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Karmakar P, Gaitonde V. Promising Recent Strategies with Potential Clinical Translational Value to Combat Antibacterial Resistant Surge. MEDICINES (BASEL, SWITZERLAND) 2019; 6:E21. [PMID: 30709019 PMCID: PMC6473725 DOI: 10.3390/medicines6010021] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/06/2018] [Revised: 01/10/2019] [Accepted: 01/26/2019] [Indexed: 12/27/2022]
Abstract
Multiple drug resistance (MDR) for the treatment of bacterial infection has been a significant challenge since the beginning of the 21st century. Many of the small molecule-based antibiotic treatments have failed on numerous occasions due to a surge in MDR, which has claimed millions of lives worldwide. Small particles (SPs) consisting of metal, polymer or carbon nanoparticles (NPs) of different sizes, shapes and forms have shown considerable antibacterial effect over the past two decades. Unlike the classical small-molecule antibiotics, the small particles are less exposed so far to the bacteria to trigger a resistance mechanism, and hence have higher chances of fighting the challenge of the MDR process. Until recently, there has been limited progress of clinical treatments using NPs, despite ample reports of in vitro antibacterial efficacy. In this review, we discuss some recent and unconventional strategies that have explored the antibacterial efficacy of these small particles, alone and in combination with classical small molecules in vivo, and demonstrate possibilities that are favorable for clinical translations in near future.
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Affiliation(s)
- Partha Karmakar
- Department of Radiology, Washington University School of Medicine, St. Louis, MO 63110, USA.
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Xiong MH, Li YJ, Bao Y, Yang XZ, Hu B, Wang J. Bacteria-responsive multifunctional nanogel for targeted antibiotic delivery. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2012; 24:6175-6180. [PMID: 22961974 DOI: 10.1002/adma.201202847] [Citation(s) in RCA: 193] [Impact Index Per Article: 16.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/14/2012] [Revised: 08/15/2012] [Indexed: 06/01/2023]
Abstract
Bacteria-Responsive Multifunctional Nanogel: We developed a bacteria-responsive multifunctional nanogel for targeted antibiotic delivery, in which bacterial enzymes are utilized to trigger antibiotic release by degrading the polyphosphoester core. The mannosylated nanogel preferentially delivers drugs to macrophages and leads to drug accumulation at bacterial infection sites through macrophage transport. This nanogel provides macrophage targeting and lesion site-activatable drug release properties, which enhances bacterial growth inhibition.
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Affiliation(s)
- Meng-Hua Xiong
- CAS Key Laboratory of Soft Matter Chemistry and Department of Polymer Science and Engineering, University of Science and Technology of China, Hefei, Anhui 230026, P. R. China
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Riebeling C, Morris AJ, Shields D. Phospholipase D in the Golgi apparatus. Biochim Biophys Acta Mol Cell Biol Lipids 2009; 1791:876-80. [PMID: 19376267 DOI: 10.1016/j.bbalip.2009.04.003] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2009] [Revised: 04/06/2009] [Accepted: 04/09/2009] [Indexed: 12/18/2022]
Abstract
Phospholipase D has long been implicated in vesicle formation and vesicular transport through the secretory pathway. The Golgi apparatus has been shown to exhibit a plethora of mechanisms of vesicle formation at different stages to accommodate a wide variety of cargo. Phospholipase D has been found on the Golgi apparatus and is regulated by ADP-ribosylation factors which are themselves regulators of vesicle trafficking. Moreover, the product of phospholipase D activity, phosphatidic acid, as well as its degradation product diacylglycerol, have been implicated in vesicle fission and fusion events. Here we summarize recent advances in the understanding of the role of phospholipase D at the Golgi apparatus.
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Affiliation(s)
- Christian Riebeling
- Department of Developmental and Molecular Biology, Albert Einstein College of Medicine of Yeshiva University, Bronx, New York 10461, USA.
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Affiliation(s)
- J H Exton
- Howard Hughes Medical Institute, Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN, USA
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Cabot MC, Zhang Z, Cao H, Lavie Y, Giuliano AE, Han TY, Jones RC. Tamoxifen activates cellular phospholipase C and D and elicits protein kinase C translocation. Int J Cancer 1997; 70:567-74. [PMID: 9052757 DOI: 10.1002/(sici)1097-0215(19970304)70:5<567::aid-ijc13>3.0.co;2-a] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The antiestrogen tamoxifen is widely used for endocrine therapy of breast cancer; however, the mechanisms of estrogen receptor-independent interactions of tamoxifen remain ill defined. Here we examine the effect of tamoxifen on the initial steps of cell signal transduction. To this end, phospholipid metabolism and protein kinase C (PKC) translocation were assessed in CCD986SK human mammary fibroblasts treated with tamoxifen. The addition of tamoxifen resulted in dose-dependent and time-dependent increases in the cellular second messengers phosphatidate (PA) and diacylglycerol (DG). On addition of ethanol to the medium, tamoxifen induced the formation of phosphatidylethanol, demonstrating that tamoxifen activates phospholipase D (PLD). Cellular DG also increased in the presence of ethanol, showing that tamoxifen also activates phospholipase C (PLC). In cells prelabeled with choline and ethanolamine, tamoxifen caused increases in choline, phosphorylcholine, ethanolamine and phosphorylethanolamine. Structure-activity relationship studies for activation of PLD revealed that tamoxifen was the most effective, whereas 4-hydroxy tamoxifen was nearly devoid of activity. Phorbol diesters also activated PLD, but estrogen had no influence. Pretreatment of cells with phorbol dibutyrate (PKC down-regulation protocol) blocked phorbol diester- and tamoxifen-induced PLD activity. Exposure of cells to the PKC inhibitor GF 109203X diminished tamoxifen-induced PLD activity. Addition of tamoxifen to cultures elicited selective membrane association of PKC epsilon. We conclude that tamoxifen exerts considerable extra-nuclear influence at the transmembrane signaling level. These events may contribute to effects beyond the scope of estrogen receptor-dependent actions.
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Affiliation(s)
- M C Cabot
- John Wayne Cancer Institute at Saint John's Hospital and Health Center, Santa Monica, CA 90404, USA
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Rabe T, Przylipiak A, Müller H, Przylipiak J, Runnebaum B. Action of vasopressin in superfused human granulosa cells in vitro. Gynecol Endocrinol 1996; 10:371-4. [PMID: 9032562 DOI: 10.3109/09513599609023599] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Arginine-vasopressin as well as luteinizing hormone (LH)/follicle-stimulating hormone (FSH) stimulate progesterone release in superfused human granulosa cells. Extracellular administration of inositol triphosphate (10(-6) mol/l) or calcium ions (10(-4) mol/l) mimics the action of both arginine-vasopressin and LH/FSH and evokes progesterone secretion in superfused granulosa cells.
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Affiliation(s)
- T Rabe
- Department of Obstetrics and Gynecology, University of Heidelberg, Germany
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Rydzewska G, Jurkowska G, Gabryelewicz A. The influence of acute ethanol ingestion on phospholipase D activity in rat pancreas. An in vitro and in vivo study. INTERNATIONAL JOURNAL OF PANCREATOLOGY : OFFICIAL JOURNAL OF THE INTERNATIONAL ASSOCIATION OF PANCREATOLOGY 1996; 20:59-68. [PMID: 8872525 DOI: 10.1007/bf02787377] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
CONCLUSION Since phosphatidic acid (PA), a product of phospholipase D(PLD), is known as a second messenger probably involved in cell proliferation and differentiation, our results potentially suggest a new mechanism for pancreatic tissue injury after ethanol ingestion. BACKGROUND The mechanisms by which ethanol causes pancreatic injury are still not clear. In vitro studies have suggested a relationship of PLD to ethanol metabolism. This study was undertaken to establish the involvement of PLD in ethanol metabolism in isolated pancreatic acini and to determine the influence of acute ethanol ingestion on PLD activity in pancreas and pancreatic growth after cerulein (Ce) infusion. METHODS Dispersed pancreatic acini prelabeled with 3H myristic acid were incubated with 500 pM Ce in the presence of different concentrations of ethanol; then labeled PA and phosphatidylethanol (PEt) production were measured under the same experimental conditions. For in vivo study, male rats were infused with Ce (0.25 microgram/kg/h) or saline; 1 h before infusion, animals were treated with 40% ethanol (5 g/kg p.o.) or saline, respectively. After 1, 2, and 48 h of Ce infusion, rats were killed; dispersed pancreatic acini were then prepared and PLD activity was measured. Pancreatic weight, protein, RNA, and DNA content were also established. RESULTS The production of PEt in vitro after Ce stimulation was significantly elevated with 1% ethanol in the medium. In the presence of different concentrations of ethanol (0.5-2%), a significant inhibition of PA accumulation in in vitro experiments was observed. The decrease of PA accumulation with ethanol was parallel to the increase of PEt production under the same experimental conditions. PLD activity was significantly elevated after 1 and 2 h of Ce infusion (116 and 105%, respectively), reaching control value after 48 h. Acute ethanol ingestion significantly diminished PLD activity after 1 and 2 h. After 48 h of Ce infusion, a significant increase in pancreatic weight, protein, RNA, and DNA content in pancreatic tissue was found. Ethanol was not able to influence pancreatic weight, proteins and RNA content. However, it had the potency to diminish DNA content after 48 h of Ce infusion.
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Affiliation(s)
- G Rydzewska
- Gastroenterology Department, University Medical School, Bialystok, Poland
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Abstract
There is increased interest in physiological functions and mechanisms of action of sphingolipids metabolites, ceramide, sphingosine, and sphingosine-1-phosphate (SPP), members of a new class of lipid second messengers. This review summarizes current knowledge regarding the role of these sphingolipids metabolites in the actions of growth factors and focuses on the second messenger roles of sphingosine and its metabolite, SPP, in the regulation of cell growth. We also discuss possible interactions with intermediates of the well known glycerophospholipid cycle. Sphingosine and SPP generally provide positive mitogenic signals whereas ceramide has been reported to induce apoptosis and cell arrest in several mammalian cell lines. Stimulation of phospholipase D leading to an increase in phosphatidic acid, a positive regulator of cell growth, by sphingosine and SPP, and its inhibition by ceramide, might be related to their opposite effects on cell growth. This also indicates that sphingolipid turnover could regulate the diacylglycerol cycle. Cross-talk between sphingolipid turnover pathways and the diacylglycerol cycle increases complexity of signaling pathways leading to cellular proliferation and adds additional sites of regulation.
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Affiliation(s)
- S Spiegel
- Department of Biochemistry and Molecular Biology, Georgetown University Medical Center, Washington, DC 20007, USA
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Abstract
Phospholipase D activity is stimulated rapidly upon occupation of cell-surface receptors. One of the intracellular regulators of phospholipase D activity has been identified as ADP ribosylation factor (ARF). ARF is a small GTP binding protein whose function has been elucidated in vesicular traffic. This review puts into context the connection between the two fields of signal transduction and vesicular transport.
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Affiliation(s)
- S Cockcroft
- Department of Physiology, University College London, UK.
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Abstract
In nearly all mammalian cells and tissues examined, protein kinase C (PKC) has been shown to serve as a major regulator of a phosphatidylcholine-specific phospholipase D (PLD) activity. At least 12 distinct isoforms of PKC have been described so far; of these enzymes only the alpha- and beta-isoforms were found to regulate PLD activity. While the mechanism of this regulation has remained unknown, available evidence suggests that both phosphorylating and non-phosphorylating mechanisms may be involved. A phosphatidylcholine-specific PLD activity was recently purified from pig lung, but its possible regulation by PKC has not been reported yet. Several cell types and tissues appear to express additional forms of PLD which can hydrolyze either phosphatidylethanolamine or phosphatidylinositol. It has also been reported that at least one form of PLD can be activated by oncogenes, but not by PKC activators. Similar to activated PKC, some of the primary and secondary products of PLD-mediated phospholipid hydrolysis, including phosphatidic acid, 1,2-diacylglycerol, choline phosphate and ethanolamine, also exhibit mitogenic/co-mitogenic effects in cultured cells. Furthermore, both the PLD and PKC systems have been implicated in the regulation of vesicle transport and exocytosis. Recently the PLD enzyme has been cloned and the tools of molecular biology to study its biological roles will soon be available. Using specific inhibitors of growth regulating signals and vesicle transport, so far no convincing evidence has been reported to support the role of PLD in the mediation of any of the above cellular effects of activated PKC.
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Affiliation(s)
- Z Kiss
- Hormel Institute, University of Minnesota, Austin 55912, USA
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11
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Wieder T, Zhang Z, Geilen CC, Orfanos CE, Giuliano AE, Cabot MC. The antitumor phospholipid analog, hexadecylphosphocholine, activates cellular phospholipase D. Cancer Lett 1996; 100:71-9. [PMID: 8620456 DOI: 10.1016/0304-3835(95)04072-2] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Hexadecylphosphocholine (HePC), a glycerol-free phospholipid analog, belongs to a new class of drugs that demonstrate selective anticancer activity. The mechanisms underlying the anticancer activity are unclear. To investigate possible signal transduction relationships we examined the influence of HePC on cellular phospholipid metabolism. When HePC was added to cultured human breast fibroblasts (CCD-986-SK cells) that had been radiolabeled with fatty acid, phosphatidylethanol (PEt, the transphosphatidylation product of phospholipase D (PLD)) formation was stimulated as early as 5 min after addition. In cells labeled with [3H]choline, HePC treatment caused release of choline-containing metabolites to the culture medium, concurrent with PEt formation. HePC also elicited formation of diacylglycerol (DG) which, after 30 min increased 3.5-fold over control. As little is known regarding HePC and PLD, attention was directed towards studies on PC metabolism by PLD. PEt formation was shown to be optimal at 20-50 microM HePC, and structure-activity studies showed HePC to be more potent than either lyso-phosphatidylcholine or 1-hexadecyl-2-O-methyl-rac-glycero-3-phosphocholine for PLD activation. PLD activity induced by HePC was totally inhibited by cellular pretreatment with phorbol dibutyrate, and 59% diminished by pretreatment of cells with staurosporine, a protein kinase C (PKC) inhibitor. Our results demonstrate for the first time that HePC activates PLD, and suggest that PKC participates in this response. The relationship of PLD to the anticancer properties of HePC may be clinically relevant to drug actions.
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Affiliation(s)
- T Wieder
- Department of Dermatology, University Medical Center Benjamin Franklin, Free University of Berlin, Germany
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12
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Richard A, Bourgoin S, Naccache PH, L'Heureux GP, Krump E, McColl SR, Pelletier G. C2-ceramide primes specifically for the superoxide anion production induced by N-formylmethionylleucyl phenylalanine (fMLP) in human neutrophils. BIOCHIMICA ET BIOPHYSICA ACTA 1996; 1299:259-66. [PMID: 8555272 DOI: 10.1016/0005-2760(95)00215-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Activated sphingomyelinases release ceramide molecules believed to be involved in intracellular signalling. The present study investigated whether soluble C2-ceramide modulates some of the effects of N-formylmethionylleucyl phenylalanine (fMLP) and other agonists on human neutrophils (or polymorphonuclear leukocytes-PMN); principally superoxide anion (O2-) production. The preincubation of PMN for 15 min with C2-ceramide increased by up to almost 3-fold the amounts of O2- generated in response to 0.1 and 1 microM fMLP. Priming was detected at C2-ceramide concentrations of 2 microM to 4 microM per million PMN. Though less potent than C2-ceramide, C6-ceramide (N-hexanoylsphingosine) could prime for O2- generated in response to 0.1 microM fMLP, with maximal effects obtained at 10-20 microM. In contrast, micromolar concentrations of sphingosine, dihydroceramide, and ceramide-phosphate, failed to exert any potentiating effect on fMLP-induced O2- generation. As expected, TNF-alpha (1000 U/ml), also primed for fMLP-induced O2- production; however, the combination of TNF-alpha and C2-ceramide showed no additive effect. Moreover, S. aureus sphingomyelinase (0.1 U/ml), was unable to reproduce the priming effects of C2-ceramide and TNF-alpha. C2-ceramide at 2 microM did not enhance the production of O2- induced by 100 nM recombinant human interleukin-8 (IL-8), leukotriene B4 (LTB4), platelet-activating factor (PAF) or 20 mM sodium fluoride (NaF). Furthermore, C2-ceramide (2 microM) did not enhance the mobilization of calcium, the release of arachidonic acid or the accumulation of phosphatidylethanol, induced by 100 nM fMLP. This suggests that probably neither phospholipases C, A2 or D (PLC, PLA2, PLD) were involved in the priming effect by C2-ceramide. However, C2-ceramide inhibited in a dose-related manner the production of O2- induced by phorbol 12-myristate 13-acetate (PMA) and mezerein. Furthermore, PMA-stimulated PLD activity was also significantly reduced by a preincubation of PMN with C2-ceramide. The priming of O2- production by C2-ceramide could involve yet unidentified mechanisms specific for fMLP, or it might imply that cytokines such as TNF-alpha have different mechanisms than C2-ceramide.
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Affiliation(s)
- A Richard
- Centre de Recherche en Rhumatologie et Immunologie, Faculté de Médecine, Université Laval, Ste-Foy, Québec, Canada
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Affiliation(s)
- J P Liu
- Department of Medical Oncology, Newcastle Mater Misericordiae Hospital, New South Wales, Australia
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Walsh JP, Suen R, Glomset JA. Arachidonoyl-diacylglycerol kinase. Specific in vitro inhibition by polyphosphoinositides suggests a mechanism for regulation of phosphatidylinositol biosynthesis. J Biol Chem 1995; 270:28647-53. [PMID: 7499383 DOI: 10.1074/jbc.270.48.28647] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
We previously described the purification of a membrane-bound diacylglycerol kinase highly selective for sn-1-acyl-2-arachidonoyl diacylglycerols (Walsh, J. P., Suen, R., Lemaitre, R. N., and Glomset, J. A. (1994) J. Biol. Chem. 269, 21155-21164). This enzyme appears to be responsible for the rapid clearance of the arachidonate-rich pool of diacylglycerols generated during stimulus-induced phosphoinositide turnover. We have now shown phosphatidylinositol 4,5-bisphosphate to be a potent and specific inhibitor of arachidonoyl-diacylglycerol kinase. Kinetic analyses indicated a Ki for phosphatidylinositol 4,5-bisphosphate of 0.04 mol %. Phosphatidic acid also was an inhibitor with a Ki of 0.7 mol %. Other phospholipids had only small effects at these concentrations. A series of multiply phosphorylated lipid analogs also inhibited the enzyme, indicating that the head group phosphomonoesters are the primary determinants of the polyphosphoinositide effect. However, these compounds were not as potent as phosphatidylinositol 4,5-bisphosphate, indicating some specificity for the polyphosphoinositide additional to its total charge. Five other diacylglycerol kinases were activated to varying degrees by phosphatidylinositol 4,5-bisphosphate and phosphatidic acid, suggesting that inhibition by acidic lipids may be specific for the arachidonoyl-DAG kinase isoform. Given the presumed role of arachidonoyl-diacylglycerol kinase in the phosphoinositide cycle, this inhibition may represent a mechanism for polyphosphoinositides to regulate their own synthesis.
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Affiliation(s)
- J P Walsh
- Department of Medicine, Indiana University, Indianapolis 46202-5111, USA
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Gómez-Muñoz A, Waggoner DW, O'Brien L, Brindley DN. Interaction of ceramides, sphingosine, and sphingosine 1-phosphate in regulating DNA synthesis and phospholipase D activity. J Biol Chem 1995; 270:26318-25. [PMID: 7592842 DOI: 10.1074/jbc.270.44.26318] [Citation(s) in RCA: 128] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
C2- and C6-ceramides (N-acetylsphingosine and N-hexanoylsphingosine, respectively) abolished the stimulation of DNA synthesis by sphingosine 1-phosphate in rat fibroblasts. This inhibition by ceramide was partially prevented by insulin. C2-ceramide did not alter the stimulation of DNA synthesis by insulin and decreased the sphingosine-induced stimulation by only 16%. The ceramides did not significantly modify the actions of sphingosine or sphingosine 1-phosphate in decreasing cAMP concentrations. C2- and C6-ceramides blocked the activation of phospholipase D by sphingosine 1-phosphate, and this inhibition was not affected by insulin. Okadaic acid decreased the activation of phospholipase D by sphingosine 1-phosphate and did not reverse the inhibitory effect of C2-ceramide on this activation. Therefore, this effect of C2-ceramide is unlikely to involve the stimulation of phosphoprotein phosphatase activity. Sphingosine did not activate phospholipase D activity significantly after 10 min. C2-ceramide stimulated the conversion of exogenous [3H]sphingosine 1-phosphate to sphingosine and ceramide in fibroblasts. Ceramides can inhibit some effects of sphingosine 1-phosphate by stimulating its degradation via a phosphohydrolase that also hydrolyzes phosphatidate. Furthermore, C2- and C6-ceramides stimulated ceramide production from endogenous lipids, and this could propagate the intracellular signal. This work demonstrates that controlling the production of ceramide versus sphingosine and sphingosine 1-phosphate after sphingomyelinase activation could have profound effects on signal transduction.
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Affiliation(s)
- A Gómez-Muñoz
- Department of Biochemistry, University of Alberta, Edmonton, Canada
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16
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Tran K, Zha X, Chan M, Choy PC. Enhancement of phospholipid hydrolysis in vasopressin-stimulated BHK-21 and H9c2 cells. Mol Cell Biochem 1995; 151:69-76. [PMID: 8584016 DOI: 10.1007/bf01076898] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The hydrolysis of phospholipids in vasopressin-stimulated baby hamster kidney (BHK)-21 and H9c2 myoblastic cells was investigated. Phosphatidylcholine and phosphatidylethanolamine in these cells were pulse labelled with [3H]glycerol, [3H]myristate, [3H]choline or [3H]ethanolamine, and chased with the non-labelled precursor until linear turnover rates were obtained. When cells labelled with [3H]glycerol or [3H]myristate were stimulated by vasopressin, no significant decrease in the labelling of phosphatidylcholine was detected, but the labelling of phosphatidic acid was elevated. However, the labellings of phosphatidylethanolamine and its hydrolytic product were not affected by vasopressin stimulation. When the cells were pulse labelled with [3H]-choline, vasopressin stimulation caused a decrease in the labelled phosphatidylcholine with a corresponding increase in the labelled choline. The apparent discrepancy between the two types of labelling might be explained by the recycling of labelled phosphatidic acid back into phosphatidylcholine, thus masking the reduction in the labelled phospholipid during vasopressin stimulation. Alternatively, the labelled choline produced by vasopressin stimulation was released into the medium, thus reducing the recycling of label precursor back into the phospholipid and making the decrease in the labelling of phosphatidylcholine readily detectable. Further studies revealed that vasopressin treatment caused an enhancement of phospholipase D activity in these cells. The presence of substrate-specific phospholipase D isoforms in mammalian tissues led us to postulate that the differential stimulation of phospholipid hydrolysis by vasopressin was caused by the enhancement of a phosphatidylcholine-specific phospholipase D in both BHK-21 and the H9c2 cells.
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Affiliation(s)
- K Tran
- Department of Biochemistry and Molecular Biology, University of Manitoba, Winnipeg, Canada
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Effect of Vasoconstrictor Agents on Diacylglycerol Content of Normal and Vasospastic Canine Basilar Arteries In Vitro. Neurosurgery 1995. [DOI: 10.1097/00006123-199504000-00021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
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Yamakawa K, Peterson JW, Sibilia R, Zervas NT. Effect of vasoconstrictor agents on diacylglycerol content of normal and vasospastic canine basilar arteries in vitro. Neurosurgery 1995; 36:789-96. [PMID: 7596511 DOI: 10.1227/00006123-199504000-00021] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
A causal or supportive relationship between 1,2-diacylglycerol (DAG) content and the maintenance of tonic vasoconstriction was sought in canine basilar arteries treated in vitro with various agents reported to increase DAG levels in other tissues (platelet-derived growth factor, vasopressin, angiotensin II, and endothelin-1) and, conversely, with agents known to activate sustained constriction (high K+, phorbol ester, hemolysate, and endothelin-1). Multiple segments from individual isolated arteries were prepared. Some segments were immediately frozen as controls and others incubated in physiological saline solution at 37 degrees C for either 5 minutes or 30 minutes in the presence or absence of different concentrations of the test materials. Segments were then quickly frozen until homogenized for lipid extraction and DAG assay. The DAG content of samples incubated up to 2 hours in physiological saline solution alone did not significantly differ from that of immediately frozen control samples. Resting DAG content expressed relative to total protein measured in each sample averaged 3.82 +/- 0.26 (standard error of the mean) pmol DAG/microgram of protein (74 samples from 37 arteries). Endothelin at 2 x 10(-7) mol/L led to a statistically significant increase in DAG content of approximately 40% of basal content at 5 and 30 minutes. A smaller increase in DAG attributable to hemolysate (approximately 25%) was statistically significant at 30 minutes, whereas vasopressin provoked a notable decrease in DAG content. The other agents had no effect. No differences in these results were noted between normal canine basilar arteries and arteries constricted in vivo by subarachnoid blood clot before isolation.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- K Yamakawa
- Neurosurgical Service, Massachusetts General Hospital, Boston, USA
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19
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Cabot MC, Zhang ZC, Giuliano AE. Tamoxifen elicits rapid transmembrane lipid signal responses in human breast cancer cells. Breast Cancer Res Treat 1995; 36:299-306. [PMID: 8573712 DOI: 10.1007/bf00713401] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The antiestrogen tamoxifen competes with estrogen for receptor occupancy, although reports indicate that not all effects of tamoxifen are mediated via this specific interaction. In the present study we sought to determine whether tamoxifen can initiate transmembrane lipid signals. Lipid signaling is a prominent mode by which hormones, growth factors, and phorbol diesters transduce messages. Using the human mammary carcinoma cell line MDA-MB-231, phospholipid metabolism was analyzed in cells prelabeled with 3H-fatty acid. After short-term (10 min) exposure to tamoxifen (10 microM), cellular phosphatidic acid (PA) increased by approximately 50%. Dose-response kinetics for PA formation were obtained over a tamoxifen range of 2.5-20 microM. Treatment of MDA-MB-231 cells with phorbol diester (12-O-tetradecanoylphorbol-13-acetate, TPA) also elicited PA generation (60% above control). Interestingly, addition of tamoxifen, a purported protein kinase C inhibitor, to TPA-treated cells, caused further increase in PA (approximately 100% above control). PA, a second messenger lipid produced upon effector-receptor coupling, shares a prominent role in signal transduction events that govern cellular proliferation. It is therefore suggested that some actions of tamoxifen are mediated by promoting production of second messenger lipids that elicit transmembrane signal transduction cascades. This view is in line with ideas on non-estrogen receptor associated actions of tamoxifen by way of alternate binding sites.
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Affiliation(s)
- M C Cabot
- John Wayne Cancer Institute, Saint John's Hospital and Health Center, Santa Monica, CA 90404, USA
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Liu JP, Engler D, Funder JW, Robinson PJ. Arginine vasopressin (AVP) causes the reversible phosphorylation of the myristoylated alanine-rich C kinase substrate (MARCKS) protein in the ovine anterior pituitary: evidence that MARCKS phosphorylation is associated with adrenocorticotropin (ACTH) secretion. Mol Cell Endocrinol 1994; 105:217-26. [PMID: 7859929 DOI: 10.1016/0303-7207(94)90173-2] [Citation(s) in RCA: 26] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
We have recently shown that AVP causes a protein kinase C (PKC)-dependent increase in ACTH release and biosynthesis in ovine anterior pituitary cells. In these cells, AVP also causes the translocation of PKC from the cytosol to the cell membrane which is maximal at 5 min, but the intracellular events distal to protein kinase C activation that underlie ACTH secretion have not been well characterized to date. Since the MARCKS protein has been implicated in neurosecretion and is phosphorylated by PKC in synaptosomes, studies were carried out to determine whether AVP might cause MARCKS phosphorylation in the ovine anterior pituitary, and to determine whether this phenomenon might be temporally correlated with PKC translocation and the release of ACTH. When cytosolic fractions of rat brain, ovine anterior pituitary, and cultured ovine anterior pituitary cells were incubated with purified PKC, several proteins were phosphorylated including those in the region of 83-85 kDa. After precipitation of the proteins with 40% acetic acid, the 83-85 kDa phosphoproteins were selectively recovered in the acid soluble phase. Phosphopeptide maps of either the 83 or 85 kDa proteins were generated with Staphylococcus aureus V8 protease and revealed 13 and 9 kDa phosphopeptides, which are characteristic of the authentic MARCKS protein. An identical phosphopeptide map was also obtained when the MARCKS protein was selectively extracted from intact 32P-labeled anterior pituitary cells. MARCKS phosphorylation was markedly increased when ovine anterior pituitary cells were exposed to 1 microM phorbol 12-myristate 13-acetate (PMA). When the cells were exposed to 1 microM AVP, MARCKS phosphorylation increased at 15 s and reached the maximal plateau value at 30 s. MARCKS phosphorylation then started to diminish at 2 min, and baseline levels were attained by 10 min. In the same cells, AVP stimulated ACTH release in a biphasic manner-during the first 30 s, there resulted a rapid burst of ACTH secretion that was followed by a slower, but sustained rate of secretion. We conclude that: (1) AVP causes a rapid, and reversible, phosphorylation of the MARCKS protein in the ovine anterior pituitary; (2) since the AVP-induced increase in MARCKS phosphorylation occurs much earlier in these cells than does PKC trans-location, MARCKS phosphorylation may provide a more sensitive index of the onset of PKC activation than the translocation assay; (3) the close temporal association between MARCKS phosphorylation and the rapid early release of ACTH suggests that MARCKS phosphorylation may be involved in the initial intracellular events that underly exocytosis of the hormone.
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Affiliation(s)
- J P Liu
- Prince Henry's Institute of Medical Research, Clayton, Victoria, Australia
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21
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Schmidt M, Hüwe SM, Fasselt B, Homann D, Rümenapp U, Sandmann J, Jakobs KH. Mechanisms of phospholipase D stimulation by m3 muscarinic acetylcholine receptors. Evidence for involvement of tyrosine phosphorylation. EUROPEAN JOURNAL OF BIOCHEMISTRY 1994; 225:667-75. [PMID: 7957182 DOI: 10.1111/j.1432-1033.1994.00667.x] [Citation(s) in RCA: 78] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
In human embryonic kidney cells stably expressing the human m3 muscarinic acetylcholine receptor (mAChR) subtype, agonist (carbachol) activation stimulated phospholipase C, increased cytoplasmic calcium concentration, induced tyrosine phosphorylation of various cellular proteins and activated phospholipase D. Bypassing membrane receptors, phospholipase D was activated in these cells by direct activation of protein kinase C by phorbol esters, by direct activation of GTP-binding proteins by A1F4- and a stable GTP analogue (in permeabilized cells), by increasing cytoplasmic calcium concentration with the calcium ionophore A23187 and also apparently by tyrosine phosphorylation. In order to identify possible mechanisms by which the m3 mAChR couples to phospholipase D, various inhibitors of protein kinase C, tyrosine kinases and calcium-dependent events were studied. Prevention of an agonist-induced increase in cytoplasmic calcium concentration did not alter the mAChR-induced phospholipase D stimulation. The protein kinase C inhibitors, calphostin C and staurosporine, efficiently prevented phospholipase D activation by phorbol 12-myristate 13-acetate but only partially inhibited the activation induced by the mAChR agonist. Additionally, down-regulation of protein kinase C by prolonged exposure to phorbol 12-myristate 13-acetate abrogated phospholipase D activation by this effector but had only minor or no effects on the response to the mAChR agonist and direct activators of GTP-binding proteins. In contrast, the tyrosine kinase inhibitor genistein abolished the carbachol-induced and A1F4(-)-induced phospholipase D activation but had no effect on enzyme activation by phorbol 12-myristate 13-acetate. The data indicate that phospholipase D in m3 mAChR-expressing human embryonic kidney cells can be activated by various different mechanisms, i.e. receptor agonists, GTP-binding proteins, protein kinase C-dependent and calcium-dependent events and tyrosine phosphorylation. The coupling of m3 mAChR to phospholipase D appears to be largely independent of concomitant phospholipase C activation with subsequent increase in cytoplasmic calcium concentration and protein kinase C activity. The data instead suggest the involvement of an essential protein tyrosine phosphorylation mechanism in phopsholipase D activation by the m3 mAChR and heterotrimeric GTP-binding proteins.
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Affiliation(s)
- M Schmidt
- Institut für Pharmakologie, Universität GH Essen, Germany
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22
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Liu JP, Engler D, Funder JW, Robinson PJ. Arginine vasopressin (AVP) causes the reversible phosphorylation of the myristoylated alanine-rich C kinase substrate (MARCKS) protein in the ovine anterior pituitary: evidence that MARCKS phosphorylation is associated with adrenocorticotropin (ACTH) secretion. Mol Cell Endocrinol 1994; 101:247-56. [PMID: 9397959 DOI: 10.1016/0303-7207(94)90241-0] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
We have recently shown that AVP causes a protein kinase C (PKC)-dependent increase in ACTH release and biosynthesis in ovine anterior pituitary cells. In these cells, AVP also causes the translocation of PKC from the cytosol to the cell membrane which is maximal at 5 min, but the intracellular events distal to protein kinase C activation that underlie ACTH secretion have not been well characterized to date. Since the MARCKS protein has been implicated in neurosecretion and is phosphorylated by PKC in synaptosomes, studies were carried out to determine whether AVP might cause MARCKS phosphorylation in the ovine anterior pituitary, and to determine whether this phenomenon might be temporally correlated with PKC translocation and the release of ACTH. When cytosolic fractions of rat brain, ovine anterior pituitary, and cultured ovine anterior pituitary cells were incubated with purified PKC, several proteins were phosphorylated including those in the region of 83-85 kDa. After precipitation of the proteins with 40% acetic acid, the 83-85 kDa phosphoproteins were selectively recovered in the acid soluble phase. Phosphopeptide maps of either the 83 or 85 kDa proteins were generated with Staphylococcus aureus V8 protease and revealed 13 and 9 kDa phosphopeptides, which are characteristic of the authentic MARCKS protein. An identical phosphopeptide map was also obtained when the MARCKS protein was selectively extracted from intact 32P-labeled anterior pituitary cells. MARCKS phosphorylation was markedly increased when ovine anterior pituitary cells were exposed to 1 microM phorbol 12-myristate 13-acetate (PMA). When the cells were exposed to 1 microM AVP, MARCKS phosphorylation increased at 15 s and reached the maximal plateau value at 30 s. MARCKS phosphorylation then started to diminish at 2 min, and baseline levels were attained by 10 min. In the same cells, AVP stimulated ACTH release in a biphasic manner - during the first 30 s, there resulted a rapid burst of ACTH secretion that was followed by a slower, but sustained rate of secretion. We conclude that: (1) AVP causes a rapid, and reversible, phosphorylation of the MARCKS protein in the ovine anterior pituitary; (2) since the AVP-induced increase in MARCKS phosphorylation occurs much earlier in these cells than does PKC trans-location, MARCKS phosphorylation may provide a more sensitive index of the onset of PKC activation than the translocation assay; (3) the close temporal association between MARCKS phosphorylation and the rapid early release of ACTH suggests that MARCKS phosphorylation may be involved in the initial intracellular events that underly exocytosis of the hormone.
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Affiliation(s)
- J P Liu
- Prince Henry's Institute of Medical Research, Clayton, Victoria, Australia
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23
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Cell-permeable ceramides inhibit the stimulation of DNA synthesis and phospholipase D activity by phosphatidate and lysophosphatidate in rat fibroblasts. J Biol Chem 1994. [DOI: 10.1016/s0021-9258(17)37058-8] [Citation(s) in RCA: 148] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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24
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Gustavsson L, Moehren G, Torres-Marquez M, Benistant C, Rubin R, Hoek J. The role of cytosolic Ca2+, protein kinase C, and protein kinase A in hormonal stimulation of phospholipase D in rat hepatocytes. J Biol Chem 1994. [DOI: 10.1016/s0021-9258(17)42190-9] [Citation(s) in RCA: 49] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
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25
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Martin A, Gomez-Muñoz A, Waggoner D, Stone J, Brindley D. Decreased activities of phosphatidate phosphohydrolase and phospholipase D in ras and tyrosine kinase (fps) transformed fibroblasts. J Biol Chem 1993. [DOI: 10.1016/s0021-9258(20)80473-6] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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26
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Kester M. Platelet-activating factor stimulates phosphatidic acid formation in cultured rat mesangial cells: roles of phospholipase D, diglyceride kinase, and de novo phospholipid synthesis. J Cell Physiol 1993; 156:317-25. [PMID: 8393878 DOI: 10.1002/jcp.1041560214] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Platelet-activating factor (PAF) stimulates phospholipase C (PLC)-induced hydrolysis of phosphatidylinositol-4,5-bisphosphate (PtdIns-4,5-P2). Yet, PAF-stimulated diglycerides (DG) are still elevated at time points where inositol polyphosphates have returned to basal levels. Thus, other signal transduction pathways that hydrolyze phosphatidylcholine (PtdCho) or phosphatidylethanolamine (PtdEth) and form DG and phosphatidic acids (PA) through either PLC or phospholipase D (PLD) may also mediate PAF-stimulated cellular responses. Initially the effects of PAF upon 32P-PA generation in mesangial cells (MC) were assessed. PA formation may be indicative of several metabolic pathways including PLD and DG kinase activities as well as de novo phospholipid synthesis. PAF (10(-7) M) increased 32P-PA formation as early as 5 seconds and this elevation persisted up to 15 minutes. When MC were pretreated with the DG kinase inhibitor-R59022, PAF-induced 32P-PA formation was diminished at early but not late time points, demonstrating that the initial component of PA formation may be due, in part, to PLC activation and subsequent phosphorylation of DG. The reciprocal reaction, PA phosphohydrolase, which dephosphorylates PA to from DG was not stimulated by PAF, suggesting that the sustained elevation of DG induced by PAF is primarily a reflection of PLC. 3H-glycerol pulse-labeling experiments suggest that PAF also stimulates de novo phospholipid synthesis which also contributes to PA formation. Conclusive proof for PLD in the generation of PA was obtained by assessing the formation of 3H-phosphatidyl-ethanol (PEt) from 3H-alkyl-lyso-glycero phosphocholine (GPC) and exogenous ethanol. PAF stimulated alkyl-PEt generation in the presence but not the absence of 0.5% ethanol. Also, PAF induced a concomitant elevation of alkyl-PA at 15 minutes and this elevation of alkyl-PA was reduced when the cells were exposed to exogenous ethanol, reflecting the formation of PEt. Corroborating evidence suggests that PAF stimulates 3H-choline and 3H-ethanolamine release, suggesting that PtdCho and PtdEth are substrates for PLD. Thus, these data demonstrate that MC respond to PAF with elevated PLD and DG kinase activities as well as with an increased rate of de novo lipid synthesis which increases PA, a potential intracellular signal.
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Affiliation(s)
- M Kester
- Department of Medicine, Case Western Reserve University School of Medicine, Cleveland, Ohio
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27
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Ben-Av P, Eli Y, Schmidt US, Tobias KE, Liscovitch M. Distinct mechanisms of phospholipase D activation and attenuation utilized by different mitogens in NIH-3T3 fibroblasts. EUROPEAN JOURNAL OF BIOCHEMISTRY 1993; 215:455-63. [PMID: 8344313 DOI: 10.1111/j.1432-1033.1993.tb18054.x] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
The activation of phospholipase D (PLD) by platelet-derived growth factor (PDGF), prostaglandin F2 alpha and 12-O-tetradecanoylphorbol 13-acetate (TPA) was studied in NIH-3T3 fibroblasts. PLD activation was determined by measuring the production of both [3H]phosphatidic acid and [3H]phosphatidylpropanol (products of the PLD-catalyzed hydrolysis and transphosphatidylation reactions, respectively), in cells that were metabolically pre-labeled with [3H]oleic acid. All mitogens caused a rapid (within 2 min) activation of PLD. Activation of PLD by prostaglandin F2 alpha and PDGF was transient and declined to near basal levels by 15 min and 55 min, respectively. In contrast, TPA-induced activation of PLD was sustained for at least 60 min of incubation. A combination of maximally effective concentrations of PDGF and TPA stimulated PLD activity in a non-additive manner, while the effect of prostaglandin F2 alpha was additional to that of either PDGF or TPA. The protein kinase inhibitor staurosporine inhibited PLD activation by PDGF or TPA with almost identical dose/response curves. In contrast, staurosporine potentiated prostaglandin-F2 alpha-induced PLD activation. The specific protein kinase C inhibitor GF109203X (a bisindolylmaleimide) inhibited PLD activation by prostaglandin F2 alpha and PDGF at concentrations higher than those required for inhibition of PLD activation induced by TPA. Depletion of cellular protein kinase C abolished PLD activation by all three mitogens without affecting in vitro activity of membrane-bound PLD. The distinct kinetics of PLD activation and its differential susceptibility to protein kinase inhibitors suggest the existence of agonist-specific activation and/or inactivation mechanisms. The results indicate also that protein kinase C participates in the mechanism of PLD activation via PDGF, while the effect of prostaglandin F2 alpha involves a pathway independent of protein kinase C.
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Affiliation(s)
- P Ben-Av
- Department of Hormone Research, Weizmann Institute of Science, Rehovot, Israel
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28
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Bütikofer P, Yee MC, Schott MA, Lubin BH, Kuypers FA. Generation of phosphatidic acid during calcium-loading of human erythrocytes. Evidence for a phosphatidylcholine-hydrolyzing phospholipase D. EUROPEAN JOURNAL OF BIOCHEMISTRY 1993; 213:367-75. [PMID: 8386626 DOI: 10.1111/j.1432-1033.1993.tb17770.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
We have studied the mechanism by which calcium-loading of human erythrocytes stimulates phospholipid turnover and generates diacylglycerol and phosphatidic acid. Using quantitative measurement of individual phospholipid classes, we have demonstrated that the amount of phosphatidic acid generated during calcium-loading of intact red cells exceeds the amount of diacylglycerol formed by phospholipase-C-mediated hydrolysis of the polyphosphoinositol lipids and that addition of the diacylglycerol kinase inhibitor, R59022, only partly inhibited this increase. Thus, in contrast to current explanations, the phosphatidic acid generated following calcium-loading of erythrocytes cannot be solely explained by the action of a polyphosphoinositol-lipid-specific phospholipase C with subsequent phosphorylation of diacylglycerol to phosphatidic acid. Our data demonstrate that calcium-loading of intact erythrocytes, but not of red cell ghost membranes, causes a small but significant decrease in the relative amount of phosphatidylcholine (PtdCho). In order to identify the mechanisms responsible for calcium-mediated hydrolysis of PtdCho, we encapsulated Ptd[Me-14C]Cho-containing rat liver microsomes into erythrocytes and studied the generation of [Me-14C]choline and phospho[Me-14C]choline. We found that choline was the only detectable 14C-labeled product. Furthermore, incubation of erythrocytes with calcium under hypotonic conditions and in the presence of [14C]PtdCho vesicles and ethanol resulted in the formation of [14C]phosphatidylethanol. Together, these results suggest that the loss of PtdCho during calcium-loading of human erythrocytes is caused by a previously unrecognized PtdCho-hydrolyzing phospholipase D, resulting in direct generation of phosphatidic acid. Analysis of the molecular species composition of PtdCho, phosphatidic acid, and diradylglycerol, confirm the simultaneous actions of PtdCho-hydrolyzing and polyphosphoinositol-lipid-hydrolyzing phospholipases in calcium-loaded human erythrocytes.
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Affiliation(s)
- P Bütikofer
- Children's Hospital Oakland Research Institute, CA
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29
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Huang C, Wykle RL, Cabot MC. Comparison of phospholipase D activity in vasopressin- and phorbol ester-stimulated fibroblasts. FEBS Lett 1993; 319:141-4. [PMID: 8454047 DOI: 10.1016/0014-5793(93)80054-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Phospholipase D (PLD) activation by vasopressin (VP) was compared to activation by TPA in REF52 cells prelabeled with [3H]glycerol and [14C]myristic acid. Upon VP-treatment, the formation of [3H] and [14C]phosphatidic acid (PA) and phosphatidylethanol (PEt) was accompanied by the loss of radioactivity from PC and PI. However, upon TPA-treatment, radioactivity was lost from PC only. No significant changes of phosphatidylethanolamine and phosphatidylserine were detected in the same samples. The inclusion of 5 microM staurosporine for 10 min diminished the production of [3H]PEt and [14C]PEt by 27% and 53% in VP-treated cells, and by 100% and 75% in TPA-treated cells, respectively. Adding 1 mM EGTA to chelate extracellular Ca2+ inhibited [3H]PEt by approximately 31% and [14C]PEt by 17% after VP-stimulation. In contrast, EGTA had no effect on TPA-stimulation. The data suggest that REF52 cells contain dual PLD activities. The first is stimulated only by VP, requires Ca2+ and hydrolyzes PI. The second is stimulated by both TPA and VP, activated by protein kinase C and hydrolyzes PC.
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Affiliation(s)
- C Huang
- Department of Biochemistry, Bowman Gray School of Medicine, Wake Forest University, Winston-Salem, NC 27157-1016
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30
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Thompson NT, Garland LG, Bonser RW. Phospholipase D: regulation and functional significance. ADVANCES IN PHARMACOLOGY (SAN DIEGO, CALIF.) 1993; 24:199-238. [PMID: 8389186 DOI: 10.1016/s1054-3589(08)60938-2] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
PLD is a major route for hydrolysis of PC in most tissues, consistent with it playing an important role in signal transduction. The enzyme appears to be activated by a variety of different mechanisms in different tissues, suggesting there might be several different isoforms. Little, however, is known at present about its enzymology and molecular biology. There is little direct evidence to indicate the functional significance of PLD activation but an accumulation of indirect evidence links PLD with prolonged changes in cell function. In particular, two areas where there is strong evidence for a role for PLD are mitogenesis and leukocyte hyperresponsiveness. An important area for future work will be the investigation of how products from the PLD pathway exert these effects. Current evidence suggests an important role for Ca(2+)-independent PKC isoforms and probably also for novel cellular targets for the putative second messenger PA.
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Affiliation(s)
- N T Thompson
- Wellcome Foundation Ltd. Beckenham, Kent, England
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31
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Kanoh H, Kanaho Y, Nozawa Y. Pertussis toxin-insensitive G protein mediates carbachol activation of phospholipase D in rat pheochromocytoma PC12 cells. J Neurochem 1992; 59:1786-94. [PMID: 1402922 DOI: 10.1111/j.1471-4159.1992.tb11011.x] [Citation(s) in RCA: 26] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
In the present study, an activation mechanism for phospholipase D (PLD) in [3H]palmitic acid-labeled pheochromocytoma PC12 cells in response to carbachol (CCh) was investigated. PLD activity was assessed by measuring the formation of [3H]phosphatidylethanol ([3H]PEt), the specific marker of PLD activity, in the presence of 0.5% (vol/vol) ethanol. CCh caused a rapid accumulation of [3H]-PEt, which reached a plateau within 1 min, in a concentration-dependent manner. The [3H]PEt formation by CCh was completely antagonized by atropine, demonstrating that the CCh effect was mediated by the muscarinic acetylcholine receptor (mAChR). A tumor promoter, phorbol 12-myristate 13-acetate (PMA), also caused an increase in [3H]-PEt content, which reached a plateau at 30-60 min after exposure, but an inactive phorbol ester, 4 alpha-phorbol 12,13-didecanoate, did not. Although a protein kinase C (PKC) inhibitor, staurosporine (5 microM), blocked PMA-induced [3H]PEt formation by 77%, it had no effect on the CCh-induced formation. These results suggest that mAChR-induced PLD activation is independent of PKC, whereas PLD activation by PMA is mediated by PKC. NaF, a common GTP-binding protein (G protein) activator, and a stable analogue of GTP, guanosine 5'-O-(3-thiotriphosphate) (GTP gamma S), also stimulated [3H]PEt formation in intact and digitonin-permeabilized cells, respectively. GTP, UTP, and CTP were without effect. Furthermore, guanosine 5'-O-(2-thiodiphosphate) significantly inhibited CCh- and GTP gamma S-induced [3H]PEt formation in permeabilized cells but did not inhibit the formation by PMA, and staurosporine (5 microM) had no effect on [3H]PEt formation by GTP gamma S.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- H Kanoh
- Department of Biochemistry, Gifu University School of Medicine, Japan
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32
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McKenzie F, Seuwen K, Pouysségur J. Stimulation of phosphatidylcholine breakdown by thrombin and carbachol but not by tyrosine kinase receptor ligands in cells transfected with M1 muscarinic receptors. Rapid desensitization of phosphocholine-specific (PC) phospholipase D but sustained activity of PC-phospholipase C. J Biol Chem 1992. [DOI: 10.1016/s0021-9258(18)50013-2] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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33
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Kanoh H, Ohbayashi H, Matsuda Y, Nonomura Y, Nozawa Y. Enhancing effect of wortmannin on muscarinic stimulation of phospholipase D in rat pheochromocytoma PC12 cells. Biochem Biophys Res Commun 1992; 188:510-5. [PMID: 1445294 DOI: 10.1016/0006-291x(92)91085-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Wortmannin, a specific inhibitor of myosin light chain kinase (MLCK), enhanced carbachol-induced formation of [3H]phosphatidylethanol ([3H]PEt), a marker of phospholipase D (PLD) activity, in [3H]palmitic acid-labeled PC12 cells. The apparent EC50 value was 1.5 microM, and the effect was maximal at 3 microM and slightly attenuated at higher concentration. Wortmannin alone had no significant effect on [3H]PEt formation. The enhancing effect of wortmannin was observed at the initial increasing phase of [3H]PEt formation but not at the subsequent plateau phase. Wortmannin enhanced also phorbol ester-induced PLD activation. Although the precise mechanism remains to be clarified, these results suggest that MLCK may be involved in PLD regulation in PC12 cells.
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Affiliation(s)
- H Kanoh
- Department of Biochemistry, Gifu University School of Medicine, Japan
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34
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Huang C, Wykle R, Daniel L, Cabot M. Identification of phosphatidylcholine-selective and phosphatidylinositol-selective phospholipases D in Madin-Darby canine kidney cells. J Biol Chem 1992. [DOI: 10.1016/s0021-9258(18)41863-7] [Citation(s) in RCA: 63] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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35
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Koch B, Lutz-Bucher B. Pituitary adenylate cyclase polypeptide (PACAP) stimulates cyclic AMP formation in pituitary fibroblasts and 3T3 tumor fibroblasts: lack of enhancement by protein kinase C activation. Mol Cell Endocrinol 1992; 87:79-86. [PMID: 1280235 DOI: 10.1016/0303-7207(92)90235-x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
A number of neuropeptides were shown to produce potent mitogenic effects on Swiss 3T3 fibroblasts by activating the phospholipase C pathway. Here we provide evidence for the activation by PACAP of the adenylate cyclase pathway in 3T3, as well as in non-tumoral pituitary fibroblasts, similarly to what was seen in pituitary endocrine cells. In these cells, PACAP triggered elevation of both intracellular and extracellular contents of cAMP and the effect was time- and dose-dependent, with half-maximal stimulations being induced with about 0.1 nM. Following activation of protein kinase C (PKC) by the phorbol ester phorbol 12-myristate 13-acetate (PMA), PACAP-induced cAMP production was amplified in pituitary endocrine cells, but was either unchanged or dampened in 3T3 and pituitary fibroblasts, respectively. Pretreatment of cells with pertussis toxin (PT) failed to change the effect of PMA on PACAP-stimulated adenylate cyclase activity, irrespective of the cell type being used. However, PT dramatically reduced the potentiation by PMA of cAMP production enhanced by forskolin in 3T3 cells. These results provide new evidence pointing to the presence in fibroblasts of receptors for PACAP, coupled to cAMP production, which may play a role in the modulation of the mitogenic signal. They also indicate that, compared with pituitary endocrine cells, PKC activation in fibroblasts differentially affected PACAP-induced cAMP formation and that these effects were unaltered upon inhibition by PT of Gi-like proteins.
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Affiliation(s)
- B Koch
- Institut de Physiologie, CNRS URA 1446, Université Louis Pasteur, Strasbourg, France
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36
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Huang C, Cabot MC. Phospholipase D activity in nontransformed and transformed fibroblasts. BIOCHIMICA ET BIOPHYSICA ACTA 1992; 1127:242-8. [PMID: 1324732 DOI: 10.1016/0005-2760(92)90227-m] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Rat embryo fibroblasts (REF52 cells) and the simian virus 40 transformed derivative (WT6 Ag6) were employed to characterize phospholipase D (PLD) activity in normal and transformed cells. In cells prelabeled with [3H]myristic acid or [3H]glycerol and treated with 12-O-tetradecanoylphorbol-13-acetate (TPA, 50 ng/ml medium) or vasopressin (VP, 100 ng/ml medium) in the presence of ethanol, the formation of labeled phosphatidylethanol (PEt) was 3- to 5-fold higher in REF52 cells than in the transformed cells. The transphosphatidylation of phosphatidylcholine (PC) to PEt was further examined in cell-free assay systems. Results demonstrated that the formation of PEt in the cell-free assays was dependent on the mode of substrate presentation and the source of the PC. With endogenous membrane-bound substrate, the formation of [3H]myristoyl-PEt was 5-fold higher in homogenates derived from normal cells as compared to transformed cell homogenates. In experiments using exogenous labeled PC isolated from either REF52 or transformed cells as substrate, cell-free PLD activity differed greatly with regard to the source of the PC. The formation of PEt from REF52-derived PC was approx. 4-fold higher as compared to PEt formed with PC derived from the transformed cells, irrespective of enzyme source. The results demonstrate that PLD in intact nontransformed fibroblasts is activatable by TPA and VP to a greater extent than in the transformed counterpart. The results from cell-free assays suggest that PLD activity is more dependent on the type of PC substrate than on the source of the enzyme.
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Affiliation(s)
- C Huang
- Department of Biochemistry, Bowman Gray School of Medicine, Wake Forest University, Winston-Salem, NC 27157-1016
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Fukami K, Takenawa T. Phosphatidic acid that accumulates in platelet-derived growth factor-stimulated Balb/c 3T3 cells is a potential mitogenic signal. J Biol Chem 1992. [DOI: 10.1016/s0021-9258(19)49864-5] [Citation(s) in RCA: 151] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
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Llahi S, Fain J. Alpha 1-adrenergic receptor-mediated activation of phospholipase D in rat cerebral cortex. J Biol Chem 1992. [DOI: 10.1016/s0021-9258(19)50578-6] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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Fällman M, Gullberg M, Hellberg C, Andersson T. Complement receptor-mediated phagocytosis is associated with accumulation of phosphatidylcholine-derived diglyceride in human neutrophils. Involvement of phospholipase D and direct evidence for a positive feedback signal of protein kinase. J Biol Chem 1992. [DOI: 10.1016/s0021-9258(18)45931-5] [Citation(s) in RCA: 55] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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Cook SJ, Wakelam MJ. Phospholipases C and D in mitogenic signal transduction. Rev Physiol Biochem Pharmacol 1992; 119:13-45. [PMID: 1604152 DOI: 10.1007/3540551921_2] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Affiliation(s)
- S J Cook
- Department of Molecular Biology, Cetus Corporation, Emeryville, CA 94608
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Bishop WR, Pachter JA, Pai JK. Regulation of phospholipid hydrolysis and second messenger formation by protein kinase C. ADVANCES IN ENZYME REGULATION 1992; 32:177-92. [PMID: 1323204 DOI: 10.1016/0065-2571(92)90016-s] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
The binding of a variety of agonists to their receptors leads to the breakdown of membrane phospholipids and the formation of intracellular second messengers. Hydrolysis of inositol phospholipids by phospholipase C results in the formation of two second messengers, inositol-1,4,5-trisphosphate which mobilizes intracellular calcium and the neutral lipid diacylglycerol (DAG) which binds to and activates protein kinase C (PKC). PKC is actually a family of homologous serine/threonine protein kinases which play a central role in regulation of growth, differentiation and secretion reactions in a variety of cell types. In addition to these feedforward roles of PKC, it is thought to play an important feedback role, regulating early events in signal transduction. To explore these feedback functions we have examined the effect of PKC inhibitors on second messenger formation in thrombin-stimulated human platelets (a rapidly responding system) and the effect of PKC overexpression on second messenger formation and mitogenesis in rat fibroblasts (a system where sustained signaling occurs). Treatment of platelets with inhibitors of PKC potentiates DAG mass formation in response to thrombin while prior activation of PKC with phorbol esters blocks DAG mass formation, consistent with PKC playing a negative feedback role, inhibiting inositol phospholipid breakdown. DAG can also be formed by the sequential hydrolysis of phosphatidylcholine by phospholipase D and phosphatidic acid phosphohydrolase. This is a minor reaction in the rapidly responding platelet system, but may play a role in sustained signaling events. We have found that fibroblasts which overexpress the beta 1 isozyme of PKC display greatly enhanced DAG formation and phospholipase D activation in response to phorbol ester treatment. Upon stimulation of fibroblasts with thrombin, phospholipase D activation is also enhanced by PKC overexpression while formation of inositol phosphates is suppressed. These data suggest that PKC may act as a switch, terminating inositol phospholipid hydrolysis and activating the hydrolysis of phosphatidylcholine. Furthermore, we have observed a strong correlation between activation of phospholipase D and mitogenesis, suggesting an important role for this enzyme in long-term cellular responses to activation.
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Affiliation(s)
- W R Bishop
- Department of Microbiology, Schering-Plough Research, Bloomfield, NJ 07003
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Abstract
In the present study evidence is provided for the existence of phospholipase D (PLD) activity in rat Leydig cells. Leydig cells were cultured and labelled with [3H]myristic acid. In the presence of ethanol, phorbol 12-myristate 13-acetate (PMA) stimulated the formation of [3H]phosphatidylethanol ([3H]PEt) in a dose-dependent manner at the expense of [3H]phosphatidic acid ([3H]PA). In cells prelabelled with [3H]choline, PMA caused a rapid increase in intracellular free [3H]choline. The time course of [3H]PEt formation was similar to the time course of intracellular [3H]choline formation. The data taken together support the notion that PMA stimulates phosphatidylcholine (PC) hydrolysis by a mechanism, which principally involves PLD. Activation of PLD by PMA was inhibited by long-term pretreatment of cells with PMA to downregulate protein kinase C (PKC) and by pretreatment with staurosporine. These data support the notion that activation of PLD by PMA is dependent on PKC. Arginine vasopressin (AVP) caused a rapid stimulation of PLD activity in the cells. This activation was inhibited after down-regulation of PKC, indicating that the agonist acts by a mechanism similar to that of PMA.
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Affiliation(s)
- A M Vinggaard
- Department of Biological Sciences, Royal Danish School of Pharmacy, Copenhagen
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Cook SJ, Wakelam MJ. Stimulated phosphatidylcholine hydrolysis as a signal transduction pathway in mitogenesis. Cell Signal 1991; 3:273-82. [PMID: 1931481 DOI: 10.1016/0898-6568(91)90055-y] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Affiliation(s)
- S J Cook
- Department of Molecular Biology, Cetus Corporation, Emeryville, CA 94608
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