Cell cycle specific fluctuations of adenosine 3',5' -monophosphate and prostaglandin binding in synchronized mastocytoma P-815 cells

Cyclic AMP affinity purification and ESI-QTOF MS-MS identification of cytosolic glyceraldehyde 3-phosphate dehydrogenase and two nucleoside diphosphate kinase isoforms from tobacco BY-2 cells

The soluble protein fraction of tobacco bright yellow 2 cells contained adenosine 3',5'-cyclic monophosphate (cAMP)-binding activity, detected with both a conventional binding assay and a surface plasmon resonance biosensor. A cAMP-agarose-based affinity purification procedure yielded three proteins which were identified by mass spectrometry as glyceraldehyde 3-phosphate dehydrogenase (GAPDH) and two nucleoside diphosphate kinases (NDPKs). This is the first report describing an interaction between cAMP and these proteins in higher plants. Our findings are discussed in view of the reported role of the interaction of cAMP with GAPDH and NDPK in animals and yeast. In addition, we provide a rapid method to isolate both proteins from higher plants.

Effect of indomethacin on cell cycle dependent cyclic AMP fluxes in tobacco BY-2 cells

The evolution of adenosine 3',5'-cyclic monophosphate (cAMP) levels was investigated in synchronised tobacco BY-2 cells by virtue of a method based on immunoaffinity purification and analysis on electrospray tandem mass spectrometry. A transient peak in cAMP content was observed during the S and G1 phases of the cell cycle. Application of the prostaglandin inhibiting drug indomethacin at early S phase resulted in the loss of the cAMP peak in S phase and inhibited mitotic division. This inhibition of cAMP accumulation suggests the presence of a prostaglandin-dependent adenylyl cyclase activity, analogous to animal cyclases. A potential role for cAMP during the plant cell cycle is postulated.

Synergistic effects of cyclic AMP and Ca2+ ionophore A23187 on de novo synthesis of histidine decarboxylase in mastocytoma P-815 cells

In the preceding paper (Kawai, H. et al. (1992) Biochim. Biophys. Acta 1133, 172-178), we reported that in mastocytoma P-815 cells dexamethasone and 12-O-tetradecanoylphorbol-13-acetate (TPA) synergistically enhanced the de novo synthesis of L-histidine decarboxylase (HDC). Here we found that Ca2+ acted synergistically with cAMP in the induction of HDC mRNA and HDC activity in mastocytoma P-815 cells, and that the mechanism underlying the enzyme induction by Ca2+ plus cAMP was distinguishable from that by dexamethasone plus TPA. Ca2+ ionophore A23187, itself having no significant activity, markedly enhanced the induction of HDC activity by N6,O2'-dibutyryl cAMP (db cAMP) or cAMP-inducible prostaglandins such as PGE1, PGE2 and PGI2 in the presence of the phosphodiesterase inhibitor, Ro201724. However, A23187 had little effect on increases in HDC activity induced by other known stimulants, such as TPA, dexamethasone and sodium butyrate. These results suggest that A23187 has a specific effect on the induction of HDC activity due to an increased level of cAMP. The finding that both A23187 and cAMP enhanced HDC activity suggests that both Ca2+/calmodulin and cyclic nucleotide dependent protein kinase play essential roles in the process of enhancement of HDC activity. To examine this possibility, we studied the effects of W-7, an inhibitor of calmodulin, removal of extracellular Ca2+, and H-8, an inhibitor of cAMP-dependent protein kinase, on the enhancing activity of A23187 plus db cAMP. The enhancement of HDC activity by A23187 plus db cAMP was inhibited by W-7, removal of extracellular Ca2+, and H-8. The increase in HDC activity was due to the de novo synthesis of the enzyme, since it was suppressed by the addition of cycloheximide or actinomycin D, and was well correlated with the marked accumulation of a 2.7 kilobase HDC mRNA. Furthermore, the mechanism underlying the induction of HDC by db cAMP plus A23187 is distinguishable from that in the case of dexamethasone plus TPA, since preexposure to dexamethasone plus TPA for 12 h, for a plateau level to be reached, did not affect the subsequent increase in HDC activity due to db cAMP plus A23187.

Inhibitors of lipoxygenase have antiproliferative effects on P815 murine mastocytoma cells

The effect of a variety of inhibitors of prostaglandin synthase, lipoxygenase and phospholipase on the growth of P815 murine mastocytoma cells was examined. Only lipoxygenase inhibitors substantially reduced growth, presumably by inhibiting the production of arachidonic acid metabolites rather than causing arachidonate accumulation since excess arachidonic acid did not reverse growth inhibition. Evidence is presented that production of leukotrienes B4, C4, D4 or E4 was not involved. Other metabolites of arachidonic acid were not excluded. A role for lipoxygenase in growth signal transduction in these and other cells is suggested.

Independent regulation of pyruvate kinase expression by cyclic AMP and prostaglandin F2 alpha in mouse mastocytoma cells

P-815 mouse mastocytoma cells express the K isozyme of pyruvate kinase and the specific activity of this enzyme is increased in response to N6,2'-O-dibutyryladenosine 3':5'-cyclic monophosphate, 8-bromoadenosine 3':5'-cyclic monophosphate, cholera toxin, and epinephrine, all of which also elevate the intracellular concentration of adenosine 3':5'-cyclic monophosphate. Prostaglandin F2 alpha also increases the cellular activity of this enzyme, but does not increase the adenosine 3':5'-cyclic monophosphate levels. Under all these conditions, the increase in enzymatic activity is accompanied by an equivalent increase in the pyruvate kinase protein level. However, neither the rate of enzyme synthesis nor the level of pyruvate kinase mRNA is elevated by N6,2'-O-dibutyryladenosine 3':5'-cyclic monophosphate. On the other hand, it does increase the enzyme's half-life. In contrast, prostaglandin F2 alpha increases the rate of synthesis and the level of pyruvate kinase K mRNA, but has no influence on the rate of degradation. Therefore, these cells have two mechanisms which increase pyruvate kinase K levels. One operates via an increase in cAMP level and results in a decrease in the rate of degradation, whereas the other minimizes an upsurge in cAMP levels but still increases pyruvate kinase K activity by increasing its rate of synthesis.

Cyclic-AMP-induced c-fos expression and its relevance to differentiation of a transformed mast cell line

The effects of cyclic AMP on expression of the oncogenes c-myc, c-myb and c-fos in murine P815 mastocytoma cells were examined in relation to growth and differentiation. Induction of differentiation in mastocytoma cells by cyclic AMP was accompanied by a rapid increase in c-fos expression. Cyclic AMP induced stable expression of c-fos mRNA by increasing c-fos transcription 4-5-fold and slightly increasing the stability of c-fos mRNA. However, a high level of c-fos expression was not essential for differentiation of two temperature sensitive-mutant P815 cell lines, as c-fos mRNA did not increase in differentiating temperature-sensitive P815 cells. These results do not support an essential role for c-fos expression in the differentiation of mast cells. Although c-myc expression was lower after growth arrest by cyclic AMP, this decrease did not correlate with growth inhibition by cyclic AMP, since c-myc expression decreased only after cells had started to arrest in G1 phase.

Inhibitory effect of tritoqualine (TRQ) on histamine release from mast cells

Tritoqualine (TRQ), used clinically as an antiallergic drug, did not inhibit histidine decarboxylase activity (HDC, EC. 4.1.1.22.) partially purified from fetal rats and the enzymes prepared from mastocytoma P-815 cells. However, TRQ inhibited the histamine release from rat peritoneal mast cells induced by compound 48/80 and ATP. TRQ was also effective in inhibiting antigen-induced histamine release in rat mast cells sensitized actively or passively by the homologous anti-DNP-Ascaris antibody. Preincubation of cultured mastocytoma P-815 cells in a medium including TRQ inhibited non-cytotoxically the histamine release of mastocytoma cells induced by compound 48/80, and the effect of TRQ became more marked with lengthening of the culture period in the presence of TRQ. It was concluded from these results that one of the main actions of TRQ as an antiallergic drug was not the inhibitory action on HDC, but might be ascribed to its inhibitory effect on histamine release from mast cells.

Regulation of pyruvate kinase expression and growth in P-815 mastocytoma cells. II. Potential role of prostaglandins

P-815 mastocytoma cells increase the level of pyruvate kinase (PK) expression in response to chloroform-methanol extracts of conditioned media, butyrate, and dibutyryl cyclic AMP (but2cAMP) plus theophylline. The butyrate effect is indomethacin sensitive, suggesting a prostaglandin (PG) is the active signaling factor. Moreover, the chloroform-methanol extracts contain PGE2 and PGF2 alpha and additions of the latter enhance PK activity. PGE2 alone has little or no effect but acts synergistically with PGF2 alpha. These data show that PGF2 alpha can regulate PK levels. On the other hand, other factors may also be active, since the endogeneous and the but2cAMP plus theophylline effects are indomethacin insensitive. Most of the factors that increase PK activity also inhibit cellular growth; however, regulation of PK expression can be uncoupled from growth inhibition.

Regulation of pyruvate kinase expression and growth in mastocytoma cells. I. Initial observations

The specific activities of pyruvate kinase and phosphofructokinase but not lactate dehydrogenase increase as P-815 mastocytoma cells approach the stationary phase. During this growth period, the rates of uptake of labelled precursors into DNA, RNA and total protein decreases. On the other hand, the pyruvate kinase protein level changes in parallel with activity. Although the K-isozyme is the primary form of pyruvate kinase expressed, some M-type subunit is also present and both forms undergo an increase in specific activity. In addition, pyruvate kinase expression is also elevated by adding cAMP analogues with theophylline, butyrate or conditioned media. This increased level of expression is hypothesized to be a secondary event associated with a differentiation-like-induced expression of the mast cell phenotype.

Calcium uptake in mastocytoma P-815 cells

Kinetic data of 45Ca2+ exchange in exponentially growing mastocytoma P-815 cells at 37 degree C indicated the presence of at least two calcium compartments, fast and slowly exchangeable. The fast phase of calcium exchange at the cell surface had a rate constant of 36.1 min-1 and a compartment size of 8.27 nmol/10(6) cells, while the slow phase, the intracellular calcium exchange, showed a rate constant of 2.4 min-1 and a compartment size of 0.53 nmolS/10(6) cells. The fast phase comprised two calcium binding sites of high and low affinities with dissociation constants of 0.59 and 4.88 mM, respectively, and binding maxima of 5.15 and 34.4 nmol/10(6) cells, respectively. The calcium uptake at both binding sites was inhibited by 80% on the addition of ruthenium red (0.4 mM) or lanthanum chloride (0.5 mM), but not by tetracaine (5 mM). The high-affinity site had two negative reaction enthalpy changes, delta H 0 = -1.55 (from 0 to 22 degree C) and -4.27 (from 22 degree C to 37 degree C) kcal . mol-1, while the low-affinity site showed two positive reaction enthalpy changes, delta H0 = +6.53 (below 22 degree C) and +2.05 (above 22 degree C) kcal . mol-1, suggesting the effect of membrane fluidity on calcium binding. The slow phase of calcium exchange was also inhibited by ruthenium red and lanthanum chloride resulting in a decrease of the Hill's coefficient from 1.70 to 1.28 and 1.13, respectively, but was not affected by tetracaine. Calcium efflux from 45 Ca-loaded cells was also inhibited by ruthenium red and lanthanum chloride and was also temperature sensitive. The efflux rate constant was reduced by 80% and 100% at 20 degree C and 0 degree C, respectively. As calcium uptake fluctuated during the cell cycle of synchronous mastocytoma P-815 cells with a peak at the mid S phase and the lowest level during the late M phase, the compartment size of fast phase also fluctuated, being highest at the S phase and lowest at the M phase. In contrast, the compartment size of the slow phase was highest at the G1 phase and lowest at the M phase. In parallel with these changes, the binding maximum of the high-affinity site was highest at the S phase and lowest at the M phase, while that of the low-affinity site fluctuated little throughout the cell cycle.