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  • 1
    Electronic Resource
    Electronic Resource
    Increases in cyclic AMP potentiate competence formation in BALB/c-3T3 cells (1982)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 111 (1982), S. 201-206 
    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 of platelet-derived growth factor and fibroblast growth factor to stimulate the initiation of DNA synthesis in quiescent BALB/c-3T3 cells was enhanced by cholera toxin. However, the addition of cholera toxin to unsupplemented medium was not mitogenic, nor did cholera toxin increase the mitogenic potential of mediuum supplemented with platelet-poor plasma. The enhancement of serum-induced DNA synthesis by cholera toxin was due to a specific effect on competence formation and not plasma-controlled progression. Cholera toxin increased the rate of competence formation during a transient exposure of quiescent cells to platelet-derived growth factor; this rate was further increased by the addition of isobutylmethylxanthine, a cyclic nucleotide phosphodiesterase inhibitor. Intracellular cyclic AMP concentrations in quiescent BALB/c-3T3 cells were increased 2- to 3-fold after the addition of cholera toxin. The addition of cholera toxin plus 30 m̈M isobutylmethylxanthine caused an even greater (7- to 8-fold) increase in the cellular levels of cyclic AMP. That these increases in cyclic AMP concentrations mediated at least part of the increased sensitivity of quiescent cells to competence factors was substantiated by the observation that 0.01 to 1 mM monobutrylcyclic AMP or 8-bromocyclic AMP also caused a concentration-dependent potentiation of competence formation in quiescent cells during a transient exposure to platelet-derived growth factor.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1041110212
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  • 2
    Electronic Resource
    Electronic Resource
    Modulation of the platelet-derived growth factor induced replicative response (1985)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 123 (1985), S. 10-16 
    Details
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Quiescent cultures of density arrested BALB/c-3T3 cells have been sensitized to the growth stimulatory action of the platelet-derived growth factor (PDGF). Sensitization was achieved by depriving the cultures of PDGF prior to growth stimulation and was noted after transfer of cultures from medium supplemented with 10% serum to medium containing either an equivalent concentration of platelet-poor plasma or a low concentration (0.5%) of serum. Sensitized cultures required less pure PDGF for growth stimulation than non-sensitized ones. In addition such cultures required less mitogen to synthesize a PDGF modulated major excreted protein (MEP). The mechanism of sensitization was investigated. Sensitized cultures did not bind more PDGF than non-sensitized ones. Rather, sensitization appeared to result from the loss of cells that occurred when cultures were deprived of PDGF. Such a loss increased the amount of PDGF available per cell, causing a higher percentage of cells to enter the S phase. Similarly, the amount of PDGF per cell regulated MEP synthesis. Furthermore, in non-sensitized cultures (containing the same number of cells), the absolute quantity rather than the concentration of PDGF regulated DNA synthesis. It appears that the amount of PDGF per cell modulates mitogenesis.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1041230103
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  • 3
    Electronic Resource
    Electronic Resource
    Control of the Balb/c-3T3 cell cycle by nutrients and serum factors: Analysis using platelet-derived growth factor and platelet-poor plasma (1979)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 99 (1979), S. 395-405 
    Details
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Much controversy regarding the relationship between nutrients and serum in regulation of cell growth can be reconciled by recognizing that serum contains multiple factors which regulate different events in the cell cycle. Serum was fractioned into a platelet-derived growth factor (PDGF), which induces cells to become competent to synthesize DNA, and plasma which allows competent cells to traverse G0/G1 and enter the S phase. Nutrients are not required for the cellular response to PDGF; however amino acids are required for plasma to promote the entry of PDGF-treated, competent cells into S phase. The nutrient independent, PDGF-modulated, growth regulatory event (competence) is located 12 hours prior to the G1/S phase boundary in quiescent, density-arrested Balb/c-3T3 cells. The nutrient dependent, plasma-modulated event is located six hours prior to the G1/S phase boundary and corresponds in time to a plasma dependent growth arrest point. Moreover, plasma controls the concentration of amino acids required for DNA synthesis. Infection of density-arrested Balb/c-3T3 cells with SV40 overrides both the nutrient independent and the nutrient dependent growth regulatory events.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1040990314
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  • 4
    Electronic Resource
    Electronic Resource
    Inhibition of BALB/c-3T3 cells in late G1: Commitment to DNA synthesis controlled by somatomedin C (1981)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 107 (1981), S. 31-39 
    Details
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Methylglyoxal bis-(guanylhydrazone) (mGBG) blocked the stimulation of DNA synthesis in quiescent, density-inhibited BALB/c-3T3 cells treated with platelet-derived growth factor (PDGF) and platelet-poor plasma (PPP). Competence formation produced by a transient exposure to PDGF was not effected by mGBG. In contrast, mGBG effectively inhibited the PPP-stimulated progression of competent cells through the G1 phase of the cell cycle, although maximal inhibition was observed when mGBG was present during both the exposure to PDGF- and PPP-supplemented media. When quiescent cells were treated with PDGF and PPP-supplemented media in the presence of mGBG for 12-18 hours and the mGBG was then removed, cells entered the S phase after a 4 hour lag. The rate of entry into the S phase, but not the time necessary for the cells to progress from the mGBG block into the S phase, was dependent on the concentration of PPP present after removal of the mGBG. Either somatomedin C or insulin, but not epidermal growth factor, fibroblast growth factor, or PDGF were able to substitute for PPP in allowing cells to enter the S phase after the cells were released from the mGBG block. A marked inhibition of (3H)-leucine incorporation in serum-stimulated cultures was produced at mGBG concentrations which caused no decrease in the amount of (3H)-uridine incorporated during a short (15 minute) pulse. The ability of hormones to allow cells to progress to the late G1 phase and become committed to DNA synthesis after a mGBG inhibition was not related to their ability to restore the normal rate of protein synthesis as determined by (3H)-leucine incorporation.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1041070105
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  • 5
    Electronic Resource
    Electronic Resource
    Mitogenic activity elaborated by macrophage-like cell lines acts as competence factor(s) for BALB/c 3T3 cells (1982)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 110 (1982), S. 93-100 
    Details
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The culture medium from several murine macrophage-like cell lines contained a mitogenic activity that functioned synergistically with platelet-poor plasma to induce DNA synthesis in quiescent density-inhibited BALB/c 3T3 fibroblasts. This mitogenic activity was generated by P388D1 (and other established lines of) macrophage-like cells that were cultured either in medium alone or in medium supplemented with platelet-poor plasma. The amount of mitogenic activity produced was directly related to the length of time the macrophage-like cells were maintained in the medium. Serum-free medium conditioned by macrophage-cells did not stimulate DNA synthesis in density-inhibited 3T3 cells in the absence of plasma; however, a transient (4-hr) exposure to serum-free macrophage-conditioned medium allowed quiescent cells to respond to plasma-derived progression factors. The addition of plasma to 3T3 cells that had been treated with the macrophage-conditioned medium brought about DNA synthesis after a 12-hr lag. The mitogenic activity that was in macrophage-conditioned medium bound to DEAE-Sephadex and eluted in a single peak using a linear NaCl gradient. This macrophage-derived competence factor was not mitogenic for lymphocytes and was clearly separated by DEAE-Sephadex chromatography from the major peak of the previously described mitogenic monokine, Interleukin-I (lymphocyte activating factor).
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1041100115
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  • 6
    Electronic Resource
    Electronic Resource
    Differential sensitivity of fibroblasts to epidermal growth factor is related to cyclic AMP concentration (1984)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 118 (1984), S. 291-297 
    Details
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The differential sensitivity of various cell lines to the mitogenic effects of epidermal growth factor (EGF) was investigated. Two lines of evidence suggest that cellular capacity to respond proliferatively to EGF is related to intracellular cyclic AMP concentration. First, the ability of three density-arrested cell lines to synthesize DNA in response to EGF was directly proportional to the basal cyclic AMP level of the cells at quiescence. Second, treatment of cultures with various agents known to promote intracellular cyclic AMP accumulation increased the sensitivity of all three cell lines to EGF. The mechanism whereby cyclic AMP modulates EGF responsiveness is not known; cholera toxin did not affect the cellular capacity to bind or internalize and process EGF. Although platelet-derived growth factor (PDGF) had no effect on cyclic AMP levels, transient treatment of quiescent cultures with this polypeptide also enhanced EGF sensitivity. In agreement with previous data and in contrast to cholera toxin, PDGF induced the down-regulation of EGF receptors in the three cell lines. These data suggest that the capacity of various cell types to respond to EGF is subject to both intracellular regulation by cyclic AMP and extracellular modulation by factors such as PDGF which can affect EGF receptor activity.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1041180312
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  • 7
    Electronic Resource
    Electronic Resource
    Regulation of cyclic nucleotide phosphodiesterase forms by serum and insulin in cultured fibroblasts (1979)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 100 (1979), S. 497-507 
    Details
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: A rapid reduction of cyclic nucleotide phosphodiesterase activity occurs after the replating of confluent cultures of BHK 21 c/13 fibroblasts into fresh medium. This reduction in activity depends on the density to which the cultures are reseeded and the concentration of serum in the medium. Enzyme activity in BHK cells is restored after 24 to 48 hours if cells are diluted into medium containing 10% fetal calf serum or 0.5% fetal calf serum supplemented with insulin (10-6 M), but not into 0.5% serum alone. The restoration in enzyme activity is blocked by cycloheximide or Actinomycin D.When BHK cells become quiescent by maintenance in 0.5% serum conditions for 48 hours, a rapid (15-60 minutes) increase in cyclic AMP phosphodiesterase activity occurs when 10% serum is added to the cultures. Enzyme activity is increased even further after 24 to 48 hours in the 10% serum. Cycloheximide or Actinomycin D do not affect the rapid increase in enzyme activity in response to serum, but completely inhibit the long term increase. In contrast to serum, insulin (10-8 to 10-6 M) has no short term effect, but does increase enzyme activity after 24 to 48 hours to levels comparable to those seen with addition of 10% serum. As is the case with serum, this long term effect of insulin on enzyme activity is prevented by inhibitors of protein and RNA synthesis.Kinetic analyses of cyclic AMP phosphodiesterase activity in homogenates of quiescent BHK cells indicate the presence of only high Km (≃ 20 μM) enzyme activity. Addition of serum or insulin to quiescent cells results in the appearance of apparent low Km enzyme activity in homogenates. Sucrose gradient analysis of BHK cells displays two forms of cyclic AMP phosphodiesterase enzyme activity: a 3-4 S form and 5-6 S form. In quiescent cells, the 5-6 form greatly predominates relative to the 3-4 form. Addition of serum to quiescent cells results in a rapid appearance of increased 3-4 S form enzyme activity. Insulin also increases the activity of this higher affinity 3-4 S enzyme form after 24 to 48 hours in culture. The functional significance of short and long term regulation of cyclic nucleotide phosphodiesterase(s) in cells is discussed.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1041000312
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  • 8
    Electronic Resource
    Electronic Resource
    Effect of ouabain on growth regulation by serum components in Balb/C-3T3 cells: Inhibition of entry into s phase by decreased protein synthesis (1980)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 105 (1980), S. 439-448 
    Details
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The effect of inhibition of the cell membrane Na+-K+ pump on the Balb/c-3T3 cell growth cycle was studied. Inhibition of the Na+-K+ pump resulted in a dose-dependent reduction of intracellular K+ concentration ({K+}i). However, inhibition of protein synthesis in G0/G1 and of subsequent entry into S phase occurred only after {K+}i fell below a critical threshold (50-60 mmoles/liter). Thus, when the {K+}i falls below a critical threshold, protein synthesis is inhibited, preventing cells from entering the S phase.The platelet-derived growth factor (PDGF) induces cells to become “competent” to traverse the cell cycle; the platelet-poor plasma component of serum allows competent cells to progress through G0/G1 and enter S phase. Inhibition of the Na+-K+ pump did not prevent the induction of competence by PDGF, but it did reversibly inhibit plasma-mediated events in early G0/G1. Similarly, cycloheximide inhibited plasma-mediated events but did not prevent PDGF-induced competence. Thus, protein synthesis may not be required for induction of competence; alternatively, the induction of the competent state may occur in these cells after removal of PDGF and protein synthesis inhibitor. Protein synthesis is required for subsequent plasma-mediated events in G0/G1.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1041050308
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  • 9
    Electronic Resource
    Electronic Resource
    Identification of the cellular mechanisms responsible for platelet-derived growth factor induced alterations in cytoplasmic vinculin distribution (1986)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 126 (1986), S. 115-125 
    Details
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Exposure of quiescent density arrested BALB/c-3T3 cells (clone A31) to platelet-derived growth factor (PDGF;6-12 ng/ml) results in a rapid, reversible, time-and dose-dependent removal of vinculin from adhesion plaques (Herman and Pledger, 1985). Potential cellular mechanisms involved in PDGF-induced removal of vinculin from adhesion plaques were examined. Removal of vinculin from adhesion plaques following exposure of cells to PDGF was temperature dependent, occurred in many fibroblast cell lines, and could be mimicked by 12-tetradecanoyl phorbol-13-acetate (TPA; 5-125 nM) or melittin (0.35 μM). Unlike the effect of PDGF, TPA-or melittin-induced vinculin disruption was not reversible. The removal of vinculin from adhesion plaques was inhibited by trifluoroperazine (TFP; 2.5 μM). 8-(N,N-diethylamino) octyl-3,4,5-trimethoxy benzoate (TMB-8; 1.0 μM), mepacrine (220 μM), n-α-p-tosyl-L-lysine chloromethylketone (TLCK; 100 μM), phenylmethoxysulphonylfluoride (PMSF; 500 μM), and e-aminocaproic acid (e-ACA; 100 μM); however, amiloride (100 μM), A23187 (20 μM), and chloroquine (1 mM) were unable to inhibit this effect. Melittin disruption of vinculin was inhibited by (in order of decreasing effectiveness) mepacrine 〉 TMB-8 〉 TFP 〉 leupeptin 〉 PMSF, whereas A23187 and amiloride had no effect. The return of vinculin to adhesion plaques following PDGF treatment required de novo mRNA transcription and protein synthesis and was associated with PDGF-stimulated synthesis of vinculin.The observation that both PDGF- and melittin-induced removal of vinculin from adhesion plaques is inhibited by mepacrine suggests that phospholipase activation may be an early and important step in PDGF-induced disruption of vinculin from adhesion plaques. In addition, TFP, TMB-8 and protease inhibitor inhibition of both the PDGF and melittin effects on vinculin distribution, coupled with the finding that TPA can mimic the PDGF or melittin response, suggests that Ca2+, calmodulin, protein kinase C, and /or proteolysis may play an important role(s) in the removal of vinculin from adhesion plaques following PDGF addition. The lack of effect of A23187 addition on vinculin distribution suggests that alterations in cellular Ca2+ is necessary but not sufficient for vinculin removal from adhesion plaques.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1041260116
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  • 10
    Electronic Resource
    Electronic Resource
    Transforming viruses directly reduce the cellular growth requirement for a platelet derived growth factor (1978)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 97 (1978), S. 371-380 
    Details
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Early passage mouse embryo fibroblasts, mouse 3T3 cell lines, and early passage diploid human fibroblasts grew to higher cell densities in tissue culture medium supplemented with serum than in medium supplemented with defibrinogenated platelet-poor plasma (PPP). Unlike the mouse cells, the human fibroblasts displayed this differential growth response only in the presence of hypophysiologic concentrations of calcium. The addition of heat-treated extracts of human platelets to PPP-supplemented medium stimulated the replication of both the normal mouse cells and early passage human embryo fibroblasts.Human or mouse fibroblasts transformed by either retroviruses or by SV40, including SV40 infected “serum revertants” and “flat transformants,” grew to equal cell densities in medium supplemented with either serum or PPP. Infection of Balb/c-3T3 cells with SV40 rapidly induced them to grow in PPP-supplemented medium demonstrating that the ability of SV40-transformed cell lines to proliferate in PPP-supplemented medium does not arise from the cell culture selection procedures usually employed to obtain stable virus-transformed cell lines. 3T3 cells infected but not transformed by retroviruses do not replicate in PPP-supplemented medium demonstrating that reduction of the growth requirement for the platelet growth factor(s) by retroviruses is a transformation-specific response. Cell cultures that did not proliferate well in PPP-supplemented medium did not form tumors when inoculated into athymic nude mice. Many, although not all, of the lines which grew well in PPP medium were tumorigenic in nude mice. Together, these findings indicate that: (1) normal fibroblast-like cells display a growth requirement for factor(s) present in serum but not found in PPP; (2) this serum specific growth factor is derived from platelets; (3) a primary response to viral transforming genes is a reduction in the growth requirement for these platelet-derived factors; and (4) cells that have a reduced requirement for the platelet-derived growth factor are often tumorigenic.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1040970312
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