Browsing by Author "KOENIG, CS"

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    A LIPID-ANCHORED HEPARAN-SULFATE PROTEOGLYCAN IS PRESENT IN THE SURFACE OF DIFFERENTIATED SKELETAL-MUSCLE CELLS - ISOLATION AND BIOCHEMICAL-CHARACTERIZATION
    (1993) CAMPOS, A; NUNEZ, R; KOENIG, CS; CAREY, DJ; BRANDAN, E
    We have investigated the presence of hydrophobic membrane-associated heparan sulfate proteoglycans (HSPG) on the cell surface of differentiated skeletal muscle cells. A HSPG releasable by incubation with a phosphatidylinositol-specific phospholipase c (PtdIns-PLC) was obtained. HSPG were also isolated from Triton X-100 extracts of the cells. The hydrodynamic characteristics of the PtdIns-PLC-releasable and detergent-extracted HSPG were indistinguishable. SDS/PAGE analysis of the PtdIns-PLC-releasable HSPG indicated a molecular mass of 250 kDa. Analysis of proteins immunoprecipitated by specific antibodies against a HSPG isolated from Schwann cells demonstrated that the antisera precipitated an intact HSPG that was present in the pool of proteins released by PtdIns-PLC and by Triton X-100 from [S-35]sulfate labeled cells. Nitrous acid degradation of the immunoprecipitated proteins released by PtdIns-PLC from [S-35]methionine labeled cells produced a single 67-kDa core protein. Analysis of hydrophobicity of the purified HSPG revealed that only the HSPG obtained from the detergent extract were able to be incorporated into the liposomes whereas the PtdIns-PLC-released HSPG was not.
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    ACTIN AND MYOSIN IN OXYNTIC CELL - GELATION AND CONTRACTION OF CRUDE EXTRACTS INVITRO
    (1981) KOENIG, CS; DABIKE, M; VIAL, JD
    Extracts prepared from purified toad [Bufo spinulosus] oxyntic cells undergo temperature-dependent, cytochalasin B (CB)-sensitive gelation. In the presence of ATP, the interaction between gelled actin and myosin produces a contracted gel. Such association ceases spontaneously after shrinkage is completed. A stable myosin-actin interaction takes place in the absence of ATP, but no contraction of the gel is observed. A correlation between this actomyosin system present in oxyntic cells and the high mobility of the secretory pole, resulting in the changes in shape observed during the onset of HCl secretion, is proposed.
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    ASSOCIATION OF CANALICULAR MEMBRANE ENZYMES WITH BILE-ACID MICELLES AND LIPID AGGREGATES IN HUMAN AND RAT BILE
    (ELSEVIER SCIENCE BV, 1995) ACCATINO, L; PIZARRO, M; SOLIS, N; KOENIG, CS
    This study was undertaken to gain insights into the characteristics of the polymolecular association between canalicular membrane enzymes, bile acids, cholesterol and phospholipids in bile and into the cellular mechanisms whereby the enzymes are secreted into bile. With this purpose, we studied the distribution of bile acids, cholesterol, phospholipids, proteins and representative canalicular membrane enzymes (alkaline phosphatase, 5'-nucleotidase and gamma-glutamyl transpeptidase), which can be considered specific marker constituents, in bile fractions enriched in phospholipid-cholesterol lamellar structures (multilamellar and unilamellar vesicles) and bile acid-mixed micelles. These fractions were isolated by ultracentrifugation from human hepatic bile, normal rat bile and bile of rats treated with diosgenin, a steroid that induces a marked increase in biliary cholesterol secretion, and were characterized by density, lipid composition and transmission electron microscopy. These studies demonstrate that alkaline phosphatase, T-nucleotidase and gamma-glutamyl transpeptidase are secreted into both human and rat bile where they are preferentially associated with bile acid-mixed micelles, suggesting a role for bile acids in both release of these enzymes and lipids from the canalicular membrane and solubilization in bile. In addition, heterogeneous association of these enzymes with nonmicellar, lamellar structures in human and rat bile is consistent with the hypothesis that processes independent of the detergent effects of bile acids might also result in the release of specific intrinsic membrane proteins into bile.
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    CYTOCHEMICAL STUDY OF DISTRIBUTION OF ADENOSINE-TRIPHOSPHATASE IN PANCREAS OF DOG
    (1976) KOENIG, CS; SANTELICES, LC; VIAL, JD
    Dog pancreatic tissue, incubated in a modified Wachstein-Meisel medium, showed 2 different ATPase activities. One of them was located at the apical border of the cells lining the intralobular ducts and of the centroacinar cells and was stimulated by HCO3-, depressed by SCN- and OCN- and completely abolished by CN-. The other was located at the intracellular clefts of the epithelium lining the interlobular ducts and was stimulated by Mg2+. These findings correlated well with the results of incubation of homogenates of fresh and fixed tissues. Their significance with respect to the role of different segments of the duct system in the formation of the pancreatic juice was discussed.
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    DISTRIBUTION OF INTERMEDIATE FILAMENTS IN AMPHIBIAN OXYNTIC CELLS - BIOCHEMICAL AND IMMUNOLOGICAL CHARACTERIZATION
    (1981) DABIKE, M; KOENIG, CS; VIAL, JD
    Intermediate filaments of toad oxyntic cells were isolated and analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The major proteins of the residue were identified as actin and a 51,000 dalton polypeptide. Immunological crossreactivity between toad oxyntic cell intermediate filament components and antiprekeratin was shown by double immunodiffusion tests and indirect immunofluorescence. The immunofluorescent decoration of oxyntic cells and the EM images are coincident in locating the intermediate filaments mainly at the cortical and perinuclear basal zones. The cortical zone appears especially rich in prekeratin-like material at its adluminal 3rd. This results in a cup-like structure that encloses the cell portion occupied by the tubulovesicular system, which does not contain intermediate filaments. The translocation of membranes occurring during the secretory cycle of the oxyntic cell was attributed to a system of contractile proteins. The disposition of the prekeratin-like material suggests a role for intermediate filaments in the generation of movement produced by actin and myosin interaction, by providing a fixed plane for the anchoring of actin microfilaments.
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    DISTRIBUTION OF INTERMEDIATE FILAMENTS IN EPITHELIAL-CELLS OF THE AMPHIBIAN URINARY-BLADDER - AN IMMUNOFLUORESCENCE STUDY
    (1989) DABIKE, M; MUNIZAGA, A; KOENIG, CS
    The distribution of intermediate filaments in toad and frog urinary bladder was studied on frozen sections by indirect immunofluorescence microscopy using specific antiprekeratin antibodies. Our results show that in both species, epithelial cells lining the urinary bladder are very rich in cytokeratin, organized as a filamentous network. In granular cells, the most abundant cells facing the urinary lumen, vasopressin promotes fusion of the membranous tubular structures located in the luminal cytoplasm with the apical cell membrane. A role for intermediate filaments in the membrane rearrangements induced by vasopressin in these cells, is proposed.
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    FILAMIN AND MYOSIN ARE PRESENT IN THE SECRETORY POLE OF AMPHIBIAN OXYNTIC CELLS - AN IMMUNOFLUORESCENCE STUDY
    (1986) DABIKE, M; MUNIZAGA, A; KOENIG, CS
    The presence of a filamin-like protein in oxyntic cells was established by indirect immunofluorescence microscopy. The location of this protein and myosin was studied, using specific antibodies, on frozen sections and isolated cells. Antifilamin and antimyosin reacted strongly with the luminal cytoplasm of the cells. In resting oxyntic cells, filamin appeared organized as a reticular sheet in the apical border. In stimulated cells, the apical concentration of filamin decreased, and its distribution appeared rather diffuse. This immunoreactive band seems to correspond to the cytoplasmic region where actin microfilaments have been described previously. The changes in the apical concentration of filamin, induced by the onset of HCl secretion, correlate with the ultrastructural reorganization of the actin network that occurs during the secretory cycle. The use of antimyosin antibodies showed that this protein forms an apical peripheral ring in both resting and stimulated cells. No clear changes in the distribution of myosin, in relation to secretion, could be established by immunofluorescence. These findings, taken together with published morphological and biochemical evidence, suggest that a three-dimensional network composed of actin and filamin is present in the secretory pole of resting amphibian oxyntic cells. The hypothesis that gel-sol transitions play a role in the structural reorganization of the secretory pole of these cells is supported by the present results.
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    INTERMEDIATE FILAMENTS OF THE CYTOSKELETON IN GLANDULAR CELLS OF THE RAT FUNDIC MUCOSA - IMMUNOFLUORESCENCE AND ELECTRON-MICROSCOPY STUDY
    (1983) DABIKE, M; KOENIG, CS
    The organization of intermediate filaments (IF) in cells of the rat fundic mucosa was studied by EM and immunofluorescence microscopy using specific antiprekeratin antibodies on frozen sections and isolated cells. Mucous cells lining the gastric surface and the gastric pits, which appeared strongly decorated, are probably the most rich in IF. These cells displayed coarse bundles of IF oriented in all directions as well as desmosome-attached tonofibrils. Mucous neck cells contained fewer bundles of IF located preferentially toward the apical region. Zymogen cells showed a strong staining along the contour of the luminal border, together with a faint decoration of a fine meshwork extending throughout the cytoplasm. A poorly defined fibrillar cortex present underneath the secretory plasma membrane and sparse bundles of IF among the elements of the rough endoplasmic reticulum were seen in thin sections. In contrast, parietal cells appeared brightly stained and the prekeratin-like material formed a cortical polygonal meshwork especially visible in isolated cells. A developed system of IF formed by conspicuous bundles located underneath the secretory canaliculi, among the mitochondria and in the vicinity of the basal plasma membrane, was observed in the EM.
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    ISOLATION OF PEROXISOMES FROM FROZEN HUMAN LIVER SAMPLES
    (1992) ALVAREZ, A; HIDALGO, U; KAWADA, ME; MUNIZAGA, A; ZUNIGA, A; IBANEZ, L; KOENIG, CS; SANTOS, MJ
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    QUANTITATIVE SUBCELLULAR STUDY OF APICAL POLE MEMBRANES FROM CHICKEN OXYNTIC CELLS IN RESTING AND HCL SECRETORY STATE
    (1987) KOENIG, CS; DABIKE, M; BRONFMAN, M
    Vertebrate oxyntic cells, responsible for gastric HCl production, undergo a remarkable morphological reorganization in relation to their secretory cycle. In resting state, the luminal surface of the cells is smooth; a peculiar system of endocellular membranes, the tubular system, occupies the luminal cytoplasm. Actin filaments frame a cortical network between the tubular system and the luminal plasma membrane. With the onset of HCl secretion, the tubular system becomes incorporated into the luminal plasma membrane. Villous processes containing microfilaments fill the secretory surface. This morphological reorganization of membranes and cytoskeletal matrix could regulate HCl secretion by translocation of membranes containing the proton pump from the endocellular compartment to the secretory surface. In this paper, we describe the isolation of membranes that selectively belong to the tubular system or to the cytoplasmic processes of the secretory surface of chicken oxyntic cells. Chicken oxyntic cells are the main cellular component of the proventricular glands. A resting state was obtained after cimetidine treatment, whereas the HCl-secretory state was induced by histamine. We present a comparative analysis of resting and stimulated chicken gastric glands by quantitative subcellular fractionation. The HCl secretory state was related to specific modifications in membrane fractions derived from the secretory pole of oxyntic cells. Morphological and functional reorganization of oxyntic cells was closely correlated with changes in: the sedimentation pattern of the marker enzyme of the apical pole membrane (K-NPPase), the total activity of K-NPPase and nonmitochondrial Mg-ATPase, the valinomycin dependence of K-ATPase, and polypeptides that cosediment in purified membrane fractions. Changes in the distribution pattern of K-NPPase after fractionation of histamine-stimulated glands were consistent with the replacement of the small vesicles typical of resting glands by dense membrane profiles, analogous to the luminal processes of stimulated oxyntic cells. SDS-PAGE showed that, in purified membrane fractions of stimulated glands, the concentration of 28-, 43-, and 200-kDa polypeptides increased while that of 95- and 250-kD polypeptides decreased. The present results define the tubular system of oxyntic cells as an organelle with properties different from those of endoplasmic reticulum, mitochondria, and plasma membrane. The biochemical and physicochemical properties of this membraneous system changed when the organization of the membranes and the cytoskeletal matrix of the apical pole was modified by the onset of HCl secretion.
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    REDISTRIBUTION OF MEMBRANES AND CYTOSKELETAL PROTEINS IN CHICKEN OXYNTIC CELLS DURING THE HCL SECRETORY CYCLE - ULTRASTRUCTURAL AND IMMUNOFLUORESCENCE STUDY
    (1990) KOENIG, CS; DABIKE, M
    Changes in ultrastructure and cytoskeletal organization by avian oxyntic cells, at the onset of HCl secretion, were analysed. Cells in resting state, induced by fasting and cimetidine, were compared with histamine stimulated secreting cells. Ultrastructural studies were done by transmission electron microscopy; the distribution of prekeratin, myosin, and filamin-like protein, by immunofluorescence; and that of F-actin using FITC-phalloidin. Resting cells show short pericellular clefts. These are increasingly deepended in secreted cells by a reorganization of the lateral cell borders involving displacemnt of the junctional complexes toward the cell base and incorporation of the tubular system to the luminal plasma membrane. In secreting cells, the processes of the secretory surface are concentrated in a pericellular groove. Histamine stimulation induces a drastic redistribution of cytoskeletal proteins. In chicken oxyntic cells, in addition to the F-actin cytoskeleton associated with the membranes of the secretory surface, there is a cytoskeletal ring containing F-actin, myosin, and a filamin-like protein, located at the level of the junctional complexes. In resting cells, filaments and masses of cytoskeletal matrix are associated with the zonula adherens. In secreting cells, the junctional complexes maintain their association with the filamentous ring, while the amorphous matrix is replaced by microfilaments that support the processes of the luminal surface. Intermediate filaments form a peripheral ring probably associated with the zonula adherens, and project from the ring toward the cell cytoplasm. Thus, with the onset of HCl secretion, the apical cytoskeletal ring of resting cells displaces toward the cell base. A role for this cytoskeletal ring in the changes in shape parallel to HCl secretion is discussed.