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  • 1
    Electronic Resource
    Electronic Resource
    Effect of cell density on energy-dependent calcium uptake by Balb/c 3T3 membranes is independent of protein synthesis and attachment to substratum (1979)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 101 (1979), S. 109-116 
    Details
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Membranes isolated from subconfluent cultures of Balb/c 3T3 cells have low energy-dependent calcium uptake activity. Replating confluent cells at low density results in a prompt fall of energy-dependent calcium uptake by membrane fractions. The level to which uptake activity falls is a function of the density at which the cells are plated (Moore and Pastan, '77b). To determine if regulation of energy-dependent uptake of calcium by membrane fractions is dependent upon attachment to a substrate and to further characterize conditions that regulate the process, we examined calcium uptake activity of membranes isolated from cells in suspension. With cells in suspension energy-dependent calcium uptake activity of isolated membranes falls promptly if cells are diluted to a low density (〈105 cells/ml) and is a function of cell density. When cells in suspension at low cell densities are concentrated to high cell densities (〉2 X 106 cells/ml), calcium uptake activity of the isolated membrane fraction is increased as a function of cell density. These changes of membrane calcium uptake activity occur promptly and do not require protein synthesis.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1041010113
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  • 2
    Electronic Resource
    Electronic Resource
    A calcium requirement for movement of cultured cells (1979)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 101 (1979), S. 101-108 
    Details
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: When calcium is removed from culture medium, motility of cultured cells is decreased. The effect is rapid, reversible and pronounced. Decreased motility is observed with normal mouse Balb/c 3T3 cells, mouse L929 cells, rat kidney fibroblasts and chick embryo fibroblasts. The calcium dependence of movement can be observed both with individual cells and with the movement of the margin of a monolayer into a wound. Magnesium will not substitute for calcium to maintain motility. Strontium will substitute, but is not as effective as calcium for maintaining cell movement. Low concentrations of the divalent cation ionophore A23187 (0.5-1 μm) partially reverse the reduced migration observed at low calcium concentrations. These results are consistent with the hypothesis that movement of non-muscle cells occurs through mechanisms similar to those important in the contraction of muscle.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1041010112
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  • 3
    Electronic Resource
    Electronic Resource
    Rous sarcoma virus transformed cells are resistant to cyclic AMP (1982)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 111 (1982), S. 42-48 
    Details
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: A nontransformed line of Chinese hamster ovary (CHO) cells (Pollard and Stanners, 1979) has been transformed by the Schmidt-Ruppin subgroup D strain of Rous sarcoma virus (SR-RSV). SR-RSV transformed CHO cells are shown to differ from spontaneously transformed cells in that the virally transformed cells are more resistant to growth inhibition or changes in cell shape by 8-Br-cyclic AMP or cholera toxin. SR-RSV transformed rat (NRK) cells also have a reduced sensitivity to growth inhibition by 8-Br-cyclic AMP. Cyclic AMP-dependent protein kinase was examined in SR-RSV transformed CHO cells, but no differences in enzyme level, activation by cyclic AMP, chromatographic behavior, or its ability to phosphorylate endogenous proteins in whole cells could be detected. It is concluded that transformation of CHO and NRK cells by SR-RSV alters the cells in a manner different from spontaneous transformation, and that this alteration does not affect cAMP-dependent protein kinase activity.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1041110108
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  • 4
    Electronic Resource
    Electronic Resource
    Involvement of Na+ and HCO3- in receptor-mediated endocytosis of α2-macroglobulin, epidermal growth factor, and vesicular stomatitis virus (1982)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 113 (1982), S. 353-358 
    Details
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: α2-Macroglobulin (α2M), epidermal growth factor (EGF), and vesicular stomatitis virus (VSV) each enter cultured fibroblasts by receptor-mediated endocytosis. The present study defines some basic ionic requirements in the cell culture medium which are necessary for the maximal rate of endocytosis of these three ligands. Na+ and HCO3- were both necessary for maximal endocytosis of 125I-α2M, 125I-EGF, and 35S-VSV at 37°C. The ion specificities for both the anion and cation requirements were established. The binding of 125I-α2M to its cellular receptors at 4°C was unaffected by the absence of Na+ and HCO3- in the culture medium. In addition, the absence of Na+ and HCO3- in the culture medium did not reduce cellular uptake of horseradish peroxidase by fluid phase endocytosis. Na+ and HCO3- may be general requirements in receptor-mediated endocytosis.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1041130302
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  • 5
    Electronic Resource
    Electronic Resource
    Verapamil enhances the toxicity of conjugates of epidermal growth factor with Pseudomonas exotoxin and antitransferrin receptor with pseudomonas exotoxin (1984)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 120 (1984), S. 271-279 
    Details
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Verapamil, a clinically important calcium channel blocker, has been found to cause a 40-fold enhancement of killing of the human KB cell line by a cytotoxic conjugate of epidermal growth factor with Pseudomonas exotoxin (EGF-PE). Synergistic effects of verapamil and EGF-PE are also seen on HeLa D98 cells and a human epidermal carcinoma cell line, A431. Verapamil also potentiates the effect of a toxic conjugate formed between Pseudomonas exotoxin and a monoclonal antibody to the human transferrin receptor (anti-TFR-PE) and enhances the effect of Pseudomonas exotoxin (PE) alone. Two other calcium antagonists were tested. Diltiazem enhances the cytotoxic effect of EGF-PE, but nifedipine does not. Verapamil does not affect the binding and uptake of 125I-EGF by KB cells, but it significantly delays the disappearance of internalized 125I-EGF from the cells. Density gradient fractionation studies using cell homogenates suggest that 125I-EGF accumulates in an undegraded form in lysosomes when cells are treated with verapamil. By immunofluorescence microscopy using an antibody to PE, EGF-PE was found to accumulate in lysosomes; by electron microscopy the lysosomes had an abnormal appearance. The effects of verapamil on toxicity of EGF-PE and lysosomal function appear to be related. However, it is not known whether the enhanced toxicity of EGF-PE in the presence of verapamil is due to its delayed degradation in lysosomes or some more general effect of verapamil on membrane permeability.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1041200303
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  • 6
    Electronic Resource
    Electronic Resource
    Epidermal growth factor-dependent growth of human KB cells in a defined medium and altered growth factor requirements of KB mutants resistant to EGF-Pseudomonas exotoxin conjugates (1988)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 135 (1988), S. 502-508 
    Details
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: A serum-free culture system was established for human KB carcinoma (HeLa) cells that consisted of a chemically defined medium and several growth factors including epidermal growth factor (EGF), insulin, transferrin, hydrocortisone, and ethanolamine. EGF and insulin showed the greatest effects on the growth rate of KB cells. Insulin-like growth factor l (IGF-l) at the same concentration as insulin stimulated cell growth less than insulin. Transferrin, hydrocortisone, or ethanolamine had no growth-stimulatory effects alone but were stimulatory when combined with EGF and/or insulin. Transforming growth factor-beta inhibited growth and triiodothyronine stimulated growth. The growth factor requirements were established for several KB mutants with low EGF receptor levels that had been selected for resistance to a conjugate of EGF with Pseudomonas exotoxin (EGF-PE). Three of five KB mutants did not respond to EGF; two other mutants responded to a lesser extent than the parental KB cells. Four mutants had a reduced response to insulin and responded to T3; one mutant (ET-30) responded to neither. These results indicate that KB cells selected for EGF-PE resistance have lost their growth response to EGF and illustrate the usefulness of serum-free medium for studying the growth factor requirements of mutants with altered receptor levels.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1041350319
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  • 7
    Electronic Resource
    Electronic Resource
    Genetic characterization of human KB cell lines resistant to epidermal growth factor: Pseudomonas exotoxin conjugates (1988)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 135 (1988), S. 527-532 
    Details
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Pleiotropic human KB cell mutants, selected for resistance to a conjugate of epidermal growth factor with Pseudomonas exotoxin (PE-EGF), were characterized genetically. These mutants have a pleiotropic phenotype, which includes reduced number of EGF receptors and reduced growth rate. Hybrid cells between HeLa D98 and four out of five of these resistant cell lines were more resistant to PE-EGF than hybrids formed between HeLa D98 and parental KB cells. This result indicates that the phenotype of PE-EGF resistance is incompletely dominant in four out of five cases and recessive in one out of five variants. In three separate experiments, transfection of DNA from two of the dominant resistant cell lines resulted in transformation of wild-type KB cells to PE-EGF resistance, confirming the dominant nature of these mutations, which affect levels of EGF receptor in KB cells.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1041350323
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  • 8
    Electronic Resource
    Electronic Resource
    The relationship between cell surface protein and glucose and α-aminoisobutyrate transport in transformed chick and mouse cells (1976)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 89 (1976), S. 827-829 
    Details
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1040890450
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  • 9
    Electronic Resource
    Electronic Resource
    Regulation of intracellular calcium in chick embryo fibroblast: Calcium uptake by the microsomal fraction (1977)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 91 (1977), S. 289-296 
    Details
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The total membrane fraction of a chick embryo fibroblast (CEF) homogenate accumulates calcium in an energy-dependent manner. This activity can be dissociated into azide-sensitive and azide-insensitive components. The azide-sensitive component of calcium uptake is believed to represent mitochondrial calcium uptake. The azide-insensitive component of calcium uptake is enhanced by the presence of a calcium trapping agent such as oxalate, and cannot utilize, ADP, inorganic phosphate and a Krebs cycle substrate to support uptake. The distribution of the azide-insensitive calcium uptake in subcellular fractions suggests that this uptake occurs in other than mitochondrial membranes. The membranes most likely to contribute to the azide-insensitive component of calcium uptake are the endoplasmic reticulum and plasma membrane. A microsomal preparation from CEF cells is essentially devoid of the azide-sensitive calcium uptake activity. This microsomal activity is similar in characteristics to the sarcoplasmic reticulum of skeletal muscle. However the specific activity of CEF microsomal calcium uptake system is much less than that found in the skeletal muscle system. The transport of calcium by these membranes provide a mechanism for the regulation of cytosol calcium levels and may play a role in the control of movement and growth of cultured cells.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1040910213
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  • 10
    Electronic Resource
    Electronic Resource
    EGF induces receptor down-regulation with no receptor recycling in KB cells (1985)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 122 (1985), S. 166-170 
    Details
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Several ligands, including epidermal growth factor (EGF), have been found to negatively modulate or down-regulate their specific plasma membrane receptors. Using both 125I-EGF and a monoclonal antibody against the EGF-receptor (EGF-R1), we studied the down-regulation of the EGF-receptor in the human adenocarcinoma cell line KB. The results presented here demonstrate that incubating KB cells at 37°C with EGF rapidly decreases the number of plasma membrane EGF-receptors. In addition, there is a concomitant rise of equal magnitude in the number of EGF molecules taken up. The latter result argues strongly that there is negligible recycling of the EGF-receptor in KB cells and that the major portion of internalized EGF-receptor complexes are transported to lysosomes and subsequently degraded. The fate of the EGF-receptor is markedly different from that of receptors not subject to down-regulation. The biochemical signals that operate to regulate such diverse receptor traffic in cells remains to be elucidated.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1041220125
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