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Eurtivong C, Leung E, Sharma N, Leung IKH, Reynisson J. Phosphatidylcholine-Specific Phospholipase C as a Promising Drug Target. Molecules 2023; 28:5637. [PMID: 37570610 PMCID: PMC10420013 DOI: 10.3390/molecules28155637] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2023] [Revised: 07/12/2023] [Accepted: 07/24/2023] [Indexed: 08/13/2023] Open
Abstract
Phosphatidylcholine-specific phospholipase C (PC-PLC) is an enzyme that catalyzes the formation of the important secondary messengers phosphocholine and diacylglycerol (DAG) from phosphatidylcholine. Although PC-PLC has been linked to the progression of many pathological conditions, including cancer, atherosclerosis, inflammation and neuronal cell death, studies of PC-PLC on the protein level have been somewhat neglected with relatively scarce data. To date, the human gene expressing PC-PLC has not yet been found, and the only protein structure of PC-PLC that has been solved was from Bacillus cereus (PC-PLCBc). Nonetheless, there is evidence for PC-PLC activity as a human functional equivalent of its prokaryotic counterpart. Additionally, inhibitors of PC-PLCBc have been developed as potential therapeutic agents. The most notable classes include 2-aminohydroxamic acids, xanthates, N,N'-hydroxyureas, phospholipid analogues, 1,4-oxazepines, pyrido[3,4-b]indoles, morpholinobenzoic acids and univalent ions. However, many medicinal chemistry studies lack evidence for their cellular and in vivo effects, which hampers the progression of the inhibitors towards the clinic. This review outlines the pathological implications of PC-PLC and highlights current progress and future challenges in the development of PC-PLC inhibitors from the literature.
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Affiliation(s)
- Chatchakorn Eurtivong
- Department of Pharmaceutical Chemistry, Faculty of Pharmacy, Mahidol University, 447 Si Ayutthaya Road, Ratchathewi, Bangkok 10400, Thailand
| | - Euphemia Leung
- Auckland Cancer Society Research Centre, The University of Auckland, Private Bag 92019, Auckland 1142, New Zealand;
| | - Nabangshu Sharma
- School of Chemical Sciences, The University of Auckland, Private Bag 92019, Auckland 1142, New Zealand;
- Scion (New Zealand Forest Research Institute), Te Papa Tipu Innovation Park, 49 Sala Street, Rotorua 3010, New Zealand
| | - Ivanhoe K. H. Leung
- School of Chemistry and Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, 30 Flemington Rd, Parkville, VIC 3052, Australia;
| | - Jóhannes Reynisson
- School of Pharmacy and Bioengineering, Keele University, Newcastle-under-Lyme ST5 5BG, UK;
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2
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Sharma N, Langley RJ, Eurtivong C, Leung E, Dixon RJ, Paulin EK, Rees SWP, Pilkington LI, Barker D, Reynisson J, Leung IKH. An optimised MALDI-TOF assay for phosphatidylcholine-specific phospholipase C. ANALYTICAL METHODS : ADVANCING METHODS AND APPLICATIONS 2021; 13:491-496. [PMID: 33432952 DOI: 10.1039/d0ay02208j] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
The Bacillus cereus phosphatidylcholine-specific phospholipase C (PC-PLCBc) is an enzyme that catalyses the hydrolysis of phosphatidylcholines into phosphocholine and 1,2-diacylglycerols. PC-PLCBc has found applications in both the food industry and in medicinal chemistry. Herein, we report our work in the development and optimisation of a matrix assisted laser desorption ionisation time-of-flight (MALDI-TOF) mass spectrometry-based assay to monitor PC-PLCBc activity. The use of one-phase and two-phase reaction systems to assess the inhibition of PC-PLCBc with different structural classes of inhibitors was compared. We also highlighted the advantage of our assay over the commonly used commercially available Amplex Red assay. This method will also be applicable to work on the activity and inhibition of other phospholipases.
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Affiliation(s)
- Nabangshu Sharma
- School of Chemical Sciences, The University of Auckland, Private Bag 92019, Victoria Street West, Auckland 1142, New Zealand.
| | - Ries J Langley
- Maurice Wilkins Centre for Molecular Biodiscovery, The University of Auckland, Private Bag 92019, Victoria Street West, Auckland 1142, New Zealand and Department of Molecular Medicine and Pathology, School of Medical Sciences, The University of Auckland, Private Bag 92019, Victoria Street West, Auckland 1142, New Zealand
| | - Chatchakorn Eurtivong
- Program in Chemical Sciences, Chulabhorn Graduate Institute, Chulabhorn Royal Academy, Bangkok 10210, Thailand and Center of Excellence on Environmental Health and Toxicology (EHT), Commission on Higher Education (CHE), Ministry of Education, Bangkok 10400, Thailand
| | - Euphemia Leung
- Maurice Wilkins Centre for Molecular Biodiscovery, The University of Auckland, Private Bag 92019, Victoria Street West, Auckland 1142, New Zealand and Department of Molecular Medicine and Pathology, School of Medical Sciences, The University of Auckland, Private Bag 92019, Victoria Street West, Auckland 1142, New Zealand and Auckland Cancer Society Research Centre, School of Medical Sciences, The University of Auckland, Private Bag 92019, Victoria Street West, Auckland 1142, New Zealand
| | - Ryan Joseph Dixon
- School of Chemical Sciences, The University of Auckland, Private Bag 92019, Victoria Street West, Auckland 1142, New Zealand.
| | - Emily K Paulin
- School of Chemical Sciences, The University of Auckland, Private Bag 92019, Victoria Street West, Auckland 1142, New Zealand.
| | - Shaun W P Rees
- School of Chemical Sciences, The University of Auckland, Private Bag 92019, Victoria Street West, Auckland 1142, New Zealand.
| | - Lisa I Pilkington
- School of Chemical Sciences, The University of Auckland, Private Bag 92019, Victoria Street West, Auckland 1142, New Zealand.
| | - David Barker
- School of Chemical Sciences, The University of Auckland, Private Bag 92019, Victoria Street West, Auckland 1142, New Zealand. and Centre for Green Chemical Science, The University of Auckland, Private Bag 92019, Victoria Street West, Auckland 1142, New Zealand and The MacDiarmid Institute for Advanced Materials and Nanotechnology, Victoria University of Wellington, PO Box 600, Wellington 6140, New Zealand
| | - Jóhannes Reynisson
- School of Chemical Sciences, The University of Auckland, Private Bag 92019, Victoria Street West, Auckland 1142, New Zealand. and School of Pharmacy and Bioengineering, Keele University, Staffordshire ST5 5BG, UK
| | - Ivanhoe K H Leung
- School of Chemical Sciences, The University of Auckland, Private Bag 92019, Victoria Street West, Auckland 1142, New Zealand. and Maurice Wilkins Centre for Molecular Biodiscovery, The University of Auckland, Private Bag 92019, Victoria Street West, Auckland 1142, New Zealand and Centre for Green Chemical Science, The University of Auckland, Private Bag 92019, Victoria Street West, Auckland 1142, New Zealand
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3
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Vakalopoulou E, Buchmaier C, Pein A, Saf R, Fischer RC, Torvisco A, Warchomicka F, Rath T, Trimmel G. Synthesis and characterization of zinc di( O-2,2-dimethylpentan-3-yl dithiocarbonates) bearing pyridine or tetramethylethylenediamine coligands and investigation of their thermal conversion mechanisms towards nanocrystalline zinc sulfide. Dalton Trans 2020; 49:14564-14575. [PMID: 33107536 DOI: 10.1039/d0dt03065a] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Metal xanthates are versatile single source precursors for the preparation of various metal sulfides. In this study, we present the synthesis of the two novel zinc xanthate complexes bis(O-2,2-dimethylpentan-3-yl-dithiocarbonato)(N,N,N',N'-tetramethylethylenediamine)zinc(ii) and bis(O-2,2-dimethylpentan-3-yl-dithiocarbonato)(pyridine)zinc(ii). A thorough investigation of these compounds revealed distinct differences in their structural and thermal properties. While in the complex containing the chelating tetramethylethylenediamine, the xanthate groups coordinate in a monodentate way, they are bidentally coordinated to the zinc atom in the pyridine containing complex. Both compounds show a two-step thermal decomposition with an onset temperature of 151 °C and 156 °C for the tetramethylethylenediamine and pyridine containing complex, respectively. Moreover, different mechanisms are revealed for the two phases of the decomposition based on high resolution mass spectrometry investigations. By the thermal conversion process nanocrystalline zinc sulfide is produced and the coligand significantly influences its primary crystallite size, which is 4.4 nm using the tetramethylethylenediamine and 11.4 nm using the pyridine containing complex for samples prepared at a temperature of 400 °C.
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Affiliation(s)
- Efthymia Vakalopoulou
- Institute for Chemistry and Technology of Materials (ICTM), NAWI Graz, Graz University of Technology, Stremayrgasse 9, 8010 Graz, Austria.
| | - Christine Buchmaier
- Institute for Chemistry and Technology of Materials (ICTM), NAWI Graz, Graz University of Technology, Stremayrgasse 9, 8010 Graz, Austria.
| | - Andreas Pein
- Institute for Chemistry and Technology of Materials (ICTM), NAWI Graz, Graz University of Technology, Stremayrgasse 9, 8010 Graz, Austria.
| | - Robert Saf
- Institute for Chemistry and Technology of Materials (ICTM), NAWI Graz, Graz University of Technology, Stremayrgasse 9, 8010 Graz, Austria.
| | - Roland C Fischer
- Institute of Inorganic Chemistry, NAWI Graz, Graz University of Technology, Stremayrgasse 9, 8010 Graz, Austria
| | - Ana Torvisco
- Institute of Inorganic Chemistry, NAWI Graz, Graz University of Technology, Stremayrgasse 9, 8010 Graz, Austria
| | - Fernando Warchomicka
- Institute of Materials Science, Joining and Forming, Graz University of Technology, Kopernikusgasse 24, 8010, Graz, Austria
| | - Thomas Rath
- Institute for Chemistry and Technology of Materials (ICTM), NAWI Graz, Graz University of Technology, Stremayrgasse 9, 8010 Graz, Austria.
| | - Gregor Trimmel
- Institute for Chemistry and Technology of Materials (ICTM), NAWI Graz, Graz University of Technology, Stremayrgasse 9, 8010 Graz, Austria.
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4
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Huang W, Carr AJ, Hajicek N, Sokolovski M, Siraliev-Perez E, Hardy PB, Pearce KH, Sondek J, Zhang Q. A High-Throughput Assay to Identify Allosteric Inhibitors of the PLC-γ Isozymes Operating at Membranes. Biochemistry 2020; 59:4029-4038. [PMID: 33028071 DOI: 10.1021/acs.biochem.0c00511] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The two phospholipase C-γ (PLC-γ) isozymes are major signaling hubs and emerging therapeutic targets for various diseases, yet there are no selective inhibitors for these enzymes. We have developed a high-throughput, liposome-based assay that features XY-69, a fluorogenic, membrane-associated reporter for mammalian PLC isozymes. The assay was validated using a pilot screen of the Library of Pharmacologically Active Compounds 1280 (LOPAC1280) in 384-well format; it is highly reproducible and has the potential to capture both orthosteric and allosteric inhibitors. Selected hit compounds were confirmed with secondary assays, and further profiling led to the interesting discovery that adenosine triphosphate potently inhibits the PLC-γ isozymes through noncompetitive inhibition, raising the intriguing possibility of endogenous, nucleotide-dependent regulation of these phospholipases. These results highlight the merit of the assay platform for large scale screening of chemical libraries to identify allosteric modulators of the PLC-γ isozymes as chemical probes and for drug discovery.
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5
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Zhao Y, Su L, Li K, Zhao B. Discovery of novel PC‐PLC activity inhibitors. Chem Biol Drug Des 2019; 95:380-387. [DOI: 10.1111/cbdd.13606] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2019] [Revised: 06/13/2019] [Accepted: 08/03/2019] [Indexed: 12/31/2022]
Affiliation(s)
- YanChun Zhao
- Jinan Hangchen Biotechnology Co., Ltd. Jinan China
| | - Le Su
- State Key Laboratory of Biobased Material and Green Papermaking School of Bioengineering Shandong Academy of Sciences Qilu University of Technology Jinan China
| | - Kunlun Li
- Jinan Hangchen Biotechnology Co., Ltd. Jinan China
| | - BaoXiang Zhao
- Institute of Organic Chemistry School of Chemistry and Chemical Engineering Shandong University Jinan China
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6
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Potential therapeutic targets for atherosclerosis in sphingolipid metabolism. Clin Sci (Lond) 2019; 133:763-776. [PMID: 30890654 PMCID: PMC6422862 DOI: 10.1042/cs20180911] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2018] [Revised: 02/13/2019] [Accepted: 02/14/2019] [Indexed: 12/14/2022]
Abstract
Sphingolipids, such as sphingomyelins, ceramides, glycosphingolipids, and sphingosine-1-phosphates (S1P) are a large group of structurally and functionally diverse molecules. Some specific species are found associated with atherogenesis and provide novel therapeutic targets. Herein, we briefly review how sphingolipids are implicated in the progression of atherosclerosis and related diseases, and then we discuss the potential therapy options by targetting several key enzymes in sphingolipid metabolism.
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7
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Adada M, Luberto C, Canals D. Inhibitors of the sphingomyelin cycle: Sphingomyelin synthases and sphingomyelinases. Chem Phys Lipids 2016. [DOI: 10.1016/j.chemphyslip.2015.07.008] [Citation(s) in RCA: 68] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
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8
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Kato M, Hammam MAS, Taniguchi T, Suga Y, Monde K. What Is the True Structure of D609, a Widely Used Lipid Related Enzyme Inhibitor? Org Lett 2016; 18:768-71. [DOI: 10.1021/acs.orglett.6b00025] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Affiliation(s)
- Mikako Kato
- Graduate
School of Life Science and ‡Faculty of Advanced Life Science,
Frontier Research Center for Post-Genome Science and Technology, Hokkaido University, Kita 21 Nishi 11, Sapporo 001-0021, Japan
| | - Mostafa A. S. Hammam
- Graduate
School of Life Science and ‡Faculty of Advanced Life Science,
Frontier Research Center for Post-Genome Science and Technology, Hokkaido University, Kita 21 Nishi 11, Sapporo 001-0021, Japan
| | - Tohru Taniguchi
- Graduate
School of Life Science and ‡Faculty of Advanced Life Science,
Frontier Research Center for Post-Genome Science and Technology, Hokkaido University, Kita 21 Nishi 11, Sapporo 001-0021, Japan
| | - Yoshiko Suga
- Graduate
School of Life Science and ‡Faculty of Advanced Life Science,
Frontier Research Center for Post-Genome Science and Technology, Hokkaido University, Kita 21 Nishi 11, Sapporo 001-0021, Japan
| | - Kenji Monde
- Graduate
School of Life Science and ‡Faculty of Advanced Life Science,
Frontier Research Center for Post-Genome Science and Technology, Hokkaido University, Kita 21 Nishi 11, Sapporo 001-0021, Japan
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9
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Recent research progress with phospholipase C from Bacillus cereus. Biotechnol Lett 2015; 38:23-31. [DOI: 10.1007/s10529-015-1962-6] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2015] [Accepted: 09/22/2015] [Indexed: 10/23/2022]
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10
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Dumeunier R, Huber A. Toluene as a novel carrier of xanthates—preparation, use and surrogate of S-tri- and di-chloromethyl xanthates. Tetrahedron Lett 2014. [DOI: 10.1016/j.tetlet.2014.06.030] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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11
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Taniguchi M, Okazaki T. The role of sphingomyelin and sphingomyelin synthases in cell death, proliferation and migration—from cell and animal models to human disorders. Biochim Biophys Acta Mol Cell Biol Lipids 2014; 1841:692-703. [DOI: 10.1016/j.bbalip.2013.12.003] [Citation(s) in RCA: 119] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2013] [Revised: 12/06/2013] [Accepted: 12/09/2013] [Indexed: 12/16/2022]
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12
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Syntheses, Characterization, Thermal, and Antimicrobial Studies of Lanthanum(III) Tolyl/Benzyldithiocarbonates. Bioinorg Chem Appl 2014; 2014:780631. [PMID: 24817836 PMCID: PMC4000956 DOI: 10.1155/2014/780631] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2013] [Accepted: 01/03/2014] [Indexed: 11/17/2022] Open
Abstract
Lanthanum(III) tris(O-tolyl/benzyldithiocarbonates), [La(ROCS2)] (R = o-, m-, p-CH3C6H4 and C6H5CH2), were isolated as yellow solid by the reaction of LaCl3·7H2O with sodium salt of tolyl/benzyldithiocarbonates, ROCS2Na (R = o-, m-, p-CH3C6H4 and C6H5CH2), in methanol under anhydrous conditions in 1 : 3 molar ratio. These complexes have formed adducts with nitrogen and phosphorus donor molecules by straightforward reaction of these complexes with donor ligands, which have the composition of the type [La(ROCS2)3·nL] (where n = 2, L = NC5H5 or P(C6H5)3 and n = 1, L = N2C12H8 or N2C10H8). Elemental analyses, mass, IR, TGA, and heteronuclear NMR (1H, 13C and 31P) spectroscopic studies indicated bidentate mode of bonding by dithiocarbonate ligands leading to hexacoordinated and octacoordinated geometry around the lanthanum atom. Antimicrobial (antifungal and antibacterial) activity of the free ligands and some of the complexes have also been investigated which exhibited significantly more activity for the complexes than the free ligands.
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13
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Erttmann SF, Gekara NO, Fällman M. Bacteria induce prolonged PMN survival via a phosphatidylcholine-specific phospholipase C- and protein kinase C-dependent mechanism. PLoS One 2014; 9:e87859. [PMID: 24498214 PMCID: PMC3909253 DOI: 10.1371/journal.pone.0087859] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2013] [Accepted: 12/31/2013] [Indexed: 01/11/2023] Open
Abstract
Polymorphonuclear leukocytes (PMNs) are essential for the human innate immune defense, limiting expansion of invading microorganisms. PMN turnover is controlled by apoptosis, but the regulating signaling pathways remain elusive, largely due to inherent differences between mice and humans that undermine use of mouse models for understanding human PMN biology. Here, we aim to elucidate signal transduction mediating survival of human peripheral blood PMNs in response to bacteria, such as Yersinia pseudotuberculosis, an enteropathogen that causes the gastro-intestinal disease yersiniosis, as well as Escherichia coli and Staphylococcus aureus. Determinations of cell death reveal that uninfected control cells undergo apoptosis, while PMNs infected with either Gram-positive or -negative bacteria show profoundly increased survival. Infected cells exhibit decreased caspase 3 and 8 activities, increased mitochondrial integrity and are resistant to apoptosis induced by a death receptor ligand. This bacteria-induced response is accompanied by pro-inflammatory cytokine production including interleukin-8 and tumor necrosis factor-α competent to attract additional PMNs. Using agonists and pharmacological inhibitors, we show participation of Toll-like receptor 2 and 4, and interestingly, that protein kinase C (PKC) and phosphatidylcholine-specific phospholipase C (PC-PLC), but not tyrosine kinases or phosphatidylinositol-specific phospholipase C (PI-PLC) are key players in this dual PMN response. Our findings indicate the importance of prolonged PMN survival in response to bacteria, where general signaling pathways ensure complete exploitation of PMN anti-microbial capacity.
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Affiliation(s)
- Saskia F. Erttmann
- Department of Molecular Biology, Umeå Centre for Microbial Research (UCMR), Laboratory for Molecular Infection Medicine Sweden (MIMS), Umeå University, Umeå Sweden
| | - Nelson O. Gekara
- Department of Molecular Biology, Umeå Centre for Microbial Research (UCMR), Laboratory for Molecular Infection Medicine Sweden (MIMS), Umeå University, Umeå Sweden
| | - Maria Fällman
- Department of Molecular Biology, Umeå Centre for Microbial Research (UCMR), Laboratory for Molecular Infection Medicine Sweden (MIMS), Umeå University, Umeå Sweden
- * E-mail:
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14
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Martin ML, Liebisch G, Lehneis S, Schmitz G, Alonso-Sande M, Bestard-Escalas J, Lopez DH, García-Verdugo JM, Soriano-Navarro M, Busquets X, Escribá PV, Barceló-Coblijn G. Sustained activation of sphingomyelin synthase by 2-hydroxyoleic acid induces sphingolipidosis in tumor cells. J Lipid Res 2013; 54:1457-65. [PMID: 23471028 PMCID: PMC3653406 DOI: 10.1194/jlr.m036749] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2013] [Revised: 03/07/2013] [Indexed: 12/22/2022] Open
Abstract
The mechanism of action of 2-hydroxyoleic acid (2OHOA), a potent antitumor drug, involves the rapid and specific activation of sphingomyelin synthase (SMS), leading to a 4-fold increase in SM mass in tumor cells. In the present study, we investigated the source of the ceramides required to sustain this dramatic increase in SM. Through radioactive and fluorescent labeling, we demonstrated that sphingolipid metabolism was altered by a 24 h exposure to 2OHOA, and we observed a consistent increase in the number of lysosomes and the presence of unidentified storage materials in treated cells. Mass spectroscopy revealed that different sphingolipid classes accumulated in human glioma U118 cells after exposure to 2OHOA, demonstrating a specific effect on C16-, C20-, and C22-containing sphingolipids. Based on these findings, we propose that the demand for ceramides required to sustain the SMS activation (ca. 200-fold higher than the basal level) profoundly modifies both sphingolipid and phospholipid metabolism. As the treatment is prolonged, tumor cells fail to adequately metabolize sphingolipids, leading to a situation resembling sphingolipidosis, whereby cell viability is compromised.
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Affiliation(s)
- Maria Laura Martin
- Laboratory of Molecular Cell Biomedicine, Department of Biology, University Institute for Research into Health Sciences (IUNICS), University of the Balearic Islands, E-07122 Palma, Balearic Islands, Spain
| | - Gerhard Liebisch
- Institute for Clinical Chemistry and Laboratory Medicine, University of Regensburg, 93042 Regensburg, Germany; and
| | - Stefan Lehneis
- Institute for Clinical Chemistry and Laboratory Medicine, University of Regensburg, 93042 Regensburg, Germany; and
| | - Gerd Schmitz
- Institute for Clinical Chemistry and Laboratory Medicine, University of Regensburg, 93042 Regensburg, Germany; and
| | - María Alonso-Sande
- Laboratory of Molecular Cell Biomedicine, Department of Biology, University Institute for Research into Health Sciences (IUNICS), University of the Balearic Islands, E-07122 Palma, Balearic Islands, Spain
| | - Joan Bestard-Escalas
- Laboratory of Molecular Cell Biomedicine, Department of Biology, University Institute for Research into Health Sciences (IUNICS), University of the Balearic Islands, E-07122 Palma, Balearic Islands, Spain
| | - Daniel H. Lopez
- Laboratory of Molecular Cell Biomedicine, Department of Biology, University Institute for Research into Health Sciences (IUNICS), University of the Balearic Islands, E-07122 Palma, Balearic Islands, Spain
| | - José Manuel García-Verdugo
- Laboratorio de Morfología Celular, Unidad Mixta Centre d'Investigació Príncep Felipe-Universitat de València Estudis Generals (CIPF-UVEG), Centro de Investigación Biomédica en Red, Enfermedades Neurodegenerativas (CIBERNED), 46013 Valencia, Spain
| | - Mario Soriano-Navarro
- Laboratorio de Morfología Celular, Unidad Mixta Centre d'Investigació Príncep Felipe-Universitat de València Estudis Generals (CIPF-UVEG), Centro de Investigación Biomédica en Red, Enfermedades Neurodegenerativas (CIBERNED), 46013 Valencia, Spain
| | - Xavier Busquets
- Laboratory of Molecular Cell Biomedicine, Department of Biology, University Institute for Research into Health Sciences (IUNICS), University of the Balearic Islands, E-07122 Palma, Balearic Islands, Spain
| | - Pablo V. Escribá
- Laboratory of Molecular Cell Biomedicine, Department of Biology, University Institute for Research into Health Sciences (IUNICS), University of the Balearic Islands, E-07122 Palma, Balearic Islands, Spain
| | - Gwendolyn Barceló-Coblijn
- Laboratory of Molecular Cell Biomedicine, Department of Biology, University Institute for Research into Health Sciences (IUNICS), University of the Balearic Islands, E-07122 Palma, Balearic Islands, Spain
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15
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Gao X, Gong H, Men P, Zhou L, Ye D. Design, Synthesis, and Biological Evaluation of Novel Dual Inhibitors of Secretory Phospholipase A2 and Sphingomyelin Synthase. CHINESE J CHEM 2013. [DOI: 10.1002/cjoc.201300079] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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16
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Fischereder A, Schenk A, Rath T, Haas W, Delbos S, Gougaud C, Naghavi N, Pateter A, Saf R, Schenk D, Edler M, Bohnemann K, Reichmann A, Chernev B, Hofer F, Trimmel G. Solution-processed copper zinc tin sulfide thin films from metal xanthate precursors. MONATSHEFTE FUR CHEMIE 2013. [DOI: 10.1007/s00706-012-0882-6] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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17
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Zama K, Mitsutake S, Watanabe K, Okazaki T, Igarashi Y. A sensitive cell-based method to screen for selective inhibitors of SMS1 or SMS2 using HPLC and a fluorescent substrate. Chem Phys Lipids 2012; 165:760-8. [PMID: 23063490 DOI: 10.1016/j.chemphyslip.2012.09.003] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2012] [Revised: 09/27/2012] [Accepted: 09/30/2012] [Indexed: 01/09/2023]
Abstract
Recent studies have revealed that sphingomyelin (SM) is involved in metabolic syndrome and is a new target of an anti-metabolic syndrome drug. Deficiencies in the enzyme SM synthase 1 (SMS1) result in severe abnormalities, whereas deficiencies in SMS2 do not. SMS1 and SMS2 synthesize SM under similar conditions, so their respective activities cannot be measured separately. We report here on a sensitive, high-throughput and reliable cell-based method to separately measure each SMS activity and to screen for SMS-specific inhibitors, using HPLC and fluorescent ceramide (Cer) analogs. We isolated SMS-null cells and stably transfected them with SMS1 or SMS2. Using these cells, individual SMS activities could be measured separately. Fluorescent Cer, SM, and glucosylceramide analogs could be separated within 4 min by HPLC using an NH(2) column. SMS activities of SMS1- or SMS2-expressing cells seeded in a single well of a 96-well plate could be measured using HPLC and fluorescent Cer analogs. This method clearly demonstrated that treatment of the cells with their respective siRNA or D609, an inhibitor of SMS, resulted in a significant decrease in each SMS activity. These results indicate that our newly developed method can be utilized for screening therapeutics against metabolic syndrome that target SMS2.
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Affiliation(s)
- Kota Zama
- Department of Biomembrane and Biofunctional Chemistry and Developmental Biotechnology, Faculty of Advanced Life Science, Hokkaido University, Sapporo 001-0021, Japan
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Yachi R, Uchida Y, Balakrishna BH, Anderluh G, Kobayashi T, Taguchi T, Arai H. Subcellular localization of sphingomyelin revealed by two toxin-based probes in mammalian cells. Genes Cells 2012; 17:720-7. [DOI: 10.1111/j.1365-2443.2012.01621.x] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2012] [Accepted: 05/08/2012] [Indexed: 11/29/2022]
Affiliation(s)
- Rieko Yachi
- Graduate School of Pharmaceutical Sciences; University of Tokyo; Tokyo; 113-0033; Japan
| | - Yasunori Uchida
- Graduate School of Pharmaceutical Sciences; University of Tokyo; Tokyo; 113-0033; Japan
| | | | | | | | - Tomohiko Taguchi
- Graduate School of Pharmaceutical Sciences; University of Tokyo; Tokyo; 113-0033; Japan
| | - Hiroyuki Arai
- Graduate School of Pharmaceutical Sciences; University of Tokyo; Tokyo; 113-0033; Japan
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Kalgotra N, Gupta B, Kumar K, Pandey SK. O-Tolyldithiocarbonate Complexes of Iron(II) and Iron(III). PHOSPHORUS SULFUR 2012. [DOI: 10.1080/10426507.2011.614299] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/14/2022]
Affiliation(s)
- Nidhi Kalgotra
- a Department of Chemistry , University of Jammu , Jammu , Jammu and Kashmir , India
| | - Bhawana Gupta
- a Department of Chemistry , University of Jammu , Jammu , Jammu and Kashmir , India
| | - Kuldeep Kumar
- a Department of Chemistry , University of Jammu , Jammu , Jammu and Kashmir , India
| | - Sushil K. Pandey
- a Department of Chemistry , University of Jammu , Jammu , Jammu and Kashmir , India
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O-Tolyl/benzyl dithiocarbonates of phosphorus(III) and (V): syntheses and characterization. MONATSHEFTE FUR CHEMIE 2012. [DOI: 10.1007/s00706-011-0704-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/14/2022]
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Adibhatla RM, Hatcher JF, Gusain A. Tricyclodecan-9-yl-xanthogenate (D609) mechanism of actions: a mini-review of literature. Neurochem Res 2011; 37:671-9. [PMID: 22101393 DOI: 10.1007/s11064-011-0659-z] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2011] [Revised: 10/14/2011] [Accepted: 11/10/2011] [Indexed: 12/21/2022]
Abstract
Tricyclodecan-9-yl-xanthogenate (D609) is known for its antiviral and antitumor properties. D609 actions are widely attributed to inhibiting phosphatidylcholine (PC)-specific phospholipase C (PC-PLC). D609 also inhibits sphingomyelin synthase (SMS). PC-PLC and/or SMS inhibition will affect lipid second messengers 1,2-diacylglycerol (DAG) and/or ceramide. Evidence indicates either PC-PLC and/or SMS inhibition affected the cell cycle and arrested proliferation, and stimulated differentiation in various in vitro and in vivo studies. Xanthogenate compounds are also potent antioxidants and D609 reduced Aß-induced toxicity, attributed to its antioxidant properties. Zn²⁺ is necessary for PC-PLC enzymatic activity; inhibition by D609 might be attributed to its Zn²⁺ chelation. D609 has also been proposed to inhibit acidic sphingomyelinase or down-regulate hypoxia inducible factor-1α; however these are down-stream events related to PC-PLC inhibition. Characterization of the mammalian PC-PLC is limited to inhibition of enzymatic activity (frequently measured using Amplex red assay with bacterial PC-PLC as a standard). The mammalian PC-PLC has not been cloned; sequenced and structural information is unavailable. D609 showed promise in cancer studies, reduced atherosclerotic plaques (inhibition of PC-PLC) and cerebral infarction after stroke (PC-PLC or SMS). D609 actions as an antagonist to pro-inflammatory cytokines have been attributed to PC-PLC. The purpose of this review is to comprehensively evaluate the literature and summarize the findings and relevance to cell cycle and CNS pathologies.
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Affiliation(s)
- Rao Muralikrishna Adibhatla
- Department of Neurological Surgery, Clinical Science Center, University of Wisconsin School of Medicine and Public Health, 600 Highland Avenue, Madison, WI 53792-3232, USA.
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22
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Sphingomyelin and sphingomyelin synthase (SMS) in the malignant transformation of glioma cells and in 2-hydroxyoleic acid therapy. Proc Natl Acad Sci U S A 2011; 108:19569-74. [PMID: 22106271 DOI: 10.1073/pnas.1115484108] [Citation(s) in RCA: 125] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
The mechanism of action of 2-hydroxyoleic acid (2OHOA), a potent antitumor compound, has not yet been fully elucidated. Here, we show that human cancer cells have markedly lower levels of sphingomyelin (SM) than nontumor (MRC-5) cells. In this context, 2OHOA treatment strongly augments SM mass (4.6-fold), restoring the levels found in MRC-5 cells, while a loss of phosphatidylethanolamine and phosphatidylcholine is observed (57 and 30%, respectively). The increased SM mass was due to a rapid and highly specific activation of SM synthases (SMS). This effect appeared to be specific against cancer cells as it did not affect nontumor MRC-5 cells. Therefore, low SM levels are associated with the tumorigenic transformation that produces cancer cells. SM accumulation occurred at the plasma membrane and caused an increase in membrane global order and lipid raft packing in model membranes. These modifications would account for the observed alteration by 2OHOA in the localization of proteins involved in cell apoptosis (Fas receptor) or differentiation (Ras). Importantly, SMS inhibition by D609 diminished 2OHOA effect on cell cycle. Therefore, we propose that the regulation of SMS activity in tumor cells is a critical upstream event in 2OHOA antitumor mechanism, which also explains its specificity for cancer cells, its potency, and the lack of undesired side effects. Finally, the specific activation of SMS explains the ability of this compound to trigger cell cycle arrest, cell differentiation, and autophagy or apoptosis in cancer cells.
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González-Bulnes P, González-Roura A, Canals D, Delgado A, Casas J, Llebaria A. 2-aminohydroxamic acid derivatives as inhibitors of Bacillus cereus phosphatidylcholine preferred phospholipase C PC-PLC(Bc). Bioorg Med Chem 2010; 18:8549-55. [PMID: 21071231 DOI: 10.1016/j.bmc.2010.10.031] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2010] [Revised: 09/14/2010] [Accepted: 10/12/2010] [Indexed: 01/18/2023]
Abstract
Phosphatidylcholine preferring phospholipase C (PC-PLC) is an important enzyme that plays a key role in a variety of cellular events and lipid homoeostases. Bacillus cereus phospholipase C (PC-PLC(Bc)) has antigenic similarity with the elusive mammalian PC-PLC, which has not thus far been isolated and purified. Therefore the discovery of inhibitors of PC-PLC(Bc) is of current interest. Here, we describe the synthesis and biological evaluation of a new type of compounds inhibiting PC-PLC(Bc). These compounds have been designed by evolution of previously described 2-aminohydroxamic acid PC-PLC(Bc) inhibitors that block the enzyme by coordination of the zinc active site atoms present in PC-PLC(Bc) [Gonzalez-Roura, A.; Navarro, I.; Delgado, A.; Llebaria, A.; Casas, J. Angew. Chem. Int. Ed.2004, 43, 862]. The new compounds maintain the zinc coordinating groups and possess an extra trimethylammonium function, linked to the hydroxyamide nitrogen by an alkyl chain, which is expected to mimic the trimethylammonium group of the phosphatidylcholine PC-PLC(Bc) substrates. Some of the compounds described inhibit the enzyme with IC(50)'s in the low micromolar range. Unexpectedly, the most potent inhibitors found are those that possess a trimethylammonium group but have chemically blocked the zinc coordinating functionalities. The results obtained suggest that PC-PLC(Bc) inhibition is not due to the interaction of compounds with the phospholipase catalytic zinc atoms, but rather results from the inhibitor cationic group recognition by the PC-PLC(Bc) amino acids involved in choline lipid binding.
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Affiliation(s)
- Patricia González-Bulnes
- Research Unit on BioActive Molecules (RUBAM), Department of Biomedicinal Chemistry, Institute of Advance Chemistry of Catalonia (IQAC-CSIC), Jordi Girona 18-26, 08034 Barcelona, Spain
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24
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Inhibition of phosphatidylcholine-specific phospholipase C downregulates HER2 overexpression on plasma membrane of breast cancer cells. Breast Cancer Res 2010; 12:R27. [PMID: 20462431 PMCID: PMC2917016 DOI: 10.1186/bcr2575] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2009] [Revised: 03/18/2010] [Accepted: 05/12/2010] [Indexed: 12/21/2022] Open
Abstract
Introduction Overexpression on plasma membrane of human epidermal growth factor receptor 2 (HER2) is reported in 25% to 30% of breast cancers. Heterodimer formation with cognate members of the epidermal growth factor receptor (EGFR) family, such as HER3 and EGFR, activates abnormal cell-signalling cascades responsible for tumorigenesis and further transcriptional HER2 gene upregulation. Targeting the molecular mechanisms controlling HER2 overexpression and recycling may effectively deactivate this feedback-amplification loop. We recently showed that inactivation of phosphatidylcholine-specific phospholipase C (PC-PLC) may exert a pivotal role in selectively modulating the expression on the membrane of specific receptors or proteins relevant to cell function. In the present study, we investigated the capability of PC-PLC inhibition to target the molecular mechanisms controlling HER2 overexpression on the membrane of breast cancer cells by altering the rates of its endocytosis and lysosomal degradation. Methods Localization on the membrane and interaction of PC-PLC with HER2, EGFR, and HER3 were investigated on HER2-overexpressing and HER2-low breast cancer cell lines, by using confocal laser scanning microscopy, flow cytometry, cell-surface biotinylation, isolation of lipid rafts, and immunoprecipitation experiments. The effects of the PC-PLC inhibitor tricyclodecan-9-yl-potassium xanthate (D609) on HER2 expression on the membrane and on the levels of overall HER2, HER2-HER3, and HER2-EGFR contents were monitored in the HER2-overexpressing SKBr3 cells, after either transient or continuous receptor engagement with anti-HER2 monoclonal antibodies, including trastuzumab. Changes of HER2 expression and cell proliferation were examined in SKBr3, BT-474, and MDA-MB-453 cells continuously exposed to D609 alone or combined with trastuzumab. Results PC-PLC selectively accumulates on the plasma membrane of HER2-overexpressing cells, where it colocalizes and associates with HER2 in raft domains. PC-PLC inhibition resulted in enhanced HER2 internalization and lysosomal degradation, inducing downmodulation of HER2 expression on the membrane. Moreover, PC-PLC inhibition resulted in strong retardation of HER2 reexpression on the membrane and a decrease in the overall cellular contents of HER2, HER2-HER3, and HER2-EGFR heterodimers. The PC-PLC inhibitor also induced antiproliferative effects, especially in trastuzumab-resistant cells. Conclusions The results pointed to PC-PLC inhibition as a potential means to counteract the tumorigenic effects of HER2 amplification and complement the effectiveness of current HER2-targeting therapies.
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Robichaud JC, van der Veen JN, Yao Z, Trigatti B, Vance DE. Hepatic uptake and metabolism of phosphatidylcholine associated with high density lipoproteins. Biochim Biophys Acta Gen Subj 2009; 1790:538-51. [PMID: 19250958 DOI: 10.1016/j.bbagen.2009.02.010] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2008] [Revised: 02/11/2009] [Accepted: 02/17/2009] [Indexed: 01/20/2023]
Abstract
BACKGROUND Phosphatidylcholine (PC) is the predominant phospholipid associated with high density lipoproteins (HDL). Although the hepatic uptake of cholesteryl esters from HDL is well characterized, much less is known about the fate of PC associated with HDL. Thus, we investigated the uptake and subsequent metabolism of HDL-PC in primary mouse hepatocytes. METHODS AND RESULTS The absence of scavenger receptor-BI resulted in a 30% decrease in cellular incorporation of [(3)H]PC whereas [(3)H]cholesteryl ether uptake was almost completely abolished. Although endocytosis is not involved in the uptake of cholesteryl esters from HDL, we demonstrate that HDL internalization accounts for 40% of HDL-PC uptake. Extracellular remodeling of HDL by secretory phospholipase A(2) significantly enhances HDL lipid uptake. HDL-PC taken up by hepatocytes is partially converted to triacylglycerols via PC-phospholipase C-mediated hydrolysis of PC and incorporation of diacylglycerol into triacylglycerol. The formation of triacylglycerol is independent of scavenger receptor-BI and occurs in extralysosomal compartments. CONCLUSIONS AND GENERAL SIGNIFICANCE These findings indicate that HDL-associated PC is incorporated into primary hepatocytes via a pathway that differs significantly from that of HDL-cholesteryl ester, and shows that HDL-PC is more than a framework molecule, as evidenced by its partial conversion to hepatic triacylglycerol.
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Affiliation(s)
- Julie C Robichaud
- Department of Biochemistry, University of Alberta, Edmonton, Alberta, Canada
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26
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Delgado A, Casas J, Llebaria A, Abad JL, Fabrias G. Inhibitors of sphingolipid metabolism enzymes. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2006; 1758:1957-77. [PMID: 17049336 DOI: 10.1016/j.bbamem.2006.08.017] [Citation(s) in RCA: 141] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Received: 02/01/2006] [Accepted: 08/18/2006] [Indexed: 01/09/2023]
Abstract
Sphingolipids are a family of lipids that play essential roles both as structural cell membrane components and in cell signalling. The cellular contents of the various sphingolipid species are controlled by enzymes involved in their metabolic pathways. In this context, the discovery of small chemical entities able to modify these enzyme activities in a potent and selective way should offer new pharmacological tools and therapeutic agents.
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Affiliation(s)
- Antonio Delgado
- Research Unit on Bioactive Molecules (RUBAM), Department of Biological Organic Chemistry, Chemical and Environmental Research Institute of Barcelona, (IIQAB-C.S.I.C), Jordi Girona 18-26, 08034 Barcelona, Spain
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Mateos MV, Uranga RM, Salvador GA, Giusto NM. Coexistence of phosphatidylcholine-specific phospholipase C and phospholipase D activities in rat cerebral cortex synaptosomes. Lipids 2006; 41:273-80. [PMID: 16711602 DOI: 10.1007/s11745-006-5097-3] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
DAG derived from phosphatidylcholine (PtdCho) acts as a lipid second messenger. It can be generated by the activation of phospholipase D (PLD) and the phosphatidic acid phosphohydrolase type 2 (PAP2) pathway or by a PtdCho-specific phospholipase C (PtdCho-PLC). Our purpose was to study PtdCho-PLC activity in rat cerebral cortex synaptosomes (CC Syn). DAG production was highly stimulated by detergents such as Triton X-100 and sodium deoxycholate. Ethanol and tricyclodecan-9-yl-xanthate potassium salt decreased DAG generation by 42 and 61%, respectively, at 20 min of incubation. These data demonstrate that both the PLD/PAP2 pathway and PtdCho-PLC contribute to DAG generation in CC Syn. PtdCho-PLC activity remained located mainly in the synaptosomal plasma membrane fraction. Kinetic studies showed Km and Vmax values of 350 microM and 3.7 nmol DAG x (mg protein x h)(-1), respectively. Western blot analysis with anti-PtdCho-PLC antibody showed a band of 66 KDa in CC Syn. Our results indicate the presence of a novel DAG-generating pathway in CC Syn in addition to the known PLD/PAP2 pathway.
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Affiliation(s)
- Melina V Mateos
- Instituto de Investigaciones Bioquímicas de Bahía Blanca, Universidad Nacional del Sur and Consejo Nacional de Investigaciones Científicas y Técnicas, CC 857, B8000FWB Bahía Blanca, Argentina
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Perry RJ, Ridgway ND. The role of de novo ceramide synthesis in the mechanism of action of the tricyclic xanthate D609. J Lipid Res 2004; 45:164-73. [PMID: 13130125 DOI: 10.1194/jlr.m300300-jlr200] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The cytotoxic effects of several chemotherapeutic drugs have been linked to elevated de novo ceramide biosynthesis. However, the relationship between the intracellular site(s) of ceramide accumulation and cytotoxicity is poorly understood. Here we examined the relationship between the site of ceramide deposition and inhibition of protein translation and induction of apoptosis by the antitumor/antiviral xanthate, D609. In Chinese hamster ovary (CHO)-K1, HEK-293, and NIH-3T3 cells, D609 caused rapid (1-5 min) and sustained eukaryotic initiation factor 2alpha (eIF2alpha) phosphorylation followed by apoptosis after 24 h. Concurrently, D609 stimulated de novo ceramide synthesis and increased ceramide mass 2-fold by 2 h in CHO-K1 cells. In D609-treated CHO-K1 cells, sphingomyelin synthesis was stimulated by brefeldin A, and C5-DMB-ceramide transport to the Golgi apparatus was blocked, indicating ceramide accumulation in the endoplasmic reticulum (ER). However, D609-mediated eIF2alpha phosphorylation, inhibition of protein synthesis, and apoptosis in CHO-K1 cells were not attenuated by fumonisin B1 or l-cycloserine. Interestingly, short-chain ceramide promoted eIF2alpha phosphorylation and inhibited protein synthesis in CHO-K1 cells, indicating that the effectiveness of endogenous ceramide could be limited by access to signaling pathways. Thus, expansion of the ER ceramide pool by D609 was not implicated in early (eIF2alpha phosphorylation) or late (apoptotic) cytotoxic events.
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Affiliation(s)
- Ryan J Perry
- Department of Pediatrics, Atlantic Research Centre, Dalhousie University, Halifax, Nova Scotia, Canada
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Stonehouse MJ, Cota-Gomez A, Parker SK, Martin WE, Hankin JA, Murphy RC, Chen W, Lim KB, Hackett M, Vasil AI, Vasil ML. A novel class of microbial phosphocholine-specific phospholipases C. Mol Microbiol 2002; 46:661-76. [PMID: 12410824 DOI: 10.1046/j.1365-2958.2002.03194.x] [Citation(s) in RCA: 75] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
In this report we describe the 1,500-fold purification and characterization of the haemolytic phospholipase C (PLC) of Pseudomonas aeruginosa, the paradigm member of a novel PLC/phosphatase superfamily. Members include proteins from Mycobacterium tuberculosis, Bordetella spp., Francisella tularensis and Burkholderia pseudomallei. Purification involved overexpression of the plcHR1,2 operon, ion exchange chromatography and native preparative polyacrylamide gel electrophoresis. Matrix-assisted laser desorption ionization time-of-flight (MALDI-TOF) mass spectrometry confirmed the presence of two proteins in the purified sample with sizes of 17,117.2 Da (PlcR2) and 78,417 Da (PlcH). Additionally, liquid chromatography electrospray mass spectrometry (LCMS) revealed that PlcH and PlcR2 are at a stoichiometry of 1 : 1. Western blot analysis demonstrated that the enzyme purifies as a heterodimeric complex, PlcHR2. PlcHR2 is only active on choline-containing phospholipids. It is equally active on phosphatidylcholine (PC) and sphingomyelin (SM) and is able to hydrolyse plasmenylcholine phospholipids (plasmalogens). Neither PlcHR2 nor the M. tuberculosis homologues are inhibited by D609 a widely used, competitive inhibitor of the Bacillus cereus PLC. PlcH, PlcR2, and the PlcHR2 complex bind calcium. While calcium has no detectable effect on enzymatic activity, it inhibits the haemolytic activity of PlcHR2. In addition to being required for the secretion of PlcH, the chaperone PlcR2 affects both the enzymatic and haemolytic properties of PlcH. Inclusive in these data is the conclusion that the members of this PC-PLC and phosphatase family possess a novel mechanism for the recognition and hydrolysis of their respective substrates.
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Affiliation(s)
- Martin J Stonehouse
- Department of Microbiology, University of Colorado Health Sciences Center, 4200 E. Ninth Ave., Box B-175, Denver, CO 80262, USA
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