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Pariente F, Prasad V, Ludueña RF, Manso-Martínez R. Effects of ATP and cyclic AMP on the in vitro assembly and stability of mammalian brain microtubules. Mol Cell Biochem 1987; 74:43-54. [PMID: 3035363 DOI: 10.1007/bf00221911] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
The relevance of protein phosphorylation, transphosphorylation and binding phenomena in the kinetics of the ATP-induced assembly of cycle-purified microtubule protein from mammalian brain were studied. ATP was able to induce the polymerization of microtubules of normal appearance. However, the assembled structures, were unstable and microtubules depolymerized after achievement of a transitory maximum. Cyclic AMP reduced the amplitude of the polymerization maximum in a concentration-dependent manner, correlating with the stimulation of the endogenous phosphorylation reaction. When microtubule assembly was induced by GTP, in the presence of various concentrations of ATP, the slope of the depolymerization phase was found to depend on the concentration of ATP. Fluoride ion inhibited the endogenous phosphorylation reaction and reduced the disassembly rate, in a concentration-dependent manner. Evidence is also presented indicating that ATP did not bind to phosphocellulose-purified tubulin. These results further contribute to indicate that ATP and cyclic AMP, acting coordinately to control the phosphorylation extent of microtubule proteins are important factors to determine microtubule stability within the cell. Some implications of this mechanism for the regulation by cAMP of the initiation of DNA synthesis and mitosis are considered.
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Manso-Martínez R, Palomares R, Pariente F. Mammalian brain microtubules are sensitive to cyclic AMP in vitro. Arch Biochem Biophys 1984; 235:196-203. [PMID: 6093708 DOI: 10.1016/0003-9861(84)90268-6] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Microtubules assembled in vitro with ATP were depolymerized by the addition of cyclic AMP, which correlates with a stimulation of the endogeneous phosphorylation reaction. When assembled with GTP, however, microtubules were only sensitive to cyclic AMP when ATP was present. This nucleoside triphosphate induced the disassembly of microtubules in a concentration-dependent, cyclic nucleotide-stimulated manner. Since UTP, CTP and the nonhydrolyzable ATP analog adenosine-5'-(beta, gamma-methylene)triphosphate were without comparable effect, it was assumed that phosphorylation of the microtubule-associated proteins may represent a physiological mechanism by which microtubules in the living cell respond to external stimuli.
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Wang ZW, Rozengurt E. Interplay of cyclic AMP and microtubules in modulating the initiation of DNA synthesis in 3T3 cells. J Cell Biol 1983; 96:1743-50. [PMID: 6189842 PMCID: PMC2112466 DOI: 10.1083/jcb.96.6.1743] [Citation(s) in RCA: 29] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
The results presented here show that disruption of the microtubule network acts synergistically with cAMP-elevating agents to stimulate the entry into DNA synthesis of 3T3 cells. Antimicrotubule agents and increased cAMP levels require an additional growth-promoting factor for inducing initiation of DNA synthesis; such requirement can be furnished by insulin, vasopressin, epidermal growth factor, platelet-derived growth factor, or fibroblast-derived growth factor. The involvement of the microtubules is indicated by the fact that enhancement of the DNA synthetic response was demonstrated with the chemically diverse agents colchicine, nocodazole, vinblastine, or demecolcine, all of which elicited the response in a dose-dependent manner. We verified that colchicine and nocodazole, at the doses used in this study, induced microtubule disassembly in the absence as well as in the presence of cAMP-elevating agents as judged by measurement of [3H]colchicine binding of total and pelletable tubulin. The involvement of cAMP was revealed by increasing its endogenous production by cholera toxin or by treatment with 8BrcAMP. The enhancing effects of antimicrotubule drugs and cAMP-elevating agents could be demonstrated by incorporation of [3H]thymidine into acid-insoluble material, autoradiography of labeled nuclei, or flow cytofluorometric analysis. The addition of antimicrotubule drugs does not increase the intracellular level of cAMP nor does addition of cAMP-elevating agents promote disassembly of microtubules (as judged by measuring [3H]colchicine binding of total and pelletable tubulin) in 3T3 cells. In view of these findings and the striking synergistic effects between these agents in stimulating DNA synthesis in the presence of a peptide growth factor, we conclude that increased cAMP levels and a disrupted microtubule network regulate independent pathways involved in proliferative response.
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Niles R, Loewy B, Krah D. Temperature-dependent alteration of cellular morphology by cholera toxin in rat liver epithelial cells which are ts for maintenance of transformed properties. J Cell Physiol 1982; 113:35-9. [PMID: 6290511 DOI: 10.1002/jcp.1041130108] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Cholera toxin via its ability to increase intracellular cyclic AMP levels can induce drastic changes in cell morphology. This report describes a temperature sensitive mutant of chemically transformed rat liver epithelial cells which only display cell shape alterations in response to cholera toxin at the permissive temperature. Shift up-shift down experiments indicate that the change in the response occurs fairly rapidly, i.e., within 2 hours at the new temperature. The behavior of the temperature sensitive cells at the nonpermissive temperature mimics that of the untransformed rat liver epithelial cells (i.e., no morphological change in response to cholera toxin) while at the permissive temperature the positive cell shape change is identical to that exhibited by chemically transformed rat liver epithelial cells. The temperature sensitive response to cholera toxin is not a function of cyclic AMP production, since the amount of cyclic AMP found as a function of either time or concentration of cholera toxin is quite similar in cells treated at either temperature.
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Ledinko N, Schaeufele J, Chen C. Adenovirus type 12 transformation involves loss of beta-adrenergic receptors and isoproterenol responsiveness. Mol Cell Biol 1982; 2:805-14. [PMID: 6152838 PMCID: PMC369863 DOI: 10.1128/mcb.2.7.805-814.1982] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
The responsiveness of a growth-regulated rat 3Y1 cell line and five clones of 3Y1 cells transformed by the highly oncogenic human adenovirus type 12 to the catecholamine hormone (-)-isoproterenol was studied. The untransformed cells contained beta-adrenergic receptors characterized by specific binding of the beta-adrenergic receptor antagonist (-)-[3H]dihydroalprenolol, a 9- to 12-fold increase in cyclic AMP production in intact cells after incubation with 10 microM (-)-isoproterenol, and significantly increased adenylate cyclase (ATP pyrophosphatelyase [cyclizing], EC 4.6.1.1) activity in the presence of the hormone. In contrast, (-)-isoproterenol (10 to 100 microM) had no apparent effect on cyclic AMP production or the basal adenylate cyclase activity in the transformed cell lines. Binding studies revealed that untransformed cells contained approximately 19,400 beta-adrenergic receptor sites per cell. Three transformed cell clones tested showed a three- to fourfold loss of beta-adrenergic receptors.
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Dore-Duffy P. Differential effect of prostaglandins and other products of arachidonic acid metabolism on measles virus replication in Vero cells. PROSTAGLANDINS, LEUKOTRIENES, AND MEDICINE 1982; 8:73-82. [PMID: 6281810 DOI: 10.1016/0262-1746(82)90129-9] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
The influence of cyclic adenosine 3', 5'-monophosphate (cAMP) and prostaglandin (PG), E1, E2, F2 alpha, A2 and thromboxane B2 (TxB2) and measles virus infection was investigated. Addition of PGE1, E2 and cAMP (10(-3)-10(-)8M) inhibited measles virus replication in Vero cells. TxB2 and PGA2 enhanced replication. Cytotoxic effects were not observed. Inhibition of infectious titers (98%) was most pronounced when agents were present throughout replication. Treated cells exhibited hemadsorbing antigen, but the size and number of cytoplasmic inclusions was decreased by cAMP. Pre-treatment of cells with PGE1 or presence of PGE1 during virus adsorption enhanced infectious titers (30%). Results suggest that cAMP and PGE1 inhibit measles virus production infection. That both enhancing and inhibiting effects of PGs were seen suggest that measles virus may require PG at specific times during the replicative cycle.
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Puck TT, Erikson RL, Meek WD, Nielson SE. Reverse transformation of vole cells transformed by avian sarcoma virus containing the src gene. J Cell Physiol 1981; 107:399-412. [PMID: 6265480 DOI: 10.1002/jcp.1041070312] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Vole cells transformed by avian sarcoma virus carrying the src gene lose their fibroblastic morphology, the organized cytoskeletal system of the normal fibroblastic cell, the typical fibronectin deposit around the cell membrane, and the ability to shut off multiplication when suspended in liquid medium. All of these transformation characteristics are reversed by treatment with cAMP derivatives. Moreover, the cAMP treatment does not cause loss of activity of the src gene product. These data imply that cAMP exerts its effect at or after the point in the metabolic pathway affected by the src gene product, pp60src. Presumably, the decision to adopt the transformed or the normal state is determined by the degree to which the src gene or cAMP-mediated kinase activities respectively predominante in the cell. The development of all four transformation characteristics as a result of introduction of the src gene, and their coordinate reversal by cAMP derivatives, supports the previous thesis that in the normal vole or CHO fibroblast all four properties are part of a common regulatory system.
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Somers KD. Increased cyclic AMP content directly correlated with morphological transformation of cells infected with a temperature-sensitive mutant of mouse sarcoma virus. IN VITRO 1980; 16:851-8. [PMID: 6252097 DOI: 10.1007/bf02619422] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Normal rat kidney cells infected with a cold-sensitive mutant of mouse sarcoma virus [NRK(MSV-lb)] morphologically transform when exposed to adenosine 3':5' cyclic monophosphate (cAMP) at the restrictive temperature. The cAMP-induced morphological changes occur rapidly and are reversible. Agents capable of elevating endogenous levels of cAMP [prostaglandin E1 (PGE1) and cholera toxin (CT)] induced morphological transformation of NRK(MSV-lb) cells at the restrictive temperature that was concentration dependent, potentiated by cAMP phosphodiesterase inhibitors, and not prevented by inhibitors of DNA, RNA, and protein synthesis. Prostaglandin E1 stimulated a transient increase in the intracellular level of cAMP with a concomitant morphological transformation and reversion of cells as cAMP levels decline. The maximum increase is reached by 10 min, followed by a decline to near basal level by 80 min. In contrast, incubation of cells with CT resulted in irreversible morphological transformation and increased levels of cAMP first detectable by 1 hr with maximum levels reached by 24 hr. Heated CT (100 degrees C, 20 min) was without effect. Addition of CT to reverted PGE1-treated cells resulted in morphological transformation suggesting the existence of discrete receptors in NRK(MSV-lb) cells.
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Robert J, Mandel P, Rebel G. Membrane lipids in bromodeoxyuridine-differentiated astroglial cells in culture. Lipids 1979; 14:852-9. [PMID: 502763 DOI: 10.1007/bf02534128] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Embryonic hamster astroblasts (NN strain) grown in continuous line were cultivated in the presence of bromodeoxyuridine (BrdU). A decrease in the growth rate of the cells and striking changes in their morphology were observed, the morphology of the cells resembling that of mature astrocytes. Membrane lipids of BrdU-differentiated and standard cells were compared. No modification of the lipid/protein ratio was observed. Phospholipids and cholesterol were increased in the same proportions in the cells, and no modification of the phospholipid distribution was observed. Ganglioside sialic acid remained at the same level, but the ganglioside distribution was highly modified. Complex gangliosides appeared (GM1 and GD1a), while the proportion of simple gangliosides (GM3 and GD3) decreased. However, neither GT1 nor GQ1 were detected in differentiated cells. The distribution of phosphoglyceride acyl groups was highly modified, the proportion of arachidonic and docosapentaenoic acids being 2 to 3 times higher in BrdU-treated cells than in proliferating ones. These results were compared to those obtained with another clonal line of glial cells (C6) which exhibited no morphological differentiation in the presence of BrdU; the lipids of these cells were not modified by such a treatment.
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Hunt NH, Martin TJ. Cyclic nucleotide metabolism in tumours. AUSTRALIAN AND NEW ZEALAND JOURNAL OF MEDICINE 1979; 9:584-99. [PMID: 231426 DOI: 10.1111/j.1445-5994.1979.tb03401.x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Many hormones act by combining with cell surface receptors and stimulating adenylate cyclase activity. The cyclic AMP generated is the mediator of a number of cellular metabolic processes. Other processes may be influenced by changes in cyclic GMP levels. Although much evidence from cultured cells suggested that low cellular levels of cyclic AMP and high levels of cyclic GMP are a feature of rapid cell growth and of malignant transformation, review of the data reveals many inconsistencies. Thus in established tumours growing in vivo, for example, cyclic AMP levels appear to be unrelated to tumour growth rates. It seems that tumour cell cyclic AMP is more likely concerned with the regulation of tumour cell function than of growth. This would have implications for therapy, in that drugs which influence cyclic nucleotide metabolism could influence tumour cell function. The control of cyclic nucleotide production in normal and tumour cells is discussed, together with the possible ways in which abnormalities of this may occur.
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Meza AT, Rieber M. Dibutyryladenosine 3':5'-cyclic monophosphate-mediated changes in rat cells involve macromolecular alterations in vinblastine-precipitable proteins. Biochem J 1978; 174:1071-4. [PMID: 215120 PMCID: PMC1186015 DOI: 10.1042/bj1741071] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
ts-NT3-KR rat cell cultures show the loss of three components in the molecular-weight region 200,000--250,000 when exposed to dibutyryl cyclic AMP, under conditions of both restriction and expression of the transformed phenotype. Vinblastine is able to precipitate preferentially from control cultures the species that are decreased by exposure to the cyclic nucleotide. Serum-starved cultures exposed to dibutyryl cyclic AMP reveal differences in their vinblastine precipitates, depending on whether the expression of the transformation phenotype is restricted or not.
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Pastan I, Willingham M. Cellular transformation and the 'morphologic phenotype' of transformed cells. Nature 1978; 274:645-50. [PMID: 209337 DOI: 10.1038/274645a0] [Citation(s) in RCA: 122] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Expression of the product of the transforming gene (src) of RNA tumour viruses promotes growth and usually alters the adhesion, appearance and surface properties of cultured fibroblasts. The latter group of properties termed the 'morphologic phenotype' of transformed cells is largely due to diminished cell-to-substratum adhesion. The role of cyclic AMP, cell surface protein (CSP), and other factors in producing the 'morphologic phenotype' are discussed. The effects of src expression bear a striking resemblance to the action of peptide hormones such as insulin on appropriate target cells.
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Schlegel R, Benjamin TL. Cellular alterations dependent upon the polyoma virus Hr-t function: separation of mitogenic from transforming capacities. Cell 1978; 14:587-99. [PMID: 210955 DOI: 10.1016/0092-8674(78)90244-1] [Citation(s) in RCA: 88] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Hr-t mutants of polyoma virus are restricted in their growth properties (host range) and defective in cell transformation and tumor induction. The present study indicates that these mutants have lost the ability to induce morphological transformation, but have retained a mitogenic function. Thus an early and dramatic difference between wild-type virus and hr-t mutant-infected cultures of rat fibroblasts is the morphological change in individual cells observed by light, fluorescence and scanning electron microscopy. Viruses containing an intact hr-t function (wild-type virus and ts-a mutants) induce a transformed phenotype consisting of stellate cell shape, loss of defined cytoplasmic actin architecture, cellular "underlapping," and increased nuclear and nucleolar sizes. These prominent alterations constitute an abortive transformation, peaking 24-48 hr post-infection, and subsequently resolving in most or all of the cells. In contrast, cells infected with hr-t mutants do not develop the above structural changes, but rather retain their preinfection appearance. Both wild-type virus and hr-t mutants induce cellular DNA synthesis in confluent monolayers of rat cells beginning 12-14 hr post-infection. Flow microfluorometric (FMF) analysis confirms the viral mediated transit of cells from the G1 to the S and G2 phases of the cell cycle, as well as an increase in the proportion of cells with an 8N (octaploid) DNA content. Approximately 50% of the clones isolated from wild-type-infected cultures are polyploid. Stable transformants are found among these polyploid clones, but the majority of the latter resemble the parental cells in their morphology and growth properties. Polyploid clones are derived from hr-t mutant-infected cultures at a much lower frequency, similar to that of mock-infected cultures. Data obtained by sequential labeling of infected cultures with 3 H-thymidine and 5-bromo-deoxyuridine, together with cell number quantitation, indicate that hr-t mutants promote only a single round of cell division, while the wild-type virus and ts-a mutants promote multiple rounds. Loss of the hr-t function in polyoma virus therefore reveals a residual viral mitogenic activity, but prevents the virus from effecting morphological transformation of cells with concomitant loss of defined actin cables, polyploidization and multiple cycles of cell division in confluent cultures.
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