Ethanolamine analogues stimulate DNA synthesis by a mechanism not involving phosphatidylethanolamine synthesis

Kiss, Zoltán; Crilly, Karan S.

doi:10.1016/0014-5793(96)00084-1

Cited by 12 publications

(11 citation statements)

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“…Ethanolamine (10), and particularly its methylated analogues (11,12), can greatly enhance insulin-induced DNA synthesis by a wortmannin-sensitive mechanism not involving PtdEtn synthesis. PMA also potentiates the mitogenic effect of insulin by a wortmannin-sensitive mechanism (9).…”

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confidence: 99%

Protein Kinase Cα Is a Major Mediator of the Stimulatory Effect of Phorbol Ester on Phospholipase D-mediated Hydrolysis of Phosphatidylethanolamine

Mukherjee

Chung

Ways

et al. 1996

Journal of Biological Chemistry

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Stimulation of phospholipase D (PLD)-mediated hydrolysis of phosphatidylcholine (PtdCho) by phorbol 12-myristate 13-acetate (PMA) has been shown to be mediated by the ␣-and ␤I-isoforms of protein kinase C (PKC). To determine the role of various PKC isozymes in the regulation of PLD-mediated phosphatidylethanolamine (PtdEtn) hydrolysis, MCF-7 human breast carcinoma cells overexpressing the ␣-and -isoforms, and R6 rat fibroblasts overexpressing the ␣-, ␤I-, and ⑀-isoforms were used. In the vector control MCF-7 cells, which contain low levels of PKC-␣, PMA (100 nM) had only small effects on the hydrolysis of PtdEtn (1.1-1.35-fold) and PtdCho (1.15-1.6-fold). Stable expression of PKC-␣ in MCF-7 cells, which was accompanied by increased levels of the ␤I-and -isoforms as well, greatly enhanced both PMA-induced PLD-mediated formation of phosphatidylethanol (ϳ5-fold) and the hydrolysis of PtdEtn (2.5-2.9-fold) and PtdCho (5.5-7.2-fold). The effects of PMA on the hydrolysis of PtdEtn (and PtdCho) in MCF-7/PKC-␣ cells were significantly inhibited by 0.5-3 M concentrations of Gö 6976, a selective inhibitor of the conventional PKC subfamily. Stable expression of PKC-␣ in R6 fibroblasts enhanced, at a shorter (10 min) incubation time, the effects of PMA on the hydrolysis of both PtdEtn and, to a lesser extent, PtdCho. In contrast, stable expression of PKC-␤I in R6 fibroblasts, which originally did not contain this enzyme, enhanced the effects of PMA only on PtdCho, but not PtdEtn, hydrolysis. Overexpression of either PKC-in MCF-7 cells or PKC-⑀ in R6 and NIH 3T3 fibroblasts had no detectable effects on PMA-induced hydrolysis of PtdEtn. Collectively, the results suggest that PKC-␣ has a major role in the mediation of phorbol ester action on PtdEtn hydrolysis, while PtdCho hydrolysis may be regulated by both the ␣ and ␤I isoforms.In many cell lines activators of phospholipase D (PLD), 1 including the protein kinase C (PKC) activator phorbol 12-myristate 13-acetate (PMA), appear to stimulate only the hydrolysis of phosphatidylcholine (PtdCho) (1, 2). In MadinDarby canine kidney cells (3) and in Swiss/3T3 cells (4) PKC-␣ was shown to be a major regulator of PtdCho hydrolysis. However, expression of PKC-␤I (5) or addition of PKC-␤I to isolated membranes (6, 7) also enhanced the effect of PMA on PtdCho hydrolysis. Interestingly, while PKC-␣ was a more effective mediator of PMA effect in lung fibroblast membranes than PKC-␤I (6), a reversed order of potency was observed in neutrophil membranes (7). Collectively, these data suggest that if expressed, both PKC-␣ and PKC-␤I may be able to regulate PtdCho hydrolysis.The role of increased PtdCho hydrolysis in the mediation of cellular actions of PKC activators is unknown. Recently, we presented evidence showing that in NIH 3T3 fibroblasts PtdCho hydrolysis is unlikely to play a major role in the mediation of mitogenic effects of PMA (8). In fact, choline phosphate, which in agonist-treated cells can be formed by the sequential actions of PLD and choline kinase, and PMA were found to sti...

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Protein Kinase Cα Is a Major Mediator of the Stimulatory Effect of Phorbol Ester on Phospholipase D-mediated Hydrolysis of Phosphatidylethanolamine

Mukherjee

Chung

Ways

et al. 1996

Journal of Biological Chemistry

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“…ethanolamines [28,29]. Considering that serum levels of Etn in 50 µM [30] (and references therein), the effects of Etn we ob-served on insulin-induced mitogenesis would require greatly ele-(ϩ1651)3′.…”

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confidence: 99%

Ethanolamine, but not Phosphoethanolamine, Potentiates the Effects of Insulin, Phosphocholine, and ATP on DNA Synthesis in NIH 3T3 Cells

Kiss

Mukherjee

Crilly

et al. 1997

European Journal of Biochemistry

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NIH 3T3 fibroblasts express a phospholipase D activity hydrolyzing phosphatidylethanolamine (PtdEtn) which produces ethanolamine (Etn) in response to a variety of growth regulating agents. The main objective of this work was to evaluate the effects of Etn on mitogenesis and to determine whether these effects require its metabolism to phosphoethanolamine (PEtn) or PtdEtn. To increase conversion of Etn to PEtn, an Etn-specific kinase derived from Drosophila was highly expressed in NIH 3T3 cells. Overexpression of this Etn kinase resulted in large (10Ϫ12.5-fold) increases in PEtn formation, but only in modest (1.2Ϫ1.7-fold) increases in PtdEtn synthesis. In both vector control and Etn kinase overexpressor cells, Etn had biphasic effects on insulin-induced DNA synthesis with maximal (Ϸ2-fold) potentiating effects being observed at 0.5Ϫ1 mM concentrations, followed by an inhibitory phase at higher Etn concentrations. In the Etn kinase overexpressor lines, the inhibitory phase was elicited by lower Etn concentrations and it was partially blocked by 5 mM choline due to decreased formation of PEtn. In both vector control and Etn kinase overexpressor cells, phosphocholine (PCho) and insulin synergistically stimulated DNA synthesis; their effects were further enhanced by physiologically relevant (5Ϫ60 µM) concentrations of Etn by a mechanism independent of mitogen-activated protein (MAP) kinase. Concentrations of Etn Ͼ 50 µM also enhanced the effects of both PCho and the synergistic effects of PCho plus ATP; however, in the latter case 20 µM Etn was inhibitory. The magnitude of both the potentiating and inhibitory effects of Etn on PCho-induced as well as PCho ϩ ATP-induced DNA synthesis were similar in the vector control and Etn kinase overexpressor cells; they were associated with stimulation and inhibition, respectively, of p42 MAP kinase activity. The results indicate that in NIH 3T3 cells Etn exerts significant effects on DNA synthesis which, except inhibition of insulin-induced DNA synthesis by higher concentrations of Etn, do not correlate with the metabolism of Etn to PEtn or PtdEtn.Keywords : DNA synthesis; ethanolamine; phosphoethanolamine; insulin; mitogen-activated-protein kinase.Most mammalian cells express phospholipase D (PLD) [1Ϫ work from our laboratory has shown that PCho at physiological concentrations acts as a potent mitogen via an extracellular site 3] and phospholipase C [4Ϫ9] activities specific for phosphatidylcholine (PtdCho) which play important roles in the formation in the presence of ATP, insulin, or sphingosine 1-phosphate [11].A PLD activity, capable of generating ethanolamine (Etn) of the lipid messengers phosphatidic acid and 1,2-diacylglycerol. Another biologically active metabolite of PtdCho is phos-from phosphatidylethanolamine (PtdEtn), also has been iden- sources.E-mail: kissx001@maroon.tc.umn.edu Abbreviations. PtdCho, phosphatidylcholine ; PCho, phosphochoIt has recently been reported by two laboratories that yeast line; Etn, ethanolamine; PtdEtn, phosphatidylethanolamine; PEtn, ph...

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“…Similarly, DEA protected hematopoietic progenitor cells and murine L1210 leukemia cells from cytotoxicity of the chemotherapeutic agent mechlorethamine (28). Moreover, DEA promoted DNA synthesis of NIH-3T3 fibroblast cells in serum-free conditions, and both DEA and MEA enhanced insulin-induced DNA synthesis (29). However, it should be noted that, in these studies, the effects of MEA and DEA were examined at very high concentrations (at the mM range) and in different cell types.…”

Section: Discussionmentioning

confidence: 96%

“…Several studies have demonstrated protection against apoptosis by the methylated EA analogues MEA and DEA (27)(28)(29). Therefore, we examined the effect of these methyl derivatives of EA on low serum-induced apoptosis.…”

Section: Metabolism Of Aea To Ethanolamine Is a Criticalmentioning

confidence: 99%

Anandamide Protects from Low Serum-induced Apoptosis via Its Degradation to Ethanolamine

Matas

Juknat²,

Pietr

et al. 2007

Journal of Biological Chemistry

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Anandamide (AEA) is a lipid molecule belonging to the family of endocannabinoids. Various studies report neuroprotective activity of AEA against toxic insults, such as ischemic conditions and excitotoxicity, whereas some show that AEA has pro-apoptotic effects. Here we have shown that AEA confers a protective activity in N18TG2 murine neuroblastoma cells subjected to low serum-induced apoptosis. We have demonstrated that the protection from apoptosis by AEA is not mediated via the CB1 receptor, the CB2 receptor, or the vanilloid receptor 1. Interestingly, breakdown of AEA by fatty acid amide hydrolase is required for the protective effect of AEA. Furthermore, the ethanolamine (EA) generated in this reaction is the metabolite responsible for the protective response. The elevation in the levels of reactive oxygen species during low serum-induced apoptosis is not affected by AEA or EA. On the other hand, AEA and EA reduce caspase 3/7 activity, and AEA attenuates the cleavage of PARP-1. Taken together, our results demonstrate a role for AEA and EA in the protection against low seruminduced apoptosis.Arachidonoyl ethanolamide (also named anandamide or AEA) 3 is a well known member of a family of endogenous lipid mediators termed endocannabinoids. A wide range of physiological functions of endocannabinoids was discovered in recent years. It appears that the endocannabinoids play crucial roles in the central and autonomous nervous system, the reproductive system, the cardiovascular system, the gastrointestinal tract, and in microcirculation (1).The endocannabinoids, as well as plant-derived and synthetic cannabinoids, were shown to activate two distinct G protein-coupled cannabinoid receptors, the CB1 receptor, which is present at high concentrations in the nervous system, and the CB2 receptor, which is located primarily in immune cells (2). The endocannabinoid AEA is also capable of activating the vanilloid receptor 1 (VR1) (3). However, both cannabinoids and endocannabinoids were found to affect various physiological functions by mechanisms that are not dependent upon the receptor subtypes with which they are known to interact.Evidence has accumulated in recent years in support of involvement of cannabinoids in the modulation of cell faterelated processes, such as proliferation, death, and differentiation (4 -6). Some studies report protective activity of the endocannabinoid AEA against apoptosis, whereas others describe AEA as an apoptosis inducer (4). AEA was shown to induce apoptosis in cell lines from different origins, including neuronal cells (7). Pro-apoptotic activity of AEA was documented in primary neurons, in PC-12 pheochromocytoma cells, and in CHP-100 neuroblastoma cells (8 -10). On the other hand, neuroprotective activities of AEA have been implicated in various pathological conditions. For example, AEA protects cultured cerebral cortical neurons from the effects of a combination of hypoxia and glucose deprivation, conditions serving as an in vitro model of ischemia (11), and Milton has demonstrated inh...

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Ethanolamine analogues stimulate DNA synthesis by a mechanism not involving phosphatidylethanolamine synthesis

Cited by 12 publications

References 19 publications

Protein Kinase Cα Is a Major Mediator of the Stimulatory Effect of Phorbol Ester on Phospholipase D-mediated Hydrolysis of Phosphatidylethanolamine

Protein Kinase Cα Is a Major Mediator of the Stimulatory Effect of Phorbol Ester on Phospholipase D-mediated Hydrolysis of Phosphatidylethanolamine

Ethanolamine, but not Phosphoethanolamine, Potentiates the Effects of Insulin, Phosphocholine, and ATP on DNA Synthesis in NIH 3T3 Cells

Anandamide Protects from Low Serum-induced Apoptosis via Its Degradation to Ethanolamine

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