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  • transepithelial electrical resistance  (2)
  • HL 60 and U 937 cells  (1)
  • 1
    Electronic Resource
    Electronic Resource
    Studies with wortmannin and cytochalasins suggest a pivotal role of phosphatidylinositols in the regulation of tight junction integrity (1996)
    Springer
    Bioscience reports 16 (1996), S. 265-272 
    Details
    ISSN: 1573-4935
    Keywords: Wortmannin ; cytochalasin B ; dihydrocytochalasin B ; MDCK-I cells ; transepithelial electrical resistance ; F-actin ; phosphatidylinositols
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Wortmannin, a selective inhibitor of phosphatidylinositol 3-kinase (P13K), was found to give a dose and time-dependent, bimodal effect-initial increase, followed by decrease on the tight junction integrity of MDCK-1 monolayers, as assessed by electrical resistance measurement of the epithelia. Moreover, dihydrocytochalasin B inhibited the wortmannin-induced alteration, whereas cytochalasin B had a negligible influence on the wortmannin effect. Wortmannin was also found to cause changes in the cytoskeleton structure. These alterations were also seen when wortmannin was combined with cytochalasin B. However, in accordance with the electrical resistance measurements, dihydrocytochalasin B was able to abolish wortmannin-induced filamentous (F-) actin changes. These findings suggest that the P13K, phosphatidylinositols, and filamentous actin rearrangements, in combination, play an important role in the modulation of the junctional integrity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01207340
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  • 2
    Electronic Resource
    Electronic Resource
    Modulation of the junctional integrity by low or high concentrations of cytochalasin B and dihydrocytochalasin B in associated with distinct changes in F-actin and ZO-1 (1996)
    Springer
    Bioscience reports 16 (1996), S. 313-326 
    Details
    ISSN: 1573-4935
    Keywords: cytochalasin B ; dihydrocytochalasin B, MDCK-I cells ; transepithelial electrical resistance ; ZO-1 ; F-actin ; tight junction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract In a study of Necturus gallbladder epithelium Benzel et al. (Benzel et al., 1980) found that low (0.2–1.2 μM) and higher concentrations (1.5 μM and more) of cytochalasin B (CB) caused an increase and decrease in the transepithelial electrical resistance (TER), respectively. Moreover, there were slight changes in the height and complexicity of tight junction (TJ) strands, as visualized by freeze-fracture and freeze-etching. To elucidate the mechanisms of these findings, we first demonstrated that the effect is also present in monolayers of Madin-Darby Canine Kidney strain I (MDCK-I) cells. Thus, a low concentration (0.1 ng/ml) cytochalasin B (CB) strengthened the permeability barrier, as evidenced quantitatively by increases in TER on transepithelial electrical measurements. Furthermore, indirect immunofluorescence and confocal microscopy demonstrated that this effect was paralleled with an accumulation of F-actin and the tight junction marker protein, ZO-1, at the level of TJ. Equimolar concentrations of dihydrocytochalasin B (dhCB), on the other hand, did not lead to a tightening of the epithelium. Confirming previous studies, there was a general decrease in epithelial resistance after treatment with high concentrations (1 μg/ml) of CB and dhCB, which was accompanied by distinct changes in the F-actin network and distribution of ZO-1. We speculate that the divergent effects of CB and dhCB on the F-actin and ZO-1 organization might be due to specific effects on the transport of monosaccharides across the plasma membrane, or that CB and dhCB in distinct ways involve the turnover of phosphatidylinositols in the membrane, thereby modulating junctional permeability and F-actin structure.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01855015
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  • 3
    Electronic Resource
    Electronic Resource
    Development of distinct clonal patterns of carbohydrate-binding activity in human promyelocytic HL 60 cells and histiocytic U 937 cells during DMSO-or PMA-induced differentiation (1988)
    Springer
    Glycoconjugate journal 5 (1988), S. 271-281 
    Details
    ISSN: 1573-4986
    Keywords: HL 60 and U 937 cells ; phagocytosis ; IgG ; complement ; glycolipid ; liposome binding ; fluorescence microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Increased ability to recognize carbohydrate structures on particles was observed in promyelocytic HL 60 cells and histiocytic U 937 cells during differentiation inducedin vitro with dimethylsulfoxide (DMSO) or phorbol myristate acetate (PMA). The size of the cells and increased capacity to bind and ingest IgG-or complement-coated yeast particles were used as indicators of phagocytic maturation. Carbohydrate affinities were assessed by the binding of glycolipid-containing liposomes displaying mannose, galactose, lactose,N-acetylgalactosamine, fucose, inositol, or ganglioside residues. With DMSO, HL 60 cells showed greater affinity for mannose and ganglioside residues, and with PMA also for fucosyl ligands. U 937 cells displayed a slightly different pattern; mannose binding was present before induction and by DMSO affinity was clearly augmented for galactose, fucose, ganglioside and inositol residues. With PMA these effects were smaller except for increased binding of lactosyl liposomes. Subclones of cells derived from U 937 (Cl 1, Cl 2 and Cl 3) appeared more mature already in the absence of inducing agent, and the lectin activity was barely affected by DMSO or PMA. Incidentally, Cl 1 lacked mannose affinity, which was fully expressed in Cl 2. With respect to inositol and ganglioside residues the reverse pattern was observed. In conclusion, DMSO- or PMA-mediated maturation in HL 60 and U 937 cells is accompanied by increased carbohydrate binding similar to what has been found in mature macrophages and granulocytes, indicating that these cellular systems can be used for further assessment of the molecular origin of lectin-like membrane components in phagocytic cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01049087
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    Paper (German National Licenses)
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