Desensitization of enucleated cells to hormones and role of cytoskeleton in control of normal hormonal response.

Simantov, Rabi; Shkolnik, Tamar; Sachs, Leo

doi:10.1073/pnas.77.8.4798

Cited by 27 publications

(7 citation statements)

References 33 publications

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“…Changes in cell shape have also been associated with the regulation of DNA synthesis, cell growth (Folkman and Moscona, 1978) and overall protein synthesis (BenZe'ev et d., 1980) in fibroblasts and the growth of adrenal and granulosa cells (Gospodarowicz et al, 1980). The present results indicate that changes in cell shape can regulate specific proteins, possibly due to changes in response to hormones and nutrients associated with changes in the cytoskeleton (Folkman and Moscona, 1978;Simantov et al, 1980). Further identification of these proteins may help in clarifying the mechanism of this association between the expression of specific proteins and cell shape.…”

Section: Discussionmentioning

confidence: 57%

Regulation of gene expression by tumor promoters. II. Control of cell shape and developmental programs for macrophages and granulocytes in human myeloid leukemic cells

Liebermann

Hoffman-Liebermann

Sachs

1981

Intl Journal of Cancer

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Regulation of the developmental programs for macrophages and granulocytes has been analysed, using two-dimensional gel electrophoresis of the cytoplasmic protein changes, in a human myeloid leukemic cell line (HL60) that can be induced to differentiate to macrophages by the macrophage and granulocyte-inducing (MGI) protein and the tumor promoter 12-0-tetradecanoyl-phorbol-13-acetate (TPA), and to granulocytes by dimethylsulfoxide (DMSO). Studies on the protein changes induced by the different inducers showed a similar developmental program for macrophage differentiation induced by MGI or TPA, which differed from the beginning from the granulocyte program induced by DMSO. Comparison with normal cells from human peripheral blood has shown that the develop mental programs induced in the HL60 cells are relevant to the normal programs of differentiation for these two cell types. Unlike MGI and DMSO, TPA induces rapid attachment of the HL60 cells t o the surface of the Petri dish. Combined treatment with TPA and DMSO showed cell attachment, extensive spreading of the cells, the regulation of specific proteins and expression of the macrophage program. The addition of TPA t o cells induced for the granulocyte program by DMSO resulted in cell attachment and spreading and a switchover from the granulocyte t o the macrophage program. The results indicate that cells in suspension can express either the macrophage or granulocyte program depending on the inducer, and that changes in cell shape associated with cell attachment induced by TPA can regulate specific proteins and restrict the developmental program to macrophages. It is suggested that the in vivo environment of cells in relation t o the possibilities for cell adhesion, which can be regulated by tumor promotors, may play a major role in determining the developmental program of myeloid and other cell types.Normal myeloblasts exposed to the appropriate macrophage and granulocyte-inducing (MGI) protein, can be induced to differentiate to macrophages or granulocytes (Ginsburg and Sachs, 1963; Sachs, 1965, 1966;Ichikawa et al., 1966;Sachs, 1974Sachs, , 1978Sachs, , 1980 Lotem etal., 1980). The ability to differentiate to these two cell types has also been found in clones of myeloid leukemic cells (Paran et al., 1970;Sachs, 1974Sachs, , 1978Sachs, , 1980Lotem et al., 1980) and can be regulated in appropriate clones by different inducers (Lotem and Sachs, 1974;Sachs, 1978;Falk and Sachs, 1980). Thus, cells of the human myeloid leukemic cell line HL60 (Collins et al., 1977(Collins et al., , 1978 can be induced to differentiate to macrophages by MGI (Lotem and Sachs, 1979) and tumor-promoting phorbol esters including 12-0-tetradecanoylphorbol-13-acetate (TPA) (Lotem and Sachs, 1979;Rovera et al., 1979) that act via MGI (Lotem and Sachs, 1979), and to granulocytes by dimethylsulfoxide (DMSO) (Collins et al., 1978).The two different cell types have been identified by their cell morphology (Collins et al., 1978;Lotem and Sachs, 1979), some enzymes (Rovera et al., Vorbrodt et a...

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Section: Discussionmentioning

confidence: 57%

Regulation of gene expression by tumor promoters. II. Control of cell shape and developmental programs for macrophages and granulocytes in human myeloid leukemic cells

Liebermann

Hoffman-Liebermann

Sachs

1981

Intl Journal of Cancer

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“…This correlates with the observation that microtubules had apparently not reassembled within 2 hr after the removal of colchicine (not shown (21,22) and mitogenic stimulation (12)(13)(14)(15) (Fig. 3) …”

Section: Methodsmentioning

confidence: 64%

Microtubule-disrupting agents affect two different events regulating the initiation of DNA synthesis in Swiss 3T3 cells.

Otto¹,

Ulrich²,

Zumbe³

et al. 1981

Proc. Natl. Acad. Sci. U.S.A.

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Normal animal cells, in vivo as well as in vitro, are able to regulate the replication of chromosomal DNA and cell division in response to changes in their extracellular environment (1-3). Cultured mouse cells have provided a useful model system for study of the mechanisms that control the rate of proliferation. Such cells become quiescent when they are confluent or when the culture medium is depleted of growth factors (1). In Swiss mouse 3T3 cells the addition ofgrowth factors such as epidermal growth factor (EGF) (4, 5), fibroblast growth factor (6, 7), or prostaglandin F2a (8) will stimulate the initiation of DNA synthesis. Kinetic studies indicate that these growth factors regulate two processes: they set in motion a constant, time-dependent sequence of events comprising the prereplicative period (lag phase), and they regulate the rate at which the cells initiate DNA synthesis (3). The latter process appears to follow firstorder kinetics and can be quantified by an apparent rate constant k (9, 10). The value of k given by a growth factor can be modulated by a number of nonmitogenic compounds, among them nutrients, ions, and hormones such as insulin and hydrocortisone (3,5,7,8). The length of the lag phase is about 15 hr and is independent of the final value of k (3, 8).Of central importance in the understanding of growth regulation in animal cells is the elucidation of those events participating in the transmission of the mitogenic signals to the intracellular targets ultimately involved in the initiation of DNA synthesis. A number of observations have associated components of the cytoskeleton with regulatory events in growth stimulation (11). In normal fibroblastic cells the initiation of DNA synthesis stimulated by growth factors can be enhanced by microtubule-disrupting drugs (12-15). Also, the expression of the src gene alters the microtubular organization, which correlates with an increased rate of proliferation (16,17).From results presented here we conclude that the intact cytoskeleton may exert a restrictive control on some event(s) regulating the initiation of DNA synthesis. Colcemid and colchicine have a synergistic effect on the rate constant stimulated by EGF alone or plus insulin, but only when added earlier than 8 hr of the lag phase. Removal of Colcemid before 10 hr results in a loss ofthe synergy, which correlates with a rapid reassembly of the microtubules. Furthermore, disruption of microtubules for 8 hr prior to the addition of EGF shortens the lag phase, irrespective of the synergistic effect. This indicates that the organization of the microtubules is affecting at least two different events involved in the initiation of DNA synthesis independently of each other. MATERIALS AND METHODSCell Cultures. Swiss mouse 3T3 cells (18) were propagated at 37°C in a 10% C02/90% air atmosphere in Dulbecco-Vogt's modified Eagle's medium containing streptomycin (100 ,.ug/ ml), penicillin (100 units/ml), and 10% fetal calf serum (8).Measurement of the Initiation of DNA Synthesis and Determination of Rate ...

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“…One common biochemical characteristic of all IFs is phosphorylation of their subunit proteins (14). Protein phosphorylation and dephosphorylation are known to be important regulatory events in many cellular metabolic processes (13), and it is possible that similar mechanisms may be involved in the regulation of cellular architecture (22). vimentin in chicken embryonic skeletal myotubes is stimulated by 3-adrenergic hormones or by 8-bromo-cAMP (BrcAMP), resulting in increased phosphorylation of specific desmin tryptic peptides.…”

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confidence: 99%

Cyclic AMP-modulated phosphorylation of intermediate filament proteins in cultured avian myogenic cells.

Gard¹,

Lazarides²

1982

Mol. Cell. Biol.

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The intermediate filament proteins desmin and vimentin and the muscle tropomyosins were the major protein phosphate acceptors in 8-day-old myotubes incubated for 4 h in medium containing radiolabeled phosphate. The addition of isoproterenol or 8-bromo-cyclic AMP (BrcAMP) resulted in a two-to threefold increase in incorporation of 32 o4 into both desmin and vimentin, whereas no changes in the incorporation of 32p04 into tropomyosin or other cellular proteins were observed. The BrcAMP-or hormonally induced increase in 32P04 incorporation into desmin and vimentin was independent of protein synthesis and was not caused by stimulation of protein phosphate turnover. In addition, BrcAMP did not induce significant changes in the specific activity of the cellular ATP pool. These data suggest that the observed increase in 32P04 incorporation represented an actual increase in phosphorylation of the intermediate filament proteins desmin and vimentin. Two-dimensional tryptic analysis of desmin from 8-day-old myotubes revealed five phosphopeptides of which two showed a 7-to 10-fold increase in 32Po4 incorporation in BrcAMP-treated myotubes. Four of the phosphopeptides identified in desmin labeled in vivo were also observed in desmin phosphorylated in vitro by bovine heart cAMP-dependent protein kinase. Although phosphorylation of desmin and vimentin was apparent in myogenic cells at all stages of differentiation, BrcAMP-and isoproterenol-induced increases in phosphorylation of these proteins were restricted to mature myotubes. These data strongly suggest that in vivo phosphorylation of the intermediate filament proteins desmin and vimentin is catalyzed by the cAMP-dependent protein kinases and that such phosphorylation may be regulated during muscle differentiation.

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Desensitization of enucleated cells to hormones and role of cytoskeleton in control of normal hormonal response.

Cited by 27 publications

References 33 publications

Regulation of gene expression by tumor promoters. II. Control of cell shape and developmental programs for macrophages and granulocytes in human myeloid leukemic cells

Regulation of gene expression by tumor promoters. II. Control of cell shape and developmental programs for macrophages and granulocytes in human myeloid leukemic cells

Microtubule-disrupting agents affect two different events regulating the initiation of DNA synthesis in Swiss 3T3 cells.

Cyclic AMP-modulated phosphorylation of intermediate filament proteins in cultured avian myogenic cells.

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