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  • 1
    Electronic Resource
    Electronic Resource
    Transition metal chelator TPEN counteracts phorbol ester-induced actin cytoskeletal disruption in C6 rat glioma cells without inhibiting activation or translocation of protein kinase C (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 158 (1994), S. 337-346 
    Details
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Phorbol ester-induced reorganization of the actin cytoskeleton was investigated in C6 rat glioma cells. Observations by fluorescence microscopy and photoelectron microscopy indicated that pretreatment with the transition metal chelator N,N,N',N'-tetrakis(2-pyridylmethyl)ethylenediamine (TPEN) for 1-2 h at 50 μM reduced the sensitivity of the actin cytoskeleton to disruption by the subsequent addition of 200 nM phorbol myristate acetate (PMA). The protective effect of TPEN was eliminated by adding back Zn2+ prior to PMA addition, implicating chelation of metal ions as the mechanism of action of TPEN. C6 cells exposed to PMA experience potent activation of protein kinase C (PKC) and substantial redistribution of the kinase from a soluble to a particulate cellular fraction (translocation). TPEN pretreatment did not block PKC translocation in PMA-exposed cells. By two-dimensional gel analysis, TPEN also did not reduce, but rather slightly increased, the PMA-stimulated phosphorylation of the acidic 80 kDa endogenous PKC substrate, as well as two other proteins at 18 kDa and 50 kDa. In contrast, TPEN significantly suppressed phosphorylation of a 20 kDa protein, both in cells treated with TPEN only and in TPEN-pretreated PMA-exposed cells. The results indicate that the ability of TPEN to protect against PKC-mediated actin cytoskeletal disruption is not due to either a block of PKC translocation or to general inhibition of PKC activity. Rather, the action of TPEN is more selective and probably involves chelation of Zn2+ at a critical Zn2+ -dependent phosphorylation step downstream from the initial tumor promoter--induced effects on PKC. © 1994 Wiley-Liss, Inc.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1041580216
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  • 2
    Electronic Resource
    Electronic Resource
    Foreword (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Microscopy Research and Technique 25 (1993), S. 353-353 
    Details
    ISSN: 1059-910X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jemt.1070250502
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  • 3
    Electronic Resource
    Electronic Resource
    Polymer substrates for controlled biological interactions (1994)
    New York, N.Y. : Wiley-Blackwell
    Journal of Cellular Biochemistry 56 (1994), S. 155-161 
    Details
    ISSN: 0730-2312
    Keywords: plyetheylene oxide ; receptor-mediated interactions ; biomaterials ; tissue regeneration ; ligands ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: The identification of a myriad of small peptide and carbohydrate lieands recognizes by cell surface receptors has generated enthusiasm for the use of these ligands of components of biomaterials dor controlling cellular interactions. Achiening control of cell interaations via ligand modification of materials also refquires that nonspecific interactions of cells with these materials due to supface adsorption of biological macromolecules is milimized. Polyetylene oxide (PEO) exhibits extraordinary inertness toward most biological macromlecules and is thus receiving increasing attention as a component of new materials for controlling cell behavior. Both surface and bulk modifications with PEO are being applied to develop a range of bland substrate material as vehicles for ligand immobilization.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcb.240560206
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  • 4
    Electronic Resource
    Electronic Resource
    Phosphatidylinositol-specific phospholipase C From Bacillus cereus: Improved purification, amino acid composition, and amino-terminal sequence (1989)
    New York, N.Y. : Wiley-Blackwell
    Journal of Cellular Biochemistry 39 (1989), S. 315-325 
    Details
    ISSN: 0730-2312
    Keywords: N-terminal sequence ; bacterial phospholipase ; structure ; isolation ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Phosphatidylinositol-specific phospholipase C was purified in a 27% yield from the culture medium of Bacillus cereus by a combination of ammonium sulfate precipitation and ion-exchange and hydrophobic interaction chromatography. The purified enzyme was free of other phospholipase C-type activities and exhibited a high specific activity of approximately 1,300 units/mg. Amino acid composition analysis and sodium dodecyl sulfate-polyacrylamide gel electrophoresis indicated a molecular weight of about 35 kDa. The sequence of the first 29 N-terminal amino acids was also determined.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcb.240390311
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  • 5
    Electronic Resource
    Electronic Resource
    Partial isolation from intact cells of a cell surface-exposed lysophosphatidylinositol-phospholipase C (1997)
    New York, N.Y. : Wiley-Blackwell
    Journal of Cellular Biochemistry 65 (1997), S. 550-564 
    Details
    ISSN: 0730-2312
    Keywords: ecto-PLC ; ecto-enzyme ; phosphoinositide-specific phospholipase C ; cell surface enzyme ; lyso-PI-cleaving PLC ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: A novel cell surface phosphoinositide-cleaving phospholipase C (ecto-PLC) activity was isolated from cultured cells by exploiting its presumed external exposure. Biotinylation of intact cells followed by solubilization of the biotinylated proteins from a membrane fraction and recovery onto immobilized-avidin beads, allowed assay of this cell surface enzyme activity apart from the background of the substantial family of intracellular PLCs. Several cell lines of differing ecto-PLC expression were examined as well as cells stably transfected to overexpress the glycosylphosphatidylinositol (GPI)-anchored protein human placental alkaline phosphatase (PLAP) as a cell surface enzyme marker. The resulting bead preparations from ecto-PLC positive cells possessed calcium-dependent PLC activity with preference for lysophosphatidylinositol (lysoPI) rather than phosphatidylinositol (PI). The function of ecto-PLC of intact cells evidently is not to release GPI-anchored proteins at the cell surface, as no detectable Ca2+-dependent release of overexpressed PLAP from ecto-PLC-positive cells was observed. To investigate the cell surface linkage of the ecto-PLC itself, intact cells were treated with bacterial PI-PLC to cleave simple GPI anchors, but no decrease in ecto-PLC activity was observed. High ionic strength washes of biotinylated membranes prior to the generation of bead preparations did not substantially reduce the lysoPI-PLC activity. The results verify that the ecto-PLC is truly cell surface-exposed, and unlike other members of the PLC family that are thought to be peripheral membrane proteins, this novel lysoPI-PLC is most likely a true membrane protein. J. Cell. Biochem. 65:550-564. © 1997 Wiley-Liss Inc.
    Additional Material: 6 Ill.
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  • 6
    Electronic Resource
    Electronic Resource
    A high level of cell surface phosphatidylinositol-specific phospholipase C activity is characteristic of growth-arrested 3T3 fibroblasts but not of transformed variants (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 151 (1992), S. 613-622 
    Details
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Confluent monolayers of four contact-inhibited mouse fibroblast lines (Swiss 3T3, Balb/c 3T3, NIH 3T3, and C3H10T1/2) were found to have substantial levels of a cell surface phosphatidylinositol-specific phospholipase C (ecto-PLC). In contrast, confluent cultures of virally, chemically, or spontaneously transformed variants derived from these cell lines expressed undetectable or negligible levels of this enzyme activity. A simple and rapid assay, using lysophosphatidylinositol radio-labeled in the inositol group ([3H]-lysoPI) as the substrate was developed to provide a quantitative measure of the phospholipase C activity present at the external cell surface. For cells testing positive for ecto-PLC activity, rapid uptake of [3H]-lysoPI is accompanied by the simultaneous appearance of [3H]-inositol phosphate in the external medium. Confluent monolayers of the four mouse fibroblast lines exhibiting density-dependent growth inhibition had levels of ecto-PLC activity in the range of 50-800 pmol/min/106 cells (i.e., about 20-50 times greater than the activity observed for the transformed variants). The expression of ecto-PLC activity at the cell surface of the Swiss or Balb/c cells was dependent on the state of cell proliferation. Cultures which had become quiescent through attainment of confluence displayed a tenfold increased activity over that of subconfluent, growing cultures of these cells. Similarly, subconfluent Swiss 3T3 cells which had become quiescent following exposure to low serum conditions also showed increased activity. These results indicate that there may exist a correlation between the control of cell proliferation in contact-inhibited mouse fibroblasts and the expression of inositol phospholipid-specific phospholipase C activity at the external cell surface. © 1992 Wiley-Liss, Inc.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1041510322
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  • 7
    Electronic Resource
    Electronic Resource
    Development of a serum-free medium which supports the long-term growth of human and nonhuman primate lymphoid cells (1983)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 115 (1983), S. 191-198 
    Details
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The ability to grow lymphoid cells in serum-free media affords the advantage of separately analyzing those components found to be involved in proliferation and differentiation. Iscove's medium (IMDM) supplemented with bovine serum albumin or casein, cholesterol, ferrous chloride, insulin, β-mercaptoethanol, L-α-phosphatidylcholine, and transferrin supported the long-term proliferation of a gibbon ape lymphoma T-cell line, MLA144. These cells continue to produce Interleukin 2 (IL-2, T-cell growth factor) constitutively in the serum-free medium. IL-2-dependent human T cells initiated and maintained in culture in serum-free medium containing IL-2 have continued to replicate for over 3 months with two population doublings every 3 to 4 days. A normal, IL-2-dependent marmoset T-cell line, OH-1, also proliferated on the serum-free medium when supplemented with IL-2. Several established primate B-cell lines which do not require IL-2 for growth were able to proliferate in the serum-free medium. These B-cell lines included B95-8, an Epstein-Barr virus (EBV)-transformed marmoset cell line, HuCo/R-H, a human cord B-lymphocyte line transformed with EBV, and Namalwa, an EBV-positive B-cell line established from a Burkitt's lymphoma. B95-8 cells grown on serum-free medium showed high levels of EBV antigen-positive cells after induction with 12-O-tetradecanoyl-phorbol-13-acetate (TPA).
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1041150214
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  • 8
    Electronic Resource
    Electronic Resource
    Protein kinase C inhibitor H-7 alters the actin cytoskeleton of cultured cells (1989)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 141 (1989), S. 74-84 
    Details
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The effects of the protein kinase C inhibitor H-7 on the actin cytoskeleton of cultured cells (Swiss 3T3 and PTK2) are described. As documented by fluorescence microscopy and the higher-resolution technique of photoelectron microscopy, the effects are rapid and dramatic; exposure to 30 μM H-7 in culture medium for less than 6 min is sufficient to induce a significant reduction in the numbers and thickness of actin microfilament bundles and alterations in the morphology of cell-cell boundaries in PTK2 cells. One-hour exposure to 30 μM H-7 results in nearly complete depletion of normal actin microfilament bundles from all of the cell types examined, without dramatic changes in overall cell shape. The intermediate filament and microtubule cytoskeletal networks did not appear to be affected to any extent over the times and doses examined. Forty-five minutes of exposure of Swiss 3T3 cells to 200 μM of either HA1004 (which is comparable to H-7 with respect to inhibition of cyclic nucleotide dependent kinases) or to the protein kinase C inhibitor sangivamycin did not induce the actin alterations characteristic of H-7. In addition, depletion of protein kinase C from Swiss 3T3 cells by means of phorbol ester-induced down-regulation did not prevent the effects of H-7 on the actin cytoskeleton. These results demonstrate that the protein kinase C inhibitor H-7 has a specific and rapid effect on the actin cytoskeleton, and furthermore H-7 may have biochemical effects beyond those mediated by inhibition of protein kinase C or the cyclic nucleotide dependent kinases.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1041410112
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