201
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Saborío JL, Díaz-Barriga F, Durán G, Tsutsumi V, Palmer E. Purification and characterization of GP-55, a protein associated with actin-based cytoplasmic gels derived from brain tissue. J Biol Chem 1985. [DOI: 10.1016/s0021-9258(17)39518-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022] Open
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202
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Wagner DD, Mayadas T, Urban-Pickering M, Lewis BH, Marder VJ. Inhibition of disulfide bonding of von Willebrand protein by monensin results in small, functionally defective multimers. J Cell Biol 1985; 101:112-20. [PMID: 3924917 PMCID: PMC2113641 DOI: 10.1083/jcb.101.1.112] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
The biosynthesis of von Willebrand protein by human endothelial cells was impaired by the presence of the carboxylic ionophore monensin. Several processing steps that have been localized to the Golgi apparatus were affected in a dose-dependent manner, including carbohydrate processing, dimer multimerization, and precursor cleavage. Since multimerization was more susceptible to the ionophore than was precursor cleavage, it appears that these processing steps are separate events. As expected, dimer formation, which occurs in the rough endoplasmic reticulum, was unaffected by monensin. Thus, at high concentrations of monensin, only dimer molecules were produced and secreted. The observed inhibition of multimer formation and precursor cleavage were not likely the result of incomplete carbohydrate processing, since inhibition of complex carbohydrate formation by swainsonine did not interfere with the other processing steps. Monensin also affected the capacity of endothelial cells to store von Willebrand protein, as the ratio of secreted to cell-associated protein increased dramatically in the presence of monensin, and the processed forms could not be found in the treated cells. The low molecular weight multimers produced in the presence of monensin did not incorporate in the endothelial cells' extracellular matrix nor did they bind to the matrix of human foreskin fibroblasts. In summary, the presence of monensin in human endothelial cell culture produced experimental conditions that mimic Type IIA von Willebrand disease, in that the cells synthesized and secreted only low molecular weight von Willebrand protein multimers, which were functionally defective.
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203
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Cheng B, Horst IA, Kowal J. The Golgi apparatus and adrenal function: the effects of monensin on adrenocorticotropic hormone-stimulated steroidogenesis. Arch Biochem Biophys 1985; 239:508-16. [PMID: 2988453 DOI: 10.1016/0003-9861(85)90719-2] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
It has previously been shown that the steroidogenic action of adrenocorticotropic hormone (ACTH) is accompanied by characteristic alterations in cell ultrastructure. These include hypertrophy of the Golgi complex associated with increased vesicle formation and striking elevations of acid phosphatase activity in the Golgi complex and lysosomes. To investigate a possible relationship of these phenomena to steroidogenic function in monolayer cultures of murine adrenal tumor cells, monensin, a carboxylic ionophore which disrupts the ordered structure and transport function of the Golgi complex, was used. Monensin, at a concentration of 1.2 microM, causes massive vacuolization and hypertrophy of the Golgi complex. No effect on mitochondrial structure was seen. Monensin, 0.6-1.2 microM, inhibits both ACTH-stimulated and basal steroidogenesis by approximately 50% in incubations of 4 h or less. Dibutyryl-cAMP-stimulated steroidogenesis was inhibited to a similar degree. Incubations were carried out in serum-free media to eliminate possible effects due to exogenous cholesterol transport into the cell. There were no direct inhibitory effects of monensin on cholesterol side-chain cleavage (SCC) activity in isolated mitochondria. In contrast, mitochondria isolated from cells previously treated with monensin had a reduced capacity for this activity. These experiments suggest that monensin inhibits transport of cholesterol from the Golgi complex to the mitochondrial site of steroidogenesis action or interferes with the transport of key mitochondrial proteins synthesized on cytoplasmic ribosomes.
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204
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Stevens RL, Parsons WG, Austen KF, Hein A, Caulfield JP. Novel inhibition of proteoglycan synthesis and exocytosis by diethylcarbamazine in the Swarm rat chondrocyte. J Biol Chem 1985. [DOI: 10.1016/s0021-9258(18)89089-5] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
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205
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Namazue J, Campo-Vera H, Kitamura K, Okuno T, Yamanishi K. Processing of virus-specific glycoproteins of varicella zoster virus. Virology 1985; 143:252-9. [PMID: 2998004 PMCID: PMC7130879 DOI: 10.1016/0042-6822(85)90112-6] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Monoclonal antibodies to varicella zoster virus (VZV) glycoproteins were used to study the processing of three glycoproteins with molecular weights of 83K-94K (gp 2), 64K (gp 3), and 55K (gp 5). Immunoprecipitation experiments performed with VZV-infected cells, pulse labeled with [3H]glucosamine in the presence of tunicamycin, suggest that O-linked oligosaccharide is present on the glycoprotein of gp 2. Use of the enzyme endo-beta-N-acetylglucosaminidase H revealed that the fully processed form of gp 3 had high-mannose type and that of gp 5 had only complex type of N-linked oligosaccharides. Experiments with monensin suggest that the precursor form (116K) of gp 3 is cleaved during the processing from Golgi apparatus to cell surface membrane. The extension of O-linked oligosaccharide chain and the complex type of N-linked oligosaccharide chains also occurs during this processing.
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206
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Effects of monensin on the synthesis, transport, and intracellular degradation of proteoglycans in rat ovarian granulosa cells in culture. J Biol Chem 1985. [DOI: 10.1016/s0021-9258(18)89043-3] [Citation(s) in RCA: 54] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
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207
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Sulfation and constitutive secretion of dopamine beta-hydroxylase from rat pheochromocytoma (PC12) cells. J Biol Chem 1985. [DOI: 10.1016/s0021-9258(18)89280-8] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
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208
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Vannier C, Amri EZ, Etienne J, Négrel R, Ailhaud G. Maturation and secretion of lipoprotein lipase in cultured adipose cells. I. Intracellular activation of the enzyme. J Biol Chem 1985. [DOI: 10.1016/s0021-9258(18)89282-1] [Citation(s) in RCA: 59] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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209
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Buckley K, Kelly RB. Identification of a transmembrane glycoprotein specific for secretory vesicles of neural and endocrine cells. J Biophys Biochem Cytol 1985; 100:1284-94. [PMID: 2579958 PMCID: PMC2113776 DOI: 10.1083/jcb.100.4.1284] [Citation(s) in RCA: 588] [Impact Index Per Article: 15.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Several types of cells store proteins in secretory vesicles from which they are released by an appropriate stimulus. It might be expected that the secretory vesicles in different cell types use similar molecular machinery. Here we describe a transmembrane glycoprotein (Mr approximately 100,000) that is present in secretory vesicles in all neurons and endocrine cells studied, in species from elasmobranch fish to mammals, and in neural and endocrine cell lines. It was detected by cross-reactivity with monoclonal antibodies raised to highly purified cholinergic synaptic vesicles from the electric organ of fish. By immunoprecipitation of intact synaptic vesicles and electron microscopic immunoperoxidase labeling, we have shown that the antigenic determinant is on the cytoplasmic face of the synaptic vesicles. However, the electrophoretic mobility of the antigen synthesized in the presence of tunicamycin is reduced to Mr approximately 62,000, which suggests that the antigen is glycosylated and must therefore span the vesicle membrane.
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210
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Klenk HD, Garten W, Rott R. Inhibition of proteolytic cleavage of the hemagglutinin of influenza virus by the calcium-specific ionophore A23187. EMBO J 1985. [PMID: 6441705 PMCID: PMC557788 DOI: 10.1002/j.1460-2075.1984.tb02231.x] [Citation(s) in RCA: 34] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
At calcium-specific ionophore A23187 concentrations of approximately 0.25 microM [which still allow assembly and release of fowl plague virus (FPV) particles] post-translational proteolytic cleavage of the viral hemagglutinin precursor HA into the fragments HA1 and HA2 is inhibited. The resulting virus particles with uncleaved hemagglutinin, that cannot be obtained under normal conditions, provide a suitable substrate for in vitro assays of the protease sensitivity of the FPV hemagglutinin. Proteolytic activation is accomplished with trypsin. Treatment with cathepsin B at low pH yields aberrant cleavage products suggesting that the cellular cleavage enzyme is not of lysosomal origin. A protease that cleaves the FPV hemagglutinin in the correct place can be detected in lysates of MDBK cells. This enzyme is calcium dependent and has a neutral pH optimum.
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211
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Snider MD, Rogers OC. Intracellular movement of cell surface receptors after endocytosis: resialylation of asialo-transferrin receptor in human erythroleukemia cells. J Cell Biol 1985; 100:826-34. [PMID: 2982885 PMCID: PMC2113516 DOI: 10.1083/jcb.100.3.826] [Citation(s) in RCA: 197] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
The intracellular movement of cell surface transferrin receptor (TfR) after internalization was studied in K562 cultured human erythroleukemia cells. The sialic acid residues of the TfR glycoprotein were used to monitor transport to the Golgi complex, the site of sialyltransferases. Surface-labeled cells were treated with neuraminidase, and readdition of sialic acid residues, monitored by isoelectric focusing of immunoprecipitated TfR, was used to assess the movement of receptor to sialyltransferase-containing compartments. Asialo-TfR was resialylated by the cells with a half-time of 2-3 h. Resialylation occurred in an intracellular organelle, since it was inhibited by treatments that allow internalization of surface components but block transfer out of the endosomal compartment. Moreover, roughly half of the resialylated molecules were cleaved when cells were retreated with neuraminidase after culturing, indicating that this fraction of the molecules had returned to the cell surface. These results suggest that TfR is transported from the cell surface to the Golgi complex, the intracellular site of sialyltransferases, and then returns to the cell surface. This pathway, which has not been previously described for a cell surface receptor, may be different from the route followed by TfR in iron uptake, since reported rates of transferrin uptake and release are significantly more rapid than the resialylation of asialo-TfR.
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212
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Burditt LJ, Ratcliffe A, Fryer PR, Hardingham TE. The intracellular localisation of proteoglycans and their accumulation in chondrocytes treated with monensin. BIOCHIMICA ET BIOPHYSICA ACTA 1985; 844:247-55. [PMID: 3918582 DOI: 10.1016/0167-4889(85)90097-7] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Pig laryngeal chondrocytes incubated in the presence of monensin showed inhibition of [35S]sulphate incorporation and decreased secretion of proteoglycan into the culture medium, but no large decrease in protein synthesis. This lead to the intracellular accumulation of proteoglycan protein core, which was detected in immunoprecipitates of cell extracts. Using the same antiserum protein core was localised by electron microscopy with protein A-coated gold. In control chondrocytes, it was detected only in elements of the Golgi and in secretory vesicles, but following monensin treatment labelling was more intense in the Golgi and extended into the distended cisternae of the rough endoplasmic reticulum. The results suggest that monensin blocks proteoglycan protein core translocation between different elements of the Golgi and that this occurs prior to the major site of chondroitin sulphate synthesis on proteoglycan.
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213
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Anderson J, Byrne JA, Schreiber R, Patterson S, Oldstone MB. Biology of cloned cytotoxic T lymphocytes specific for lymphocytic choriomeningitis virus: clearance of virus and in vitro properties. J Virol 1985; 53:552-60. [PMID: 3918175 PMCID: PMC254670 DOI: 10.1128/jvi.53.2.552-560.1985] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
We have generated lymphocytic choriomeningitis virus-specific, H-2-restricted cytotoxic thymus-derived lymphocyte (CTL) clones. By using these reagents in several in vitro assays with infected target cells, we show that CTLs by themselves prevent the release of infectious virus into culture fluids and significantly lower the titers of infectious virus previously produced. This ability of cloned CTLs is not influenced by monensin. However, monensin does abrogate the ability of CTLs from spleens of mice primed 6 to 8 days previously with virus to kill virus-infected syngeneic targets. When tested for the participation of lymphokines in this system, the CTLs proliferate when reacted with syngeneic lymphocytic choriomeningitis virus-infected macrophages but fail to make interleukin-2. These CTLs make gamma interferon when reacted with syngeneic virus-infected targets. However, the production of interferon does not directly correlate with CTL-mediated killing. The number of H-2K and D molecules expressed on the target cell surface is not altered during the course of lymphocytic choriomeningitis virus infection. Electron microscopy shows finger-like projections of the CTL clone thrust into the infected cell and lesions bearing an internal diameter of approximately 15 nm in those membranes, illustrating the lytic process.
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214
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Abstract
Polylysine promoted extensive membrane mixing of liposomes only if the buffer pH was below the pKa of the lysyl residues. This observation suggested that fusion could be regulated in a physiological pH range if the homopolymer of L-histidine was substituted as fusogen. Microgram quantities of polyhistidine were added to liposomes composed of soybean phospholipids, or to defined phospholipid-cholesterol mixtures which simulate the lipid composition of plasma membranes. A quantitative resonance energy transfer assay determined the extent of lipid phase mixing related to fusion. No fusion was detected at pH 7.4, but when the pH was lowered to 6.5 or below, fusion was rapid and substantial. The extent of membrane mixing increased with progressive acidification of the vesicle-fusogen suspension. The charge density of each polyhistidine molecule, not the total cationic charge per vesicle, influenced the extent of fusion. The kinetics of the fusion reaction were rapid, as membrane mixing was completed within 1 min. If the vesicle suspension was acidified before fusogen addition, the rate of membrane mixing slowed 4-fold. This, as well as a slight increase in light scattering noted whenever polyhistidine was added at pH 7.4, suggests an enhancement of fusion kinetics by preaggregation of vesicles at neutral pH. The lipid composition, regulation of membrane mixing by pH in a physiological range, and rapid kinetics suggest that this model of liposome fusion may be pertinent to understanding some biological fusion events.
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215
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Exit of nonglycosylated secretory proteins from the rough endoplasmic reticulum is asynchronous in the exocrine pancreas. J Biol Chem 1985. [DOI: 10.1016/s0021-9258(20)71188-9] [Citation(s) in RCA: 52] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
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216
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Abstract
Altogether 30 different sugar analogues have been tested in a cell free system from rat liver or, in part, in freshly prepared hepatocytes. It is our aim to find suitable compounds which are able either to interfere with the metabolization of L-fucose, galactose and N-acetylmannosamine or, alternatively, to block the attachment of these sugars to the nascent oligosaccharide chain. 1-Methylfucoside inhibits the fucokinase by a competitive mode (Ki = 1.1 mmol/l). Both the fucokinase and fucose-1-phosphate pyrophosphorylase activity are impaired by Clobenoside, a chloro-containing glucofuranoside (Ki values between 5 to 10 mmol/l). In hepatocytes this inhibition leads to a drastic reduction of fucoprotein biosynthesis and secretion. 1-Methylenegalactose proved to be a promising competitive inhibitor of the galactokinase (Ki = 4.1 mmol/l), while the efficacy of 2-deoxy-2-fluoro-galactose and 6-deoxy-6-fluoro-galactose is less pronounced. Part of these sugar analogues could become a suitable tool in order to elucidate the biological significance of terminal and subterminal sugars.
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217
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Welsh AO, Enders AC. Light and electron microscopic examination of the mature decidual cells of the rat with emphasis on the antimesometrial decidua and its degeneration. THE AMERICAN JOURNAL OF ANATOMY 1985; 172:1-29. [PMID: 3969928 DOI: 10.1002/aja.1001720102] [Citation(s) in RCA: 109] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Rat gestation sites were obtained on days 10 through 16 of normal pregnancy. Light and electron microscopic examination of day-10 sites revealed a consistent complex pattern of stromal cell morphologies. Six distinct regions were identified: an antimesometrial region of epithelioid decidual cells that form the gestation chamber containing the embryo and extraembryonic membranes; an abembryonic antimesometrial decidual region, the decidual crypt, where the cells are separated by large extracellular spaces; a mesometrial region with granule-containing cells and mesometrial decidual cells; a region of spiny cells that are lateral to the antimesometrial decidual cells and continuous with the mesometrial decidual cells; and a region of undifferentiated stromal cells adjacent to the myometrium. Between days 12 and 16, the antimesometrial decidua becomes thinner and is eventually sloughed into the newly formed uterine lumen. The role of the antimesometrial decidual cells is discussed with reference to trophoblast invasiveness, protein synthesis, and especially remodeling of the gestation chamber. Differences between decidua and deciduoma are considered.
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218
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Heumann R, Korsching S, Scott J, Thoenen H. Relationship between levels of nerve growth factor (NGF) and its messenger RNA in sympathetic ganglia and peripheral target tissues. EMBO J 1984; 3:3183-9. [PMID: 6549295 PMCID: PMC557836 DOI: 10.1002/j.1460-2075.1984.tb02277.x] [Citation(s) in RCA: 291] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
We have developed a sensitive assay for the quantification of nerve growth factor mRNA (mRNANGF) in various tissues of the mouse using in vitro transcribed RNANGF. Probes of both polarities were used to determine the specificity of the hybridization signals obtained. Comparison of NGF levels with its mRNA revealed that both were correlated with the density of sympathetic innervation. Thus, vas deferens contained high levels of both NGF and mRNANGF, whereas skeletal muscle levels were barely detectable, indicating that in peripheral tissues NGF levels are primarily regulated by the quantity of mRNANGF and not by the rate of processing of NGF precursor to NGF. However, although superior cervical ganglia contained the highest levels of NGF, its mRNA was barely detectable. Thus, the high levels of NGF in sympathetic ganglia result from retrograde axonal transport rather than local synthesis. The quantity of NGF found in the submandibular glands of female animals was three orders of magnitude higher than expected from their mRNA levels. This observation is discussed in the context of the difference between the mechanism of storage and exocytosis of exocrine glands versus the constitutive release from other tissues.
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219
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Vladutiu GD. Immunocytochemical localization of beta-hexosaminidase and electron-microscopic characterization of human fibroblasts following treatment with monensin and nigericin. Biosci Rep 1984; 4:1079-88. [PMID: 6241482 DOI: 10.1007/bf01116702] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Immunocytochemical localization of beta-hexosaminidase in cultured human skin fibroblasts was performed in the presence or absence of the Na+/K+ ionophores monensin and nigericin. In the presence of monensin, beta-hexosaminidase accumulated in the periphery of swollen vesicles in the paranuclear region of fibroblasts from normal individuals and from patients with mucolipidosis II. Nigericin-treated cells had more extensive vacuolization of the cytoplasm and the localization of the enzyme was more diffuse within these vacuoles. Morphological studies at the ultrastructral level indicated that a perturbation of the Golgi region occurred during ionophore treatment. These findings suggest that beta-hexosaminidase in ionophore-treated fibroblasts is trapped in a time- and dose-dependent manner in the paranuclear region presumed to be the swollen cisternae of the Golgi region, or adjacent vesicles derived from the Golgi region. Furthermore, fibroblasts are more sensitive to perturbation by nigericin than by monensin at similar concentrations and exposure times. These data support biochemical findings that the two ionophores differentially inhibit the transport of lysosomal enzymes in the Golgi region.
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220
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Wagner DD, Marder VJ. Biosynthesis of von Willebrand protein by human endothelial cells: processing steps and their intracellular localization. J Cell Biol 1984; 99:2123-30. [PMID: 6334089 PMCID: PMC2113568 DOI: 10.1083/jcb.99.6.2123] [Citation(s) in RCA: 237] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Biosynthesis of von Willebrand protein by human umbilical vein endothelial cells involved distinct processing steps marked by the presence of several intermediate molecular species. Examination of endoglycosidase H sensitivity of these intracellular intermediates indicated that the processing steps occurred in at least two separate cellular compartments. In the pre-Golgi apparatus (most probably the endoplasmic reticulum), the high mannose carbohydrates were added onto the precursor monomer chains and the 260,000-mol-wt monomers dimerized by interchain disulfide bond formation. The other processing steps have been localized to the Golgi apparatus and later compartments (e.g., Weibel-Palade bodies). High mannose carbohydrate was converted to the complex type, leading to the appearance of a larger precursor subunit of 275,000 mol wt. The 275,000-mol-wt species was not formed if carbohydrate processing was inhibited by the ionophore monensin. From the large pool of dimers of precursor subunits, the high molecular weight multimers were built. These dimer molecules appeared to have free sulfhydryls which might have been involved in the interdimer disulfide bond formation. Simultaneously with multimerization, the precursor subunits were cleaved to the 220,000-mol-wt form. The cleavage of the pro-sequence was not likely to be an absolute requirement for von Willebrand protein multimerization or secretion, as the 275,000-mol-wt precursor subunit was present in secreted high molecular weight multimers of the protein.
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221
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Flickinger CJ, Wilson KM, Gray HD. The secretory pathway in the mouse epididymis as shown by electron microscope radioautography of principal cells exposed to monensin. Anat Rec (Hoboken) 1984; 210:435-48. [PMID: 6524687 DOI: 10.1002/ar.1092100304] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
The secretory pathway in principal cells of the mouse epididymis was studied using in vitro labeling and electron microscope radioautography of tissue exposed to the ionophore monensin. After a 5-minute pulse of 3H-leucine, control samples of caput epididymidis were incubated in a modified Krebs-Ringer solution (MKRH medium), while experimental specimens were placed in the same medium, to which 1 microM monensin had been added. At intervals between 5 minutes and 4 hours, samples were fixed and prepared for electron microscope radioautography. Analysis of control specimens revealed heaviest labeling of the rough and the sparsely granulated endoplasmic reticulum early in the experiment followed by a fall in radioactivity, maximal labeling of the Golgi apparatus at 30 minutes, and a pronounced rise in the percentage of grains associated with the apical cell surface and the epididymal lumen beginning 1 hour after administration of precursor. In monensin-treated epididymides, radioactive material accumulated in the Golgi region while the normal increase in labeling of the apical surface and the lumen was completely inhibited for at least 2 hours. The percentage of grains attributed to coated vesicles was also reduced in samples exposed to monensin. In contrast, labeling patterns of the abundant, sparsely granulated, endoplasmic reticulum and the rough endoplasmic reticulum were very similar in monensin-treated and control specimens. The concomitant alterations in labeling of the Golgi apparatus and the lumen demonstrate that the Golgi apparatus participates in intracellular transport of secretory proteins in epididymal principal cells, and is not bypassed as previously suggested. The percentage of grains associated with the sparsely granulated endoplasmic reticulum suggests that much of the synthesis of secretory protein in the principal cells occurs in this organelle, and the lack of alteration of its labeling in the presence of a monensin-induced block at the level of the Golgi apparatus indicates that the sparsely granulated endoplasmic reticulum lies before the Golgi apparatus in the secretory pathway. It is speculated that vesicles play a role in transport of secretory protein from the Golgi apparatus to the lumen.
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222
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Orci L, Halban P, Amherdt M, Ravazzola M, Vassalli JD, Perrelet A. A clathrin-coated, Golgi-related compartment of the insulin secreting cell accumulates proinsulin in the presence of monensin. Cell 1984; 39:39-47. [PMID: 6386182 DOI: 10.1016/0092-8674(84)90189-2] [Citation(s) in RCA: 123] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
When the intracellular transit of 3H-labeled (pro)-insulin polypeptides is perturbed by monensin in the pancreatic B-cell, proinsulin conversion is impaired and the radioactive peptides accumulate in a clathrin-coated membrane compartment related to the Golgi apparatus. Clathrin was demonstrated by immunocytochemistry using the postembedding protein A-gold technique. The coated compartment, which is dilated by monensin, comprises Golgi cisternae with condensing secretory material and newly formed secretory granules; under monensin block, the noncoated (storage) secretory granules do not become significantly labeled. These data suggest that an unperturbed passage through a Golgi-related, clathrin-coated membrane compartment which subsequently matures into noncoated secretory granules is needed for the normal processing of (pro)insulin polypeptides.
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223
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Effect of tunicamycin and monensin on secretion of thyroxine-binding globulin by cultured human hepatoma (Hep G2) cells. J Biol Chem 1984. [DOI: 10.1016/s0021-9258(18)90737-4] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
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224
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Gold G, Grodsky GM. Kinetic aspects of compartmental storage and secretion of insulin and zinc. EXPERIENTIA 1984; 40:1105-14. [PMID: 6092127 DOI: 10.1007/bf01971458] [Citation(s) in RCA: 49] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
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225
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Melin B, Keller G, Glass C, Weinstein DB, Steinberg D. Lipoprotein synthesis and secretion by cultured rat hepatocytes. Parallel inhibition of secretion of VLDL, HDL and albumin by monensin. BIOCHIMICA ET BIOPHYSICA ACTA 1984; 795:574-88. [PMID: 6477962 DOI: 10.1016/0005-2760(84)90188-7] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
The biosynthesis and secretion of very-low-density lipoproteins (VLDL) and high-density lipoproteins (HDL) by cultured normal rat hepatocytes was investigated with particular emphasis on its modification by monensin. This acidic ionophore coordinately inhibited the rates of secretion of the several VLDL apolipoproteins and the VLDL lipids, suggesting an effect late in the process of biosynthesis and secretion, probably at the stage of exiting from the Golgi apparatus. The secretion of immunoreactive albumin into the medium was comparably inhibited, implying that the pathway and mechanisms involved in albumin secretion may be closely similar to those for VLDL synthesis and secretion. Secretion of phospholipids and of apolipoproteins E and A-I in the HDL fraction increased progressively with time over 18 h in control incubations but was strongly inhibited by monensin. During extended incubation with monensin at high concentrations (10 microM), there was a net release to the medium of a number of hepatocyte proteins, including some that comigrated with apolipoprotein A-I and apolipoprotein C, making it appear that monensin increased the secretion of these apolipoproteins. However, using labeled amino acids, it was shown by autoradiography and by immunoprecipitation that secretion of newly-synthesized, radioactive apolipoprotein A-I and apolipoprotein C was actually inhibited by monensin. These results are compatible with the conclusion that HDL synthesis and secretion may occur by mechanisms closely related to those for synthesis and secretion of albumin and VLDL.
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226
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Abstract
Desensitization of beta-receptor-linked adenylate cyclase occurs after prolonged occupancy of the beta-receptors by their agonists. We have followed the development and recovery from "down"-regulation of beta-receptors in enzymatically dissociated cardiac myocytes by using the hydrophilic antagonist [3H]-CGP-12177 to identify surface-bound beta-receptors. After in vitro incubation with (-)-isoproterenol, almost 50% of the beta-receptors are lost within 10 minutes. Isoproterenol-mediated cyclic adenosine monophosphate accumulation by isolated myocytes was also decreased after a 15-minute preincubation with isoproterenol. "Lost" beta-receptors can, however, be recovered when isoproterenol-pretreated, washed cardiac myocytes are incubated at 37 degrees C, 85 +/- 7% of the lost beta-receptors have returned to the cell surface after 20 minutes of incubation. The requirements for such recycling were investigated. Receptor recovery does not depend on de novo protein synthesis, since it is unaffected by prior exposure to cycloheximide. It is, however, dependent on cellular energy, because it is prevented by adenosine triphosphate depletion and involves a lysosomal step since it is inhibited by the lysomotropic agent, chloroquine. In addition, the Golgi apparatus and the microtubules are involved in the beta-receptor recycling to the cell surface, as evidenced by the inhibitory effects of monensin and colchicine, respectively. The mechanism of isoproterenol-induced down-regulation of cardiac beta-receptors involves a rapid, reversible cycling to and from the cytosol and the cell membrane. This intracellular receptor traffic is energy dependent, requires several structures, including lysosomes and microtubules, and may be modified by pathological processes involving the heart.
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227
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Sai S, Tanzer ML. Reversibility of monensin inhibition of oligosaccharide processing of human fibronectin. Exp Cell Res 1984; 154:402-11. [PMID: 6479236 DOI: 10.1016/0014-4827(84)90164-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Monensin impairs oligosaccharide processing in fibronectin primarily by inhibiting the conversion of oligosaccharides from the high mannose type to the complex type. The separate effects of monensin and cations on alpha-mannosidase activity in fibroblasts were examined using an in vitro assay system. The results indicated that monensin did not directly inhibit alpha-mannosidase activity in vitro, although prior treatment of fibroblasts with monensin caused an irreversible suppression of enzyme activity. The reversibility of monensin action on oligosaccharide processing was also examined. Analyses using concanavalin A (ConA) Sepharose affinity chromatography showed that the inhibitory action of monensin on oligosaccharide processing was biologically reversible. A progressive return to complex type oligosaccharides began about 11 h after the removal of the monensin. These composite results indicate that the reversibility of monensin action on oligosaccharide processing in fibronectin may be attributed to the restoration of enzyme activity, although the mechanism by which restoration occurs remains to be deciphered.
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228
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Bumol TF, Walker LE, Reisfeld RA. Biosynthetic studies of proteoglycans in human melanoma cells with a monoclonal antibody to a core glycoprotein of chondroitin sulfate proteoglycans. J Biol Chem 1984. [DOI: 10.1016/s0021-9258(18)90807-0] [Citation(s) in RCA: 72] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
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229
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Misumi Y, Takami N, Ikehara Y. Biosynthesis and processing of pro-C3, a precursor of the third component of complement in rat hepatocytes: effect of secretion-blocking agents. FEBS Lett 1984; 175:63-7. [PMID: 6479339 DOI: 10.1016/0014-5793(84)80570-0] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Biosynthesis and intracellular processing of the third component (C3) of complement were studied in cultured rat hepatocytes. In the control cells, the complement C3 was synthesized as a pro-form, a single polypeptide chain comprising both the alpha- and beta-subunits. Although the cleavage of the pro-form into the subunits was not clearly demonstrable within the cells during pulse-chase periods, all the secreted C3 was the mature processed form. The cells were treated with secretion-blocking agents with different modes of action, colchicine and monensin. Colchicine caused an accumulation of the processed C3 within the cells, whereas monensin blocked the secretion without a significant accumulation of the processed form. The results indicate that the conversion of the C3 pro-form into the subunits takes place in the secretory vesicles just before the secretion.
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230
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Brooks DE. Protein secretion by the rat epididymis can be selectively modified in vitro by local anesthetics, glucose deprivation, dinitrophenol, ouabain, and ionophores. JOURNAL OF ANDROLOGY 1984; 5:351-60. [PMID: 6438036 DOI: 10.1002/j.1939-4640.1984.tb00801.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Protein secretion by the caput epididymidis has been examined in vitro using radioactive methionine as a precursor for protein synthesis. Newly synthesized and secreted proteins were separated by gel electrophoresis and visualized by fluorography. Local anesthetics such as procaine had the ability to reduce the secretion of some, but not all, proteins. Selective inhibition of secretion of the same proteins occurred when either dihydrocytochalasin B, monensin, ouabain, or dinitrophenol was added to the medium, or when the concentration of glucose was reduced below 1 mM. Calcium ionophore also selectively modified protein secretion, but the proteins affected were different from those influenced by local anesthetics. Other agents tested (eg, adrenergic and cholinergic agonists and antagonists, sodium pentobarbitone, antipsychotic drugs, cyclic AMP, colchicine) did not selectively modify protein secretion, even though overall protein synthesis and secretion was reduced in some instances. Procaine and dihydrocytochalasin B also reduced glucose utilization by epididymal tissue and it is suggested that these agents may reduce protein secretion by limiting the supply of energy for the exocytotic process. This conclusion is supported by the fact that dinitrophenol, an uncoupler of oxidative phosphorylation, caused a similar alteration in protein secretion. The possibility that a restricted energy supply modifies protein secretion primarily by creating a disturbed intracellular Na/K balance is suggested by the observation that the monovalent ionophore, monensin, and the Na/K ATPase inhibitor, ouabain, were both able to duplicate the effects of the local anesthetics.
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231
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van Kampen GP, van Steenbergen TJ, Schipper CA, de Graaff J, Veldhuijzen JP. Proteoglycan production by chick embryonic chondrocytes is inhibited by culture filtrate of Bacteroides gingivalis. J Periodontal Res 1984; 19:483-8. [PMID: 6238146 DOI: 10.1111/j.1600-0765.1984.tb01303.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
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232
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Pizzey J, Witkowski J, Jones G. Monensin-induced inhibition of cell spreading in normal and dystrophic human fibroblasts. Proc Natl Acad Sci U S A 1984; 81:4960-4. [PMID: 6589639 PMCID: PMC391612 DOI: 10.1073/pnas.81.15.4960] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
Cultured skin fibroblasts from normal individuals and from patients with Duchenne muscular dystrophy spread equally rapidly when seeded on a glass substratum. Exposure to the ionophore monensin substantially suppresses normal and dystrophic fibroblast spreading in serum-free media for up to at least 100 min. Preincubation of normal fibroblasts with monensin causes a further reduction in cell spreading. Dystrophic fibroblasts fail to spread as well as normal cells after monensin preincubation. Such findings indicate that there is a delay in the secretion of functional adhesive surface proteins in monensin-preincubated normal fibroblasts and that this lag period is significantly longer in dystrophic fibroblasts. These data are consistent with findings of altered adhesive and secretory properties of fibroblasts from patients with Duchenne muscular dystrophy.
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233
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Abstract
Monensin and colchicine have been used in a variety of systems to disrupt functioning of the Golgi apparatus and transport of Golgi-derived vesicles to the plasma membrane. In this study the effects of monensin and colchicine on the synthesis of cerebroside and sulfatide and their appearance in myelin were examined to determine whether these myelin components are processed through the Golgi apparatus. Brain slices from rats 17 days old were incubated with [3H]galactose and [35S]-sulfate to label cerebroside and sulfatide. Myelin was isolated on sucrose density gradients. Fractions highly enriched in cerebroside and sulfatide were prepared from homogenates and myelin fractions by lipid extraction, alkaline methanolysis, and in some cases TLC. Monensin at 0.1 microM had no significant effect on synthesis of these galactolipids as measured by incorporation of [3H]-galactose into cerebroside or [35S]sulfate into sulfatide in homogenates. However, appearance of [35S]sulfatide in the myelin fraction was reduced to 49% of control, while appearance of [3H]cerebroside was not significantly reduced. Colchicine from 1 mM to 0.1 microM had effects similar to monensin, that is, appearance of [35S]sulfatide in myelin was depressed, but again [3H]cerebroside was not affected. Incorporation of [35S]sulfate into sulfatide in homogenate was 93% of control, while appearance of [35S]sulfatide in the myelin fraction was depressed to 58% of control. The inhibition of appearance of sulfatide in myelin by colchicine and monensin is consistent with the view that sulfation of cerebroside occurs in the Golgi and that sulfatide is transported via Golgi-derived vesicles to the forming myelin membrane.(ABSTRACT TRUNCATED AT 250 WORDS)
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Wileman T, Boshans RL, Schlesinger P, Stahl P. Monensin inhibits recycling of macrophage mannose-glycoprotein receptors and ligand delivery to lysosomes. Biochem J 1984; 220:665-75. [PMID: 6087792 PMCID: PMC1153682 DOI: 10.1042/bj2200665] [Citation(s) in RCA: 130] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Binding studies with cells that had been permeabilized with saponin indicate that alveolar macrophages have an intracellular pool of mannose-specific binding sites which is about 4-fold greater than the cell surface pool. Monensin, a carboxylic ionophore which mediates proton movement across membranes, has no effect on binding of ligand to macrophages but blocks receptor-mediated uptake of 125I-labelled beta-glucuronidase. Inhibition of uptake was concentration- and time-dependent. Internalization of receptor-bound ligand, after warming to 37 degrees C, was unaffected by monensin. Moreover, internalization of ligand in the presence of monensin resulted in an intracellular accumulation of receptor-ligand complexes. The monensin effect was not dependent on the presence of ligand, since incubation of macrophages with monensin at 37 degrees C without ligand resulted in a substantial decrease in cell-surface binding activity. However, total binding activity, measured in the presence of saponin, was much less affected by monensin treatment. Removal of monensin followed by a brief incubation at pH 6.0 and 37 degrees C, restored both cell-surface binding and uptake activity. Fractionation experiments indicate that ligands enter a low-density (endosomal) fraction within the first few minutes of uptake, and within 20 min transfer to the lysosomal fraction has occurred. Monensin blocks the transfer from endosomal to lysosomal fraction. Lysosomal pH, as measured by the fluorescein-dextran method, was increased by monensin in the same concentration range that blocked ligand uptake. The results indicate that monensin blockade of receptor-mediated endocytosis of mannose-terminated ligands by macrophages is due to entrapment of receptor-ligand complexes and probably receptors in the pre-lysosomal compartment. The inhibition is linked with an increase in the pH of acid intracellular vesicles.
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236
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Geetha-Habib M, Campbell SC, Schwartz NB. Subcellular localization of the synthesis and glycosylation of chondroitin sulfate proteoglycan core protein. J Biol Chem 1984. [DOI: 10.1016/s0021-9258(17)39872-1] [Citation(s) in RCA: 49] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
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237
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Smith ZD, D'Eugenio-Gumkowski F, Yanagisawa K, Jamieson JD. Endogenous and monoclonal antibodies to the rat pancreatic acinar cell Golgi complex. J Cell Biol 1984; 98:2035-46. [PMID: 6373788 PMCID: PMC2113066 DOI: 10.1083/jcb.98.6.2035] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Normal, unimmunized mouse serum from several strains (BALB/c, C57/b, DBA/2, NZB, SJL, CD/1) contains an endogenous IgG antibody that localizes to the Golgi complex of rat pancreatic acinar cells. Treatment of pancreatic acini with 5 microM monensin resulted in the swelling and vacuolization of the Golgi cisternae, and in a corresponding annular staining by the mouse serum as observed by immunofluorescence, suggesting that the antigen recognized is on the Golgi complex cisternal membrane. The antiserum did not react with pancreatic secretory proteins, and its binding to smooth microsomal membranes was retained following sodium carbonate washing, supporting a Golgi membrane localization. Advantage was taken of the existence of the endogenous murine antibody for the isolation of monoclonal antibodies directed to the Golgi complex of the rat pancreas. Two antibodies, antiGolgi 1 and antiGolgi 2, are described. Both antibodies are IgMs that recognize integral membrane proteins of the trans-Golgi cisternae, with lighter and patchy staining of the pancreatic lumen membrane, as observed both by light and electron microscopy. AntiGolgi 1 recognizes predominately a protein of molecular weight 103,000-108,000, whereas antiGolgi 2 shows a strong reaction to a 180-kd band as well as the 103-108-kd protein.
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238
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Ono M, Yamato H, Ando M, Kuwano M. Chinese hamster ovary cell variants resistant to monensin, an ionophoric antibiotic. I. Isolation and altered endocytosis of ricin. J Cell Physiol 1984; 119:198-203. [PMID: 6715418 DOI: 10.1002/jcp.1041190209] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Chinese hamster ovary (CHO) cell variants resistant to a carboxylic ionophore, monensin, have been isolated. Two monensin-resistant variants (MonR-31 and MonR-32) showed a three- to fourfold higher resistance to monensin than did CHO. These MonR clones also showed fourfold higher resistance to another carboxylic ionophore, nigericin, and twofold higher resistance to valinomycin. They were also slightly more resistant to other unrelated drugs such as adriamycin, colchicine, bleomycin, and chloroquine, and in particular, they showed about threefold higher resistance to ricin, a toxin of Ricinus communis. MonR clones were found to retain a normal level of [125I]ricin binding, but internalization of [125I]ricin into the MonR clones was one-half or less than with CHO. Present data suggest that drug-resistant clones selected in culture may provide a way to isolate cells with altered response to various bioactive molecules.
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239
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Mitsui T, Christeller JT, Hara-Nishimura I, Akazawa T. Possible roles of calcium and calmodulin in the biosynthesis and secretion of alpha-amylase in rice seed scutellar epithelium. PLANT PHYSIOLOGY 1984; 75:21-5. [PMID: 16663573 PMCID: PMC1066827 DOI: 10.1104/pp.75.1.21] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
The scutellar epithelial cells of rice (Oryza sativa L. cv Kimmazé) seeds actively secrete alpha-amylase in an early stage of germination. Employing an in vivo system of freshly dissected scutellar tissues, effect of Ca(2+) on the biosynthesis and the secretion of alpha-amylase have been studied. The maximum biosynthetic rate was saturated at about 0.5 mm external Ca(2+) concentrations, whereas the secretion continued to increase to concentrations above 10 mm Ca(2+). In the presence of 1 mm Ca(2+), 0.01 mum A-23187 significantly increased both the biosynthesis and the secretion of alpha-amylase.A cation-specific requirement for Ca(2+) was apparent, since both biosynthesis and extracellular secretion of alpha-amylase were inhibited by 0.1 mm EGTA but were increased above basal rate only with Ca(2+) and Sr(2+); K(+), Mg(2+), and Ba(2+) being ineffective.La(3+) and ruthenium red (selective inhibitors of [Ca(2+) + Mg(2+)]-ATPase) were found to profoundly inhibit the secretion of alpha-amylase. A calmodulin antagonist, W-7, also inhibited the secretion of alpha-amylase at concentrations where the enzyme synthesis was not much affected. Overall data indicate that Ca(2+) movement and secretion of alpha-amylase are tightly linked and it is likely that they are regulated by the cytoplasmic Ca(2+) concentration under possible control by calmodulin.
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Affiliation(s)
- T Mitsui
- Research Institute for Biochemical Regulation, School of Agriculture, Nagoya University, Chikusa, Nagoya 464, Japan
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240
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Burke B, Warren G. Microinjection of mRNA coding for an anti-Golgi antibody inhibits intracellular transport of a viral membrane protein. Cell 1984; 36:847-56. [PMID: 6323023 PMCID: PMC7133283 DOI: 10.1016/0092-8674(84)90034-5] [Citation(s) in RCA: 35] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Messenger RNA was prepared from a hybridoma cell line secreting a monoclonal antibody (53FC3) directed against a luminal epitope of a Golgi membrane protein (Mr = 135 kd) found in rodent cells. When this mRNA was microinjected into the cytoplasm of BHK cells, mouse IgG was seen to accumulate in the Golgi complex after 5-6 hr of incubation. No accumulation was seen in 3T3 cells which lack the epitope recognized by 53FC3. When microinjected BHK cells were infected with vesicular stomatitis virus, surface expression of the viral G protein was considerably reduced when compared with neighboring noninjected cells.
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241
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Goud B, Antoine JC. Emergence of a surface immunoglobulin recycling process during B lymphocyte differentiation. J Biophys Biochem Cytol 1984; 98:1238-46. [PMID: 6609161 PMCID: PMC2113222 DOI: 10.1083/jcb.98.4.1238] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Surface immunoglobulin (Ig)-mediated endocytosis has been investigated in rat B lymphocytes and plasma cells, using horseradish peroxidase (HRP)-labeled sheep anti-rat Ig Fab' fragment of antibody and HRP as monomeric ligands, respectively. Quantitative estimates of HRP activity associated either with plasma membrane or with endomembrane compartments were made in several experimental conditions. Binding of HRP-conjugate on B lymphocytes was followed by its endocytosis in combination with surface Ig, as shown by the progressive disappearance of plasma membrane-associated HRP activity. Between 1 and 6 h at 37 degrees C in presence of conjugate the total amount of cell-associated activity was constant. These results indicate that during this time no reappearance of surface Ig occurred by neosynthesis, by the expression of an intracellular pool or by the recycling in a free form of the previously internalized molecules. On the contrary, at saturating doses, internalization of HRP by anti-HRP plasma cells increased linearly with time at 37 degrees C in presence of antigen, when, during the same time, the plasma membrane HRP-binding capacity remained constant. Cycloheximide did not affect continuous HRP uptake. The existence of a large intracellular pool of receptors has been ruled out by experiments of removal of binding sites with pronase. In addition, monensin caused a progressive decrease in the number of surface receptors on plasma cells but not on B lymphocytes. Our data then indicate that, unlike B lymphocytes, plasma cells were able to recycle their surface Ig.
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242
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Castillo FJ, Penel C, Greppin H. Peroxidase Release Induced by Ozone in Sedum album Leaves: Involvement of Ca. PLANT PHYSIOLOGY 1984; 74:846-51. [PMID: 16663520 PMCID: PMC1066779 DOI: 10.1104/pp.74.4.846] [Citation(s) in RCA: 166] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
The effect of ozone was studied on the peroxidase activity from various compartments of Sedum album leaves (epidermis, intercellular fluid, residual cell material, and total cell material). The greatest increase following a 2-hour ozone exposure (0.4 microliters O(3) per liter) was observed in extracellular peroxidases. Most of the main bands of peroxidase activity separated by isoelectric focusing exhibited an increase upon exposure to ozone. Incubation experiments with isolated peeled or unpeeled leaves showed that leaves from ozone-treated plants release much more peroxidases in the medium than untreated leaves. The withdrawal of Ca(2+) ions reduced the level of extracellular peroxidase activity either in whole plants or in incubation experiments. This reduction and the activation obtained after addition of Ca(2+) resulted from a direct requirement of Ca(2+) by the enzyme and from an effect of Ca(2+) on peroxidase secretion. The ionophore A23187 promoted an increase of extracellular peroxidase activity only in untreated plants. The release of peroxidases by untreated and ozone-treated leaves is considerably lowered by metabolic inhibitors (3-(3,4-dichlorophenyl)-1,1-dimethylurea and sodium azide) and by puromycin.
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Affiliation(s)
- F J Castillo
- Laboratoire de Physiologie Végétale, Université de Genève, 3 Place de l'Université, 1211 Genève 4, Switzerland
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243
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Devault A, Zollinger M, Crine P. Effects of the monovalent ionophore monensin on the intracellular transport and processing of pro-opiomelanocortin in cultured intermediate lobe cells of the rat pituitary. J Biol Chem 1984. [DOI: 10.1016/s0021-9258(17)42968-1] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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244
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Bonser AM, Garcia-Webb P. Acute effects of insulin on surface insulin receptors in isolated hepatocytes. Evidence for a recycling pathway. Biochem Biophys Res Commun 1984; 119:706-12. [PMID: 6370247 DOI: 10.1016/s0006-291x(84)80308-3] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Isolated rat hepatocytes were incubated for 1 h at 37 degrees C with 10 nM insulin. Following washout of insulin, cells were incubated with [125I] monoiodoinsulin at 15 degrees C to assess surface insulin binding. Preincubation with 10 nM insulin did not cause a decrease in insulin binding. Scatchard analysis confirmed that insulin receptor number remained constant. In the presence of 200 microM chloroquine or 25 microM monensin, surface insulin binding after preincubation with 10 nM insulin fell to 81.1 +/- 1.2% or 39.0 +/- 2.7% of control, respectively. It is suggested that the maintenance of insulin receptor number following acute insulin treatment in vitro is due to an insulin receptor recycling pathway, possibly involving lysosomes and/or the Golgi apparatus.
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245
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Van Vleet JF, Ferrans VJ. Ultrastructural alterations in the atrial myocardium of pigs with acute monensin toxicosis. THE AMERICAN JOURNAL OF PATHOLOGY 1984; 114:367-79. [PMID: 6696048 PMCID: PMC1900426] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Monensin, A Na+-selective carboxylic ionophore, produces left atrial damage in pigs given toxic doses. Eight weanling pigs were given mycelial monensin orally (40 mg/kg body weight) and were killed on days 1, 2, 4, and 16 (two animals at each time interval) for ultrastructural study of the left atrial lesions. On days 1-4, extensive necrosis with contraction bands was present. Rapid macrophagic invasion and phagocytosis of sarcoplasmic debris was seen on days 2 and 4. Missing necrotic myocytes were outlined by persistent "tubes" of external laminas. In some surviving myocytes, sublethal injury was evident on day 1 by mitochondria with condensed conformation and on days 2, 4, and 16 by moderate to marked myofibrillar lysis and sarcoplasmic vacuolation. Monensin cardiotoxicity in pigs constitutes a unique example of selective injury to atrial myocardium.
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246
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Synthesis, processing, and secretion of the core-specific lectin by rat hepatocytes and hepatoma cells. J Biol Chem 1984. [DOI: 10.1016/s0021-9258(17)43185-1] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
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247
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Miskimins WK, Shimizu N. Uptake of epidermal growth factor into a lysosomal enzyme-deficient organelle: correlation with cell's mitogenic response and evidence for ubiquitous existence in fibroblasts. J Cell Physiol 1984; 118:305-16. [PMID: 6607926 DOI: 10.1002/jcp.1041180314] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
The internalization process following cell surface receptor binding by epidermal growth factor (EGF) was studied. It was found that EGF is taken up into a dense, membranous organelle. This organelle is deficient in lysosomal enzyme activity and is biochemically dissimilar to the major lysosomal fraction. The uptake of EGF by this organelle was demonstrated in three different cell types representing three different species. Each of these cell types is highly responsive to the mitogenic action of EGF. These results indicate that EGF is endocytosed and delivered to a dense, possibly nonlysosomal, organelle which is ubiquitous in fibroblasts. Furthermore, we demonstrate a close, positive correlation between EGF uptake into this fraction and the ability of cells to respond to the mitogen. A negative relationship between uptake into the subcellular fraction containing lysosomal enzymes and EGF-stimulated DNA synthesis was observed. Using numerous incubation conditions no exceptions to the correlation between EFG uptake into the lysosomal enzyme-deficient fraction and EGF-induced DNA synthesis were observed. These results suggest a role for this dense organelle in the production of a mitogenic signal.
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248
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Emilsson A, Sundler R. Differential activation of phosphatidylinositol deacylation and a pathway via diphosphoinositide in macrophages responding to zymosan and ionophore A23187. J Biol Chem 1984. [DOI: 10.1016/s0021-9258(17)43267-4] [Citation(s) in RCA: 91] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
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249
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Eskild W, Berg T. Endocytosis of formaldehyde-denatured serum albumin by nonparenchymal liver cells in vitro. BIOCHIMICA ET BIOPHYSICA ACTA 1984; 803:63-70. [PMID: 6696954 DOI: 10.1016/0167-4889(84)90055-7] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
The uptake and degradation of 125I-labeled formaldehyde-denatured serum albumin in nonparenchymal rat liver cells were studied in vitro. Nonparenchymal cells bound formaldehyde-denatured serum albumin at two types of binding site, one with a high affinity and one a low affinity. The number of high affinity binding sites was approx. 10(5) per cell and the association constant, Ka 10(8) M-1. Inhibition of protein synthesis with cycloheximide did not affect the uptake and degradation of formaldehyde-denatured serum albumin suggesting reutilization of the binding sites. The presence of monensin-reduced uptake and degradation to less than 10% of control values. Pronase treatment of nonparenchymal liver cells completely abolished the uptake and degradation of the ligand. The uptake mechanism was not specific for formaldehyde-denatured serum albumin. Unlabeled acetylated, as well as malondialdehyde treated, serum albumin reduced the uptake of 125I-labeled formaldehyde-denatured serum albumin as effectively as unlabeled formaldehyde-denatured serum albumin itself.
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250
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Vladutiu GD. Transport and processing of beta-hexosaminidase in normal and mucolipidosis-II cultured fibroblasts. Effect of monensin and nigericin. Biochem J 1984; 218:261-8. [PMID: 6231921 PMCID: PMC1153331 DOI: 10.1042/bj2180261] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
The univalent-cation ionophores monensin (4.0 microM) and nigericin (0.5 microM) inhibited the abnormal excretion of beta-hexosaminidase from mucolipidosis-II cultured fibroblasts by 62 and 76% respectively, with a corresponding intracellular accumulation of the enzyme. As shown by lectin binding, the enzyme which accumulated in monensin-treated cells did not contain galactose residues, whereas the corresponding enzyme from nigericin-treated cells was galactosylated. The results suggest that monensin acts at an early point in the process of hydrolase glycosylation, and nigericin acts later, both presumably within the Golgi region, allowing the accumulation of different glycosylated forms of the enzyme. The intra- and extra-cellular distribution of beta-hexosaminidase in ionophore-treated normal cells was essentially unchanged, whereas concanavalin A precipitability of excreted enzyme was increased and its ability to be taken up by deficient fibroblasts was decreased. The bivalent-cation ionophore A23187 (1 microM) reduced beta-hexosaminidase excretion from mucolipidosis-II cells by 82% and by 96% when used with EGTA (1 mM). However, there was no intracellular accumulation of enzyme, suggesting that the effect of this ionophore was restricted to the inhibition of synthesis. It therefore appears that the actual transport of beta-hexosaminidase in mucolipidosis-II cells is affected by univalent-cation ionophores in a selective manner. These findings suggest that individual ionophores could be used to identify the sites of hydrolase oligosaccharide processing in the Golgi region by causing intermediate glycosylated forms of the transported hydrolase to accumulate in a specific Golgi compartment preceding the blocking site of the ionophore.
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