J.L. Stow. 1992. J. Cell Biol. 114: 1113-1124) is myosin II. The recruitment of myosin II to Golgi membranes is dependent on actin and is regulated by G proteins. Using an assay that studies the release of transport vesicles from the TGN in vitro, we provide functional evidence that p200/myosin is involved in the assembly of basolateral transport vesicles carrying vesicular stomatitis virus G protein (VSVG) from the TGN of polarized MDCK cells. The 50% reduced efficiency in VSVG vesicle release from the TGN in vitro after depletion of p200/myosin II could be reestablished to control levels by the addition of purified nonmuscle myosin II. Several inhibitors of the actin-stimulated ATPase activity of myosin specifically inhibited the release of VSVG-containing vesicles from the TGN.
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PMID:Myosin II is involved in the production of constitutive transport vesicles from the TGN. 923 72


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