51
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Samadi N, Bekele R, Capatos D, Venkatraman G, Sariahmetoglu M, Brindley DN. Regulation of lysophosphatidate signaling by autotaxin and lipid phosphate phosphatases with respect to tumor progression, angiogenesis, metastasis and chemo-resistance. Biochimie 2010; 93:61-70. [PMID: 20709140 DOI: 10.1016/j.biochi.2010.08.002] [Citation(s) in RCA: 88] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2010] [Revised: 08/03/2010] [Accepted: 08/04/2010] [Indexed: 12/21/2022]
Abstract
Evidence from clinical, animal and cell culture studies demonstrates that increased autotaxin (ATX) expression is responsible for enhancing tumor progression, cell migration, metastases, angiogenesis and chemo-resistance. These effects depend mainly on the rapid formation of lysophosphatidate (LPA) by ATX. Circulating LPA has a half-life of about 3 min in mice and it is degraded by the ecto-activities of lipid phosphate phosphatases (LPPs). These enzymes also hydrolyze extracellular sphingosine 1-phosphate (S1P), a potent signal for cell division, survival and angiogenesis. Many aggressive tumor cells express high ATX levels and low LPP activities. This favors the formation of locally high LPA and S1P concentrations. Furthermore, LPPs attenuate signaling downstream of the activation of G-protein coupled receptors and receptor tyrosine kinases. Therefore, we propose that the low expression of LPPs in many tumor cells makes them hypersensitive to growth promoting and survival signals that are provided by LPA, S1P, platelet-derived growth factor (PDGF) and epidermal growth factor (EGF). One of the key signaling pathways in this respect appears to be activation of phospholipase D (PLD) and phosphatidate (PA) production. This is required for the transactivations of the EGFR and PDGFR and also for LPA-induced cell migration. PA also increases the activities of ERK, mTOR, myc and sphingosine kinase-1 (SK-1), which provide individual signals for cells division, survival, chemo-resistance and angiogenesis. This review focuses on the balance of signaling by bioactive lipids including LPA, phosphatidylinositol 3,4,5-trisphosphate, PA and S1P versus the action of ceramides. We will discuss how these lipid mediators interact to produce an aggressive neoplastic phenotype.
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Affiliation(s)
- Nasser Samadi
- Signal Transduction Research Group, Department of Biochemistry, School of Molecular and Systems Medicine, University of Alberta, Edmonton, T6G 2S2 Alberta, Canada
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52
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Han GS, Carman GM. Characterization of the human LPIN1-encoded phosphatidate phosphatase isoforms. J Biol Chem 2010; 285:14628-38. [PMID: 20231281 DOI: 10.1074/jbc.m110.117747] [Citation(s) in RCA: 112] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The human LPIN1 gene encodes the protein lipin 1, which possesses phosphatidate (PA) phosphatase (3-sn-phosphatidate phosphohydrolase; EC 3.1.3.4) activity (Han, G.-S., Wu, W.-I., and Carman, G. M. (2006) J. Biol. Chem. 281, 9210-9218). In this work, we characterized human lipin 1 alpha, beta, and gamma isoforms that were expressed in Escherichia coli and purified to near homogeneity. PA phosphatase activities of the alpha, beta, and gamma isoforms were dependent on Mg(2+) or Mn(2+) ions at pH 7.5 at 37 degrees C. The activities were inhibited by concentrations of Mg(2+) and Mn(2+) above their optimums and by Ca(2+), Zn(2+), N-ethylmaleimide, propranolol, and the sphingoid bases sphingosine and sphinganine. The activities were thermally labile at temperatures above 40 degrees C. The alpha, beta, and gamma activities followed saturation kinetics with respect to the molar concentration of PA (K(m) values of 0.35, 0.24, and 0.11 mm, respectively) but followed positive cooperative (Hill number approximately 2) kinetics with respect to the surface concentration of PA (K(m) values of 4.2, 4.5, and 4.3 mol %, respectively) in Triton X-100/PA-mixed micelles. The turnover numbers (k(cat)) for the alpha, beta, and gamma isoforms were 68.8 + or - 3.5, 42.8 + or - 2.5, and 5.7 + or - 0.2 s(-1), respectively, whereas their energy of activation values were 14.2, 15.5, and 18.5 kcal/mol, respectively. The isoform activities were dependent on PA as a substrate and required at least one unsaturated fatty acyl moiety for maximum activity.
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Affiliation(s)
- Gil-Soo Han
- Department of Food Science and Rutgers Center for Lipid Research, Rutgers University, New Brunswick, New Jersey 08901, USA
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53
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Gangoiti P, Camacho L, Arana L, Ouro A, Granado MH, Brizuela L, Casas J, Fabriás G, Abad JL, Delgado A, Gómez-Muñoz A. Control of metabolism and signaling of simple bioactive sphingolipids: Implications in disease. Prog Lipid Res 2010; 49:316-34. [PMID: 20193711 DOI: 10.1016/j.plipres.2010.02.004] [Citation(s) in RCA: 108] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2010] [Revised: 02/18/2010] [Accepted: 02/22/2010] [Indexed: 01/05/2023]
Abstract
Simple bioactive sphingolipids include ceramide, sphingosine and their phosphorylated forms sphingosine 1-phosphate and ceramide 1-phosphate. These molecules are crucial regulators of cell functions. In particular, they play important roles in the regulation of angiogenesis, apoptosis, cell proliferation, differentiation, migration, and inflammation. Decoding the mechanisms by which these cellular functions are regulated requires detailed understanding of the signaling pathways that are implicated in these processes. Most importantly, the development of inhibitors of the enzymes involved in their metabolism may be crucial for establishing new therapeutic strategies for treatment of disease.
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Affiliation(s)
- Patricia Gangoiti
- Department of Biochemistry and Molecular Biology, Faculty of Science and Technology, University of the Basque Country (UPV/EHU), Bilbao, Spain
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54
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Pua TL, Wang FQ, Fishman DA. Roles of LPA in ovarian cancer development and progression. Future Oncol 2010; 5:1659-73. [PMID: 20001802 DOI: 10.2217/fon.09.120] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Lysophosphatidic acid (LPA), a bioactive phospholipid, stimulates survival, proliferation, adhesion, migration and invasion of ovarian cancer cells through the activation of G-protein-coupled plasma membrane receptors. LPA and its receptors are aberrantly expressed in ovarian cancer, with high levels predominantly found in malignant ascites and in the plasma of ovarian cancer patients. LPA signals multiple intracellular pathways, such as Ras/MEKK1-MAPK and PI3K/Akt, to promote growth factors and protease expression, and induce angiogenesis and tumor cell invasion through the extracellular matrix and across the basement membrane. Only a small portion of this intricate lipid-signaling cascade has been characterized thus far. We believe that elucidation of this complex transduction network will provide further opportunities to understand the mechanism of ovarian carcinogenesis, invasion and metastasis.
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Affiliation(s)
- Tarah L Pua
- Gynecologic Oncology, New York University School of Medicine, New York, NY, USA
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55
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Ikeda H, Ohkawa R, Watanabe N, Nakamura K, Kume Y, Nakagawa H, Yoshida H, Okubo S, Yokota H, Tomiya T, Inoue Y, Nishikawa T, Ohtomo N, Tanoue Y, Koike K, Yatomi Y. Plasma concentration of bioactive lipid mediator sphingosine 1-phosphate is reduced in patients with chronic hepatitis C. Clin Chim Acta 2010; 411:765-70. [PMID: 20188085 DOI: 10.1016/j.cca.2010.02.063] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2009] [Revised: 02/17/2010] [Accepted: 02/18/2010] [Indexed: 10/19/2022]
Abstract
BACKGROUND Bioactive lipid mediator S1P has been suggested to play pathophysiological roles in various fields of clinical science as a circulating paracrine mediator. We previously established a reliable method of measuring plasma S1P concentration, and reported that the one in healthy subjects has a gender difference and a correlation with red blood cell (RBC)-parameters, however, the reports of S1P measurements in the blood in patients with a specific disease have been scarce. Because our previous evidence suggests that S1P is involved in liver pathophysiology, we examined plasma S1P concentration in chronic hepatitis C patients. METHODS S1P assay was performed using a high-performance liquid chromatography system. RESULTS Plasma S1P concentrations were reduced in chronic hepatitis C patients compared with in healthy subjects with the same hemoglobin concentration, irrespective of gender. Among the blood parameters, serum hyaluronic acid concentration, a surrogate marker for liver fibrosis, was most closely and inversely correlated with plasma S1P concentration. Furthermore, plasma S1P concentration decreased throughout the progression of carbon tetrachloride-induced liver fibrosis in rats. CONCLUSIONS Plasma S1P concentration was reduced in chronic hepatitis C patients, and liver fibrosis might be involved, at least in part, in the mechanism responsible for this reduction.
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Affiliation(s)
- Hitoshi Ikeda
- Department of Clinical Laboratory Medicine, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8655, Japan.
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56
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Labriola JM, daCosta CJB, Wang S, Figeys D, Smith JC, Sturgeon RM, Baenziger JE. Phospholipase C activity affinity purifies with the Torpedo nicotinic acetylcholine receptor. J Biol Chem 2010; 285:10337-43. [PMID: 20133947 DOI: 10.1074/jbc.m109.071993] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Nicotinic acetylcholine receptors mediate fast synaptic transmission by fluxing ions across the membrane in response to neurotransmitter binding. We show here that during affinity purification of the nicotinic acetylcholine receptor from Torpedo, phosphatidic acid, but not other anionic or zwitterionic phospholipids, is hydrolyzed to diacylglycerol. The phospholipase C activity elutes with the acetylcholine receptor and is inhibited by a lipid phosphate phosphohydrolase inhibitor, sodium vanadate, but not a phosphatidate phosphohydrolase inhibitor, N-ethylmaleimide. Further, the hydrolysis product of phosphatidic acid, diacylglycerol, enhances the functional capabilities of the acetylcholine receptor in the presence of anionic lipids. We conclude that a phospholipase C activity, which appears to be specific for phosphatidic acid, is associated with the nicotinic acetylcholine receptor. The acetylcholine receptor may directly or indirectly influence lipid metabolism in a manner that enhances its own function.
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Affiliation(s)
- Jonathan M Labriola
- Department of Biochemistry, Microbiology, and Immunology, University of Ottawa, Ottawa, Ontario K1H 8M5, Canada
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57
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Gómez-Muñoz A, Gangoiti P, Granado MH, Arana L, Ouro A. Ceramide-1-Phosphate in Cell Survival and Inflammatory Signaling. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2010; 688:118-30. [DOI: 10.1007/978-1-4419-6741-1_8] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
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58
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Suppression of cardiac phosphatidate phosphohydrolase 1 activity and lipin mRNA expression in Zucker diabetic fatty rats and humans with type 2 diabetes mellitus. Biochem Biophys Res Commun 2009; 390:165-70. [DOI: 10.1016/j.bbrc.2009.09.108] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2009] [Accepted: 09/24/2009] [Indexed: 11/20/2022]
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59
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Haller JF, Smith C, Liu D, Zheng H, Tornheim K, Han GS, Carman GM, Zoeller RA. Isolation of novel animal cell lines defective in glycerolipid biosynthesis reveals mutations in glucose-6-phosphate isomerase. J Biol Chem 2009; 285:866-77. [PMID: 19903819 DOI: 10.1074/jbc.m109.068213] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Glycerolipids are structural components for membranes and serve in energy storage. We describe here the use of a photodynamic selection technique to generate a population of Chinese hamster ovary cells that display a global deficiency in glycerolipid biosynthesis. One isolate from this population, GroD1, displayed a profound reduction in the synthesis of phosphatidylcholine, phosphatidylethanolamine, and triglycerides but presented high levels of phosphatidic acid and normal levels of phosphatidylinositol synthesis. This was accompanied by a reduction in phosphatidate phosphatase 1 (PAP1) activity. Expression cloning and sequencing of the cDNA obtained from GroD1 revealed a point mutation, Gly-189 --> Glu, in glucose-6-phosphate isomerase (GPI), a glycolytic enzyme involved in an inherited disorder that results in anemia and neuromuscular symptoms in humans. GPI activity was reduced by 87% in GroD1. No significant differences were found in DNA synthesis, protein synthesis, and ATP levels, whereas glycerol 3-phosphate levels were increased in the mutant. Expression of wild-type hamster GPI restored GPI activity, glycerolipid biosynthesis, and PAP1 activity in GroD1. Two additional, independently isolated GPI-deficient mutants displayed similar phenotypes with respect to PAP1 activity and glycerolipid biosynthesis. These findings uncover a novel relationship between GPI, involved in carbohydrate metabolism, and PAP1, a lipogenic enzyme. These results may also help to explain neuromuscular symptoms associated with inherited GPI deficiency.
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Affiliation(s)
- Jorge F Haller
- Department of Physiology and Biophysics, Boston University School of Medicine, Massachusetts 02118, USA
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60
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Giusto NM, Pasquaré SJ, Salvador GA, Ilincheta de Boschero MG. Lipid second messengers and related enzymes in vertebrate rod outer segments. J Lipid Res 2009; 51:685-700. [PMID: 19828910 DOI: 10.1194/jlr.r001891] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Rod outer segments (ROSs) are specialized light-sensitive organelles in vertebrate photoreceptor cells. Lipids in ROS are of considerable importance, not only in providing an adequate environment for efficient phototransduction, but also in originating the second messengers involved in signal transduction. ROSs have the ability to adapt the sensitivity and speed of their responses to ever-changing conditions of ambient illumination. A major contributor to this adaptation is the light-driven translocation of key signaling proteins into and out of ROS. The present review shows how generation of the second lipid messengers from phosphatidylcholine, phosphatidic acid, and diacylglycerol is modulated by the different illumination states in the vertebrate retina. Findings suggest that the light-induced translocation of phototransduction proteins influences the enzymatic activities of phospholipase D, lipid phosphate phosphatase, diacylglyceride lipase, and diacylglyceride kinase, all of which are responsible for the generation of the second messenger molecules.
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Affiliation(s)
- Norma M Giusto
- Instituto de Investigaciones Bioquímicas de Bahía Blanca, Universidad Nacional del Sur and Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Bahía Blanca, Argentina.
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61
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Trimbuch T, Beed P, Vogt J, Schuchmann S, Maier N, Kintscher M, Breustedt J, Schuelke M, Streu N, Kieselmann O, Brunk I, Laube G, Strauss U, Battefeld A, Wende H, Birchmeier C, Wiese S, Sendtner M, Kawabe H, Kishimoto-Suga M, Brose N, Baumgart J, Geist B, Aoki J, Savaskan NE, Bräuer AU, Chun J, Ninnemann O, Schmitz D, Nitsch R. Synaptic PRG-1 modulates excitatory transmission via lipid phosphate-mediated signaling. Cell 2009; 138:1222-35. [PMID: 19766573 DOI: 10.1016/j.cell.2009.06.050] [Citation(s) in RCA: 107] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2008] [Revised: 04/30/2009] [Accepted: 06/19/2009] [Indexed: 11/27/2022]
Abstract
Plasticity related gene-1 (PRG-1) is a brain-specific membrane protein related to lipid phosphate phosphatases, which acts in the hippocampus specifically at the excitatory synapse terminating on glutamatergic neurons. Deletion of prg-1 in mice leads to epileptic seizures and augmentation of EPSCs, but not IPSCs. In utero electroporation of PRG-1 into deficient animals revealed that PRG-1 modulates excitation at the synaptic junction. Mutation of the extracellular domain of PRG-1 crucial for its interaction with lysophosphatidic acid (LPA) abolished the ability to prevent hyperexcitability. As LPA application in vitro induced hyperexcitability in wild-type but not in LPA(2) receptor-deficient animals, and uptake of phospholipids is reduced in PRG-1-deficient neurons, we assessed PRG-1/LPA(2) receptor-deficient animals, and found that the pathophysiology observed in the PRG-1-deficient mice was fully reverted. Thus, we propose PRG-1 as an important player in the modulatory control of hippocampal excitability dependent on presynaptic LPA(2) receptor signaling.
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Affiliation(s)
- Thorsten Trimbuch
- Institute of Cell Biology and Neurobiology and NeuroCure, Charité, Universitätsmedizin Berlin, Berlin, Germany
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62
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Lindfors E, Gopalacharyulu PV, Halperin E, Orešič M. Detection of molecular paths associated with insulitis and type 1 diabetes in non-obese diabetic mouse. PLoS One 2009; 4:e7323. [PMID: 19798418 PMCID: PMC2749452 DOI: 10.1371/journal.pone.0007323] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2009] [Accepted: 09/13/2009] [Indexed: 12/31/2022] Open
Abstract
Recent clinical evidence suggests important role of lipid and amino acid metabolism in early pre-autoimmune stages of type 1 diabetes pathogenesis. We study the molecular paths associated with the incidence of insulitis and type 1 diabetes in the Non-Obese Diabetic (NOD) mouse model using available gene expression data from the pancreatic tissue from young pre-diabetic mice. We apply a graph-theoretic approach by using a modified color coding algorithm to detect optimal molecular paths associated with specific phenotypes in an integrated biological network encompassing heterogeneous interaction data types. In agreement with our recent clinical findings, we identified a path downregulated in early insulitis involving dihydroxyacetone phosphate acyltransferase (DHAPAT), a key regulator of ether phospholipid synthesis. The pathway involving serine/threonine-protein phosphatase (PP2A), an upstream regulator of lipid metabolism and insulin secretion, was found upregulated in early insulitis. Our findings provide further evidence for an important role of lipid metabolism in early stages of type 1 diabetes pathogenesis, as well as suggest that such dysregulation of lipids and related increased oxidative stress can be tracked to beta cells.
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Affiliation(s)
- Erno Lindfors
- VTT Technical Research Centre of Finland, Espoo, Finland
| | | | - Eran Halperin
- International Computer Science Institute, Berkeley, California, United States of America
| | - Matej Orešič
- VTT Technical Research Centre of Finland, Espoo, Finland
- * E-mail:
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63
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Tanyi J, Rigó Jr. J. Lysophosphatidic acid as a potential target for treatment and molecular diagnosis of epithelial ovarian cancers. Orv Hetil 2009; 150:1109-18. [DOI: 10.1556/oh.2009.28631] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Az ováriumtumorok mortalitása a legmagasabb a nőgyógyászati tumorok között. Ez egyrészt a késői diagnózisnak, másrészt a hatásos terápia hiányának következménye. Az ováriumtumorok karcinogenezise és metasztázisképzése egy komplikált genetikai, molekuláris és biokémiai folyamatsor eredménye. A lizofoszfátsav (LPA) termelésének, receptorstátusának és szignáltranszdukciós útvonalának abnormalitása gyakran megtalálható az ováriumtumorokban, ami azt sejteti, hogy az LPA nagyon fontos szerepet játszik ennek a betegségnek a kialakulásában és patofiziológiájában. Így jogosan feltételezhetjük, hogy az LPA-szignálkaszkád számos célpontot szolgáltat a molekuláris kezelési módok kialakítására és jó példát mutat arra, hogyan lehet új diagnosztikus és terápiás módszereket kialakítani egyes betegségek ellen. Az LPA-t lebontó és termelő enzimcsaládoknak csak a közelmúltban történt felfedezése és a receptorspecifikus molekulák kifejlesztése új fejezetet nyithat e potenciálisan halálos betegség kezelésében. Ebben az összefoglaló tanulmányban ismertetjük, hogy a tumorsejtekben lévő LPA-t lebontó enzimek aktivitása csökkent, és ez hozzájárul a tumor progressziójához. Ugyanezen enzimek mesterségesen létrehozott, fokozott aktivitása csökkenti a tumorsejtek növekedését és elősegíti a fiziológiás viszonyok helyreállását. Bemutatjuk azokat az irodalmi adatokat, amelyek egyértelműen bizonyítják, hogy a lipidfoszfát-foszfatáz enzimek hatásukat a sejten kívüli LPA lebontásával érik el. Minthogy ez a lebontás extracellulárisan történik, ez megmagyarázza a „bystander-effect” előfordulását, amit szintén ismertetünk. Az LPA-lebontás és -termelés enzimjei, illetve az LPA-t kötő receptorok kitűnő célpontok új molekuláris terápia kidolgozására. A különböző LPA-izoformák és más lizofoszfolipidek szintváltozásainak korai detektálása segíthet a tumor korai diagnosztizálásában, illetve később a kezelés hatékonyságának követésében. A közelmúlt jelentős LPA-szignálkaszkáddal kapcsolatos kutatási eredményei azt sejtetik, hogy azok jelentős szerepet fognak játszani ennek a még mindig halálos betegségnek a kezelésében, de további kutatások szükségesek a részletek pontos megértéséhez.
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Affiliation(s)
- János Tanyi
- 1 University of Pennsylvania Health System Department of Gynecologic Oncology Philadelphia
| | - János Rigó Jr.
- 2 Semmelweis Egyetem, Általános Orvostudományi Kar I. Szülészeti és Nőgyógyászati Klinika Budapest Baross u. 27. 1088
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64
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Carlo T, Petasis NA, Levy BD. Activation of polyisoprenyl diphosphate phosphatase 1 remodels cellular presqualene diphosphate. Biochemistry 2009; 48:2997-3004. [PMID: 19220020 PMCID: PMC2765513 DOI: 10.1021/bi8020636] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Polyisoprenyl diphosphates play diverse and vital roles in cell function in health and disease. The counter-regulatory lipid signaling molecule, presqualene diphosphate (PSDP), is rapidly converted to its monophosphate form (PSMP) upon cell activation [Levy, B. D., Petasis, N. A., and Serhan, C. N. (1997) Nature 389, 985-990]. The first PSDP phosphatase was recently identified and named polyisoprenyl diphosphate phosphatase 1 (PDP1) [Fukunaga, K., et al. (2006) J. Biol. Chem. 281, 9490-9497]. Here, we present evidence that PDP1 displays properties of a lipid phosphate phosphatase/phosphotransferase with distinct substrate preference for PSDP. Cell activation with PMA increased PSDP phosphatase activity in a concentration-dependent manner, and Western analysis suggested that PDP1 is directly phosphorylated by protein kinase C. Cellular PSDP phosphatase activity was also induced by the receptor-mediated agonists insulin and TNF-alpha. To address PDP1's contribution to cellular PSDP phosphatase activity, HEK293 cells were established that stably expressed PDP1 siRNA, leading to a 60% decrease in the level of PDP1 RNA, and concomitant decreases in PDP1 protein and PMA-initiated PSDP phosphatase activity. HEK293 cells harboring the PDP1 siRNA construct also displayed a marked decrease in the extent of PMA-initiated conversion of cellular PSDP to PSMP. Together, these findings are the first to indicate that PDP1 is activated during cell responses to soluble stimuli to convert PSDP to PSMP. Moreover, they provide evidence that PDP1 can serve as a new checkpoint for polyisoprenyl phosphate remodeling during cell activation.
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Affiliation(s)
- Troy Carlo
- Pulmonary and Critical Care Medicine, Brigham and Women's Hospital and Harvard Medical School, 75 Francis Street, Boston, MA 02115
| | - Nicos A. Petasis
- Department of Chemistry, University of Southern California, 837 West 37th Street, Los Angeles, CA 90089
| | - Bruce D. Levy
- Pulmonary and Critical Care Medicine, Brigham and Women's Hospital and Harvard Medical School, 75 Francis Street, Boston, MA 02115
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65
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Brindley DN, Pilquil C, Sariahmetoglu M, Reue K. Phosphatidate degradation: phosphatidate phosphatases (lipins) and lipid phosphate phosphatases. Biochim Biophys Acta Mol Cell Biol Lipids 2009; 1791:956-61. [PMID: 19250975 DOI: 10.1016/j.bbalip.2009.02.007] [Citation(s) in RCA: 82] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2008] [Revised: 02/06/2009] [Accepted: 02/15/2009] [Indexed: 11/16/2022]
Abstract
Three lipid phosphate phosphatases (LPPs) regulate cell signaling by modifying the concentrations of a variety of lipid phosphates versus their dephosphorylated products. In particular, the LPPs are normally considered to regulate signaling by the phospholipase D (PLD) pathway by converting phosphatidate (PA) to diacylglycerol (DAG). LPP activities do modulate the accumulations of PA and DAG following PLD activation, but this could also involve an effect upstream of PLD activation. The active sites of the LPPs are on the exterior surface of plasma membranes, or on the luminal surface of internal membranes. Consequently, the actions of the LPPs in metabolizing PA formed by PLD1 or PLD2 should depend on the access of this substrate to the active site of the LPPs. Alternatively, PA generated on the cytosolic surface of membranes should be readily accessible to the family of specific phosphatidate phosphatases, namely the lipins. Presently, there is only indirect evidence for the lipins participating in cell signaling following PLD activation. So far, we know relatively little about how individual LPPs and specific phosphatidate phosphatases (lipins) modulate cell signaling through controlling the turnover of bioactive lipids that are formed after PLD activation.
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Affiliation(s)
- David N Brindley
- Signal Transduction Research Group, Department of Biochemistry, University of Alberta, Alberta, Canada.
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66
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Cortés VA, Curtis DE, Sukumaran S, Shao X, Parameswara V, Rashid S, Smith AR, Ren J, Esser V, Hammer RE, Agarwal AK, Horton JD, Garg A. Molecular mechanisms of hepatic steatosis and insulin resistance in the AGPAT2-deficient mouse model of congenital generalized lipodystrophy. Cell Metab 2009; 9:165-76. [PMID: 19187773 PMCID: PMC2673980 DOI: 10.1016/j.cmet.2009.01.002] [Citation(s) in RCA: 178] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/22/2007] [Revised: 07/07/2008] [Accepted: 01/12/2009] [Indexed: 01/02/2023]
Abstract
Mutations in 1-acylglycerol-3-phosphate-O-acyltransferase 2 (AGPAT2) cause congenital generalized lipodystrophy. To understand the molecular mechanisms underlying the metabolic complications associated with AGPAT2 deficiency, Agpat2 null mice were generated. Agpat2(-/-) mice develop severe lipodystrophy affecting both white and brown adipose tissue, extreme insulin resistance, diabetes, and hepatic steatosis. The expression of lipogenic genes and rates of de novo fatty acid biosynthesis were increased approximately 4-fold in Agpat2(-/-) mouse livers. The mRNA and protein levels of monoacylglycerol acyltransferase isoform 1 were markedly increased in the livers of Agpat2(-/-) mice, suggesting that the alternative monoacylglycerol pathway for triglyceride biosynthesis is activated in the absence of AGPAT2. Feeding a fat-free diet reduced liver triglycerides by approximately 50% in Agpat2(-/-) mice. These observations suggest that both dietary fat and hepatic triglyceride biosynthesis via a monoacylglycerol pathway may contribute to hepatic steatosis in Agpat2(-/-) mice.
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Affiliation(s)
- Víctor A Cortés
- Department of Molecular Genetics, University of Texas Southwestern Medical Center at Dallas, Dallas, TX 75390, USA
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67
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Abstract
Lipid phosphate phosphatases (LPPs) regulate cell signaling by modifying the concentrations of lipid phosphates versus their dephosphorylated products. The ecto-activity regulates the availability of extracellular lysophosphatidate (LPA) and sphingosine 1-phosphate (S1P) and thereby signaling by their respective receptors. LPP products (monoacylglycerol or sphingosine) are taken up by cells and rephosphorylated to produce LPA and S1P, respectively, which activate intracellular signaling cascades. The proposed integrin binding domain on the external surface of LPP3 modifies cell/cell interactions. Expression of LPPs on internal membranes controls signaling depending on the access of lipid phosphates to their active sites. Different LPPs perform distinct functions, probably based on integrin binding, their locations, and their abilities to metabolize different lipid phosphates in vivo.
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Affiliation(s)
- David N Brindley
- Signal Transduction Research Group, Department of Biochemistry, University of Alberta, Edmonton, Alberta, T6G 2S2, Canada.
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68
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França MGC, Matos AR, D'arcy-Lameta A, Passaquet C, Lichtlé C, Zuily-Fodil Y, Pham-Thi AT. Cloning and characterization of drought-stimulated phosphatidic acid phosphatase genes from Vigna unguiculata. PLANT PHYSIOLOGY AND BIOCHEMISTRY : PPB 2008; 46:1093-100. [PMID: 18755595 DOI: 10.1016/j.plaphy.2008.07.004] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/14/2007] [Revised: 06/14/2008] [Accepted: 07/09/2008] [Indexed: 05/22/2023]
Abstract
Under environmental stresses, several lipolytic enzymes are known to be activated and to contribute to membrane lipid turnover and generation of second messengers. In animal cells, phosphatidic acid phosphatase (PAP, EC 3.1.3.4), which dephosphorylates phosphatidic acid generating diacylglycerol, is long known as an enzyme involved in lipid synthesis and cell signalling. However, knowledge on PAP in plants remains very limited. The aim of this work was to isolate and characterize PAP genes in the tropical legume Vigna unguiculata (cowpea), and to study their expression under different stress conditions. Two cDNAs designated as VuPAPalpha and VuPAPbeta were cloned from the leaves of cowpea. Both proteins share sequence homology to animal type 2 PAP, namely, the six transmembrane regions and the consensus sequences corresponding to the catalytic domain of the phosphatase family, like the recently described Arabidopsis LPP (Lipid Phosphate Phosphatase) proteins. The recombinant protein VuPAPalpha expressed in Escherichia coli cells was able to convert phosphatidic acid into diacylglycerol. Unlike VuPAPbeta, VuPAPalpha has an N-terminal transit peptide and was addressed to chloroplast in vitro. Both genes are expressed in several cowpea organs and their transcripts accumulate in leaves in response to water deficit, including progressive dehydration of whole plants and rapid desiccation of detached leaves. No changes in expression of both genes were observed after wounding or by treatment with jasmonic acid. Furthermore, the in silico analysis of VuPAPalpha promoter allowed the identification of several putative drought-related regulatory elements. The possible physiological role of the two cloned PAPs is discussed.
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Affiliation(s)
- Marcel Giovanni Costa França
- Departamento de Botânica, Universidade Federal de Minas Gerais, ICB, Av. Antônio Carlos 6627, Pampulha, 31270-901 Belo Horizonte, MG, Brazil
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69
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Karbarz MJ, Six DA, Raetz CRH. Purification and characterization of the lipid A 1-phosphatase LpxE of Rhizobium leguminosarum. J Biol Chem 2008; 284:414-425. [PMID: 18984595 DOI: 10.1074/jbc.m808390200] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
LpxE, a membrane-bound phosphatase found in Rhizobium leguminosarum and some other Gram-negative bacteria, selectively dephosphorylates the 1-position of lipid A on the outer surface of the inner membrane. LpxE belongs to the family of lipid phosphate phosphatases that contain a tripartite active site motif and six predicted transmembrane helices. Here we report the purification and characterization of R. leguminosarum LpxE. A modified lpxE gene, encoding a protein with an N-terminal His6 tag, was expressed in Escherichia coli. The protein was solubilized with Triton X-100 and purified to near-homogeneity. Gel electrophoresis reveals a molecular weight consistent with the predicted 31 kDa. LpxE activity is dependent upon Triton X-100, optimal near pH 6.5, and Mg2+-independent. The H197A and R133A substitutions inactivate LpxE, as does treatment with diethyl pyrocarbonate. In a mixed micelle assay system, the apparent Km for the precursor lipid IV(A) is 11 microm. Substrates containing the 3-deoxy-d-manno-oct-2-ulosonic acid disaccharide are dephosphorylated at similar rates to lipid IV(A), whereas glycerophospholipids like phosphatidic acid or phosphatidylglycerol phosphate are very poor substrates. However, an LpxE homologue present in Agrobacterium tumefaciens is selective for phosphatidylglycerol phosphate, demonstrating the importance of determining substrate specificity before assigning the functions of LpxE-related proteins. The availability of purified LpxE will facilitate the preparation of novel 1-dephosphorylated lipid A molecules that are not readily accessible by chemical methods.
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Affiliation(s)
- Mark J Karbarz
- Department of Biochemistry, Duke University Medical Center, Durham, North Carolina 27710
| | - David A Six
- Department of Biochemistry, Duke University Medical Center, Durham, North Carolina 27710
| | - Christian R H Raetz
- Department of Biochemistry, Duke University Medical Center, Durham, North Carolina 27710.
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70
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Theofilopoulos S, Lykidis A, Leondaritis G, Mangoura D. Novel function of the human presqualene diphosphate phosphatase as a type II phosphatidate phosphatase in phosphatidylcholine and triacylglyceride biosynthesis pathways. Biochim Biophys Acta Mol Cell Biol Lipids 2008; 1781:731-42. [DOI: 10.1016/j.bbalip.2008.09.001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2008] [Revised: 08/29/2008] [Accepted: 09/11/2008] [Indexed: 11/27/2022]
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71
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Racagni G, Villasuso AL, Pasquaré SJ, Giusto NM, Machado E. Diacylglycerol pyrophosphate inhibits the alpha-amylase secretion stimulated by gibberellic acid in barley aleurone. PHYSIOLOGIA PLANTARUM 2008; 134:381-93. [PMID: 18573189 DOI: 10.1111/j.1399-3054.2008.01148.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
ABA plays an important regulatory role in seed germination because it inhibits the response to GA in aleurone, a secretory tissue surrounding the endosperm. Phosphatidic acid (PA) is a well-known intermediary in ABA signaling, but the role of diacylglycerol pyrophosphate (DGPP) in germination processes is not clearly established. In this study, we show that PA produced by phospholipase D (E.C. 3.1.4.4) during the antagonist effect of ABA in GA signaling is rapidly phosphorylated by phosphatidate kinase (PAK) to DGPP. This is a crucial fact for aleurone function because exogenously added dioleoyl-DGPP inhibits secretion of alpha-amylase (E.C. 3.2.1.1). Aleurone treatment with ABA and 1-butanol results in normal secretory activity, and this effect is reversed by addition of dioleoyl-DGPP. We also found that ABA decreased the activity of an Mg2+-independent, N-ethylmaleimide-insensitive form of phosphatidate phosphohydrolase (PAP2) (E.C. 3.1.3.4), leading to reduction of PA dephosphorylation and increased PAK activity. Sequence analysis using Arabidopsis thaliana lipid phosphate phosphatase (LPP) sequences as queries identified two putative molecular homologues, termed HvLPP1 and HvLPP2, encoding putative Lpps with the presence of well-conserved structural Lpp domains. Our results are consistent with a role of DGPP as a regulator of ABA antagonist effect in GA signaling and provide evidence about regulation of PA level by a PAP2 during ABA response in aleurone.
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Affiliation(s)
- Graciela Racagni
- Química Biológica, FCEFQN, Universidad Nacional de Río Cuarto, X5804BYA Río Cuarto, Córdoba, Argentina
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72
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KIHARA A. Production and release of sphingosine 1-phosphate and the phosphorylated form of the immunomodulator FTY720. Biochim Biophys Acta Mol Cell Biol Lipids 2008; 1781:496-502. [DOI: 10.1016/j.bbalip.2008.05.003] [Citation(s) in RCA: 70] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2007] [Revised: 05/16/2008] [Accepted: 05/16/2008] [Indexed: 11/26/2022]
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73
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Lipid phosphate phosphatases form homo- and hetero-oligomers: catalytic competency, subcellular distribution and function. Biochem J 2008; 411:371-7. [PMID: 18215144 DOI: 10.1042/bj20071607] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Lipid phosphate phosphatases (LPP1-LPP3) have been topographically modelled as monomers (molecular mass of 31-36 kDa) composed of six transmembrane domains and with the catalytic site facing the extracellular side of the plasma membrane or the luminal side of intracellular membranes. The catalytic motif has three conserved domains, termed C1, C2 and C3. The C1 domain may be involved in substrate recognition, whereas C2 and C3 domains appear to participate in the catalytic dephosphorylation of the substrate. We have obtained three lines of evidence to demonstrate that LPPs exist as functional oligomers. First, we have used recombinant expression and immunoprecipitation analysis to demonstrate that LPP1, LPP2 and LPP3 form both homo- and hetero-oligomers. Secondly, large LPP oligomeric complexes that are catalytically active were isolated using gel-exclusion chromatography. Thirdly, we demonstrate that catalytically deficient guinea-pig FLAG-tagged H223L LPP1 mutant can form an oligomer with wild-type LPP1 and that wild-type LPP1 activity is preserved in the oligomer. These findings suggest that, in an oligomeric arrangement, the catalytic site of the wild-type LPP can function independently of the catalytic site of the mutant LPP. Finally, we demonstrate that endogenous LPP2 and LPP3 form homo- and hetero-oligomers, which differ in their subcellular localization and which may confer differing spatial regulation of phosphatidic acid and sphingosine 1-phosphate signalling.
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74
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Pasquaré SJ, Salvador GA, Giusto NM. Involvement of Lysophosphatidic Acid, Sphingosine 1-Phosphate and Ceramide 1-Phosphate in the Metabolization of Phosphatidic Acid by Lipid Phosphate Phosphatases in Bovine Rod Outer Segments. Neurochem Res 2008; 33:1205-15. [DOI: 10.1007/s11064-007-9569-5] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2007] [Accepted: 12/12/2007] [Indexed: 12/29/2022]
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75
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Avendaño-Vázquez SE, Cabrera-Wrooman A, Colín-Santana CC, García-Sáinz JA. Lysophosphatidic acid LPA1 receptor close-up. ACTA ACUST UNITED AC 2007. [DOI: 10.1002/sita.200700138] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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76
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Burgdorf C, Prey A, Richardt G, Kurz T. A HPLC-fluorescence detection method for determination of phosphatidic acid phosphohydrolase activity: application in human myocardium. Anal Biochem 2007; 374:291-7. [PMID: 18023403 DOI: 10.1016/j.ab.2007.10.039] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2007] [Revised: 10/15/2007] [Accepted: 10/30/2007] [Indexed: 11/13/2022]
Abstract
Phosphatidic acid phosphohydrolase (PAP) catalyzes the dephosphorylation of phosphatidic acid (PA) to diacylglycerol, the second messenger responsible for activation of protein kinase C. Despite the crucial role of PAP lipid signaling, there are no data on PAP signaling function in the human heart. Here we present a nonradioactive assay for the investigation of PAP activity in human myocardium using a fluorescent derivative of PA, 2-(4,4-difluoro-5,7-dimethyl-4-bora-3a,4a-diaza-s-indacene-3-pentanoyl)-1-hexadecanoyl-sn-glycero-3-phosphate (BODIPY-PA), as substrate in an in vitro PAP-catalyzed reaction. Unreacted BODIPY-PA was resolved from the PAP products by a binary gradient HPLC system and BODIPY-diacylglycerol was detected by fluorimetry. The reaction proceeded at a linear rate for up to 60 min and increased linearly with increasing amounts of cardiac protein in a range of 0.25 to 8.0 microg. This assay proved to be sensitive for accurate quantitation of total PAP activity, PAP-1 activity, and PAP-2 activity in human atrial tissue and right ventricular endomyocardial biopsies. Total PAP activity was approximately fourfold higher in ventricular myocardium than in atrial tissue. There was negligible PAP-1 activity in atrial myocardium compared with ventricular myocardium, indicating regional differences in activities and distribution pattern of PAP-1 and PAP-2 in the human heart.
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Affiliation(s)
- Christof Burgdorf
- Medizinische Klinik II, Universitätsklinikum Schleswig-Holstein, 23538 Lübeck, Germany.
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77
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Escalante-Alcalde D, Sánchez-Sánchez R, Stewart CL. Generation of a conditional Ppap2b/Lpp3 null allele. Genesis 2007; 45:465-9. [PMID: 17610274 DOI: 10.1002/dvg.20314] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Lpp3, formerly known as Pap2b, is a lipid phosphohydrolase enzyme. Some of its substrates and products are lipids with potent biological and signaling activities such as phosphatidic acid, lysophosphatidic acid, sphingosine-1-phosphate, diacylglycerol, sphingosine, and ceramide. Lpp3 is dynamically expressed during development and is widely distributed in adult tissues. Targeted inactivation of Lpp3 gene (Ppap2b) in the mouse results in embryonic lethality because of defects in extraembryonic vascular development and gastrulation. To study the participation of Lpp3 later in development and in specific cell lineages we generated a conditional allele of Ppap2b. This was accomplished by flanking critical exons, responsible for its catalytic activity with loxP sites. A generalized Cre-mediated recombination of this allele yielded a phenotype fundamentally identical to our previously reported Ppap2b null allele.
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Affiliation(s)
- Diana Escalante-Alcalde
- Cancer and Developmental Biology Laboratory, Center for Cancer Research, National Cancer Institute, Frederick, Maryland, USA
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78
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Watanabe N, Ikeda H, Nakamura K, Ohkawa R, Kume Y, Aoki J, Hama K, Okudaira S, Tanaka M, Tomiya T, Yanase M, Tejima K, Nishikawa T, Arai M, Arai H, Omata M, Fujiwara K, Yatomi Y. Both plasma lysophosphatidic acid and serum autotaxin levels are increased in chronic hepatitis C. J Clin Gastroenterol 2007; 41:616-23. [PMID: 17577119 DOI: 10.1097/01.mcg.0000225642.90898.0e] [Citation(s) in RCA: 150] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
OBJECTIVES Recent accumulating evidence indicates that lysophosphatidic acid (LPA) is a lipid mediator, abundantly present in blood, with a wide range of biologic actions including the regulation of proliferation and contraction in liver cells. Although it is speculated that LPA might play a role in pathophysiologic processes in vivo, not only its role but also even a possible alteration in its blood concentration under specific diseases is essentially unknown. Autotaxin (ATX), originally purified as an autocrine motility factor for melanoma cells, was revealed to be a key enzyme in LPA synthesis. We determined LPA and ATX levels in the blood of patients with liver disease. METHODS ATX activity was measured by determining choline with the substrate of lysophosphatidylcholine, and the LPA level by an enzymatic cycling method in 41 patients with chronic hepatitis C. RESULTS The serum ATX activity and plasma LPA level were significantly increased in patients, and were correlated positively with serum hyaluronic acid, and negatively with platelets, albumin, and prothrombin time. The plasma LPA level was strongly correlated with serum ATX activity. There were significant correlations between the histologic stage of fibrosis and both the serum ATX activity and plasma LPA level. CONCLUSIONS The serum ATX activity and plasma LPA level are increased in chronic hepatitis C in association with liver fibrosis. Our study may provide the first evidence showing a significant increase of both ATX and LPA in the blood under a specific disease.
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Affiliation(s)
- Naoko Watanabe
- Department of Gastroenterology, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8655, Japan
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79
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Takeuchi M, Harigai M, Momohara S, Ball E, Abe J, Furuichi K, Kamatani N. Cloning and characterization of DPPL1 and DPPL2, representatives of a novel type of mammalian phosphatidate phosphatase. Gene 2007; 399:174-80. [PMID: 17590538 DOI: 10.1016/j.gene.2007.05.009] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2007] [Accepted: 05/15/2007] [Indexed: 11/22/2022]
Abstract
Phosphatidate phosphatase (PAP) enzymes are classified as either Mg(2+)-dependent (PAP1) or Mg(2+)-independent (PAP2) with respect to their Mg(2+) cofactor requirement for catalytic activity. Sensitivity to the thioreactive compound N-ethylmaleimide (NEM) has also been used to differentiate PAP1 (NEM-sensitive) from PAP2 (NEM-insensitive) activity in mammalian cells. We report here the cloning and initial characterization of DPPL1 and DPPL2, representatives of a novel type of mammalian phosphatidate phosphatase. Both DPPL1 and DPPL2 show greater homology to a yeast diacylglycerol pyrophosphate (DGPP) phosphatase, DPP1, than to known phosphatidate phosphatases of mammals. Like the yeast DPP1 protein, both DPPL1 and DPPL2 proteins show broad substrate specificity, but DGPP is the preferred substrate compared with LPA and PA. These reactions are Mg(2+)-independent, but unlike DPP1 and mammalian PAP2, they are sensitive to NEM. DPPL1 mRNA is ubiquitously expressed in various tissues and cells, but DPPL2 mRNA is restricted to several tissues including the brain, kidney and testis, and it is preferentially expressed in endothelial cells. Immunohistological staining of synovium containing vessels, plasma cells and lymphocytes revealed specific expression of DPPL2 protein in the endothelium. Collectively, our work indicates that DPPL1 and DPPL2 represent a novel type of mammalian phosphatidate phosphatase.
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Affiliation(s)
- Masahiro Takeuchi
- Institute of Rheumatology, Tokyo Women's Medical University, 10-22 Kawada-cho, Shinjuku, Tokyo, 162-0054, Japan.
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80
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Abstract
Mammalian phospholipase D (PLD), a signal transduction-activated enzyme, hydrolyzes phosphatidylcholine to generate the lipid second messenger phosphatidic acid (PA) and choline. Genetic and pharmacological methods have implicated PLD and its product PA in a wide variety of cellular processes including vesicle trafficking, receptor signaling, cell proliferation and survival. Dysregulation of these cell biologic processes occurs in a diverse range of illnesses including cancer. This review summarizes PLD regulation and function and highlights its potential as a therapeutic target in disease settings.
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Affiliation(s)
- Ping Huang
- University Medical Center at Stony Brook, Department of Pharmacology and the Center for Developmental Genetics, Stony Brook, NY 11794-5140, USA
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81
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Abstract
Phospholipid biosynthetic enzymes produce diverse molecular structures and are often present in multiple forms encoded by different genes. This work utilizes comparative genomics and phylogenetics for exploring the distribution, structure and evolution of phospholipid biosynthetic genes and pathways in 26 eukaryotic genomes. Although the basic structure of the pathways was formed early in eukaryotic evolution, the emerging picture indicates that individual enzyme families followed unique evolutionary courses. For example, choline and ethanolamine kinases and cytidylyltransferases emerged in ancestral eukaryotes, whereas, multiple forms of the corresponding phosphatidyltransferases evolved mainly in a lineage specific manner. Furthermore, several unicellular eukaryotes maintain bacterial-type enzymes and reactions for the synthesis of phosphatidylglycerol and cardiolipin. Also, base-exchange phosphatidylserine synthases are widespread and ancestral enzymes. The multiplicity of phospholipid biosynthetic enzymes has been largely generated by gene expansion in a lineage specific manner. Thus, these observations suggest that phospholipid biosynthesis has been an actively evolving system. Finally, comparative genomic analysis indicates the existence of novel phosphatidyltransferases and provides a candidate for the uncharacterized eukaryotic phosphatidylglycerol phosphate phosphatase.
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Affiliation(s)
- Athanasios Lykidis
- Genome Biology Program, DOE-Joint Genome Institute, Walnut Creek, CA 94598, USA.
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82
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Jeng YJ, Suarez VR, Izban MG, Wang HQ, Soloff MS. Progesterone-induced sphingosine kinase-1 expression in the rat uterus during pregnancy and signaling consequences. Am J Physiol Endocrinol Metab 2007; 292:E1110-21. [PMID: 17164439 DOI: 10.1152/ajpendo.00373.2006] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Sphingosine 1-phosphate (Sph-1-P), a product of sphingomyelin metabolism, can act via a family of cognate G protein-coupled receptors or as an intracellular second messenger for agonists acting through their membrane receptors. In view of the general growth promoting and developmental effects of Sph-1-P on target cells, we hypothesized that it plays a role in adaptation of the uterus to pregnancy. We analyzed its potential role and that of the related lysophospholipid lysophosphatidic acid in the pregnant rat uterus by examining changes in mRNA levels of cognate receptors and enzymes involved in their turnover. Of these, only sphingosine kinase-1 (SphK1) was markedly changed ( approximately 30-fold increase), being localized in the glandular epithelium, vasculature, and the myometrium. Uterine SphK1 mRNA and protein levels paralleled those of serum progesterone, and treatment with progesterone or an antagonist elevated or reduced SphK1 mRNA expression, respectively. Progesterone also increased SphK1 mRNA steady-state levels in a rat myometrial/leiomyoma cell line (ELT3). Overexpressing human SphK1 in these cells resulted in increased levels of the cell cycle regulator cyclin D1 and increased myosin light-chain phosphorylation. Ectopic expression of SphK1 also resulted in increased proliferation rates, possibly in conjunction with increased cyclin D1 expression. These studies suggest that the uterine expression of SphK1 mediates processes involved in growth and differentiation of uterine tissues during pregnancy.
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Affiliation(s)
- Yow-Jiun Jeng
- Department of Obstetrics and Gynecology, University of Texas Medical Branch, Galveston, TX 77555-1062, USA
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83
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Kihara A, Mitsutake S, Mizutani Y, Igarashi Y. Metabolism and biological functions of two phosphorylated sphingolipids, sphingosine 1-phosphate and ceramide 1-phosphate. Prog Lipid Res 2007; 46:126-44. [PMID: 17449104 DOI: 10.1016/j.plipres.2007.03.001] [Citation(s) in RCA: 121] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Sphingolipids are major lipid constituents of the eukaryotic plasma membrane. Without certain sphingolipids, cells and/or embryos cannot survive, indicating that sphingolipids possess important physiological functions that are not substituted for by other lipids. One such role may be signaling. Recent studies have revealed that some sphingolipid metabolites, such as long-chain bases (LCBs; sphingosine (Sph) in mammals), long-chain base 1-phosphates (LCBPs; sphingosine 1-phosphate (S1P) in mammals), ceramide (Cer), and ceramide 1-phosphate (C1P), act as signaling molecules. The addition of phosphate groups to LCB/Sph and Cer generates LCBP/S1P and C1P, respectively. These phospholipids exhibit completely different functions than those of their precursors. In this review, we describe recent advances in understanding the functions of LCBP/S1P and C1P in mammals and in the yeast Saccharomyces cerevisiae. Since LCB/Sph, LCBP/S1P, Cer, and C1P are mutually convertible, regulation of not only the total amount of the each lipid but also of the overall balance in cellular levels is important. Therefore, we describe in detail their metabolic pathways, as well as the genes involved in each reaction.
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Affiliation(s)
- Akio Kihara
- Laboratory of Biomembrane and Biofunctional Chemistry, Faculty of Pharmaceutical Sciences, Hokkaido University, Nishi 6-Choume, Sapporo, Japan.
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84
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Sigal YJ, Quintero OA, Cheney RE, Morris AJ. Cdc42 and ARP2/3-independent regulation of filopodia by an integral membrane lipid-phosphatase-related protein. J Cell Sci 2007; 120:340-52. [PMID: 17200142 DOI: 10.1242/jcs.03335] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
Filopodia are dynamic cell surface protrusions that are required for proper cellular development and function. We report that the integral membrane protein lipid-phosphatase-related protein 1 (LPR1) localizes to and promotes the formation of actin-rich, dynamic filopodia, both along the cell periphery and the dorsal cell surface. Regulation of filopodia by LPR1 was not mediated by cdc42 or Rif, and is independent of the Arp2/3 complex. We found that LPR1 can induce filopodia formation in the absence of the Ena/Vasp family of proteins, suggesting that these molecules are not essential for the development of the protrusions. Mutagenesis experiments identified residues and regions of LPR1 that are important for the induction of filopodia. RNA interference experiments in an ovarian epithelial cancer cell line demonstrated a role for LPR1 in the maintenance of filopodia-like membrane protrusions. These observations, and our finding that LPR1 is a not an active lipid phosphatase, suggest that LPR1 may be a novel integral membrane protein link between the actin core and the surrounding lipid layer of a nascent filopodium.
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Affiliation(s)
- Yury J Sigal
- Department of Cell and Developmental Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-7090, USA
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85
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Maceyka M, Milstien S, Spiegel S. Measurement of mammalian sphingosine-1-phosphate phosphohydrolase activity in vitro and in vivo. Methods Enzymol 2007; 434:243-56. [PMID: 17954251 DOI: 10.1016/s0076-6879(07)34013-5] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Sphingolipid metabolites have emerged as key players in diverse processes including cell migration, growth, and apoptosis. Ceramide and sphingosine typically inhibit cell growth and induce apoptosis, while sphingosine-1-phosphate (S1P) promotes cell growth, inhibits apoptosis, and induces cell migration. Thus, enzymes that regulate the levels of these sphingolipid metabolites are of critical importance to understanding cell fate. There are two known mammalian isoforms of S1P phosphohydrolases (SPP1 and SPP2) that reversibly degrade S1P to sphingosine. This chapter discusses the importance of SPPs and describes assays that can be used to measure the activity of these two specific S1P phosphohydrolases in cells and cell lysates.
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Affiliation(s)
- Michael Maceyka
- Department of Biochemistry and Molecular Biology, Virginia Commonwealth University School of Medicine, Richmond, Virginia, USA
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86
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Abstract
In the trans-Golgi network (TGN), proteins are sorted for transport to the endosomes, plasma membrane, preceding Golgi cisternae, and endoplasmic reticulum. The formation of clathrin-coated vesicles for transport to the endosomes and of COP-I-coated vesicles for retrograde trafficking is fairly well characterized at the molecular level. We describe our current understanding of the TGN-to-cell-surface carriers, with a specific focus on the components involved in membrane fission. Inhibiting the fission machinery promotes growth of transport carriers into large tubules that remain attached to the TGN. Overactivating this machinery, on the other hand, vesiculates the TGN. To understand how membrane fission is regulated by cargo to form transport carriers yet prevents complete vesiculation of the TGN remains a daunting challenge. We discuss these issues with regard to TGN-to-cell-surface transport carriers.
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Affiliation(s)
- Frédéric Bard
- Cell and Developmental Biology Department, University of California San Diego, La Jolla, California 92093, USA.
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87
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Donkor J, Sariahmetoglu M, Dewald J, Brindley DN, Reue K. Three mammalian lipins act as phosphatidate phosphatases with distinct tissue expression patterns. J Biol Chem 2006; 282:3450-7. [PMID: 17158099 DOI: 10.1074/jbc.m610745200] [Citation(s) in RCA: 288] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
We previously identified mutations in the Lpin1 gene, encoding lipin-1, as the underlying cause of lipodystrophy in the fatty liver dystrophy (fld) mutant mouse. Lipin-1 is normally expressed at high levels in adipose tissue and skeletal muscle, and deficiency in the fld mouse causes impaired adipose tissue development, insulin resistance, and altered energy expenditure. We also identified two additional lipin protein family members of unknown function, lipin-2 and lipin-3. Han et al. (Han, G. S., Wu, W. I., and Carman, G. M. (2006) J. Biol. Chem. 281, 9210-9218) recently demonstrated that the single lipin homolog in yeast, Smp2, exhibits phosphatidate phosphatase type-1 (PAP1) activity, which has a key role in glycerolipid synthesis. Here we demonstrate that lipin-1 accounts for all of the PAP1 activity in white and brown adipose tissue and skeletal muscle. However, livers of lipin-1-deficient mice exhibited normal PAP1 activity, indicating that other members of the lipin protein family could have PAP1 activity. Consistent with this possibility, recombinant lipin-2 and lipin-3 possess PAP1 activity. Each of the three lipin family members showed Mg2+-dependent activity that was specific for phosphatidate under the conditions employed. The different lipins showed distinct tissue expression patterns. Our results establish the three mammalian lipin proteins as PAP1 enzymes and explain the biochemical basis for lipodystrophy in the lipin-1-deficient fld mouse.
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Affiliation(s)
- Jimmy Donkor
- Department of Human Genetics and Medicine, David Geffen School of Medicine, University of California, Los Angeles, California 90095, USA
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88
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Kai M, Sakane F, Jia YJ, Imai SI, Yasuda S, Kanoh H. Lipid Phosphate Phosphatases 1 and 3 Are Localized in Distinct Lipid Rafts. ACTA ACUST UNITED AC 2006; 140:677-86. [PMID: 17005594 DOI: 10.1093/jb/mvj195] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Lipid phosphate phosphatases (LPPs), integral membrane proteins with six transmembrane domains, dephosphorylate a variety of extracellular lipid phosphates. Although LPP3 is already known to bind to Triton X-100-insoluble rafts, we here report that LPP1 is also associated with lipid rafts distinct from those harboring LPP3. We found that LPP1 was Triton X-100-soluble, but CHAPS-insoluble in LNCaP cells endogenously expressing LPP1 and several LPP1 cDNA-transfected cells including NIH3T3 fibroblasts. In addition to the non-ionic detergent insolubility, LPP1 further possessed several properties formulated for raft-localizing proteins as follows: first, the CHAPS-insolubility was resistant to the actin-disrupting drug cytochalasin D; second, the CHAPS-insoluble LPP1 floated in an Optiprep density gradient; third, the CHAPS insolubility of LPP1 was lost by cholesterol depletion; and finally, the subcellular distribution pattern of LPP1 exclusively overlapped with that of a raft marker, cholera toxin B subunit. Interestingly, confocal microscopic analysis showed that LPP1 was distributed to membrane compartments distinct from those of LPP3. Analysis using various LPP1/LPP3 chimeras revealed that their first extracellular regions determine the different Triton X-100 solubilities. These results indicate that LPP1 and LPP3 are distributed in distinct lipid rafts that may provide unique microenvironments defining their non-redundant physiological functions.
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Affiliation(s)
- Masahiro Kai
- Department of Biochemistry, Sapporo Medical University School of Medicine, West-17, South-1, Sapporo 060-8556
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89
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Carman GM, Han GS. Roles of phosphatidate phosphatase enzymes in lipid metabolism. Trends Biochem Sci 2006; 31:694-9. [PMID: 17079146 PMCID: PMC1769311 DOI: 10.1016/j.tibs.2006.10.003] [Citation(s) in RCA: 211] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2006] [Revised: 09/14/2006] [Accepted: 10/20/2006] [Indexed: 11/29/2022]
Abstract
Phosphatidate phosphatase (PAP) enzymes catalyze the dephosphorylation of phosphatidate, yielding diacylglycerol and inorganic phosphate. In eukaryotic cells, PAP activity has a central role in the synthesis of phospholipids and triacylglycerol through its product diacylglycerol, and it also generates and/or degrades lipid-signaling molecules that are related to phosphatidate. There are two types of PAP enzyme, Mg(2+) dependent (PAP1) and Mg(2+) independent (PAP2), but only genes encoding PAP2 enzymes had been identified until recently, when a gene (PAH1) encoding a PAP1 enzyme was found in Saccharomyces cerevisiae. This discovery has revealed a molecular function of the mammalian protein lipin, a deficiency of which causes lipodystrophy in mice. With molecular information now available for both types of PAP, the specific roles of these enzymes in lipid metabolism are being clarified.
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Affiliation(s)
- George M Carman
- Department of Food Science, Cook College, New Jersey Agricultural Experiment Station, Rutgers University, 65 Dudley Road, New Brunswick, NJ 08901, USA.
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90
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McDermott MI, Sigal YJ, Crump JS, Morris AJ. Enzymatic analysis of lipid phosphate phosphatases. Methods 2006; 39:169-79. [PMID: 16815033 DOI: 10.1016/j.ymeth.2006.05.010] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2006] [Accepted: 05/01/2006] [Indexed: 11/25/2022] Open
Abstract
Lipid phosphate monoesters including phosphatidic acid, lysophosphatidic acid, sphingosine 1-phosphate and ceramide 1-phosphate are intermediates in phosho- and sphingo-lipid biosynthesis and also play important roles in intra- and extra-cellular signaling. Dephosphorylation of these lipids terminates their signaling actions and, in some cases, generates products with additional biological activities or metabolic fates. The key enzymes responsible for dephosphorylation of these lipid phosphate substrates are collectively termed lipid phosphate phosphatases (LPPs). They are integral membrane enzymes with a core domain of six transmembrane spanning alpha-helices linked by extramembrane loops. LPPs are oriented in the membrane with their N- and C-termini facing the cytoplasm. LPPs exhibit isoform and cell specific localization patterns being variably distributed between endomembrane compartments (primarily the endoplasmic reticulum and Golgi apparatus) and the plasma membrane. The active site of these enzymes is formed from residues within two of the extramembrane loops and faces the lumen of endomembrane compartments or, when localized to the plasma membrane, towards, the extracellular space. Biochemical, pharmacological, cell biological and genetic studies identify roles for LPPs in both intracellular lipid metabolism and the regulation of both intra- and extra-cellular signaling pathways that control cell growth, survival and migration. This article describes procedures for the expression of LPPs in insect and mammalian cells and their analysis by SDS-PAGE and Western blotting. The most straightforward way to determine LPP activity is to measure release of the substrate phosphate group. We described methods for the synthesis and purification of [(32)P]-labeled LPP substrates. We describe the use of both radiolabeled and fluorescent lipid substrates for the detection, quantitation and analysis of the enzymatic activities of the LPPs measured using intact or broken cell preparations as the source of enzyme.
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Affiliation(s)
- Mark I McDermott
- Departments of Medicine and Cellular and Molecular Biochemistry, Gill Heart Institute, 900 South Limestone Street 326 Charles T. Wethington Building, Lexington KY 40536, USA
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91
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Wu F, Yang Z, Kuang T. Impaired photosynthesis in phosphatidylglycerol-deficient mutant of cyanobacterium Anabaena sp. PCC7120 with a disrupted gene encoding a putative phosphatidylglycerophosphatase. PLANT PHYSIOLOGY 2006; 141:1274-83. [PMID: 16815953 PMCID: PMC1533927 DOI: 10.1104/pp.106.083451] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/11/2006] [Revised: 06/15/2006] [Accepted: 06/15/2006] [Indexed: 05/05/2023]
Abstract
Phosphatidylglycerol (PG) is a ubiquitous phospholipid in thylakoid membranes of cyanobacteria and chloroplasts and plays an important role in the structure and function of photosynthetic membranes. The last step of the PG biosynthesis is dephosphorylation of phosphatidylglycerophosphate (PGP) catalyzed by PGP phosphatase. However, the gene-encoding PGP phosphatase has not been identified and cloned from cyanobacteria or higher plants. In this study, we constructed a PG-deficient mutant from cyanobacterium Anabaena sp. PCC7120 with a disrupted gene (alr1715, a gene for Alr1715 protein, GenBank accession no. BAB78081) encoding a putative PGP phosphatase. The obtained mutant showed an approximately 30% reduction in the cellular content of PG. Following the reduction in the PG content, the photoautotrophical growth of the mutant was restrained, and the cellular content of chlorophyll was decreased. The decreases in net photosynthetic and photosystem II (PSII) activities on a cell basis also occurred in this mutant. Simultaneously, the photochemical efficiency of PSII was considerably declined, and less excitation energy was transferred toward PSII. These findings demonstrate that the alr1715 gene of Anabaena sp. PCC7120 is involved in the biosynthesis of PG and essential for photosynthesis.
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Affiliation(s)
- Feng Wu
- Key Laboratory of Photosynthesis and Environmental Molecular Physiology, Institute of Botany, the Chinese Academy of Sciences, Beijing 100093, China
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92
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Pasquaré SJ, Salvador GA, Giusto NM. Age-associated changes of insulin action on the hydrolysis of diacylglycerol generated from phosphatidic acid. Comp Biochem Physiol B Biochem Mol Biol 2006; 144:311-8. [PMID: 16651016 DOI: 10.1016/j.cbpb.2006.03.005] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2005] [Revised: 03/10/2006] [Accepted: 03/11/2006] [Indexed: 11/16/2022]
Abstract
Age-related changes in insulin action on diacylglycerol (DAG) degradation was studied in rat cerebral cortex synaptosomes. The generation of monoacylglycerol (MAG) and water soluble products (WSP, glycerol plus glycerol-3-phosphate) from DAG was studied in cerebral cortex (CC) synaptosomes from adult (4-month-old) and aged (28-month-old) rats. Additionally, the effect of porcine insulin and tyrosine phosphorylation was evaluated in the same group of animals. In this study we demonstrate that the age-related increase in WSP generation was accompanied by unmodified MAG levels. In the presence of diacylglycerol lipase (DAG lipase) inhibitor, RHC-80267, a lower inhibitory effect on MAG production was observed in CC synaptosomes from aged rats with respect to that in adult membranes. Under these experimental conditions, WSP formation was only diminished in aged membranes. Insulin stimulated MAG and WSP formation at long incubation times (30 min) in adult animals, while it had an inhibitory effect in aged animals. Insulin plus vanadate (as tyrosine-phosphatase inhibitor) inhibited MAG production at short incubation times whereas the same effect was observed in aged animals at long times of incubation. WSP formation was stimulated by insulin plus vanadate both in adult and aged animals at 30 min of incubation. Our results show that insulin differentially modulates MAG and WSP production from exogenous PA in CC synaptosomes from aged rats compared with adult rats.
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Affiliation(s)
- S J Pasquaré
- Instituto de Investigaciones Bioquímicas de Bahía Blanca, Universidad Nacional del Sur and Consejo Nacional de Investigaciones Científicas y Técnicas, CONICET, B8000FWB Bahía Blanca, Argentina
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93
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Gómez-Muñoz A. Ceramide 1-phosphate/ceramide, a switch between life and death. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2006; 1758:2049-56. [PMID: 16808893 DOI: 10.1016/j.bbamem.2006.05.011] [Citation(s) in RCA: 139] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/13/2006] [Revised: 05/04/2006] [Accepted: 05/11/2006] [Indexed: 12/26/2022]
Abstract
Ceramide is a well-characterized sphingolipid metabolite and second messenger that participates in numerous biological processes. In addition to serving as a precursor to complex sphingolipids, ceramide is a potent signaling molecule capable of regulating vital cellular functions. Perhaps its major role in signal transduction is to induce cell cycle arrest, and promote apoptosis. In contrast, little is known about the metabolic or signaling pathways that are regulated by the phosphorylated form of ceramide. It was first demonstrated that ceramide-1-phosphate (C1P) had mitogenic properties, and more recently it has been described as potent inhibitor of apoptosis and inducer of cell survival. C1P and ceramide are antagonistic molecules that can be interconverted in cells by kinase and phosphatase activities. An appropriate balance between the levels of these two metabolites seems to be crucial for cell and tissue homeostasis. Switching this balance towards accumulation of one or the other may result in metabolic dysfunction, or disease. Therefore, the activity of the enzymes that are involved in C1P and ceramide metabolism must be efficiently coordinated to ensure normal cell functioning.
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Affiliation(s)
- Antonio Gómez-Muñoz
- Department of Biochemistry and Molecular Biology, University of the Basque Country, P.O. Box 644, 48080-Bilbao, Spain.
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94
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Garcia-Murillas I, Pettitt T, Macdonald E, Okkenhaug H, Georgiev P, Trivedi D, Hassan B, Wakelam M, Raghu P. lazaro encodes a lipid phosphate phosphohydrolase that regulates phosphatidylinositol turnover during Drosophila phototransduction. Neuron 2006; 49:533-46. [PMID: 16476663 DOI: 10.1016/j.neuron.2006.02.001] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2005] [Revised: 11/30/2005] [Accepted: 02/01/2006] [Indexed: 10/25/2022]
Abstract
An essential step in Drosophila phototransduction is the hydrolysis of phosphatidylinositol 4,5 bisphosphate PI(4,5)P2 by phospholipase Cbeta (PLCbeta) to generate a second messenger that opens the light-activated channels TRP and TRPL. Although the identity of this messenger remains unknown, recent evidence has implicated diacylglycerol kinase (DGK), encoded by rdgA, as a key enzyme that regulates its levels, mediating both amplification and response termination. In this study, we demonstrate that lazaro (laza) encodes a lipid phosphate phosphohydrolase (LPP) that functions during phototransduction. We demonstrate that the synergistic activity of laza and rdgA regulates response termination during phototransduction. Analysis of retinal phospholipids revealed a reduction in phosphatidic acid (PA) levels and an associated reduction in phosphatidylinositol (PI) levels. Together our results demonstrate the contribution of PI depletion to the rdgA phenotype and provide evidence that depletion of PI and its metabolites might be a key signal for TRP channel activation in vivo.
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Affiliation(s)
- Isaac Garcia-Murillas
- Inositide Laboratory, Babraham Institute, Babraham Research Campus, Cambridge CB2 4AT, United Kingdom
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95
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Long J, Yokoyama K, Tigyi G, Pyne N, Pyne S. Lipid phosphate phosphatase-1 regulates lysophosphatidic acid- and platelet-derived-growth-factor-induced cell migration. Biochem J 2006; 394:495-500. [PMID: 16356167 PMCID: PMC1408680 DOI: 10.1042/bj20051674] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
LPPs (lipid phosphate phosphatases) are members of a family of enzymes that catalyse the dephosphorylation of lipid phosphates. The only known form of regulation of this family of enzymes is via de novo expression of LPP isoforms in response to growth factors. In this respect, we evaluated the effect of moderate increases in the expression of recombinant LPP1 on signal transduction by both G-protein-coupled receptors and receptor tyrosine kinases. We present evidence for a novel role of LPP1 in reducing PDGF (platelet-derived growth factor)- and lysophosphatidic acid-induced migration of embryonic fibroblasts. We demonstrate that the overexpression of LPP1 inhibits cell migration by reducing the PDGF-induced activation of p42/p44 MAPK (mitogen-activated protein kinase). This appears to occur via a mechanism that involves the LPP1-induced down-regulation of typical PKC (protein kinase C) isoform(s), which are normally required for PDGF-induced activation of p42/p44 MAPK and migration. In this regard, DAG (diacylglycerol) levels are high and sustained in cells overexpressing LPP1, suggesting a dynamic interconversion of phosphatidic acid into DAG by LPP1. This may account for the effects of LPP1 on cell migration, as sustained DAG is known to down-regulate PKC isoforms in cells. Therefore the physiological changes in the expression levels of LPP1 might represent a heterologous desensitization mechanism for attenuating PKC-mediated signalling and regulation of cell migration.
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Affiliation(s)
- Jaclyn S. Long
- *Department of Physiology and Pharmacology, Strathclyde Institute for Biomedical Sciences, University of Strathclyde, 27 Taylor Street, Glasgow G4 0NR, U.K
| | - Kazuaki Yokoyama
- †Department of Physiology, University of Tennessee Health Science Center Memphis, 894 Union Avenue, Memphis, TN, U.S.A
| | - Gabor Tigyi
- †Department of Physiology, University of Tennessee Health Science Center Memphis, 894 Union Avenue, Memphis, TN, U.S.A
| | - Nigel J. Pyne
- *Department of Physiology and Pharmacology, Strathclyde Institute for Biomedical Sciences, University of Strathclyde, 27 Taylor Street, Glasgow G4 0NR, U.K
| | - Susan Pyne
- *Department of Physiology and Pharmacology, Strathclyde Institute for Biomedical Sciences, University of Strathclyde, 27 Taylor Street, Glasgow G4 0NR, U.K
- To whom correspondence should be addressed (email )
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96
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Fukunaga K, Arita M, Takahashi M, Morris AJ, Pfeffer M, Levy BD. Identification and functional characterization of a presqualene diphosphate phosphatase. J Biol Chem 2006; 281:9490-7. [PMID: 16464866 DOI: 10.1074/jbc.m512970200] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Presqualene diphosphate (PSDP) is a bioactive lipid that rapidly remodels to presqualene monophosphate (PSMP) upon cell activation (Levy, B. D., Petasis, N. A., and Serhan, C. N. (1997) Nature 389, 985-990). Here, we have identified and characterized a phosphatase that converts PSDP to PSMP. Unlike the related polyisoprenyl phosphate farnesyl diphosphate (FDP), PSDP was not a substrate for type 2 lipid phosphate phosphohydrolases. PSDP phosphatase activity was identified in activated human neutrophil (PMN) extracts and partially purified in the presence of Nonidet P-40 with gel filtration and anion exchange chromatography. Peptide sequencing of a candidate phosphatase was consistent with phosphatidic acid phosphatase domain containing 2 (PPAPDC2), an uncharacterized protein that contains a lipid phosphate phosphohydrolase consensus motif. Recombinant PPAPDC2 displayed diphosphate phosphatase activity with a substrate preference for PSDP > FDP > phosphatidic acid. PPAPDC2 activity was independent of Mg(2+) and optimal at pH 7.0 to 8.0. Incubation of [(14)C]FDP with recombinant human squalene synthase led to [(14)C]PSDP and [(14)C]squalene formation, and in the presence of PPAPDC2, [(14)C]PSMP was generated from [(14)C]PSDP. PPAPDC2 mRNA was detected in human PMN, and is widely expressed in human tissues. Together, these findings indicate that PPAPDC2 in human PMN is the first lipid phosphate phosphohydrolase identified for PSDP. Regulation of this activity of the enzyme may have important roles for PMN activation in innate immunity.
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Affiliation(s)
- Koichi Fukunaga
- Pulmonary and Critical Care Medicine Division, Department of Internal Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts 02115, USA
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97
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Long J, Darroch P, Wan K, Kong K, Ktistakis N, Pyne N, Pyne S. Regulation of cell survival by lipid phosphate phosphatases involves the modulation of intracellular phosphatidic acid and sphingosine 1-phosphate pools. Biochem J 2006; 391:25-32. [PMID: 15960610 PMCID: PMC1237135 DOI: 10.1042/bj20050342] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
We have shown previously that LPPs (lipid phosphate phosphatases) reduce the stimulation of the p42/p44 MAPK (p42/p44 mitogen-activated protein kinase) pathway by the GPCR (G-protein-coupled receptor) agonists S1P (sphingosine 1-phosphate) and LPA (lysophosphatidic acid) in serum-deprived HEK-293 cells [Alderton, Darroch, Sambi, McKie, Ahmed, N. J. Pyne and S. Pyne (2001) J. Biol. Chem. 276, 13452-13460]. In the present study, we now show that this can be blocked by pretreating HEK-293 cells with the caspase 3/7 inhibitor, Ac-DEVD-CHO [N-acetyl-Asp-Glu-Val-Asp-CHO (aldehyde)]. Therefore LPP2 and LPP3 appear to regulate the apoptotic status of serum-deprived HEK-293 cells. This was supported further by: (i) caspase 3/7-catalysed cleavage of PARP [poly(ADP-ribose) polymerase] was increased in serum-deprived LPP2-overexpressing compared with vector-transfected HEK-293 cells; and (ii) serum-deprived LPP2- and LPP3-overexpressing cells exhibited limited intranucleosomal DNA laddering, which was absent in vector-transfected cells. Moreover, LPP2 reduced basal intracellular phosphatidic acid levels, whereas LPP3 decreased intracellular S1P in serum-deprived HEK-293 cells. LPP2 and LPP3 are constitutively co-localized with SK1 (sphingosine kinase 1) in cytoplasmic vesicles in HEK-293 cells. Moreover, LPP2 but not LPP3 prevents SK1 from being recruited to a perinuclear compartment upon induction of PLD1 (phospholipase D1) in CHO (Chinese-hamster ovary) cells. Taken together, these data are consistent with an important role for LPP2 and LPP3 in regulating an intracellular pool of PA and S1P respectively, that may govern the apoptotic status of the cell upon serum deprivation.
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Affiliation(s)
- Jaclyn Long
- *Department of Physiology and Pharmacology, Strathclyde Institute for Biomedical Sciences, University of Strathclyde, 27 Taylor Street, Glasgow G4 0NR, U.K
| | - Peter Darroch
- *Department of Physiology and Pharmacology, Strathclyde Institute for Biomedical Sciences, University of Strathclyde, 27 Taylor Street, Glasgow G4 0NR, U.K
| | - Kah Fei Wan
- *Department of Physiology and Pharmacology, Strathclyde Institute for Biomedical Sciences, University of Strathclyde, 27 Taylor Street, Glasgow G4 0NR, U.K
| | - Kok Choi Kong
- *Department of Physiology and Pharmacology, Strathclyde Institute for Biomedical Sciences, University of Strathclyde, 27 Taylor Street, Glasgow G4 0NR, U.K
| | | | - Nigel J. Pyne
- *Department of Physiology and Pharmacology, Strathclyde Institute for Biomedical Sciences, University of Strathclyde, 27 Taylor Street, Glasgow G4 0NR, U.K
| | - Susan Pyne
- *Department of Physiology and Pharmacology, Strathclyde Institute for Biomedical Sciences, University of Strathclyde, 27 Taylor Street, Glasgow G4 0NR, U.K
- To whom correspondence should be addressed (email )
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98
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Hollenback D, Bonham L, Law L, Rossnagle E, Romero L, Carew H, Tompkins CK, Leung DW, Singer JW, White T. Substrate specificity of lysophosphatidic acid acyltransferase beta -- evidence from membrane and whole cell assays. J Lipid Res 2005; 47:593-604. [PMID: 16369050 DOI: 10.1194/jlr.m500435-jlr200] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Membranes of mammalian cells contain lysophosphatidic acid acyltransferase (LPAAT) activities that catalyze the acylation of sn-1-acyl lysophosphatidic acid (lysoPA) to form phosphatidic acid. As the biological roles and biochemical properties of the six known LPAAT isoforms have yet to be fully elucidated, we have characterized human LPAAT-beta activity using two different assays. In a membrane-based assay, LPAAT-beta used lysoPA and lysophosphatidylmethanol (lysoPM) but not other lysophosphoglycerides as an acyl acceptor, and it preferentially transferred 18:1, 18:0, and 16:0 acyl groups over 12:0, 14:0, 20:0, and 20:4 acyl groups. The fact that lysoPM could traverse cell membranes permitted additional characterization of LPAAT-beta activity in cells: PC-3 and DU145 cells converted exogenously added lysoPM and (14)C-labeled 18:1 into (14)C-labeled phosphatidylmethanol (PM). The rate of PM formation was higher in cells that overexpressed LPAAT-beta and was inhibited by the LPAAT-beta inhibitor CT-32501. In contrast, if lysoPM and (14)C-labeled 20:4 were added to PC-3 or DU145 cells, (14)C-labeled PM was also formed, but the rate was neither higher in cells that overexpressed LPAAT-beta nor inhibited by CT-32501. We propose that LPAAT-beta catalyzes the intracellular transfer of 18:1, 18:0, and 16:0 acyl groups but not 20:4 groups to lysoPA.
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Affiliation(s)
- David Hollenback
- Department of Biochemistry, Cell Therapeutics, Inc., Seattle, WA 98119, USA.
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99
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MacLennan NK, Rahib L, Shin C, Fang Z, Horvath S, Dean J, Liao JC, McCabe ERB, Dipple KM. Targeted disruption of glycerol kinase gene in mice: expression analysis in liver shows alterations in network partners related to glycerol kinase activity. Hum Mol Genet 2005; 15:405-15. [PMID: 16368706 DOI: 10.1093/hmg/ddi457] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Glycerol kinase deficiency (GKD) is an X-linked inborn error of metabolism with metabolic and neurological crises. Liver shows the highest level of glycerol kinase (GK) activity in humans and mice. Absence of genotype-phenotype correlations in patients with GKD indicates the involvement of modifier genes, including other network partners. To understand the molecular pathogenesis of GKD, we performed microarray analysis on liver mRNA from neonatal glycerol kinase (Gyk) knockout (KO) and wild-type (WT) mice. Unsupervised learning revealed that the overall gene expression profile of the KO mice was different from that of WT. Real-time PCR confirmed the differences for selected genes. Functional gene enrichment analysis was used to find 56 increased and 37 decreased gene functional categories. PathwayAssist analysis identified changes in gene expression levels of genes involved in organic acid metabolism indicating that GK was part of the same metabolic network which correlates well with the patients with GKD having metabolic acidemia during their episodic crises. Network component analysis (NCA) showed that transcription factors sterol regulatory element-binding protein (SREBP)-1c, carbohydrate response element-binding protein (ChREBP), hepatocyte nuclear factor-4 alpha (HNF-4alpha) and peroxisome proliferative-activated receptor-alpha (PPARalpha) had increased activity in the Gyk KO mice compared with WT mice, whereas SREBP-2 was less active in the Gyk KO mice. These studies show that Gyk deletion causes alterations in expression of genes in several regulatory networks and is the first time NCA has been used to expand on microarray data from a mouse KO model of a human disease.
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Affiliation(s)
- Nicole K MacLennan
- Department of Pediatrics, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095-7088, USA
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Abstract
Lysophosphatidic acid (LPA; 1-acyl-3-phosphoglycerol) exerts its biological activity through both extracellular and intracellular targets. Receptor targets include the cell-surface G-protein-coupled receptors LPA(1-4) and the nuclear PPAR-gamma (peroxisome-proliferator-activated receptor gamma). Enzyme targets include the secreted cancer cell motility factor, autotaxin, and the transmembrane phosphatases, LPP1-3 (where LPP stands for lipid phosphate phosphatase). Ion channel targets include the two pore domain ion channels in the TREK family, TREK-1, TREK-2 and TRAAK. Structural features of these targets and their interactions with LPA are reviewed.
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