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  • 11
    Electronic Resource
    Electronic Resource
    Tyrosine phosphorylation in cells treated with transforming growth factor-β (1986)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 129 (1986), S. 159-166 
    Details
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Cells stimulated with epidermal growth factor (EGF) or any one of a diverse group of other mitogenic agents display an increased tyrosine phosphorylation of a pair of 42,000 Mr proteins. Transforming Growth Factor-β (TGF-β) is able to potentiate the mitogenic effects of Epidermal Growth Factor on some fibroblastic cells (such as the NRK-49F cell line) and, in addition, permits the anchorage-independent growth of these cells. In this study we asked whether these growth-regulatory actions of Transforming Growth Factor-β are associated with changes in tyrosine phosphorylation of cellular proteins, in particular the 42,000 Mr proteins. We found no effect of Transforming Growth Factor-β on the extent or time-course of tyrosine phosphorylation, either by itself or in combination with Epidermal Growth Factor. Since the tyrosine phosphorylation of the 42,000 Mr proteins is stimulated both by receptors with tyrosine kinase activity and by diacylglycerol analogs (but not by Transforming Growth Factor-β), we suggest that the activity of the receptor for Transforming Growth Factor-β is linked neither to tyrosine phosphorylation nor to phosphatidyl inositol turnover.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1041290206
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  • 12
    Electronic Resource
    Electronic Resource
    Normalization of epidermal growth factor receptor and transforming growth factor production in drug resistant variants derived from adenovirus transformed cells (1988)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 134 (1988), S. 467-472 
    Details
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Variants (G2, G5) resistant to the cancer chemotherapeutic drug methylglyoxal bis (guanylhydrazone) (MGBG) were isolated from adenovirus type 2 transformed rat brain cells (F4; Sircar et al., 1987). Although at least one of these variants continued to express the adenovirus Ela and Elb transforming proteins, they both exhibited a detransformed phenotype as witnessed by flat morphology, loss of anchorage independent growth, and tumor forming capacity. Reverse transformation suggested the possibility of changes in growth factor receptors and the production of transforming growth factors. To test this possibility, we investigated the status of epidermal growth factor receptors (EGF-r) and transforming growth factor alpha (TGF-α) production in F4, G2 and G5 cells. The level of 125I-labeled EGF binding to intact drug resistant cells increased by 2- to 3-fold compared to the transformed parental cell. Scatchard analysis suggests that increased binding was the result of increased receptor levels rather than altered affinity of receptor for ligand. The production of growth factors which compete with 125I-labeled EGF binding declined in the detransformed G2 and G5 cells to a level intermediate between transformed (F4) and normal cells (FR3T3). EGF-receptor increase and the complementary decrease in growth factor production in the drug resistant variants may be associated with detransformation.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1041340319
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  • 13
    Electronic Resource
    Electronic Resource
    Mitogen-stimulated tyrosine phosphorylation of a 42-kD cellular protein: Evidence for a protein kinase-C requirement (1988)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 135 (1988), S. 285-292 
    Details
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Tyrosine phosphorylation of a 42-kD, cytosolic protein is a rapid consequence when quiescent cells are stimulated with any one of a diverse group of mitogenic agents. Among the inducers of this tyrosine phosphorylation are activators of protein kinase C, raising the possibility that this serine/threonine-specific protein kinase plays a role in mitogen-induced tyrosine phosphorylation. Using fibroblastic cells depleted of protein kinase C by chronic treatment with the tumor promoter tetradecanoyl phorbol acetate (TPA), we now show that protein kinase C is required for the tyrosine phosphorylation of the 42-kD protein, even when epidermal growth factor (EGF), whose receptor is a tyrosine-specific protein kinase, provides the initial stimulus. EGF is able to induce other cellular phosphorylations independent of protein kinase C, whereas thrombin appears to require the protein kinase C-dependent pathway. These findings suggest that phosphorylation of the 42-kD protein is part of a protein kinase C-dependent kinase cascade involved in intracellular signalling.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1041350216
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  • 14
    Electronic Resource
    Electronic Resource
    Effect of heat shock on RNA metabolism in HeLa cells (1988)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 135 (1988), S. 377-386 
    Details
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Incubation of HeLa cells at 42°C results in pronounced inhibition of the accumulation of 18S and 28S ribosomal RNA (rRNA) and non-heat shock polyadenylated messenger RNA (mRNA) in the cytoplasm. Accumulation of transfer RNA and 5S ribosomal RNA is not affected. Transcription of rRNA precursor is reduced to approximately 50% of the 37°C rate after 10 min of hyperthermia and declines to 30 of the control rate after 1 hr. In contrast, the accumulation of mature rRNA in the cytoplasm is inhibited more than 95%. Quantitative hybridization experiments and Northern blot analysis detect little accumulation of rRNA precursor sequences in nuclei, suggesting that the majority of the rRNA that is synthesized is degraded. Heat stress at 42°C was found to have little effect on transcription of most non-heat shock mRNAs. However, accumulation of individual non-heat shock mRNAs in the cytoplasm proceeds at reduced rates. These results indicate that the primary effect of elevated temperature on RNA metabolism in mammalian cells is inhibition of processing and/or transport. Despite this, steady-state levels of abundant and rapidly turning over mRNA species remain unchanged during prolonged heat stress. We find that the half-life of c-myc mRNA increases greater than twofold at 42°C. Thus, 42°C heat stress appears to inhibit both accumulation and turnover of non-heat shock mRNA.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1041350304
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  • 15
    Electronic Resource
    Electronic Resource
    Coordinate regulation of gluconeogenesis by the glucocorticoids and glucagon: Evidence for acute and chronic regulation by glucagon (1981)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 109 (1981), S. 83-90 
    Details
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The coordinate regulation of gluconeogenesis by the glucocorticoids and glucagon in primary cultures of adult rat liver parenchymal cells has been studied. The results suggest that glucagon stimulation of glucose production from 3-carbon precursors is composed of at least two components which the glucocorticoids differentially affect. Glucagon treatment of hepatocytes results in an immediate increase in glucose production which is not blocked by cycloheximide and occurs in the absence of any detectable increase of phosphoenolpyruvate carboxykinase activity. This component appears to be regulated by a post-translational mechanism and involves redirection of carbon flow from glycolysis to gluconeogenesis. The second component is characterized by the need for long-term glucagon treatment. This increase in glucose production can be blocked by cycloheximide and is correlated with an increase in phosphoenolpyruvate carbooxykinase activity. The reaction that is accelerated by long-term glucagon incubation is located prior to the triose-phosphate level since long-term incubation with glucagon fails to increase glucose production from dihydroxyacetone any more than does short-term incubation. It is suggested that phosphoenolpyruvate carboxykinase rather than amino acid transport is the key pacemaker reaction in the long-term incubation since the direction and magnitude of the response for glucocorticoid and glucagon stimulation of glucose production is the same whether alanine or lactate is used as the 3-carbon precursor. The glucocorticoids exhibit an additive effect on glucagon-stimulated glucose production for the first component whereas they amplify the second component.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1041090110
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  • 16
    Electronic Resource
    Electronic Resource
    Down-modulation of EGF receptors in cells transformed by the src oncogene (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 131 (1987), S. 450-457 
    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 src oncogene expression on epidermal growth factor (EGF) receptors have been investigated in mouse 3T3 and rat-1 fibroblasts. Transformation of both cell types with src resulted in marked reductions in cellular EGF receptor levels, as assayed by either 125I-EGF binding or immunoprecipitation of receptor protein from radiolabeled cell lysates. In contrast to cells transformed by other types of retroviral oncogenes, the loss of EGF receptors in the src-transformed cells did not appear to be due to secreted transforming growth factor-α (TGF-α), since such factors were undetectable in culture fluids from the src-transformed cells. By several criteria of transformation, an EGF-receptorless cell line infected with src was shown to be transformed, suggesting that EGF receptors themselves are not obligatory to the src transformation process. We suggest that pp60src down-modulates EGF receptors by an intracellular mechanism and that the loss of the receptors is symptomatic of more general effects of pp60src on the machinery of growth regulation.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1041310318
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  • 17
    Electronic Resource
    Electronic Resource
    The in vitro response of thymic lymphocytes of the pig to phytohemagglutininThis work was aided by Pennsylvania Plan Funds, grant FR-00120-01 from the Division of Research Facilities and Resources, and by U.S.P.H.S. grant 5T1 Ca-5097.The work was performed at the interdisciplinary cancer research facilities of the school of veterinary medicine. (1966)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 67 (1966), S. 285-299 
    Details
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The response of thymic lymphocytes of the pig to phytohemagglutinin was studied with H3 thymidine in cultures, from 0-72 hours. At the beginning of the culture period 6-18% of lymphocytes were in DNA synthesis. during the first 24 hours a sharp decrease in the number of DNA synthesizing cells was observed in both pha and control cultures, although pha cultures consistently showed small but significantly greater numbers of DNA synthesizing cells. this was followed by a definite peak in DNA synthesis and mitotic response of a minority of the cells in pha cultures between 48-54 hours, whereas in control cultures activity ceased. in addition, a small proportion of the progeny of initially DNA synthesizing medium sized lymphocytes was apparently stimulated by pha and found in mitosis by 48 hours.It was concluded that the thymus contains a fraction of lymphocytes, not in the mitotic cycle, which are capable of being transformed by pha to mitotic activity. the data also suggests some stimulation of cells already in the mitotic cycle.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1040670209
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  • 18
    Electronic Resource
    Electronic Resource
    Difference between medullary and cortical thymic lymphocytes of the pig in their response to phytohemagglutininThis work was aided by Pennsylvania Plan Funds and U.S.P.H.S. grants FR-00120-02 and 5 TI Ca 5097.Most of this work was performed at the Interdisciplinary Cancer Research Facilities of the School of Veterinary Medicine. (1966)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 68 (1966), S. 117-125 
    Details
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Pig thymus tissue was cultured with organ culture techniques in the presence and absence of phytohemagglutinin in the culture medium. Morphologic and autoradiographic observations indicate that in the pig, lymphocytes capable of responding to phytohemagglutinin are located predominantly in the medulla of the thymus.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1040680206
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  • 19
    Electronic Resource
    Electronic Resource
    Serum stimulation of potassium fluxes, ouabain binding, and sodium fluxes in quiescent chicken embryo fibroblasts (1980)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 103 (1980), S. 363-370 
    Details
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Growth-contingent alterations in potassium and sodium fluxes, ouabain binding, and potassium ion content were examined following serum stimulation of quiescent, density-inhibited chicken embryo fibroblasts. Serum stimulation resulted in very rapid 1.5- to 1.8-fold increases in ouabain-sensitive potassium influx and lesser 1.4- to 1.5-fold increases in potassium efflux and sodium influx. Potassium influx stimulation was maximal after addition of 5-20% calf serum and was unaffected by cycloheximide inhibition of protein synthesis. Reflecting the slightly greater stimulation of potassium influx versus potassium efflux, potassium ion levels were 10-15% higher in serum-stimulated compared to unstimulated cells. Specific ouabain binding levels in stimulated and unstimulated control cells were initially similar, however, by four hours after stimulation a 40-50% increase in specific ouabain binding was observed. Incubation with ouabain was found also to inhibit later serum-stimulated hexose uptake and thymidine incorporation; this blockage may be a consequence of subnormal potassium levels rather than ouabain inhibition of the serum-stimulated potassium influx.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1041030222
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  • 20
    Electronic Resource
    Electronic Resource
    Uridine transport and RNA synthesis in growing and in density-inhibited animal cells (1971)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 77 (1971), S. 157-167 
    Details
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Both chick embryo fibroblasts and mouse 3T3 cells reduce the rate at which they incorporate H3 uridine into RNA as their growth becomes inhibited at high cell density. This reduction occurs as a function of the cell population density, and with chick embryo cells (in contrast to 3T3 cells) it is not accompanied by significant medium alterations. This indicates the importance of the cell population density in the control of cellular metabolism.The decline in H3 uridine incorporation is paralleled by a decline in the rate of uptake of the isotope into the acid-soluble pool, suggesting that decreased entry of H3 uridine into the cell, rather than a decreased rate of RNA synthesis, is responsible for the reduced rate of incorporation into RNA of density-inhibited cells. This suggestion was confirmed by finding that when the restriction on uridine uptake was overcome by increasing the concentration of uridine in the medium, the density-dependent inhibition of uridine incorporation was largely reversed. We conclude that, even though the rate of H3 uridine incorporation into RNA is reduced three- to five-fold in density-inhibited cells, the rate of synthesis of pulse-labeled RNA continues at 70 to 85% of the rapidly-growing rate.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1040770205
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