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Sample records for a-dependent lysophosphatidic acid

  1. CGI-58/ABHD5 is a coenzyme A-dependent lysophosphatidic acid acyltransferase

    PubMed Central

    Montero-Moran, Gabriela; Caviglia, Jorge M.; McMahon, Derek; Rothenberg, Alexis; Subramanian, Vidya; Xu, Zhi; Lara-Gonzalez, Samuel; Storch, Judith; Carman, George M.; Brasaemle, Dawn L.

    2010-01-01

    Mutations in human CGI-58/ABHD5 cause Chanarin-Dorfman syndrome (CDS), characterized by excessive storage of triacylglycerol in tissues. CGI-58 is an α/β-hydrolase fold enzyme expressed in all vertebrates. The carboxyl terminus includes a highly conserved consensus sequence (HXXXXD) for acyltransferase activity. Mouse CGI-58 was expressed in Escherichia coli as a fusion protein with two amino terminal 6-histidine tags. Recombinant CGI-58 displayed acyl-CoA-dependent acyltransferase activity to lysophosphatidic acid, but not to other lysophospholipid or neutral glycerolipid acceptors. Production of phosphatidic acid increased with time and increasing concentrations of recombinant CGI-58 and was optimal between pH 7.0 and 8.5. The enzyme showed saturation kinetics with respect to 1-oleoyl-lysophosphatidic acid and oleoyl-CoA and preference for arachidonoyl-CoA and oleoyl-CoA. The enzyme showed slight preference for 1-oleoyl lysophosphatidic acid over 1-palmitoyl, 1-stearoyl, or 1-arachidonoyl lysophosphatidic acid. Recombinant CGI-58 showed intrinsic fluorescence for tryptophan that was quenched by the addition of 1-oleoyl-lysophosphatidic acid, oleoyl-CoA, arachidonoyl-CoA, and palmitoyl-CoA, but not by lysophosphatidyl choline. Expression of CGI-58 in fibroblasts from humans with CDS increased the incorporation of radiolabeled fatty acids released from the lipolysis of stored triacylglycerols into phospholipids. CGI-58 is a CoA-dependent lysophosphatidic acid acyltransferase that channels fatty acids released from the hydrolysis of stored triacylglycerols into phospholipids. PMID:19801371

  2. Signalling properties of lysophosphatidic acid.

    PubMed

    Durieux, M E; Lynch, K R

    1993-06-01

    Lysophosphatidic acid (LPA) is the simplest natural phospholipid, primarily known as a membrane component and metabolic intermediate. However, a remarkable variety of biological effects of this compound have come to light, seemingly pointing to an additional role for LPA as a signalling molecule. In this review, Marcel Durieux and Kevin Lynch integrate the recent information that indicates that LPA could be an intercellular messenger, possibly acting through a G protein-coupled receptor, and with a role in cell growth and motility.

  3. Lysophosphatidic acid signalling in development

    PubMed Central

    Sheng, Xiaoyan; Yung, Yun C.; Chen, Allison; Chun, Jerold

    2015-01-01

    Lysophosphatidic acid (LPA) is a bioactive phospholipid that is present in all tissues examined to date. LPA signals extracellularly via cognate G protein-coupled receptors to mediate cellular processes such as survival, proliferation, differentiation, migration, adhesion and morphology. These LPA-influenced processes impact many aspects of organismal development. In particular, LPA signalling has been shown to affect fertility and reproduction, formation of the nervous system, and development of the vasculature. Here and in the accompanying poster, we review the developmentally related features of LPA signalling. PMID:25852197

  4. [Lysophosphatidic acid and human erythrocyte aggregation].

    PubMed

    Sheremet'ev, Iu A; Popovicheva, A N; Levin, G Ia

    2014-01-01

    The effects of lysophosphatidic acid on the morphology and aggregation of human erythrocytes has been studied. Morphology of erythrocytes and their aggregates were studied by light microscopy. It has been shown that lysophosphatidic acid changes the shape of red blood cells: diskocyte become echinocytes. Aggregation of red blood cells (rouleaux) was significantly reduced in autoplasma. At the same time there is a strong aggregation of echinocytes. This was accompanied by the formation of microvesicles. Adding normal plasma to echinocytes restores shape and aggregation of red blood cells consisting of "rouleaux". A possible mechanism of action of lysophosphatidic acid on erythrocytes is discussed.

  5. Possible effect of lysophosphatidic acid on cell proliferation and involvement of lysophosphatidic acid and lysophosphatidic acid receptors in mechanical stretch-induced mitogen-activated protein kinase.

    PubMed

    Kawashima, Yohei; Kushida, Nobuhiro; Kokubun, Shuko; Ogawa, Soichiro; Shiomi, Homare; Ishibashi, Kei; Aikawa, Ken; Ikegami, Kentaro; Nomiya, Masanori; Yamaguchi, Osamu

    2015-08-01

    To determine whether lysophosphatidic acid activates the mitogen-activated protein kinase and increases DNA synthesis in human bladder smooth muscle cells, and to examine the involvement of lysophosphatidic acid and lysophosphatidic acid receptor in mechanical stretch-induced mitogen-activated protein kinase activation in cultured human bladder smooth muscle cells. TaqMan reverse transcription polymerase chain reaction was used to determine the mRNA expression levels of six lysophosphatidic acid receptor subtypes. Mitogen-activated protein kinase activity enhanced by either lysophosphatidic acid or mechanical stretch was measured by western blotting. The effect of lysophosphatidic acid on DNA synthesis was assessed by 5-bromo-2'-deoxy-uridine incorporation assay. Lysophosphatidic acid 1 subtype mRNA was predominantly expressed (96%). Lysophosphatidic acid activated the mitogen-activated protein kinase in a concentration-dependent manner. C-jun NH2 -terminal kinase showed the highest activity among the three subsets of the mitogen-activated protein kinase family members (c-jun NH2 -terminal kinase, extracellular signal-regulated kinases, p38). Lysophosphatidic acid also increased incorporation of 5-bromo-2'-deoxy-uridine. These responses were suppressed by Ki16425 (lysophosphatidic acid receptor antagonist). Mechanical stretch mainly induced c-jun NH2 -terminal kinase activation. This activation was partially inhibited by Ki16425. Lysophosphatidic acid might activate the c-jun NH2 -terminal kinase component of the mitogen-activated protein kinase family and DNA synthesis through lysophosphatidic acid receptors (presumably, through lysophosphatidic acid 1) in human bladder smooth muscle cells. The present study also implicates the involvement of lysophosphatidic acid and lysophosphatidic acid receptors in mechanical stretch-induced c-jun NH2 -terminal kinase activation. Lysophosphatidic acid receptor can be partially activated by mechanical stretching through

  6. Lysophosphatidic acid and renal fibrosis

    PubMed Central

    Pradère, Jean-Philippe; Gonzalez, Julien; Klein, Julie; Valet, Philippe; Grès, Sandra; Salant, David; Bascands, Jean-Loup; Saulnier-Blache, Jean-Sébastien; Schanstra, Joost P.

    2008-01-01

    Summary The development of fibrosis involves a multitude of events and molecules. Until now the majority of these molecules were found to be proteins or peptides. But recent data show significant involvement of the phospholipid lysophosphatidic acid (LPA) in the development of pulmonary, liver and renal fibrosis. The latest data on the role of LPA and the G-protein-coupled LPA1 receptor in the development of renal fibrosis will be discussed. LPA1 receptor-activation was found to be associated with increased vascular leakage and increased fibroblast recruitment in pulmonary fibrosis. Furthermore, in renal fibrosis LPA1 receptor-activation stimulates macrophage recruitment and connective tissue growth factor expression. The observations make this receptor an interesting alternative and new therapeutic target in fibrotic diseases. PMID:18455518

  7. Lysophosphatidic acid and renal fibrosis.

    PubMed

    Pradère, Jean-Philippe; Gonzalez, Julien; Klein, Julie; Valet, Philippe; Grès, Sandra; Salant, David; Bascands, Jean-Loup; Saulnier-Blache, Jean-Sébastien; Schanstra, Joost P

    2008-09-01

    The development of fibrosis involves a multitude of events and molecules. Until now the majority of these molecules were found to be proteins or peptides. But recent data show significant involvement of the phospholipid lysophosphatidic acid (LPA) in the development of pulmonary, liver and renal fibrosis. The latest data on the role of LPA and the G-protein-coupled LPA1 receptor in the development of renal fibrosis will be discussed. LPA1-receptor activation was found to be associated with increased vascular leakage and increased fibroblast recruitment in pulmonary fibrosis. Furthermore, in renal fibrosis LPA1-receptor activation stimulates macrophage recruitment and connective tissue growth factor expression. The observations make this receptor an interesting alternative and new therapeutic target in fibrotic diseases.

  8. Lysophosphatidic acid (LPA) and angiogenesis.

    PubMed

    Rivera-Lopez, Carol M; Tucker, Amy L; Lynch, Kevin R

    2008-01-01

    Lysophosphatidic acid (LPA) is a simple lipid with many important biological functions such as the regulation of cellular proliferation, cellular migration, differentiation, and suppression of apoptosis. Although a direct angiogenic effect of LPA has not been reported to date, there are indications that LPA promotes angiogenesis. In addition, LPA is a chemoattractant for cultured endothelial cells and promotes barrier function in such cultures. To test the hypothesis that LPA is angiogenic, we used the chicken chorio-allantoic membrane (CAM) assay. Sequence analysis of the cloned, full-length chicken LPA receptor cDNAs revealed three receptor types that are orthologous to the mammalian LPA(1), LPA(2), and LPA(3) receptors. We document herein that LPA is angiogenic in the CAM system and further that synthetic LPA receptor agonists and antagonists mimic or block this response, respectively. Our results predict that LPA receptor antagonists are a possible therapeutic route to interdicting angiogenesis.

  9. Lysophosphatidic acid induces osteocyte dendrite outgrowth

    SciTech Connect

    Karagiosis, Sue A.; Karin, Norm J.

    2007-05-25

    A method was developed to measure dendrite formation in bone cells. Lysophosphatidic acid (LPA) was found to stimulate dendrite outgrowth. It is postulated that LPA plays a role in regulating the osteocyte network in vivo.

  10. Lysophosphatidic acid in atherosclerotic diseases

    PubMed Central

    Schober, Andreas; Siess, Wolfgang

    2012-01-01

    Lysophosphatidic acid (LPA) is a potent bioactive phospholipid. As many other biological active lipids, LPA is an autacoid: it is formed locally on demand, and it acts locally near its site of synthesis. LPA has a plethora of biological activities on blood cells (platelets, monocytes) and cells of the vessel wall (endothelial cells, smooth muscle cells, macrophages) that are all key players in atherosclerotic and atherothrombotic processes. The specific cellular actions of LPA are determined by its multifaceted molecular structures, the expression of multiple G-protein coupled LPA receptors at the cell surface and their diverse coupling to intracellular signalling pathways. Numerous studies have now shown that LPA has thrombogenic and atherogenic actions. Here, we aim to provide a comprehensive, yet concise, thoughtful and critical review of this exciting research area and to pinpoint potential pharmacological targets for inhibiting thrombogenic and atherogenic activities of LPA. We hope that the review will serve to accelerate knowledge of basic and clinical science, and to foster drug development in the field of LPA and atherosclerotic/atherothrombotic diseases. PMID:22568609

  11. Lysophosphatidic acid synthesis and phospholipid metabolism in rat mast cells

    SciTech Connect

    Fagan, D.L.

    1986-01-01

    The role of lysophosphatidic acid in mast cell response to antigen was investigated using an isolated rat serosal mast cell model. The cells were incubated with monoclonal murine immunoglobulin E to the dinitrophenyl hapten and prelabeled with /sup 32/P-orthophosphate or /sup 3/H-fatty acids. Lysophosphatidic acid was isolated form cell extracts by 2-dimensional thin-layer chromatography, and the incorporated radioactivity was assessed by liquid scintillation counting. Lysophosphatidic acid labeling with /sup 32/P was increased 2-4 fold within 5 minutes after the addition of antigen or three other mast cell agonists. Functional group analyses unequivocally showed that the labeled compound was lysophosphatidic acid. Lysophosphatidic acid synthesis was dependent on the activity of diacylglycerol lipase, suggesting formation from monoacylglycerol. In addition, the studies of lysophosphatidic acid synthesis suggest that the addition of antigen to mast cells may initiate more than one route of phospholipid degradation and resynthesis. Whatever the origin of lysophosphatidic acid, the results of this study demonstrated that lysophosphatidic acid synthesis is stimulated by a variety of mast cell agonists. Dose-response, kinetic, and pharmacologic studies showed close concordance between histamine release and lysophosphatidic acid labeling responses. These observations provide strong evidence that lysophosphatidic acid plays an important role in mast cell activation.

  12. Lysophosphatidic acid in vascular development and disease.

    PubMed

    Teo, Siew T; Yung, Yun C; Herr, Deron R; Chun, Jerold

    2009-08-01

    Lysophosphatidic acid (LPA) is a small signaling lipid that is capable of stimulating a plethora of different cellular responses through the activation of its family of cognate G protein-coupled receptors. LPA mediates a wide range of biological effects in many tissue types that have been recently reviewed; however, its effects on vasculature development and function have received comparatively less examination. In this review, literature on the actions of LPA in three main aspects of vascular development (vasculogenesis, angiogenesis, and vascular maturation) is discussed. In addition, evidence for the roles of LPA signaling in the formation of secondary vascular structures, such as the blood brain barrier, is considered, consistent with significant roles for LPA signaling in vascular development, function, and disease.

  13. Lysophosphatidic Acid (LPA) Signaling in Vertebrate Reproduction

    PubMed Central

    Ye, Xiaoqin; Chun, Jerold

    2009-01-01

    Lysophosphatidic acid (LPA) is a cell membrane phospholipid metabolite that can act as an extracellular signal. Its effects are mediated through at least five G protein-coupled receptors (GPCRs), LPA1-5, and likely others as well. Studies in multiple species including LPA receptor-deficient mice and humans have identified or implicated important roles for receptor-mediated LPA signaling in multiple aspects of vertebrate reproduction. These include ovarian function, spermatogenesis, fertilization, early embryo development, embryo implantation, embryo spacing, decidualization, pregnancy maintenance, and parturition. LPA signaling may also have pathological consequences, influencing aspects of endometriosis and ovarian cancer. Here we review recent progress in LPA signaling research relevant to female and male reproduction. PMID:19836970

  14. Lysophosphatidic Acid Regulation and Roles in Human Prostate Cancer

    DTIC Science & Technology

    2006-08-01

    DAMD17-02-1-0060 TITLE: Lysophosphatidic Acid Regulation and Roles in Human Prostate Cancer PRINCIPAL INVESTIGATOR: Sarah Spiegel...Final 3. DATES COVERED (From - To) 2 Jan 2002 – 31 Jul 2006 4. TITLE AND SUBTITLE 5a. CONTRACT NUMBER Lysophosphatidic Acid Regulation and Roles ...important role in the pathophysiology of prostate cancer. Therefore, targeting this kinase, offers additional therapeutic benefits in treatment of

  15. Lysophosphatidic acid effects on atherosclerosis and thrombosis

    PubMed Central

    Cui, Mei-Zhen

    2011-01-01

    Lysophosphatidic acid (LPA) has been found to accumulate in high concentrations in atherosclerotic lesions. LPA is a bioactive phospholipid produced by activated platelets and formed during the oxidation of LDL. Accumulating evidence suggests that this lipid mediator may serve as an important risk factor for development of atherosclerosis and thrombosis. The role of LPA in atherogenesis is supported by the evidence that LPA: stimulates endothelial cells to produce adhesion molecules and chemoattractants; induces smooth muscle cells to produce inflammatory cytokines; stimulates smooth muscle cell dedifferentiation, proliferation, and migration; increases monocyte migration and decreases monocyte-derived cell emigration from the vessel wall; induces hypertension and vascular neointimal formation in vivo; and promotes plaque progression in a mouse atherosclerosis model. The role of LPA in thrombogenesis is supported by the evidence that LPA markedly induces the aggregation of platelets and the expression of tissue factor, which is the principal initiator of blood coagulation. Recent experimental data indicate that LPA is produced by specific enzymes and that LPA binds to and activates multiple G-protein-coupled receptors, leading to intracellular signaling. Therapeutics targeting LPA biosynthesis, metabolism and signaling pathways could be viable for prevention and treatment of atherosclerosis and thrombosis. PMID:22162980

  16. Aiming drug discovery at lysophosphatidic acid targets

    PubMed Central

    Tigyi, Gabor

    2010-01-01

    Lysophosphatidic acid (LPA, 1-radyl-2-hydroxy-sn-glycero-3-phosphate) is the prototype member of a family of lipid mediators and second messengers. LPA and its naturally occurring analogues interact with G protein-coupled receptors on the cell surface and a nuclear hormone receptor within the cell. In addition, there are several enzymes that utilize LPA as a substrate or generate it as a product and are under its regulatory control. LPA is present in biological fluids, and attempts have been made to link changes in its concentration and molecular composition to specific disease conditions. Through their many targets, members of the LPA family regulate cell survival, apoptosis, motility, shape, differentiation, gene transcription, malignant transformation and more. The present review depicts arbitrary aspects of the physiological and pathophysiological actions of LPA and attempts to link them with select targets. Many of us are now convinced that therapies targeting LPA biosynthesis and signalling are feasible for the treatment of devastating human diseases such as cancer, fibrosis and degenerative conditions. However, successful targeting of the pathways associated with this pleiotropic lipid will depend on the future development of as yet undeveloped pharmacons. PMID:20735414

  17. Lysophosphatidic acid and signaling in sensory neurons.

    PubMed

    Oude Elferink, Ronald P J; Bolier, Ruth; Beuers, Ulrich H

    2015-01-01

    Lysophosphatidic acid is a potent signaling lipid molecule that has initially been characterized as a growth factor. However, later studies have revealed many more functions such as modulation of cell shape, cell migration, prevention of apoptosis, platelet aggregation, wound healing, osteoclast differentiation, vasopressor activity, embryo implantation, angiogenesis, lung fibrosis, hair growth and more. The molecule mainly acts through the activation of a set of at least 6 G-protein-coupled receptors (LPA1-6), but intracellular LPA was also shown to signal through the activation of the nuclear receptor PPARγ. In this short review we discuss the recent observations which suggest that in pathological conditions LPA also modulates signaling in sensory neurons. Thus, LPA has been shown to play a role in the initiation of neuropathic pain and, more recently, a relation was observed between increased LPA levels in the circulation and cholestatic itch. The mechanism by which this occurs remains to be elucidated. This article is part of a Special Issue entitled Linking transcription to physiology in lipodomics. Copyright © 2014 Elsevier B.V. All rights reserved.

  18. Lysophosphatidic acid induces osteocyte dendrite outgrowth.

    PubMed

    Karagiosis, Sue A; Karin, Norman J

    2007-05-25

    Osteocytes elaborate an extensive mechanosensory network in bone matrix and communicate intercellularly via gap junctions established at dendrite termini. We developed a method to measure osteocyte dendritogenesis in vitro using a modified transwell assay and determined that the lipid growth factor lysophosphatidic acid (LPA) is a potent stimulator of dendrite outgrowth in MLO-Y4 osteocytes. The stimulatory effects were dose-dependent with maximal outgrowth observed within a physiological range of LPA. LPA-treated osteocytes exhibited distinct rearrangements of the actin cytoskeleton and a more stellate morphology than control cells. LPA also promoted osteocyte chemotaxis, suggesting a shared molecular mechanism between dendrite outgrowth and cell motility. The LPA-induced increase in dendrite formation was blocked by the specific LPA-receptor antagonist Ki16425 and by pertussis toxin. Bone cells in vivo encounter platelet-derived LPA in regions of bone damage, and we postulate that this lipid factor is important for re-establishing osteocyte connectivity during fracture repair.

  19. Lysophosphatidic Acid Regulation and Roles in Human Prostate Cancer

    DTIC Science & Technology

    2005-01-01

    be generated by other pathways. LPA is produced from phosphatidic acid 4 ") (PA) in activated platelets and ovarian and prostate cancer cells by...material. Appendix 1 JCB in revision 2 ABSTRACT The bioactive phospholipids, lysophosphatidic acid (LPA) and phosphatidic acid (PA), regulate pivotal...glycerolipid synthesis, abundant evidence now indicates that bioactive LPA can also be generated by other pathways. LPA is produced from phosphatidic acid (PA

  20. Promising Pharmacological Directions in the World of Lysophosphatidic Acid Signaling

    PubMed Central

    Stoddard, Nicole C.; Chun, Jerold

    2015-01-01

    Lysophosphatidic acid (LPA) is a signaling lipid that binds to six known lysophosphatidic acid receptors (LPARs), named LPA1-LPA6. These receptors initiate signaling cascades relevant to development, maintenance, and healing processes throughout the body. The diversity and specificity of LPA signaling, especially in relation to cancer and autoimmune disorders, makes LPA receptor modulation an attractive target for drug development. Several LPAR-specific analogues and small molecules have been synthesized and are efficacious in attenuating pathology in disease models. To date, at least three compounds have passed phase I and phase II clinical trials for idiopathic pulmonary fibrosis and systemic sclerosis. This review focuses on the promising therapeutic directions emerging in LPA signaling toward ameliorating several diseases, including cancer, fibrosis, arthritis, hydrocephalus, and traumatic injury. PMID:25593637

  1. Lysophosphatidic Acid Signaling through the Lysophosphatidic Acid-1 Receptor Is Required for Alveolarization.

    PubMed

    Funke, Manuela; Knudsen, Lars; Lagares, David; Ebener, Simone; Probst, Clemens K; Fontaine, Benjamin A; Franklin, Alicia; Kellner, Manuela; Kühnel, Mark; Matthieu, Stephanie; Grothausmann, Roman; Chun, Jerold; Roberts, Jesse D; Ochs, Matthias; Tager, Andrew M

    2016-07-01

    Lysophosphatidic acid (LPA) signaling through one of its receptors, LPA1, contributes to both the development and the pathological remodeling after injury of many organs. Because we found previously that LPA-LPA1 signaling contributes to pulmonary fibrosis, here we investigated whether this pathway is also involved in lung development. Quantitative assessment of lung architecture of LPA1-deficient knock-out (KO) and wild-type (WT) mice at 3, 12, and 24 weeks of age using design-based stereology suggested the presence of an alveolarization defect in LPA1 KO mice at 3 weeks, which persisted as alveolar numbers increased in WT mice into adulthood. Across the ages examined, the lungs of LPA1 KO mice exhibited decreased alveolar numbers, septal tissue volumes, and surface areas, and increased volumes of the distal airspaces. Elastic fibers, critical to the development of alveolar septa, appeared less organized and condensed and more discontinuous in KO alveoli starting at P4. Tropoelastin messenger RNA expression was decreased in KO lungs, whereas expression of matrix metalloproteinases degrading elastic fibers was either decreased or unchanged. These results are consistent with the abnormal lung phenotype of LPA1 KO mice, being attributable to reduced alveolar septal formation during development, rather than to increased septal destruction as occurs in the emphysema of chronic obstructive pulmonary disease. Peripheral septal fibroblasts and myofibroblasts, which direct septation in late alveolarization, demonstrated reduced production of tropoelastin and matrix metalloproteinases, and diminished LPA-induced migration, when isolated from LPA1 KO mice. Taken together, our data suggest that LPA-LPA1 signaling is critically required for septation during alveolarization.

  2. Simple enrichment and analysis of plasma lysophosphatidic acids.

    PubMed

    Wang, Jialu; Sibrian-Vazquez, Martha; Escobedo, Jorge O; Lowry, Mark; Wang, Lei; Chu, Yu-Hsuan; Moore, Richard G; Strongin, Robert M

    2013-11-21

    A simple and highly efficient technique for the analysis of lysophosphatidic acid (LPA) subspecies in human plasma is described. The streamlined sample preparation protocol furnishes the five major LPA subspecies with excellent recoveries. Extensive analysis of the enriched sample reveals only trace levels of other phospholipids. This level of purity not only improves MS analyses, but enables HPLC post-column detection in the visible region with a commercially available fluorescent phospholipids probe. Human plasma samples from different donors were analyzed using the above method and validated by LC-ESI/MS/MS.

  3. Prostatic acid phosphatase degrades lysophosphatidic acid in seminal plasma.

    PubMed

    Tanaka, Masayuki; Kishi, Yasuhiro; Takanezawa, Yasukazu; Kakehi, Yoshiyuki; Aoki, Junken; Arai, Hiroyuki

    2004-07-30

    Lysophosphatidic acid (LPA) is a lipid mediator with multiple biological activities and is detected in various biological fluids, including human seminal plasma. Due to its cell proliferation stimulatory and anti-apoptotic activities, LPA has been implicated in the progression of some cancers such as ovarian cancer and prostate cancer. Here, we show that prostatic acid phosphatase, which is a non-specific phosphatase and which has been implicated in the progression of prostate cancer, inactivates LPA in human seminal plasma. Human seminal plasma contains both an LPA-synthetic enzyme, lysoPLD, which converts lysophospholipids to LPA and is responsible for LPA production in serum, and its major substrate, lysophosphatidylcholine. In serum, LPA accumulated during incubation at 37 degrees C. However, in seminal plasma, LPA did not accumulate. This discrepancy is explained by the presence of a strong LPA-degrading activity. Incubation of LPA with seminal plasma resulted in the disappearance of LPA and an accompanying accumulation of monoglyceride showing that LPA is degraded by phosphatase activity present in the seminal plasma. When seminal plasma was incubated in the presence of a phosphatase inhibitor, sodium orthovanadate, LPA accumulated, indicating that LPA is produced and degraded in the fluid. Biochemical characterization of the LPA-phosphatase activity identified two phosphatase activities in human seminal plasma. By Western blotting analysis in combination with several column chromatographies, the major activity was revealed to be identical to prostatic acid phosphatase. The present study demonstrates active LPA metabolism in seminal plasma and indicates the possible role of LPA signaling in male sexual organs including prostate cancer.

  4. Intragastrically administered lysophosphatidic acids protect against gastric ulcer in rats under water-immersion restraint stress.

    PubMed

    Adachi, Mika; Horiuchi, Gou; Ikematsu, Natsuki; Tanaka, Tamotsu; Terao, Junji; Satouchi, Kiyoshi; Tokumura, Akira

    2011-08-01

    Lysophosphatidic acid exerts important physiological effects on many types of animal cells through its specific binding to several G protein-coupled receptors. In particular, its potent wound-healing effect has attracted much attention. To determine whether lysophosphatidic acids in a foodstuff and Chinese medicine are effective in protecting against gastric ulcer, we subjected rats to water-immersion restraint stress. Three direct administrations of a solution of lysophosphatidic acid with a C18 fatty acyl group to the rat stomach in a concentration range of 0.001-0.1 mM resulted in a significant reduction in the number of gastric ulcers induced during water-immersion restraint stress, and the potencies were as follows: linoleoyl species=α-linolenoyl species>oleoyl species. Intragastric administrations of a solution of highly purified lysophosphatidic acid from soybean lecithin significantly protected against the stress-induced gastric ulcers at lower concentrations than partially purified lysophosphatidic acid from soybean lecithin did. In addition, administration of a decocted solution of antyu-san, and lysophosphatidic acid-rich Chinese medicine, to the stomach was more effective in protecting against stress-induced ulcer than decoctations of antyu-san lacking the corydalis tuber component that is rich in lysophosphatidic acid. These results clearly show that lysophosphatidic acid is the effective component of soybean lecithin and antyu-san in protection against stress-induced gastric ulcer in the rat model, and suggest that daily intake of lysophosphatidic acid-rich foods or Chinese medicines may be beneficial for prevention of stress-induced gastric ulcer in human subjects.

  5. Dysregulation of lysophosphatidic acids in multiple sclerosis and autoimmune encephalomyelitis.

    PubMed

    Schmitz, K; Brunkhorst, R; de Bruin, N; Mayer, C A; Häussler, A; Ferreiros, N; Schiffmann, S; Parnham, M J; Tunaru, S; Chun, J; Offermanns, S; Foerch, C; Scholich, K; Vogt, J; Wicker, S; Lötsch, J; Geisslinger, G; Tegeder, I

    2017-06-02

    Bioactive lipids contribute to the pathophysiology of multiple sclerosis. Here, we show that lysophosphatidic acids (LPAs) are dysregulated in multiple sclerosis (MS) and are functionally relevant in this disease. LPAs and autotaxin, the major enzyme producing extracellular LPAs, were analyzed in serum and cerebrospinal fluid in a cross-sectional population of MS patients and were compared with respective data from mice in the experimental autoimmune encephalomyelitis (EAE) model, spontaneous EAE in TCR(1640) mice, and EAE in Lpar2 (-/-) mice. Serum LPAs were reduced in MS and EAE whereas spinal cord LPAs in TCR(1640) mice increased during the 'symptom-free' intervals, i.e. on resolution of inflammation during recovery hence possibly pointing to positive effects of brain LPAs during remyelination as suggested in previous studies. Peripheral LPAs mildly re-raised during relapses but further dropped in refractory relapses. The peripheral loss led to a redistribution of immune cells from the spleen to the spinal cord, suggesting defects of lymphocyte homing. In support, LPAR2 positive T-cells were reduced in EAE and the disease was intensified in Lpar2 deficient mice. Further, treatment with an LPAR2 agonist reduced clinical signs of relapsing-remitting EAE suggesting that the LPAR2 agonist partially compensated the endogenous loss of LPAs and implicating LPA signaling as a novel treatment approach. Graphical summary of lysophosphatidic signaling in multiple sclerosis.

  6. Comparative analyses of lysophosphatidic acid receptor-mediated signaling.

    PubMed

    Fukushima, Nobuyuki; Ishii, Shoichi; Tsujiuchi, Toshifumi; Kagawa, Nao; Katoh, Kazutaka

    2015-06-01

    Lysophosphatidic acid (LPA) is a bioactive lipid mediator that activates G protein-coupled LPA receptors to exert fundamental cellular functions. Six LPA receptor genes have been identified in vertebrates and are classified into two subfamilies, the endothelial differentiation genes (edg) and the non-edg family. Studies using genetically engineered mice, frogs, and zebrafish have demonstrated that LPA receptor-mediated signaling has biological, developmental, and pathophysiological functions. Computational analyses have also identified several amino acids (aa) critical for LPA recognition by human LPA receptors. This review focuses on the evolutionary aspects of LPA receptor-mediated signaling by comparing the aa sequences of vertebrate LPA receptors and LPA-producing enzymes; it also summarizes the LPA receptor-dependent effects commonly observed in mouse, frog, and fish.

  7. Functional characterization of lysophosphatidic acid phosphatase from Arabidopsis thaliana.

    PubMed

    Reddy, Venky Sreedhar; Rao, D K Venkata; Rajasekharan, Ram

    2010-04-01

    Lysophosphatidic acid (LPA) acts as a signaling molecule that regulates diverse cellular processes and it can rapidly be metabolized by phosphatase and acyltransferase. LPA phosphatase gene has not been identified and characterized in plants so far. The BLAST search revealed that the At3g03520 is similar to phospholipase family, and distantly related to bacterial phosphatases. The conserved motif, (J)4XXXNXSFD, was identified in both At3g03520 like phospholipases and acid phosphatases. In silico expression analysis of At3g03520 revealed a high expression during phosphate starvation and abiotic stresses. This gene was overexpressed in Escherichia coli and shown to posses LPA specific phosphatase activity. These results suggest that this gene possibly plays a role in signal transduction and storage lipid synthesis.

  8. Polyunsaturated lysophosphatidic acid as a potential asthma biomarker

    PubMed Central

    Ackerman, Steven J; Park, Gye Young; Christman, John W; Nyenhuis, Sharmilee; Berdyshev, Evgeny; Natarajan, Viswanathan

    2016-01-01

    Lysophosphatidic acid (LPA), a lipid mediator in biological fluids and tissues, is generated mainly by autotaxin that hydrolyzes lysophosphatidylcholine to LPA and choline. Total LPA levels are increased in bronchoalveolar lavage fluid from asthmatic lung, and are strongly induced following subsegmental bronchoprovocation with allergen in subjects with allergic asthma. Polyunsaturated molecular species of LPA (C22:5 and C22:6) are selectively synthesized in the airways of asthma subjects following allergen challenge and in mouse models of allergic airway inflammation, having been identified and quantified by LC/MS/MS lipidomics. This review discusses current knowledge of LPA production in asthmatic lung and the potential utility of polyunsaturated LPA molecular species as novel biomarkers in bronchoalveolar lavage fluid and exhaled breath condensate of asthma subjects. PMID:26808693

  9. Design of anticancer lysophosphatidic acid agonists and antagonists.

    PubMed

    Parrill, Abby L

    2014-05-01

    Lysophosphatidic acid (LPA) and its receptors, LPA1-6, are integral parts of signaling pathways involved in cellular proliferation, migration and survival. These signaling pathways are of therapeutic interest for the treatment of multiple types of cancer and to reduce cancer metastasis and side effects. Validated therapeutic potential of key receptors, as well as recent structure-activity relationships yielding compounds with low nanomolar potencies are exciting recent advances in the field. Some compounds have proven efficacious in vivo against tumor proliferation and metastasis, bone cancer pain and the pulmonary fibrosis that can result as a side effect of pulmonary cancer radiation treatment. However, recent studies have identified that LPA contributes through multiple pathways to the development of chemotherapeutic resistance suggesting new applications for LPA antagonists in cancer treatment. This review summarizes the roles of LPA signaling in cancer pathophysiology and recent progress in the design and evaluation of LPA agonists and antagonists.

  10. Functional lysophosphatidic acid receptors expressed in Oryzias latipes.

    PubMed

    Morimoto, Yuji; Ishii, Shoichi; Ishibashi, Jun-Ichi; Katoh, Kazutaka; Tsujiuchi, Toshifumi; Kagawa, Nao; Fukushima, Nobuyuki

    2014-11-10

    Lysophosphatidic acid (LPA) signaling is known to play biological and pathophysiological roles in many types of animals. Medaka (Oryzias latipes) is an experimental fish that can be easily maintained, propagated, and analyzed, and whose genome has been completely sequenced. However, there is limited information available regarding medaka LPA receptors. Here, using information from the medaka genome database, we examine the genomic structures, expression, and functions of six LPA receptor genes, Lpar1-Lpar6. Our analyses reveal that the genomic structures of Lpar1 and Lpar4 are different from those deduced from the database. Functional analyses using a heterologous expression system demonstrate that all medaka LPA receptors except for LPA5b respond to LPA treatment with cytoskeletal changes. These findings provide useful information on the structure and function of medaka LPA receptor genes, and identify medaka as a useful experimental model for exploration of the biological significance of LPA signaling. Copyright © 2014 Elsevier B.V. All rights reserved.

  11. Development of lysophosphatidic acid pathway modulators as therapies for fibrosis.

    PubMed

    Budd, David C; Qian, Yimin

    2013-10-01

    Lysophosphatidic acid (LPA) is a class of bioactive phospholipid that displays a wide range of cellular effects via LPA receptors, of which six have been identified (LPAR1-6). In serum and plasma, LPA production occurs mainly by the hydrolysis of lysophosphatidylcholine by the phospholipase D activity of autotaxin (ATX). The involvement of the LPA pathway in driving chronic wound-healing conditions, such as idiopathic pulmonary fibrosis, has suggested targets in this pathway could provide potential therapeutic approaches. Mice with LPAR1 knockout or tissue-specific ATX deletion have demonstrated reduced lung fibrosis following bleomycin challenge. Therefore, strategies aimed at antagonizing LPA receptors or inhibiting ATX have gained considerable attention. This Review will summarize the current status of identifying small-molecule modulators of the LPA pathway. The therapeutic utility of LPA modulators for the treatment of fibrotic diseases will soon be revealed as clinical trials are already in progress in this area.

  12. Lysophosphatidic acid receptor (LPAR) modulators: The current pharmacological toolbox.

    PubMed

    Llona-Minguez, Sabin; Ghassemian, Artin; Helleday, Thomas

    2015-04-01

    Lysophosphatidic acids (LPA) are key lipid-signalling molecules that regulate a remarkably diverse set of cellular events, such as motility, chemotaxis, cell cycle progression, viability, and wound healing. The physiological and pathophysiological consequences of LPA signalling are evident and misregulation of LPA signalling can lead to pathologies like cancer, atherosclerosis, ischaemia, and fibrosis. LPA exerts its biological actions mainly through several types of G protein-coupled receptors, some of which display opposing or redundant effects. For this reason, selective LPA receptor small-molecule ligands can shine light on LPA biology and present an exciting opportunity for drug discovery endeavours. This review provides insights into the detailed chemical nature and pharmacological profile of the small-molecules thus far developed as LPA receptor modulators, as well as information on the preparation of key pharmaceuticals. This summary will facilitate future research efforts and nurture collaboration between chemists and biologists working in this emerging field. Copyright © 2015 Elsevier Ltd. All rights reserved.

  13. Lysophosphatidic acid (LPA) signaling in the nervous system

    PubMed Central

    Yung, Yun C.; Stoddard, Nicole C.; Mirendil, Hope; Chun, Jerold

    2015-01-01

    Summary The brain is composed of many lipids with varied forms that serve not only as structural components but also as essential signaling molecules. Lysophosphatidic acid (LPA) is an important bioactive lipid species that is part of the lysophospholipid (LP) family. LPA is primarily derived from membrane phospholipids and signals through six cognate G protein-coupled receptors (GPCRs), LPA1-6. These receptors are expressed on most cell types within central and peripheral nervous tissues and have been functionally linked to many neural processes and pathways. This review covers a current understanding of LPA signaling in the nervous system, with particular focus on the relevance of LPA to both physiological and diseased states. PMID:25695267

  14. Polyunsaturated lysophosphatidic acid as a potential asthma biomarker.

    PubMed

    Ackerman, Steven J; Park, Gye Young; Christman, John W; Nyenhuis, Sharmilee; Berdyshev, Evgeny; Natarajan, Viswanathan

    2016-01-01

    Lysophosphatidic acid (LPA), a lipid mediator in biological fluids and tissues, is generated mainly by autotaxin that hydrolyzes lysophosphatidylcholine to LPA and choline. Total LPA levels are increased in bronchoalveolar lavage fluid from asthmatic lung, and are strongly induced following subsegmental bronchoprovocation with allergen in subjects with allergic asthma. Polyunsaturated molecular species of LPA (C22:5 and C22:6) are selectively synthesized in the airways of asthma subjects following allergen challenge and in mouse models of allergic airway inflammation, having been identified and quantified by LC/MS/MS lipidomics. This review discusses current knowledge of LPA production in asthmatic lung and the potential utility of polyunsaturated LPA molecular species as novel biomarkers in bronchoalveolar lavage fluid and exhaled breath condensate of asthma subjects.

  15. Crystal Structure of Antagonist Bound Human Lysophosphatidic Acid Receptor 1

    PubMed Central

    Chrencik, Jill E.; Roth, Christopher B.; Terakado, Masahiko; Kurata, Haruto; Omi, Rie; Kihara, Yasuyuki; Warshaviak, Dora; Nakade, Shinji; Asmar-Rovira, Guillermo; Mileni, Mauro; Mizuno, Hirotaka; Griffith, Mark T.; Rodgers, Caroline; Han, Gye Won; Velasquez, Jeffrey; Chun, Jerold; Stevens, Raymond C.

    2015-01-01

    Summary Lipid biology continues to emerge as an area of significant therapeutic interest, particularly as the result of an enhanced understanding of the wealth of signaling molecules with diverse physiological properties. This growth in knowledge is epitomized by lysophosphatidic acid (LPA), which functions through interactions with six cognate G protein-coupled receptors. Herein we present three crystal structures of LPA1 in complex with antagonist tool compounds selected and designed through structural and stability analysis. Structural analysis combined with molecular dynamics identified a basis for ligand access to the LPA1 binding pocket from the extracellular space contrasting with the proposed access for the sphingosine 1-phosphate receptor. Characteristics of the LPA1 binding pocket raise the possibility of promiscuous ligand recognition of phosphorylated endocannabinoids. Cell-based assays confirmed this hypothesis, linking the distinct receptor systems through metabolically related ligands with potential functional and therapeutic implications for treatment of disease. PMID:26091040

  16. Lysophosphatidic Acid (LPA) Signaling in Human and Ruminant Reproductive Tract

    PubMed Central

    Wocławek-Potocka, Izabela; Rawińska, Paulina; Kowalczyk-Zieba, Ilona; Boruszewska, Dorota; Sinderewicz, Emilia; Waśniewski, Tomasz; Skarzynski, Dariusz Jan

    2014-01-01

    Lysophosphatidic acid (LPA) through activating its G protein-coupled receptors (LPAR 1–6) exerts diverse cellular effects that in turn influence several physiological processes including reproductive function of the female. Studies in various species of animals and also in humans have identified important roles for the receptor-mediated LPA signaling in multiple aspects of human and animal reproductive tract function. These aspects range from ovarian and uterine function, estrous cycle regulation, early embryo development, embryo implantation, decidualization to pregnancy maintenance and parturition. LPA signaling can also have pathological consequences, influencing aspects of endometriosis and reproductive tissue associated tumors. The review describes recent progress in LPA signaling research relevant to human and ruminant reproduction, pointing at the cow as a relevant model to study LPA influence on the human reproductive performance. PMID:24744506

  17. Isolation of Lysophosphatidic Acid Phosphatase from Developing Peanut Cotyledons1

    PubMed Central

    Shekar, Sunil; Tumaney, Ajay W.; Rao, T.J.V. Sreenivasa; Rajasekharan, Ram

    2002-01-01

    The soluble fraction of immature peanut (Arachis hypogaea) was capable of dephosphorylating [3H]lysophosphatidic acid (LPA) to generate monoacylglycerol (MAG). The enzyme responsible for the generation of MAG, LPA phosphatase, has been identified in plants and purified by successive chromatography separations on octyl-Sepharose, Blue Sepharose, Superdex-75, and heparin-agarose to apparent homogeneity from developing peanuts. This enzyme was purified 5,048-fold to a final specific activity of 858 nmol min−1 mg−1. The enzyme has a native molecular mass of approximately 39 kD determined by gel filtration and migrates as a single band on sodium dodecyl sulfate-polyacrylamide gel electrophoresis with a subunit molecular mass of 39 ± 1.5 kD. The Km values for oleoyl-, stearoyl-, and palmitoyl-sn-glycerol-3-phosphate were determined to be 28.6, 39.3, and 47.9 μm, respectively. The LPA phosphatase was specific to LPA and did not utilize any other substrate such as glycerol-3-phosphate, phosphatidic acid, or p-nitrophenylphosphate. The enzyme activity was stimulated by the low concentrations of detergents such as Triton X-100 and octylglucoside. Cations had no effect on the enzyme activity. Fatty acids, sphingosine, and sphingomyelin at low concentrations stimulated the enzyme activity. The identification of LPA phosphatase in plants demonstrates the existence of MAG biosynthetic machinery in plants. PMID:11891254

  18. Lysophosphatidic acid metabolism and elimination in cardiovascular disease

    NASA Astrophysics Data System (ADS)

    Salous, Abdelghaffar Kamal

    The bioactive lipids lysophosphatidic acid (LPA) and sphingosine 1-phosphate (S1P) are present in human and mouse plasma at a concentration of ~0.1-1 microM and regulate physiological and pathophysiological processes in the cardiovascular system including atherothrombosis, intimal hyperplasia, and immune function, edema formation, and permeability. PPAP2B, the gene encoding LPP3, a broad activity integral membrane enzyme that terminates LPA actions in the vasculature, has a single nucleotide polymorphism that been recently associated with coronary artery disease risk. The synthesis and signaling of LPA and S1P in the cardiovascular system have been extensively studied but the mechanisms responsible for their elimination are less well understood. The broad goal of this research was to examine the role of LPP3 in the termination of LPA signaling in models of cardiovascular disease involving vascular wall cells, investigate the role of LPP3 in the elimination of plasma LPA, and further characterize the elimination of plasma LPA. The central hypothesis is that LPP3 plays an important role in attenuating the pathological responses to LPA signaling and that it mediates the elimination of exogenously applied bioactive lipids from the plasma. These hypotheses were tested using molecular biological approaches, in vitro studies, synthetic lysophospholipid mimetics, modified surgical procedures, and mass spectrometry assays. My results indicated that LPP3 played a critical role in attenuating LPA signaling mediating the pathological processes of intimal hyperplasia and vascular leak in mouse models of disease. Additionally, enzymatic inactivation of lysophospholipids by LPP and PLA enzymes in the plasma was not a primary mechanism for the rapid elimination of plasma LPA and S1P. Instead, evidence strongly suggested a transcellular uptake mechanism by hepatic non-parenchymal cells as the predominant mechanism for elimination of these molecules. These results support a model in

  19. Lysophosphatidic acid induced red blood cell aggregation in vitro.

    PubMed

    Kaestner, Lars; Steffen, Patrick; Nguyen, Duc Bach; Wang, Jue; Wagner-Britz, Lisa; Jung, Achim; Wagner, Christian; Bernhardt, Ingolf

    2012-10-01

    Under physiological conditions healthy RBCs do not adhere to each other. There are indications that RBCs display an intercellular adhesion under certain (pathophysiological) conditions. Therefore we investigated signaling steps starting with transmembrane calcium transport by means of calcium imaging. We found a lysophosphatidic acid (LPA) concentration dependent calcium influx with an EC(50) of 5 μM LPA. Downstream signaling was investigated by flow cytometry as well as by video-imaging comparing LPA induced with "pure" calcium mediated phosphatidylserine exposure and concluded the coexistence of two branches of the signaling pathway. Finally we performed force measurements with holographic optical tweezers (HOT): The intercellular adhesion of RBCs (aggregation) exceeds a force of 25 pN. These results support (i) earlier data of a RBC associated component in thrombotic events under certain pathophysiological conditions and (ii) the concept to use RBCs in studies of cellular adhesion behavior, especially in combination with HOT. The latter paves the way to use RBCs as model cells to investigate molecular regulation of cellular adhesion processes.

  20. Altered food consumption in mice lacking lysophosphatidic acid receptor-1.

    PubMed

    Dusaulcy, R; Daviaud, D; Pradère, J P; Grès, S; Valet, Ph; Saulnier-Blache, J S

    2009-12-01

    The release of lysophosphatidic acid (LPA) by adipocytes has previously been proposed to play a role in obesity and associated pathologies such as insulin resistance and diabetes. In the present work, the sensitivity to diet-induced obesity was studied in mice lacking one of the LPA receptor subtype (LPA1R). Conversely to what was observed in wild type (WT) mice, LPA1R-KO-mice fed a high fat diet (HFD) showed no significant increase in body weight or fat mass when compared to low fat diet (LFD). In addition, in contrast to what was observed in WT mice, LPA1R-KO mice did not exhibit over-consumption of food associated with HFD. Surprisingly, when fed a LFD, LPA1R-KO mice exhibited significant higher plasma leptin concentration and higher level of adipocyte leptin mRNA than WT mice. In conclusion, LPA1R-KO mice were found to be resistant to diet-induced obesity consecutive to a resistance to fat-induced over-consumption of food that may result at least in part from alterations in leptin expression and production.

  1. Pharmacological activation of lysophosphatidic acid receptors regulates erythropoiesis.

    PubMed

    Lin, Kuan-Hung; Ho, Ya-Hsuan; Chiang, Jui-Chung; Li, Meng-Wei; Lin, Shi-Hung; Chen, Wei-Min; Chiang, Chi-Ling; Lin, Yu-Nung; Yang, Ya-Jan; Chen, Chiung-Nien; Lu, Jenher; Huang, Chang-Jen; Tigyi, Gabor; Yao, Chao-Ling; Lee, Hsinyu

    2016-05-31

    Lysophosphatidic acid (LPA), a growth factor-like phospholipid, regulates numerous physiological functions, including cell proliferation and differentiation. In a previous study, we have demonstrated that LPA activates erythropoiesis by activating the LPA 3 receptor subtype (LPA3) under erythropoietin (EPO) induction. In the present study, we applied a pharmacological approach to further elucidate the functions of LPA receptors during red blood cell (RBC) differentiation. In K562 human erythroleukemia cells, knockdown of LPA2 enhanced erythropoiesis, whereas knockdown of LPA3 inhibited RBC differentiation. In CD34(+) human hematopoietic stem cells (hHSC) and K526 cells, the LPA3 agonist 1-oleoyl-2-methyl-sn-glycero-3-phosphothionate (2S-OMPT) promoted erythropoiesis, whereas the LPA2 agonist dodecyl monophosphate (DMP) and the nonlipid specific agonist GRI977143 (GRI) suppressed this process. In zebrafish embryos, hemoglobin expression was significantly increased by 2S-OMPT treatment but was inhibited by GRI. Furthermore, GRI treatment decreased, whereas 2S-OMPT treatment increased RBC counts and amount of hemoglobin level in adult BALB/c mice. These results indicate that LPA2 and LPA3 play opposing roles during RBC differentiation. The pharmacological activation of LPA receptor subtypes represent a novel strategies for augmenting or inhibiting erythropoiesis.

  2. Pharmacological activation of lysophosphatidic acid receptors regulates erythropoiesis

    PubMed Central

    Lin, Kuan-Hung; Ho, Ya-Hsuan; Chiang, Jui-Chung; Li, Meng-Wei; Lin, Shi-Hung; Chen, Wei-Min; Chiang, Chi-Ling; Lin, Yu-Nung; Yang, Ya-Jan; Chen, Chiung-Nien; Lu, Jenher; Huang, Chang-Jen; Tigyi, Gabor; Yao, Chao-Ling; Lee, Hsinyu

    2016-01-01

    Lysophosphatidic acid (LPA), a growth factor-like phospholipid, regulates numerous physiological functions, including cell proliferation and differentiation. In a previous study, we have demonstrated that LPA activates erythropoiesis by activating the LPA 3 receptor subtype (LPA3) under erythropoietin (EPO) induction. In the present study, we applied a pharmacological approach to further elucidate the functions of LPA receptors during red blood cell (RBC) differentiation. In K562 human erythroleukemia cells, knockdown of LPA2 enhanced erythropoiesis, whereas knockdown of LPA3 inhibited RBC differentiation. In CD34+ human hematopoietic stem cells (hHSC) and K526 cells, the LPA3 agonist 1-oleoyl-2-methyl-sn-glycero-3-phosphothionate (2S-OMPT) promoted erythropoiesis, whereas the LPA2 agonist dodecyl monophosphate (DMP) and the nonlipid specific agonist GRI977143 (GRI) suppressed this process. In zebrafish embryos, hemoglobin expression was significantly increased by 2S-OMPT treatment but was inhibited by GRI. Furthermore, GRI treatment decreased, whereas 2S-OMPT treatment increased RBC counts and amount of hemoglobin level in adult BALB/c mice. These results indicate that LPA2 and LPA3 play opposing roles during RBC differentiation. The pharmacological activation of LPA receptor subtypes represent a novel strategies for augmenting or inhibiting erythropoiesis. PMID:27244685

  3. Challenges in accurate quantitation of lysophosphatidic acids in human biofluids

    PubMed Central

    Onorato, Joelle M.; Shipkova, Petia; Minnich, Anne; Aubry, Anne-Françoise; Easter, John; Tymiak, Adrienne

    2014-01-01

    Lysophosphatidic acids (LPAs) are biologically active signaling molecules involved in the regulation of many cellular processes and have been implicated as potential mediators of fibroblast recruitment to the pulmonary airspace, pointing to possible involvement of LPA in the pathology of pulmonary fibrosis. LPAs have been measured in various biological matrices and many challenges involved with their analyses have been documented. However, little published information is available describing LPA levels in human bronchoalveolar lavage fluid (BALF). We therefore conducted detailed investigations into the effects of extensive sample handling and sample preparation conditions on LPA levels in human BALF. Further, targeted lipid profiling of human BALF and plasma identified the most abundant lysophospholipids likely to interfere with LPA measurements. We present the findings from these investigations, highlighting the importance of well-controlled sample handling for the accurate quantitation of LPA. Further, we show that chromatographic separation of individual LPA species from their corresponding lysophospholipid species is critical to avoid reporting artificially elevated levels. The optimized sample preparation and LC/MS/MS method was qualified using a stable isotope-labeled LPA as a surrogate calibrant and used to determine LPA levels in human BALF and plasma from a Phase 0 clinical study comparing idiopathic pulmonary fibrosis patients to healthy controls. PMID:24872406

  4. Lysophosphatidic acid mediates pleiotropic responses in skeletal muscle cells

    SciTech Connect

    Jean-Baptiste, Gael; Yang Zhao; Khoury, Chamel; Greenwood, Michael T.; E-mail: michael.greenwood@mcgill.ca

    2005-10-07

    Lysophosphatidic acid (LPA) is a potent modulator of growth, cell survival, and apoptosis. Although all four LPA receptors are expressed in skeletal muscle, very little is known regarding the role they play in this tissue. We used RT-PCR to demonstrate that cultured skeletal muscle C2C12 cells endogenously express multiple LPA receptor subtypes. The demonstration that LPA mediates the activation of ERK1/2 MAP kinase and Akt/PKB in C2C12 cells is consistent with the widely observed mitogenic properties of LPA. In spite of these observations, LPA did not induce proliferation in C2C12 cells. Paradoxically, we found that prolonged treatment of C2C12 cells with LPA led to caspase 3 and PARP cleavage as well as the activation of stress-associated MAP kinases JNK and p38. In spite of these typically pro-apoptotic responses, LPA did not induce cell death. Blocking ERK1/2 and Akt/PKB activation with specific pharmacological inhibitors, nevertheless, stimulated LPA-mediated apoptosis. Taken together, these results suggest that both mitogenic and apoptotic responses serve to counterbalance the effects of LPA in cultured C2C12 cells.

  5. Lysophosphatidic acid targets vascular and oncogenic pathways via RAGE signaling

    PubMed Central

    Touré, Fatouma; Chitayat, Seth; Pei, Renjun; Song, Fei; Li, Qing; Zhang, Jinghua; Rosario, Rosa; Ramasamy, Ravichandran; Chazin, Walter J.

    2012-01-01

    The endogenous phospholipid lysophosphatidic acid (LPA) regulates fundamental cellular processes such as proliferation, survival, motility, and invasion implicated in homeostatic and pathological conditions. Hence, delineation of the full range of molecular mechanisms by which LPA exerts its broad effects is essential. We report avid binding of LPA to the receptor for advanced glycation end products (RAGE), a member of the immunoglobulin superfamily, and mapping of the LPA binding site on this receptor. In vitro, RAGE was required for LPA-mediated signal transduction in vascular smooth muscle cells and C6 glioma cells, as well as proliferation and migration. In vivo, the administration of soluble RAGE or genetic deletion of RAGE mitigated LPA-stimulated vascular Akt signaling, autotaxin/LPA-driven phosphorylation of Akt and cyclin D1 in the mammary tissue of transgenic mice vulnerable to carcinogenesis, and ovarian tumor implantation and development. These findings identify novel roles for RAGE as a conduit for LPA signaling and suggest targeting LPA–RAGE interaction as a therapeutic strategy to modify the pathological actions of LPA. PMID:23209312

  6. Lysophosphatidic acid possesses dual action in cell proliferation.

    PubMed Central

    Tigyi, G; Dyer, D L; Miledi, R

    1994-01-01

    Lysophosphatidic acid (LPA) induces mitogenic responses in cultured fibroblasts through a pertussis toxin-sensitive signaling pathway. In contrast, we have shown that LPA inhibits the proliferation of Sp2/0-Ag14 myeloma cells. To resolve this apparent controversy, LPA-elicited responses in cell proliferation and the underlying second messenger mechanisms were compared in Sp2/0-Ag14 myeloma and NIH 3T3 fibroblast cells. The antimitogenic response was not elicited by micromolar concentrations of phosphatidic acid, phosphatidylglycerol, or diacylglycerol. In NIH 3T3 and Sp2 cells, LPA elicited an increase in inositol trisphosphate and a subsequent transient increase in free cytoplasmic Ca2+. Unlike the mitogenic response in NIH 3T3 cells, the antimitogenic effect was not affected by pertussis toxin; on the contrary, it was accompanied by an increase in cAMP. In Sp2 cells, cAMP analogs, forskolin, and isobutylmethylxanthine inhibited cell proliferation and enhanced LPA action in an additive manner, suggesting that an LPA-elicited increase in cAMP-mediated signaling was responsible for the antimitogenic response. In addition to the mitogenic response in fibroblasts and the antimitogenic response in tumor cell lines, there are some cell types (Jurkat T-cell lymphoma and primary astrocytes) in which LPA is ineffective in altering cell proliferation. The cell-type-specific dual action of LPA suggests that this endogenous lipid mediator when released from activated cells might play an important role as a regulator, rather than a ubiquitous inducer, of cell proliferation. Images PMID:8127904

  7. Autotaxin Production of Lysophosphatidic Acid Mediates Allergic Asthmatic Inflammation

    PubMed Central

    Park, Gye Young; Lee, Yong Gyu; Berdyshev, Evgeny; Nyenhuis, Sharmilee; Du, Jian; Fu, Panfeng; Gorshkova, Irina A.; Li, Yongchao; Chung, Sangwoon; Karpurapu, Manjula; Deng, Jing; Ranjan, Ravi; Xiao, Lei; Jaffe, H. Ari; Corbridge, Susan J.; Kelly, Elizabeth A. B.; Jarjour, Nizar N.; Chun, Jerold; Prestwich, Glenn D.; Kaffe, Eleanna; Ninou, Ioanna; Aidinis, Vassilis; Morris, Andrew J.; Smyth, Susan S.; Ackerman, Steven J.; Natarajan, Viswanathan

    2013-01-01

    Rationale: Bioactive lipid mediators, derived from membrane lipid precursors, are released into the airway and airspace where they bind high-affinity cognate receptors and may mediate asthma pathogenesis. Lysophosphatidic acid (LPA), a bioactive lipid mediator generated by the enzymatic activity of extracellular autotaxin (ATX), binds LPA receptors, resulting in an array of biological actions on cell proliferation, migration, survival, differentiation, and motility, and therefore could mediate asthma pathogenesis. Objectives: To define a role for the ATX-LPA pathway in human asthma pathogenesis and a murine model of allergic lung inflammation. Methods: We investigated the profiles of LPA molecular species and the level of ATX exoenzyme in bronchoalveolar lavage fluids of human patients with asthma subjected to subsegmental bronchoprovocation with allergen. We interrogated the role of the ATX-LPA pathway in allergic lung inflammation using a murine allergic asthma model in ATX-LPA pathway–specific genetically modified mice. Measurements and Main Results: Subsegmental bronchoprovocation with allergen in patients with mild asthma resulted in a remarkable increase in bronchoalveolar lavage fluid levels of LPA enriched in polyunsaturated 22:5 and 22:6 fatty acids in association with increased concentrations of ATX protein. Using a triple-allergen mouse asthma model, we showed that ATX-overexpressing transgenic mice had a more severe asthmatic phenotype, whereas blocking ATX activity and knockdown of the LPA2 receptor in mice produced a marked attenuation of Th2 cytokines and allergic lung inflammation. Conclusions: The ATX-LPA pathway plays a critical role in the pathogenesis of asthma. These preclinical data indicate that targeting the ATX-LPA pathway could be an effective antiasthma treatment strategy. PMID:24050723

  8. Lysophosphatidic Acid Protects Against Endotoxin-Induced Acute Kidney Injury.

    PubMed

    Mirzoyan, Koryun; Denis, Colette; Casemayou, Audrey; Gilet, Marion; Marsal, Dimitri; Goudounéche, Dominique; Faguer, Stanislas; Bascands, Jean-Loup; Schanstra, Joost P; Saulnier-Blache, Jean-Sébastien

    2017-06-30

    Septic shock is the most common cause of acute kidney injury (AKI), but the underlying mechanisms remain unclear and no targeted therapies exist. Lysophosphatidic acid (LPA) is a bioactive lipid which in vivo administration was reported to mitigate inflammation and injuries caused by bacterial endotoxemia in the liver and lung. The objective of the present study was to determine whether LPA can protect against sepsis-associated AKI. C57BL/6 mice were treated with LPA 18:1 (5 mg/kg, i.p.) 1 h before being injected with the endotoxin lipopolysaccharide (LPS), and AKI was evaluated after 24 h. LPA significantly decreased the elevation of plasma urea and creatinine caused by LPS. In the kidney, LPA pretreatment significantly reduced the upregulation of inflammatory cytokines (IL-6, TNFα, monocyte chemoattractant protein-1 (MCP-1)), and completely prevented downregulation of peroxisome proliferator-activated receptor gamma coactivator 1-alpha and upregulation of heme oxygenase-1 caused by LPS. LPA also prevented LPS-mediated alterations of the renal mitochondrial ultrastructure. In vitro pretreatment with LPA 18:1 significantly attenuated LPS-induced upregulation of the inflammatory cytokines (TNFα and MCP-1) in RAW264 macrophages. Moreover, in vivo LPS treatment lowered urinary LPA concentration and reduced LPA anabolic enzymes (autotaxin and acylglycerol kinase), and increased the LPA catalytic enzyme (lipid phosphate phosphatase 2) expression in the kidney cortex. In conclusion, exogenous LPA exerted a protective action against renal inflammation and injuries caused by bacterial endotoxemia. Moreover, LPS reduces the renal production of LPA suggesting that sepsis-associated AKI could be mediated, at least in part, by alleviation of the protective action of endogenous LPA.

  9. Lysophosphatidic acids. Influence on platelet aggregation and intracellular calcium flux.

    PubMed Central

    Gerrard, J. M.; Kindom, S. E.; Peterson, D. A.; Peller, J.; Krantz, K. E.; White, J. G.

    1979-01-01

    Decanoyl-, palmitoyl-, and oleoyl-lysophosphatidic acid (LPA) were studied for their effects on platelet aggregation and intracellular calcium flux. Palmitoyl-LPA and oleoyl-LPA both caused a concentration-dependent aggregation of human blood platelets at concentrations of 12--300 microM. Aggregation by adenosine diphosphate (ADP) was enhanced at slightly lower concentrations. First-wave aggregation induced by these LPAs was not blocked by aspirin, indomethacin, or heparin, suggesting similarities to ADP aggregation. However, in washed platelets with a high calcium concentration, no serotonin secretion was observed, even though full aggregation occurred, suggesting that aggregation was not due to released ADP. This concept was supported by studies of platelets deficient in the storage pool of ADP and serotonin, which had a normal first-wave aggregation response to palmitoyl-LPA. Aggregation induced by palmitoyl LPA was inhibited by prostaglandin E1 (PGE1), theophylline, and ethylenediaminotetraacetate (EDTA), though in the presence of EDTA shape change occurred. Aggregation stimulated by palmitoyl-LPA or oleoyl-LPA was characterized by changes in the shape of the platelets with development of pseudopods and centralization of granules closely surrounded by contractile microfilaments and supporting microtubules. The addition of palmitoyl-LPA and oleoyl-LPA, but not decanoyl-LPA, caused the release of calcium from a platelet membrane fraction that contains elements of the intracellular calcium storage system and actively concentrates this cation in the presence of adenosine triphosphate (ATP) and magnesium. It is suggested that LPAs cause aggregation by stimulating the release of calcium intracellularly. Images Figure 1 Figure 2 Figure 3 Figure 4 Text-Figure 6 PMID:112871

  10. Regulation of silicosis formation by lysophosphatidic acid and its receptors.

    PubMed

    Cong, Cuicui; Mao, Lijun; Zhang, Yanlin; Zhao, Zanmei; Xu, Xixian; Zhao, Jinyuan

    2014-09-01

    Silicosis is a serious occupational disease characterized by lung fibrosis that is caused by long-term inhalation of silica-containing fine particles. Lysophosphatidic acid (LPA) and LPA1/3 plays a role in lung fibrosis. Until recently, there has been little research investigating the role of LPA and LPA receptors (LPAR) in silica-induced development of pulmonary fibrosis. In this study, we evaluated the hypothesis that LPA and LPA1/3 may play a role in silicosis pathogenesis using rat silicosis models induced by intratracheal instillation of silica, and randomly divided into control, silica, and VPC-12249 groups. LPA serum and bronchoalveolar lavage fluid (BALF) levels were quantified by ELISA. α-smooth muscle actin (α-SMA), type I and III collagen protein expression was quantified by western blotting (WB), and type I and III collagen mRNAs detected by reverse transcriptase-polymerase chain reaction (RT-PCR). Lung hydroxyproline (HYP) levels were detected using alkaline hydrolysis, with hematoxylin and eosin (H&E) and picrosirius red staining used for pathological examination. In vitro experiments showed that LPA stimulated fibroblasts proliferated in a time and dose-dependent manner and promoted expression of α-SMA, and type I and III collagen. Moreover, LPA serum and BALF levels increased in silica-instilled rats. In vivo and in vitro experiments revealed that α-SMA expression and collagen deposition reduced significantly after VPC-12249 treatment, and histopathological results show VPC-12249 alleviates silicosis progression. In conclusion, our findings suggest that LPA promotes the proliferation, transformation, and collagen synthesis of fibroblasts, and that LPA-LPA1/3 are involved in the development of silicosis and may serve as novel therapeutic targets for treatment.

  11. A New Anti-Aging Lysophosphatidic Acid from Arabidopsis thaliana.

    PubMed

    Sun, Yujuan; Wang, Yanhui; Wang, Guangfa; Xiang, Lan; Qi, Jianhua

    2017-02-09

    Aging is a risk factor of age-related diseases. With the increasing number of patients, serious consequences, and heavy economic burden, demands for drugs used to treat age-related diseases have increased. As such, anti-aging substances should be isolated to develop drugs for the prevention and treatment of age-related diseases. In this study, a methanol extract of immature Arabidopsis thaliana seeds with coat was separated by using a K6001 yeast bioassay system. In order to investigate the action mechanism, four mutants, namely, Δuth1, Δskn7, Δsod1, and Δsod2 with K6001 background were employed and the anti-oxidative stress assay was performed. One new anti-aging lysophosphatidic acid (LPA) was obtained, and its structural and stereochemical characteristics were elucidated through spectroscopy and chemical derivatization. LPA can extend the replicative lifespan of K6001 at 10 and 30 µM (p < 0.001 and p < 0.01, respectively). This finding was comparable to the effect of resveratrol, a well-known anti-aging substance. However, the anti-aging activity of the compound on the four mutants was diminished. In the anti-oxidative stress assay, LPA improved the oxidative resistance of yeast cells. The new LPA may exert its anti-aging effect by improving the anti-oxidative ability of yeast cells. The genes of UTH1, SKN7, and SOD may also be involved in the action. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

  12. Lysophosphatidic acid (LPA) as a pro-fibrotic and pro-oncogenic factor: a pivotal target to improve the radiotherapy therapeutic index.

    PubMed

    Rancoule, Chloé; Espenel, Sophie; Trone, Jane-Chloé; Langrand-Escure, Julien; Vallard, Alexis; Rehailia-Blanchard, Amel; El Meddeb Hamrouni, Anis; Xia, Yaxiong; Guy, Jean-Baptiste; Ben-Mrad, Majed; Magné, Nicolas

    2017-06-27

    Radiation-induced fibrosis is widely considered as a common but forsaken phenomenon that can lead to clinical sequela and possibly vital impairments. Lysophosphatidic acid is a bioactive lipid involved in fibrosis and probably in radiation-induced fibrosis as suggested in recent studies. Lysophosphatidic acid is also a well-described pro-oncogenic factor, involved in carcinogenesis processes (proliferation, survival, angiogenesis, invasion, migration). The present review highlights and summarizes the links between lysophosphatidic acid and radiation-induced fibrosis, lysophosphatidic acid and radioresistance, and proposes lysophosphatidic acid as a potential central actor of the radiotherapy therapeutic index. Besides, we hypothesize that following radiotherapy, the newly formed tumour micro-environment, with increased extracellular matrix and increased lysophosphatidic acid levels, is a favourable ground to metastasis development. Lysophosphatidic acid could therefore be an exciting therapeutic target, minimizing radio-toxicities and radio-resistance effects.

  13. Lysophosphatidic acid (LPA) as a pro-fibrotic and pro-oncogenic factor: a pivotal target to improve the radiotherapy therapeutic index

    PubMed Central

    Rancoule, Chloé; Espenel, Sophie; Trone, Jane-Chloé; Langrand-Escure, Julien; Vallard, Alexis; Rehailia-Blanchard, Amel; Hamrouni, Anis El Meddeb; Xia, Yaxiong; Guy, Jean-Baptiste; Ben-Mrad, Majed; Magné, Nicolas

    2017-01-01

    Radiation-induced fibrosis is widely considered as a common but forsaken phenomenon that can lead to clinical sequela and possibly vital impairments. Lysophosphatidic acid is a bioactive lipid involved in fibrosis and probably in radiation-induced fibrosis as suggested in recent studies. Lysophosphatidic acid is also a well-described pro-oncogenic factor, involved in carcinogenesis processes (proliferation, survival, angiogenesis, invasion, migration). The present review highlights and summarizes the links between lysophosphatidic acid and radiation-induced fibrosis, lysophosphatidic acid and radioresistance, and proposes lysophosphatidic acid as a potential central actor of the radiotherapy therapeutic index. Besides, we hypothesize that following radiotherapy, the newly formed tumour micro-environment, with increased extracellular matrix and increased lysophosphatidic acid levels, is a favourable ground to metastasis development. Lysophosphatidic acid could therefore be an exciting therapeutic target, minimizing radio-toxicities and radio-resistance effects. PMID:28402936

  14. Lysophosphatidic acid-induced chemotaxis of bone cells.

    SciTech Connect

    Karagiosis, Sue A.; Masiello, Lisa M.; Bollinger, Nikki; Karin, Norm J.

    2006-07-01

    Lysophosphatidic acid (LPA) is a platelet-derived bioactive lipid that is postulated to regulate wound healing. LPA activates G protein-coupled receptors to induce Ca2+ signaling in MC3T3-E1 pre-osteoblasts, and is a potent chemotactic stimulus for these cells. Since bone fracture healing requires the migration of osteoblast progenitors, we postulate that LPA is among the factors that stimulate bone repair. UMR 106-01 cells, which express a more mature osteoblastic phenotype than MC3T3-E1 cells, did not migrate in response to LPA, although they express LPA receptors and exhibit LPA-induced Ca2+ signals. This suggests that LPA differentially induces pre-osteoblast chemotaxis, consistent with our hypothesis that LPA stimulates the motility of osteoblast progenitors during bone healing. LPA-stimulated MC3T3-E1 cells exhibit striking changes in morphology and F-actin architecture, and phosphatidylinositol-3 kinase (PI3K) is required for motility-associated cytoskeletal rearrangements in many cell types. We found a dose-dependent reduction in LPA-induced osteoblast migration when cells also were treated with the PI3K inhibitor, LY294002. Treatment of many cell types with LPA is associated with an autocrine/paracrine transactivation of the EGF receptor (EGFR) via shedding of surface-tethered EGFR ligands, a phenomenon often required for LPA-induced chemotaxis. MC3T3-E1 cells express multiple EGFR ligands (epigen, epiregulin, HB-EGF and amphiregulin) and migrated in response to EGF. However, while EGF-stimulated motility in MC3T3-E1 cells was blocked by an EGFR inhibitor, there was no significant effect on LPA-induced chemotaxis. Activation of MAP kinases is a hallmark of EGFR-mediated signaling, and EGF treatment of MC3T3-E1 cells led to a strong stimulation of ERK1/2 kinase. In contrast, LPA induced only a minor elevation in ERK activity. Thus, it is likely that the increase in ERK activity by LPA is related to cell proliferation associated with lipid treatment. We

  15. Iontophoresis of lysophosphatidic acid into rabbit cornea induces HSV-1 reactivation: evidence that neuronal signaling changes after infection.

    PubMed

    Martin, R E; Loutsch, J M; Garza, H H; Boedeker, D J; Hill, J M

    1999-12-20

    Lysophosphatidic acid induces neurite retraction; it is also present in tears and aqueous humor. We determined whether lysophosphatidic acid induces HSV-1 reactivation in latently infected rabbits and whether the nerve growth associated protein GAP-43 undergoes posttranslational modification during the course of HSV-1 infection. Rabbits were infected with HSV-1 and acute infection was documented by slit lamp examination. Corneas of latently infected rabbits were treated with lysophosphatidic acid or lysophosphatidylserine (structurally similar but lacking biological potency). For application to the cornea, these compounds were impregnated into collagen shields, applied as topical drops, or iontophoresed. In another experiment, corneas of latently infected rabbits were either untreated or treated iontophoretically with lysophosphatidic acid, lysophosphatidylserine, or saline. Ocular swabs detected shedding of infectious virus. Western blot and immunoprecipitation identified GAP-43 in corneal extracts and densitometry of silver-stained isoelectric focusing gels measured changes in GAP-43 isoform abundance. Iontophoresis of lysophosphatidic acid induced HSV-1 shedding more frequently than lysophosphatidylserine or saline. Viral shedding induced by collagen shield and topical drop administration was low and not significantly different for lysophosphatidic acid and lysophosphatidylserine. Five discrete GAP-43 isoforms predominated in the IEF gels. Most abundant were the pI 4.7 band in uninfected cornea and the pI 5.05 band in latently-infected cornea. Compared to latently-infected cornea, there was no significant change in isoform abundance 1 h after lysophosphatidic acid iontophoresis, but 24 and 72 h later, the pI 5. 05 band was diminished. Lysophosphatidic acid can induce HSV-1 reactivation and changes in GAP-43 pI suggest that posttranslational modifications, possibly related to phosphorylation and ADP-ribosylation, are occurring during HSV-1 latency and after LPA

  16. Activation of fibroblast-like synoviocytes derived from rheumatoid arthritis via lysophosphatidic acid-lysophosphatidic acid receptor 1 cascade.

    PubMed

    Miyabe, Yoshishige; Miyabe, Chie; Iwai, Yoshiko; Yokoyama, Waka; Sekine, Chiyoko; Sugimoto, Kazutaka; Harigai, Masayoshi; Miyasaka, Masayuki; Miyasaka, Nobuyuki; Nanki, Toshihiro

    2014-10-02

    Lysophosphatidic acid (LPA) is a bioactive lipid that binds to G protein-coupled receptors (LPA1-6). Recently, we reported that abrogation of LPA receptor 1 (LPA1) ameliorated murine collagen-induced arthritis, probably via inhibition of inflammatory cell migration, Th17 differentiation and osteoclastogenesis. In this study, we examined the importance of the LPA-LPA1 axis in cell proliferation, cytokine/chemokine production and lymphocyte transmigration in fibroblast-like synoviocytes (FLSs) obtained from the synovial tissues of rheumatoid arthritis (RA) patients. FLSs were prepared from synovial tissues of RA patients. Expression of LPA1-6 was examined by quantitative real-time RT-PCR. Cell surface LPA1 expression was analyzed by flow cytometry. Cell proliferation was analyzed using a cell-counting kit. Production of interleukin 6 (IL-6), vascular endothelial growth factor (VEGF), chemokine (C-C motif) ligand 2 (CCL2), metalloproteinase 3 (MMP-3) and chemokine (C-X-C motif) ligand 12 (CXCL12) was measured by enzyme-linked immunosorbent assay. Pseudoemperipolesis was evaluated using a coculture of RA FLSs and T or B cells. Cell motility was examined by scrape motility assay. Expression of adhesion molecules was determined by flow cytometry. The expression of LPA1 mRNA and cell surface LPA1 was higher in RA FLSs than in FLSs from osteoarthritis tissue. Stimulation with LPA enhanced the proliferation of RA FLSs and the production of IL-6, VEGF, CCL2 and MMP-3 by FLSs, which were suppressed by an LPA1 inhibitor (LA-01). Ki16425, another LPA1 antagonist, also suppressed IL-6 production by LPA-stimulated RA FLSs. However, the production of CXCL12 was not altered by stimulation with LPA. LPA induced the pseudoemperipolesis of T and B cells cocultured with RA FLSs, which was suppressed by LPA1 inhibition. In addition, LPA enhanced the migration of RA FLSs and expression of vascular cell adhesion molecule and intercellular adhesion molecule on RA FLSs, which were also

  17. Lysophosphatidic acids are new substrates for the phosphatase domain of soluble epoxide hydrolase[S

    PubMed Central

    Oguro, Ami; Imaoka, Susumu

    2012-01-01

    Soluble epoxide hydrolase (sEH) is a bifunctional enzyme that has a C-terminus epoxide hydrolase domain and an N-terminus phosphatase domain. The endogenous substrates of epoxide hydrolase are known to be epoxyeicosatrienoic acids, but the endogenous substrates of the phosphatase activity are not well understood. In this study, to explore the substrates of sEH, we investigated the inhibition of the phosphatase activity of sEH toward 4-methylumbelliferyl phosphate by using lecithin and its hydrolyzed products. Although lecithin itself did not inhibit the phosphatase activity, the hydrolyzed lecithin significantly inhibited it, suggesting that lysophospholipid or fatty acid can inhibit it. Next, we investigated the inhibition of phosphatase activity by lysophosphatidyl choline, palmitoyl lysophosphatidic acid, monopalmitoyl glycerol, and palmitic acid. Palmitoyl lysophosphatidic acid and fatty acid efficiently inhibited phosphatase activity, suggesting that lysophosphatidic acids (LPAs) are substrates for the phosphatase activity of sEH. As expected, palmitoyl, stearoyl, oleoyl, and arachidonoyl LPAs were efficiently dephosphorylated by sEH (Km, 3–7 μM; Vmax, 150–193 nmol/min/mg). These results suggest that LPAs are substrates of sEH, which may regulate physiological functions of cells via their metabolism. PMID:22217705

  18. Detection of Serum Lysophosphatidic Acids Using Affinity Binding and Surface Enhanced Laser Desorption/Ionization (SELDI) Time of Flight Mass Spectrometry

    DTIC Science & Technology

    2005-04-01

    Mills G.B., 2004 Lysophosphatidic acid production and action: Validated targets in cancer. J. Cellular Biochemistry 2004 Aug 15;92(6):1115-40. Tanaka T...Lysophosphatidic acid production and action: Validated targets in cancer. J. Cellular Biochemistry 2004 Aug 15;92(6):1115-40. Desmaret, S., Qian, L...0139 13 Journal of Cellular Biochemistry 92:1115-1140 (2004) Lysophosphatidic Acid Production and Action: Validated Targets in Cancer? Makiko Umezu-Goto

  19. Inhibitory role of polyunsaturated fatty acids on lysophosphatidic acid-induced cancer cell migration and adhesion.

    PubMed

    Kim, Eun Kyoung; Ha, Jung Min; Kim, Young Whan; Jin, Seo Yeon; Ha, Hong Koo; Bae, Sun Sik

    2014-08-25

    Polyunsaturated fatty acids (PUFAs) have important pharmacological effects on mammalian cells. Here, we show that carboxyl group-containing PUFAs inhibit lysophosphatidic acid (LPA)-induced focal adhesion formation, thereby inhibiting migration and adhesion. Carboxyl group-containing PUFAs inhibit LPA-induced calcium mobilization, whereas ethyl ester-group containing PUFAs have no effect. In addition, carboxyl group-containing PUFAs functionally inhibit LPA-dependent RhoA activation. Given these results, we suggest that PUFAs may inhibit LPA-induced calcium/RhoA signaling pathways leading to focal adhesion formation. Carboxyl group-containing PUFAs may have a functional role in this regulatory mechanism. Copyright © 2014 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.

  20. Coexpressing Escherichia coli cyclopropane synthase with Sterculia foetida Lysophosphatidic acid acyltransferase enhances cyclopropane fatty acid accumulation.

    PubMed

    Yu, Xiao-Hong; Prakash, Richa Rawat; Sweet, Marie; Shanklin, John

    2014-01-01

    Cyclopropane fatty acids (CPAs) are desirable as renewable chemical feedstocks for the production of paints, plastics, and lubricants. Toward our goal of creating a CPA-accumulating crop, we expressed nine higher plant cyclopropane synthase (CPS) enzymes in the seeds of fad2fae1 Arabidopsis (Arabidopsis thaliana) and observed accumulation of less than 1% CPA. Surprisingly, expression of the Escherichia coli CPS gene resulted in the accumulation of up to 9.1% CPA in the seed. Coexpression of a Sterculia foetida lysophosphatidic acid acyltransferase (SfLPAT) increases CPA accumulation up to 35% in individual T1 seeds. However, seeds with more than 9% CPA exhibit wrinkled seed morphology and reduced size and oil accumulation. Seeds with more than 11% CPA exhibit strongly decreased seed germination and establishment, and no seeds with CPA more than 15% germinated. That previous reports suggest that plant CPS prefers the stereospecific numbering (sn)-1 position whereas E. coli CPS acts on sn-2 of phospholipids prompted us to investigate the preferred positions of CPS on phosphatidylcholine (PC) and triacylglycerol. Unexpectedly, in planta, E. coli CPS acts primarily on the sn-1 position of PC; coexpression of SfLPAT results in the incorporation of CPA at the sn-2 position of lysophosphatidic acid. This enables a cycle that enriches CPA at both sn-1 and sn-2 positions of PC and results in increased accumulation of CPA. These data provide proof of principle that CPA can accumulate to high levels in transgenic seeds and sets the stage for the identification of factors that will facilitate the movement of CPA from PC into triacylglycerol to produce viable seeds with additional CPA accumulation.

  1. Crystal Structure of Autotaxin, a Lysophospholipase D that Produces Lipid Mediator Lysophosphatidic Acids

    NASA Astrophysics Data System (ADS)

    Nishimasu, Hiroshi; Takagi, Junichi; Aoki, Junken; Nureki, Osamu

    Autotaxin (ATX), also known as Enpp2, is a secreted lysophospholipase D that hydrolyzes lysophosphatidylcholine to generate lysophosphatidic acid (LPA), a lipid mediator that activates G-protein coupled receptors to evoke various cellular responses. We solved the crystal structures of mouse ATX alone and in complex with LPAs with different acyl-chain lengths and saturations. The structures reveal a multidomain architecture that may maintain the structure of the hydrophobic pocket, in which the respective LPA molecules are accommodated in distinct conformations. Moreover, our data suggest that the produced LPAs are transferred from the catalytic pocket to cognate receptors through a hydrophobic channel.

  2. Crystal structures and biochemical studies of human lysophosphatidic acid phosphatase type 6.

    PubMed

    Li, Jun; Dong, Yu; Lü, Xingru; Wang, Lu; Peng, Wei; Zhang, Xuejun C; Rao, Zihe

    2013-07-01

    Lysophosphatidic acid (LPA) is an important bioactive phospholipid involved in cell signaling through Gprotein-coupled receptors pathways. It is also involved in balancing the lipid composition inside the cell, and modulates the function of lipid rafts as an intermediate in phospholipid metabolism. Because of its involvement in these important processes, LPA degradation needs to be regulated as precisely as its production. Lysophosphatidic acid phosphatase type 6 (ACP6) is an LPA-specific acid phosphatase that hydrolyzes LPA to monoacylglycerol (MAG) and phosphate. Here, we report three crystal structures of human ACP6 in complex with malonate, L-(+)-tartrate and tris, respectively. Our analyses revealed that ACP6 possesses a highly conserved Rossmann-foldlike body domain as well as a less conserved cap domain. The vast hydrophobic substrate-binding pocket, which is located between those two domains, is suitable for accommodating LPA, and its shape is different from that of other histidine acid phosphatases, a fact that is consistent with the observed difference in substrate preferences. Our analysis of the binding of three molecules in the active site reveals the involvement of six conserved and crucial residues in binding of the LPA phosphate group and its catalysis. The structure also indicates a water-supplying channel for substrate hydrolysis. Our structural data are consistent with the fact that the enzyme is active as a monomer. In combination with additional mutagenesis and enzyme activity studies, our structural data provide important insights into substrate recognition and the mechanism for catalytic activity of ACP6.

  3. Identification of Darmstoff analogs as selective agonists and antagonists of lysophosphatidic acid receptors.

    PubMed

    Gududuru, Veeresa; Zeng, Kui; Tsukahara, Ryoko; Makarova, Natalia; Fujiwara, Yuko; Pigg, Kathryn R; Baker, Daniel L; Tigyi, Gabor; Miller, Duane D

    2006-01-15

    Darmstoff describes a family of gut smooth muscle-stimulating acetal phosphatidic acids initially isolated and characterized from the bath fluid of stimulated gut over 50 years ago. Despite similar structural and biological profiles, Darmstoff analogs have not previously been examined as potential LPA mimetics. Here, we report a facile method for the synthesis of potassium salts of Darmstoff analogs. To understand the effect of stereochemistry on lysophosphatidic acid mimetic activity, synthesis of optically pure stereoisomers of selected Darmstoff analogs was achieved starting with chiral methyl glycerates. Each Darmstoff analog was evaluated for subtype-specific LPA receptor agonist/antagonist activity, PPARgamma activation, and autotaxin inhibition. From this study we identified compound 12 as a pan-antagonist and several pan-agonists for the LPA(1-3) receptors. Introduction of an aromatic ring in the lipid chain such as analog 22 produced a subtype-specific LPA(3) agonist with an EC(50) of 692 nM. Interestingly, regardless of their LPA(1/2/3) ligand properties all of the Darmstoff analogs tested activated PPARgamma. However, these compounds are weak inhibitors of autotaxin. The results indicate that Darmstoff analogs constitute a novel class of lysophosphatidic acid mimetics.

  4. Mutations of lysophosphatidic acid receptor-1 gene during progression of lung tumors in rats

    SciTech Connect

    Yamada, Takanori; Obo, Yumi; Furukawa, Mami; Hotta, Mayuko; Yamasaki, Ayako; Honoki, Kanya; Fukushima, Nobuyuki; Tsujiuchi, Toshifumi

    2009-01-16

    Lysophosphatidic acid (LPA) is a bioactive phospholipid that stimulates cell proliferation, migration, and protects cells from apoptosis. It interacts with specific G protein-coupled transmembrane receptors. In this study, mutations of lysophosphatidic acid receptor-1 (LPA1) gene were investigated to clarify the possible molecular mechanisms underlying the development of lung tumors induced by N-nitrosobis(2-hydroxypropyl)amine (BHP) in rats. Male Wistar rats, 6 weeks of age, were given 2000 ppm BHP in their drinking water for 12 weeks and then maintained without further treatment until sacrifice at 25 weeks. Genomic DNAs were extracted from paraffin-embedded tissues and exons 2-4 were examined for mutations, using polymerase chain reaction (PCR)-single strand conformation polymorphism (SSCP) analysis. No LPA1 mutations were detected in 15 hyperplasias, but 2 out of 12 adenomas (16.7%) and 7 out of 17 adenocarcinomas (41.2%). These results suggest that mutations of LPA1 gene may be involved in the acquisition of growth advantage from adenomas to adenocarcinomas in lung carcinogenesis induced in rats by BHP.

  5. Orally administered phosphatidic acids and lysophosphatidic acids ameliorate aspirin-induced stomach mucosal injury in mice.

    PubMed

    Tanaka, Tamotsu; Morito, Katsuya; Kinoshita, Masafumi; Ohmoto, Mayumi; Urikura, Mai; Satouchi, Kiyoshi; Tokumura, Akira

    2013-04-01

    Recent investigations revealed that lysophosphatidic acid (LPA), a phospholipid with a growth factor-like activity, plays an important role in the integrity of the gastrointestinal tract epithelium. This paper attempts to clarify the effect of orally administered phosphatidic acid (PA) and LPA on aspirin-induced gastric lesions in mice. Phospholipids, a free fatty acid, a diacylglycerol and a triglyceride at 1 mM (5.7 μmol/kg body weight) or 0.1 mM were orally administered to mice 0.5 h before oral administration of aspirin (1.7 mmol/kg). The total length of lesions formed on the stomach wall was measured as a lesion index. Formation of LPA from PA in the mouse stomach was examined by in vitro (in stomach lavage fluid), ex vivo (in an isolated stomach) and in vivo (in the stomach of a living mouse) examinations of phospholipase activity. Palmitic acid, dioleoyl-glycerol, olive oil and lysophosphatidylcholine did not affect the aspirin-induced lesions. In contrast, phosphatidylcholine (1 mM), LPA (1 mM) and PA (0.1, 1 mM) significantly reduced the lesion index. Evidence for formation of LPA from PA in the stomach by gastric phospholipase A2 was obtained by in vitro, ex vivo and in vivo experiments. An LPA-specific receptor, LPA2, was found to be localized on the gastric surface-lining cells of mice. Pretreatment with PA-rich diets may prevent nonsteroidal anti-inflammatory drug-induced stomach ulcers.

  6. Pro-Lipogenic Action of Lysophosphatidic Acid in Ovarian Cancer

    DTIC Science & Technology

    2013-07-01

    One of the key mediators of fatty acid b-oxidation is carnitine pamitoyl transferase 1A (CPT1A), which is overexpressed in malignant ovarian...phospholipases is consistent with our previous observation that exogenously supplemented LPA did not fully reverse the effect of the iPLA2b inhibitor BEL on...MAGL, inhibits growth of ovarian cancer cell lines. Most interestingly, inhibition of carnitine palmitoyl transferase 1 (CPT1), the rate-limiting

  7. Lysophosphatidic acid inhibits adipocyte differentiation via lysophosphatidic acid 1 receptor-dependent down-regulation of peroxisome proliferator-activated receptor gamma2.

    PubMed

    Simon, Marie Françoise; Daviaud, Danièle; Pradère, Jean Philippe; Grès, Sandra; Guigné, Charlotte; Wabitsch, Martin; Chun, Jerold; Valet, Philippe; Saulnier-Blache, Jean Sébastien

    2005-04-15

    Lysophosphatidic acid (LPA) is a bioactive phospholipid acting via specific G protein-coupled receptors that is synthesized at the extracellular face of adipocytes by a secreted lysophospholipase D (autotaxin). Preadipocytes mainly express the LPA(1) receptor subtype, and LPA increases their proliferation. In monocytes and CV1 cells LPA was recently reported to bind and activate peroxisome proliferator-activated receptor gamma (PPARgamma), a transcription factor also known to play a pivotal role in adipogenesis. Here we show that, unlike the PPARgamma agonist rosiglitazone, LPA was unable to increase transcription of PPARgamma-sensitive genes (PEPCK and ALBP) in the mouse preadipose cell line 3T3F442A. In contrast, treatment with LPA decreased PPARgamma2 expression, impaired the response of PPARgamma-sensitive genes to rosiglitazone, reduced triglyceride accumulation, and reduced the expression of adipocyte mRNA markers. The anti-adipogenic activity of LPA was also observed in the human SGBS (Simpson-Golabi-Behmel syndrome) preadipocyte cell line, as well as in primary preadipocytes isolated from wild type mice. Conversely, the anti-adipogenic activity of LPA was not observed in primary preadipocytes from LPA(1) receptor knock-out mice, which, in parallel, exhibited a higher adiposity than wild type mice. In conclusion, LPA does not behave as a potent PPARgamma agonist in adipocytes but, conversely, inhibits PPARgamma expression and adipogenesis via LPA(1) receptor activation. The local production of LPA may exert a tonic inhibitory effect on the development of adipose tissue.

  8. Autotaxin-lysophosphatidic acid receptor signalling regulates hepatitis C virus replication.

    PubMed

    Farquhar, Michelle J; Humphreys, Isla S; Rudge, Simon A; Wilson, Garrick K; Bhattacharya, Bishnupriya; Ciaccia, Maria; Hu, Ke; Zhang, Qifeng; Mailly, Laurent; Reynolds, Gary M; Ashcroft, Margaret; Balfe, Peter; Baumert, Thomas F; Roessler, Stephanie; Wakelam, Michael J O; McKeating, Jane A

    2017-05-01

    Chronic hepatitis C is a global health problem with an estimated 170 million hepatitis C virus (HCV) infected individuals at risk of progressive liver disease and hepatocellular carcinoma (HCC). Autotaxin (ATX, gene name: ENPP2) is a phospholipase with diverse roles in the physiological and pathological processes including inflammation and oncogenesis. Clinical studies have reported increased ATX expression in chronic hepatitis C, however, the pathways regulating ATX and its role in the viral life cycle are not well understood. In vitro hepatocyte and ex vivo liver culture systems along with chimeric humanized liver mice and HCC tissue enabled us to assess the interplay between ATX and the HCV life cycle. HCV infection increased hepatocellular ATX RNA and protein expression. HCV infection stabilizes hypoxia inducible factors (HIFs) and we investigated a role for these transcription factors to regulate ATX. In vitro studies show that low oxygen increases hepatocellular ATX expression and transcriptome analysis showed a positive correlation between ATX mRNA levels and hypoxia gene score in HCC tumour tissue associated with HCV and other aetiologies. Importantly, inhibiting ATX-lysophosphatidic acid (LPA) signalling reduced HCV replication, demonstrating a positive role for this phospholipase in the viral life cycle. LPA activates phosphoinositide-3-kinase that stabilizes HIF-1α and inhibiting the HIF signalling pathway abrogates the pro-viral activity of LPA. Our data support a model where HCV infection increases ATX expression which supports viral replication and HCC progression. Chronic hepatitis C is a global health problem with infected individuals at risk of developing liver disease that can progress to hepatocellular carcinoma. Autotaxin generates the biologically active lipid lysophosphatidic acid that has been reported to play a tumorigenic role in a wide number of cancers. In this study we show that hepatitis C virus infection increases autotaxin expression

  9. Lysophosphatidic acid directly activates TRPV1 through a C-terminal binding site.

    PubMed

    Nieto-Posadas, Andrés; Picazo-Juárez, Giovanni; Llorente, Itzel; Jara-Oseguera, Andrés; Morales-Lázaro, Sara; Escalante-Alcalde, Diana; Islas, León D; Rosenbaum, Tamara

    2011-11-20

    Since 1992, there has been growing evidence that the bioactive phospholipid lysophosphatidic acid (LPA), whose amounts are increased upon tissue injury, activates primary nociceptors resulting in neuropathic pain. The TRPV1 ion channel is expressed in primary afferent nociceptors and is activated by physical and chemical stimuli. Here we show that in control mice LPA produces acute pain-like behaviors, which are substantially reduced in Trpv1-null animals. Our data also demonstrate that LPA activates TRPV1 through a unique mechanism that is independent of G protein-coupled receptors, contrary to what has been widely shown for other ion channels, by directly interacting with the C terminus of the channel. We conclude that TRPV1 is a direct molecular target of the pain-producing molecule LPA and that this constitutes, to our knowledge, the first example of LPA binding directly to an ion channel to acutely regulate its function.

  10. A chromo- and fluorogenic sensor for probing the cancer biomarker lysophosphatidic acid.

    PubMed

    Zhao, Wenwen; Liu, Weimin; Zhang, Wenjun; Zeng, Lintao; Fan, Zhiyuan; Wu, Jiasheng; Wang, Pengfei

    2012-04-21

    A novel chromo- and fluorogenic sensor, 4-(4-dimethylaminostyryl)-1-hexadecylpyridinium (DSHP) for lysophosphatidic acid (LPA) was successfully developed by incorporating a long alkyl chain into the cyanine molecule. DSHP shows excellent selectivity and high sensitivity towards LPA with a detection limit of about 7.09 × 10(-7) M based on electrostatic and hydrophobic interactions between the sensor and LPA. Upon addition of LPA ranging from 0 to 7.5 × 10(-4) M, DSHP displays an 'on-off-on' fluorescence response and obvious colour change. Good linear relationships between the fluorescence intensity and LPA concentrations were achieved in the fluorescence quenching ranges of 0-28 μM and 34-52 μM, which could be attributed to the combined effects of the photoinduced electron transfer and LPA-induced aggregation of the sensor molecules.

  11. Lysophosphatidic Acid Receptor Is a Functional Marker of Adult Hippocampal Precursor Cells.

    PubMed

    Walker, Tara L; Overall, Rupert W; Vogler, Steffen; Sykes, Alex M; Ruhwald, Susann; Lasse, Daniela; Ichwan, Muhammad; Fabel, Klaus; Kempermann, Gerd

    2016-04-12

    Here, we show that the lysophosphatidic acid receptor 1 (LPA1) is expressed by a defined population of type 1 stem cells and type 2a precursor cells in the adult mouse dentate gyrus. LPA1, in contrast to Nestin, also marks the quiescent stem cell population. Combining LPA1-GFP with EGFR and prominin-1 expression, we have enabled the prospective separation of both proliferative and non-proliferative precursor cell populations. Transcriptional profiling of the isolated proliferative precursor cells suggested immune mechanisms and cytokine signaling as molecular regulators of adult hippocampal precursor cell proliferation. In addition to LPA1 being a marker of this important stem cell population, we also show that the corresponding ligand LPA is directly involved in the regulation of adult hippocampal precursor cell proliferation and neurogenesis, an effect that can be attributed to LPA signaling via the AKT and MAPK pathways. Copyright © 2016 The Authors. Published by Elsevier Inc. All rights reserved.

  12. Phosphorothioate analogs of sn-2 radyl lysophosphatidic acid (LPA): metabolically stabilized LPA receptor agonists.

    PubMed

    Jiang, Guowei; Inoue, Asuka; Aoki, Junken; Prestwich, Glenn D

    2013-03-15

    We describe an efficient synthesis of metabolically stabilized sn-2 radyl phosphorothioate analogs of lysophosphatidic acid (LPA), and the determination of the agonist activity of each analog for the six LPA receptors (LPA1-6) using a recently developed TGFα shedding assay. In general, the sn-2 radyl OMPT analogs showed similar agonist activities to the previous 1-oleoyl-2-O-methyl-glycerophosphothioate (sn-1 OMPT) analogs for LPA1-6 receptors. In most cases, the sn-2 radyl-OMPT analogs were more potent agonists than LPA itself. Most importantly, sn-2 alkyl OMPT analogs were very potent LPA5 and LPA6 agonists. The availability of sn-2 radyl OPMT analogs further refines the structure-activity relationships for ligand-receptor interactions for this class of GPCRs. Copyright © 2013 Elsevier Ltd. All rights reserved.

  13. Inhibitory effects of lysophosphatidic acid receptor-5 on cellular functions of sarcoma cells.

    PubMed

    Araki, Mutsumi; Kitayoshi, Misaho; Dong, Yan; Hirane, Miku; Ozaki, Shuhei; Mori, Shiori; Fukushima, Nobuyuki; Honoki, Kanya; Tsujiuchi, Toshifumi

    2014-06-01

    Lysophosphatidic acid (LPA) is a bioactive lipid that interacts with G protein-coupled LPA receptors (LPA receptor-1 (LPA1) to LPA6). Here, we investigated the effects of LPA signaling via LPA5 on cellular functions of sarcoma cells by generating Lpar5 overexpressing and Lpar5 knockdown cells from rat osteosarcoma and malignant fibrous histiocytoma cells, respectively. The cell motility activity of Lpar5 overexpressing cells was significantly lower, while Lpar5 knockdown cells showed high cell motility, compared with respective controls. Gelatin zymography showed that LPA5 suppressed the activation of matrix metalloproteinase-2. LPA5 also inhibited the cell motility activity of endothelial cells, correlating with the expression levels of vascular endothelial growth factor genes. These results suggest that LPA signaling via LPA5 negatively regulates the cellular functions of rat sarcoma cells.

  14. The autotaxin-lysophosphatidic acid pathway in pathogenesis of rheumatoid arthritis.

    PubMed

    Orosa, Beatriz; García, Samuel; Conde, Carmen

    2015-10-15

    Lysophosphatidic acid (LPA) is a phospholipid that is mainly produced by the hydrolysis of lysophosphatidylcholine (LPC) by lysophospholipase D, which is also called autotaxin (ATX). LPA interacts with specific G-protein coupled receptors and is involved in the regulation of cellular survival, proliferation, differentiation and motility. LPA also has roles in several pathological disorders, such as cancer and pulmonary, dermal and renal fibrosis. The involvement of the ATX-LPA pathway has recently been demonstrated in inflammatory responses and apoptosis of fibroblast-like synoviocytes (FLS) from patients with rheumatoid arthritis and during the development of experimental arthritis. This review summarises the current literature of the ATX-LPA pathway in rheumatoid arthritis. Copyright © 2015 Elsevier B.V. All rights reserved.

  15. Steroid binding to Autotaxin links bile salts and lysophosphatidic acid signalling.

    PubMed

    Keune, Willem-Jan; Hausmann, Jens; Bolier, Ruth; Tolenaars, Dagmar; Kremer, Andreas; Heidebrecht, Tatjana; Joosten, Robbie P; Sunkara, Manjula; Morris, Andrew J; Matas-Rico, Elisa; Moolenaar, Wouter H; Oude Elferink, Ronald P; Perrakis, Anastassis

    2016-04-14

    Autotaxin (ATX) generates the lipid mediator lysophosphatidic acid (LPA). ATX-LPA signalling is involved in multiple biological and pathophysiological processes, including vasculogenesis, fibrosis, cholestatic pruritus and tumour progression. ATX has a tripartite active site, combining a hydrophilic groove, a hydrophobic lipid-binding pocket and a tunnel of unclear function. We present crystal structures of rat ATX bound to 7α-hydroxycholesterol and the bile salt tauroursodeoxycholate (TUDCA), showing how the tunnel selectively binds steroids. A structure of ATX simultaneously harbouring TUDCA in the tunnel and LPA in the pocket, together with kinetic analysis, reveals that bile salts act as partial non-competitive inhibitors of ATX, thereby attenuating LPA receptor activation. This unexpected interplay between ATX-LPA signalling and select steroids, notably natural bile salts, provides a molecular basis for the emerging association of ATX with disorders associated with increased circulating levels of bile salts. Furthermore, our findings suggest potential clinical implications in the use of steroid drugs.

  16. Synthesis of Photoactivatable Analogues of Lysophosphatidic Acid and Covalent Labeling of Plasma Proteins

    PubMed Central

    Li, Zaiguo; Baker, Daniel L.; Tigyi, Gabor; Bittman, Robert

    2008-01-01

    Lysophosphatidic acid bearing a benzophenone group in either the sn-1 or sn-2 chain of an oleoyl-type ester or oleyl-type ether chain and 32P in the phosphate group were synthesized. The benzophenone moiety was introduced by selective hydroboration of the double bond of enyne 11 at low temperature, followed by Suzuki reaction with 4-bromobenzophenone. The key intermediates for the preparation of ester-linked LPA 1 and 3 were obtained in one pot by a modified DIBAL-H reduction of orthoformate intermediate 22. These probes were shown to covalently modify a single protein target in rat plasma containing albumin and several protein targets in rat plasma containing a low level of albumin. PMID:16408973

  17. Molecular basis of lysophosphatidic acid-induced NF-κB activation.

    PubMed

    Sun, Wenjing; Yang, Jianhua

    2010-12-01

    PKC, β-arrestin 2, CARMA3, BCL10, MALT1, TRAF6 and MEKK3 are signaling proteins that have a key role in G protein-coupled receptor (GPCR)-mediated activation of nuclear factor-κB (NF-κB) pathway in nonhematopoietic cells in response to lysophosphatidic acid (LPA) stimulation. The PKC, β-arrestin 2, CARMA3-BCL10-MALT1-TRAF6 signalosome, and MEKK3 functions as a link between GPCR signaling and IKK-NF-κB activation. Here we briefly summarize recent progress in the understanding of the molecular and biological functions of these proteins in GPCR-mediated NF-κB activation in nonhematopoietic cells. Copyright © 2010 Elsevier Inc. All rights reserved.

  18. Autotaxin, a lysophosphatidic acid-producing ectoenzyme, promotes lymphocyte entry into secondary lymphoid organs

    PubMed Central

    Kanda, Hidenobu; Newton, Rebecca; Klein, Russell; Morita, Yuka; Gunn, Michael D.; Rosen, Steven D.

    2009-01-01

    The extracellular lysophospholipase D, autotaxin (ATX), and its product lysophosphatidic acid (LPA) have diverse roles in development and cancer, but little is known about functions in the immune system. We found that ATX was highly expressed in high endothelial venules (HEVs) of lymphoid organs and was secreted. Chemokine-activated lymphocytes expressed enhanced receptors for ATX, providing a mechanism to target the secreted ATX onto lymphocytes undergoing recruitment. LPA induced chemokinesis in T-cells. Intravenous injection of enzymatically inactive ATX attenuated homing of T-cells to lymphoid tissues, likely by competing with endogenous ATX and exerting a dominant-negative effect. Our results support a novel and general step in the homing cascade, in which the ectoenzyme ATX facilitates lymphocyte entry into lymphoid organs. PMID:18327261

  19. Lysophosphatidic acid induces vasodilation mediated by LPA1 receptors, phospholipase C, and endothelial nitric oxide synthase

    PubMed Central

    Ruisanchez, Éva; Dancs, Péter; Kerék, Margit; Németh, Tamás; Faragó, Bernadett; Balogh, Andrea; Patil, Renukadevi; Jennings, Brett L.; Liliom, Károly; Malik, Kafait U.; Smrcka, Alan V.; Tigyi, Gabor; Benyó, Zoltán

    2014-01-01

    Lysophosphatidic acid (LPA) has been implicated as a mediator of several cardiovascular functions, but its potential involvement in the control of vascular tone is obscure. Here, we show that both LPA (18:1) and VPC31143 (a synthetic agonist of LPA1–3 receptors) relax intact mouse thoracic aorta with similar Emax values (53.9 and 51.9% of phenylephrine-induced precontraction), although the EC50 of LPA- and VPC31143-induced vasorelaxations were different (400 vs. 15 nM, respectively). Mechanical removal of the endothelium or genetic deletion of endothelial nitric oxide synthase (eNOS) not only diminished vasorelaxation by LPA or VPC31143 but converted it to vasoconstriction. Freshly isolated mouse aortic endothelial cells expressed LPA1, LPA2, LPA4 and LPA5 transcripts. The LPA1,3 antagonist Ki16425, the LPA1 antagonist AM095, and the genetic deletion of LPA1, but not that of LPA2, abolished LPA-induced vasorelaxation. Inhibition of the phosphoinositide 3 kinase–protein kinase B/Akt pathway by wortmannin or MK-2206 failed to influence the effect of LPA. However, pharmacological inhibition of phospholipase C (PLC) by U73122 or edelfosine, but not genetic deletion of PLCε, abolished LPA-induced vasorelaxation and indicated that a PLC enzyme, other than PLCε, mediates the response. In summary, the present study identifies LPA as an endothelium-dependent vasodilator substance acting via LPA1, PLC, and eNOS.—Ruisanchez, É., Dancs, P., Kerék, M., Németh, T., Faragó, B., Balogh, A., Patil, R., Jennings, B. L., Liliom, K., Malik, K. U., Smrcka, A. V., Tigyi, G., Benyó, Z. Lysophosphatidic acid induces vasodilation mediated by LPA1 receptors, phospholipase C, and endothelial nitric oxide synthase. PMID:24249637

  20. Cloning, Characterization, and Expression Analysis of a Gene Encoding a Putative Lysophosphatidic Acid Acyltransferase from Seeds of Paeonia rockii.

    PubMed

    Zhang, Qing-Yu; Niu, Li-Xin; Yu, Rui; Zhang, Xiao-Xiao; Bai, Zhang-Zhen; Duan, Ke; Gao, Qing-Hua; Zhang, Yan-Long

    2017-06-01

    Tree peony (Paeonia section Moutan DC.) is an excellent woody oil crop, and the cloning and functional analysis of genes related to fatty acid (FA) metabolism from this organism has not been reported. Lysophosphatidic acid acyltransferase (LPAAT), which converts lysophosphatidic acid (LPA) to phosphatidic acid (PA), catalyzes the addition of fatty acyl moieties to the sn-2 position of the LPA glycerol backbone in triacylglycerol (TAG) biosynthesis. This project reports a putative lysophosphatidic acid acyltransferase gene PrLPAAT1 isolated from Paeonia rockii. Our data indicated that PrLPAAT1 has 1047 nucleotides and encodes a putative 38.8 kDa protein with 348 amino acid residues. Bioinformatic analysis demonstrated that PrLPAAT1 contains two transmembrane domains (TMDs). Subcellular localization analysis confirmed that PrLPAAT1 is a plasma membrane protein. Phylogenetic analysis revealed that PrLPAAT1 shared 74.3 and 65.5% amino acid sequence identities with the LPAAT1 sequences from columbine and grape, respectively. PrLPAAT1 belongs to AGPAT family, and may have acyltransferase activity. PrLPAAT1 was ubiquitously expressed in diverse tissues, and PrLPAAT1 expression was higher in the flower and developing seed. PrLPAAT1 is probably an important component in the FA accumulation process, especially during the early stages of seed development. PrLPAAT1 overexpression using a seed-specific promoter increased total FA content and the main FA accumulation in Arabidopsis transgenic plants.

  1. Rho/ROCK acts downstream of lysophosphatidic acid receptor 1 in modulating P2X3 receptor-mediated bone cancer pain in rats.

    PubMed

    Wu, Jing-Xiang; Yuan, Xiao-Min; Wang, Qiong; Wei, Wang; Xu, Mei-Ying

    2016-01-01

    Lysophosphatidic acid receptor 1 and Rho/ROCK signaling is implicated in bone cancer pain development. However, it remains unknown whether the two signaling pathways function together in P2X3 receptor-mediated bone cancer pain. In this study, using a rat model of bone cancer, we examined the expression of P2X3 and lysophosphatidic acid receptor 1 in rat dorsal root ganglion neurons and further dissected whether lysophosphatidic acid receptor 1 and Rho/ROCK-mediated pathways interacted in modulating rat pain behavior. Bone cancer was established by inoculating Walker 256 cells into the left tibia of female Wistar rats. We observed a gradual and yet significant decline in mean paw withdrawal threshold in rats with bone cancer, but not in control rats. Our immunohistochemical staining revealed that the number of P2X3- and lysophosphatidic acid receptor 1-positive dorsal root ganglion neurons was significantly greater in rats with bone cancer than control rats. Lysophosphatidic acid receptor 1 blockade with VPC32183 significantly attenuated decline in mean paw withdrawal threshold. Flinching behavior test further showed that lysophosphatidic acid receptor 1 inhibition with VPC32183 transiently but significantly attenuated α,β-meATP-induced increase in paw lift time per minute. Rho inhibition by intrathecal BoTXC3 caused a rapid reversal in decline in mean paw withdrawal threshold of rats with bone cancer. Flinching behavior test showed that BoTXC3 transiently and significantly attenuated α,β-meATP-induced increase in paw lift time per minute. Similar findings were observed with ROCK inhibition by intrathecal Y27632. Furthermore, VPC32183 and BoTXC3 effectively aborted the appearance of lysophosphatidic acid-induced calcium influx peak. Lysophosphatidic acid and its receptor LPAR1, acting through the Rho-ROCK pathway, regulate P2X3 receptor in the development of both mechanical and spontaneous pain in bone cancer. © The Author(s) 2016.

  2. Rho/ROCK acts downstream of lysophosphatidic acid receptor 1 in modulating P2X3 receptor-mediated bone cancer pain in rats

    PubMed Central

    Wu, Jing-xiang; Yuan, Xiao-min; Wang, Qiong; Wei, Wang

    2016-01-01

    Background Lysophosphatidic acid receptor 1 and Rho/ROCK signaling is implicated in bone cancer pain development. However, it remains unknown whether the two signaling pathways function together in P2X3 receptor-mediated bone cancer pain. Results In this study, using a rat model of bone cancer, we examined the expression of P2X3 and lysophosphatidic acid receptor 1 in rat dorsal root ganglion neurons and further dissected whether lysophosphatidic acid receptor 1 and Rho/ROCK-mediated pathways interacted in modulating rat pain behavior. Bone cancer was established by inoculating Walker 256 cells into the left tibia of female Wistar rats. We observed a gradual and yet significant decline in mean paw withdrawal threshold in rats with bone cancer, but not in control rats. Our immunohistochemical staining revealed that the number of P2X3- and lysophosphatidic acid receptor 1-positive dorsal root ganglion neurons was significantly greater in rats with bone cancer than control rats. Lysophosphatidic acid receptor 1 blockade with VPC32183 significantly attenuated decline in mean paw withdrawal threshold. Flinching behavior test further showed that lysophosphatidic acid receptor 1 inhibition with VPC32183 transiently but significantly attenuated α,β-meATP-induced increase in paw lift time per minute. Rho inhibition by intrathecal BoTXC3 caused a rapid reversal in decline in mean paw withdrawal threshold of rats with bone cancer. Flinching behavior test showed that BoTXC3 transiently and significantly attenuated α,β-meATP-induced increase in paw lift time per minute. Similar findings were observed with ROCK inhibition by intrathecal Y27632. Furthermore, VPC32183 and BoTXC3 effectively aborted the appearance of lysophosphatidic acid-induced calcium influx peak. Conclusions Lysophosphatidic acid and its receptor LPAR1, acting through the Rho-ROCK pathway, regulate P2X3 receptor in the development of both mechanical and spontaneous pain in bone cancer. PMID:27094551

  3. Measurement of Lysophosphatidic Acid and Sphingosine-1-Phosphate by Liquid Chromatography-Coupled Electrospray Ionization Tandem Mass Spectrometry.

    PubMed

    Kraemer, Maria P; Halder, Suchismita; Smyth, Susan S; Morris, Andrew J

    2017-08-03

    Lysophosphatidic acids and sphingosine-1-phosphate are bioactive lipids that regulate diverse cellular and physiological processes through actions that are largely mediated by cell surface receptors. The roles played by these lipids in multiple disease processes make the enzymes and receptors involved in their synthesis, inactivation, and signaling attractive targets for pharmacological therapies. In this chapter we describe methods for sensitive accurate quantitation of LPA and S1P levels in biological fluids using liquid chromatography-coupled electrospray ionization tandem mass spectrometry.

  4. The gep proto-oncogene Gα13 mediates lysophosphatidic acid-mediated migration of pancreatic cancer cells.

    PubMed

    Gardner, Jacob A; Ha, Ji Hee; Jayaraman, Muralidharan; Dhanasekaran, Danny N

    2013-07-01

    Tumor microenvironment, defined by a variety of growth factors including lysophosphatidic acid (LPA), whose levels are increased in pancreatic cancer patients, plays a major role in the genesis and progression of pancreatic cancer. Because the gep proto-oncogenes, Gα12 and Gα13, are implicated in LPA-stimulated oncogenic signaling, this study is focused on evaluating the role of these proto-oncogenes in LPA-stimulated invasive migration of pancreatic cancer cells. Effect of LPA on the migration and proliferation of pancreatic cancer cells was assessed using BxPC3, Dan-G, MDAPanc-28, Panc-1, and PaCa-2 cell lines. The role of Gα13 in the migration of pancreatic cancer cells was interrogated by disrupting lysophosphatidic acid receptor-Gα13 interaction using CT13, a dominant negative mutant of Gα13, and by silencing the expression of Gα13. Results indicate that LPA stimulates the migration of pancreatic cancer cells and such LPA-stimulated migratory response is mediated by Gα13. Furthermore, the results establish that the silencing of Gα13, but not Gα12, abrogates LPA-stimulated invasive migration of pancreatic cancer cells. These results report for the first time a critical role for Gα13 in LPA-stimulated invasive migration of pancreatic cancer cells. These findings identify LPA-lysophosphatidic acid receptor-Gα13 signaling node as a novel therapeutic target for pancreatic cancer treatment and control.

  5. Cyclic phosphatidic acid and lysophosphatidic acid induce hyaluronic acid synthesis via CREB transcription factor regulation in human skin fibroblasts.

    PubMed

    Maeda-Sano, Katsura; Gotoh, Mari; Morohoshi, Toshiro; Someya, Takao; Murofushi, Hiromu; Murakami-Murofushi, Kimiko

    2014-09-01

    Cyclic phosphatidic acid (cPA) is a naturally occurring phospholipid mediator and an analog of the growth factor-like phospholipid lysophosphatidic acid (LPA). cPA has a unique cyclic phosphate ring at the sn-2 and sn-3 positions of its glycerol backbone. We showed before that a metabolically stabilized cPA derivative, 2-carba-cPA, relieved osteoarthritis pathogenesis in vivo and induced hyaluronic acid synthesis in human osteoarthritis synoviocytes in vitro. This study focused on hyaluronic acid synthesis in human fibroblasts, which retain moisture and maintain health in the dermis. We investigated the effects of cPA and LPA on hyaluronic acid synthesis in human fibroblasts (NB1RGB cells). Using particle exclusion and enzyme-linked immunosorbent assays, we found that both cPA and LPA dose-dependently induced hyaluronic acid synthesis. We revealed that the expression of hyaluronan synthase 2 messenger RNA and protein is up-regulated by cPA and LPA treatment time dependently. We then characterized the signaling pathways up-regulating hyaluronic acid synthesis mediated by cPA and LPA in NB1RGB cells. Pharmacological inhibition and reporter gene assays revealed that the activation of the LPA receptor LPAR1, Gi/o protein, phosphatidylinositol-3 kinase (PI3K), extracellular-signal-regulated kinase (ERK), and cyclic adenosine monophosphate response element-binding protein (CREB) but not nuclear factor κB induced hyaluronic acid synthesis by the treatment with cPA and LPA in NB1RGB cells. These results demonstrate for the first time that cPA and LPA induce hyaluronic acid synthesis in human skin fibroblasts mainly through the activation of LPAR1-Gi/o followed by the PI3K, ERK, and CREB signaling pathway. Copyright © 2014 The Authors. Published by Elsevier B.V. All rights reserved.

  6. A novel highly potent autotaxin/ENPP2 inhibitor produces prolonged decreases in plasma lysophosphatidic acid formation in vivo and regulates urethral tension.

    PubMed

    Saga, Hiroshi; Ohhata, Akira; Hayashi, Akio; Katoh, Makoto; Maeda, Tatsuo; Mizuno, Hirotaka; Takada, Yuka; Komichi, Yuka; Ota, Hiroto; Matsumura, Naoya; Shibaya, Masami; Sugiyama, Tetsuya; Nakade, Shinji; Kishikawa, Katsuya

    2014-01-01

    Autotaxin, also known as ectonucleotide pyrophosphatase/phosphodiesterase 2 (ENPP2), is a secreted enzyme that has lysophospholipase D activity, which converts lysophosphatidylcholine to bioactive lysophosphatidic acid. Lysophosphatidic acid activates at least six G-protein coupled recpetors, which promote cell proliferation, survival, migration and muscle contraction. These physiological effects become dysfunctional in the pathology of cancer, fibrosis, and pain. To date, several autotaxin/ENPP2 inhibitors have been reported; however, none were able to completely and continuously inhibit autotaxin/ENPP2 in vivo. In this study, we report the discovery of a highly potent autotaxin/ENPP2 inhibitor, ONO-8430506, which decreased plasma lysophosphatidic acid formation. The IC50 values of ONO-8540506 for lysophospholipase D activity were 6.4-19 nM for recombinant autotaxin/ENPP2 proteins and 4.7-11.6 nM for plasma from various animal species. Plasma lysophosphatidic acid formation during 1-h incubation was almost completely inhibited by the addition of >300 nM of the compound to human plasma. In addition, when administered orally to rats at a dose of 30 mg/kg, the compound demonstrated good pharmacokinetics in rats and persistently inhibited plasma lysophosphatidic acid formation even at 24 h after administration. Smooth muscle contraction is a known to be promoted by lysophosphatidic acid. In this study, we showed that dosing rats with ONO-8430506 decreased intraurethral pressure accompanied by urethral relaxation. These findings demonstrate the potential of this autotaxin/ENPP2 inhibitor for the treatment of various diseases caused by lysophosphatidic acid, including urethral obstructive disease such as benign prostatic hyperplasia.

  7. Toluene diisocyanate: Induction of the autotaxin-lysophosphatidic acid axis and its association with airways symptoms

    SciTech Connect

    Broström, Julia M.; Ye, Zhi-wei; Axmon, Anna; Littorin, Margareta; Tinnerberg, Håkan; Lindh, Christian H.; Zheng, Huiyuan; Ghalali, Aram; Stenius, Ulla; Jönsson, Bo A.G.; Högberg, Johan

    2015-09-15

    Diisocyanates are industrial chemicals which have a wide range of applications in developed and developing countries. They are notorious lung toxicants and respiratory sensitizers. However, the mechanisms behind their adverse effects are not adequately characterized. Autotaxin (ATX) is an enzyme producing lysophosphatidic acid (LPA), and the ATX-LPA axis has been implicated in lung related inflammatory conditions and diseases, including allergic asthma, but not to toxicity of environmental low-molecular-weight chemicals. We investigated effects of toluene diisocyanate (TDI) on ATX induction in human lung epithelial cell models, and we correlated LPA-levels in plasma to biomarkers of TDI exposure in urine collected from workers exposed to < 5 ppb (parts per billion). Information on workers' symptoms was collected through interviews. One nanomolar TDI robustly induced ATX release within 10 min in vitro. A P2X7- and P2X4-dependent microvesicle formation was implicated in a rapid ATX release and a subsequent protein synthesis. Co-localization between purinergic receptors and ATX was documented by immunofluorescence and confocal microscopy. The release was modulated by monocyte chemoattractant protein-1 (MCP-1) and by extracellular ATP. In workers, we found a dose–response relationship between TDI exposure biomarkers in urine and LPA levels in plasma. Among symptomatic workers reporting “sneezing”, the LPA levels were higher than among non-symptomatic workers. This is the first report indicating induction of the ATX-LPA axis by an environmental low-molecular-weight chemical, and our data suggest a role for the ATX-LPA axis in TDI toxicity. - Highlights: • Human epithelial cells release autotaxin in response to 1 nM toluene diisocyanate (TDI). • The release involves P2X4 and P2X7 receptors and is modulated by ATP and MCP-1. • Lysophosphatidic acid (LPA) was measured in workers exposed to < 5 ppb TDI. • LPA in plasma correlated to TDI exposure biomarkers in

  8. Blockade of lysophosphatidic acid receptors LPAR1/3 ameliorates lung fibrosis induced by irradiation

    SciTech Connect

    Gan, Lu; Xue, Jian-Xin; Li, Xin; Liu, De-Song; Ge, Yan; Ni, Pei-Yan; Deng, Lin; Lu, You; Jiang, Wei

    2011-05-27

    Highlights: {yields} Lysophosphatidic acid (LPA) levels and its receptors LPAR1/3 transcripts were elevated during the development of radiation-induced lung fibrosis. {yields} Lung fibrosis was obviously alleviated in mice treated with the dual LPAR1/3 antagonist, VPC12249. {yields} VPC12249 administration effectively inhibited radiation-induced fibroblast accumulation in vivo, and suppressed LPA-induced fibroblast proliferation in vitro. {yields} LPA-LPAR1/3 signaling regulated TGF{beta}1 and CTGF expressions in radiation-challenged lungs, but only influenced CTGF expression in cultured fibroblasts. {yields} LPA-LPAR1/3 signaling induced fibroblast proliferation through a CTGF-dependent pathway, rather than through TGF{beta}1 activation. -- Abstract: Lung fibrosis is a common and serious complication of radiation therapy for lung cancer, for which there are no efficient treatments. Emerging evidence indicates that lysophosphatidic acid (LPA) and its receptors (LPARs) are involved in the pathogenesis of fibrosis. Here, we reported that thoracic radiation with 16 Gy in mice induced development of radiation lung fibrosis (RLF) accompanied by obvious increases in LPA release and LPAR1 and LPAR3 (LPAR1/3) transcripts. RLF was significantly alleviated in mice treated with the dual LPAR1/3 antagonist, VPC12249. VPC12249 administration effectively prolonged animal survival, restored lung structure, inhibited fibroblast accumulation and reduced collagen deposition. Moreover, profibrotic cytokines in radiation-challenged lungs obviously decreased following administration of VPC12249, including transforming growth factor {beta}1 (TGF{beta}1) and connective tissue growth factor (CTGF). In vitro, LPA induced both fibroblast proliferation and CTGF expression in a dose-dependent manner, and both were suppressed by blockade of LPAR1/3. The pro-proliferative activity of LPA on fibroblasts was inhibited by siRNA directed against CTGF. Together, our data suggest that the LPA-LPAR1

  9. LPA(3), a unique G protein-coupled receptor for lysophosphatidic acid.

    PubMed

    Hama, Kotaro; Aoki, Junken

    2010-10-01

    Lysophosphatidic acid (LPA; 1- or 2-acyl-sn-glycerol-3-phosphate) is a phospholipid that is involved in numerous normal physiological and pathological processes such as brain development, blood vessel formation, embryo implantation, hair growth, neuropathic pain, lung fibrosis and colon cancer. Most of these functions are mediated by G protein-coupled receptors (GPCRs) specific to LPA. So far, six GPCRs for LPA have been identified: LPA(1)/Edg2, LPA(2)/Edg4, LPA(3)/Edg7, LPA(4)/GPR23/P2Y9, LPA(5)/GPR92 and LPA(6)/P2Y5. An intracellular target of LPA has also been proposed. Among the LPA receptors, LPA(3) is unique in that it is activated significantly by a specific form of LPA (2-acyl LPA with unsaturated fatty acids) and is expressed in a limited number of tissues such as the reproductive organs. Recent studies have shown that LPA(3)-mediated LPA signaling is essential for proper embryo implantation and have revealed an unexpected genetic linkage between LPA and prostaglandin signaling. Here we review recent advances in the study of LPA(3), especially studies using LPA(3)-deficient mice. In addition, we focus on the agonists and antagonists that are specific to each LPA receptor as important tools for the functional study of LPA signaling. Copyright © 2010 Elsevier Ltd. All rights reserved.

  10. Novel Inhibitory Effect of a Lysophosphatidic Acid 2 Agonist on Allergen-Driven Airway Inflammation.

    PubMed

    Knowlden, Sara A; Hillman, Sara E; Chapman, Timothy J; Patil, Renukadevi; Miller, Duane D; Tigyi, Gabor; Georas, Steve N

    2016-03-01

    Lysophosphatidic acid (LPA) is a pleiotropic lipid signaling molecule associated with asthma pathobiology. LPA elicits its effects by binding to at least six known cell surface G protein-coupled receptors (LPA1-6) that are expressed in the lung in a cell type-specific manner. LPA2 in particular has emerged as an attractive therapeutic target in asthma because it appears to transduce inhibitory or cell-protective signals. We studied a novel and specific small molecule LPA2 agonist (2-[4-(1,3-dioxo-1H,3H-benzoisoquinolin-2-yl)butylsulfamoyl] benzoic acid [DBIBB]) in a mouse model of house dust mite-induced allergic airway inflammation. Mice injected with DBIBB developed significantly less airway and lung inflammation compared with vehicle-treated controls. Levels of lung Th2 cytokines were also significantly attenuated by DBIBB. We conclude that pharmacologic activation of LPA2 attenuates Th2-driven allergic airway inflammation in a mouse model of asthma. Targeting LPA receptor signaling holds therapeutic promise in allergic asthma.

  11. Novel Inhibitory Effect of a Lysophosphatidic Acid 2 Agonist on Allergen-Driven Airway Inflammation

    PubMed Central

    Knowlden, Sara A.; Hillman, Sara E.; Chapman, Timothy J.; Patil, Renukadevi; Miller, Duane D.; Tigyi, Gabor

    2016-01-01

    Lysophosphatidic acid (LPA) is a pleiotropic lipid signaling molecule associated with asthma pathobiology. LPA elicits its effects by binding to at least six known cell surface G protein–coupled receptors (LPA1–6) that are expressed in the lung in a cell type–specific manner. LPA2 in particular has emerged as an attractive therapeutic target in asthma because it appears to transduce inhibitory or cell-protective signals. We studied a novel and specific small molecule LPA2 agonist (2-[4-(1,3-dioxo-1H,3H-benzoisoquinolin-2-yl)butylsulfamoyl] benzoic acid [DBIBB]) in a mouse model of house dust mite–induced allergic airway inflammation. Mice injected with DBIBB developed significantly less airway and lung inflammation compared with vehicle-treated controls. Levels of lung Th2 cytokines were also significantly attenuated by DBIBB. We conclude that pharmacologic activation of LPA2 attenuates Th2-driven allergic airway inflammation in a mouse model of asthma. Targeting LPA receptor signaling holds therapeutic promise in allergic asthma. PMID:26248018

  12. Biochemical and structural characterization of lysophosphatidic acid binding by a humanized monoclonal antibody

    PubMed Central

    Fleming, Jonathan K.; Wojciak, Jonathan M.; Campbell, Mary-Ann; Huxford, Tom

    2011-01-01

    Lysophosphatidic acid (LPA) is a common product of glycerophospholipid metabolism and an important mediator of signal transduction. Aberrantly high LPA concentrations accompany multiple disease states. One potential approach for treatment of these diseases, therefore, is the therapeutic application of antibodies that recognize and bind LPA as their antigen. We have determined the x-ray crystal structure of an anti-LPA antibody (LT3015) Fab fragment in its antigen-free form to 2.15 Å resolution and in complex with two LPA isotypes (14:0 and 18:2) to resolutions of 1.98 and 2.51 Å, respectively. The variable complementarity determining region (CDR) loops at the antigen binding site adopt nearly identical conformations in the free and antigen-bound crystal structures. The crystallographic models reveal that the LT3015 antibody employs both heavy and light chain CDR loops to create a network of eight hydrogen bonds with the glycerophosphate head group of its LPA antigen. The head group is almost completely excluded from contact with solvent, while the hydrocarbon tail is partially solvent exposed. In general, mutation of amino acid residues at the antigen binding site disrupts LPA binding. However, the introduction of particular mutations chosen strategically based upon the structures can positively influence LPA binding affinity. Finally, these structures elucidate the exquisite specificity demonstrated by an anti-lipid antibody for binding a structurally simple and seemingly unconstrained target molecule. PMID:21392506

  13. Lysophosphatidic Acid Induces Neurite Retraction in Differentiated Neuroblastoma Cells via GSK-3β Activation

    PubMed Central

    Sun, Yuanjie; Kim, Nam-Ho; Yang, Haijie; Kim, Seung-Hyuk; Huh, Sung-Oh

    2011-01-01

    Lysophosphatidic acid (LPA) is a lipid growth factor that exerts diverse biological effects, including rapid neurite retraction and cell migration. Alterations in cell morphology, including neurite retraction, in neurodegenerative disorders such as Alzheimer’s disease involve hyperphosphorylation of the cytoskeletal protein tau. Since LPA has been shown to induce neurite retraction in various cultured neural cells and the detailed underlying molecular mechanisms have not yet been elucidated, we investigated whether LPA induced neurite retraction through taumediated signaling pathways in differentiated neuroblastoma cells. When Neuro2a cells differentiated with retinoic acid (RA) were exposed to LPA, cells exhibited neurite retraction in a time-dependent manner. The retraction of neurites was accompanied by the phosphorylation of tau. The LPA-induced neurite retraction and tau phosphorylation in differentiated Neuro2a cells were significantly abolished by the glycogen synthase kinase-3β (GSK-3β) inhibitor lithium chloride. Interestingly, the LPA-stimulated tau phosphorylation and neurite retraction were markedly prevented by the administration of H89, an inhibitor of both cyclic-AMP dependent protein kinase (PKA) and cyclic- AMP response element-binding protein (CREB). Transfection of the dominant-negative CREBs, K-CREB and ACREB, failed to prevent LPA-induced tau phosphorylation and neurite retraction in differentiated Neuro2a cells. Taken together, these results suggest that GSK-3β and PKA, rather than CREB, play important roles in tau phosphorylation and neurite retraction in LPA-stimulated differentiated Neuro2a cells. PMID:21499833

  14. Biochemical and Structural Characterization of Lysophosphatidic Acid Binding by a Humanized Monoclonal Antibody

    SciTech Connect

    J Fleming; J Wojciak; M Campbell; T Huxford

    2011-12-31

    Lysophosphatidic acid (LPA) is a common product of glycerophospholipid metabolism and an important mediator of signal transduction. Aberrantly high LPA concentrations accompany multiple disease states. One potential approach for treatment of these diseases, therefore, is the therapeutic application of antibodies that recognize and bind LPA as their antigen. We have determined the X-ray crystal structure of an anti-LPA antibody (LT3015) Fab fragment in its antigen-free form to 2.15 {angstrom} resolution and in complex with two LPA isotypes (14:0 and 18:2) to resolutions of 1.98 and 2.51 {angstrom}, respectively. The variable CDR (complementarity-determining region) loops at the antigen binding site adopt nearly identical conformations in the free and antigen-bound crystal structures. The crystallographic models reveal that the LT3015 antibody employs both heavy- and light-chain CDR loops to create a network of eight hydrogen bonds with the glycerophosphate head group of its LPA antigen. The head group is almost completely excluded from contact with solvent, while the hydrocarbon tail is partially solvent-exposed. In general, mutation of amino acid residues at the antigen binding site disrupts LPA binding. However, the introduction of particular mutations chosen strategically on the basis of the structures can positively influence LPA binding affinity. Finally, these structures elucidate the exquisite specificity demonstrated by an anti-lipid antibody for binding a structurally simple and seemingly unconstrained target molecule.

  15. The autotaxin-lysophosphatidic acid-lysophosphatidic acid receptor cascade: proposal of a novel potential therapeutic target for treating glioblastoma multiforme.

    PubMed

    Tabuchi, Sadaharu

    2015-06-18

    Glioblastoma multiforme (GBM) is the most malignant tumor of the central nervous system (CNS). Its prognosis is one of the worst among all cancer types, and it is considered a fatal malignancy, incurable with conventional therapeutic strategies. As the bioactive multifunctional lipid mediator lysophosphatidic acid (LPA) is well recognized to be involved in the tumorigenesis of cancers by acting on G-protein-coupled receptors, LPA receptor (LPAR) antagonists and LPA synthesis inhibitors have been proposed as promising drugs for cancer treatment. Six LPARs, named LPA1-6, are currently recognized. Among them, LPA1 is the dominant LPAR in the CNS and is highly expressed in GBM in combination with the overexpression of autotaxin (ATX), the enzyme (a phosphodiesterase, which is a potent cell motility-stimulating factor) that produces LPA.Invasion is a defining hallmark of GBM. LPA is significantly related to cell adhesion, cell motility, and invasion through the Rho family GTPases Rho and Rac. LPA1 is responsible for LPA-driven cell motility, which is attenuated by LPA4. GBM is among the most vascular human tumors. Although anti-angiogenic therapy (through the inhibition of vascular endothelial growth factor (VEGF)) was established, sufficient results have not been obtained because of the increased invasiveness triggered by anti-angiogenesis. As both ATX and LPA play a significant role in angiogenesis, similar to VEGF, inhibition of the ATX/LPA axis may be beneficial as a two-pronged therapy that includes anti-angiogenic and anti-invasion therapy. Conventional approaches to GBM are predominantly directed at cell proliferation. Recurrent tumors regrow from cells that have invaded brain tissues and are less proliferative, and are thus quite resistant to conventional drugs and radiation, which preferentially kill rapidly proliferating cells. A novel approach that targets this invasive subpopulation of GBM cells may improve the prognosis of GBM. Patients with GBM that

  16. A novel lysophosphatidic acid acyltransferase enzyme (LPAAT4) with a possible role for incorporating docosahexaenoic acid into brain glycerophospholipids.

    PubMed

    Eto, Miki; Shindou, Hideo; Shimizu, Takao

    2014-01-10

    Glycerophospholipids are important components of cellular membranes, required for constructing structural barriers, and for providing precursors of bioactive lipid mediators. Lysophosphatidic acid acyltransferases (LPAATs) are enzymes known to function in the de novo glycerophospholipid biosynthetic pathway (Kennedy pathway), using lysophosphatidic acid (LPA) and acyl-CoA to form phosphatidic acid (PA). Until now, three LPAATs (LPAAT1, 2, and 3) have been reported from the 1-acyl-glycerol-3-phosphate O-acyltransferase (AGPAT) family. In this study, we identified a fourth LPAAT enzyme, LPAAT4, previously known as an uncharacterized enzyme AGPAT4 (LPAATδ), from the AGPAT family. Although LPAAT4 was known to contain AGPAT motifs essential for acyltransferase activities, detailed biochemical properties were unknown. Here, we found that mouse LPAAT4 (mLPAAT4) possesses LPAAT activity with high acyl-CoA specificity for polyunsaturated fatty acyl-CoA, especially docosahexaenoyl-CoA (22:6-CoA, DHA-CoA). mLPAAT4 was distributed in many tissues, with relatively high expression in the brain, rich in docosahexaenoic acid (DHA, 22:6). mLPAAT4 siRNA in a neuronal cell line, Neuro 2A, caused a decrease in LPAAT activity with 22:6-CoA, suggesting that mLPAAT4 functions endogenously. siRNA in Neuro 2A cells caused a decrease in 18:0-22:6 PC, whereas mLPAAT4 overexpression in Chinese hamster ovary (CHO)-K1 cells caused an increase in this species. Although DHA is considered to have many important functions for the brain, the mechanism of its incorporation into glycerophospholipids is unknown. LPAAT4 might have a significant role for maintaining DHA in neural membranes. Identification of LPAAT4 will possibly contribute to understanding the regulation and the biological roles of DHA-containing glycerophospholipids in the brain. Copyright © 2013 The Authors. Published by Elsevier Inc. All rights reserved.

  17. Lysophosphatidic acid induces cell migration through the selective activation of Akt1

    PubMed Central

    Kim, Eun Kyoung; Yun, Sung Ji; Do, Kee Hun; Kim, Min Sung; Cho, Mong; Suh, Dong-Soo; Kim, Chi Dae; Kim, Jae Ho; Birnbaum, Morris J.

    2008-01-01

    Akt plays pivotal roles in many physiological responses including growth, proliferation, survival, metabolism, and migration. In the current studies, we have evaluated the isoform-specific role of akt in lysophosphatidic acid (LPA)-induced cell migration. Ascites from ovarian cancer patients (AOCP) induced mouse embryo fibroblast (MEF) cell migration in a dose-dependent manner. On the other hand, ascites from liver cirrhosis patients (ALCP) did not induce MEF cell migration. AOCP-induced MEF cell migration was completely blocked by pre-treatment of cells with LPA receptor antagonist, Ki16425. Both LPA- and AOCP-induced MEF cell migration was completely attenuated by PI3K inhibitor, LY294002. Furthermore, cells lacking Akt1 displayed defect in LPA-induced cell migration. Re-expression of Akt1 in DKO (Akt1-/-Akt2-/-) cells restored LPA-induced cell migration, whereas re-expression of Akt2 in DKO cells could not restore the LPA-induced cell migration. Finally, Akt1 was selectively phosphorylated by LPA and AOCP stimulation. These results suggest that LPA is a major factor responsible for AOCP-induced cell migration and signaling specificity of Akt1 may dictate LPA-induced cell migration. PMID:18779657

  18. LYSOPHOSPHATIDIC ACID INHIBITS CD8 T CELL ACTIVATION AND CONTROL OF TUMOR PROGRESSION

    PubMed Central

    Oda, Shannon K.; Strauch, Pamela; Fujiwara, Yuko; Al-Shami, Amin; Oravecz, Tamas; Tigyi, Gabor; Pelanda, Roberta; Torres, Raul M.

    2013-01-01

    CD8 T lymphocytes are able to eliminate nascent tumor cells through a process referred to as immune surveillance. However, multiple inhibitory mechanisms within the tumor microenvironment have been described that impede tumor rejection by CD8 T cells, including increased signaling by inhibitory receptors. Lysophosphatidic acid (LPA) is a bioactive lysophospholipid that has been shown repeatedly to promote diverse cellular processes benefiting tumorigenesis. Accordingly, the increased expression of LPA and LPA receptors is a common feature of diverse tumor cell lineages and can result in elevated systemic LPA levels. LPA is recognized by at least 6 distinct G-protein-coupled receptors and several of which are expressed by T cells, although the precise role of LPA signaling in CD8 T cell activation and function has not been defined. Here, we demonstrate that LPA signaling via the LPA5 receptor expressed by CD8 T cells suppresses antigen receptor signaling, cell activation and proliferation in vitro and in vivo. Importantly, in a mouse melanoma model tumor-specific CD8 T cells that are LPA5-deficient are able to control tumor growth significantly better than wild-type tumor-specific CD8 T cells. Together, these data suggest that the production of LPA by tumors serves not only in an autocrine manner to promote tumorigenesis but also as a mechanism to suppress adaptive immunity and highlights a potential novel target for cancer treatment. PMID:24455753

  19. Lysophosphatidic Acid (LPA) Receptor 5 Inhibits B Cell Antigen Receptor Signaling and Antibody Response1

    PubMed Central

    Shotts, Kristin; Donovan, Erin E.; Strauch, Pamela; Pujanauski, Lindsey M.; Victorino, Francisco; Al-Shami, Amin; Fujiwara, Yuko; Tigyi, Gabor; Oravecz, Tamas; Pelanda, Roberta; Torres, Raul M.

    2014-01-01

    Lysophospholipids have emerged as biologically important chemoattractants capable of directing lymphocyte development, trafficking and localization. Lysophosphatidic acid (LPA) is a major lysophospholipid found systemically and whose levels are elevated in certain pathological settings such as cancer and infections. Here, we demonstrate that BCR signal transduction by mature murine B cells is inhibited upon LPA engagement of the LPA5 (GPR92) receptor via a Gα12/13 – Arhgef1 pathway. The inhibition of BCR signaling by LPA5 manifests by impaired intracellular calcium store release and most likely by interfering with inositol 1,4,5-trisphosphate receptor activity. We further show that LPA5 also limits antigen-specific induction of CD69 and CD86 expression and that LPA5-deficient B cells display enhanced antibody responses. Thus, these data show that LPA5 negatively regulates BCR signaling, B cell activation and immune response. Our findings extend the influence of lysophospholipids on immune function and suggest that alterations in LPA levels likely influence adaptive humoral immunity. PMID:24890721

  20. Lysophosphatidic Acid is a Modulator of Cyst Growth in Autosomal Dominant Polycystic Kidney Disease

    PubMed Central

    Blazer-Yost, Bonnie L.; Blacklock, Brenda J.; Flaig, Stephanie; Bacallao, Robert L.; Gattone, Vincent H.

    2011-01-01

    Autosomal dominant polycystic kidney disease (ADPKD) is characterized by the slow growth of multiple fluid-filled cysts predominately in the kidney tubules and liver bile ducts. Elucidation of mechanisms that control cyst growth will provide the basis for rational therapeutic intervention. We used electrophysiological methods to identify lysophosphatidic acid (LPA) as a component of cyst fluid and serum that stimulates secretory Cl- transport in the epithelial cell type that lines renal cysts. LPA effects are manifested through receptors located on the basolateral membrane of the epithelial cells resulting in stimulation of channel activity in the apical membrane. Concentrations of LPA measured in human ADPKD cyst fluid and in normal serum are sufficient to maximally stimulate ion transport. Thus, cyst fluid seepage and/or leakage of vascular LPA into the interstitial space are capable of stimulating epithelial cell secretion resulting in cyst enlargement. These observations are particularly relevant to the rapid decline in renal function in late-stage disease and to the “third hit” hypothesis that renal injury exacerbates cyst growth. PMID:22179013

  1. Mechanism of rapid elimination of lysophosphatidic acid and related lipids from the circulation of mice

    PubMed Central

    Salous, Abdel K.; Panchatcharam, Manikandan; Sunkara, Manjula; Mueller, Paul; Dong, Anping; Wang, Yuhuan; Graf, Gregory A.; Smyth, Susan S.; Morris, Andrew J.

    2013-01-01

    Lysophosphatidic acid (LPA) is a bioactive lipid mediator. Concentrations of the major LPA species in mouse plasma decreased uniformly following administration of a potent selective inhibitor of the LPA-generating lysophospholipase D autotaxin, identifying an active mechanism for removal of LPA from the circulation. LPA, akylglycerol phosphate (AGP), sphingosine 1-phosphate (S1P), and a variety of structural mimetics of these lipids, including phosphatase-resistant phosphonate analogs of LPA, were rapidly eliminated (t1/2 < 30 s) from the circulation of mice following intravenous administration of a single bolus dose without significant metabolism in situ in the blood. These lipids accumulated in the liver. Elimination of intravenously administered LPA was blunted by ligation of the hepatic circulation, and ∼90% of LPA administered through the portal vein was accumulated by the isolated perfused mouse liver at first pass. At early times following intravenous administration, more LPA was associated with a nonparenchymal liver cell fraction than with hepatocytes. Primary cultures of nonparenchymal liver cells rapidly assimilated exogenously provided LPA. Our results identify hepatic uptake as an important determinant of the bioavailability of LPA and bioactive lysophospholipid mimetics and suggest a mechanism to explain changes in circulating LPA levels that have been associated with liver dysfunction in humans. PMID:23948545

  2. Platelet-derived lysophosphatidic acid supports the progression of osteolytic bone metastases in breast cancer

    PubMed Central

    Boucharaba, Ahmed; Serre, Claire-Marie; Grès, Sandra; Saulnier-Blache, Jean Sébastien; Bordet, Jean-Claude; Guglielmi, Julien; Clézardin, Philippe; Peyruchaud, Olivier

    2004-01-01

    The role of lysophosphatidic acid (LPA) in cancer is poorly understood. Here we provide evidence for a role of LPA in the progression of breast cancer bone metastases. LPA receptors LPA1, LPA2, and LPA3 were expressed in human primary breast tumors and a series of human breast cancer cell lines. The inducible overexpression of LPA1 in MDA-BO2 breast cancer cells specifically sensitized these cells to the mitogenic action of LPA in vitro. In vivo, LPA1 overexpression in MDA-BO2 cells enhanced the growth of subcutaneous tumor xenografts and promoted bone metastasis formation in mice by increasing both skeletal tumor growth and bone destruction. This suggested that endogenous LPA was produced in the tumor microenvironment. However, MDA-BO2 cells or transfectants did not produce LPA. Instead, they induced the release of LPA from activated platelets which, in turn, promoted tumor cell proliferation and the LPA1-dependent secretion of IL-6 and IL-8, 2 potent bone resorption stimulators. Moreover, platelet-derived LPA deprivation in mice, achieved by treatment with the platelet antagonist Integrilin, inhibited the progression of bone metastases caused by parental and LPA1-overexpressing MDA-BO2 cells and reduced the progression of osteolytic lesions in mice bearing CHO-β3wt ovarian cancer cells. Overall, our data suggest that, at the bone metastatic site, tumor cells stimulate the production of LPA from activated platelets, which enhances both tumor growth and cytokine-mediated bone destruction. PMID:15599396

  3. Adipose-specific disruption of autotaxin enhances nutritional fattening and reduces plasma lysophosphatidic acid

    PubMed Central

    Dusaulcy, Rodolphe; Rancoule, Chloé; Grès, Sandra; Wanecq, Estelle; Colom, André; Guigné, Charlotte; van Meeteren, Laurens A.; Moolenaar, Wouter H.; Valet, Philippe; Saulnier-Blache, Jean Sébastien

    2011-01-01

    Autotaxin (ATX) is a secreted lysophospholipase D that generates the lipid mediator lysophosphatidic acid (LPA). ATX is secreted by adipose tissue and its expression is enhanced in obese/insulin-resistant individuals. Here, we analyzed the specific contribution of adipose-ATX to fat expansion associated with nutritional obesity and its consequences on plasma LPA levels. We established ATXF/F/aP2-Cre (FATX-KO) transgenic mice carrying a null ATX allele specifically in adipose tissue. FATX-KO mice and their control littermates were fed either a normal or a high-fat diet (HFD) (45% fat) for 13 weeks. FATX-KO mice showed a strong decrease (up to 90%) in ATX expression in white and brown adipose tissue, but not in other ATX-expressing organs. This was associated with a 38% reduction in plasma LPA levels. When fed an HFD, FATX-KO mice showed a higher fat mass and a higher adipocyte size than control mice although food intake was unchanged. This was associated with increased expression of peroxisome proliferator-activated receptor (PPAR)γ2 and of PPAR-sensitive genes (aP2, adiponectin, leptin, glut-1) in subcutaneous white adipose tissue, as well as in an increased tolerance to glucose. These results show that adipose-ATX is a negative regulator of fat mass expansion in response to an HFD and contributes to plasma LPA levels. PMID:21421848

  4. Adipose-specific disruption of autotaxin enhances nutritional fattening and reduces plasma lysophosphatidic acid.

    PubMed

    Dusaulcy, Rodolphe; Rancoule, Chloé; Grès, Sandra; Wanecq, Estelle; Colom, André; Guigné, Charlotte; van Meeteren, Laurens A; Moolenaar, Wouter H; Valet, Philippe; Saulnier-Blache, Jean Sébastien

    2011-06-01

    Autotaxin (ATX) is a secreted lysophospholipase D that generates the lipid mediator lysophosphatidic acid (LPA). ATX is secreted by adipose tissue and its expression is enhanced in obese/insulin-resistant individuals. Here, we analyzed the specific contribution of adipose-ATX to fat expansion associated with nutritional obesity and its consequences on plasma LPA levels. We established ATX(F/F)/aP2-Cre (FATX-KO) transgenic mice carrying a null ATX allele specifically in adipose tissue. FATX-KO mice and their control littermates were fed either a normal or a high-fat diet (HFD) (45% fat) for 13 weeks. FATX-KO mice showed a strong decrease (up to 90%) in ATX expression in white and brown adipose tissue, but not in other ATX-expressing organs. This was associated with a 38% reduction in plasma LPA levels. When fed an HFD, FATX-KO mice showed a higher fat mass and a higher adipocyte size than control mice although food intake was unchanged. This was associated with increased expression of peroxisome proliferator-activated receptor (PPAR)γ2 and of PPAR-sensitive genes (aP2, adiponectin, leptin, glut-1) in subcutaneous white adipose tissue, as well as in an increased tolerance to glucose. These results show that adipose-ATX is a negative regulator of fat mass expansion in response to an HFD and contributes to plasma LPA levels.

  5. Platelet-derived lysophosphatidic acid supports the progression of osteolytic bone metastases in breast cancer.

    PubMed

    Boucharaba, Ahmed; Serre, Claire-Marie; Grès, Sandra; Saulnier-Blache, Jean Sébastien; Bordet, Jean-Claude; Guglielmi, Julien; Clézardin, Philippe; Peyruchaud, Olivier

    2004-12-01

    The role of lysophosphatidic acid (LPA) in cancer is poorly understood. Here we provide evidence for a role of LPA in the progression of breast cancer bone metastases. LPA receptors LPA(1), LPA(2), and LPA(3) were expressed in human primary breast tumors and a series of human breast cancer cell lines. The inducible overexpression of LPA(1) in MDA-BO2 breast cancer cells specifically sensitized these cells to the mitogenic action of LPA in vitro. In vivo, LPA(1) overexpression in MDA-BO2 cells enhanced the growth of subcutaneous tumor xenografts and promoted bone metastasis formation in mice by increasing both skeletal tumor growth and bone destruction. This suggested that endogenous LPA was produced in the tumor microenvironment. However, MDA-BO2 cells or transfectants did not produce LPA. Instead, they induced the release of LPA from activated platelets which, in turn, promoted tumor cell proliferation and the LPA(1)-dependent secretion of IL-6 and IL-8, 2 potent bone resorption stimulators. Moreover, platelet-derived LPA deprivation in mice, achieved by treatment with the platelet antagonist Integrilin, inhibited the progression of bone metastases caused by parental and LPA(1)-overexpressing MDA-BO2 cells and reduced the progression of osteolytic lesions in mice bearing CHO-beta3wt ovarian cancer cells. Overall, our data suggest that, at the bone metastatic site, tumor cells stimulate the production of LPA from activated platelets, which enhances both tumor growth and cytokine-mediated bone destruction.

  6. Activation of Lysophosphatidic Acid Receptor Type 1 Contributes to Pathophysiology of Spinal Cord Injury

    PubMed Central

    Santos-Nogueira, Eva; López-Serrano, Clara; Hernández, Joaquim; Lago, Natalia; Astudillo, Alma M.; Balsinde, Jesús; Estivill-Torrús, Guillermo; de Fonseca, Fernando Rodriguez; Chun, Jerold

    2015-01-01

    Lysophosphatidic acid (LPA) is an extracellular lipid mediator involved in many physiological functions that signals through six known G-protein-coupled receptors (LPA1–LPA6). A wide range of LPA effects have been identified in the CNS, including neural progenitor cell physiology, astrocyte and microglia activation, neuronal cell death, axonal retraction, and development of neuropathic pain. However, little is known about the involvement of LPA in CNS pathologies. Herein, we demonstrate for the first time that LPA signaling via LPA1 contributes to secondary damage after spinal cord injury. LPA levels increase in the contused spinal cord parenchyma during the first 14 d. To model this potential contribution of LPA in the spinal cord, we injected LPA into the normal spinal cord, revealing that LPA induces microglia/macrophage activation and demyelination. Use of a selective LPA1 antagonist or mice lacking LPA1 linked receptor-mediated signaling to demyelination, which was in part mediated by microglia. Finally, we demonstrate that selective blockade of LPA1 after spinal cord injury results in reduced demyelination and improvement in locomotor recovery. Overall, these results support LPA–LPA1 signaling as a novel pathway that contributes to secondary damage after spinal cord contusion in mice and suggest that LPA1 antagonism might be useful for the treatment of acute spinal cord injury. SIGNIFICANCE STATEMENT This study reveals that LPA signaling via LPA receptor type 1 activation causes demyelination and functional deficits after spinal cord injury. PMID:26180199

  7. Distribution of Endogenous Farnesyl Pyrophosphate and Four Species of Lysophosphatidic Acid in Rodent Brain

    PubMed Central

    Lee, Sung Ha; Raboune, Siham; Walker, J. Michael; Bradshaw, Heather B.

    2010-01-01

    Lysophosphatidic acid (LPA) is the umbrella term for lipid signaling molecules that share structural homology and activate the family of LPA receptors. Farnesyl Pyrophosphate (FPP) is commonly known as an intermediate in the synthesis of steroid hormones; however, its function as a signaling lipid is beginning to be explored. FPP was recently shown to an activator of the G-protein coupled receptor 92 (also known as LPA5) of the calcium channel TRPV3. The LPA receptors (including GPR92) are associated with the signal transduction of noxious stimuli, however, very little is known about the distribution of their signaling ligands (LPAs and FPP) in the brain. Here, using HPLC/MS/MS, we developed extraction and analytical methods for measuring levels of FPP and 4 species of LPA (palmitoyl, stearoyl, oleoyl and arachidonoyl-sn-glycerol-3 phosphate) in rodent brain. Relative distributions of each of the five compounds was significantly different across the brain suggesting divergent functionality for each as signaling molecules based on where and how much of each is being produced. Brainstem, midbrain, and thalamus contained the highest levels measured for each compound, though none in the same ratios while relatively small amounts were produced in cortex and cerebellum. These data provide a framework for investigations into functional relationships of these lipid ligands in specific brain areas, many of which are associated with the perception of pain. PMID:21152313

  8. A painful link between the TRPV1 channel and lysophosphatidic acid.

    PubMed

    Morales-Lázaro, Sara L; Rosenbaum, Tamara

    2015-03-15

    The Transient Receptor Potential Vanilloid 1 (TRPV1) ion channel is expressed mainly by sensory neurons that detect noxious stimuli from the environment such as high temperatures and pungent compounds (such as allicin and capsaicin) and has been extensively linked to painful and inflammatory processes. This extraordinary protein also responds to endogenous stimuli among which we find molecules of a lipidic nature. We recently described that lysophosphatidic acid (LPA), a bioactive lysophospholipid linked to the generation and maintenance of pain, can directly activate TRPV1 and produce pain by binding to the channels' C-terminal region, specifically to residue K710. In an effort to further understand how activation of TRPV1 is achieved by this negatively-charged lipid, we used several synthetic and naturally-occurring lipids to determine the structural requirements that need to be met by these charged lipids in order to produce the activation of TRPV1. In this review, we detail the findings obtained by other research groups and our own on the field of TRPV1-regulation by negatively-charged lipids and discuss the possible therapeutic relevance of these findings on the basis of the role of TRPV1 in pathophysiological processes.

  9. Mitogenic action of lysophosphatidic acid in proximal tubular epithelial cells obtained from voided human urine.

    PubMed

    Kumagai, N; Inoue, C N; Kondo, Y; Iinuma, K

    2000-12-01

    Focal tubular cell multiplication at sites on an injured nephron is a critical event in the recovery phase following acute tubular necrosis. During this process, numerous viable tubular cells exfoliate and are shed into the urine. Lysophosphatidic acid (LPA) is generated in the plasma membrane of injured cells and acts as an intercellular mediator of various biological processes, including inflammation, proliferation and repair. In the present study, exfoliated proximal tubule (PT) cells were isolated from human urine and the mitogenic effects of LPA were investigated as a model of repair and proliferation following renal injury. LPA stimulated a 23. 5% increase in DNA synthesis, a 29.4% increase in cell number and an 86.6% decrease in cAMP content. All of these responses were pertussis toxin sensitive, indicating the involvement of G(i)-type G-proteins in LPA signalling. Conversely, the LPA-induced DNA synthesis and the decrease in intracellular cAMP content were insensitive to wortmannin, an inhibitor of phosphatidylinositol 3-kinase (PI3K), suggesting a mitogenic response via PI3K-independent mechanisms. Furthermore, we detected specific mRNA transcripts for the recently cloned human LPA-receptors, endothelial differentiation gene (Edg)-2 and Edg-4 (Edg-2>Edg-4) by reverse transcription-PCR in PT cells. Our data suggest that LPA may behave as a local growth factor in PT cells following tubular injury.

  10. 1-Oleoyl Lysophosphatidic Acid: A New Mediator of Emotional Behavior in Rats

    PubMed Central

    Castilla-Ortega, Estela; Escuredo, Leticia; Bilbao, Ainhoa; Pedraza, Carmen; Orio, Laura; Estivill-Torrús, Guillermo; Santín, Luis J.; de Fonseca, Fernando Rodríguez; Pavón, Francisco Javier

    2014-01-01

    The role of lysophosphatidic acid (LPA) in the control of emotional behavior remains to be determined. We analyzed the effects of the central administration of 1-oleoyl-LPA (LPA 18∶1) in rats tested for food consumption and anxiety-like and depression-like behaviors. For this purpose, the elevated plus-maze, open field, Y maze, forced swimming and food intake tests were performed. In addition, c-Fos expression in the dorsal periaqueductal gray matter (DPAG) was also determined. The results revealed that the administration of LPA 18∶1 reduced the time in the open arms of the elevated plus-maze and induced hypolocomotion in the open field, suggesting an anxiogenic-like phenotype. Interestingly, these effects were present following LPA 18∶1 infusion under conditions of novelty but not under habituation conditions. In the forced swimming test, the administration of LPA 18∶1 dose-dependently increased depression-like behavior, as evaluated according to immobility time. LPA treatment induced no effects on feeding. However, the immunohistochemical analysis revealed that LPA 18∶1 increased c-Fos expression in the DPAG. The abundant expression of the LPA1 receptor, one of the main targets for LPA 18∶1, was detected in this brain area, which participates in the control of emotional behavior, using immunocytochemistry. These findings indicate that LPA is a relevant transmitter potentially involved in normal and pathological emotional responses, including anxiety and depression. PMID:24409327

  11. Rapid and reversible enhancement of blood–brain barrier permeability using lysophosphatidic acid

    PubMed Central

    On, Ngoc H; Savant, Sanjot; Toews, Myron; Miller, Donald W

    2013-01-01

    The present study characterizes the effects of lysophosphatidic acid (LPA) on blood–brain barrier (BBB) permeability focusing specifically on the time of onset, duration, and magnitude of LPA-induced changes in cerebrovascular permeability in the mouse using both magnetic resonance imaging (MRI) and near infrared fluorescence imaging (NIFR). Furthermore, potential application of LPA for enhanced drug delivery to the brain was also examined by measuring the brain accumulation of radiolabeled methotrexate. Exposure of primary cultured brain microvessel endothelial cells (BMECs) to LPA produced concentration-dependent increases in permeability that were completely abolished by clostridium toxin B. Administration of LPA disrupted BBB integrity and enhanced the permeability of small molecular weight marker gadolinium diethylenetriaminepentaacetate (Gd-DTPA) contrast agent, the large molecular weight permeability marker, IRdye800cwPEG, and the P-glycoprotein efflux transporter probe, Rhodamine 800 (R800). The increase in BBB permeability occurred within 3 minutes after LPA injection and barrier integrity was restored within 20 minutes. A decreased response to LPA on large macromolecule BBB permeability was observed after repeated administration. The administration of LPA also resulted in 20-fold enhancement of radiolabeled methotrexate in the brain. These studies indicate that administration of LPA in combination with therapeutic agents may increase drug delivery to the brain. PMID:24045401

  12. Lysophosphatidic acid stimulates thrombomodulin lectin-like domain shedding in human endothelial cells

    SciTech Connect

    Wu Hualin; Lin ChiIou; Huang Yuanli; Chen, Pin-Shern; Kuo, Cheng-Hsiang; Chen, Mei-Shing; Wu, G.C.-C.; Shi, G.-Y.; Yang, H.-Y.; Lee Hsinyu

    2008-02-29

    Thrombomodulin (TM) is an anticoagulant glycoprotein highly expressed on endothelial cell surfaces. Increased levels of soluble TM in circulation have been widely accepted as an indicator of endothelial damage or dysfunction. Previous studies indicated that various proinflammatory factors stimulate TM shedding in various cell types such as smooth muscle cells and epithelial cells. Lysophosphatidic acid (LPA) is a bioactive lipid mediator present in biological fluids during endothelial damage or injury. In the present study, we first observed that LPA triggered TM shedding in human umbilical vein endothelial cells (HUVECs). By Cyflow analysis, we showed that the LPA-induced accessibility of antibodies to the endothelial growth factor (EGF)-like domain of TM is independent of matrix metalloproteinases (MMPs), while LPA-induced TM lectin-like domain shedding is MMP-dependent. Furthermore, a stable cell line expressing TM without its lectin-like domain exhibited a higher cell proliferation rate than a stable cell line expressing full-length TM. These results imply that LPA induces TM lectin-like domain shedding, which might contribute to the exposure of its EGF-like domain for EGF receptor (EGFR) binding, thereby stimulating subsequent cell proliferation. Based on our findings, we propose a novel mechanism for the exposure of TM EGF-like domain, which possibly mediates LPA-induced EGFR transactivation.

  13. Steroid binding to Autotaxin links bile salts and lysophosphatidic acid signalling

    PubMed Central

    Keune, Willem-Jan; Hausmann, Jens; Bolier, Ruth; Tolenaars, Dagmar; Kremer, Andreas; Heidebrecht, Tatjana; Joosten, Robbie P.; Sunkara, Manjula; Morris, Andrew J.; Matas-Rico, Elisa; Moolenaar, Wouter H.; Oude Elferink, Ronald P.; Perrakis, Anastassis

    2016-01-01

    Autotaxin (ATX) generates the lipid mediator lysophosphatidic acid (LPA). ATX-LPA signalling is involved in multiple biological and pathophysiological processes, including vasculogenesis, fibrosis, cholestatic pruritus and tumour progression. ATX has a tripartite active site, combining a hydrophilic groove, a hydrophobic lipid-binding pocket and a tunnel of unclear function. We present crystal structures of rat ATX bound to 7α-hydroxycholesterol and the bile salt tauroursodeoxycholate (TUDCA), showing how the tunnel selectively binds steroids. A structure of ATX simultaneously harbouring TUDCA in the tunnel and LPA in the pocket, together with kinetic analysis, reveals that bile salts act as partial non-competitive inhibitors of ATX, thereby attenuating LPA receptor activation. This unexpected interplay between ATX-LPA signalling and select steroids, notably natural bile salts, provides a molecular basis for the emerging association of ATX with disorders associated with increased circulating levels of bile salts. Furthermore, our findings suggest potential clinical implications in the use of steroid drugs. PMID:27075612

  14. Atherosclerotic Lesion Progression Changes Lysophosphatidic Acid Homeostasis to Favor its Accumulation

    PubMed Central

    Bot, Martine; Bot, Ilze; Lopez-Vales, Rubén; van de Lest, Chris H.A.; Saulnier-Blache, Jean Sébastien; Helms, J. Bernd; David, Samuel; van Berkel, Theo J.C.; Biessen, Erik A.L.

    2010-01-01

    Lysophosphatidic acid (LPA) accumulates in the central atheroma of human atherosclerotic plaques and is the primary platelet-activating lipid constituent of plaques. Here, we investigated the enzymatic regulation of LPA homeostasis in atherosclerotic lesions at various stages of disease progression. Atherosclerotic lesions were induced in carotid arteries of low-density lipoprotein receptor–deficient mice by semiconstrictive collar placement. At 2-week intervals after collar placement, lipids and RNA were extracted from the vessel segments carrying the plaque. Enzymatic-and liquid chromatography-mass spectrometry–based lipid profiling revealed progressive accumulation of LPA species in atherosclerotic tissue preceded by an increase in lysophosphatidylcholine, a precursor in LPA synthesis. Plaque expression of LPA-generating enzymes cytoplasmic phospholipase A2IVA (cPLA2IVA) and calcium-independent PLA2VIA (iPLA2VIA) was gradually increased, whereas that of the LPA-hydrolyzing enzyme LPA acyltransferase α was quenched. Increased expression of cPLA2IVA and iPLA2VIA in advanced lesions was confirmed by immunohistochemistry. Moreover, LPA receptors 1 and 2 were 50% decreased and sevenfold upregulated, respectively. Therefore, key proteins in LPA homeostasis are increasingly dysregulated in the plaque during atherogenesis, favoring intracellular LPA production. This might at least partly explain the observed progressive accumulation of this thrombogenic proinflammatory lipid in human and mouse plaques. Thus, intervention in the enzymatic LPA production may be an attractive measure to lower intraplaque LPA content, thereby reducing plaque progression and thrombogenicity. PMID:20431029

  15. Differently Localized Lysophosphatidic Acid Acyltransferases Crucial for Triacylglycerol Biosynthesis in the Oleaginous Alga Nannochloropsis.

    PubMed

    Nobusawa, Takashi; Hori, Koichi; Mori, Hiroshi; Kurokawa, Ken; Ohta, Hiroyuki

    2017-02-20

    Production of renewable bioenergy will be necessary to meet rising global fossil fuel demands. Members of the marine microalgae genus Nannochloropsis produce large amounts of oils (triacylglycerols; TAGs), and this genus is regarded as one of the most promising for biodiesel production. Recent genome sequencing and transcriptomic studies on Nannochloropsis have provided a foundation for understanding its oleaginous trait, but the mechanism underlying oil accumulation remains to be clarified. Here we report Nannochloropsis knockout strains of four extraplastidic lysophosphatidic acid acyltransferases (LPAT1-4), which catalyze a major de novo biosynthetic step of TAGs and membrane lipids. We found that the four LPATs are differently involved in lipid metabolic flow in Nannochloropsis. Double knockouts among the LPATs revealed the pivotal LPATs for TAG biosynthesis, and localization analysis indicated that the stramenopile-specific LPATs (LPAT3 and LPAT4) associated with TAG synthesis reside at the perimeter of lipid droplets. However, no homologous region has been found with other lipid droplet-associated proteins. Lipid droplets are an organelle found in nearly all organisms, and recently they were shown to play important roles in cellular metabolism and signaling. Our results provide direct evidence for the importance of the perimeter of lipid droplet in TAG synthesis in addition to its known role in maintaining TAG stability, and these findings suggest that the oleaginous trait of Nannochloropsis is enabled by acquisition of LPATs at the perimeter of lipid droplets. This article is protected by copyright. All rights reserved.

  16. Expression of lysophosphatidic acid receptors in the human lower esophageal sphincter

    PubMed Central

    FENG, YONG; LIU, JUN-FENG

    2014-01-01

    Lysophosphatidic acid (LPA) is a bioactive lipid that is involved in a variety of physiological and pathological processes occurring in the gastrointestinal tract. It acts via six distinct types of receptors, LPA1, LPA2, LPA3, LPA4, LPA5 and LPA6, which belong to the family of G protein-coupled receptors. The aim of the present study was to detect the expression of the LPA receptors in the human lower esophageal sphincter (LES). Quantitative polymerase chain reaction and western blotting were used to analyze the expression of LPA1-6 receptors in sling and clasp fibers from the human LES. The results showed that the protein and mRNA expression levels of various LPA receptors were significantly different. Specifically, the mRNA and protein expression levels of the LPA1 receptor were higher compared with those of the other receptors. The prevalence of the LPA1 receptor mRNA and protein indicates that the LPA1 receptor is likely to be involved in the regulation of human LES functions. PMID:24396418

  17. Autocrine lysophosphatidic acid signaling activates β-catenin and promotes lung allograft fibrosis.

    PubMed

    Cao, Pengxiu; Aoki, Yoshiro; Badri, Linda; Walker, Natalie M; Manning, Casey M; Lagstein, Amir; Fearon, Eric R; Lama, Vibha N

    2017-04-03

    Tissue fibrosis is the primary cause of long-term graft failure after organ transplantation. In lung allografts, progressive terminal airway fibrosis leads to an irreversible decline in lung function termed bronchiolitis obliterans syndrome (BOS). Here, we have identified an autocrine pathway linking nuclear factor of activated T cells 2 (NFAT1), autotaxin (ATX), lysophosphatidic acid (LPA), and β-catenin that contributes to progression of fibrosis in lung allografts. Mesenchymal cells (MCs) derived from fibrotic lung allografts (BOS MCs) demonstrated constitutive nuclear β-catenin expression that was dependent on autocrine ATX secretion and LPA signaling. We found that NFAT1 upstream of ATX regulated expression of ATX as well as β-catenin. Silencing NFAT1 in BOS MCs suppressed ATX expression, and sustained overexpression of NFAT1 increased ATX expression and activity in non-fibrotic MCs. LPA signaling induced NFAT1 nuclear translocation, suggesting that autocrine LPA synthesis promotes NFAT1 transcriptional activation and ATX secretion in a positive feedback loop. In an in vivo mouse orthotopic lung transplant model of BOS, antagonism of the LPA receptor (LPA1) or ATX inhibition decreased allograft fibrosis and was associated with lower active β-catenin and dephosphorylated NFAT1 expression. Lung allografts from β-catenin reporter mice demonstrated reduced β-catenin transcriptional activation in the presence of LPA1 antagonist, confirming an in vivo role for LPA signaling in β-catenin activation.

  18. Proliferation of mouse endometrial stromal cells in culture is highly sensitive to lysophosphatidic acid signaling.

    PubMed

    Aikawa, Shizu; Kano, Kuniyuki; Inoue, Asuka; Aoki, Junken

    2017-02-26

    Endometrial stromal cells (ESCs) proliferate rapidly both in vivo and in vitro. Here we show that proliferation of ESCs in vitro is strongly dependent on lysophosphatidic acid (LPA) signaling. LPA is produced by autotaxin (ATX) and induces various kinds of cellular processes including migration, proliferation and inhibition of cell death possibly through six G protein-coupled receptors (LPA1-6). We found that ESCs proliferated rapidly in vitro in an autocrine manner and that the proliferation was prominently suppressed by either an ATX inhibitor (ONO-8430506) or an LPA1/3 antagonist (Ki16425). Among the cells lines tested, mouse ESCs were the most sensitive to these inhibitors. Proliferation of ESCs isolated from either LPA1- or LPA3-deficient mice was comparable to proliferation of ESCs isolated from control mice. An LPA receptor antagonist (AM095), which was revealed to be a dual LPA1/LPA3 antagonist, also suppressed the proliferation of ESCs. The present results show that LPA signaling has a critical role in the proliferation of ESCs, and that this role is possibly mediated redundantly by LPA1 and LPA3. Copyright © 2016. Published by Elsevier Inc.

  19. Lysophosphatidic Acid Synthesis and its Receptors' Expression in the Bovine Oviduct During the Oestrous Cycle.

    PubMed

    Sinderewicz, E; Grycmacher, K; Boruszewska, D; Kowalczyk-Zięba, I; Yamamoto, Y; Yoshimoto, Y; Woclawek-Potocka, I

    2016-08-01

    Lysophosphatidic acid (LPA) is a naturally occurring simple phospholipid which in the bovine reproductive system can be produced in the endometrium, corpus luteum, ovarian follicle and embryo. In this study, we examined the possibility that LPA receptors are expressed, and LPA synthesized, in the bovine oviduct. We found that the concentration of LPA was highest in infundibulum in the follicular phase of the oestrous cycle and was relatively high during the early-luteal phase in all examined parts of the oviduct. We also documented that LPA synthesis engages both available pathways for LPA production. The autotaxin (ATX) protein expression was significantly higher in the infundibulum compared to the isthmus during the follicular phase of the oestrous cycle. During the early-luteal phase of the oestrous cycle, ATX and phospholipase A2 (PLA2) protein expression was highest in ampulla, although the expression of LPARs was not as dynamic as LPA concentration in the oviduct tissue, and we presume that in the bovine oviduct, the most abundantly expressed receptor is LPAR2. In conclusion, our results indicate that the bovine oviduct is a site of LPA synthesis and a target for LPA action in the bovine reproductive tract. We documented that LPAR2 is the most abundantly expressed in the bovine oviduct. We hypothesize that in the bovine oviduct, LPA may be involved in the transport of gametes, fertilization and cellular signalling between the oviduct and cumulus-oocyte complex. © 2016 Blackwell Verlag GmbH.

  20. Activation of TRESK channels by the inflammatory mediator lysophosphatidic acid balances nociceptive signalling.

    PubMed

    Kollert, Sina; Dombert, Benjamin; Döring, Frank; Wischmeyer, Erhard

    2015-07-30

    In dorsal root ganglia (DRG) neurons TRESK channels constitute a major current component of the standing outward current IKSO. A prominent physiological role of TRESK has been attributed to pain sensation. During inflammation mediators of pain e.g. lysophosphatidic acid (LPA) are released and modulate nociception. We demonstrate co-expression of TRESK and LPA receptors in DRG neurons. Heterologous expression of TRESK and LPA receptors in Xenopus oocytes revealed augmentation of basal K(+) currents upon LPA application. In DRG neurons nociception can result from TRPV1 activation by capsaicin or LPA. Upon co-expression in Xenopus oocytes LPA simultaneously increased both depolarising TRPV1 and hyperpolarising TRESK currents. Patch-clamp recordings in cultured DRG neurons from TRESK[wt] mice displayed increased IKSO after application of LPA whereas under these conditions IKSO in neurons from TRESK[ko] mice remained unaltered. Under current-clamp conditions LPA application differentially modulated excitability in these genotypes upon depolarising pulses. Spike frequency was attenuated in TRESK[wt] neurons and, in contrast, augmented in TRESK[ko] neurons. Accordingly, excitation of nociceptive neurons by LPA is balanced by co-activation of TRESK channels. Hence excitation of sensory neurons is strongly controlled by the activity of TRESK channels, which therefore are good candidates for the treatment of pain disorders.

  1. Effects of lysophosphatidic acid and its receptors LPA⅓ on radiation pneumonitis.

    PubMed

    Xue, Jianxin; Gan, Lu; Li, Xin; Li, Jian; Qi, Guohai; Wu, Yalan; Fu, Xiaoyue; Mao, Qing; Ao, Rui; Lang, Jingyi; Lu, You

    2010-12-01

    Radiation pneumonitis (RP) is a serious complication of radiation therapy for thoracic tumors. Lysophosphatidic acid (LPA) and its receptors LPA⅓ were reported to participate in the processes of inflammation. We tested the hypothesis that LPA and its receptors LPA⅓, take part in the pathogenesis of RP. In our study, irradiation increased LPA levels in the lung and expression of LPA⅓. To further determine the role of LPA⅓, we performed pharmacological knockout of LPA⅓ by a specific antagonist, VPC-12249. On day 60 post-irradiation, RP was significantly alleviated in a dose-dependent manner in mice treated with VPC-12249, as shown by H&E staining, malondialdehyde (MDA, an indicator of oxidative damage) assay in lung, and concentrations of proinflammatory and profibrotic cytokines in plasma, including IL-1β, TNF-α, and TGF-β1. Additionally, VPC-12249 administration decreased the phosphorylation of IκB-α (the initial event that activates the NF-κB signal way), and expression of TGF-β1, CTGF, and α-SMA mRNA. Our findings suggest that LPA and LPA⅓ may play a pivotal role in RP, and LPA-LPA⅓ may serve as novel therapeutic targets for the treatment of RP.

  2. Studies on lysophosphatidic acid action during in vitro preimplantation embryo development.

    PubMed

    Boruszewska, D; Sinderewicz, E; Kowalczyk-Zieba, I; Grycmacher, K; Woclawek-Potocka, I

    2016-01-01

    Assisted reproductive technologies, including in vitro embryo production (IVP), have been successfully used in animal reproduction to optimize breeding strategies for improved production and health in animal husbandry. Despite the progress in IVP techniques over the years, further improvements in in vitro embryo culture systems are required for the enhancement of oocyte and embryo developmental competence. One of the most important issues associated with IVP procedures is the optimization of the in vitro culture of oocytes and embryos. Studies in different species of animals and in humans have identified important roles for receptor-mediated lysophosphatidic acid (LPA) signaling in multiple aspects of human and animal reproductive tract function. The data on LPA signaling in the ovary and uterus suggest that LPA can directly contribute to embryo-maternal interactions via its influence on early embryo development beginning from the influence of the ovarian environment on the oocyte to the influence of the uterine environment on the preimplantation embryo. This review discusses the current status of LPA as a potential supplement in oocyte maturation, fertilization, and embryo culture media and current views on the potential involvement of the LPA signaling pathway in early embryo development. Copyright © 2016 Elsevier Inc. All rights reserved.

  3. G-Protein-Coupled Lysophosphatidic Acid Receptors and Their Regulation of AKT Signaling

    PubMed Central

    Riaz, Anjum; Huang, Ying; Johansson, Staffan

    2016-01-01

    A hallmark of G-protein-coupled receptors (GPCRs) is their ability to recognize and respond to chemically diverse ligands. Lysophospholipids constitute a relatively recent addition to these ligands and carry out their biological functions by activating G-proteins coupled to a large family of cell-surface receptors. This review aims to highlight salient features of cell signaling by one class of these receptors, known as lysophosphatidic acid (LPA) receptors, in the context of phosphatidylinositol 3-kinase (PI3K)–AKT pathway activation. LPA moieties efficiently activate AKT phosphorylation and activation in a multitude of cell types. The interplay between LPA, its receptors, the associated Gαi/o subunits, PI3K and AKT contributes to the regulation of cell survival, migration, proliferation and confers chemotherapy-resistance in certain cancers. However, detailed information on the regulation of PI3K–AKT signals induced by LPA receptors is missing from the literature. Here, some urgent issues for investigation are highlighted. PMID:26861299

  4. Autotaxin-Lysophosphatidic Acid Axis Acts Downstream of Apoprotein B Lipoproteins in Endothelial Cells.

    PubMed

    Gibbs-Bar, Liron; Tempelhof, Hanoch; Ben-Hamo, Rotem; Ely, Yona; Brandis, Alexander; Hofi, Roy; Almog, Gabriella; Braun, Tslil; Feldmesser, Ester; Efroni, Sol; Yaniv, Karina

    2016-10-01

    As they travel through the blood stream, plasma lipoproteins interact continuously with endothelial cells (ECs). Although the focus of research has mostly been guided by the importance of lipoproteins as risk factors for atherosclerosis, thrombosis, and other cardiovascular diseases, little is known about the mechanisms linking lipoproteins and angiogenesis under physiological conditions, and particularly, during embryonic development. In this work, we performed global mRNA expression profiling of endothelial cells from hypo-, and hyperlipidemic zebrafish embryos with the goal of uncovering novel mediators of lipoprotein signaling in the endothelium. Microarray analysis was conducted on fluorescence-activated cell sorting-isolated fli1:EGFP(+) ECs from normal, hypo-, and hyperlipidemic zebrafish embryos. We found that opposed levels of apoprotein B lipoproteins result in differential expression of the secreted enzyme autotaxin in ECs, which in turn affects EC sprouting and angiogenesis. We further demonstrate that the effects of autotaxin in vivo are mediated by lysophosphatidic acid (LPA)-a well-known autotaxin activity product-and that LPA and LPA receptors participate as well in the response of ECs to lipoprotein levels. Our findings provide the first in vivo gene expression profiling of ECs facing different levels of plasma apoprotein B lipoproteins and uncover a novel lipoprotein-autotaxin-LPA axis as regulator of EC behavior. These results highlight new roles for lipoproteins as signaling molecules, which are independent of their canonical function as cholesterol transporters. © 2016 American Heart Association, Inc.

  5. G-Protein-Coupled Lysophosphatidic Acid Receptors and Their Regulation of AKT Signaling.

    PubMed

    Riaz, Anjum; Huang, Ying; Johansson, Staffan

    2016-02-05

    A hallmark of G-protein-coupled receptors (GPCRs) is their ability to recognize and respond to chemically diverse ligands. Lysophospholipids constitute a relatively recent addition to these ligands and carry out their biological functions by activating G-proteins coupled to a large family of cell-surface receptors. This review aims to highlight salient features of cell signaling by one class of these receptors, known as lysophosphatidic acid (LPA) receptors, in the context of phosphatidylinositol 3-kinase (PI3K)-AKT pathway activation. LPA moieties efficiently activate AKT phosphorylation and activation in a multitude of cell types. The interplay between LPA, its receptors, the associated Gαi/o subunits, PI3K and AKT contributes to the regulation of cell survival, migration, proliferation and confers chemotherapy-resistance in certain cancers. However, detailed information on the regulation of PI3K-AKT signals induced by LPA receptors is missing from the literature. Here, some urgent issues for investigation are highlighted.

  6. Increased urinary lysophosphatidic acid in mouse with subtotal nephrectomy: potential involvement in chronic kidney disease.

    PubMed

    Mirzoyan, Koryun; Baïotto, Anna; Dupuy, Aude; Marsal, Dimitri; Denis, Colette; Vinel, Claire; Sicard, Pierre; Bertrand-Michel, Justine; Bascands, Jean-Loup; Schanstra, Joost P; Klein, Julie; Saulnier-Blache, Jean-Sébastien

    2016-12-01

    Increased incidence of chronic kidney disease (CKD) with consecutive progression to end-stage renal disease represents a significant burden to healthcare systems. Renal tubulointerstitial fibrosis (TIF) is a classical hallmark of CKD and is well correlated with the loss of renal function. The bioactive lysophospholipid lysophosphatidic acid (LPA), acting through specific G-protein-coupled receptors, was previously shown to be involved in TIF development in a mouse model of unilateral ureteral obstruction. Here, we study the role of LPA in a mouse subjected to subtotal nephrectomy (SNx), a more chronic and progressive model of CKD. Five months after surgical nephron reduction, SNx mice showed massive albuminuria, extensive TIF, and glomerular hypertrophy when compared to sham-operated animals. Urinary and plasma levels of LPA were analyzed using liquid chromatography tandem mass spectrometry. LPA was significantly increased in SNx urine, not in plasma, and was significantly correlated with albuminuria and TIF. Moreover, SNx mice showed significant downregulation in the renal expression of lipid phosphate phosphohydrolases (LPP1, 2, and 3) that might be involved in reduced LPA bioavailability through dephosphorylation. We concluded that SNx increases urinary LPA through a mechanism that could involve co-excretion of plasma LPA with albumin associated with a reduction of its catabolism in the kidney. Because of the previously demonstrated profibrotic activity of LPA, the association of urinary LPA with TIF suggests the potential involvement of LPA in the development of advanced CKD in the SNx mouse model. Targeting LPA metabolism might represent an interesting approach in CKD treatment.

  7. Activation of TRESK channels by the inflammatory mediator lysophosphatidic acid balances nociceptive signalling

    PubMed Central

    Kollert, Sina; Dombert, Benjamin; Döring, Frank; Wischmeyer, Erhard

    2015-01-01

    In dorsal root ganglia (DRG) neurons TRESK channels constitute a major current component of the standing outward current IKSO. A prominent physiological role of TRESK has been attributed to pain sensation. During inflammation mediators of pain e.g. lysophosphatidic acid (LPA) are released and modulate nociception. We demonstrate co-expression of TRESK and LPA receptors in DRG neurons. Heterologous expression of TRESK and LPA receptors in Xenopus oocytes revealed augmentation of basal K+ currents upon LPA application. In DRG neurons nociception can result from TRPV1 activation by capsaicin or LPA. Upon co-expression in Xenopus oocytes LPA simultaneously increased both depolarising TRPV1 and hyperpolarising TRESK currents. Patch-clamp recordings in cultured DRG neurons from TRESK[wt] mice displayed increased IKSO after application of LPA whereas under these conditions IKSO in neurons from TRESK[ko] mice remained unaltered. Under current-clamp conditions LPA application differentially modulated excitability in these genotypes upon depolarising pulses. Spike frequency was attenuated in TRESK[wt] neurons and, in contrast, augmented in TRESK[ko] neurons. Accordingly, excitation of nociceptive neurons by LPA is balanced by co-activation of TRESK channels. Hence excitation of sensory neurons is strongly controlled by the activity of TRESK channels, which therefore are good candidates for the treatment of pain disorders. PMID:26224542

  8. The Saccharomyces cerevisiae PHM8 gene encodes a soluble magnesium-dependent lysophosphatidic acid phosphatase.

    PubMed

    Reddy, Venky Sreedhar; Singh, Arjun Kumar; Rajasekharan, Ram

    2008-04-04

    Phosphate is the essential macronutrient required for the growth of all organisms. In Saccharomyces cerevisiae, phosphatases are up-regulated, and the level of lysophosphatidic acid (LPA) is drastically decreased under phosphate-starved conditions. The reduction in the LPA level is attributed to PHM8, a gene of unknown function. phm8Delta yeast showed a decreased LPA-hydrolyzing activity under phosphate-limiting conditions. Overexpression of PHM8 in yeast resulted in an increase in the LPA phosphatase activity in vivo. In vitro assays of the purified recombinant Phm8p revealed magnesium-dependent LPA phosphatase activity, with maximal activity at pH 6.5. The purified Phm8p did not hydrolyze any lipid phosphates other than LPA. In silico analysis suggest that Phm8p is a soluble protein with no transmembrane domain. Site-directed mutational studies revealed that aspartate residues in a DXDXT motif are important for the catalysis. These findings indicated that LPA plays a direct role in phosphate starvation. This is the first report of the identification and characterization of magnesium-dependent soluble LPA phosphatase.

  9. A lysophosphatidic acid analogue is revealed as a potent inhibitor of phosphatidylcholine synthesis, inducing apoptosis.

    PubMed Central

    Gueguen, Geneviéve; Granci, Virginie; Rogalle, Pierre; Briand-Mésange, Fabienne; Wilson, Michéle; Klaébé, Alain; Tercé, François; Chap, Hugues; Salles, Jean-Pierre; Simon, Marie-Françoise; Gaits, Frédérique

    2002-01-01

    A previous study demonstrated that cross-desensitization experiments performed with the lysophosphatidic acid (LPA) analogues (R)- and (S)-N-palmitoyl-norleucinol 1-phosphate (PNPAs) inhibited LPA-induced platelet aggregation without any stereospecificity. Here we report opposite biological effects of the two enantiomers on mitogenesis of IMR-90 fibroblasts in relation to their respective metabolism. (R)PNPA was proliferative, while (S)PNPA induced apoptosis by specifically inhibiting phosphatidylcholine biosynthesis at the last step of the CDP-choline pathway controlled by cholinephosphotransferase. This effect was not direct but required dephosphorylation of PNPAs by ecto-lipid phosphate phosphatase before cellular uptake of the generated N-palmitoyl-norleucinols (PNOHs). Inhibition of cholinephosphotransferase by the derivative (S)PNOH was confirmed by an in vitro assay. (S)PNPA proapoptotic effects led us to clarify the mechanism linking cholinephosphotransferase inhibition to apoptosis. Three proapoptotic responses were observed: the activation of caspase-3, the production of ceramides from newly synthesized pools (as demonstrated by the inhibitor Fumonisin B1) and finally the activation of stress-activated protein kinase, p38 and c-Jun N-terminal kinases 1/2, as a result of ceramide increase. Thus our data demonstrate that synthetic analogues of LPA might display stereospecific effects leading to apoptosis independently of classical LPA-activated pathways. PMID:12197836

  10. Lysophosphatidic acid triggers mast cell-driven atherosclerotic plaque destabilization by increasing vascular inflammation[S

    PubMed Central

    Bot, Martine; de Jager, Saskia C. A.; MacAleese, Luke; Lagraauw, H. Maxime; van Berkel, Theo J. C.; Quax, Paul H. A.; Kuiper, Johan; Heeren, Ron M. A.; Biessen, Erik A. L.; Bot, Ilze

    2013-01-01

    Lysophosphatidic acid (LPA), a bioactive lysophospholipid, accumulates in the atherosclerotic plaque. It has the capacity to activate mast cells, which potentially exacerbates plaque progression. In this study, we thus aimed to investigate whether LPA contributes to plaque destabilization by modulating mast cell function. We here show by an imaging mass spectrometry approach that several LPA species are present in atherosclerotic plaques. Subsequently, we demonstrate that LPA is a potent mast cell activator which, unlike other triggers, favors release of tryptase. Local perivascular administration of LPA to an atherosclerotic carotid artery segment increases the activation status of perivascular mast cells and promotes intraplaque hemorrhage and macrophage recruitment without impacting plaque cell apoptosis. The mast cell stabilizer cromolyn could prevent intraplaque hemorrhage elicited by LPA-mediated mast cell activation. Finally, the involvement of mast cells in these events was further emphasized by the lack of effect of perivascular LPA administration in mast cell deficient animals. We demonstrate that increased accumulation of LPA in plaques induces perivascular mast cell activation and in this way contributes to plaque destabilization in vivo. This study points to local LPA availability as an important factor in atherosclerotic plaque stability. PMID:23396975

  11. Lysophosphatidic acid enhances survival of human CD34+ cells in ischemic conditions

    PubMed Central

    Kostic, Ivana; Fidalgo-Carvalho, Isabel; Aday, Sezin; Vazão, Helena; Carvalheiro, Tiago; Grãos, Mário; Duarte, António; Cardoso, Carla; Gonçalves, Lino; Carvalho, Lina; Paiva, Artur; Ferreira, Lino

    2015-01-01

    Several clinical trials are exploring therapeutic effect of human CD34+ cells in ischemic diseases, including myocardial infarction. Unfortunately, most of the cells die few days after delivery. Herein we show that lysophosphatidic acid (LPA)-treated human umbilical cord blood-derived CD34+ cells cultured under hypoxic and serum-deprived conditions present 2.2-fold and 1.3-fold higher survival relatively to non-treated cells and prostaglandin E2-treated cells, respectively. The pro-survival effect of LPA is concentration- and time-dependent and it is mediated by the activation of peroxisome proliferator-activator receptor γ (PPARγ) and downstream, by the activation of pro-survival ERK and Akt signaling pathways and the inhibition of mitochondrial apoptotic pathway. In hypoxia and serum-deprived culture conditions, LPA induces CD34+ cell proliferation without maintaining the their undifferentiating state, and enhances IL-8, IL-6 and G-CSF secretion during the first 12 h compared to non-treated cells. LPA-treated CD34+ cells delivered in fibrin gels have enhanced survival and improved cardiac fractional shortening at 2 weeks on rat infarcted hearts as compared to hearts treated with placebo. We have developed a new platform to enhance the survival of CD34+ cells using a natural and cost-effective ligand and demonstrated its utility in the preservation of the functionality of the heart after infarction. PMID:26553339

  12. A Metabolically-Stabilized Phosphonate Analog of Lysophosphatidic Acid Attenuates Collagen-Induced Arthritis

    PubMed Central

    Sevastou, Ioanna; Sirioti, Ivi; Samiotaki, Martina; Madan, Damian; Prestwich, Glenn D.; Aidinis, Vassilis

    2013-01-01

    Rheumatoid arthritis (RA) is a destructive arthropathy with systemic manifestations, characterized by chronic synovial inflammation. Under the influence of the pro-inflammatory milieu synovial fibroblasts (SFs), the main effector cells in disease pathogenesis become activated and hyperplastic while releasing a number of signals that include pro-inflammatory factors and tissue remodeling enzymes. Activated RA SFs in mouse or human arthritic joints express significant quantities of autotaxin (ATX), a lysophospholipase D responsible for the majority of lysophosphatidic acid (LPA) production in the serum and inflamed sites. Conditional genetic ablation of ATX from SFs resulted in attenuation of disease symptoms in animal models, an effect attributed to diminished LPA signaling in the synovium, shown to activate SF effector functions. Here we show that administration of 1-bromo-3(S)-hydroxy-4-(palmitoyloxy)butyl-phosphonate (BrP-LPA), a metabolically stabilized analog of LPA and a dual function inhibitor of ATX and pan-antagonist of LPA receptors, attenuates collagen induced arthritis (CIA) development, thus validating the ATX/LPA axis as a novel therapeutic target in RA. PMID:23923032

  13. Effects of lysophosphatidic acid on human colon cancer cells and its mechanisms of action

    PubMed Central

    Sun, Hong; Ren, Juan; Zhu, Qing; Kong, Fan-Zhong; Wu, Lei; Pan, Bo-Rong

    2009-01-01

    AIM: To study the effects of lysophosphatidic acid (LPA) on proliferation, adhesion, migration, and apoptosis in the human colon cancer cell line, SW480, and its mechanisms of action. METHODS: Methyl tetrazolium assay was used to assess cell proliferation. Flow cytometry was employed to detect cell apoptosis. Cell migration was measured by using a Boyden transwell migration chamber. Cell adhesion assay was performed in 96-well plates according to protocol. RESULTS: LPA significantly stimulated SW480 cell proliferation in a dose-dependent and time-dependent manner compared with the control group (P < 0.05) while the mitogen-activated protein kinase (MAPK) inhibitor, PD98059, significantly blocked the LPA stimulation effect on proliferation. LPA also significantly stimulated adhesion and migration of SW480 cells in a dose-dependent manner (P < 0.05). Rho kinase inhibitor, Y-27632, significantly inhibited the up-regulatory effect of LPA on adhesion and migration (P < 0.05). LPA significantly protected cells from apoptosis induced by the chemotherapeutic drugs, cisplatin and 5-FU (P < 0.05), but the phosphoinositide 3-kinase (PI3K) inhibitor, LY294002, significantly blocked the protective effect of LPA on apoptosis. CONCLUSION: LPA stimulated proliferation, adhesion, migration of SW480 cells, and protected from apoptosis. The Ras/Raf-MAPK, G12/13-Rho-RhoA and PI3K-AKT/PKB signal pathways may be involved. PMID:19777613

  14. Lysophosphatidic Acid Inhibits Apoptosis Induced by Cisplatin in Cervical Cancer Cells

    PubMed Central

    Sui, Yanxia; Yang, Ya; Wang, Ji; Li, Yi; Ma, Hongbing; Cai, Hui; Liu, Xiaoping; Zhang, Yong; Wang, Shufeng; Li, Zongfang; Zhang, Xiaozhi; Wang, Jiansheng; Liu, Rui; Yan, Yanli; Xue, Chaofan; Shi, Xiaowei; Tan, Li; Ren, Juan

    2015-01-01

    Cervical cancer is the second most common cause of cancer death in women worldwide. Lysophosphatidic acid (LPA) level has been found significantly increased in the serum of patients with ovarian, cervical, and colon cancers. LPA level in cervical cancer patients is significantly higher than in healthy controls. LPA receptors were found highly expressed in cervical cancer cells, suggesting LPA may play a role in the development of cervical cancer. The aim of this study is to investigate the effect of LPA on the apoptosis induced by cisplatin (DDP) in cervical cancer cell line and the underlying changes in signaling pathways. Our study found that cisplatin induced apoptosis of Hela cell through inhibiting expression of Bcl-2, upregulating the expression of Bax, Fas-L, and the enzyme activity of caspase-3 (p < 0.05); LPA significantly provided protection against the apoptosis induced by cisplatin by inhibiting the above alterations in apoptotic factor caused by cisplatin (p < 0.05). Moreover, PI3K/AKT pathway was found to be important for the LPA antiapoptosis effect, and administration of PI3K/AKT partially reversed the LPA-mediated protection against cisplatin-induced apoptosis (p < 0.05). These findings have shed new lights on the LPA bioactivity in cervical cancer cells and pointed to a possible sensitization scheme through combined administration of PI3K inhibitor and cisplatin for better treatment of cervical cancer patients, especially those with elevated LPA levels. PMID:26366416

  15. Production of lysophosphatidic acid in blister fluid: involvement of a lysophospholipase D activity

    PubMed Central

    Mazereeuw-Hautier, Juliette; Gres, Sandra; Fanguin, Madie; Cariven, Clotilde; Fauvel, Josette; Perret, Bertrand; Chap, Hugues; Salles, Jean-Pierre; Saulnier-Blache, Jean-Sébastien

    2005-01-01

    Lysophosphatidic acid (LPA) is present in abundance in serum resulting from platelet activation and is also found in other biological fluids. LPA controls numerous cellular responses and plays a role in specific functions such as wound healing, especially in the skin. Nevertheless, its presence in the skin has never been investigated during wound healing, or in other situations. Since re-epithelialization occurs after blister rupture, the presence of LPA in blister fluids was investigated. Using a radioenzymatic assay, LPA was detected in 33 blister fluids originating from 24 bullous dermatoses, and at higher concentrations than in plasma. LPA concentration was independent of the type of dermatoses. In parallel, blister fluids contained a lysophospholipase D (LPLD) activity but no detectable phospholipase A2 activity. The expression of the LPLD autotaxin (ATX) and of LPA1-receptor were greatly increased in blister skin when compared to normal skin. Finally, LPA was found to have a positive effect on the migration of cultured keratinocytes. These results show that LPA is present in blister fluid synthesized by the LPLD ATX. Due to its ability to enhance keratinocyte migration, LPA in blister fluid could, via the LPA1-receptor, play an important role in re-epithelialization occuring after blister rupture. PMID:16117781

  16. Production of lysophosphatidic acid in blister fluid: involvement of a lysophospholipase D activity.

    PubMed

    Mazereeuw-Hautier, Juliette; Gres, Sandra; Fanguin, Madie; Cariven, Clotilde; Fauvel, Josette; Perret, Bertrand; Chap, Hugues; Salles, Jean-Pierre; Saulnier-Blache, Jean-Sébastien

    2005-09-01

    Lysophosphatidic acid (LPA) is present in abundance in serum resulting from platelet activation and is also found in other biological fluids. LPA controls numerous cellular responses and plays a role in specific functions such as wound healing, especially in the skin. Nevertheless, its presence in the skin has never been investigated. Since re-epithelialization occurs after blister rupture, we tested the presence of endogenous LPA in blister fluid and investigated a possible mechanism for its biosynthesis and biological functions. Using a radioenzymatic assay, LPA was detected in 33 blister fluids originating from 24 bullous dermatoses, and at higher concentrations than in plasma. In parallel, blister fluids contained a lysophospholipase D (LPLD) activity but no detectable phospholipase A2 activity. The expressions of the LPLD autotaxin (ATX) and of LPA1-receptor (LPA1-R) were greatly increased in blister skin when compared with normal skin. Finally, LPA was found to have a positive effect on the migration of cultured keratinocytes. These results show that LPA is present in blister fluid synthesized by the LPLD ATX. Due to its ability to enhance keratinocyte migration, LPA in blister fluid could, via the LPA1-R, play an important role in re-epithelialization occurring after blister rupture.

  17. Deletion of lysophosphatidic acid receptor LPA1 reduces neurogenesis in the mouse dentate gyrus

    PubMed Central

    Matas-Rico, Elisa; García-Diaz, Beatriz; Llebrez-Zayas, Pedro; López-Barroso, Diana; Santín, Luis; Pedraza, Carmen; Smith-Fernández, Anibal; Fernández-Llebrez, Pedro; Tellez, Teresa; Redondo; Chun, Jerold; De Fonseca, Fernando Rodríguez; Estivill-Torrús, Guillermo

    2013-01-01

    Neurogenesis persists in certain regions of the adult brain including the subgranular zone of the hippocampal dentate gyrus wherein its regulation is essential, particularly in relation to learning, stress and modulation of mood. Lysophosphatidic acid (LPA) is an extracellular signaling phospholipid with important neural regulatory properties mediated by specific G protein-coupled receptors, LPA1-5. LPA1 is highly expressed in the developing neurogenic ventricular zone wherein it is required for normal embryonic neurogenesis, and, by extension may play a role in adult neurogenesis as well. By means of the analyses of a variant of the original LPA1-null mutant mouse, termed the Malaga variant or “maLPA1-null,” which has recently been reported to have defective neurogenesis within the embryonic cerebral cortex, we report here a role for LPA1 in adult hippocampal neurogenesis. Proliferation, differentiation and survival of newly formed neurons are defective in the absence of LPA1 under normal conditions and following exposure to enriched environment and voluntary exercise. Furthermore, analysis of trophic factors in maLPA1-null mice demonstrated alterations in brain-derived neurotrophic factor and insulin growth factor 1 levels after enrichment and exercise. Morphological analyses of doublecortin positive cells revealed the anomalous prevalence of bipolar cells in the subgranular zone, supporting the operation of LPA1 signaling pathways in normal proliferation, maturation and differentiation of neuronal precursors. PMID:18708146

  18. Orally active lysophosphatidic acid receptor antagonist attenuates pancreatic cancer invasion and metastasis in vivo.

    PubMed

    Komachi, Mayumi; Sato, Koichi; Tobo, Masayuki; Mogi, Chihiro; Yamada, Takayuki; Ohta, Hideo; Tomura, Hideaki; Kimura, Takao; Im, Dong-Soon; Yanagida, Keisuke; Ishii, Satoshi; Takeyoshi, Izumi; Okajima, Fumikazu

    2012-06-01

    Pancreatic cancer is highly metastatic and has a poor prognosis. However, there is no established treatment for pancreatic cancer. Lysophosphatidic acid (LPA) has been shown to be present in effluents of cancers and involved in migration and proliferation in a variety of cancer cells, including pancreatic cancer cells, in vitro. In the current study, we examined whether an orally active LPA antagonist is effective for pancreatic cancer tumorigenesis and metastasis in vivo. Oral administration of Ki16198, which is effective for LPA(1) and LPA(3), into YAPC-PD pancreatic cancer cell-inoculated nude mice significantly inhibited tumor weight and remarkably attenuated invasion and metastasis to lung, liver, and brain, in association with inhibition of matrix metalloproteinase (MMP) accumulation in ascites in vivo. Ki16198 inhibited LPA-induced migration and invasion in several pancreatic cancer cells in vitro, which was associated with the inhibition of LPA-induced MMP production. In conclusion, Ki16198 is a promising orally active LPA antagonist for inhibiting the invasion and metastasis of pancreatic cancer cells. The inhibitory effects of the antagonist on invasion and metastasis in vivo may be partially explained by the inhibition of motility activity and MMP production in cancer cells.

  19. Dynamic relocalization of NHERF1 mediates chemotactic migration of ovarian cancer cells toward lysophosphatidic acid stimulation

    PubMed Central

    Oh, Yong-Seok; Heo, Kyun; Kim, Eung-Kyun; Jang, Jin-Hyeok; Bae, Sun Sik; Park, Jong Bae; Kim, Yun Hee; Song, Minseok; Kim, Sang Ryong; Ryu, Sung Ho; Kim, In-Hoo; Suh, Pann-Ghill

    2017-01-01

    NHERF1/EBP50 (Na+/H+ exchanger regulating factor 1; Ezrin-binding phosphoprotein of 50 kDa) organizes stable protein complexes beneath the apical membrane of polar epithelial cells. By contrast, in cancer cells without any fixed polarity, NHERF1 often localizes in the cytoplasm. The regulation of cytoplasmic NHERF1 and its role in cancer progression remain unclear. In this study, we found that, upon lysophosphatidic acid (LPA) stimulation, cytoplasmic NHERF1 rapidly translocated to the plasma membrane, and subsequently to cortical protrusion structures, of ovarian cancer cells. This movement depended on direct binding of NHERF1 to C-terminally phosphorylated ERM proteins (cpERMs). Moreover, NHERF1 depletion downregulated cpERMs and further impaired cpERM-dependent remodeling of the cell cortex, suggesting reciprocal regulation between these proteins. The LPA-induced protein complex was highly enriched in migratory pseudopodia, whose formation was impaired by overexpression of NHERF1 truncation mutants. Consistent with this, NHERF1 depletion in various types of cancer cells abolished chemotactic cell migration toward a LPA gradient. Taken together, our findings suggest that the high dynamics of cytosolic NHERF1 provide cancer cells with a means of controlling chemotactic migration. This capacity is likely to be essential for ovarian cancer progression in tumor microenvironments containing LPA. PMID:28684865

  20. Functional characterization of lysophosphatidic acid receptor 1 mutants identified in rat cancer tissues.

    PubMed

    Ishii, Shoichi; Tsujiuchi, Toshifumi; Fukushima, Nobuyuki

    2017-05-06

    Lysophosphatidic acid (LPA), an extracellular lipid mediator, exerts various cellular effects through activation of LPA receptors, LPA1-LPA6, in many types of cells including cancer cells. We recently found several missense mutations of Lpar1 in rat cancer tissues. One of these mutations is located at the extracellular tip of the seventh transmembrane domain of LPA1, and another three mutations are found within the NPXXY motif in the seventh transmembrane domain. These mutants are designated F295S LPA1 and P308S, I310T, and Y311H LPA1, respectively. Here, we examined the functions of these LPA1 mutants. Compared with wild-type (WT) LPA1, F295S, P308S, and I310T LPA1 showed decreased maximal responses in inhibition of cAMP formation, Ca(2+) mobilization, and cytoskeletal changes. Y311H LPA1 failed to show LPA-induced cellular responses. However, these LPA1 mutants were internalized in response to LPA exposure. Finally, while WT and F295S LPA1 showed a similar, broad distribution throughout the cell, P308S, I310T, and Y311H LPA1 displayed a restricted cellular distribution and co-localized with the endoplasmic reticulum. These data suggest that the LPA1 mutants perturb LPA signaling in cancer tissues.

  1. Modulation of Nav1.8 by Lysophosphatidic Acid in the Induction of Bone Cancer Pain.

    PubMed

    Pan, Hai-Li; Liu, Ben-Long; Lin, Wei; Zhang, Yu-Qiu

    2016-10-01

    Given that lysophosphatidic acid (LPA) and the tetrodotoxin-resistant sodium channel Nav1.8 are both involved in bone cancer pain, the present study was designed to investigate whether crosstalk between the LPA receptor LPA1 (also known as EDG2) and Nav1.8 in the dorsal root ganglion (DRG) contributes to the induction of bone cancer pain. We showed that the EDG2 antagonist Ki16198 blocked the mechanical allodynia induced by intrathecal LPA in naïve rats and attenuated mechanical allodynia in a rat model of bone cancer. EDG2 and Nav1.8 expression in L4-6 DRGs was upregulated following intrathecal or hindpaw injection of LPA. EDG2 and Nav1.8 expression in ipsilateral L4-6 DRGs increased with the development of bone cancer. Furthermore, we showed that EDG2 co-localized with Nav1.8 and LPA remarkably enhanced Nav1.8 currents in DRG neurons, and this was blocked by either a protein kinase C (PKC) inhibitor or a PKCε inhibitor. Overall, we demonstrated the modulation of Nav1.8 by LPA in DRG neurons, and that this probably underlies the peripheral mechanism by which bone cancer pain is induced.

  2. Lysophosphatidic acid triggers mast cell-driven atherosclerotic plaque destabilization by increasing vascular inflammation.

    PubMed

    Bot, Martine; de Jager, Saskia C A; MacAleese, Luke; Lagraauw, H Maxime; van Berkel, Theo J C; Quax, Paul H A; Kuiper, Johan; Heeren, Ron M A; Biessen, Erik A L; Bot, Ilze

    2013-05-01

    Lysophosphatidic acid (LPA), a bioactive lysophospholipid, accumulates in the atherosclerotic plaque. It has the capacity to activate mast cells, which potentially exacerbates plaque progression. In this study, we thus aimed to investigate whether LPA contributes to plaque destabilization by modulating mast cell function. We here show by an imaging mass spectrometry approach that several LPA species are present in atherosclerotic plaques. Subsequently, we demonstrate that LPA is a potent mast cell activator which, unlike other triggers, favors release of tryptase. Local perivascular administration of LPA to an atherosclerotic carotid artery segment increases the activation status of perivascular mast cells and promotes intraplaque hemorrhage and macrophage recruitment without impacting plaque cell apoptosis. The mast cell stabilizer cromolyn could prevent intraplaque hemorrhage elicited by LPA-mediated mast cell activation. Finally, the involvement of mast cells in these events was further emphasized by the lack of effect of perivascular LPA administration in mast cell deficient animals. We demonstrate that increased accumulation of LPA in plaques induces perivascular mast cell activation and in this way contributes to plaque destabilization in vivo. This study points to local LPA availability as an important factor in atherosclerotic plaque stability.

  3. Coexpressing Escherichia coli Cyclopropane Synthase with Sterculia foetida Lysophosphatidic Acid Acyltransferase Enhances Cyclopropane Fatty Acid Accumulation1[W][OPEN

    PubMed Central

    Yu, Xiao-Hong; Prakash, Richa Rawat; Sweet, Marie; Shanklin, John

    2014-01-01

    Cyclopropane fatty acids (CPAs) are desirable as renewable chemical feedstocks for the production of paints, plastics, and lubricants. Toward our goal of creating a CPA-accumulating crop, we expressed nine higher plant cyclopropane synthase (CPS) enzymes in the seeds of fad2fae1 Arabidopsis (Arabidopsis thaliana) and observed accumulation of less than 1% CPA. Surprisingly, expression of the Escherichia coli CPS gene resulted in the accumulation of up to 9.1% CPA in the seed. Coexpression of a Sterculia foetida lysophosphatidic acid acyltransferase (SfLPAT) increases CPA accumulation up to 35% in individual T1 seeds. However, seeds with more than 9% CPA exhibit wrinkled seed morphology and reduced size and oil accumulation. Seeds with more than 11% CPA exhibit strongly decreased seed germination and establishment, and no seeds with CPA more than 15% germinated. That previous reports suggest that plant CPS prefers the stereospecific numbering (sn)-1 position whereas E. coli CPS acts on sn-2 of phospholipids prompted us to investigate the preferred positions of CPS on phosphatidylcholine (PC) and triacylglycerol. Unexpectedly, in planta, E. coli CPS acts primarily on the sn-1 position of PC; coexpression of SfLPAT results in the incorporation of CPA at the sn-2 position of lysophosphatidic acid. This enables a cycle that enriches CPA at both sn-1 and sn-2 positions of PC and results in increased accumulation of CPA. These data provide proof of principle that CPA can accumulate to high levels in transgenic seeds and sets the stage for the identification of factors that will facilitate the movement of CPA from PC into triacylglycerol to produce viable seeds with additional CPA accumulation. PMID:24204024

  4. Lysophosphatidic acid produced by hen egg white lysophospholipase D induces vascular development on extraembryonic membranes.

    PubMed

    Morishige, Junichi; Uto, Yoshihiro; Hori, Hitoshi; Satouchi, Kiyoshi; Yoshiomoto, Tanihiro; Tokumura, Akira

    2013-03-01

    Lysophosphatidic acid (lysoPtdOH), a lysophospholipid mediator, exerts diverse physiological effects, including angiogenesis, through its specific G-protein-coupled receptors. Previously, we showed that unfertilized hen egg white contains polyunsaturated fatty acid-rich lysoPtdOH and lysophospholipase D (lysoPLD). Here, we examined whether lysoPtdOH was produced by lysoPLD in the presence and absence of a hen fertilized ovum and what the physiological role of lysoPtdOH in hen egg white is. Mass spectrometry showed that fertilized hen egg white contained about 8 μM lysoPtdOH before incubation with an ovum, mainly comprised of 18:1- (12.6 %), 18:2- (37.8 %) and 20:4-molecular species (41.5 %). In an early gestation period, the lysoPtdOH was increased up to 9.6 μM, concomitant with a decrease in the level of polyunsaturated lysophosphatidylcholine (lysoPtdCho). Moreover, lysoPtdOH-degrading activities were found in egg white and the vitelline membrane, showing that these enzymes control lysoPtdOH levels in egg white. In an egg yolk angiogenesis assay, two lysoPtdOH receptor antagonists, Ki16425 and N-palmitoyl serine phosphoric acid (NASP), inhibited blood vessel formation induced by exogenously added 18:1-lysoPtdOH and its precursor lysoPtdCho on the hen yolk sac. Ki16425 and NASP also inhibited blood vessel formation in the chorioallantoic membrane (CAM). Furthermore, the relatively higher levels of LPA₁, LPA₂, LPA₄ and LPA₆ mRNA were present in the yolk sac and CAM. These results suggest that lysoPtdOH produced from lysoPtdCho by the action of lysoPLD in hen egg white is involved in the formation of blood vessel networks through several lysoPtdOH receptors on various extraembryonic membranes, including the yolk sac membrane and CAM.

  5. Structurally divergent lysophosphatidic acid acyltransferases with high selectivity for saturated medium chain fatty acids from Cuphea seeds.

    PubMed

    Kim, Hae Jin; Silva, Jillian E; Iskandarov, Umidjon; Andersson, Mariette; Cahoon, Rebecca E; Mockaitis, Keithanne; Cahoon, Edgar B

    2015-12-01

    Lysophosphatidic acid acyltransferase (LPAT) catalyzes acylation of the sn-2 position on lysophosphatidic acid by an acyl CoA substrate to produce the phosphatidic acid precursor of polar glycerolipids and triacylglycerols (TAGs). In the case of TAGs, this reaction is typically catalyzed by an LPAT2 from microsomal LPAT class A that has high specificity for C18 fatty acids containing Δ9 unsaturation. Because of this specificity, the occurrence of saturated fatty acids in the TAG sn-2 position is infrequent in seed oils. To identify LPATs with variant substrate specificities, deep transcriptomic mining was performed on seeds of two Cuphea species producing TAGs that are highly enriched in saturated C8 and C10 fatty acids. From these analyses, cDNAs for seven previously unreported LPATs were identified, including cDNAs from Cuphea viscosissima (CvLPAT2) and Cuphea avigera var. pulcherrima (CpuLPAT2a) encoding microsomal, seed-specific class A LPAT2s and a cDNA from C. avigera var. pulcherrima (CpuLPATB) encoding a microsomal, seed-specific LPAT from the bacterial-type class B. The activities of these enzymes were characterized in Camelina sativa by seed-specific co-expression with cDNAs for various Cuphea FatB acyl-acyl carrier protein thioesterases (FatB) that produce a variety of saturated medium-chain fatty acids. CvLPAT2 and CpuLPAT2a expression resulted in accumulation of 10:0 fatty acids in the Camelina sativa TAG sn-2 position, indicating a 10:0 CoA specificity that has not been previously described for plant LPATs. CpuLPATB expression generated TAGs with 14:0 at the sn-2 position, but not 10:0. Identification of these LPATs provides tools for understanding the structural basis of LPAT substrate specificity and for generating altered oil functionalities. © 2015 The Authors The Plant Journal © 2015 John Wiley & Sons Ltd.

  6. Lysophosphatidic acid rescues bone mesenchymal stem cells from hydrogen peroxide-induced apoptosis.

    PubMed

    Wang, Xian-Yun; Fan, Xue-Song; Cai, Lin; Liu, Si; Cong, Xiang-Feng; Chen, Xi

    2015-03-01

    The increase of reactive oxygen species in infracted heart significantly reduces the survival of donor mesenchymal stem cells, thereby attenuating the therapeutic efficacy for myocardial infarction. In our previous study, we demonstrated that lysophosphatidic acid (LPA) protects bone marrow-derived mesenchymal stem cells (BMSCs) against hypoxia and serum deprivation-induced apoptosis. However, whether LPA protects BMSCs from H2O2-induced apoptosis was not examined. In this study, we report that H2O2 induces rat BMSC apoptosis whereas LPA pre-treatment effectively protects BMSCs from H2O2-induced apoptosis. LPA protection of BMSC from the induced apoptosis is mediated mostly through LPA3 receptor. Furthermore, we found that membrane G protein Gi2 and Gi3 are involved in LPA-elicited anti-apoptotic effects through activation of ERK1/2- and PI3 K-pathways. Additionally, H2O2 increases levels of type II of light chain 3B (LC3B II), an autophagy marker, and H2O2-induced autophagy thus protected BMSCs from apoptosis. LPA further increases the expression of LC3B II in the presence of H2O2. In contrast, autophagy flux inhibitor bafilomycin A1 has no effect on LPA's protection of BMSC from H2O2-induced apoptosis. Taken together, our data suggest that LPA rescues H2O2-induced apoptosis mainly by interacting with Gi-coupled LPA3, resulting activation of the ERK1/2- and PI3 K/AKT-pathways and inhibition caspase-3 cleavage, and LPA protection of BMSCs against the apoptosis is independent of it induced autophagy.

  7. Lysophosphatidic Acid Promotes Epithelial to Mesenchymal Transition in Ovarian Cancer Cells by Repressing SIRT1.

    PubMed

    Ray, Upasana; Roy, Sib Sankar; Chowdhury, Shreya Roy

    2017-01-01

    Epithelial-to-mesenchymal transition (EMT) plays an essential role in the transition from early to invasive phenotype, however the underlying mechanisms still remain elusive. Herein, we propose a mechanism through which the class-III deacetylase SIRT1 regulates EMT in ovarian cancer (OC) cells. Expression analysis was performed using Q-PCR, western blot, immunofluorescence and fluorescence-IHC study. Matrigel invasion assay was used for the invasion study. Morphological alterations were observed by phalloidin-staining. Co-immunoprecipitation study was performed to analyze protein-protein interaction. Overexpression of SIRT1-WT as well as Resveratrol-mediated SIRT1 activation antagonized the invasion of OC cells by suppressing EMT. SIRT1 deacetylates HIF1α, to inactivate its transcriptional activity. To further validate HIF1α inactivation, its target gene, i.e. ZEB1, an EMT-inducing factor was found to attenuate upon SIRT1 activation. To uncover the regulatory factor governing SIRT1 expression, lysophosphatidic acid (LPA), a highly enriched oncolipid in ascites/serum of OC patients, was found to down-regulate SIRT1 expression. Importantly, LPA was found to induce the mesenchymal switch in OC cells through suppression of SIRT1. Decreased level of SIRT1 was further validated in ovarian tissue samples of OC patients. We have identified a mechanism that relates SIRT1 down-regulation to LPA-induced EMT in OC cells and may open new arenas on developing novel anti-cancer therapeutics. © 2017 The Author(s)Published by S. Karger AG, Basel.

  8. Pro-fibrotic activity of lysophosphatidic acid in adipose tissue: in vivo and in vitro evidence.

    PubMed

    Rancoule, Chloé; Viaud, Manon; Gres, Sandra; Viguerie, Nathalie; Decaunes, Pauline; Bouloumié, Anne; Langin, Dominique; Bascands, Jean-Loup; Valet, Philippe; Saulnier-Blache, Jean Sébastien

    2014-01-01

    Lysophosphatidic acid (LPA) is a pro-fibrotic mediator acting via specific receptors (LPARs) and is synthesized by autotaxin, that increases with obesity. We tested whether LPA could play a role in adipose tissue (AT)-fibrosis associated with obesity. Fibrosis [type I, III, and IV collagens (COL), fibronectin (FN), TGFβ, CTGF and αSMA] and inflammation (MCP1 and F4/80) markers were quantified: (i) in vivo in inguinal (IAT) and perigonadic (PGAT) AT from obese-diabetic db/db mice treated with the LPAR antagonist Ki16425 (5mg/kg/day ip for 7 weeks); and (ii) in vitro in human AT explants in primary culture for 72h in the presence of oleoyl-LPA (10μM) and/or Ki16425 (10μM) and/or the HIF-1α inhibitor YC-1 (100μM). Treatment of db/db mice with Ki16425 reduced Col I and IV mRNAs in IAT and PGAT while Col III mRNAs were only reduced in IAT. This was associated with reduction of COL protein staining in both IAT and PGAT. AT explants showed a spontaneous and time-dependent increase in ATX expression and production of LPA in the culture medium, along with increased levels of Col I and III, TGFβ and αSMA mRNAs and of COL protein staining. In vitro fibrosis was blocked by Ki16425 and was further amplified by oleoyl-LPA. LPA-dependent in vitro fibrosis was blocked by co-treatment with YC1. Our results show that endogenous and exogenous LPA exert a pro-fibrotic activity in AT in vivo and in vitro. This activity could be mediated by an LPA1R-dependent pathway and could involve HIF-1α. © 2013.

  9. Involvement of autotaxin/lysophosphatidic acid signaling in obesity and impaired glucose homeostasis.

    PubMed

    Rancoule, Chloé; Dusaulcy, Rodolphe; Tréguer, Karine; Grès, Sandra; Attané, Camille; Saulnier-Blache, Jean Sébastien

    2014-01-01

    Autotaxin (ATX) is a secreted lysophospholipase D involved in synthesis of lysophosphatidic acid (LPA), a phospholipid growth factor acting via specific receptors (LPA1R to LPA6R) and involved in several pathologies including obesity. ATX is secreted by adipocytes and contributes to circulating LPA. ATX expression is up-regulated in obese patients and mice in relationship with insulin resistance and impaired glucose tolerance. LPA1R is the most abundant subtype in adipose tissue. Its expression is higher in non-adipocyte cells than in adipocytes and is not altered in obesity. ATX increases and LPA1R decreases while preadipocytes differentiate into adipocytes (adipogenesis). LPA inhibits adipogenesis through down-regulation of the pro-adipogenic transcription factor PPARγ2. Adipocyte-specific knockout (FATX-KO) mice or mice treated with the LPAR antagonist Ki16425 gain more weight and accumulate more adipose tissue than wild type or control mice fed a high fat diet (HFD). These observations suggest that LPA (via LPA1R) exerts a tonic inhibitory effect on adipose tissue expansion that could, at least in part, result from the anti-adipogenic activity of LPA. A possible negative impact of LPA on insulin-sensitivity might also be considered. Despite being more sensitive to nutritional obesity, FATX-KO and Ki16425-treated mice fed a HFD show improved glucose tolerance when compared to wild type mice. Moreover, exogenously injected LPA acutely impairs glucose tolerance and insulin secretion. These observations show that LPA exerts a tonic deleterious impact on glucose homeostasis. In conclusion, ATX and LPA1R represent potential interesting pharmacological targets for the treatment of obesity-associated metabolic diseases. Copyright © 2013 Elsevier Masson SAS. All rights reserved.

  10. Lysophosphatidic acid induces chemotaxis in MC3T3-E1 osteoblastic cells.

    PubMed

    Masiello, Lisa M; Fotos, Joseph S; Galileo, Deni S; Karin, Norman J

    2006-07-01

    Lysophosphatidic acid (LPA) is a bioactive lipid that has pleiotropic effects on a variety of cell types and enhances the migration of endothelial and cancer cells, but it is not known if this lipid can alter osteoblast motility. We performed transwell migration assays using MC3T3-E1 osteoblastic cells and found LPA to be a potent chemotactic agent. Quantitative time-lapse video analysis of osteoblast migration after wounds were introduced into cell monolayers indicated that LPA stimulated both migration velocity and the average migration distance per cell. LPA also elicited substantial changes in cell shape and actin cytoskeletal structure; lipid-treated cells contained fewer stress fibers and displayed long membrane processes that were enriched in F-actin. Quantitative RT-PCR analysis showed that MC3T3-E1 cells express all four known LPA-specific G-protein-coupled receptors (LPA1-LPA4) with a relative mRNA abundance of LPA1>LPA4>LPA2>LPA3. LPA-induced changes in osteoblast motility and morphology were antagonized by both pertussis toxin and Ki16425, a subtype-specific blocker of LPA1 and LPA3 receptor function. Cell migration in many cell types is linked to changes in intracellular Ca2+. Ki16425 also inhibited LPA-induced Ca2+ signaling in a dose-dependent manner, suggesting a link between LPA-induced Ca2+ transients and osteoblast chemotaxis. Our data show that LPA stimulates MC3T3-E1 osteoblast motility via a mechanism that is linked primarily to the G-protein-coupled receptor LPA1.

  11. Lysophosphatidic Acid Up-Regulates Hexokinase II and Glycolysis to Promote Proliferation of Ovarian Cancer Cells.

    PubMed

    Mukherjee, Abir; Ma, Yibao; Yuan, Fang; Gong, Yongling; Fang, Zhenyu; Mohamed, Esraa M; Berrios, Erika; Shao, Huanjie; Fang, Xianjun

    2015-09-01

    Lysophosphatidic acid (LPA), a blood-borne lipid mediator, is present in elevated concentrations in ascites of ovarian cancer patients and other malignant effusions. LPA is a potent mitogen in cancer cells. The mechanism linking LPA signal to cancer cell proliferation is not well understood. Little is known about whether LPA affects glucose metabolism to accommodate rapid proliferation of cancer cells. Here we describe that in ovarian cancer cells, LPA enhances glycolytic rate and lactate efflux. A real time PCR-based miniarray showed that hexokinase II (HK2) was the most dramatically induced glycolytic gene to promote glycolysis in LPA-treated cells. Analysis of the human HK2 gene promoter identified the sterol regulatory element-binding protein as the primary mediator of LPA-induced HK2 transcription. The effects of LPA on HK2 and glycolysis rely on LPA2, an LPA receptor subtype overexpressed in ovarian cancer and many other malignancies. We further examined the general role of growth factor-induced glycolysis in cell proliferation. Like LPA, epidermal growth factor (EGF) elicited robust glycolytic and proliferative responses in ovarian cancer cells. Insulin-like growth factor 1 (IGF-1) and insulin, however, potently stimulated cell proliferation but only modestly induced glycolysis. Consistent with their differential effects on glycolysis, LPA and EGF-dependent cell proliferation was highly sensitive to glycolytic inhibition while the growth-promoting effect of IGF-1 or insulin was more resistant. These results indicate that LPA- and EGF-induced cell proliferation selectively involves up-regulation of HK2 and glycolytic metabolism. The work is the first to implicate LPA signaling in promotion of glucose metabolism in cancer cells. Copyright © 2015 The Authors. Published by Elsevier Inc. All rights reserved.

  12. Lysophosphatidic acid receptors (LPARs): Potential targets for the treatment of neuropathic pain.

    PubMed

    Velasco, María; O'Sullivan, Catherine; Sheridan, Graham K

    2017-02-01

    Neuropathic pain can arise from lesions to peripheral or central nerve fibres leading to spontaneous action potential generation and a lowering of the nociceptive threshold. Clinically, neuropathic pain can manifest in many chronic disease states such as cancer, diabetes or multiple sclerosis (MS). The bioactive lipid, lysophosphatidic acid (LPA), via activation of its receptors (LPARs), is thought to play a central role in both triggering and maintaining neuropathic pain. In particular, following an acute nerve injury, the excitatory neurotransmitters glutamate and substance P are released from primary afferent neurons leading to upregulated synthesis of lysophosphatidylcholine (LPC), the precursor for LPA production. LPC is converted to LPA by autotaxin (ATX), which can then activate macrophages/microglia and modulate neuronal functioning. A ubiquitous feature of animal models of neuropathic pain is demyelination of damaged nerves. It is thought that LPA contributes to demyelination through several different mechanisms. Firstly, high levels of LPA are produced following macrophage/microglial activation that triggers a self-sustaining feed-forward loop of de novo LPA synthesis. Secondly, macrophage/microglial activation contributes to inflammation-mediated demyelination of axons, thus initiating neuropathic pain. Therefore, targeting LPA production and/or the family of LPA-activated G protein-coupled receptors (GPCRs) may prove to be fruitful clinical approaches to treating demyelination and the accompanying neuropathic pain. This review discusses our current understanding of the role of LPA/LPAR signalling in the initiation of neuropathic pain and suggests potential targeted strategies for its treatment. This article is part of the Special Issue entitled 'Lipid Sensing G Protein-Coupled Receptors in the CNS'. Copyright © 2016 Elsevier Ltd. All rights reserved.

  13. Synaptic enhancement induced by gintonin via lysophosphatidic acid receptor activation in central synapses.

    PubMed

    Park, Hoyong; Kim, Sungmin; Rhee, Jeehae; Kim, Hyeon-Joong; Han, Jung-Soo; Nah, Seung-Yeol; Chung, ChiHye

    2015-03-01

    Lysophosphatidic acid (LPA) is one of the well-characterized, ubiquitous phospholipid molecules. LPA exerts its effect by activating G protein-coupled receptors known as LPA receptors (LPARs). So far, LPAR signaling has been critically implicated during early development stages, including the regulation of synapse formation and the morphology of cortical and hippocampal neurons. In adult brains, LPARs seem to participate in cognitive as well as emotional learning and memory. Recent studies using LPAR1-deficient mice reported impaired performances in a number of behavioral tasks, including the hippocampus-dependent spatial memory and fear conditioning tests. Nevertheless, the effect of LPAR activation in the synaptic transmission of central synapses after the completion of embryonic development has not been investigated. In this study, we took advantage of a novel extracellular agonist for LPARs called gintonin to activate LPARs in adult brain systems. Gintonin, a recently identified active ingredient in ginseng, has been shown to activate LPARs and mobilize Ca(2+) in an artificial cell system. We found that the activation of LPARs by application of gintonin acutely enhanced both excitatory and inhibitory transmission in central synapses, albeit through tentatively distinct mechanisms. Gintonin-mediated LPAR activation primarily resulted in synaptic enhancement and an increase in neuronal excitability in a phospholipase C-dependent manner. Our findings suggest that LPARs are able to directly potentiate synaptic transmission in central synapses when stimulated exogenously. Therefore, LPARs could serve as a useful target to modulate synaptic activity under pathological conditions, including neurodegenerative diseases. Copyright © 2015 the American Physiological Society.

  14. Loss of lysophosphatidic acid receptor-3 enhances cell migration in rat lung tumor cells

    SciTech Connect

    Hayashi, Mai; Okabe, Kyoko; Yamawaki, Yasuna; Teranishi, Miki; Honoki, Kanya; Mori, Toshio; Fukushima, Nobuyuki; Tsujiuchi, Toshifumi

    2011-02-18

    Research highlights: {yields} Loss of the Lpar3 expression due to aberrant DNA methylation occurred in rat lung tumor cells. {yields} The Lpar3 inhibited cell migration of rat lung tumor cells. {yields} The Lpar3 may act as a negative regulator of rat lung tumor cells. -- Abstract: Lysophosphatidic acid (LPA) indicates several biological effects, such as cell proliferation, differentiation and migration. LPA interacts with G protein-coupled transmembrane LPA receptors. In our previous report, we detected that loss of the LPA receptor-1 (Lpar1) expression is due to its aberrant DNA methylation in rat tumor cell lines. In this study, to assess an involvement of the other LPA receptor, Lpar3, in the pathogenesis of rat lung tumor cells, we measured the expression levels of the Lpar3 gene and its DNA methylation status by reverse transcription (RT)-polymerase chain reaction (PCR) and bisulfite sequencing analyses, respectively. RLCNR lung adenocarcinoma cells showed reduced expression of the Lpar3, compared with normal lung tissues. In the 5' upstream region of the Lpar3, normal lung tissues were unmethylated. By contrast, RLCNR cells were highly methylated, correlating with reduced expressions of the Lpar3. Based on these results, we generated the Lpar3-expressing RLCNR-a3 cells and measured the cell migration ability. Interestingly, the cell migration of RLCNR-a3 cells was significantly lower than that of RLCNR cells. This study suggests that loss of the Lpar3 due to aberrant DNA methylation may be involved in the progression of rat lung tumor cells.

  15. Possible role of lysophosphatidic acid in rat model of hypoxic pulmonary vascular remodeling

    PubMed Central

    2014-01-01

    Abstract Pulmonary hypertension is characterized by cellular and structural changes in the vascular wall of pulmonary arteries. We hypothesized that lysophosphatidic acid (LPA), a bioactive lipid, is implicated in this vascular remodeling in a rat model of hypoxic pulmonary hypertension. Exposure of Wistar rats to 10% O2 for 3 weeks induced an increase in the mean serum levels of LPA, to 40.9 (log-detransformed standard deviations: 23.4–71.7) μM versus 21.6 (11.0–42.3) μM in a matched control animal group (P = 0.037). We also observed perivascular LPA immunohistochemical staining in lungs of hypoxic rats colocalized with the secreted lysophospholipase D autotaxin (ATX). Moreover, ATX colocalized with mast cell tryptase, suggesting implication of these cells in perivascular LPA production. Hypoxic rat lungs expressed more ATX transcripts (2.4-fold) and more transcripts of proteins implicated in cell migration: β2 integrin (1.74-fold), intracellular adhesion molecule 1 (ICAM-1; 1.84-fold), and αM integrin (2.70-fold). Serum from the hypoxic group of animals had significantly higher chemoattractant properties toward rat primary lung fibroblasts, and this increase in cell migration could be prevented by the LPA receptor 1 and 3 antagonists. LPA also increased adhesive properties of human pulmonary artery endothelial cells as well as those of human peripheral blood mononuclear cells, via the activation of LPA receptor 1 or 3 followed by the stimulation of gene expression of ICAM-1, β-1, E-selectin, and vascular cell adhesion molecule integrins. In conclusion, chronic hypoxia increases circulating and tissue levels of LPA, which might induce fibroblast migration and recruitment of mononuclear cells in pulmonary vasculature, both of which contribute to pulmonary vascular remodeling. PMID:25621161

  16. Binding of Autotaxin to Integrins Localizes Lysophosphatidic Acid Production to Platelets and Mammalian Cells*

    PubMed Central

    Fulkerson, Zachary; Wu, Tao; Sunkara, Manjula; Kooi, Craig Vander; Morris, Andrew J.; Smyth, Susan S.

    2011-01-01

    Autotaxin (ATX) is a secreted lysophospholipase D that generates the bioactive lipid mediator lysophosphatidic acid (LPA). We and others have reported that ATX binds to integrins, but the function of ATX-integrin interactions is unknown. The recently reported crystal structure of ATX suggests a role for the solvent-exposed surface of the N-terminal tandem somatomedin B-like domains in binding to platelet integrin αIIbβ3. The opposite face of the somatomedin B-like domain interacts with the catalytic phosphodiesterase (PDE) domain to form a hydrophobic channel through which lysophospholipid substrates enter and leave the active site. Based on this structure, we hypothesize that integrin-bound ATX can access cell surface substrates and deliver LPA to cell surface receptors. To test this hypothesis, we investigated the integrin selectivity and signaling pathways that promote ATX binding to platelets. We report that both platelet β1 and β3 integrins interact in an activation-dependent manner with ATX via the SMB2 domain. ATX increases thrombin-stimulated LPA production by washed platelets ∼10-fold. When incubated under conditions to promote integrin activation, ATX generates LPA from CHO cells primed with bee venom phospholipase A2, and ATX-mediated LPA production is enhanced more than 2-fold by CHO cell overexpression of integrin β3. The effects of ATX on platelet and cell-associated LPA production, but not hydrolysis of small molecule or detergent-solubilized substrates, are attenuated by point mutations in the SMB2 that impair integrin binding. Integrin binding therefore localizes ATX activity to the cell surface, providing a mechanism to generate LPA in the vicinity of its receptors. PMID:21832043

  17. GPR87 mediates lysophosphatidic acid-induced colony dispersal in A431 cells.

    PubMed

    Ochiai, Shoichi; Furuta, Daisuke; Sugita, Kazuya; Taniura, Hideo; Fujita, Norihisa

    2013-09-05

    We have previously reported that an orphan G protein-coupled receptor GPR87 was activated by lysophosphatidic acid (LPA) and that it induced an increase in the intracellular Ca(2+) levels in the CHO cells genetically engineered to express GPR87-Gα16 fusion protein. Because the Ca(2+) response was blocked by the LPA receptor antagonist Ki16425, GPR87 was suggested to be a putative LPA receptor. However, further studies are required to confirm whether GPR87 is an LPA receptor. A previous study showed that colonies of A431 cells treated with LPA showed rapid and synchronized dissociation. Because A431 cells have been shown to express GPR87, we used these cells to examine whether GPR87 acted as an LPA receptor. When A431 cells were treated with gpr87-specific siRNA, the expression of GPR87 was decreased and LPA-induced colony dispersal was significantly reduced. Treatment of the cells with lpa1 siRNA had an additive effect in decrease in the colony dispersal. Studies on the LPA-mediated signaling pathway in A431 cells indicated that transactivation of the epidermal growth factor receptor (EGFR) by LPA led to cell scattering. PD153035, an inhibitor of tyrosine-kinase of EGFR, and BB94, an inhibitor of metalloprotease which produces a ligand for EGFR, significantly prevented the LPA-induced scattering of A431 cells pretreated with lpa1 or gpr87-siRNA. These results strongly suggested that GPR87 acts as an LPA receptor and induces colony dispersal via the transactivation of EGFR in A431 cells. © 2013 Elsevier B.V. All rights reserved.

  18. Gintonin enhances performance of mice in rotarod test: Involvement of lysophosphatidic acid receptors and catecholamine release.

    PubMed

    Lee, Byung-Hwan; Kim, Jisu; Lee, Ra Mi; Choi, Sun-Hye; Kim, Hyeon-Joong; Hwang, Sung-Hee; Lee, Myung Koo; Bae, Chun-Sik; Kim, Hyoung-Chun; Rhim, Hyewon; Lim, Kiwon; Nah, Seung-Yeol

    2016-01-26

    Ginseng has a long history of use as a tonic for restoration of vigor. One example of ginseng-derived tonic effect is that it can improve physical stamina under conditions of stress. However, the active ingredient and the underlying molecular mechanism responsible for the ergogenic effect are unknown. Recent studies show that ginseng contains a novel ingredient, gintonin, which consists of a unique class of herbal-medicine lysophosphatidic acids (LPAs). Gintonin activates G protein-coupled LPA receptors to produce a transient [Ca(2+)]i signal, which is coupled to diverse intra- and inter-cellular signal transduction pathways that stimulate hormone or neurotransmitter release. However, relatively little is known about how gintonin-mediated cellular modulation is linked to physical endurance. In the present study, systemic administration of gintonin, but not ginsenosides, in fasted mice increased blood glucose concentrations in a dose-dependent manner. Gintonin treatment elevated blood glucose to a maximum level after 30min. This elevation in blood glucose level could be abrogated by the LPA1/3 receptor antagonist, Ki16425, or the β-adrenergic receptor antagonist, propranolol. Furthermore, gintonin-dependent enhanced performance of fasted mice in rotarod test was likewise abrogated by Ki16425. Gintonin also elevated plasma epinephrine and norepinephrine concentrations. The present study shows that gintonin mediates catecholamine release through activation of the LPA receptor and that activation of the β-adrenergic receptor is coupled to liver glycogenolysis, thereby increasing the supply of glucose and enhancing performance in the rotarod test. Thus, gintonin acts via the LPA-catecholamine-glycogenolysis axis, representing a candidate mechanism that can explain how ginseng treatment enhances physical stamina. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

  19. Calcium-dependent generation of N-acylethanolamines and lysophosphatidic acids by glycerophosphodiesterase GDE7.

    PubMed

    Rahman, Iffat Ara Sonia; Tsuboi, Kazuhito; Hussain, Zahir; Yamashita, Ryouhei; Okamoto, Yoko; Uyama, Toru; Yamazaki, Naoshi; Tanaka, Tamotsu; Tokumura, Akira; Ueda, Natsuo

    2016-12-01

    N-Acylethanolamines form a class of lipid mediators and include an endocannabinoid arachidonoylethanolamide (anandamide), analgesic and anti-inflammatory palmitoylethanolamide, and appetite-suppressing oleoylethanolamide. In animal tissues, N-acylethanolamines are synthesized from N-acylated ethanolamine phospholipids directly by N-acylphosphatidylethanolamine-hydrolyzing phospholipase D or through multi-step pathways via N-acylethanolamine lysophospholipids. We previously reported that glycerophosphodiesterase (GDE) 4, a member of the GDE family, has lysophospholipase D (lysoPLD) activity hydrolyzing N-acylethanolamine lysophospholipids to N-acylethanolamines. Recently, GDE7 was shown to have lysoPLD activity toward lysophosphatidylcholine to produce lysophosphatidic acid (LPA). Here, we examined the reactivity of GDE7 with N-acylethanolamine lysophospholipids as well as the requirement of divalent cations for its catalytic activity. When overexpressed in HEK293 cells, recombinant GDE7 proteins of human and mouse showed lysoPLD activity toward N-palmitoyl, N-oleoyl, and N-arachidonoyl-lysophosphatidylethanolamines and N-palmitoyl-lysoplasmenylethanolamine to generate their corresponding N-acylethanolamines and LPAs. However, GDE7 hardly hydrolyzed glycerophospho-N-palmitoylethanolamine. Overexpression of GDE7 in HEK293 cells increased endogenous levels of N-acylethanolamines and LPAs. Interestingly, GDE7 was stimulated by micromolar concentrations of Ca(2+) but not by millimolar concentrations of Mg(2+), while GDE4 was stimulated by Mg(2+) but was insensitive to Ca(2+). GDE7 was widely distributed in various tissues of humans and mice with the highest levels in their kidney tissues. These results suggested that GDE7 is a novel Ca(2+)-dependent lysoPLD, which is involved in the generation of both N-acylethanolamines and LPAs. Copyright © 2016 Elsevier B.V. All rights reserved.

  20. Lysophosphatidic acid accelerates lung fibrosis by inducing differentiation of mesenchymal stem cells into myofibroblasts.

    PubMed

    Tang, Na; Zhao, Yanxia; Feng, Ruopeng; Liu, Yinan; Wang, Shuling; Wei, Wanguo; Ding, Qiang; An, Michael Songzhu; Wen, Jinhua; Li, Lingsong

    2014-01-01

    Lung fibrosis is characterized by vascular leakage and myofibroblast recruitment, and both phenomena are mediated by lysophosphatidic acid (LPA) via its type-1 receptor (LPA1). Following lung damage, the accumulated myofibroblasts activate and secrete excessive extracellular matrix (ECM), and form fibrotic foci. Studies have shown that bone marrow-derived cells are an important source of myofibroblasts in the fibrotic organ. However, the type of cells in the bone marrow contributing predominantly to the myofibroblasts and the involvement of LPA-LPA1 signalling in this is yet unclear. Using a bleomycin-induced mouse lung-fibrosis model with an enhanced green fluorescent protein (EGFP) transgenic mouse bone marrow replacement, we first demonstrated that bone marrow derived-mesenchymal stem cells (BMSCs) migrated markedly to the bleomycin-injured lung. The migrated BMSC contributed significantly to α-smooth muscle actin (α-SMA)-positive myofibroblasts. By transplantation of GFP-labelled human BMSC (hBMSC) or EGFP transgenic mouse BMSC (mBMSC), we further showed that BMSC might be involved in lung fibrosis in severe combined immune deficiency (SCID)/Beige mice induced by bleomycin. In addition, using quantitative-RT-PCR, western blot, Sircol collagen assay and migration assay, we determined the underlying mechanism was LPA-induced BMSC differentiation into myofibroblast and the secretion of ECM via LPA1. By employing a novel LPA1 antagonist, Antalpa1, we then showed that Antalpa1 could attenuate lung fibrosis by inhibiting both BMSC differentiation into myofibroblast and the secretion of ECM. Collectively, the above findings not only further validate LPA1 as a drug target in the treatment of pulmonary fibrosis but also elucidate a novel pathway in which BMSCs contribute to the pathologic process. © 2013 The Authors. Journal of Cellular and Molecular Medicine published by John Wiley & Sons Ltd and Foundation for Cellular and Molecular Medicine.

  1. Conventional protein kinase C isoforms mediate phorbol ester-induced lysophosphatidic acid LPA1 receptor phosphorylation.

    PubMed

    Hernández-Méndez, Aurelio; Alcántara-Hernández, Rocío; Acosta-Cervantes, Germán C; Martínez-Ortiz, Javier; Avendaño-Vázquez, S Eréndira; García-Sáinz, J Adolfo

    2014-01-15

    Using C9 cells stably expressing LPA1 receptors fused to the enhanced green fluorescent protein, it was observed that activation of protein kinase C induced a rapid and strong increase in the phosphorylation state of these receptors. Overnight incubation with phorbol esters markedly decreased the amount of conventional (α, βI, βII and γ) and novel (δ) but not atypical (ζ) immunodetected PKC isoforms, this treatment blocks the action of protein kinase on receptor function and phosphorylation. Bis-indolylmaleimide I a general, non-subtype selective protein kinase C inhibitor, and Gö 6976, selective for the isoforms α and β, were also able to block LPA1 receptor desensitization and phosphorylation; hispidin, isoform β-selective blocker partially avoided receptor desensitization. Expression of dominant-negative protein kinase C α or β II mutants and knocking down the expression of these kinase isozymes markedly decreased phorbol ester-induced LPA1 receptor phosphorylation without avoiding receptor desensitization. This effect was blocked by bis-indolyl-maleimide and Gö 6976, suggesting that these genetic interventions were not completely effective. It was also observed that protein kinase C α and β II isozymes co-immunoprecipitate with LPA1 receptors and that such an association was further increased by cell treatments with phorbol esters or lysophosphatidic acid. Our data suggest that conventional protein kinase C α and β isozymes modulate LPA1 receptor phosphorylation state. Receptor desensitization appears to be a more complex process that might involve additional elements. Copyright © 2013 Elsevier B.V. All rights reserved.

  2. Lysophosphatidic acid directly induces macrophage-derived foam cell formation by blocking the expression of SRBI.

    PubMed

    Chen, Linmu; Zhang, Jun; Deng, Xiao; Liu, Yan; Yang, Xi; Wu, Qiong; Yu, Chao

    2017-09-23

    The leading cause of morbidity and mortality is the result of cardiovascular disease, mainly atherosclerosis. The formation of macrophage foam cells by ingesting ox-LDL and focal retention in the subendothelial space are the hallmarks of the early atherosclerotic lesion. Lysophosphatidic acid (LPA), which is a low-molecular weight lysophospholipid enriched in oxidized LDL, exerts a range of effects on the cardiovascular system. Previous reports show that LPA increases the uptake of ox-LDL to promote the formation of foam cells. However, as the most active component of ox-LDL, there is no report showing whether LPA directly affects foam cell formation. The aim of this study was to investigate the effects of LPA on foam cell formation, as well as to elucidate the underlying mechanism. Oil red O staining and a Cholesterol/cholesteryl ester quantitation assay were used to evaluate foam cell formation in Raw264.7 macrophage cells. We utilized a Western blot and RT-PCR to investigate the relationship between LPA receptors and lipid transport related proteins. We found that LPA promoted foam cell formation, using 200 μM for 24 h. Meanwhile, the expression of the Scavenger receptor BI (SRBI), which promotes the efflux of free cholesterol, was decreased. Furthermore, the LPA1/3 receptor antagonist Ki16425 significantly abolished the LPA effects, indicating that LPA1/3 was involved in the foam cell formation and SRBI expression induced by LPA. Additionally, the LPA-induced foam cell formation was blocked with an AKT inhibitor. Our results suggest that LPA-enhanced foam cell formation is mediated by LPA1/3 -AKT activation and subsequent SRBI expression. Copyright © 2017. Published by Elsevier Inc.

  3. Lysophosphatidic acid expression in theca cells depends on the type of bovine ovarian follicle.

    PubMed

    Sinderewicz, E; Grycmacher, K; Boruszewska, D; Kowalczyk-Zięba, I; Woclawek-Potocka, I

    2017-02-01

    Lysophosphatidic acid (LPA) exerts various actions on the mammalian reproductive system. In cows, LPA stimulates the synthesis and secretion of luteotropic factors in the ovary, which affects the growth and development of ovarian follicles. The role of LPA in granulosa cells, oocyte and oocyte-cumulus complex (COC) has previously been investigated; but its role in the theca layer, which is an important structural and functional component of the ovarian follicle, is still unclear. The goal of this study was to investigate the expression of LPA in theca cells originating from different bovine ovarian follicle types. Theca cells were separated from healthy, transitional and atretic ovarian follicles, based on intrafollicular estradiol: progesterone ratios. LPA concentration in the follicular fluid (FF) in different follicle types was measured, and expression of the enzymes responsible for LPA synthesis (autotaxin [AX], phospholipase A2 [PLA2]) and receptors for LPA (LPAR1-4) were determined. The obtained results confirmed the follicle-type dependent presence of LPA in the FF of the bovine ovarian follicles. The highest concentration of LPA was detected in follicles classified as healthy and dominant. LPAR1-4, PLA2 and AX expression in theca cells in all of the types of follicles examined were detected at mRNA and protein level. These results suggest that theca cells can be a source of LPA synthesis other than granulosa cells and COCs, as well as the target for its action in the bovine ovarian follicle, with PLA2 and LPAR4 playing major roles in LPA synthesis and action. © 2016 Blackwell Verlag GmbH.

  4. Expressions of lysophosphatidic acid receptors in the development of human ovarian carcinoma

    PubMed Central

    Si, Jinge; Su, Yuanyuan; Wang, Yifeng; Yan, You-Liang; Tang, Ya-Ling

    2015-01-01

    Aim: To investigate the associations between the expressions of three lysophosphatidic acid (LPA) receptors (LPA1-3) and the development of ovarian carcinoma (OC). Method: Ovarian tissue specimens, including normal ovarian epithelium tissues, benign ovarian tumor tissues and OC tissues were collected from patients who underwent surgical resections between March 2012 and December 2014. Immunohistochemical staining was used to detect LPA receptor expressions in ovarian tissues. Reverse transcription-polymerase chain reaction and Western blotting were used to detect mRNA and protein expression of LPA receptors, respectively. Association analysis between LPA receptors protein expression and clinical pathological characteristics was conducted. The value of LPA2 and LPA3 in discriminating OC was confirmed by receiver-operator characteristic (ROC) curves analysis. Results: The positive expression rates of LPA2 and LPA3 in OC group was obviously higher than normal control and benign groups. The LPA2 and LPA3 mRNA and protein levels in OC group were higher than in normal control and benign groups. LPA2 and LPA3 mRNA expression levels were positively correlated with LPA2 and LPA3 protein expression in OC group. ROC curve analysis revealed that LPA2 yield a specificity of 96.3% and a sensitivity of 97.9%, and LPA3 yield a specificity of 98.5% and a sensitivity of 97.9% for the detection of OC. Conclusion: LPA2 and LPA3 were highly expressed in OC tissues, which may be involved in the development of OC. Further, LPA2 and LPA3 had higher sensitivity and specificity in distinguishing the OC from benign ovarian tumors, which could be potential diagnostic indictors in OC. PMID:26770382

  5. Activation of Lysophosphatidic Acid Receptor Type 1 Contributes to Pathophysiology of Spinal Cord Injury.

    PubMed

    Santos-Nogueira, Eva; López-Serrano, Clara; Hernández, Joaquim; Lago, Natalia; Astudillo, Alma M; Balsinde, Jesús; Estivill-Torrús, Guillermo; de Fonseca, Fernando Rodriguez; Chun, Jerold; López-Vales, Rubèn

    2015-07-15

    Lysophosphatidic acid (LPA) is an extracellular lipid mediator involved in many physiological functions that signals through six known G-protein-coupled receptors (LPA1-LPA6). A wide range of LPA effects have been identified in the CNS, including neural progenitor cell physiology, astrocyte and microglia activation, neuronal cell death, axonal retraction, and development of neuropathic pain. However, little is known about the involvement of LPA in CNS pathologies. Herein, we demonstrate for the first time that LPA signaling via LPA1 contributes to secondary damage after spinal cord injury. LPA levels increase in the contused spinal cord parenchyma during the first 14 d. To model this potential contribution of LPA in the spinal cord, we injected LPA into the normal spinal cord, revealing that LPA induces microglia/macrophage activation and demyelination. Use of a selective LPA1 antagonist or mice lacking LPA1 linked receptor-mediated signaling to demyelination, which was in part mediated by microglia. Finally, we demonstrate that selective blockade of LPA1 after spinal cord injury results in reduced demyelination and improvement in locomotor recovery. Overall, these results support LPA-LPA1 signaling as a novel pathway that contributes to secondary damage after spinal cord contusion in mice and suggest that LPA1 antagonism might be useful for the treatment of acute spinal cord injury. This study reveals that LPA signaling via LPA receptor type 1 activation causes demyelination and functional deficits after spinal cord injury. Copyright © 2015 the authors 0270-6474/15/3510224-12$15.00/0.

  6. Lysophosphatidic acid induces anxiety-like behavior via its receptors in mice.

    PubMed

    Yamada, Misa; Tsukagoshi, Mai; Hashimoto, Tomio; Oka, Jun-Ichiro; Saitoh, Akiyoshi; Yamada, Mitsuhiko

    2015-03-01

    Lysophosphatidic acid (LPA) is a potent bioactive lipid mediator with diverse biological properties. We previously found altered expression of the LPA-related genes in rodents after treatment with sertraline, which is widely used to treat anxiety disorders and depression. However, little is known about the behavioral effects of LPA. In the present study, we investigated the behavioral effects of intracerebroventricular injection of LPA in adult mice. LPA did not significantly affect spontaneous locomotor activity, suggesting that LPA does not induce hyperactivity, ataxia, or sedation. We next investigated the emotional effects of LPA via the hole-board test. LPA significantly increased the number of head-dips in a dose- and time-related manner. A significant induction of head-dip counts occurred 15 and 30 min after LPA administration. To clarify the involvement of LPA receptors, we examined the effect of the non-selective LPA1-4 receptor antagonist, 1-bromo-3(S)-hydroxy-4-(palmitoyloxy)butyl-phosphonate (BrP-LPA) co-administered with LPA. BrP-LPA dose-dependently inhibited LPA-induced head-dip counts. We next investigated anxiety-like behavior via the elevated plus-maze test. LPA significantly reduced the percentage of time spent in the open arms and BrP-LPA dose-dependently inhibited this anxiety-like behavior. In conclusion, LPA induced anxiety-like behavior in mice via LPA receptors. Our results suggest that LPA signaling plays an important role in regulating anxiety in mice.

  7. Lysophosphatidic acid induces chemotaxis in MC3T3-E1 osteoblastic cells

    SciTech Connect

    Masiello, Lisa M.; Fotos, Joseph S.; Galileo, Deni S.; Karin, Norm J.

    2006-07-01

    Lysophosphatidic acid (LPA) is a bioactive lipid that has pleiotropic effects on a variety of cell types and enhances the migration of endothelial and cancer cells, but it is not known if this lipid can alter osteoblast motility. We performed transwell migration assays using MC3T3-E1 osteoblastic cells and found LPA to be a potent chemotactic agent. Quantitative time-lapse video analysis of osteoblast migration after wounds were introduced into cell monolayers indicated that LPA stimulated both migration velocity and the average migration distance per cell. LPA also elicited substantial changes in cell shape and actin cytoskeletal structure; lipid-treated cells contained fewer stress fibers and displayed long membrane processes that were enriched in F-actin. Quantitative RT-PCR analysis showed that MC3T3-E1 cells express all four known LPA-specific G protein-coupled receptors (LPA1-LPA4) with a relative mRNA abundance of LPA1 > LPA4 > LPA2 >> LPA3. LPA-induced changes in osteoblast motility and morphology were antagonized by both pertussis toxin and Ki16425, a subtype-specific blocker of LPA1 and LPA3 receptor function. Cell migration in many cell types is linked to changes in intracellular Ca2+. Ki16425 also inhibited LPA-induced Ca2+ signaling in a dose-dependent manner, suggesting a link between LPA-induced Ca2+ transients and osteoblast chemotaxis. Our data show that LPA stimulates MC3T3-E1 osteoblast motility via a mechanism that is linked primarily to the G protein-coupled receptor LPA1.

  8. Lysophosphatidic acid receptor-5 negatively regulates cellular responses in mouse fibroblast 3T3 cells.

    PubMed

    Dong, Yan; Hirane, Miku; Araki, Mutsumi; Fukushima, Nobuyuki; Tsujiuchi, Toshifumi

    2014-04-04

    Lysophosphatidic acid (LPA) signaling via G protein-coupled LPA receptors (LPA1-LPA6) mediates a variety of biological functions, including cell migration. Recently, we have reported that LPA1 inhibited the cell motile activities of mouse fibroblast 3T3 cells. In the present study, to evaluate a role of LPA5 in cellular responses, Lpar5 knockdown (3T3-L5) cells were generated from 3T3 cells. In cell proliferation assays, LPA markedly stimulated the cell proliferation activities of 3T3-L5 cells, compared with control cells. In cell motility assays with Cell Culture Inserts, the cell motile activities of 3T3-L5 cells were significantly higher than those of control cells. The activity levels of matrix metalloproteinases (MMPs) were measured by gelatin zymography. 3T3-L5 cells stimulated the activation of Mmp-2, correlating with the expression levels of Mmp-2 gene. Moreover, to assess the co-effects of LPA1 and LPA5 on cell motile activities, Lpar5 knockdown (3T3a1-L5) cells were also established from Lpar1 over-expressing (3T3a1) cells. 3T3a1-L5 cells increased the cell motile activities of 3T3a1 cells, while the cell motile activities of 3T3a1 cells were significantly lower than those of control cells. These results suggest that LPA5 may act as a negative regulator of cellular responses in mouse fibroblast 3T3 cells, similar to the case for LPA1.

  9. Sphingosine kinase 1 is upregulated with lysophosphatidic acid receptor 2 in human colorectal cancer.

    PubMed

    Shida, Dai; Inoue, Satoru; Yoshida, Yuki; Kodaka, Atsushi; Tsuji, Tsutomu; Tsuiji, Makoto

    2016-02-28

    To examine the expression of SphK1, an oncogenic kinase that produces sphingosine 1-phosphate (S1P), and its correlation with the expression of LPAR2, a major lysophosphatidic acid (LPA) receptor overexpressed in various cancers, in human colorectal cancer. Real-time reverse-transcription polymerase chain reaction was used to measure the mRNA expression of SphK1, LPAR2, and the three major S1P receptors in 27 colorectal cancer samples and corresponding normal tissue samples. We also examined the correlation between the expression of SphK1 and LPAR2. Colorectal cancer tissue in 22 of 27 patients had higher levels of SphK1 mRNA than in normal tissue. In two-thirds of the samples, SphK1 mRNA expression was more than two-fold higher than in normal tissue. Consistent with previous reports, LPAR2 mRNA expression in 20 of 27 colorectal cancer tissue samples was higher compared to normal tissue samples. Expression profiles of all three major S1P receptors, S1PR1, S1PR2, and S1PR3, varied without any trend, with no significant difference in expression between cancer and normal tissues. A highly significant positive correlation was found between SphK1 and LPAR2 expression [Pearson's correlation coefficient (r) = 0.784 and P < 0.01]. The mRNA levels of SphK1 and LPAR2 did not correlate with TNM stage. Our findings suggest that S1P and LPA may play important roles in the development of colorectal cancer via the upregulation of SphK1 and LPAR2, both of which could serve as new therapeutic targets in the treatment of colorectal cancer.

  10. Autotaxin Regulates Maintenance of Ovarian Cancer Stem Cells through Lysophosphatidic Acid-Mediated Autocrine Mechanism.

    PubMed

    Seo, Eun Jin; Kwon, Yang Woo; Jang, Il Ho; Kim, Dae Kyoung; Lee, Soo In; Choi, Eun Jung; Kim, Ki-Hyung; Suh, Dong-Soo; Lee, Jeong Hee; Choi, Kyung Un; Lee, Jae Won; Mok, Hyuck Jun; Kim, Kwang Pyo; Matsumoto, Hirotaka; Aoki, Junken; Kim, Jae Ho

    2016-03-01

    Ovarian cancer shows high mortality due to development of resistance to chemotherapy and relapse. Cancer stem cells (CSCs) have been suggested to be a major contributor in developing drug resistance and relapse in ovarian cancer. In this study, we isolated CSCs through sphere culture of A2780, SKOV3, OVCAR3 epithelial ovarian cancer cells and primary ovarian cancer cells from patients. We identified heat-stable factors secreted from ovarian CSCs stimulated migration and proliferation of CSCs. Mass spectrometry and ELISA analysis revealed that lysophosphatidic acid (LPA) was significantly elevated in CSC culture media compared with non-CSC culture media. Treatment of CSCs with LPA resulted in augmented CSC characteristics such as sphere-forming ability, resistance to anticancer drugs, tumorigenic potential in xenograft transplantation, and high expression of CSC-associated genes, including OCT4, SOX2, and aldehyde dehydrogenase 1. Treatment of CSCs with LPA receptor 1-specific inhibitors or silencing of LPA receptor 1 expression abrogated the LPA-stimulated CSC properties. Autotaxin, an LPA-producing enzyme, is highly secreted from ovarian CSCs, and pharmacological inhibition or knockdown of autotaxin markedly attenuated the LPA-producing, tumorigenic, and drug resistance potentials of CSCs. Clinicopathological analysis showed a significant survival disadvantage of patients with positive staining of autotaxin. In addition, we further identified that AKT1 activity was upregulated in ovarian CSCs through an LPA-dependent mechanism and silencing of AKT1 expression led to suppression of CSC characteristics. These results suggest that autotaxin-LPA-LPA receptor 1-AKT1 signaling axis is critical for maintaining CSC characteristics through an autocrine loop and provide a novel therapeutic target for ovarian CSCs. © 2016 AlphaMed Press.

  11. Ginseng pharmacology: a new paradigm based on gintonin-lysophosphatidic acid receptor interactions

    PubMed Central

    Choi, Sun-Hye; Jung, Seok-Won; Lee, Byung-Hwan; Kim, Hyeon-Joong; Hwang, Sung-Hee; Kim, Ho-Kyoung; Nah, Seung-Yeol

    2015-01-01

    Ginseng, the root of Panax ginseng, is used as a traditional medicine. Despite the long history of the use of ginseng, there is no specific scientific or clinical rationale for ginseng pharmacology besides its application as a general tonic. The ambiguous description of ginseng pharmacology might be due to the absence of a predominant active ingredient that represents ginseng pharmacology. Recent studies show that ginseng abundantly contains lysophosphatidic acids (LPAs), which are phospholipid-derived growth factor with diverse biological functions including those claimed to be exhibited by ginseng. LPAs in ginseng form a complex with ginseng proteins, which can bind and deliver LPA to its cognate receptors with a high affinity. As a first messenger, gintonin produces second messenger Ca2+ via G protein-coupled LPA receptors. Ca2+ is an intracellular mediator of gintonin and initiates a cascade of amplifications for further intercellular communications by activation of Ca2+-dependent kinases, receptors, gliotransmitter, and neurotransmitter release. Ginsenosides, which have been regarded as primary ingredients of ginseng, cannot elicit intracellular [Ca2+]i transients, since they lack specific cell surface receptor. However, ginsenosides exhibit non-specific ion channel and receptor regulations. This is the key characteristic that distinguishes gintonin from ginsenosides. Although the current discourse on ginseng pharmacology is focused on ginsenosides, gintonin can definitely provide a mode of action for ginseng pharmacology that ginsenosides cannot. This review article introduces a novel concept of ginseng ligand-LPA receptor interaction and proposes to establish a paradigm that shifts the focus from ginsenosides to gintonin as a major ingredient representing ginseng pharmacology. PMID:26578955

  12. Lysophosphatidic Acid Pretreatment Attenuates Myocardial Ischemia/Reperfusion Injury in the Immature Hearts of Rats

    PubMed Central

    Chen, Haibo; Liu, Si; Liu, Xuewen; Yang, Jinjing; Wang, Fang; Cong, Xiangfeng; Chen, Xi

    2017-01-01

    The cardioprotection of the immature heart during cardiac surgery remains controversial due to the differences between the adult heart and the newborn heart. Lysophosphatidic acid (LPA) is a small bioactive molecule with diverse functions including cell proliferation and survival via its receptor: LPA1–LPA6. We previously reported that the expressions of LPA1 and LPA3 in rat hearts were much higher in immature hearts and then declined rapidly with age. In this study, we aimed to investigate whether LPA signaling plays a potential protective role in immature hearts which had experienced ischemia/reperfusion (I/R) injury. The results showed that in Langendorff-perfused immature rat hearts (2 weeks), compared to I/R group, LPA pretreatment significantly enhanced the cardiac function, attenuated myocardial infarct size and CK-MB release, decreased myocardial apoptosis and increased the expression of pro-survival signaling molecules. All these effects could be abolished by Ki16425, an antagonist to LPA1 and LPA3. Similarly, LPA pretreatment protected H9C2 from hypoxia-reoxygenation (H/R) induced apoptosis and necrosis in vitro. The mechanisms underlying the anti-apoptosis effects were related to activation of the phosphatidylinositol 3-kinase (PI3K)/protein kinas B (AKT) signaling pathways as well as phosphorylation of the downstream effector of AKT, glycogen synthase kinase 3 beta (GSK3β), through LPA1 and/or LPA3. What's more, we found that LPA preconditioning increased glucose uptake of H9C2 subjected to H/R by the activation of AMP-Activated Protein Kinase (AMPK) but not the translocation of GLUT4. In conclusion, our study indicates that LPA is a potent survival factor for immature hearts against I/R injuries and has the potential therapeutic function as a cardioplegia additive for infantile cardiac surgery. PMID:28377726

  13. Activation of protein kinase C by lysophosphatidic acid: dependence on composition of phospholipid vesicles.

    PubMed Central

    Sando, J J; Chertihin, O I

    1996-01-01

    Lysophosphatidic acid (LPA) has attracted recent attention as a major serum-derived regulator implicated in responses to vascular injury and inflammation, in tumour invasiveness and in neuronal signalling and remodelling. Although the possibility of a specific G-protein-coupled LPA receptor protein has been suggested, characterization of such a receptor is lacking. Since LPA can activate protein kinase C (PKC) pathways in many cells and PKC activators mimic many LPA effects, the possibility of more direct LPA effects on PKC was investigated. Phosphatidylcholine (PC)/phosphatidylserine (PS)/diacylglycerol (DAG) lipid vesicles of defined acyl chain composition were used to activate the enzyme. At total concentrations of saturated PC/PS + DAG vesicles (2-3 mM) that provided maximal PKC activation, 1-10 mol % [18:1]-LPA led to a further approx. 2-fold activation of PKC alpha. At lower lipid concentrations, a greater increase was observed with LPA concentrations up to 16-20 mol %. Higher concentrations of LPA were inhibitory. The LPA activation of PKC was dependent on the presence of DAG, PS and Ca2+. [18:1]-Lysophosphatidylcholine produced similar PKC activation in PC/PS/DAG vesicles. [14:0]-LPA was less effective, and longer-chain saturated lysolipids were ineffective. In unsaturated PC/PS vesicles, very little to no effect of LPA was discernable. These results suggest that physiologically or pathologically relevant concentrations of LPA can contribute to PKC activation depending on the composition of the lipid membrane. We hypothesize that LPA may affect the formation of lipid domains that are recognized by the enzyme. PMID:8713089

  14. Activity of 2-substituted lysophosphatidic acid (LPA) analogs at LPA receptors: discovery of a LPA1/LPA3 receptor antagonist.

    PubMed

    Heise, C E; Santos, W L; Schreihofer, A M; Heasley, B H; Mukhin, Y V; Macdonald, T L; Lynch, K R

    2001-12-01

    The physiological implications of lysophosphatidic acid occupancy of individual receptors are largely unknown because selective agonists/antagonists are unavailable currently. The molecular cloning of three high-affinity lysophosphatidic acid receptors, LPA1, LPA2, and LPA3, provides a platform for developing receptor type-selective ligands. Starting with an N-acyl ethanolamide phosphate LPA analog, we made a series of substitutions at the second carbon to generate compounds with varying spatial, stereochemical, and electronic characteristics. Analysis of this series at each recombinant LPA receptor using a guanosine 5'-O-(3-[35S]thio)triphosphate (GTP[gamma35S]) binding assay revealed sharp differences in activity. Our results suggest that these receptors have one spatially restrictive binding pocket that interacts with the 2-substituted moieties and prefers small hydrophobic groups and hydrogen bonding functionalities. The agonist activity predicted by the GTP[gamma35S] binding assay was reflected in the activity of a subset of compounds in increasing arterial pressure in anesthetized rats. One compound with a bulky hydrophobic group (VPC12249) was a dual LPA1/LPA3 competitive antagonist. Several compounds that had smaller side chains were found to be LPA1-selective agonists.

  15. Reduced rat plasma lysophosphatidylglycerol or lysophosphatidic acid level as a biomarker of aristolochic acid-induced renal and adipose dysfunctions.

    PubMed

    Tsutsumi, Toshihiko; Okamoto, Yoko; Yamakawa, Syougo; Bingjun, Cheng; Ishihara, Akira; Tanaka, Tamotsu; Tokumura, Akira

    2016-07-15

    Food products and diet pills containing aristolochic acid (AA) are responsible for a rapid progression of nephropathy associated with reduced body weight in human beings. In this study, we investigated the relationship of dietary NaCl and lysophospholipid (LPL) plasma levels to body weight gain in AA-treated rats. Male rats receiving a salt-deficient chow, normal salt chow or high salt chow were injected intraperitoneally daily with AA for 15days. Body weight, visceral fat mass, food intake, levels of LPL in plasma and its synthesized enzyme were investigated. Body weight gain, visceral fat mass and daily food intake were smaller in AA-treated rats than those of control rats, regardless of dietary salt concentration. AA treatment decreased plasma levels of major lysophosphatidic acid (LPA) molecular species in rats fed the normal or high-salt chow but not the salt-deficient chow, whereas both the plasma lysophospholipase D activity and kidney mRNA level of autotaxin of AA-treated rats fed chow with defined salt concentrations were lower than those of control rats. Plasma levels of major molecular species of lysophosphatidylglycerol (LPG) in AA-treated rat groups fed chow with defined salt concentrations were lower than those of control rats. Plasma levels of LPG and LPA seem to be relevant to the reduced body weight gain and fat mass due to AA treatment. Copyright © 2016 Elsevier Inc. All rights reserved.

  16. Diagnostic and prognostic significance of lysophosphatidic acid in malignant pleural effusions

    PubMed Central

    Bai, Cui-Qing; Yao, Yan-Wen; Liu, Chun-Hua; Zhang, He; Xu, Xiao-Bing; Zeng, Jun-Li; Liang, Wen-Jun; Yang, Wen

    2014-01-01

    Background Lysophosphatidic acid (LPA) is an important extracellular signal transmitter and intracellular second messenger in body fluids. It can be detected in the ascitic fluid of patients with ovarian cancer. Increasing evidence shows that LPA can stimulate cancer cell proliferation and promote tumor invasion and metastasis. Our study aimed to evaluate the diagnostic value of LPA in differentiating between malignant pleural effusions (MPEs) and benign pleural effusions (BPEs) and to evaluate the association between the level of LPA in MPE and the prognosis of lung cancer patients. Patients and methods The level of LPA in the pleural effusions (PEs) of 123 patients (94 MPE, 29 BPE) with lung cancer was evaluated using an enzyme-linked immunosorbent assay. The performance of LPA was analyzed by standard Receiver operator characteristic curve (ROC) analysis methods, using the area under the curve (AUC) as a measure of accuracy. Overall survival (OS) curves and progression-free survival (PFS) curves were based on the Kaplan-Meier method, and the survival differences between subgroups were analyzed using the log-rank or Breslow test (SPSS software). A multivariate Cox proportional hazards model was used to assess whether LPA independently predicted lung cancer survival. Results The levels of LPA differed significantly between MPE (22.08±8.72 µg/L) and BPE (14.61±5.12 µg/L) (P<0.05). Using a cutoff point of 18.93 µg/L, LPA had a sensitivity of 60% and a specificity of 83% to distinguish MPEs from BPEs with an AUC of 0.769±0.045 (SE) (P=0.000) (95% CI, 0.68-0.857). In the three pathological types of lung cancer patients with MPE, there were no significant associations between LPA levels and the length of PFS and OS (P=0.58 and 0.186, respectively). Interestingly, in the patients with MPE caused by lung adenocarcinoma there were significant associations between the LPA levels and the PFS and OS (P=0.018 and 0.026, respectively). Multivariate analysis showed that

  17. Lysophosphatidic acid receptor-5 negatively regulates cellular responses in mouse fibroblast 3T3 cells

    SciTech Connect

    Dong, Yan; Hirane, Miku; Araki, Mutsumi; Fukushima, Nobuyuki; Tsujiuchi, Toshifumi

    2014-04-04

    Highlights: • LPA{sub 5} inhibits the cell growth and motile activities of 3T3 cells. • LPA{sub 5} suppresses the cell motile activities stimulated by hydrogen peroxide in 3T3 cells. • Enhancement of LPA{sub 5} on the cell motile activities inhibited by LPA{sub 1} in 3T3 cells. • The expression and activation of Mmp-9 were inhibited by LPA{sub 5} in 3T3 cells. • LPA signaling via LPA{sub 5} acts as a negative regulator of cellular responses in 3T3 cells. - Abstract: Lysophosphatidic acid (LPA) signaling via G protein-coupled LPA receptors (LPA{sub 1}–LPA{sub 6}) mediates a variety of biological functions, including cell migration. Recently, we have reported that LPA{sub 1} inhibited the cell motile activities of mouse fibroblast 3T3 cells. In the present study, to evaluate a role of LPA{sub 5} in cellular responses, Lpar5 knockdown (3T3-L5) cells were generated from 3T3 cells. In cell proliferation assays, LPA markedly stimulated the cell proliferation activities of 3T3-L5 cells, compared with control cells. In cell motility assays with Cell Culture Inserts, the cell motile activities of 3T3-L5 cells were significantly higher than those of control cells. The activity levels of matrix metalloproteinases (MMPs) were measured by gelatin zymography. 3T3-L5 cells stimulated the activation of Mmp-2, correlating with the expression levels of Mmp-2 gene. Moreover, to assess the co-effects of LPA{sub 1} and LPA{sub 5} on cell motile activities, Lpar5 knockdown (3T3a1-L5) cells were also established from Lpar1 over-expressing (3T3a1) cells. 3T3a1-L5 cells increased the cell motile activities of 3T3a1 cells, while the cell motile activities of 3T3a1 cells were significantly lower than those of control cells. These results suggest that LPA{sub 5} may act as a negative regulator of cellular responses in mouse fibroblast 3T3 cells, similar to the case for LPA{sub 1}.

  18. Golgi membrane fission requires the CtBP1-S/BARS-induced activation of lysophosphatidic acid acyltransferase δ

    PubMed Central

    Pagliuso, Alessandro; Valente, Carmen; Giordano, Lucia Laura; Filograna, Angela; Li, Guiling; Circolo, Diego; Turacchio, Gabriele; Marzullo, Vincenzo Manuel; Mandrich, Luigi; Zhukovsky, Mikhail A.; Formiggini, Fabio; Polishchuk, Roman S.; Corda, Daniela; Luini, Alberto

    2016-01-01

    Membrane fission is an essential cellular process by which continuous membranes split into separate parts. We have previously identified CtBP1-S/BARS (BARS) as a key component of a protein complex that is required for fission of several endomembranes, including basolateral post-Golgi transport carriers. Assembly of this complex occurs at the Golgi apparatus, where BARS binds to the phosphoinositide kinase PI4KIIIβ through a 14-3-3γ dimer, as well as to ARF and the PKD and PAK kinases. We now report that, when incorporated into this complex, BARS binds to and activates a trans-Golgi lysophosphatidic acid (LPA) acyltransferase type δ (LPAATδ) that converts LPA into phosphatidic acid (PA); and that this reaction is essential for fission of the carriers. LPA and PA have unique biophysical properties, and their interconversion might facilitate the fission process either directly or indirectly (via recruitment of proteins that bind to PA, including BARS itself). PMID:27401954

  19. Golgi membrane fission requires the CtBP1-S/BARS-induced activation of lysophosphatidic acid acyltransferase δ.

    PubMed

    Pagliuso, Alessandro; Valente, Carmen; Giordano, Lucia Laura; Filograna, Angela; Li, Guiling; Circolo, Diego; Turacchio, Gabriele; Marzullo, Vincenzo Manuel; Mandrich, Luigi; Zhukovsky, Mikhail A; Formiggini, Fabio; Polishchuk, Roman S; Corda, Daniela; Luini, Alberto

    2016-07-12

    Membrane fission is an essential cellular process by which continuous membranes split into separate parts. We have previously identified CtBP1-S/BARS (BARS) as a key component of a protein complex that is required for fission of several endomembranes, including basolateral post-Golgi transport carriers. Assembly of this complex occurs at the Golgi apparatus, where BARS binds to the phosphoinositide kinase PI4KIIIβ through a 14-3-3γ dimer, as well as to ARF and the PKD and PAK kinases. We now report that, when incorporated into this complex, BARS binds to and activates a trans-Golgi lysophosphatidic acid (LPA) acyltransferase type δ (LPAATδ) that converts LPA into phosphatidic acid (PA); and that this reaction is essential for fission of the carriers. LPA and PA have unique biophysical properties, and their interconversion might facilitate the fission process either directly or indirectly (via recruitment of proteins that bind to PA, including BARS itself).

  20. Lysophosphatidic acid acyltransferase 3 tunes the membrane status of germ cells by incorporating docosahexaenoic acid during spermatogenesis.

    PubMed

    Iizuka-Hishikawa, Yoshiko; Hishikawa, Daisuke; Sasaki, Junko; Takubo, Keiyo; Goto, Motohito; Nagata, Katsuyuki; Nakanishi, Hiroki; Shindou, Hideo; Okamura, Tadashi; Ito, Chizuru; Toshimori, Kiyotaka; Sasaki, Takehiko; Shimizu, Takao

    2017-07-21

    Docosahexaenoic acid (DHA) is one of the essential ω-3 polyunsaturated fatty acids with a wide range of physiological roles important for human health. For example, DHA renders cell membranes more flexible and is therefore important for cellular function, but information on the mechanisms that control DHA levels in membranes is limited. Specifically, it is unclear which factors determine DHA incorporation into cell membranes and how DHA exerts biological effects. We found that lysophosphatidic acid acyltransferase 3 (LPAAT3) is required for producing DHA-containing phospholipids in various tissues, such as the testes and retina. In this study, we report that LPAAT3-KO mice display severe male infertility with abnormal sperm morphology. During germ cell differentiation, the expression of LPAAT3 was induced, and germ cells obtained more DHA-containing phospholipids. Loss of LPAAT3 caused drastic reduction of DHA-containing phospholipids in spermatids that led to excess cytoplasm around its head, which is normally removed by surrounding Sertoli cells via endocytosis at the final stage of spermatogenesis. In vitro liposome filtration assay raised the possibility that DHA in phospholipids promotes membrane deformation that is required for the rapid endocytosis. These data suggest that decreased membrane flexibility in LPAAT3-KO sperm impaired the efficient removal of sperm content through endocytosis. We conclude that LPAAT3-mediated enrichment of cell membranes with DHA-containing phospholipids endows these membranes with physicochemical properties needed for normal cellular processes, as exemplified by spermatogenesis. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.

  1. The Src homology 3 binding domain is required for lysophosphatidic acid 3 receptor-mediated cellular viability in melanoma cells.

    PubMed

    Jia, Wei; Tran, Sterling K; Ruddick, Caitlin A; Murph, Mandi M

    2015-01-28

    The LPA3 receptor is a G protein-coupled receptor that binds extracellular lysophosphatidic acid and mediates intracellular signaling cascades. Although we previously reported that receptor inhibition using siRNA or chemical inhibition obliterates the viability of melanoma cells, the mechanism was unclear. Herein we hypothesized that amino acids comprising the Src homology 3 (SH3) ligand binding motif, R/K-X-X-V/P-X-X-P or (216)-KTNVLSP-(222), within the third intracellular loop of LPA3 were critical in mediating this outcome. Therefore, we performed site-directed mutagenesis of the lysine, valine and proline, replacing these amino acids with alanines, and evaluated the changes in viability, proliferation, ERK1/2 signaling and calcium in response to lysophosphatidic acid. Our results show that enforced LPA3 expression in SK-MEL-2 cells enhanced their resiliency by allowing these cells to oppose any loss of viability during growth in serum-free medium for up to 96 h, in contrast to parental SK-MEL-2 cells, which show a significant decline in viability. Similarly, site-directed alanine substitutions of valine and proline, V219A/P222A or 2aa-SK-MEL-2 cells, did not significantly alter viability, but adding a further alanine to replace the lysine, K216A/V219A/P222A or 3aa-SK-MEL-2 cells, obliterated this function. In addition, an inhibitor of the LPA3 receptor had no impact on the parental SK-MEL-2, 2aa-SK-MEL-2 or 3aa-SK-MEL-2 cells, but significantly reduced viability among wt-LPA3-SK-MEL-2 cells. Taken together, the data suggest that the SH3 ligand binding domain of LPA3 is required to mediate viability in melanoma cells. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

  2. Biodistribution of negatively charged iron oxide nanoparticles (IONPs) in mice and enhanced brain delivery using lysophosphatidic acid (LPA).

    PubMed

    Sun, Zhizhi; Worden, Matthew; Thliveris, James A; Hombach-Klonisch, Sabine; Klonisch, Thomas; van Lierop, Johan; Hegmann, Torsten; Miller, Donald W

    2016-10-01

    Effective treatment of brain disorders requires a focus on improving drug permeability across the blood-brain barrier (BBB). Herein, we examined the pharmacokinetic properties of negatively charged iron oxide nanoparticles (IONPs) and the capability of using lysophosphatidic acid (LPA) to transiently disrupt the tight junctions and allow IONPs to enter the brain. Under normal conditions, IONPs had a plasma half-life of six minutes, with the liver and spleen being the major organs of deposition. Treatment with LPA enhanced accumulation of IONPs in the brain and spleen (approximately 4-fold vs. control). LPA and IONP treated mice revealed no sign of peripheral immune cell infiltration in the brain and no significant activation of microglia or astrocytes. These studies show improved delivery efficiency of IONPs following LPA administration. Our findings suggest transient disruption of the BBB may be a safe and effective method for increasing IONP delivery to the brain. Copyright © 2016 Elsevier Inc. All rights reserved.

  3. Autotaxin activity increases locally following lung injury, but is not required for pulmonary lysophosphatidic acid production or fibrosis

    PubMed Central

    Black, Katharine E.; Berdyshev, Evgeny; Bain, Gretchen; Castelino, Flavia V.; Shea, Barry S.; Probst, Clemens K.; Fontaine, Benjamin A.; Bronova, Irina; Goulet, Lance; Lagares, David; Ahluwalia, Neil; Knipe, Rachel S.; Natarajan, Viswanathan; Tager, Andrew M.

    2016-01-01

    Lysophosphatidic acid (LPA) is an important mediator of pulmonary fibrosis. In blood and multiple tumor types, autotaxin produces LPA from lysophosphatidylcholine (LPC) via lysophospholipase D activity, but alternative enzymatic pathways also exist for LPA production. We examined the role of autotaxin (ATX) in pulmonary LPA production during fibrogenesis in a bleomycin mouse model. We found that bleomycin injury increases the bronchoalveolar lavage (BAL) fluid levels of ATX protein 17-fold. However, the LPA and LPC species that increase in BAL of bleomycin-injured mice were discordant, inconsistent with a substrate-product relationship between LPC and LPA in pulmonary fibrosis. LPA species with longer chain polyunsaturated acyl groups predominated in BAL fluid after bleomycin injury, with 22:5 and 22:6 species accounting for 55 and 16% of the total, whereas the predominant BAL LPC species contained shorter chain, saturated acyl groups, with 16:0 and 18:0 species accounting for 56 and 14% of the total. Further, administration of the potent ATX inhibitor PAT-048 to bleomycin-challenged mice markedly decreased ATX activity systemically and in the lung, without effect on pulmonary LPA or fibrosis. Therefore, alternative ATX-independent pathways are likely responsible for local generation of LPA in the injured lung. These pathways will require identification to therapeutically target LPA production in pulmonary fibrosis.—Black, K. E., Berdyshev, E., Bain, G., Castelino, F. V., Shea, B. S., Probst, C. K., Fontaine, B. A., Bronova, I., Goulet, L., Lagares, D., Ahluwalia, N., Knipe, R. S., Natarajan, V., Tager, A. M. Autotaxin activity increases locally following lung injury, but is not required for pulmonary lysophosphatidic acid production or fibrosis. PMID:27006447

  4. Autotaxin activity increases locally following lung injury, but is not required for pulmonary lysophosphatidic acid production or fibrosis.

    PubMed

    Black, Katharine E; Berdyshev, Evgeny; Bain, Gretchen; Castelino, Flavia V; Shea, Barry S; Probst, Clemens K; Fontaine, Benjamin A; Bronova, Irina; Goulet, Lance; Lagares, David; Ahluwalia, Neil; Knipe, Rachel S; Natarajan, Viswanathan; Tager, Andrew M

    2016-06-01

    Lysophosphatidic acid (LPA) is an important mediator of pulmonary fibrosis. In blood and multiple tumor types, autotaxin produces LPA from lysophosphatidylcholine (LPC) via lysophospholipase D activity, but alternative enzymatic pathways also exist for LPA production. We examined the role of autotaxin (ATX) in pulmonary LPA production during fibrogenesis in a bleomycin mouse model. We found that bleomycin injury increases the bronchoalveolar lavage (BAL) fluid levels of ATX protein 17-fold. However, the LPA and LPC species that increase in BAL of bleomycin-injured mice were discordant, inconsistent with a substrate-product relationship between LPC and LPA in pulmonary fibrosis. LPA species with longer chain polyunsaturated acyl groups predominated in BAL fluid after bleomycin injury, with 22:5 and 22:6 species accounting for 55 and 16% of the total, whereas the predominant BAL LPC species contained shorter chain, saturated acyl groups, with 16:0 and 18:0 species accounting for 56 and 14% of the total. Further, administration of the potent ATX inhibitor PAT-048 to bleomycin-challenged mice markedly decreased ATX activity systemically and in the lung, without effect on pulmonary LPA or fibrosis. Therefore, alternative ATX-independent pathways are likely responsible for local generation of LPA in the injured lung. These pathways will require identification to therapeutically target LPA production in pulmonary fibrosis.-Black, K. E., Berdyshev, E., Bain, G., Castelino, F. V., Shea, B. S., Probst, C. K., Fontaine, B. A., Bronova, I., Goulet, L., Lagares, D., Ahluwalia, N., Knipe, R. S., Natarajan, V., Tager, A. M. Autotaxin activity increases locally following lung injury, but is not required for pulmonary lysophosphatidic acid production or fibrosis. © FASEB.

  5. Both genetic deletion and pharmacological blockade of lysophosphatidic acid LPA1 receptor results in increased alcohol consumption.

    PubMed

    Castilla-Ortega, Estela; Pavón, Francisco Javier; Sánchez-Marín, Laura; Estivill-Torrús, Guillermo; Pedraza, Carmen; Blanco, Eduardo; Suárez, Juan; Santín, Luis; Rodríguez de Fonseca, Fernando; Serrano, Antonia

    2016-04-01

    Lysophosphatidic acid species (LPA) are lipid bioactive signaling molecules that have been recently implicated in the modulation of emotional and motivational behaviors. The present study investigates the consequences of either genetic deletion or pharmacological blockade of lysophosphatidic acid receptor-1 (LPA1) in alcohol consumption. The experiments were performed in alcohol-drinking animals by using LPA1-null mice and administering the LPA1 receptor antagonist Ki16425 in both mice and rats. In the two-bottle free choice paradigm, the LPA1-null mice preferred the alcohol more than their wild-type counterparts. Whereas the male LPA1-null mice displayed this higher preference at all doses tested, the female LPA1-null mice only consumed more alcohol at 6% concentration. The male LPA1-null mice were then further characterized, showing a notably increased ethanol drinking after a deprivation period and a reduced sleep time after acute ethanol administration. In addition, LPA1-null mice were more anxious than the wild-type mice in the elevated plus maze test. For the pharmacological experiments, the acute administration of the antagonist Ki16425 consistently increased ethanol consumption in both wild-type mice and rats; while it did not modulate alcohol drinking in the LPA1-null mice and lacked intrinsic rewarding properties and locomotor effects in a conditioned place preference paradigm. In addition, LPA1-null mice exhibited a marked reduction on the expression of glutamate-transmission-related genes in the prefrontal cortex similar to those described in alcohol-exposed rodents. Results suggest a relevant role for the LPA/LPA1 signaling system in alcoholism. In addition, the LPA1-null mice emerge as a new model for genetic vulnerability to excessive alcohol drinking. The pharmacological manipulation of LPA1 receptor arises as a new target for the study and treatment of alcoholism. Copyright © 2015 Elsevier Ltd. All rights reserved.

  6. LPA1 receptor-mediated thromboxane A2 release is responsible for lysophosphatidic acid-induced vascular smooth muscle contraction.

    PubMed

    Dancs, Péter Tibor; Ruisanchez, Éva; Balogh, Andrea; Panta, Cecília Rita; Miklós, Zsuzsanna; Nüsing, Rolf M; Aoki, Junken; Chun, Jerold; Offermanns, Stefan; Tigyi, Gábor; Benyó, Zoltán

    2017-04-01

    Lysophosphatidic acid (LPA) has been recognized recently as an endothelium-dependent vasodilator, but several lines of evidence indicate that it may also stimulate vascular smooth muscle cells (VSMCs), thereby contributing to vasoregulation and remodeling. In the present study, mRNA expression of all 6 LPA receptor genes was detected in murine aortic VSMCs, with the highest levels of LPA1, LPA2, LPA4, and LPA6 In endothelium-denuded thoracic aorta (TA) and abdominal aorta (AA) segments, 1-oleoyl-LPA and the LPA1-3 agonist VPC31143 induced dose-dependent vasoconstriction. VPC31143-induced AA contraction was sensitive to pertussis toxin (PTX), the LPA1&3 antagonist Ki16425, and genetic deletion of LPA1 but not that of LPA2 or inhibition of LPA3, by diacylglycerol pyrophosphate. Surprisingly, vasoconstriction was also diminished in vessels lacking cyclooxygenase-1 [COX1 knockout (KO)] or the thromboxane prostanoid (TP) receptor (TP KO). VPC31143 increased thromboxane A2 (TXA2) release from TA of wild-type, TP-KO, and LPA2-KO mice but not from LPA1-KO or COX1-KO mice, and PTX blocked this effect. Our findings indicate that LPA causes vasoconstriction in VSMCs, mediated by LPA1-, Gi-, and COX1-dependent autocrine/paracrine TXA2 release and consequent TP activation. We propose that this new-found interaction between the LPA/LPA1 and TXA2/TP pathways plays significant roles in vasoregulation, hemostasis, thrombosis, and vascular remodeling.-Dancs, P. T., Ruisanchez, E., Balogh, A., Panta, C. R., Miklós, Z., Nüsing, R. M., Aoki, J., Chun, J., Offermanns, S., Tigyi, G., Benyó, Z. LPA1 receptor-mediated thromboxane A2 release is responsible for lysophosphatidic acid-induced vascular smooth muscle contraction. © FASEB.

  7. Hydrophilic interaction liquid chromatography-mass spectrometry of (lyso)phosphatidic acids, (lyso)phosphatidylserines and other lipid classes.

    PubMed

    Cífková, Eva; Hájek, Roman; Lísa, Miroslav; Holčapek, Michal

    2016-03-25

    The goal of this work is a systematic optimization of hydrophilic interaction liquid chromatography (HILIC) separation of acidic lipid classes (namely phosphatidic acids-PA, lysophosphatidic acids-LPA, phosphatidylserines-PS and lysophosphatidylserines-LPS) and other lipid classes under mass spectrometry (MS) compatible conditions. The main parameters included in this optimization are the type of stationary phases used in HILIC, pH of the mobile phase, the type and concentration of mobile phase additives. Nine HILIC columns with different chemistries (unmodified silica, modified silica using diol, 2-picolylamine, diethylamine and 1-aminoanthracene and hydride silica) are compared with the emphasis on peak shapes of acidic lipid classes. The optimization of pH is correlated with the theoretical calculation of acidobasic equilibria of studied lipid classes. The final method using the hydride column, pH 4 adjusted by formic acid and the gradient of acetonitrile and 40 mmol/L of aqueous ammonium formate provides good peak shapes for all analyzed lipid classes including acidic lipids. This method is applied for the identification of lipids in real samples of porcine brain and kidney extracts.

  8. Lysophospatidylserine enhances the transfer of 22:6n3 to lysophosphatidic acid in rat brain microsomes

    SciTech Connect

    Rhodes, P.G.; Hu, Zhong-Yi; Sun, G. Y. )

    1991-01-01

    Although the acyl groups of phosphatidylserine in brain are uniquely enriched in docosahexaenoic acid (22:6n3), the mechanism for this enrichment is not well understood. When rat brain homogenates and microsomes were incubated in the presence of lysophosphatidylserine (LPS) together with ({sup 14}C)22:6n3 and cofactors for activation to its acylCoA, very little radioactivity was incorporated into phosphatidylserine (PS). On the other hand, ({sup 14}C)20:4n6 was more actively incorporated into PS. Addition of LPS (1-10 uM), however, resulted in a 2.5 fold enhancement of the transfer of labeled 22:6n3 and 20:4n6 to phosphatidic acid (PA). Kinetic analysis indicated the ability of LPS to lower the Km and increase the Vmax of the lysophosphatidic acid (LPA) acyltransferase reaction. Among other lysophospholipids tested, lysophosphatidylserine was most effective in enhancing PA biosynthesis. Since PA is an important intermediate for de novo biosynthesis of phospholipids, these results reveal a novel mechanism for promoting synthesis of PA enriched in polyunsaturated fatty acids in brain.

  9. Eicosopentaneoic Acid and Other Free Fatty Acid Receptor Agonists Inhibit Lysophosphatidic Acid- and Epidermal Growth Factor-Induced Proliferation of Human Breast Cancer Cells.

    PubMed

    Hopkins, Mandi M; Zhang, Zhihong; Liu, Ze; Meier, Kathryn E

    2016-01-26

    Many key actions of ω-3 (n-3) fatty acids have recently been shown to be mediated by two G protein-coupled receptors (GPCRs) in the free fatty acid receptor (FFAR) family, FFA1 (GPR40) and FFA4 (GPR120). n-3 Fatty acids inhibit proliferation of human breast cancer cells in culture and in animals. In the current study, the roles of FFA1 and FFA4 were investigated. In addition, the role of cross-talk between GPCRs activated by lysophosphatidic acid (LPA), and the tyrosine kinase receptor activated by epidermal growth factor (EGF), was examined. In MCF-7 and MDA-MB-231 human breast cancer cell lines, both LPA and EGF stimulated proliferation, Erk activation, Akt activation, and CCN1 induction. LPA antagonists blocked effects of LPA and EGF on proliferation in MCF-7 and MDA-MB-231, and on cell migration in MCF-7. The n-3 fatty acid eicosopentaneoic acid inhibited LPA- and EGF-induced proliferation in both cell lines. Two synthetic FFAR agonists, GW9508 and TUG-891, likewise inhibited LPA- and EGF-induced proliferation. The data suggest a major role for FFA1, which was expressed by both cell lines. The results indicate that n-3 fatty acids inhibit breast cancer cell proliferation via FFARs, and suggest a mechanism involving negative cross-talk between FFARS, LPA receptors, and EGF receptor.

  10. Eicosopentaneoic Acid and Other Free Fatty Acid Receptor Agonists Inhibit Lysophosphatidic Acid- and Epidermal Growth Factor-Induced Proliferation of Human Breast Cancer Cells

    PubMed Central

    Hopkins, Mandi M.; Zhang, Zhihong; Liu, Ze; Meier, Kathryn E.

    2016-01-01

    Many key actions of ω-3 (n-3) fatty acids have recently been shown to be mediated by two G protein-coupled receptors (GPCRs) in the free fatty acid receptor (FFAR) family, FFA1 (GPR40) and FFA4 (GPR120). n-3 Fatty acids inhibit proliferation of human breast cancer cells in culture and in animals. In the current study, the roles of FFA1 and FFA4 were investigated. In addition, the role of cross-talk between GPCRs activated by lysophosphatidic acid (LPA), and the tyrosine kinase receptor activated by epidermal growth factor (EGF), was examined. In MCF-7 and MDA-MB-231 human breast cancer cell lines, both LPA and EGF stimulated proliferation, Erk activation, Akt activation, and CCN1 induction. LPA antagonists blocked effects of LPA and EGF on proliferation in MCF-7 and MDA-MB-231, and on cell migration in MCF-7. The n-3 fatty acid eicosopentaneoic acid inhibited LPA- and EGF-induced proliferation in both cell lines. Two synthetic FFAR agonists, GW9508 and TUG-891, likewise inhibited LPA- and EGF-induced proliferation. The data suggest a major role for FFA1, which was expressed by both cell lines. The results indicate that n-3 fatty acids inhibit breast cancer cell proliferation via FFARs, and suggest a mechanism involving negative cross-talk between FFARS, LPA receptors, and EGF receptor. PMID:26821052

  11. The effects of aspirin on platelet function and lysophosphatidic acids depend on plasma concentrations of EPA and DHA.

    PubMed

    Block, Robert C; Abdolahi, Amir; Tu, Xin; Georas, Steve N; Brenna, J Thomas; Phipps, Richard P; Lawrence, Peter; Mousa, Shaker A

    2015-05-01

    Aspirin's prevention of cardiovascular disease (CVD) events in individuals with type 2 diabetes mellitus is controversial. Eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) and aspirin all affect the cyclooxygenase enzyme. The relationship between plasma EPA and DHA and aspirin's effects has not been determined. Thirty adults with type 2 diabetes mellitus ingested aspirin (81 mg/day) for 7 days, then EPA+DHA (2.6g/day) for 28 days, then both for another 7 days. Lysophosphatidic acid (LPA) species and more classic platelet function outcomes were determined. Plasma concentrations of total EPA+DHA were associated with 7-day aspirin reduction effects on these outcomes in a "V"-shaped manner for all 11 LPA species and ADP-induced platelet aggregation. This EPA+DHA concentration was quite consistent for each of the LPA species and ADP. These results support aspirin effects on lysolipid metabolism and platelet aggregation depending on plasma EPA+DHA concentrations in individuals with a disturbed lipid milieu. Copyright © 2014 Elsevier Ltd. All rights reserved.

  12. The effects of aspirin on platelet function and lysophosphatidic acids depend on plasma concentrations of EPA and DHA

    PubMed Central

    Block, Robert C; Abdolahi, Amir; Tu, Xin; Georas, Steve N; Brenna, J. Thomas; Phipps, Richard P; Lawrence, Peter; Mousa, Shaker A

    2015-01-01

    Aspirin’s prevention of cardiovascular disease (CVD) events in individuals with type 2 diabetes mellitus is controversial. Eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) and aspirin all affect the cyclooxygenase enzyme. The relationship between plasma EPA and DHA and aspirin’s effects has not been determined. Thirty adults with type 2 diabetes mellitus ingested aspirin (81 mg/day) for 7 days, then EPA+DHA (2.6 g/day) for 28 days, then both for another 7 days. Lysophosphatidic acid (LPA) species and more classic platelet function outcomes were determined. Plasma concentrations of total EPA+DHA were associated with 7-day aspirin reduction effects on these outcomes in a “V”-shaped manner for all 11 LPA species and ADP-induced platelet aggregation. This EPA+DHA concentration was quite consistent for each of the LPA species and ADP. These results support aspirin effects on lysolipid metabolism and platelet aggregation depending on plasma EPA+DHA concentrations in individuals with a disturbed lipid milieu. PMID:25555354

  13. Detection of Serum Lysophosphatidic Acids Using Affinity Binding and Surface Enhanced Laser Deorption/Ionization (SELDI) Time of Flight Mass Spectrometry

    DTIC Science & Technology

    2006-04-01

    Byun H-S., Bittman R., Fan, D., Murph, M., Mills G.B., Tigyi G., 2006 Carba analogs of cyclic phosphatidic acid are selective inhibitors of autotaxin...O OH O P O – O –O O O OH O P O O –O CH2CH2N+(CH3)3 CholineATX/lysoPLD sPLA2 PLA1 Phosphatidic acid (PA) Lysophosphatidic acid (LPA...two distinct enzymatic mechanisms: a | hydrolysis of phosphatidic acid (PA) by soluble phospholipase A2 (sPLA2), which cleaves the fatty acyl chain

  14. Characterization of mouse lysophosphatidic acid acyltransferase 3: an enzyme with dual functions in the testis1s⃞

    PubMed Central

    Yuki, Koichi; Shindou, Hideo; Hishikawa, Daisuke; Shimizu, Takao

    2009-01-01

    Glycerophospholipids are structural and functional components of cellular membranes as well as precursors of various lipid mediators. Using acyl-CoAs as donors, glycerophospholipids are formed by the de novo pathway (Kennedy pathway) and modified in the remodeling pathway (Lands' cycle). Various acyltransferases, including two lysophosphatidic acid acyltransferases (LPAATs), have been discovered from a 1-acylglycerol-3-phosphate O-acyltransferase (AGPAT) family. Proteins of this family contain putative acyltransferase motifs, but their biochemical properties and physiological roles are not completely understood. Here, we demonstrated that mouse LPAAT3, previously known as mouse AGPAT3, possesses strong LPAAT activity and modest lysophosphatidylinositol acyltransferase activity with a clear preference for arachidonoyl-CoA as a donor. This enzyme is highly expressed in the testis, where CDP-diacylglycerol synthase 1 preferring 1-stearoyl-2-arachidonoyl-phosphatidic acid as a substrate is also highly expressed. Since 1-stearoyl-2-arachidonoyl species are the main components of phosphatidylinositol, mouse LPAAT3 may function in both the de novo and remodeling pathways and contribute to effective biogenesis of 1-stearoyl-2-arachidonoyl-phosphatidylinositol in the testis. Additionally, the expression of this enzyme in the testis increases significantly in an age-dependent manner, and β-estradiol may be an important regulator of this enzyme's induction. Our findings identify this acyltransferase as an alternative important enzyme to produce phosphatidylinositol in the testis. PMID:19114731

  15. Type 2 lysophosphatidic acid receptor in gastric surface mucous cells: Possible implication of prostaglandin E2 production.

    PubMed

    Tanaka, Tamotsu; Ohmoto, Mayumi; Morito, Katsuya; Kondo, Hiroki; Urikura, Mai; Satouchi, Kiyoshi; Tokumura, Akira

    2014-01-01

    Lysophosphatidic acid (LPA) is a lipid mediator that induces various cell responses via its specific receptors. Recently, we found that orally administered LPA and phosphatidic acid (PA) ameliorate stress- or aspirin-induced stomach injury. However, the mechanisms underlying these effects have not been elucidated yet. In this study, we examined effect of LPA on prostaglandin (PG) E2 production in MKN74 cells, a gastric cell-line expressing type 2 LPA receptor (LPA2). When the cells were treated with LPA, the level of mRNA of COX-2 but not COX-1 was upregulated. The LPA effect was abolished when the cells were pretreated with pertussis toxin (PTX), suggesting the involvement of receptor(s) coupled with Gi. Pretreatment of MKN74 cells with LPA enhanced the PGE2 production triggered by calcium ionophore A23187. Again, PTX abolished the LPA effect. Fluorescent immunohistochemistry using an antibody against LPA2 showed that surface mucous cells (pit cells) in gastric mucosa of mice express LPA2 on the apical side of the plasma membrane. These results suggest that LPA in the diet or its digestion may contribute to the epithelial integrity of stomach mucosa by enhancement of PGE2 production via activation of LPA2. © 2013 International Union of Biochemistry and Molecular Biology, Inc.

  16. Expression of multiple membrane-associated phospholipase A1 beta transcript variants and lysophosphatidic acid receptors in Ewing tumor cells.

    PubMed

    Schmiedel, Benjamin Joachim; Hutter, Christoph; Hesse, Manuela; Staege, Martin Sebastian

    2011-10-01

    The prognosis for patients with advanced stages of Ewing family tumors (EFT) is very poor. EFT express high levels of phosphatidic acid specific membrane-associated phospholipase A1 beta (lipase I, LIPI). LIPI is a cancer/testis antigen and the high tumor specificity suggests that LIPI might be an attractive target for new diagnostic and/or therapeutic developments. By using reverse transcriptase-polymerase chain reaction (RT-PCR), we observed simultaneous presence of multiple LIPI transcript variants in EFT. We cloned and sequenced these transcript variants from EFT cell lines. Sequence analysis indicated that all transcript variants were derived by alternative splicing. Homology modeling of corresponding protein structures suggested that different transcript variants differ in their regulatory lid domains. In addition, expression of receptors for lysophosphatidic acid (LPA) was analyzed in a panel of EFT cell lines by RT-PCR. We observed that EFT cell lines expressed high levels of LPA receptors. Different LIPI transcript variants present in EFT might be involved in the pathogenesis of EFT by signaling via these LPA receptors.

  17. Lysophosphatidic Acid Mediates Activating Transcription Factor 3 Expression Which Is a Target for Post-Transcriptional Silencing by miR-30c-2-3p

    PubMed Central

    Nguyen, Ha T.; Jia, Wei; Beedle, Aaron M.; Kennedy, Eileen J.; Murph, Mandi M.

    2015-01-01

    Although microRNAs (miRNAs) are small, non-protein-coding entities, they have important roles in post-transcriptional regulation of most of the human genome. These small entities generate fine-tuning adjustments in the expression of mRNA, which can mildly or massively affect the abundance of proteins. Previously, we found that the expression of miR-30c-2-3p is induced by lysophosphatidic acid and has an important role in the regulation of cell proliferation in ovarian cancer cells. The goal here is to confirm that ATF3 mRNA is a target of miR-30c-2-3p silencing, thereby further establishing the functional role of miR-30c-2-3p. Using a combination of bioinformatics, qRT-PCR, immunoblotting and luciferase assays, we uncovered a regulatory pathway between miR-30c-2-3p and the expression of the transcription factor, ATF3. Lysophosphatidic acids triggers the expression of both miR-30c-2-3p and ATF3, which peak at 1 h and are absent 8 h post stimulation in SKOV-3 and OVCAR-3 serous ovarian cancer cells. The 3´-untranslated region (3´-UTR) of ATF3 was a predicted, putative target for miR-30c-2-3p, which we confirmed as a bona-fide interaction using a luciferase reporter assay. Specific mutations introduced into the predicted site of interaction between miR-30c-2-3p and the 3´-UTR of ATF3 alleviated the suppression of the luciferase signal. Furthermore, the presence of anti-miR-30c-2-3p enhanced ATF3 mRNA and protein after lysophosphatidic acid stimulation. Thus, the data suggest that after the expression of ATF3 and miR-30c-2-3p are elicited by lysophosphatidic acid, subsequently miR-30c-2-3p negatively regulates the expression of ATF3 through post-transcriptional silencing, which prevents further ATF3-related outcomes as a consequence of lysophosphatidic acid signaling. PMID:26418018

  18. Lysophosphatidic Acid Mediates Activating Transcription Factor 3 Expression Which Is a Target for Post-Transcriptional Silencing by miR-30c-2-3p.

    PubMed

    Nguyen, Ha T; Jia, Wei; Beedle, Aaron M; Kennedy, Eileen J; Murph, Mandi M

    2015-01-01

    Although microRNAs (miRNAs) are small, non-protein-coding entities, they have important roles in post-transcriptional regulation of most of the human genome. These small entities generate fine-tuning adjustments in the expression of mRNA, which can mildly or massively affect the abundance of proteins. Previously, we found that the expression of miR-30c-2-3p is induced by lysophosphatidic acid and has an important role in the regulation of cell proliferation in ovarian cancer cells. The goal here is to confirm that ATF3 mRNA is a target of miR-30c-2-3p silencing, thereby further establishing the functional role of miR-30c-2-3p. Using a combination of bioinformatics, qRT-PCR, immunoblotting and luciferase assays, we uncovered a regulatory pathway between miR-30c-2-3p and the expression of the transcription factor, ATF3. Lysophosphatidic acids triggers the expression of both miR-30c-2-3p and ATF3, which peak at 1 h and are absent 8 h post stimulation in SKOV-3 and OVCAR-3 serous ovarian cancer cells. The 3´-untranslated region (3´-UTR) of ATF3 was a predicted, putative target for miR-30c-2-3p, which we confirmed as a bona-fide interaction using a luciferase reporter assay. Specific mutations introduced into the predicted site of interaction between miR-30c-2-3p and the 3´-UTR of ATF3 alleviated the suppression of the luciferase signal. Furthermore, the presence of anti-miR-30c-2-3p enhanced ATF3 mRNA and protein after lysophosphatidic acid stimulation. Thus, the data suggest that after the expression of ATF3 and miR-30c-2-3p are elicited by lysophosphatidic acid, subsequently miR-30c-2-3p negatively regulates the expression of ATF3 through post-transcriptional silencing, which prevents further ATF3-related outcomes as a consequence of lysophosphatidic acid signaling.

  19. Lysophosphatidic acid-induced itch is mediated by signaling of LPA5 receptor, phospholipase D and TRPA1/TRPV1.

    PubMed

    Kittaka, Hiroki; Uchida, Kunitoshi; Fukuta, Naomi; Tominaga, Makoto

    2017-02-08

    Intractable and continuous itch sensations often accompany diseases such as atopic dermatitis, neurogenic lesions, uremia and cholestasis. Lysophosphatidic acid (LPA) is an itch mediator found in cholestatic itch patients and it induces acute itch and pain in the experimental rodent models. However, the molecular mechanism by which LPA activates peripheral sensory neurons remains unknown. In this study, we used a cheek injection method in mice to reveal that LPA induced itch-related behaviors but not pain-related behaviors. The LPA-induced itch behavior and cellular effects were dependent on transient receptor potential ankyrin 1 (TRPA1) and vanilloid 1 (TRPV1), which are important for itch signal transduction. We also found that, among the 6 LPA receptors, the LPA5 receptor had the greatest involvement in itching. Furthermore, we demonstrated that phospholipase D (PLD) plays a critical role downstream of LPA5 and that LPA directly and intracellularly activates TRPA1 and TRPV1. These results suggest a unique mechanism that cytoplasmic LPA produced de novo could activate TRPA1 and TRPV1. We conclude that LPA-induced itch is mediated by LPA5 , PLD, TRPA1 and TRPV1 signaling, and thus targeting TRPA1, TRPV1 or PLD could be effective for cholestatic itch interventions. This article is protected by copyright. All rights reserved.

  20. Inhibition of lysophosphatidic acid receptors 1 and 3 attenuates atherosclerosis development in LDL-receptor deficient mice

    PubMed Central

    Kritikou, Eva; van Puijvelde, Gijs H. M.; van der Heijden, Thomas; van Santbrink, Peter J.; Swart, Maarten; Schaftenaar, Frank H.; Kröner, Mara J.; Kuiper, Johan; Bot, Ilze

    2016-01-01

    Lysophosphatidic acid (LPA) is a natural lysophospholipid present at high concentrations within lipid-rich atherosclerotic plaques. Upon local accumulation in the damaged vessels, LPA can act as a potent activator for various types of immune cells through its specific membrane receptors LPA1/3. LPA elicits chemotactic, pro-inflammatory and apoptotic effects that lead to atherosclerotic plaque progression. In this study we aimed to inhibit LPA signaling by means of LPA1/3 antagonism using the small molecule Ki16425. We show that LPA1/3 inhibition significantly impaired atherosclerosis progression. Treatment with Ki16425 also resulted in reduced CCL2 production and secretion, which led to less monocyte and neutrophil infiltration. Furthermore, we provide evidence that LPA1/3 blockade enhanced the percentage of non-inflammatory, Ly6Clow monocytes and CD4+ CD25+ FoxP3+ T-regulatory cells. Finally, we demonstrate that LPA1/3 antagonism mildly reduced plasma LDL cholesterol levels. Therefore, pharmacological inhibition of LPA1/3 receptors may prove a promising approach to diminish atherosclerosis development. PMID:27883026

  1. Loss of lysophosphatidic acid receptor LPA1 alters oligodendrocyte differentiation and myelination in the mouse cerebral cortex.

    PubMed

    García-Díaz, Beatriz; Riquelme, Raquel; Varela-Nieto, Isabel; Jiménez, Antonio Jesús; de Diego, Isabel; Gómez-Conde, Ana Isabel; Matas-Rico, Elisa; Aguirre, José Ángel; Chun, Jerold; Pedraza, Carmen; Santín, Luis Javier; Fernández, Oscar; Rodríguez de Fonseca, Fernando; Estivill-Torrús, Guillermo

    2015-11-01

    Lysophosphatidic acid (LPA) is an intercellular signaling lipid that regulates multiple cellular functions, acting through specific G-protein coupled receptors (LPA(1-6)). Our previous studies using viable Malaga variant maLPA1-null mice demonstrated the requirement of the LPA1 receptor for normal proliferation, differentiation, and survival of the neuronal precursors. In the cerebral cortex LPA1 is expressed extensively in differentiating oligodendrocytes, in parallel with myelination. Although exogenous LPA-induced effects have been investigated in myelinating cells, the in vivo contribution of LPA1 to normal myelination remains to be demonstrated. This study identified a relevant in vivo role for LPA1 as a regulator of cortical myelination. Immunochemical analysis in adult maLPA1-null mice demonstrated a reduction in the steady-state levels of the myelin proteins MBP, PLP/DM20, and CNPase in the cerebral cortex. The myelin defects were confirmed using magnetic resonance spectroscopy and electron microscopy. Stereological analysis limited the defects to adult differentiating oligodendrocytes, without variation in the NG2+ precursor cells. Finally, a possible mechanism involving oligodendrocyte survival was demonstrated by the impaired intracellular transport of the PLP/DM20 myelin protein which was accompanied by cellular loss, suggesting stress-induced apoptosis. These findings describe a previously uncharacterized in vivo functional role for LPA1 in the regulation of oligodendrocyte differentiation and myelination in the CNS, underlining the importance of the maLPA1-null mouse as a model for the study of demyelinating diseases.

  2. P2X7 receptors on osteoblasts couple to production of lysophosphatidic acid: a signaling axis promoting osteogenesis

    PubMed Central

    Panupinthu, Nattapon; Rogers, Joseph T.; Zhao, Lin; Solano-Flores, Luis Pastor; Possmayer, Fred; Sims, Stephen M.; Dixon, S. Jeffrey

    2008-01-01

    Nucleotides are released from cells in response to mechanical stimuli and signal in an autocrine/paracrine manner through cell surface P2 receptors. P2rx7−/− mice exhibit diminished appositional growth of long bones and impaired responses to mechanical loading. We find that calvarial sutures are wider in P2rx7−/− mice. Functional P2X7 receptors are expressed on osteoblasts in situ and in vitro. Activation of P2X7 receptors by exogenous nucleotides stimulates expression of osteoblast markers and enhances mineralization in cultures of rat calvarial cells. Moreover, osteogenesis is suppressed in calvarial cell cultures from P2rx7−/− mice compared with the wild type. P2X7 receptors couple to production of the potent lipid mediators lysophosphatidic acid (LPA) and prostaglandin E2. Either an LPA receptor antagonist or cyclooxygenase (COX) inhibitors abolish the stimulatory effects of P2X7 receptor activation on osteogenesis. We conclude that P2X7 receptors enhance osteoblast function through a cell-autonomous mechanism. Furthermore, a novel signaling axis links P2X7 receptors to production of LPA and COX metabolites, which in turn stimulate osteogenesis. PMID:18519738

  3. Effects of lysophosphatidic acid on the in vitro proliferation and differentiation of a novel porcine preadipocyte cell line.

    PubMed

    Nobusue, Hiroyuki; Kondo, Daisuke; Yamamoto, Makiko; Kano, Koichiro

    2010-12-01

    We examined the effects of lysophosphatidic acid (LPA) on in vitro proliferation and differentiation of a porcine preadipocyte cell line, DFAT-P, and a mouse preadipocyte cell line, 3T3-L1. During the proliferation and differentiation phases, DFAT-P and 3T3-L1 cells expressed only the endothelial differentiation gene (EDG)-2 receptor and not EDG-4 and EDG-7 receptors. LPA promoted the proliferation of DFAT-P cells more extensively than that of 3T3-L1 cells. After adipogenic induction, LPA inhibited glycerol-3-phosphate dehydrogenase activity and lipid droplet accumulation, and suppressed peroxisome proliferator-activated receptor γ (PPARγ) protein expression, this inhibitory effect in DFAT-P cells was twice as high as that in 3T3-L1 cells. Furthermore, treatments with low LPA concentrations significantly inhibited adipocyte differentiation in DFAT-P cells but not in 3T3-L1 cells. We conclude that LPA promotes the proliferation of porcine preadipocytes through the EDG-2 receptor but inhibits their differentiation, and these effects depend on the down-regulation of PPARγ expression via the EDG-2 receptor. Furthermore, DFAT-P cells are more sensitive to LPA than 3T3-L1 cells. These findings in a porcine model will contribute to the understanding of LPA action mechanisms on in vitro proliferation and differentiation of preadipocytes in domestic animals and/or humans.

  4. The effect of lysophosphatidic acid and Rho-associated kinase patterning on adhesion of dental pulp cells.

    PubMed

    Cheng, R; Shao, M-Y; Yang, H; Cheng, L; Wang, F-M; Zhou, X-D; Hu, T

    2011-01-01

    To investigate the effects of lysophosphatidic acid (LPA) and the Rho/Rho-associated kinase (ROCK) pathway on adhesion of dental pulp cells (DPCs). Human DPCs were cultured ex vivo. After treatment of LPA and Y-27632, a specific ROCK inhibitor, changes in focal contacts (FCs) were examined by immunofluorescent staining. Activation of FCs proteins was examined by measuring tyrosine 397 phosphorylation of focal adhesion kinase (FAK) and paxillin using immunoblotting. The data were analysed by Student's t-test. The immunofluorescent staining indicated LPA stimulation induced larger focal adhesion in the cell periphery, compared with the control. Inhibition of ROCK by Y-27632 decreased the formation of FCs markedly, even in the LPA-stimulated cells. LPA also increased the level of tyrosine phosphorylation of paxillin at 30min (P<0.05) and FAK at 5 and 30min (P<0.05). Furthermore, p-paxillin levels declined immediately after Y-27632 treatment and remained low at 5, 30, 60min. Y-27632 also suppressed the effects of LPA on p-paxillin and p-FAK at 5 and 30min (P<0.05). LPA activated Rho and then subsequently activated ROCK, suggesting that LPA influences the FCs of DPCs by modulating tyrosine phosphorylation of FAK and paxillin via the Rho/ROCK pathway. © 2010 International Endodontic Journal.

  5. Lysophosphatidic acid induces reactive oxygen species generation by activating protein kinase C in PC-3 human prostate cancer cells

    SciTech Connect

    Lin, Chu-Cheng; Lin, Chuan-En; Lin, Yueh-Chien; Ju, Tsai-Kai; Huang, Yuan-Li; Lee, Ming-Shyue; Chen, Jiun-Hong; Lee, Hsinyu

    2013-11-01

    Highlights: •LPA induces ROS generation through LPA{sub 1} and LPA{sub 3}. •LPA induces ROS generation by activating PLC. •PKCζ mediates LPA-induced ROS generation. -- Abstract: Prostate cancer is one of the most frequently diagnosed cancers in males, and PC-3 is a cell model popularly used for investigating the behavior of late stage prostate cancer. Lysophosphatidic acid (LPA) is a lysophospholipid that mediates multiple behaviors in cancer cells, such as proliferation, migration and adhesion. We have previously demonstrated that LPA enhances vascular endothelial growth factor (VEGF)-C expression in PC-3 cells by activating the generation of reactive oxygen species (ROS), which is known to be an important mediator in cancer progression. Using flow cytometry, we showed that LPA triggers ROS generation within 10 min and that the generated ROS can be suppressed by pretreatment with the NADPH oxidase (Nox) inhibitor diphenylene iodonium. In addition, transfection with LPA{sub 1} and LPA{sub 3} siRNA efficiently blocked LPA-induced ROS production, suggesting that both receptors are involved in this pathway. Using specific inhibitors and siRNA, phospholipase C (PLC) and protein kinase C (PKC) were also suggested to participate in LPA-induced ROS generation. Overall, we demonstrated that LPA induces ROS generation in PC-3 prostate cancer cells and this is mediated through the PLC/PKC/Nox pathway.

  6. Expression and function of lysophosphatidic acid receptors (LPARs) 1 and 3 in human hepatic cancer progenitor cells.

    PubMed

    Zuckerman, Valentina; Sokolov, Eugene; Swet, Jacob H; Ahrens, William A; Showlater, Victor; Iannitti, David A; Mckillop, Iain H

    2016-01-19

    Hepatocellular carcinoma (HCC) is the most common primary cancer of the liver and is characterized by rapid tumor expansion and metastasis. Lysophosphatidic acid (LPA) signaling, via LPA receptors 1-6 (LPARs1-6), regulates diverse cell functions including motility, migration, and proliferation, yet the role of LPARs in hepatic tumor pathology is poorly understood. We sought to determine the expression and function of endothelial differentiation gene (EDG) LPARs (LPAR1-3) in human HCC and complimentary in vitro models. Human HCC were characterized by significantly elevated LPAR1/LPAR3 expression in the microenvironment between the tumor and non-tumor liver (NTL), a finding mirrored in human SKHep1 cells. Analysis of human tissue and human hepatic tumor cells in vitro revealed cells that express LPAR3 (HCC-NTL margin in vivo and SKHep1 in vitro) also express cancer stem cell markers in the absence of hepatocyte markers. Treatment of SKHep1 cells with exogenous LPA led to significantly increased cell motility but not proliferation. Using pharmacological agents and cells transfected to knock-down LPAR1 or LPAR3 demonstrated LPA-dependent cell migration occurs via an LPAR3-Gi-ERK-pathway independent of LPAR1. These data suggest cells that stain positive for both LPAR3 and cancer stem cell markers are distinct from the tumor mass per se, and may mediate tumor invasiveness/expansion via LPA-LPAR3 signaling.

  7. Definition of a Novel Pathway Centered on Lysophosphatidic Acid To Recruit Monocytes during the Resolution Phase of Tissue Inflammation.

    PubMed

    McArthur, Simon; Gobbetti, Thomas; Kusters, Dennis H M; Reutelingsperger, Christopher P; Flower, Roderick J; Perretti, Mauro

    2015-08-01

    Blood-derived monocytes remove apoptotic cells and terminate inflammation in settings as diverse as atherosclerosis and Alzheimer's disease. They express high levels of the proresolving receptor ALX/FPR2, which is activated by the protein annexin A1 (ANXA1), found in high abundance in inflammatory exudates. Using primary human blood monocytes from healthy donors, we identified ANXA1 as a potent CD14(+)CD16(-) monocyte chemoattractant, acting via ALX/FPR2. Downstream signaling pathway analysis revealed the p38 MAPK-mediated activation of a calcium independent phospholipase A2 with resultant synthesis of lysophosphatidic acid (LPA) driving chemotaxis through LPA receptor 2 and actin cytoskeletal mobilization. In vivo experiments confirmed ANXA1 as an independent phospholipase A2-dependent monocyte recruiter; congruently, monocyte recruitment was significantly impaired during ongoing zymosan-induced inflammation in AnxA1(-/-) or alx/fpr2/3(-/-) mice. Using a dorsal air-pouch model, passive transfer of apoptotic neutrophils between AnxA1(-/-) and wild-type mice identified effete neutrophils as the primary source of soluble ANXA1 in inflammatory resolution. Together, these data elucidate a novel proresolving network centered on ANXA1 and LPA generation and identify previously unappreciated determinants of ANXA1 and ALX/FPR2 signaling in monocytes. Copyright © 2015 The Authors.

  8. Lysophosphatidic Acid Initiates Epithelial to Mesenchymal Transition and Induces β-Catenin-mediated Transcription in Epithelial Ovarian Carcinoma*

    PubMed Central

    Burkhalter, Rebecca J.; Westfall, Suzanne D.; Liu, Yueying; Stack, M. Sharon

    2015-01-01

    During tumor progression, epithelial ovarian cancer (EOC) cells undergo epithelial-to-mesenchymal transition (EMT), which influences metastatic success. Mutation-dependent activation of Wnt/β-catenin signaling has been implicated in gain of mesenchymal phenotype and loss of differentiation in several solid tumors; however, similar mutations are rare in most EOC histotypes. Nevertheless, evidence for activated Wnt/β-catenin signaling in EOC has been reported, and immunohistochemical analysis of human EOC tumors demonstrates nuclear staining in all histotypes. This study addresses the hypothesis that the bioactive lipid lysophosphatidic acid (LPA), prevalent in the EOC microenvironment, functions to regulate EMT in EOC. Our results demonstrate that LPA induces loss of junctional β-catenin, stimulates clustering of β1 integrins, and enhances the conformationally active population of surface β1 integrins. Furthermore, LPA treatment initiates nuclear translocation of β-catenin and transcriptional activation of Wnt/β-catenin target genes resulting in gain of mesenchymal marker expression. Together these data suggest that LPA initiates EMT in ovarian tumors through β1-integrin-dependent activation of Wnt/β-catenin signaling, providing a novel mechanism for mutation-independent activation of this pathway in EOC progression. PMID:26175151

  9. Transgenic Expression of Human Lysophosphatidic Acid Receptor LPA2 in Mouse Intestinal Epithelial Cells Induces Intestinal Dysplasia.

    PubMed

    Yoshida, Michihiro; He, Peijian; Yun, C Chris

    2016-01-01

    Lysophosphatidic acid (LPA) acts on LPA2 receptor to mediate multiple pathological effects that are associated with tumorigenesis. The absence of LPA2 attenuates tumor progression in rodent models of colorectal cancer, but whether overexpression of LPA2 alone can lead to malignant transformation in the intestinal tract has not been studied. In this study, we expressed human LPA2 in intestinal epithelial cells (IECs) under control of the villin promoter. Less than 4% of F1-generation mice had germline transmission of transgenic (TG) human LPA2; as such only 3 F1 mice out of 72 genotyped had TG expression. These TG mice appeared anemic with hematochezia and died shortly after birth. TG mice were smaller in size compared with the wild type mouse of the same age and sex. Morphological analysis showed that TG LPA2 colon had hyper-proliferation of IECs resulting in increased colonic crypt depth. Surprisingly, TG small intestine had villus blunting and decreased IEC proliferation and dysplasia. In both intestine and colon, TG expression of LPA2 compromised the terminal epithelial differentiation, consistent with epithelial dysplasia. Furthermore, we showed that epithelial dysplasia was observed in founder mouse intestine, correlating LPA2 overexpression with epithelial dysplasia. The current study demonstrates that overexpression of LPA2 alone can lead to intestinal dysplasia.

  10. Autotaxin-lysophosphatidic acid-LPA3 signaling at the embryo-epithelial boundary controls decidualization pathways.

    PubMed

    Aikawa, Shizu; Kano, Kuniyuki; Inoue, Asuka; Wang, Jiao; Saigusa, Daisuke; Nagamatsu, Takeshi; Hirota, Yasushi; Fujii, Tomoyuki; Tsuchiya, Soken; Taketomi, Yoshitaka; Sugimoto, Yukihiko; Murakami, Makoto; Arita, Makoto; Kurano, Makoto; Ikeda, Hitoshi; Yatomi, Yutaka; Chun, Jerold; Aoki, Junken

    2017-07-14

    During pregnancy, up-regulation of heparin-binding (HB-) EGF and cyclooxygenase-2 (COX-2) in the uterine epithelium contributes to decidualization, a series of uterine morphological changes required for placental formation and fetal development. Here, we report a key role for the lipid mediator lysophosphatidic acid (LPA) in decidualization, acting through its G-protein-coupled receptor LPA3 in the uterine epithelium. Knockout of Lpar3 or inhibition of the LPA-producing enzyme autotaxin (ATX) in pregnant mice leads to HB-EGF and COX-2 down-regulation near embryos and attenuates decidual reactions. Conversely, selective pharmacological activation of LPA3 induces decidualization via up-regulation of HB-EGF and COX-2. ATX and its substrate lysophosphatidylcholine can be detected in the uterine epithelium and in pre-implantation-stage embryos, respectively. Our results indicate that ATX-LPA-LPA3 signaling at the embryo-epithelial boundary induces decidualization via the canonical HB-EGF and COX-2 pathways. © 2017 The Authors. Published under the terms of the CC BY 4.0 license.

  11. Involvement of aberrant DNA methylation on reduced expression of lysophosphatidic acid receptor-1 gene in rat tumor cell lines

    SciTech Connect

    Tsujiuchi, Toshifumi . E-mail: ttujiuch@life.kindai.ac.jp; Shimizu, Kyoko; Onishi, Mariko; Sugata, Eriko; Fujii, Hiromasa; Mori, Toshio; Honoki, Kanya; Fukushima, Nobuyuki

    2006-10-27

    Lysophosphatidic acid (LPA) is a bioactive phospholipid that stimulates cell proliferation, migration, and protects cells from apoptosis. It interacts with specific G protein-coupled transmembrane receptors. Recently, it has been reported that alterations of LPA receptor expression might be important in the malignant transformation of tumor cells. Therefore, to assess an involvement of DNA methylation in reduced expression of the LPA receptor-1 (lpa1) gene, we investigated the expression of the lpa1 gene and its DNA methylation patterns in rat tumor cell lines. Both rat brain-derived neuroblastoma B103 and liver-derived hepatoma RH7777 cells used in this study indicated no expression of lpa1. For the analysis of methylation status, bisulfite sequencing was performed with B103 and RH7777 cells, comparing with other lpa1 expressed cells and normal tissues of brain and liver. The lpa1 expressed cells and tissues were all unmethylated in this region of lpa1. In contrast, both B103 and RH7777 cells were highly methylated, correlating with reduced expression of the lpa1. Treatment with 5-aza 2'-deoxycytidine induced expression of lpa1 gene in B103 and RH7777 cells after 24 h. In RH7777 cells treated with 5-aza 2'-deoxycytidine, stress fiber formation was also observed in response to LPA in RH7777 cells, but not in untreated RH7777 cells. These results suggest that aberrant DNA methylation of the lpa1 gene may be involved in its reduced expression in rat tumor cells.

  12. Phosphorylation of CREB, a cyclic AMP responsive element binding protein, contributes partially to lysophosphatidic acid-induced fibroblast cell proliferation

    SciTech Connect

    Kwon, Yong-Jun; Sun, Yuanjie; Kim, Nam-Ho; Huh, Sung-Oh

    2009-03-13

    Lysophospholipids regulate a wide array of biological processes including cell survival and proliferation. In our previous studies, we found that in addition to SRE, CRE is required for maximal c-fos promoter activation triggered by lysophosphatidic acid (LPA). c-fos is an early indicator of various cells into the cell cycle after mitogenic stimulation. However, role of CREB activation in LPA-stimulated proliferation has not been elucidated yet. Here, we investigate how LPA induces proliferation in Rat-2 fibroblast cell via CREB activation. We found that total cell number and BrdU-positive cells were increased by LPA. Moreover, levels of c-fos mRNA and cyclin D1 protein were increased via LPA-induced CREB phosphorylation. Furthermore, LPA-induced Rat-2 cell proliferation was decreased markedly by ERK inhibitor (U0126) and partially by MSK inhibitor (H89). Taken together, these results suggest that CREB activation could partially up-regulate accumulation of cyclin D1 protein level and proliferation of LPA-stimulated Rat-2 fibroblast cells.

  13. Adhesion of human platelets to albumin is synergistically increased by lysophosphatidic acid and adrenaline in a donor-dependent fashion.

    PubMed

    Eriksson, Andreas C; Whiss, Per A; Nilsson, Ulrika K

    2006-07-01

    Lysophosphatidic acid (LPA) and adrenaline are weak platelet activators considered important for thrombus formation, and were previously shown to synergistically increase platelet aggregation. Here we investigate synergistic activation by LPA and adrenaline when measuring platelet adhesion. Platelet-rich plasma from healthy blood donors together with adrenaline and/or LPA were added to protein-coated microplates. Platelets were allowed to adhere and the amount of adhesion detected enzymatically. The LPA and adrenaline combination induced a synergistic increase of platelet adhesion to a normally non-adhesive albumin surface. The degree of synergy varied markedly between individuals; these variations could not be explained by age, gender, blood type or different amounts of platelets, oxidized low-density lipoprotein, insulin or glucose in plasma. There was a trend indicating increased synergistic effect for platelets sensitive to adrenaline stimulation. The synergistic effect was blocked by the alpha2-adrenoceptor antagonist yohimbine and inhibited by the ADP scavenger system creatine phosphate/creatine phosphokinase and antibodies against alphaIIbbeta3. Furthermore, platelets adhering to albumin after adrenaline and LPA treatment expressed P-selectin. In conclusion, LPA and adrenaline act synergistically to increase alphaIIbbeta3-mediated platelet adhesion to albumin, dependent on alpha2-adrenoceptor signalling and platelet secretion. We also confirm that synergistic platelet activation achieved with LPA and adrenaline is highly donor dependent.

  14. Lysophosphatidic Acid Triggers Apoptosis in HeLa Cells through the Upregulation of Tumor Necrosis Factor Receptor Superfamily Member 21

    PubMed Central

    2017-01-01

    Lysophosphatidic acid (LPA), a naturally occurring bioactive phospholipid, activates G protein-coupled receptors (GPCRs), leading to regulation of diverse cellular events including cell survival and apoptosis. Despite extensive studies of the signaling pathways that mediate LPA-regulated cell growth and survival, the mechanisms underlying the apoptotic effect of LPA remain largely unclear. In this study, we investigated this issue in HeLa cells. Our data demonstrate that LPA induces apoptosis in HeLa cells at pathologic concentrations with a concomitant upregulation of the expression of TNFRSF21 (tumor necrosis factor receptor superfamily member 21), also known as death receptor number 6 (DR6) involved in inflammation. Moreover, treatment of cells with LPA receptor (LPAR) antagonist abolished the DR6 upregulation by LPA. LPA-induced DR6 expression was also abrogated by pertussis toxin (PTX), an inhibitor of GPCRs, and by inhibitors of PI3K, PKC, MEK, and ERK. Intriguingly, LPA-induced DR6 expression was specifically blocked by dominant-negative form of PKCδ (PKCδ-DN). LPA-induced DR6 expression was also dramatically inhibited by knockdown of ERK or CREB. These results suggest that activation of the MEK/ERK pathway and the transcription factor CREB mediate LPA-induced DR6 expression. More interestingly, knockdown of DR6 using siRNA approach remarkably attenuated LPA-induced apoptosis. In conclusion, our results suggest that LPA-induced apoptosis in HeLa cells is mediated by the upregulation of DR6 expression. PMID:28348459

  15. Theophylline and cAMP inhibit lysophosphatidic acid-induced hyperresponsiveness of bovine tracheal smooth muscle cells

    PubMed Central

    Sakai, Jiro; Oike, Masahiro; Hirakawa, Masakazu; Ito, Yushi

    2003-01-01

    We have established an in vitro model of airway hyperresponsiveness, using a bovine tracheal smooth muscle cell (BTSMC)-embedded collagen gel lattice. When the gel was pretreated with lysophosphatidic acid (LPA), which activates the small G protein RhoA, ATP- and high K+ solution-induced gel contraction was significantly augmented. This was not due to the modulation of Ca2+ mobilizing properties, since ATP- and high K+-induced Ca2+ transients were not significantly different between control and LPA-treated BTSMC. Y-27632, an inhibitor of Rho-kinase, suppressed the LPA-induced augmentation of gel contraction, whereas it did not inhibit the contraction of control gels. Theophylline (> 1 μm) reversed the LPA-induced augmentation of gel contraction, whereas it inhibited control gel contraction only with a very high concentration (100 μm). We confirmed that theophylline increased the intracellular concentration of cAMP ([cAMP]i) in BTSMC. Elevation of [cAMP]i with dibutyryl cAMP or forskolin also reversed the LPA-induced augmentation of gel contraction. Furthermore, theophylline, as well as dibutyryl cAMP and forskolin, suppressed the LPA-induced membrane translocation of RhoA, indicating that they prevented airway hyperresponsiveness by inhibiting RhoA. We conclude from these results that theophylline inhibits LPA-induced, RhoA/Rho-kinase-mediated hyperresponsiveness of tracheal smooth muscle cells due to the accumulation of cAMP. PMID:12679373

  16. Endogenous lysophosphatidic acid participates in vascularisation and decidualisation at the maternal?fetal interface in the rat.

    PubMed

    Sordelli, Micaela S; Beltrame, Jimena S; Zotta, Elsa; Gomez, Natalia; Dmytrenko, Ganna; Sales, María Elena; Blois, Sandra M; Davio, Carlos; Martinez, Silvina Perez; Franchi, Ana M; Ribeiro, María L

    2017-04-05

    Lysophosphatidic acid (LPA) affects several female reproductive functions through G-protein-coupled receptors. LPA contributes to embryo implantation via the lysophospholipid LPA3 receptor. In the present study we investigated the participation of endogenous LPA signalling through the LPA3 receptor in vascularisation and decidualisation, two crucial events at the maternal-fetal interface. Pregnant rats were treated with diacylglycerol pyrophosphate (DGPP), a highly selective antagonist of LPA3 receptors, on Day 5 of gestation. Pregnant rats received intrauterine (i.u.) injections of single doses of DGPP (0.1mgkg-1) in a total volume of 2μL in the left horn (treated horn) in the morning of GD5. DGPP treatment produced aberrant embryo spacing and increased embryo resorption. The LPA3 receptor antagonist decreased the cross-sectional length of the uterine and arcuate arteries and induced histological anomalies in the decidua and placentas. Marked haemorrhagic processes, infiltration of immune cells and tissue disorganisation were observed in decidual and placental tissues from sites of resorption. The mRNA expression of three vascularisation markers, namely interleukin 10 (Il10), vascular endothelial growth factor (Vegfa) and vascular endothelial growth factor receptor 1 (Vegfr1), was reduced at sites of resorption from Day 8. The results show that the disruption of endogenous LPA signalling by blocking the LPA3 receptor modified the development of uterine vessels with consequences in the formation of the decidua and placenta and in the growth of embryos.

  17. Distinct Phospholipase C-β Isozymes Mediate Lysophosphatidic Acid Receptor 1 Effects on Intestinal Epithelial Homeostasis and Wound Closure

    PubMed Central

    Lee, Sei-Jung; Leoni, Giovanna; Neumann, Philipp-Alexander; Chun, Jerold; Nusrat, Asma

    2013-01-01

    Maintenance of the epithelial barrier in the intestinal tract is necessary to protect the host from the hostile luminal environment. Phospholipase C-β (PLC-β) has been implicated to control myriad signaling cascades. However, the biological effects of selective PLC-β isozymes are poorly understood. We describe novel findings that lysophosphatidic acid (LPA) regulates PLC-β1 and PLC-β2 via two distinct pathways to enhance intestinal epithelial cell (IEC) proliferation and migration that facilitate wound closure and recovery of the intestinal epithelial barrier. LPA acting on the LPA1 receptor promotes IEC migration by facilitating the interaction of Gαq with PLC-β2. LPA-induced cell proliferation is PLC-β1 dependent and involves translocation of Gαq to the nucleus, where it interacts with PLC-β1 to induce cell cycle progression. An in vivo study using LPA1-deficient mice (Lpar1−/−) shows a decreased number of proliferating IECs and migration along the crypt-luminal axis. Additionally, LPA enhances migration and proliferation of IECs in an LPA1-dependent manner, and Lpar1−/− mice display defective mucosal wound repair that requires cell proliferation and migration. These findings delineate novel LPA1-dependent lipid signaling that facilitates mucosal wound repair via spatial targeting of distinct PLC-βs within the cell. PMID:23478264

  18. Expression and function of lysophosphatidic acid receptors (LPARs) 1 and 3 in human hepatic cancer progenitor cells

    PubMed Central

    Swet, Jacob H.; Ahrens, William A.; Showlater, Victor; Iannitti, David A.; Mckillop, Iain H.

    2016-01-01

    Hepatocellular carcinoma (HCC) is the most common primary cancer of the liver and is characterized by rapid tumor expansion and metastasis. Lysophosphatidic acid (LPA) signaling, via LPA receptors 1–6 (LPARs1–6), regulates diverse cell functions including motility, migration, and proliferation, yet the role of LPARs in hepatic tumor pathology is poorly understood. We sought to determine the expression and function of endothelial differentiation gene (EDG) LPARs (LPAR1–3) in human HCC and complimentary in vitro models. Human HCC were characterized by significantly elevated LPAR1/LPAR3 expression in the microenvironment between the tumor and non-tumor liver (NTL), a finding mirrored in human SKHep1 cells. Analysis of human tissue and human hepatic tumor cells in vitro revealed cells that express LPAR3 (HCC-NTL margin in vivo and SKHep1 in vitro) also express cancer stem cell markers in the absence of hepatocyte markers. Treatment of SKHep1 cells with exogenous LPA led to significantly increased cell motility but not proliferation. Using pharmacological agents and cells transfected to knock-down LPAR1 or LPAR3 demonstrated LPA-dependent cell migration occurs via an LPAR3-Gi-ERK-pathway independent of LPAR1. These data suggest cells that stain positive for both LPAR3 and cancer stem cell markers are distinct from the tumor mass per se, and may mediate tumor invasiveness/expansion via LPA-LPAR3 signaling. PMID:26701886

  19. Lysophosphatidic acid signaling via LPA1 and LPA3 regulates cellular functions during tumor progression in pancreatic cancer cells.

    PubMed

    Fukushima, Kaori; Takahashi, Kaede; Yamasaki, Eri; Onishi, Yuka; Fukushima, Nobuyuki; Honoki, Kanya; Tsujiuchi, Toshifumi

    2017-03-01

    Lysophosphatidic acid (LPA) signaling via G protein-coupled LPA receptors exhibits a variety of biological effects, such as cell proliferation, motility and differentiation. The aim of this study was to evaluate the roles of LPA1 and LPA3 in cellular functions during tumor progression in pancreatic cancer cells. LPA1 and LPA3 knockdown cells were generated from PANC-1 cells. The cell motile and invasive activities of PANC-1 cells were inhibited by LPA1 and LPA3 knockdown. In gelatin zymography, LPA1 and LPA3 knockdown cells indicated the low activation of matrix metalloproteinase-2 (MMP-2) in the presence of LPA. Next, to assess whether LPA1 and LPA3 regulate cellular functions induced by anticancer drug, PANC-1 cells were treated with cisplatin (CDDP) for approximately 6 months. The cell motile and invasive activities of long-term CDDP treated cells were markedly higher than those of PANC-1 cells, correlating with the expression levels of LPAR1 and LPAR3 genes. In soft agar assay, the long-term CDDP treated cells formed markedly large sized colonies. In addition, the cell motile and invasive activities enhanced by CDDP were significantly suppressed by LPA1 and LPA3 knockdown as well as colony formation. These results suggest that LPA signaling via LPA1 and LPA3 play an important role in the regulation of cellular functions during tumor progression in PANC-1 cells.

  20. Inhibition of lysophosphatidic acid receptors 1 and 3 attenuates atherosclerosis development in LDL-receptor deficient mice.

    PubMed

    Kritikou, Eva; van Puijvelde, Gijs H M; van der Heijden, Thomas; van Santbrink, Peter J; Swart, Maarten; Schaftenaar, Frank H; Kröner, Mara J; Kuiper, Johan; Bot, Ilze

    2016-11-24

    Lysophosphatidic acid (LPA) is a natural lysophospholipid present at high concentrations within lipid-rich atherosclerotic plaques. Upon local accumulation in the damaged vessels, LPA can act as a potent activator for various types of immune cells through its specific membrane receptors LPA1/3. LPA elicits chemotactic, pro-inflammatory and apoptotic effects that lead to atherosclerotic plaque progression. In this study we aimed to inhibit LPA signaling by means of LPA1/3 antagonism using the small molecule Ki16425. We show that LPA1/3 inhibition significantly impaired atherosclerosis progression. Treatment with Ki16425 also resulted in reduced CCL2 production and secretion, which led to less monocyte and neutrophil infiltration. Furthermore, we provide evidence that LPA1/3 blockade enhanced the percentage of non-inflammatory, Ly6C(low) monocytes and CD4(+) CD25(+) FoxP3(+) T-regulatory cells. Finally, we demonstrate that LPA1/3 antagonism mildly reduced plasma LDL cholesterol levels. Therefore, pharmacological inhibition of LPA1/3 receptors may prove a promising approach to diminish atherosclerosis development.

  1. Interaction between Lysophosphatidic Acid, Prostaglandins and the Endocannabinoid System during the Window of Implantation in the Rat Uterus

    PubMed Central

    Sordelli, Micaela S.; Beltrame, Jimena S.; Cella, Maximiliano; Gervasi, María Gracia; Perez Martinez, Silvina; Burdet, Juliana; Zotta, Elsa; Franchi, Ana M.; Ribeiro, María Laura

    2012-01-01

    Bioactive lipid molecules as lysophosphatidic acid (LPA), prostaglandins (PG) and endocannabinoids are important mediators of embryo implantation. Based on previous published data we became interested in studying the interaction between these three groups of lipid derivatives in the rat uterus during the window of implantation. Thus, we adopted a pharmacological approach in vitro using LPA, DGPP (a selective antagonist of LPA3, an LPA receptor), endocannabinoids’ receptor selective antagonists (AM251 and AM630) and non selective (indomethacin) and selective (NS-398) inhibitors of cyclooxygenase-1 and 2 enzymes. Cyclooxygenase isoforms participate in prostaglandins’ synthesis. The incubation of the uterus from rats pregnant on day 5 of gestation (implantation window) with LPA augmented the activity and the expression of fatty acid amide hydrolase, the main enzyme involved in the degradation of endocannabinoids in the rodent uteri, suggesting that LPA decreased endocannabinoids’ levels during embryo implantation. It has been reported that high endocannabinoids are deleterious for implantation. Also, LPA increased PGE2 production and cyclooxygenase-2 expression. The incubation of LPA with indomethacin or NS-398 reversed the increment in PGE2 production, suggesting that cyclooxygenase-2 was the isoform involved in LPA effect. PGs are important mediators of decidualization and vascularization at the implantation sites. All these effects were mediated by LPA3, as the incubation with DGPP completely reversed LPA stimulatory actions. Besides, we also observed that endocannabinoids mediated the stimulatory effect of LPA on cyclooxygenase-2 derived PGE2 production, as the incubation of LPA with AM251 or AM630 completely reversed LPA effect. Also, LPA augmented via LPA3 decidualization and vascularization markers. Overall, the results presented here demonstrate the participation of LPA3 in the process of implantation through the interaction with other groups of lipid

  2. HIF1α-Induced by Lysophosphatidic Acid Is Stabilized via Interaction with MIF and CSN5.

    PubMed

    No, Yi Ran; Lee, Sei-Jung; Kumar, Ajay; Yun, C Chris

    2015-01-01

    Macrophage migration inhibitory factor (MIF) is a cytokine that has broad effects on immune system and inflammatory response. A growing body of evidence implicates the role of MIF in tumor growth and metastasis. Lysophosphatidic acid (LPA), a bioactive lipid mediator, regulates colon cancer cell proliferation, invasion, and survival through LPA2 receptor. Loss of LPA2 results in decreased expression of MIF in a rodent model of colon cancer, but the mechanism of MIF regulation by LPA is yet to be determined. In this study, we show that LPA transcriptionally regulates MIF expression in colon cancer cells. MIF knockdown decreased LPA-mediated proliferation of HCT116 human adenocarcinoma cells without altering the basal proliferation rates. Conversely, extracellular recombinant MIF stimulated cell proliferation, suggesting that the effect of MIF may in part be mediated through activation of surface receptor. We have shown recently that LPA increases hypoxia-inducible factor 1α (HIF1α) expression. We found that MIF regulation by LPA was ablated by knockdown of HIF1α, indicating that MIF is a transcriptional target of HIF1α. Conversely, knockdown of MIF ablated an increase in HIF1α expression in LPA-treated cells, suggesting a reciprocal relationship between HIF1α and MIF. LPA stimulated co-immunoprecipitation of HIF1α and MIF, indicating that their association is necessary for stabilization of HIF1α. It has been shown previously that CSN9 signalosome subunit 5 (CSN5) interacts with HIF1α to stabilize HIF1α under aerobic conditions. We found that LPA did not alter expression of CSN5, but stimulated its interaction with HIF1α and MIF. Depletion of CSN5 mitigated the association between HIF1α and MIF, indicating that CSN5 acts as a physical link. We suggest that HIF1α, MIF, and CSN5 form a ternary complex whose formation is necessary to prevent degradation of HIF1α under aerobic conditions.

  3. HIF1α-Induced by Lysophosphatidic Acid Is Stabilized via Interaction with MIF and CSN5

    PubMed Central

    No, Yi Ran; Lee, Sei-Jung; Kumar, Ajay; Yun, C. Chris

    2015-01-01

    Macrophage migration inhibitory factor (MIF) is a cytokine that has broad effects on immune system and inflammatory response. A growing body of evidence implicates the role of MIF in tumor growth and metastasis. Lysophosphatidic acid (LPA), a bioactive lipid mediator, regulates colon cancer cell proliferation, invasion, and survival through LPA2 receptor. Loss of LPA2 results in decreased expression of MIF in a rodent model of colon cancer, but the mechanism of MIF regulation by LPA is yet to be determined. In this study, we show that LPA transcriptionally regulates MIF expression in colon cancer cells. MIF knockdown decreased LPA-mediated proliferation of HCT116 human adenocarcinoma cells without altering the basal proliferation rates. Conversely, extracellular recombinant MIF stimulated cell proliferation, suggesting that the effect of MIF may in part be mediated through activation of surface receptor. We have shown recently that LPA increases hypoxia-inducible factor 1α (HIF1α) expression. We found that MIF regulation by LPA was ablated by knockdown of HIF1α, indicating that MIF is a transcriptional target of HIF1α. Conversely, knockdown of MIF ablated an increase in HIF1α expression in LPA-treated cells, suggesting a reciprocal relationship between HIF1α and MIF. LPA stimulated co-immunoprecipitation of HIF1α and MIF, indicating that their association is necessary for stabilization of HIF1α. It has been shown previously that CSN9 signalosome subunit 5 (CSN5) interacts with HIF1α to stabilize HIF1α under aerobic conditions. We found that LPA did not alter expression of CSN5, but stimulated its interaction with HIF1α and MIF. Depletion of CSN5 mitigated the association between HIF1α and MIF, indicating that CSN5 acts as a physical link. We suggest that HIF1α, MIF, and CSN5 form a ternary complex whose formation is necessary to prevent degradation of HIF1α under aerobic conditions. PMID:26352431

  4. Lysophosphatidic Acid Up-Regulates Hexokinase II and Glycolysis to Promote Proliferation of Ovarian Cancer Cells1

    PubMed Central

    Mukherjee, Abir; Ma, Yibao; Yuan, Fang; Gong, Yongling; Fang, Zhenyu; Mohamed, Esraa M.; Berrios, Erika; Shao, Huanjie; Fang, Xianjun

    2015-01-01

    Lysophosphatidic acid (LPA), a blood-borne lipid mediator, is present in elevated concentrations in ascites of ovarian cancer patients and other malignant effusions. LPA is a potent mitogen in cancer cells. The mechanism linking LPA signal to cancer cell proliferation is not well understood. Little is known about whether LPA affects glucose metabolism to accommodate rapid proliferation of cancer cells. Here we describe that in ovarian cancer cells, LPA enhances glycolytic rate and lactate efflux. A real time PCR-based miniarray showed that hexokinase II (HK2) was the most dramatically induced glycolytic gene to promote glycolysis in LPA-treated cells. Analysis of the human HK2 gene promoter identified the sterol regulatory element-binding protein as the primary mediator of LPA-induced HK2 transcription. The effects of LPA on HK2 and glycolysis rely on LPA2, an LPA receptor subtype overexpressed in ovarian cancer and many other malignancies. We further examined the general role of growth factor-induced glycolysis in cell proliferation. Like LPA, epidermal growth factor (EGF) elicited robust glycolytic and proliferative responses in ovarian cancer cells. Insulin-like growth factor 1 (IGF-1) and insulin, however, potently stimulated cell proliferation but only modestly induced glycolysis. Consistent with their differential effects on glycolysis, LPA and EGF-dependent cell proliferation was highly sensitive to glycolytic inhibition while the growth-promoting effect of IGF-1 or insulin was more resistant. These results indicate that LPA- and EGF-induced cell proliferation selectively involves up-regulation of HK2 and glycolytic metabolism. The work is the first to implicate LPA signaling in promotion of glucose metabolism in cancer cells. PMID:26476080

  5. Involvement of oncogenic K-ras on cell migration stimulated by lysophosphatidic acid receptor-2 in pancreatic cancer cells.

    PubMed

    Yoshikawa, Kyohei; Tanabe, Eriko; Shibata, Ayano; Inoue, Serina; Kitayoshi, Misaho; Okimoto, Souta; Fukushima, Nobuyuki; Tsujiuchi, Toshifumi

    2013-02-01

    Lysophosphatidic acid (LPA) mediates a variety of cellular responses with atleast six G protein-coupled transmembrane receptors (LPA receptor-1 (LPA(1)-LPA(6))). The interaction between LPA receptors and other cellular molecules on the biological function is not fully understood. Recently, we have reported that LPA(1) suppressed and LPA(3) stimulated cell migration of pancreatic cancer cells. In the present study, to evaluate the function of LPA(2) on motile and invasive activities of pancreatic cancer cells, we generated Lpar2 knockdown (HPD-sh2) cells from hamster pancreatic cancer cells and measured their cell migration ability. In cell motility and invasive assays with an uncoated Cell Culture Insert, HPD-sh2 cells showed significantly lower intrinsic activity than control (HPD-GFP) cells. Since K-ras mutations were frequently detected in pancreatic cancer, we next investigated whether oncogenic K-ras is involved in cell migration induced by LPA(2) using K-ras knockdown (HPD-K2) cells. The cell motile ability of HPD-K2 cells was significantly lower than that of control cells. To confirm LPA(2) increases cell migration activity, cells were pretreated with dioctylglycerol pyrophosphate (DGPP) which is the antagonist of LPA(1)/LPA(3). The cell motile and invasive abilities of DGPP -treated HPD-GFP cells were markedly higher than those of untreated cells, but DGPP did not stimulate cell migration of HPD-K2 cells. These results suggest that cell migration activity of pancreatic cancer cells stimulated by LPA(2) may be enhanced by oncogenic K-ras. Copyright © 2012 Elsevier Inc. All rights reserved.

  6. Deficiency or inhibition of lysophosphatidic acid receptor 1 protects against hyperoxia-induced lung injury in neonatal rats.

    PubMed

    Chen, X; Walther, F J; van Boxtel, R; Laghmani, E H; Sengers, R M A; Folkerts, G; DeRuiter, M C; Cuppen, E; Wagenaar, G T M

    2016-03-01

    Blocking of lysophosphatidic acid (LPA) receptor (LPAR) 1 may be a novel therapeutic option for bronchopulmonary dysplasia (BPD) by preventing the LPAR1-mediated adverse effects of its ligand (LPA), consisting of lung inflammation, pulmonary arterial hypertension (PAH) and fibrosis. In Wistar rats with experimental BPD, induced by continuous exposure to 100% oxygen for 10 days, we determined the beneficial effects of LPAR1 deficiency in neonatal rats with a missense mutation in cytoplasmic helix 8 of LPAR1 and of LPAR1 and -3 blocking with Ki16425. Parameters investigated included survival, lung and heart histopathology, fibrin and collagen deposition, vascular leakage and differential mRNA expression in the lungs of key genes involved in LPA signalling and BPD pathogenesis. LPAR1-mutant rats were protected against experimental BPD and mortality with reduced alveolar septal thickness, lung inflammation (reduced influx of macrophages and neutrophils, and CINC1 expression) and collagen III deposition. However, LPAR1-mutant rats were not protected against alveolar enlargement, increased medial wall thickness of small arterioles, fibrin deposition and vascular alveolar leakage. Treatment of experimental BPD with Ki16425 confirmed the data observed in LPAR1-mutant rats, but did not reduce the pulmonary influx of neutrophils, CINC1 expression and mortality in rats with experimental BPD. In addition, Ki16425 treatment protected against PAH and right ventricular hypertrophy. LPAR1 deficiency attenuates pulmonary injury by reducing pulmonary inflammation and fibrosis, thereby reducing mortality, but does not affect alveolar and vascular development and, unlike Ki16425 treatment, does not prevent PAH in neonatal rats with experimental BPD. © 2015 Scandinavian Physiological Society. Published by John Wiley & Sons Ltd.

  7. Cross-talk between lysophosphatidic acid receptor 1 and tropomyosin receptor kinase A promotes lung epithelial cell migration.

    PubMed

    Nan, Ling; Wei, Jianxin; Jacko, Anastasia M; Culley, Miranda K; Zhao, Jing; Natarajan, Viswanathan; Ma, Haichun; Zhao, Yutong

    2016-02-01

    Lysophosphatidic acid (LPA) is a bioactive lysophospholipid, which plays a crucial role in the regulation of cell proliferation, migration, and differentiation. LPA exerts its biological effects mainly through binding to cell-surface LPA receptors (LPA1-6), which belong to the G protein-coupled receptor (GPCR) family. Recent studies suggest that cross-talk between receptor tyrosine kinases (RTKs) and GPCRs modulates GPCRs-mediated signaling. Tropomyosin receptor kinase A (TrkA) is a RTK, which mediates nerve growth factor (NGF)-induced biological functions including cell migration in neuronal and non-neuronal cells. Here, we show LPA1 transactivation of TrkA in murine lung epithelial cells (MLE12). LPA induced tyrosine phosphorylation of TrkA in both time- and dose-dependent manners. Down-regulation of LPA1 by siRNA transfection attenuated LPA-induced phosphorylation of TrkA, suggesting a cross-talk between LPA1 and TrkA. To investigate the molecular regulation of the cross-talk, we focused on the interaction between LPA1 and TrkA. We found that LPA induced interaction between LPA1 and TrkA. The LPA1/TrkA complex was localized on the plasma membrane and in the cytoplasm. The C-terminus of LPA1 was identified as the binding site for TrkA. Inhibition of TrkA attenuated LPA-induced phosphorylation of TrkA and LPA1 internalization, as well as lung epithelial cell migration. These studies provide a molecular mechanism for the transactivation of TrkA by LPA, and suggest that the cross-talk between LPA1 and TrkA regulates LPA-induced receptor internalization and lung epithelial cell migration. Copyright © 2015 Elsevier B.V. All rights reserved.

  8. Effect of lysophosphatidic acid on the immune inflammatory response and the connexin 43 protein in myocardial infarction

    PubMed Central

    ZHANG, DUODUO; ZHANG, YAN; ZHAO, CHUNYAN; ZHANG, WENJIE; SHAO, GUOGUANG; ZHANG, HONG

    2016-01-01

    Lysophosphatidic acid (LPA) is an intermediate product of membrane phospholipid metabolism. Recently, LPA has gained attention for its involvement in the pathological processes of certain cardiovascular diseases. The aim of the present study was to clarify the association between the effect of LPA and the immune inflammatory response, and to investigate the effects of LPA on the protein expression levels of connexin 43 during myocardial infarction. Surface electrocardiograms of myocardial infarction rats and isolated rat heart tissue samples were obtained in order to determine the effect of LPA on the incidence of arrhythmia in rats that exhibited changes in immune status. The results demonstrated that the incidence of arrhythmia decreased when the rat immune systems were suppressed, and the incidence of arrhythmia increased when the rat immune systems were enhanced. The concentration levels of tumor necrosis factor (TNF)-α were determined by ELISA, and the results demonstrated that LPA induced T lymphocyte synthesis and TNF-α release. Using a patch-clamp technique, LPA was shown to increase the current amplitude of the voltage-dependent potassium channels (Kv) and calcium-activated potassium channels (KCa) in Jurkat T cells. The protein expression of connexin 43 (Cx43) was determined by immunohistochemical staining. The results indicated that LPA caused the degradation of Cx43 and decreased the expression of Cx43. This effect was associated with the immune status of the rats. There was a further decrease in Cx43 expression in the rats of the immune-enhanced group. To the best of our knowledge, these results provide the first evidence that LPA causes arrhythmia through the regulation of immune inflammatory cells and the decrease of Cx43 protein expression. The present study provided an experimental basis for the treatment of arrhythmia and may guide clinical care. PMID:27168781

  9. Regulation of NHE3 by lysophosphatidic acid is mediated by phosphorylation of NHE3 by RSK2.

    PubMed

    No, Yi Ran; He, Peijian; Yoo, Byong Kwon; Yun, C Chris

    2015-07-01

    Na(+)/H(+) exchange by Na(+)/H(+) exchanger 3 (NHE3) is a major route of sodium absorption in the intestine and kidney. We have shown previously that lysophosphatidic acid (LPA), a small phospholipid produced ubiquitously by all types of cells, stimulates NHE3 via LPA5 receptor. Stimulation of NHE3 activity by LPA involves LPA5 transactivating EGF receptor (EGFR) in the apical membrane. EGFR activates proline-rich tyrosine kinase 2 (Pyk2) and ERK, both of which are necessary for NHE3 regulation. However, Pyk2 and ERK are regulated by EGFR via independent pathways and appear to converge on an unidentified intermediate that ultimately targets NHE3. The p90 ribosomal S6 kinase (RSK) family of Ser/Thr protein kinases is a known effector of EGFR and ERK. Hence, we hypothesized that RSK may be the convergent effector of Pyk2 and ERK although it is not known whether Pyk2 regulates RSK. In this study, we show that Pyk2 is necessary for the maintenance of phosphoinositide-dependent kinase 1 (PDK1) autophosphorylation, and knockdown of Pyk2 or PDK1 mitigated LPA-induced phosphorylation of RSK and stimulation of NHE3 activity. Additionally, we show that RSK2, but not RSK1, is responsible for NHE3 regulation. RSK2 interacts with NHE3 at the apical membrane domain, where it phosphorylates NHE3. Alteration of S663 of NHE3 ablated LPA-induced phosphorylation of NHE3 and stimulation of the transport activity. Our study identifies RSK2 as a new kinase that regulates NHE3 activity by direct phosphorylation. Copyright © 2015 the American Physiological Society.

  10. Lysophosphatidic acid increases the proliferation and migration of adipose‑derived stem cells via the generation of reactive oxygen species.

    PubMed

    Kang, Sangjin; Han, Juhee; Song, Seung Yong; Kim, Won-Serk; Shin, Soyoung; Kim, Ji Hye; Ahn, Hyosun; Jeong, Jin-Hyun; Hwang, Sung-Joo; Sung, Jong-Hyuk

    2015-10-01

    Phospholipid derivatives, such as lysophosphatidic acid (LPA), exhibit mitogenic effects on mesenchymal stem cells; however, the molecular mechanism underlying this stimulation has yet to be identified. The aims of the present study were as follows: To evaluate the stimulatory effects of LPA on the proliferation and migration of adipose‑derived stem cells (ASCs); to study the association between reactive oxygen species (ROS) and LPA signaling in ASCs; and to investigate the microRNAs upregulated by LPA treatment in ASCs. The results of the present study demonstrated that LPA increased the proliferation and migration of ASCs, and acted as a mitogenic signal via extracellular signal‑regulated kinases 1/2 and the phosphoinositide 3‑kinase/Akt signaling pathways. The LPA1 receptor is highly expressed in ASCs, and pharmacological inhibition of it by Ki16425 significantly attenuated the proliferation and migration of ASCs. In addition, LPA treatment generated ROS via NADPH oxidase 4, and ROS were able to function as signaling molecules to increase the proliferation and migration of ASCs. The induction of ROS by LPA treatment also upregulated the expression of miR‑210. A polymerase chain reaction array assay demonstrated that the expression levels of adrenomedullin and Serpine1 were increased following treatment with LPA. Furthermore, transfection with Serpine1‑specific small interfering RNA attenuated the migration of ASCs. In conclusion, the present study is the first, to the best of our knowledge, to report that ROS generation and miR‑210 expression are associated with the LPA‑induced stimulation of ASCs, and that Serpine1 mediates the LPA‑induced migration of ASCs. These results further suggest that LPA may be used for ASC stimulation during stem cell expansion.

  11. Endogenous lysophosphatidic acid (LPA1 ) receptor agonists demonstrate ligand bias between calcium and ERK signalling pathways in human lung fibroblasts.

    PubMed

    Sattikar, Afrah; Dowling, Mark R; Rosethorne, Elizabeth M

    2017-02-01

    Human lung fibroblasts (HLF) express high levels of the LPA1 receptor, a GPCR that responds to the endogenous lipid mediator, lysophosphatidic acid (LPA). Several molecular species or analogues of LPA exist and have been detected in biological fluids such as serum and plasma. The most widely expressed of the LPA receptor family is the LPA1 receptor, which predominantly couples to Gq/11 , Gi/o and G12/13 proteins. This promiscuity of coupling raises the possibility that some of the LPA analogues may bias the LPA1 receptor towards one signalling pathway over another. Here, we have explored the signalling profiles of a range of LPA analogues in HLF that endogenously express the LPA1 receptor. HLF were treated with LPA analogues and receptor activation monitored via calcium mobilization and ERK phosphorylation. These analyses demonstrated that the 16:0, 17:0, 18:2 and C18:1 LPA analogues appear to exhibit ligand bias between ERK phosphorylation and calcium mobilization when compared with 18:1 LPA, one of the most abundant forms of LPA that has been found in human plasma. The importance of LPA as a key signalling molecule is shown by its widespread occurrence in biological fluids and its association with disease conditions such as fibrosis and cancer. These findings have important, as yet unexplored, implications for the (patho-) physiological signalling of the LPA1 receptor, as it may be influenced not only by the concentration of endogenous ligand but the isoform as well. © 2016 The British Pharmacological Society.

  12. Lysophosphatidic acid receptor type 1 (LPA1) plays a functional role in osteoclast differentiation and bone resorption activity.

    PubMed

    David, Marion; Machuca-Gayet, Irma; Kikuta, Junichi; Ottewell, Penelope; Mima, Fuka; Leblanc, Raphael; Bonnelye, Edith; Ribeiro, Johnny; Holen, Ingunn; Lopez Vales, Rùben; Jurdic, Pierre; Chun, Jerold; Clézardin, Philippe; Ishii, Masaru; Peyruchaud, Olivier

    2014-03-07

    Lysophosphatidic acid (LPA) is a natural bioactive lipid that acts through six different G protein-coupled receptors (LPA1-6) with pleiotropic activities on multiple cell types. We have previously demonstrated that LPA is necessary for successful in vitro osteoclastogenesis of bone marrow cells. Bone cells controlling bone remodeling (i.e. osteoblasts, osteoclasts, and osteocytes) express LPA1, but delineating the role of this receptor in bone remodeling is still pending. Despite Lpar1(-/-) mice displaying a low bone mass phenotype, we demonstrated that bone marrow cell-induced osteoclastogenesis was reduced in Lpar1(-/-) mice but not in Lpar2(-/-) and Lpar3(-/-) animals. Expression of LPA1 was up-regulated during osteoclastogenesis, and LPA1 antagonists (Ki16425, Debio0719, and VPC12249) inhibited osteoclast differentiation. Blocking LPA1 activity with Ki16425 inhibited expression of nuclear factor of activated T-cell cytoplasmic 1 (NFATc1) and dendritic cell-specific transmembrane protein and interfered with the fusion but not the proliferation of osteoclast precursors. Similar to wild type osteoclasts treated with Ki16425, mature Lpar1(-/-) osteoclasts had reduced podosome belt and sealing zone resulting in reduced mineralized matrix resorption. Additionally, LPA1 expression markedly increased in the bone of ovariectomized mice, which was blocked by bisphosphonate treatment. Conversely, systemic treatment with Debio0719 prevented ovariectomy-induced cancellous bone loss. Moreover, intravital multiphoton microscopy revealed that Debio0719 reduced the retention of CX3CR1-EGFP(+) osteoclast precursors in bone by increasing their mobility in the bone marrow cavity. Overall, our results demonstrate that LPA1 is essential for in vitro and in vivo osteoclast activities. Therefore, LPA1 emerges as a new target for the treatment of diseases associated with excess bone loss.

  13. Lysophosphatidic acid increases the production of pivotal mediators of decidualization and vascularization in the rat uterus.

    PubMed

    Beltrame, J S; Sordelli, M S; Cella, M; Perez Martinez, S; Franchi, A M; Ribeiro, M L

    2013-09-01

    The decidual reaction and the formation of new vessels in the uterus are two crucial processes during embryo implantation. Previously, we observed that lysophosphatidic acid (LPA) increases cyclooxygenase-2 derived - prostaglandin E2 production during implantation in the rat uterus and that it augments the expression of decidualization (IGFBP-1) and vascularization (IL-10) markers. Both cyclooxygenase and nitric oxide synthase (NOS) are known enzymes involved in these processes. Thus, we became interested in studying which factors contribute to LPA receptor-specific role during the decidual and the vascular reaction at implantation. We adopted a pharmacological approach in vitro incubating the uterus from rats on day 5 of gestation (day of implantation) with LPA, DGPP (a highly selective antagonist of LPA3, an LPA receptor) and cyclooxygenase and NOS selective and non-selective inhibitors. We determined NOS activity, prostaglandin E2 production and IGFBP-1 and IL-10 expression to evaluate decidualization and vascularization. We observed that LPA augmented the activity of the inducible NOS isoform through LPA1/LPA3. Inducible NOS activity participated in the induction of cyclooxygenase-2/prostaglandin E2 increase stimulated by LPA. Also, cyclooxygenase-2 derived prostaglandins mediated LPA-stimulatory action on NOS activity. Both cyclooxygenase-2 and inducible NOS mediated LPA effect on IGFBP-1 and IL-10 expression. These results suggest the participation of LPA/LPA3 in the production of crucial molecules involved in vascularization and decidualization, two main processes that prepare the uterine milieu for embryo invasion during implantation. Copyright © 2013 Elsevier Ltd. All rights reserved.

  14. Antifibrotic effect of lysophosphatidic acid receptors LPA1 and LPA3 antagonist on experimental murine scleroderma induced by bleomycin.

    PubMed

    Ohashi, Takenobu; Yamamoto, Toshiyuki

    2015-09-01

    The study of lysophosphatidic acid (LPA) receptor has recently focused on its involvement in the pathogenesis of systemic sclerosis (SSc). We examined the inhibitory effects of the antagonist for the LPA receptor, a selective LPA1 and LPA3 antagonist (Ki16425), on dermal and lung fibrosis in a mouse model of SSc. Ki16425 was administered intra-dermally after 6 h on the same sites as bleomycin injection. Histopathological examination showed that skin lesions were markedly attenuated by treatment with Ki16425 at doses of 1 and 10 mg/kg, along with reduced dermal thickness. Hydroxyproline contents in the Ki16425-treated skin showed a decrease of 35% (1 mg/kg) and 45% (10 mg/kg) compared with those in the oil-injected skin of the controls. The number of mast cells and phospho-Smad2/3-positive spindle cells of the Ki16425-treated skin was significantly decreased compared with that in the controls. Additionally, RT-PCR analysis showed that the mRNA levels of TGF-β1, CTGF, MIP-1α, IFN-γ and collagen α1(I) were significantly decreased in both the 1-mg/kg and 10-mg/kg groups of the Ki16425-treated mice compared with those in the controls. Furthermore, treatment with bleomycin and Ki16425 showed reduction in lung fibrosis, and the hydroxyproline contents in the lungs of the Ki16425-treated mice showed a decrease of 25% (1 mg/kg) and 32% (10 mg/kg) compared with those in the lungs of the controls. Taken together, Ki16425 was found to improve dermal and lung fibrosis in a mouse model of bleomycin-induced murine scleroderma. These results suggest that Ki16425 has the potential to be an effective new treatment for scleroderma. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  15. Lysophosphatidic Acid and Sphingosine-1-Phosphate: A Concise Review of Biological Function and Applications for Tissue Engineering

    PubMed Central

    Binder, Bernard Y.K.; Williams, Priscilla A.

    2015-01-01

    The presentation and controlled release of bioactive signals to direct cellular growth and differentiation represents a widely used strategy in tissue engineering. Historically, work in this field has primarily focused on the delivery of large cytokines and growth factors, which can be costly to manufacture and difficult to deliver in a sustained manner. There has been a marked increase over the past decade in the pursuit of lipid mediators due to their wide range of effects over multiple cell types, low cost, and ease of scale-up. Lysophosphatidic acid (LPA) and sphingosine-1-phosphate (S1P) are two bioactive lysophospholipids (LPLs) that have gained attention for use as pharmacological agents in tissue engineering applications. While these lipids can have similar effects on cellular response, they possess distinct chemical backbones, mechanisms of synthesis and degradation, and signaling pathways using a discrete set of G-protein-coupled receptors (GPCRs). LPA and S1P predominantly act extracellularly on their GPCRs and can directly regulate cell survival, differentiation, cytokine secretion, proliferation, and migration—each of the important functions that must be considered in regenerative medicine. In addition to these potent physiological functions, these LPLs play pivotal roles in a number of pathophysiological processes. To capitalize on the promise of these molecules in tissue engineering, these lipids have been incorporated into biomaterials for in vivo delivery. Here, we survey the effects of LPA and S1P on both cellular- and tissue-level phenotypes, with an eye toward regulating stem/progenitor cell growth and differentiation. In particular, we examine work that has translational applications for cell-based tissue engineering strategies in promoting cell survival, bone and cartilage engineering, and therapeutic angiogenesis. PMID:26035484

  16. Expression of autotaxin and lysophosphatidic acid receptors 1 and 3 in the developing rat lung and in response to hyperoxia.

    PubMed

    Shim, G H; Kim, H-S; Kim, E S; Lee, K-Y; Kim, E-K; Choi, J-H

    2015-01-01

    We sought to evaluate lysophosphatidic acid (LPA) signaling improvement in lung development by assessing the expression of autotaxin and LPA receptor 1 and 3 (LPAR1 and LPAR3) in the neonatal rat lung during normal perinatal development and in response to hyperoxia. In the developmental study, rats were sacrificed on days 17, 19, and 21 of gestation; on postnatal days 1, 4, and 7; and at adulthood (postnatal 9 weeks). In the hyperoxia study, 42 postnatal 4-day-old rat pups were divided into seven groups and exposed to either 85% O2 for 24, 72, or 120 h or room air for 0, 24, 72, or 120 h. The rats were then euthanized after 0, 24, 72, and 120 h of exposure. Immunofluorescence demonstrated that autotaxin, LPAR1, and LPAR3 proteins were broadly colocalized in airway epithelial cells, but mainly distributed in vascular endothelial and mesenchymal cells during the first postnatal week. The expression of autotaxin, LPAR1, and LPAR3 were increased during late gestation and then decreased after birth. Autotaxin expression and enzymatic activity were significantly increased at 72 and 120 h after exposure to hyperoxia. LPAR1 and LPAR3 expression was also increased after 120 h of hyperoxic exposure. These findings suggest that LPA-associated molecules were upregulated at birth and induced by hyperoxia in the developing rat lung. Therefore, the LPA pathway may be involved in normal lung development, including vascular development, as well as wound-healing processes of injured neonatal lung tissue, which is at risk of neonatal hyperoxic acute lung injury.

  17. Lysophosphatidic Acid and Sphingosine-1-Phosphate: A Concise Review of Biological Function and Applications for Tissue Engineering.

    PubMed

    Binder, Bernard Y K; Williams, Priscilla A; Silva, Eduardo A; Leach, J Kent

    2015-12-01

    The presentation and controlled release of bioactive signals to direct cellular growth and differentiation represents a widely used strategy in tissue engineering. Historically, work in this field has primarily focused on the delivery of large cytokines and growth factors, which can be costly to manufacture and difficult to deliver in a sustained manner. There has been a marked increase over the past decade in the pursuit of lipid mediators due to their wide range of effects over multiple cell types, low cost, and ease of scale-up. Lysophosphatidic acid (LPA) and sphingosine-1-phosphate (S1P) are two bioactive lysophospholipids (LPLs) that have gained attention for use as pharmacological agents in tissue engineering applications. While these lipids can have similar effects on cellular response, they possess distinct chemical backbones, mechanisms of synthesis and degradation, and signaling pathways using a discrete set of G-protein-coupled receptors (GPCRs). LPA and S1P predominantly act extracellularly on their GPCRs and can directly regulate cell survival, differentiation, cytokine secretion, proliferation, and migration--each of the important functions that must be considered in regenerative medicine. In addition to these potent physiological functions, these LPLs play pivotal roles in a number of pathophysiological processes. To capitalize on the promise of these molecules in tissue engineering, these lipids have been incorporated into biomaterials for in vivo delivery. Here, we survey the effects of LPA and S1P on both cellular- and tissue-level phenotypes, with an eye toward regulating stem/progenitor cell growth and differentiation. In particular, we examine work that has translational applications for cell-based tissue engineering strategies in promoting cell survival, bone and cartilage engineering, and therapeutic angiogenesis.

  18. Regulation of NHE3 by lysophosphatidic acid is mediated by phosphorylation of NHE3 by RSK2

    PubMed Central

    No, Yi Ran; He, Peijian; Yoo, Byong Kwon

    2015-01-01

    Na+/H+ exchange by Na+/H+ exchanger 3 (NHE3) is a major route of sodium absorption in the intestine and kidney. We have shown previously that lysophosphatidic acid (LPA), a small phospholipid produced ubiquitously by all types of cells, stimulates NHE3 via LPA5 receptor. Stimulation of NHE3 activity by LPA involves LPA5 transactivating EGF receptor (EGFR) in the apical membrane. EGFR activates proline-rich tyrosine kinase 2 (Pyk2) and ERK, both of which are necessary for NHE3 regulation. However, Pyk2 and ERK are regulated by EGFR via independent pathways and appear to converge on an unidentified intermediate that ultimately targets NHE3. The p90 ribosomal S6 kinase (RSK) family of Ser/Thr protein kinases is a known effector of EGFR and ERK. Hence, we hypothesized that RSK may be the convergent effector of Pyk2 and ERK although it is not known whether Pyk2 regulates RSK. In this study, we show that Pyk2 is necessary for the maintenance of phosphoinositide-dependent kinase 1 (PDK1) autophosphorylation, and knockdown of Pyk2 or PDK1 mitigated LPA-induced phosphorylation of RSK and stimulation of NHE3 activity. Additionally, we show that RSK2, but not RSK1, is responsible for NHE3 regulation. RSK2 interacts with NHE3 at the apical membrane domain, where it phosphorylates NHE3. Alteration of S663 of NHE3 ablated LPA-induced phosphorylation of NHE3 and stimulation of the transport activity. Our study identifies RSK2 as a new kinase that regulates NHE3 activity by direct phosphorylation. PMID:25855080

  19. Molecular characterization of PS-341 (bortezomib) resistance: implications for overcoming resistance using lysophosphatidic acid acyltransferase (LPAAT)-beta inhibitors.

    PubMed

    Hideshima, Teru; Chauhan, Dharminder; Ishitsuka, Kenji; Yasui, Hiroshi; Raje, Noopur; Kumar, Shaji; Podar, Klaus; Mitsiades, Constantine; Hideshima, Hiromasa; Bonham, Lynn; Munshi, Nikhil C; Richardson, Paul G; Singer, Jack W; Anderson, Kenneth C

    2005-04-28

    PS-341 (bortezomib, Velcadetrade mark) is a promising novel agent for treatment of advanced multiple myeloma (MM); however, 65% of patients with relapsed refractory disease in a phase II study do not respond to PS-341. We have previously shown that lysophosphatidic acid acyltransferase (LPAAT)-beta inhibitor CT-32615 triggers caspase-dependent apoptosis, and can overcome resistance to conventional therapeutics (i.e., dexamethasone, doxorubicin, melphalan) in MM cells. In this study, we therefore determined whether CT-32615 could also overcome resistance to PS-341. We first characterized molecular mechanisms of resistance to PS-341 in DHL-4 cells. DHL-4 cells express low levels of caspase-3 and caspase-8; furthermore, no cleavage in caspase-8, caspase-9, caspase-3, poly ADP-ribose polymerase (PARP), or DNA fragmentation factor 45 was triggered by PS-341 treatment. We have previously shown that PS-341 treatment triggers phosphorylation of c-Jun NH(2)-terminal kinase (JNK), which subsequently induces caspase-dependent apoptosis; conversely, JNK inhibition blocks PS-341-induced apoptosis. We here show that phosphorylation of SEK-1, JNK, and c-Jun are not induced by PS-341 treatment, suggesting that PS-341 does not trigger a stress response in DHL-4 cells. Importantly, CT-32615 inhibits growth of DHL-4 cells in a time- and dose-dependent fashion: a transient G2/M cell cycle arrest induced by CT-32615 is mediated via downregulation of cdc25c and cdc2. CT-32615 triggered swelling and lysis of DHL-4 cells, without caspase/PARP cleavage or TUNEL-positivity, suggesting a necrotic response. Our studies therefore demonstrate that LPAAT-beta inhibitor CT-32615 triggers necrosis, even in PS-341-resistant DHL-4 cells, providing the framework for its evaluation to overcome clinical PS-341 resistance and improve patient outcome.

  20. Downstream molecular events in the altered profiles of lysophosphatidic acid-induced cAMP in senescent human diploid fibroblasts.

    PubMed

    Jang, Ik Soon; Rhim, Ji Heon; Park, Sang Chul; Yeo, Eui Ju

    2006-04-30

    Lysophosphatidic acid (LPA) is a phospholipid growth factor that acts through G-protein-coupled receptors. Previously, we demonstrated an altered profile of LPA-dependent cAMP content during the aging process of human diploid fibroblasts (HDFs). In attempts to define the molecular events associated with the age-dependent changes in cAMP profiles, we determined the protein kinase A (PKA) activity, phosphorylation of cAMP-response element binding protein (CREB), and the protein expression of CRE-regulatory genes, c-fos and COX-2 in young and senescent HDFs. We observed in senescent cells, an increase in mRNA levels of the catalytic subunit a of PKA and of the major regulatory subunit Ialpha. Senescence-associated increase of cAMP after LPA treatment correlated well with increased CREB phosphorylation accompanying activation of PKA in senescent cells. In senescent cells, after LPA treatment, the expression of c-fos and COX-2 decreased initially, followed by an increase. In young HDFs, CREB phosphorylation decreased following LPA treatment, and both c-fos and COX-2 protein levels increased rapidly. CRE-luciferase assay revealed higher basal CRE-dependent gene expression in young HDFs compared to senescent HDFs. However, LPA-dependent slope of luciferase increased more rapidly in senescent cells than in young cells, presumably due to an increase of LPA-induced CREB phosphorylation. CRE-dependent luciferase activation was abrogated in the presence of inhibitors of PKC, MEK1, p38MAPK, and PKA, in both young and senescent HDFs. We conclude that these kinase are coactivators of the expression of CRE-responsive genes in LPA-induced HDFs and that their changed activities during the aging process contribute to the final expression level of CRE-responsive genes.

  1. Mitigation of the hematopoietic and gastrointestinal acute radiation syndrome by octadecenyl thiophosphate, a small molecule mimic of lysophosphatidic acid.

    PubMed

    Deng, Wenlin; Kimura, Yasuhiro; Gududuru, Veeresh; Wu, Wenjie; Balogh, Andrea; Szabo, Erzsebet; Thompson, Karin Emmons; Yates, C Ryan; Balazs, Louisa; Johnson, Leonard R; Miller, Duane D; Strobos, Jur; McCool, W Shannon; Tigyi, Gabor J

    2015-04-01

    We have previously demonstrated that the small molecule octadecenyl thiophosphate (OTP), a synthetic mimic of the growth factor-like mediator lysophosphatidic acid (LPA), showed radioprotective activity in a mouse model of total-body irradiation (TBI) when given orally or intraperitoneally 30 min before exposure to 9 Gy γ radiation. In the current study, we evaluated the effects of OTP, delivered subcutaneously, for radioprotection or radiomitigation from -24 h before to up to +72 h postirradiation using a mouse TBI model with therapeutic doses at around 1 mg/kg. OTP was injected at 10 mg/kg without observable toxic side effects in mice, providing a comfortable safety margin. Treatment of C57BL/6 mice with a single dose of OTP over the time period from -12 h before to +26 h after a lethal dose of TBI reduced mortality by 50%. When administered at +48 h to +72 h postirradiation (LD50/30 to LD100/30), OTP reduced mortality by ≥34%. OTP administered at +24 h postirradiation significantly elevated peripheral white blood cell and platelet counts, increased crypt survival in the jejunum, enhanced intestinal glucose absorption and reduced endotoxin seepage into the blood. In the 6.4-8.6 Gy TBI range using LD50/10 as the end point, OTP yielded a dose modification factor of 1.2. The current data indicate that OTP is a potent radioprotector and radiomitigator ameliorating the mortality and tissue injury of acute hematopoietic as well as acute gastrointestinal radiation syndrome.

  2. Spinal cord compression injury in lysophosphatidic acid 1 receptor-null mice promotes maladaptive pronociceptive descending control.

    PubMed

    Suardíaz, M; Galan-Arriero, I; Avila-Martin, G; Estivill-Torrús, G; de Fonseca, F R; Chun, J; Gómez-Soriano, J; Bravo-Esteban, E; Taylor, J

    2016-02-01

    Although activation of the lysophosphatidic acid receptor 1 (LPA1) is known to mediate pronociceptive effects in peripheral pain models, the role of this receptor in the modulation of spinal nociception following spinal cord injury (SCI) is unknown. In this study, LPA1 regulation of spinal excitability mediated by supraspinal descending antinociceptive control systems was assessed following SCI in both wild-type (WT) and maLPA1-null receptor mice. The effect of a T8 spinal compression in WT and maLPA1-null mice was assessed up to 1 month after SCI using histological, immunohistochemical and behavioural techniques analysis including electrophysiological recording of noxious toes-Tibialis Anterior (TA) stimulus-response reflex activity. The effect of a T3 paraspinal transcutaneous electrical conditioning stimulus on TA noxious reflex temporal summation was also assessed. Histological analysis demonstrated greater dorsolateral funiculus damage after SCI in maLPA1-null mice, without a change in the stimulus-response function of the TA noxious reflex when compared to WT mice. While T3 conditioning stimulation in the WT group inhibited noxious TA reflex temporal summation after SCI, this stimulus strongly excited TA reflex temporal summation in maLPA1-null mice. The functional switch from descending inhibition to maladaptive facilitation of central excitability of spinal nociception demonstrated in maLPA1-null mice after SCI was unrelated to a general change in reflex activity. These data suggest that the LPA1 receptor is necessary for inhibition of temporal summation of noxious reflex activity, partly mediated via long-tract descending modulatory systems acting at the spinal level. © 2015 European Pain Federation - EFIC®

  3. Lysophosphatidic acid (LPA) signaling via LPA4 and LPA6 negatively regulates cell motile activities of colon cancer cells.

    PubMed

    Takahashi, Kaede; Fukushima, Kaori; Onishi, Yuka; Inui, Karin; Node, Yusuke; Fukushima, Nobuyuki; Honoki, Kanya; Tsujiuchi, Toshifumi

    2017-01-29

    Lysophosphatidic acid (LPA) is an extracellular biological lipid and interacts with six subtypes of G protein-coupled LPA receptors (LPA1 to LPA6). LPA receptors exhibit a variety of cellular functions, depending on types of cancer cells. In this study, to assess the roles of LPA4 and LPA6 in cell growth and motile activities of colon cancer cells, LPA4 and LPA6 knockdown cells were established from DLD1 and HCT116 cells. LPA treatment increased the cell growth activities of LPA4 and LPA6 knockdown cells, compared with control cells. The cell motile activities of LPA4 and LPA6 knockdown cells were significantly higher than those of control cells. To evaluate the effects of LPA4 and LPA6 on cell motile activity induced by anticancer drug, long-term fluorouracil (5-FU) treated (DLD-5FU) cells were generated. The expression levels of LPAR1, LPAR4 and LPAR6 genes were significantly increased in DLD-5FU cells. DLD-5FU cells showed the high cell motile activity, compared with DLD1 cells. The increased cell motile activity was markedly stimulated by LPA4 and LPA6 knockdown. In contrast, the cell motile activity enhanced by 5-FU treatment was suppressed by LPA1 knockdown. These results suggest that LPA signaling via LPA4 and LPA6 negatively regulates the cell motile activities of DLD1 and HCT116 cells as well as long-term 5-FU treated cells. Copyright © 2016 Elsevier Inc. All rights reserved.

  4. Lysophosphatidic acid upregulates connective tissue growth factor expression in osteoblasts through the GPCR/PKC and PKA pathways.

    PubMed

    Yu, Zi-Li; Li, Dian-Qi; Huang, Xiang-Yu; Xing, Xin; Yu, Ru-Qing; Li, Zhi; Li, Zu-Bing

    2016-02-01

    Lysophosphatidic acid (LPA) is an efficient, bioactive phospholipid involved in various biological processes. In this study, LPA-induced connective tissue growth factor (CTGF/CCN2) expression and the underlying mechanisms were investigated using the MC3T3-E1 cell line. The MC3T3-E1 cells were stimulated with an inhibitor of LPA receptors, an activator and inhibitor of protein kinase C (PKC) and protein kinase A (PKA) for indicated periods of time. RT-qPCR and western blot analyses were used to measure the expression levels of CCN2. Immunofluorescence staining was used to observe the translocation of PKC. The mRNA expression level of CCN2 was increased following stimulation of the cells with LPA; LPA transiently induced the mRNA expression of CCN2; maximum expression levels were observed 2 h following stimulation with LPA. This increase was accompanied by CCN2 protein synthesis. LPA receptor1/3 was inhibited by Ki16425, a specific inhibitor of LPA1/3; as a result, the LPA-induced increase in CCN2 expression was abrogated. LPA also induced the membrane translocation of PKC and enhanced PKC activity in the osteoblasts. Pre-treatment of the osteoblasts with staurosporine prevented the increase in CCN2 expression by induced by LPA, and the activation of PKC by phorbol 12-myristate 13-acetate (PMA) enhanced CCN2 expression, indicating that the PKC pathway is involved in the LPA-induced increase in CCN2 expression. The interference of PKA signaling also led to the induction of CCN2 expresion by LPA. These data indicate that LPA increases CCN2 expression through the activation of PKC and PKA. Thus, the regulatory functions of the PKC and PKA pathways are implicated in the LPA-induced increase in CCN2 expression.

  5. Lysophosphatidic acid stimulates cell migration of satellite cells. A role for the sphingosine kinase/sphingosine 1-phosphate axis.

    PubMed

    Cencetti, Francesca; Bruno, Gennaro; Blescia, Sabrina; Bernacchioni, Caterina; Bruni, Paola; Donati, Chiara

    2014-10-01

    Regulation of the motility of skeletal muscle precursor cells, such as satellite cells, is critically important for their proper recruitment at the site of tissue damage, and ultimately for its correct repair. Here we show that lysophosphatidic acid (LPA), which is well-recognized as a powerful bioactive agent, strongly stimulates cell migration of activated murine satellite cells. The biological effect exerted by LPA was found to be induced via activation of LPA1 and LPA3 , being abolished by cell treatment with the antagonist Ki16425, and severely impaired by siRNA-mediated down-regulation of the two receptor isoforms. In contrast, silencing of LPA2 potentiated the stimulation of cell motility by LPA, suggesting that it is negatively coupled to cell migration. Pharmacological inhibition of both sphingosine kinase (SK) isoforms using VPC96047, or the selective blocking of SK1 using VPC96091, abolished cell responsiveness to LPA; in agreement, gene silencing of SK1 or SK2 significantly reduced the biological effect of LPA. Moreover, the LPA-dependent stimulation of cell chemotaxis was found to be impaired by down-regulation of the sphingosine 1-phosphate (S1P) receptors S1P1 or S1P4 by specific siRNAs. In summary, the results obtained support the notion that the sphingosine kinase/sphingosine 1-phosphate (SK/S1P) axis is critically involved in the mechanism by which LPA elicits its pro-migratory action. This study provides compelling new information on the regulatory mechanisms of satellite cell motility, and reinforces the view that the SK/S1P signaling pathway plays a crucial role in the control of skeletal muscle precursor cell biology. © 2014 FEBS.

  6. Autotaxin and lysophosphatidic acid1 receptor-mediated demyelination of dorsal root fibers by sciatic nerve injury and intrathecal lysophosphatidylcholine

    PubMed Central

    2010-01-01

    Background Although neuropathic pain is frequently observed in demyelinating diseases such as Guillain-Barré syndrome and multiple sclerosis, the molecular basis for the relationship between demyelination and neuropathic pain behaviors is poorly understood. Previously, we found that lysophosphatidic acid receptor (LPA1) signaling initiates sciatic nerve injury-induced neuropathic pain and demyelination. Results In the present study, we have demonstrated that sciatic nerve injury induces marked demyelination accompanied by myelin-associated glycoprotein (MAG) down-regulation and damage of Schwann cell partitioning of C-fiber-containing Remak bundles in the sciatic nerve and dorsal root, but not in the spinal nerve. Demyelination, MAG down-regulation and Remak bundle damage in the dorsal root were abolished in LPA1 receptor-deficient (Lpar1-/-) mice, but these alterations were not observed in sciatic nerve. However, LPA-induced demyelination in ex vivo experiments was observed in the sciatic nerve, spinal nerve and dorsal root, all which express LPA1 transcript and protein. Nerve injury-induced dorsal root demyelination was markedly attenuated in mice heterozygous for autotaxin (atx+/-), which converts lysophosphatidylcholine (LPC) to LPA. Although the addition of LPC to ex vivo cultures of dorsal root fibers in the presence of recombinant ATX caused potent demyelination, it had no significant effect in the absence of ATX. On the other hand, intrathecal injection of LPC caused potent dorsal root demyelination, which was markedly attenuated or abolished in atx+/- or Lpar1-/- mice. Conclusions These results suggest that LPA, which is converted from LPC by ATX, activates LPA1 receptors and induces dorsal root demyelination following nerve injury, which causes neuropathic pain. PMID:21062487

  7. Absence of the lysophosphatidic acid receptor LPA1 results in abnormal bone development and decreased bone mass☆,☆☆

    PubMed Central

    Gennero, Isabelle; Laurencin-Dalicieux, Sara; Conte-Auriol, Françoise; Briand-Mésange, Fabienne; Laurencin, Danielle; Rue, Jackie; Beton, Nicolas; Malet, Nicole; Mus, Marianne; Tokumura, Akira; Bourin, Philippe; Vico, Laurence; Brunel, Gérard; Oreffo, Richard O. C.; Chun, Jerold; Salles, Jean Pierre

    2013-01-01

    Lysophosphatidic acid (LPA) is a lipid mediator that acts in paracrine systems via interaction with a subset of G protein-coupled receptors (GPCRs). LPA promotes cell growth and differentiation, and has been shown to be implicated in a variety of developmental and pathophysiological processes. At least 6 LPA GPCRs have been identified to date: LPA1–LPA6. Several studies have suggested that local production of LPA by tissues and cells contributes to paracrine regulation, and a complex interplay between LPA and its receptors, LPA1 and LPA4, is believed to be involved in the regulation of bone cell activity. In particular, LPA1may activate both osteoblasts and osteoclasts. However, its role has not as yet been examined with regard to the overall status of bone in vivo. We attempted to clarify this role by defining the bone phenotype of LPA1(−/−) mice. These mice demonstrated significant bone defects and low bone mass, indicating that LPA1 plays an important role in osteogenesis. The LPA1(−/−) mice also presented growth and sternal and costal abnormalities, which highlights the specific roles of LPA1 during bone development. Microcomputed tomography and histological analysis demonstrated osteoporosis in the trabecular and cortical bone of LPA1(−/−) mice. Finally, bone marrow mesenchymal progenitors from these mice displayed decreased osteoblastic differentiation. These results suggest that LPA1 strongly influences bone development both qualitatively and quantitatively and that, in vivo, its absence results in decreased osteogenesis with no clear modification of osteoclasis. They open perspectives for a better understanding of the role of the LPA/LPA1 paracrine pathway in bone pathophysiology. PMID:21569876

  8. Absence of the lysophosphatidic acid receptor LPA1 results in abnormal bone development and decreased bone mass.

    PubMed

    Gennero, Isabelle; Laurencin-Dalicieux, Sara; Conte-Auriol, Françoise; Briand-Mésange, Fabienne; Laurencin, Danielle; Rue, Jackie; Beton, Nicolas; Malet, Nicole; Mus, Marianne; Tokumura, Akira; Bourin, Philippe; Vico, Laurence; Brunel, Gérard; Oreffo, Richard O C; Chun, Jerold; Salles, Jean Pierre

    2011-09-01

    Lysophosphatidic acid (LPA) is a lipid mediator that acts in paracrine systems via interaction with a subset of G protein-coupled receptors (GPCRs). LPA promotes cell growth and differentiation, and has been shown to be implicated in a variety of developmental and pathophysiological processes. At least 6 LPA GPCRs have been identified to date: LPA1-LPA6. Several studies have suggested that local production of LPA by tissues and cells contributes to paracrine regulation, and a complex interplay between LPA and its receptors, LPA1 and LPA4, is believed to be involved in the regulation of bone cell activity. In particular, LPA1 may activate both osteoblasts and osteoclasts. However, its role has not as yet been examined with regard to the overall status of bone in vivo. We attempted to clarify this role by defining the bone phenotype of LPA1((-/-)) mice. These mice demonstrated significant bone defects and low bone mass, indicating that LPA1 plays an important role in osteogenesis. The LPA1((-/-)) mice also presented growth and sternal and costal abnormalities, which highlights the specific roles of LPA1 during bone development. Microcomputed tomography and histological analysis demonstrated osteoporosis in the trabecular and cortical bone of LPA1((-/-)) mice. Finally, bone marrow mesenchymal progenitors from these mice displayed decreased osteoblastic differentiation. These results suggest that LPA1 strongly influences bone development both qualitatively and quantitatively and that, in vivo, its absence results in decreased osteogenesis with no clear modification of osteoclasis. They open perspectives for a better understanding of the role of the LPA/LPA1 paracrine pathway in bone pathophysiology. Copyright © 2011 Elsevier Inc. All rights reserved.

  9. Lysophosphatidic acid-induced ADAM12 expression mediates human adipose tissue-derived mesenchymal stem cell-stimulated tumor growth.

    PubMed

    Do, Eun Kyoung; Kim, Young Mi; Heo, Soon Chul; Kwon, Yang Woo; Shin, Sang Hun; Suh, Dong-Soo; Kim, Ki-Hyung; Yoon, Man-Soo; Kim, Jae Ho

    2012-11-01

    Lysophosphatidic acid (LPA) is involved in mesenchymal stem cell-stimulated tumor growth in vivo. However, the molecular mechanism by which mesenchymal stem cells promote tumorigenesis remains elusive. In the present study, we demonstrate that conditioned medium from A549 human lung adenocarcinoma cells (A549 CM) induced the expression of ADAM12, a disintegrin and metalloproteases family member, in human adipose tissue-derived mesenchymal stem cells (hASCs). A549 CM-stimulated ADAM12 expression was abrogated by pretreatment of hASCs with the LPA receptor 1 inhibitor Ki16425 or by small interfering RNA-mediated silencing of LPA receptor 1, suggesting a key role for the LPA-LPA receptor 1 signaling axis in A549 CM-stimulated ADAM12 expression. Silencing of ADAM12 expression using small interfering RNA or short hairpin RNA abrogated LPA-induced expression of both α-smooth muscle actin, a marker of carcinoma-associated fibroblasts, and ADAM12 in hASCs. Using a xenograft transplantation model of A549 cells, we demonstrated that silencing of ADAM12 inhibited the hASC-stimulated in vivo growth of A549 xenograft tumors and the differentiation of transplanted hASCs to α-smooth muscle actin-positive carcinoma-associated fibroblasts. LPA-conditioned medium from hASCs induced the adhesion of A549 cells and silencing of ADAM12 inhibited LPA-induced expression of extracellular matrix proteins, periostin and βig-h3, in hASCs and LPA-conditioned medium-stimulated adhesion of A549 cells. These results suggest a pivotal role for LPA-stimulated ADAM12 expression in tumor growth and the differentiation of hASCs to carcinoma-associated fibroblasts expressing α-smooth muscle actin, periostin, and βig-h3.

  10. Lysophosphatidic Acid Receptor Type 1 (LPA1) Plays a Functional Role in Osteoclast Differentiation and Bone Resorption Activity*

    PubMed Central

    David, Marion; Machuca-Gayet, Irma; Kikuta, Junichi; Ottewell, Penelope; Mima, Fuka; Leblanc, Raphael; Bonnelye, Edith; Ribeiro, Johnny; Holen, Ingunn; Vales, Rùben Lopez; Jurdic, Pierre; Chun, Jerold; Clézardin, Philippe; Ishii, Masaru; Peyruchaud, Olivier

    2014-01-01

    Lysophosphatidic acid (LPA) is a natural bioactive lipid that acts through six different G protein-coupled receptors (LPA1–6) with pleiotropic activities on multiple cell types. We have previously demonstrated that LPA is necessary for successful in vitro osteoclastogenesis of bone marrow cells. Bone cells controlling bone remodeling (i.e. osteoblasts, osteoclasts, and osteocytes) express LPA1, but delineating the role of this receptor in bone remodeling is still pending. Despite Lpar1−/− mice displaying a low bone mass phenotype, we demonstrated that bone marrow cell-induced osteoclastogenesis was reduced in Lpar1−/− mice but not in Lpar2−/− and Lpar3−/− animals. Expression of LPA1 was up-regulated during osteoclastogenesis, and LPA1 antagonists (Ki16425, Debio0719, and VPC12249) inhibited osteoclast differentiation. Blocking LPA1 activity with Ki16425 inhibited expression of nuclear factor of activated T-cell cytoplasmic 1 (NFATc1) and dendritic cell-specific transmembrane protein and interfered with the fusion but not the proliferation of osteoclast precursors. Similar to wild type osteoclasts treated with Ki16425, mature Lpar1−/− osteoclasts had reduced podosome belt and sealing zone resulting in reduced mineralized matrix resorption. Additionally, LPA1 expression markedly increased in the bone of ovariectomized mice, which was blocked by bisphosphonate treatment. Conversely, systemic treatment with Debio0719 prevented ovariectomy-induced cancellous bone loss. Moreover, intravital multiphoton microscopy revealed that Debio0719 reduced the retention of CX3CR1-EGFP+ osteoclast precursors in bone by increasing their mobility in the bone marrow cavity. Overall, our results demonstrate that LPA1 is essential for in vitro and in vivo osteoclast activities. Therefore, LPA1 emerges as a new target for the treatment of diseases associated with excess bone loss. PMID:24429286

  11. Deficiency or inhibition of lysophosphatidic acid receptor 1 protects against hyperoxia-induced lung injury in neonatal rats

    PubMed Central

    Chen, Xueyu; Walther, Frans J; van Boxtel, Ruben; Laghmani, El Houari; Sengers, Rozemarijn M A; Folkerts, Gert; DeRuiter, Marco C.; Cuppen, Edwin; Wagenaar, Gerry T M

    2015-01-01

    Aim Blocking of lysophosphatidic acid (LPA) receptor (LPAR) 1 may be a novel therapeutic option for bronchopulmonary dysplasia (BPD) by preventing the LPAR1-mediated adverse effects of its ligand (LPA), consisting of lung inflammation, pulmonary arterial hypertension (PAH) and fibrosis. Methods In Wistar rats with experimental BPD, induced by continuous exposure to 100% oxygen for 10 days, we determined the beneficial effects of LPAR1 deficiency in neonatal rats with a missense mutation in cytoplasmic helix 8 of LPAR1 and of LPAR1 and -3 blocking with Ki16425. Parameters investigated included survival, lung and heart histopathology, fibrin and collagen deposition, vascular leakage, and differential mRNA expression in the lungs of key genes involved in LPA signalling and BPD pathogenesis. Results LPAR1 mutant rats were protected against experimental BPD and mortality with reduced alveolar septal thickness, lung inflammation (reduced influx of macrophages and neutrophils, and CINC1 expression), and collagen III deposition. However, LPAR1 mutant rats were not protected against alveolar enlargement, increased medial wall thickness of small arterioles, fibrin deposition, and vascular alveolar leakage. Treatment of experimental BPD with Ki16425 confirmed the data observed in LPAR1 mutant rats, but did not reduce the pulmonary influx of neutrophils, CINC1 expression, and mortality in rats with experimental BPD. In addition, Ki16425 treatment protected against PAH and right ventricular hypertrophy. Conclusion LPAR1 deficiency attenuates pulmonary injury by reducing pulmonary inflammation and fibrosis, thereby reducing mortality, but does not affect alveolar and vascular development and, unlike Ki16425 treatment, does not prevent PAH in neonatal rats with experimental BPD. PMID:26495902

  12. Study of lysophosphatidic acid receptors (LPARs) in buffalo uterus demonstrated upregulation of LPAR1 and LPAR6 in early pregnancy.

    PubMed

    Sadam, Abdul; Parida, Subhashree; Padol, Amol R; Verma, Ankita D; Baba, Naseer Ahmad; Khuman, Wanta M; Srivastava, Vivek; Panigrahi, Manjit; Singh, Thakur Uttam; Sarkar, Souvendra Nath

    2017-09-01

    Lysophosphatidic acid (LPA) is an important factor involved in embryo implantation and pregnancy establishment in humans and domestic livestock. LPA exerts its action through six G-protein-coupled receptors (LPA1-LPA6). We investigated the types of LPA receptors expressed in buffalo uterus and also their differential expression in the nonpregnant, and early-pregnant endometrium. The nonpregnant, and early-pregnant (<42 days) uteri were collected from the local slaughterhouse. RT-PCR experiments detected mRNAs of all the six LPA receptors (LPAR1-LPAR6) in both nonpregnant, and early-pregnant endometrial tissues. Their comparative profiling by real-time PCR revealed that the early pregnant endometrium expressed more mRNAs of LPAR1 and LPAR6. All the mRNA fragments were sequenced and submitted to Genbank, NCBI. Western blot studies also showed a similar expression pattern of these two receptor proteins, including higher expression of both LPA1 and LPA6 proteins during early pregnancy. And between these two receptors, LPA6 upregulation was more pronounced than LPA1. In immunohistochemistry, these receptors were found to be localized in the endometrial glandular epithelial cells of both types of uterus. Level of LPA was also higher in early pregnant endometrial tissues. In summary, our study demonstrated expression of all the six LPAR mRNAs in buffalo uterus, wherein the early-pregnant uterus did express comparatively higher mRNA as well as protein of LPA1 and LPA6, indicating their role in pregnancy. The more pronounced expression of LPA6 possibly indicates its greater contribution to mediating LPA signaling in early pregnancy (29-42 days) of buffalo. Copyright © 2017 Elsevier Inc. All rights reserved.

  13. Identification of a Chlamydomonas plastidial 2-lysophosphatidic acid acyltransferase and its use to engineer microalgae with increased oil content.

    PubMed

    Yamaoka, Yasuyo; Achard, Dorine; Jang, Sunghoon; Legéret, Bertrand; Kamisuki, Shogo; Ko, Donghwi; Schulz-Raffelt, Miriam; Kim, Yeongho; Song, Won-Yong; Nishida, Ikuo; Li-Beisson, Yonghua; Lee, Youngsook

    2016-11-01

    Despite a strong interest in microalgal oil production, our understanding of the biosynthetic pathways that produce algal lipids and the genes involved in the biosynthetic processes remains incomplete. Here, we report that Chlamydomonas reinhardtii Cre09.g398289 encodes a plastid-targeted 2-lysophosphatidic acid acyltransferase (CrLPAAT1) that acylates the sn-2 position of a 2-lysophosphatidic acid to form phosphatidic acid, the first common precursor of membrane and storage lipids. In vitro enzyme assays showed that CrLPAAT1 prefers 16:0-CoA to 18:1-CoA as an acyl donor. Fluorescent protein-tagged CrLPAAT1 was localized to the plastid membrane in C. reinhardtii cells. Furthermore, expression of CrLPAAT1 in plastids led to a > 20% increase in oil content under nitrogen-deficient conditions. Taken together, these results demonstrate that CrLPAAT1 is an authentic plastid-targeted LPAAT in C. reinhardtii, and that it may be used as a molecular tool to genetically increase oil content in microalgae. © 2016 The Authors. Plant Biotechnology Journal published by Society for Experimental Biology and The Association of Applied Biologists and John Wiley & Sons Ltd.

  14. Endosomal H2O2 production leads to localized cysteine sulfenic acid formation on proteins during lysophosphatidic acid-mediated cell signaling

    PubMed Central

    Klomsiri, Chananat; Rogers, LeAnn C.; Soito, Laura; McCauley, Anita K.; King, S. Bruce; Nelson, Kimberly J.; Poole, Leslie B.; Daniel, Larry W.

    2014-01-01

    Lysophosphatidic acid (LPA) is a growth factor for many cells including prostate and ovarian cancer-derived cell lines. LPA stimulates H2O2 production which is required for growth. However, there are significant gaps in our understanding of the spatial and temporal regulation of H2O2-dependent signaling and the way in which signals are transmitted following receptor activation. Herein, we describe the use of two reagents, DCP-Bio1 and DCP-Rho1, to evaluate the localization of active protein oxidation after LPA stimulation by detection of nascent protein sulfenic acids. We found that LPA stimulation causes internalization of LPA receptors into early endosomes that contain NADPH oxidase components and are sites of H2O2 generation. DCP-Rho1 allowed visualization of sulfenic acid formation, indicative of active protein oxidation, which was stimulated by LPA and decreased by an LPA receptor antagonist. Protein oxidation sites colocalized with LPAR1 and the endosomal marker EEA1. Concurrent with the generation of these redox signaling-active endosomes (redoxosomes) is the H2O2- and NADPH oxidase-dependent oxidation of Akt2 and PTP1B detected using DCP-Bio1. These new approaches therefore enable detection of active, H2O2-dependent protein oxidation linked to cell signaling processes. DCP-Rho1 may be a particularly useful protein oxidation imaging agent enabling spatial resolution due to the transient nature of the sulfenic acid intermediate it detects. PMID:24657741

  15. Heart-type fatty-acid-binding protein (FABP3) is a lysophosphatidic acid-binding protein in human coronary artery endothelial cells.

    PubMed

    Tsukahara, Ryoko; Haniu, Hisao; Matsuda, Yoshikazu; Tsukahara, Tamotsu

    2014-01-01

    Fatty-acid-binding protein 3, muscle and heart (FABP3), also known as heart-type FABP, is a member of the family of intracellular lipid-binding proteins. It is a small cytoplasmic protein with a molecular mass of about 15 kDa. FABPs are known to be carrier proteins for transporting fatty acids and other lipophilic substances from the cytoplasm to the nucleus, where these lipids are released to a group of nuclear receptors such as peroxisome proliferator-activated receptors (PPARs). In this study, using lysophosphatidic acid (LPA)-coated agarose beads, we have identified FABP3 as an LPA carrier protein in human coronary artery endothelial cells (HCAECs). Administration of LPA to HCAECs resulted in a dose-dependent increase in PPARγ activation. Furthermore, the LPA-induced PPARγ activation was abolished when the FABP3 expression was reduced using small interfering RNA (siRNA). We further show that the nuclear fraction of control HCAECs contained a significant amount of exogenously added LPA, whereas FABP3 siRNA-transfected HCAECs had a decreased level of LPA in the nucleus. Taken together, these results suggest that FABP3 governs the transcriptional activities of LPA by targeting them to cognate PPARγ in the nucleus.

  16. Heart-type fatty-acid-binding protein (FABP3) is a lysophosphatidic acid-binding protein in human coronary artery endothelial cells

    PubMed Central

    Tsukahara, Ryoko; Haniu, Hisao; Matsuda, Yoshikazu; Tsukahara, Tamotsu

    2014-01-01

    Fatty-acid-binding protein 3, muscle and heart (FABP3), also known as heart-type FABP, is a member of the family of intracellular lipid-binding proteins. It is a small cytoplasmic protein with a molecular mass of about 15 kDa. FABPs are known to be carrier proteins for transporting fatty acids and other lipophilic substances from the cytoplasm to the nucleus, where these lipids are released to a group of nuclear receptors such as peroxisome proliferator-activated receptors (PPARs). In this study, using lysophosphatidic acid (LPA)-coated agarose beads, we have identified FABP3 as an LPA carrier protein in human coronary artery endothelial cells (HCAECs). Administration of LPA to HCAECs resulted in a dose-dependent increase in PPARγ activation. Furthermore, the LPA-induced PPARγ activation was abolished when the FABP3 expression was reduced using small interfering RNA (siRNA). We further show that the nuclear fraction of control HCAECs contained a significant amount of exogenously added LPA, whereas FABP3 siRNA-transfected HCAECs had a decreased level of LPA in the nucleus. Taken together, these results suggest that FABP3 governs the transcriptional activities of LPA by targeting them to cognate PPARγ in the nucleus. PMID:25426414

  17. Cancer Cell Expression of Autotaxin Controls Bone Metastasis Formation in Mouse through Lysophosphatidic Acid-Dependent Activation of Osteoclasts

    PubMed Central

    David, Marion; Wannecq, Estelle; Descotes, Françoise; Jansen, Silvia; Deux, Blandine; Ribeiro, Johnny; Serre, Claire-Marie; Grès, Sandra; Bendriss-Vermare, Nathalie; Bollen, Mathieu; Saez, Simone; Aoki, Junken; Saulnier-Blache, Jean-Sébastien; Clézardin, Philippe; Peyruchaud, Olivier

    2010-01-01

    Background Bone metastases are highly frequent complications of breast cancers. Current bone metastasis treatments using powerful anti-resorbtive agents are only palliative indicating that factors independent of bone resorption control bone metastasis progression. Autotaxin (ATX/NPP2) is a secreted protein with both oncogenic and pro-metastatic properties. Through its lysosphospholipase D (lysoPLD) activity, ATX controls the level of lysophosphatidic acid (LPA) in the blood. Platelet-derived LPA promotes the progression of osteolytic bone metastases of breast cancer cells. We asked whether ATX was involved in the bone metastasis process. We characterized the role of ATX in osteolytic bone metastasis formation by using genetically modified breast cancer cells exploited on different osteolytic bone metastasis mouse models. Methodology/Principal Findings Intravenous injection of human breast cancer MDA-B02 cells with forced expression of ATX (MDA-B02/ATX) to inmmunodeficiency BALB/C nude mice enhanced osteolytic bone metastasis formation, as judged by increased bone loss, tumor burden, and a higher number of active osteoclasts at the metastatic site. Mouse breast cancer 4T1 cells induced the formation of osteolytic bone metastases after intracardiac injection in immunocompetent BALB/C mice. These cells expressed active ATX and silencing ATX expression inhibited the extent of osteolytic bone lesions and decreased the number of active osteoclasts at the bone metastatic site. In vitro, osteoclast differentiation was enhanced in presence of MDA-B02/ATX cell conditioned media or recombinant autotaxin that was blocked by the autotaxin inhibitor vpc8a202. In vitro, addition of LPA to active charcoal-treated serum restored the capacity of the serum to support RANK-L/MCSF-induced osteoclastogenesis. Conclusion/Significance Expression of autotaxin by cancer cells controls osteolytic bone metastasis formation. This work demonstrates a new role for LPA as a factor that stimulates

  18. Cancer cell expression of autotaxin controls bone metastasis formation in mouse through lysophosphatidic acid-dependent activation of osteoclasts.

    PubMed

    David, Marion; Wannecq, Estelle; Descotes, Françoise; Jansen, Silvia; Deux, Blandine; Ribeiro, Johnny; Serre, Claire-Marie; Grès, Sandra; Bendriss-Vermare, Nathalie; Bollen, Mathieu; Saez, Simone; Aoki, Junken; Saulnier-Blache, Jean-Sébastien; Clézardin, Philippe; Peyruchaud, Olivier

    2010-03-17

    Bone metastases are highly frequent complications of breast cancers. Current bone metastasis treatments using powerful anti-resorptive agents are only palliative indicating that factors independent of bone resorption control bone metastasis progression. Autotaxin (ATX/NPP2) is a secreted protein with both oncogenic and pro-metastatic properties. Through its lysosphospholipase D (lysoPLD) activity, ATX controls the level of lysophosphatidic acid (LPA) in the blood. Platelet-derived LPA promotes the progression of osteolytic bone metastases of breast cancer cells. We asked whether ATX was involved in the bone metastasis process. We characterized the role of ATX in osteolytic bone metastasis formation by using genetically modified breast cancer cells exploited on different osteolytic bone metastasis mouse models. Intravenous injection of human breast cancer MDA-B02 cells with forced expression of ATX (MDA-B02/ATX) to immunodeficiency BALB/C nude mice enhanced osteolytic bone metastasis formation, as judged by increased bone loss, tumor burden, and a higher number of active osteoclasts at the metastatic site. Mouse breast cancer 4T1 cells induced the formation of osteolytic bone metastases after intracardiac injection in immunocompetent BALB/C mice. These cells expressed active ATX and silencing ATX expression inhibited the extent of osteolytic bone lesions and decreased the number of active osteoclasts at the bone metastatic site. In vitro, osteoclast differentiation was enhanced in presence of MDA-B02/ATX cell conditioned media or recombinant autotaxin that was blocked by the autotaxin inhibitor vpc8a202. In vitro, addition of LPA to active charcoal-treated serum restored the capacity of the serum to support RANK-L/MCSF-induced osteoclastogenesis. Expression of autotaxin by cancer cells controls osteolytic bone metastasis formation. This work demonstrates a new role for LPA as a factor that stimulates directly cancer growth and metastasis, and osteoclast

  19. Lysophosphatidic acid receptor 4 signaling potentially modulates malignant behavior in human head and neck squamous cell carcinoma cells

    PubMed Central

    MATAYOSHI, SEN; CHIBA, SHUNMEI; LIN, YANFUI; ARAKAKI, KAZUNARI; MATSUMOTO, HIROFUMI; NAKANISHI, TAKAYA; SUZUKI, MIKIO; KATO, SEIYA

    2013-01-01

    Head and neck squamous cell carcinoma (HNSCC) is the sixth most common non-skin cancer worldwide. Despite improvement in therapeutic strategies, the prognosis of advanced HNSCC remains poor. The extacellular lipid mediators known as lysophosphatidic acids (LPAs) have been implicated in tumorigenesis of HNSCC. LPAs activate G-protein-coupled receptors not only in the endothelial differentiation gene (Edg) family (LPA1, LPA2, LPA3) but also in the phylogenetically distant non-Edg family (LPA4, LPA5, LPA6). The distinct roles of these receptor isoforms in HNSCC tumorigenesis have not been clarified. In the present study, we investigated the effect of ectopic expression of LPA4 in SQ-20B, an HNSCC cell line, expressing a trivial level of endogenous LPA4. LPA (18:1) stimulated proliferation of SQ-20B cells, but did not affect proliferation of HEp-2, an SCC cell line expressing higher levels of LPA4, comparable to those of with LPA1. LPA-stimulated proliferation of SQ-20B cells was attenuated by Ki16425 and Rac1 inhibitor, but not by Y-27632. Infection with doxycycline-regulatable adenovirus vector expressing green fluorescent protein-tagged LPA4 (AdvLPA4G) abolished LPA-stimulated proliferation in SQ-20B cells with the accumulation of G2/M-phasic cells. Ectopic LPA4 induction further downregulated proliferation of Ki16425-treated SQ-20B cells, of which downregulation was partially recovered by LPA. Ectopic LPA4 induction also downregulated proliferation of Rac1 inhibitor-treated SQ-20B cells, however, LPA no longer recovered it. Finally, LPA-induced cell motility was suppressed by ectopic LPA4 expression as well as by Ki16425, Rac1 inhibitor or Y-27632. Our data suggest that LPA4 signaling potentially modulates malignant behavior of SQ-20B cells. LPA signaling, which is mediated by both Edg and non-Edg receptors, may be a determinant of malignant behavior of HNSCC and could therefore be a promising therapeutic target. PMID:23467751

  20. Lysophosphatidic acid enhanced the angiogenic capability of human chondrocytes by regulating Gi/NF-kB-dependent angiogenic factor expression.

    PubMed

    Chuang, Yi-Wen; Chang, Wen-Ming; Chen, Kai-Hua; Hong, Chang-Zern; Chang, Pey-Jium; Hsu, Hung-Chih

    2014-01-01

    Lysophosphatidic acid (LPA) has been found to mediate myeloid differentiation, stimulate osteogenesis, alter cell proliferation and migration, and inhibit apoptosis in chondrocytes. The effect of LPA on the angiogenic capability of chondrocytes is not clear. This study aimed to investigate its effect on the angiogenic capability of human chondrocytes and the underlying mechanism of these effects. Human chondrocyte cell line, CHON-001, commercialized human chondrocytes (HC) derived from normal human articular cartilage, and human vascular endothelial cells (HUVECs) were used as cell models in this study. The angiogenic capability of chondrocytes was determined by capillary tube formation, monolayer permeability, cell migration, and cell proliferation. An angiogenesis protein array kit was used to evaluate the secretion of angiogenic factors in conditioned medium. Angiogenin, insulin-like growth factor-binding protein 1 (IGFBP-1), interleukin (IL)-8, monocyte chemoattractant protein-1 (MCP-1), matrix metalloproteinase (MMP)-9, and vascular endothelial growth factor (VEGF) mRNA and protein expressions were evaluated by Q-RT-PCR and EIA, respectively. LPA receptor (LPAR) expression was determined by RT-PCR. Signaling pathways were clarified using inhibitors, Western blot analysis, and reporter assays. The LPA treatment promoted the angiogenic capability of CHON-001 cells and HC, resulting in enhanced HUVEC capillary tube formation, monolayer permeability, migration, and cell growth. Angiogenin, IGFBP-1, IL-8, MCP-1, MMP-9, and VEGF mRNA and protein expressions were significantly enhanced in LPA-treated chondrocytes. LPA2, 3, 4 and 6 were expressed in CHON-001 and HC cells. Pretreatment with the Gi/o type G protein inhibitor, pertussis toxin (PTX), and the NF-kB inhibitor, PDTC, significantly inhibited LPA-induced angiogenin, IGFBP-1, IL-8, MCP-1, MMP-9, and VEGF expressions in chondrocytes. The PTX pretreatment also inhibited LPA-mediated NF-kB activation, suggesting

  1. Quantitation of phosphatidic acid and lysophosphatidic acid molecular species using hydrophilic interaction liquid chromatography coupled to electrospray ionization high resolution mass spectrometry.

    PubMed

    Triebl, Alexander; Trötzmüller, Martin; Eberl, Anita; Hanel, Pia; Hartler, Jürgen; Köfeler, Harald C

    2014-06-20

    A method for a highly selective and sensitive identification and quantitation of lysophosphatidic acid (LPA) and phosphatidic acid (PA) molecular species was developed using hydrophilic interaction liquid chromatography (HILIC) followed by negative-ion electrospray ionization high resolution mass spectrometry. Different extraction methods for the polar LPA and PA species were compared and a modified Bligh & Dyer extraction by addition of 0.1M hydrochloric acid resulted in a ≈1.2-fold increase of recovery for the 7 PA and a more than 15-fold increase for the 6 LPA molecular species of a commercially available natural mix compared to conventional Bligh & Dyer extraction. This modified Bligh & Dyer extraction did not show any artifacts resulting from hydrolysis of natural abundant phospholipids. The developed HILIC method is able to separate all PA and LPA species from major polar membrane lipid classes which might have suppressive effects on the minor abundant lipid classes of interest. The elemental compositions of intact lipid species are provided by the high mass resolution of 100,000 and high mass accuracy below 3ppm of the Orbitrap instrument. Additionally, tandem mass spectra were generated in a parallel data dependent acquisition mode in the linear ion trap to provide structural information at molecular level. Limits of quantitation were identified at 45fmol on column and the dynamic range reaches 20pmol on column, covering the range of natural abundance well. By applying the developed method to mouse brain it can be shown that phosphatidic acid contains less unsaturated fatty acids with PA 34:1 and PA 36:1 as the major species. In contrast, for LPA species a high content of polyunsaturated fatty acids (LPA 20:4 and LPA 22:6) was quantified. Copyright © 2014 Elsevier B.V. All rights reserved.

  2. Endosomal H2O2 production leads to localized cysteine sulfenic acid formation on proteins during lysophosphatidic acid-mediated cell signaling.

    PubMed

    Klomsiri, Chananat; Rogers, LeAnn C; Soito, Laura; McCauley, Anita K; King, S Bruce; Nelson, Kimberly J; Poole, Leslie B; Daniel, Larry W

    2014-06-01

    Lysophosphatidic acid (LPA) is a growth factor for many cells including prostate and ovarian cancer-derived cell lines. LPA stimulates H2O2 production which is required for growth. However, there are significant gaps in our understanding of the spatial and temporal regulation of H2O2-dependent signaling and the way in which signals are transmitted following receptor activation. Herein, we describe the use of two reagents, DCP-Bio1 and DCP-Rho1, to evaluate the localization of active protein oxidation after LPA stimulation by detection of nascent protein sulfenic acids. We found that LPA stimulation causes internalization of LPA receptors into early endosomes that contain NADPH oxidase components and are sites of H2O2 generation. DCP-Rho1 allowed visualization of sulfenic acid formation, indicative of active protein oxidation, which was stimulated by LPA and decreased by an LPA receptor antagonist. Protein oxidation sites colocalized with LPAR1 and the endosomal marker EEA1. Concurrent with the generation of these redox signaling-active endosomes (redoxosomes) is the H2O2- and NADPH oxidase-dependent oxidation of Akt2 and PTP1B detected using DCP-Bio1. These new approaches therefore enable detection of active, H2O2-dependent protein oxidation linked to cell signaling processes. DCP-Rho1 may be a particularly useful protein oxidation imaging agent enabling spatial resolution due to the transient nature of the sulfenic acid intermediate it detects. Copyright © 2014 Elsevier Inc. All rights reserved.

  3. Positive and Negative Cross-Talk between Lysophosphatidic Acid Receptor 1, Free Fatty Acid Receptor 4, and Epidermal Growth Factor Receptor in Human Prostate Cancer Cells.

    PubMed

    Hopkins, Mandi M; Liu, Ze; Meier, Kathryn E

    2016-10-01

    Lysophosphatidic acid (LPA) is a lipid mediator that mediates cellular effects via G protein-coupled receptors (GPCRs). Epidermal growth factor (EGF) is a peptide that acts via a receptor tyrosine kinase. LPA and EGF both induce proliferation of prostate cancer cells and can transactivate each other's receptors. The LPA receptor LPA1 is particularly important for LPA response in human prostate cancer cells. Previous work in our laboratory has demonstrated that free fatty acid 4 (FFA4), a GPCR activated by ω-3 fatty acids, inhibits responses to both LPA and EGF in these cells. One potential mechanism for the inhibition involves negative interactions between FFA4 and LPA1, thereby suppressing responses to EGF that require LPA1 In the current study, we examined the role of LPA1 in mediating EGF and FFA4 agonist responses in two human prostate cancer cell lines, DU145 and PC-3. The results show that an LPA1-selective antagonist inhibits proliferation and migration to both LPA and EGF. Knockdown of LPA1 expression, using silencing RNA, blocks responses to LPA and significantly inhibits responses to EGF. The partial response to EGF that is observed after LPA1 knockdown is not inhibited by FFA4 agonists. Finally, the role of arrestin-3, a GPCR-binding protein that mediates many actions of activated GPCRs, was tested. Knockdown of arrestin-3 completely inhibits responses to both LPA and EGF in prostate cancer cells. Taken together, these results suggest that LPA1 plays a critical role in EGF responses and that FFA4 agonists inhibit proliferation by suppressing positive cross-talk between LPA1 and the EGF receptor. Copyright © 2016 by The American Society for Pharmacology and Experimental Therapeutics.

  4. The case for the autotaxin – lysophosphatidic acid – lipid phosphate phosphase 3 (ATX/LPA/LPP3) signaling nexus in the development and complications of atherosclerosis

    PubMed Central

    Smyth, Susan S.; Mueller, Paul; Yang, Fanmuyi; Brandon, J. Anthony; Morris, Andrew J.

    2014-01-01

    The structurally simple glycero- and sphingo-phospholipids, lysophosphatidic acid (LPA) and sphingosine-1-phosphate (S1P), serve as important receptor-active mediators that influence blood and vascular cell function and are positioned to influence the events that contribute to the progression and complications of atherosclerosis. Growing evidence from preclinical, animal models has implicated LPA, LPA receptors, and key enzymes involved in LPA metabolism in pathophysiologic events that may underlie atherosclerotic vascular disease. These observations are supported by genetic analysis in humans implicating a lipid phosphate phosphatase as a novel risk factor for coronary artery disease. In this review we summarize current understanding of LPA production, metabolism and signaling as may be relevant for atherosclerotic and other vascular disease. PMID:24482375

  5. The phospholipase A2 activity of peroxiredoxin 6 modulates NADPH oxidase 2 activation via lysophosphatidic acid receptor signaling in the pulmonary endothelium and alveolar macrophages.

    PubMed

    Vázquez-Medina, José Pablo; Dodia, Chandra; Weng, Liwei; Mesaros, Clementina; Blair, Ian A; Feinstein, Sheldon I; Chatterjee, Shampa; Fisher, Aron B

    2016-08-01

    Peroxiredoxin 6 (Prdx6) is essential for activation of NADPH oxidase type 2 (NOX2) in pulmonary microvascular endothelial cells (PMVECs), alveolar macrophages (AMs), and polymorphonuclear leukocytes. Angiotensin II and phorbol ester increased superoxide/H2O2 generation in PMVECs, AMs, and isolated lungs from wild-type (WT) mice, but had much less effect on cells or lungs from Prdx6-null or Prdx6-D140A-knock-in mice that lack the phospholipase A2 activity (PLA2) of Prdx6; addition of either lysophosphatidylcholine (LPC) or lysophosphatidic acid (LPA) to cells restored their oxidant generation. The generation of LPC by PMVECs required Prdx6-PLA2 We propose that Prdx6-PLA2 modulates NOX2 activation by generation of LPC that is converted to LPA by the lysophospholipase D activity of autotaxin (ATX/lysoPLD). Inhibition of lysoPLD with HA130 (cells,10 μM; lungs, 20 μM; IC50, 29 nM) decreased agonist-induced oxidant generation. LPA stimulates pathways regulated by small GTPases through binding to G-protein-coupled LPA receptors (LPARs). The LPAR blocker Ki16425 (cells, 10 μM; lungs, 25 μM; Ki, 0.34 μM) or cellular knockdown of LPAR type 1 decreased oxidant generation and blocked translocation of rac1 to plasma membrane. Thus, Prdx6-PLA2 modulates NOX2 activation through generation of LPC for conversion to LPA; binding of LPA to LPAR1 signals rac activation.-Vázquez-Medina, J. P., Dodia, C., Weng, L., Mesaros, C., Blair, I. A., Feinstein, S. I., Chatterjee, S., Fisher, A. B. The phospholipase A2 activity of peroxiredoxin 6 modulates NADPH oxidase 2 activation via lysophosphatidic acid receptor signaling in the pulmonary endothelium and alveolar macrophages. © FASEB.

  6. Structural requirements for charged lipid molecules to directly increase or suppress K+ channel activity in smooth muscle cells. Effects of fatty acids, lysophosphatidate, acyl coenzyme A and sphingosine

    PubMed Central

    1994-01-01

    We determined the structural features necessary for fatty acids to exert their action on K+ channels of gastric smooth muscle cells. Examination of the effects of a variety of synthetic and naturally occurring lipid compounds on K+ channel activity in cell-attached and excised membrane patches revealed that negatively charged analogs of medium to long chain fatty acids (but not short chain analogs) as well as certain other negatively charged lipids activate the channels. In contrast, positively charged, medium to long chain analogs suppress activity, and neutral analogs are without effect. The key requirements for effective compounds seem to be a sufficiently hydrophobic domain and the presence of a charged group. Furthermore, those negatively charged compounds unable to "flip" across the bilayer are effective only when applied at the cytosolic surface of the membrane, suggesting that the site of fatty acid action is also located there. Finally, because some of the effective compounds, for example, the fatty acids themselves, lysophosphatidate, acyl Coenzyme A, and sphingosine, are naturally occurring substances and can be liberated by agonist- activated or metabolic enzymes, they may act as second messengers targeting ion channels. PMID:8195783

  7. The effects of aspirin and fish oil consumption on lysophosphatidylcholines and lysophosphatidic acids and their correlates with platelet aggregation in adults with diabetes mellitus.

    PubMed

    Abdolahi, Amir; Georas, Steve N; Brenna, J Thomas; Cai, Xueya; Thevenet-Morrison, Kelly; Phipps, Richard P; Lawrence, Peter; Mousa, Shaker A; Block, Robert C

    2014-01-01

    Many diabetics are insensitive to aspirin's platelet anti-aggregation effects. The influence of co-administration of aspirin and fish oil (FO) on plasma lysophospholipids in subjects with diabetes is poorly characterized. Thirty adults with type 2 diabetes mellitus were treated with aspirin (81mg/day) for seven days, then with FO (4g/day) for 28 days, then in combination for another seven days. Lysophospholipids and platelet measures were determined after acute (4h) and chronic (7 days) ingestion of aspirin, FO, or both in combination. FO ingestion reduced all lysophosphatidic acid (LPA) concentrations, while EPA (20:5n-3) and DHA (22:6n-3) lysophosphatidylcholine (LPC) concentrations significantly increased after FO alone and in combination with aspirin. In vitro arachidonic acid-induced platelet aggregation was most strongly correlated with palmitoleic (16:1) and oleic (18:1) LPA and LPC concentrations at all time points. The ingestion of these agents may reduce cardiovascular disease risk in diabetic adults, with a disrupted lipid milieu, via lysolipid mediated mechanisms. Copyright © 2013 Elsevier Ltd. All rights reserved.

  8. The effects of aspirin and fish oil consumption on lysophosphatidylcholines and lysophosphatidic acids and their correlates with platelet aggregation in adults with diabetes mellitus

    PubMed Central

    Abdolahi, Amir; Georas, Steve N; Brenna, J. Thomas; Cai, Xueya; Thevenet-Morrison, Kelly; Phipps, Richard P; Lawrence, Peter; Mousa, Shaker A; Block, Robert C

    2014-01-01

    Many diabetics are insensitive to aspirin's platelet anti-aggregation effects. The influence of co-administration of aspirin and fish oil (FO) on plasma lysophospholipids in subjects with diabetes is poorly characterized. Thirty adults with type 2 diabetes mellitus were treated with aspirin (81 mg/day) for seven days, then with FO (4 g/day) for 28 days, then in combination for another seven days. Lysophospholipids and platelet measures were determined after acute (4 hours) and chronic (7 days) ingestion of aspirin, FO, or both in combination. FO ingestion reduced all lysophosphatidic acid (LPA) concentrations, while EPA (20:5n-3) and DHA (22:6n-3) lysophosphatidylcholine (LPC) concentrations significantly increased after FO alone and in combination with aspirin. In vitro arachidonic acid-induced platelet aggregation was most strongly correlated with palmitoleic (16:1) and oleic (18:1) LPA and LPC concentrations at all time points. The ingestion of these agents may reduce cardiovascular disease risk in diabetic adults, with a disrupted lipid milieu, via lysolipid mediated mechanisms. PMID:24373610

  9. AM966, an Antagonist of Lysophosphatidic Acid Receptor 1, Increases Lung Microvascular Endothelial Permeability through Activation of Rho Signaling Pathway and Phosphorylation of VE-Cadherin

    PubMed Central

    Cai, Junting; Suber, Tomeka

    2017-01-01

    Maintenance of pulmonary endothelial barrier integrity is important for reducing severity of lung injury. Lysophosphatidic acid (LPA) regulates cell motility, cytoskeletal rearrangement, and cell growth. Knockdown of LPA receptor 1 (LPA1) has been shown to mitigate lung injury and pulmonary fibrosis. AM966, an LPA1 antagonist exhibiting an antifibrotic property, has been considered to be a future antifibrotic medicine. Here, we report an unexpected effect of AM966, which increases lung endothelial barrier permeability. An electric cell-substrate sensing (ECIS) system was used to measure permeability in human lung microvascular endothelial cells (HLMVECs). AM966 decreased the transendothelial electrical resistance (TEER) value immediately in a dose-dependent manner. VE-cadherin and f-actin double immunostaining reveals that AM966 increases stress fibers and gap formation between endothelial cells. AM966 induced phosphorylation of myosin light chain (MLC) through activation of RhoA/Rho kinase pathway. Unlike LPA treatment, AM966 had no effect on phosphorylation of extracellular signal-regulated kinases (Erk). Further, in LPA1 silencing cells, we observed that AM966-increased lung endothelial permeability as well as phosphorylation of VE-cadherin and focal adhesion kinase (FAK) were attenuated. This study reveals that AM966 induces lung endothelial barrier dysfunction, which is regulated by LPA1-mediated activation of RhoA/MLC and phosphorylation of VE-cadherin. PMID:28348461

  10. Involvement of lysophosphatidic acid in bone cancer pain by potentiation of TRPV1 via PKCε pathway in dorsal root ganglion neurons.

    PubMed

    Pan, Hai-Li; Zhang, Yu-Qiu; Zhao, Zhi-Qi

    2010-12-01

    It has been demonstrated that lysophosphatidic acid (LPA) released from injury tissue and transient receptor potential vanilloid 1 (TRPV1) receptor are implicated in the induction of chronic pain. In the present study we examined whether an interaction between LPA receptor LPA(1) and TRPV1 in dorsal root ganglion (DRG) neurons contributes to the development of bone cancer pain. Bone cancer was established by injection of mammary gland carcinoma cells into the rat tibia. Following the development of bone cancer pain, the TRPV1 expression and capsaicin-evoked currents were up-regulated in rat DRG neurons at L(4-6) segments. Immunohistochemistry staining revealed a high co-localization of LPA(1) with TRPV1 in DRG neurons. In isolated DRG neurons, whole-cell patch recording showed that capsaicin-induced currents were potentiated by LPA in a dose-dependent manner. The potentiation was blocked by either LPA(1) antagonist, protein kinase C (PKC) inhibitor or PKCε inhibitor, but not by protein kinase A (PKA) inhibitor or Rho inhibitor. In the behavioral tests, both mechanical allodynia and thermal hyperalgesia in bone cancer rats were attenuated by LPA(1) antagonist. LPA potentiates TRPV1 current via a PKCε-dependent pathway in DRG neurons of rats with bone cancer, which may be a novel peripheral mechanism underlying the induction of bone cancer pain.

  11. Overexpression of autotaxin, a lysophosphatidic acid-producing enzyme, enhances cardia bifida induced by hypo-sphingosine-1-phosphate signaling in zebrafish embryo.

    PubMed

    Nakanaga, Keita; Hama, Kotaro; Kano, Kuniyuki; Sato, Takanao; Yukiura, Hiroshi; Inoue, Asuka; Saigusa, Daisuke; Tokuyama, Hidetoshi; Tomioka, Yoshihisa; Nishina, Hiroshi; Kawahara, Atsuo; Aoki, Junken

    2014-04-01

    Lysophosphatidic acid (LPA) and sphingosine-1-phosphate (S1P) are second-generation lysophospholipid mediators that exert multiple biological functions through their own cognate receptors. They are both present in the blood stream, activate receptors with similar structures (endothelial differentiation gene receptors), have similar roles in the vasculature and are vasoactive. However, it is unclear whether these lysophospholipid mediators cross-talk downstream of each receptor. Here, we provide in vivo evidence that LPA signaling counteracted S1P signaling. When autotaxin (Atx), an LPA-producing enzyme, was overexpressed in zebrafish embryos by injecting atx mRNA, the embryos showed cardia bifida, a phenotype induced by down-regulation of S1P signaling. A similar cardiac phenotype was not induced when catalytically inactive Atx was introduced. The cardiac phenotype was synergistically enhanced when antisense morpholino oligonucleotides (MO) against S1P receptor (s1pr2/mil) or S1P transporter (spns2) was introduced together with atx mRNA. The Atx-induced cardia bifida was prominently suppressed when embryos were treated with an lpar1 receptor antagonist, Ki16425, or with MO against lpar1. These results provide the first in vivo evidence of cross-talk between LPA and S1P signaling.

  12. AM966, an Antagonist of Lysophosphatidic Acid Receptor 1, Increases Lung Microvascular Endothelial Permeability through Activation of Rho Signaling Pathway and Phosphorylation of VE-Cadherin.

    PubMed

    Cai, Junting; Wei, Jianxin; Li, Shuang; Suber, Tomeka; Zhao, Jing

    2017-01-01

    Maintenance of pulmonary endothelial barrier integrity is important for reducing severity of lung injury. Lysophosphatidic acid (LPA) regulates cell motility, cytoskeletal rearrangement, and cell growth. Knockdown of LPA receptor 1 (LPA1) has been shown to mitigate lung injury and pulmonary fibrosis. AM966, an LPA1 antagonist exhibiting an antifibrotic property, has been considered to be a future antifibrotic medicine. Here, we report an unexpected effect of AM966, which increases lung endothelial barrier permeability. An electric cell-substrate sensing (ECIS) system was used to measure permeability in human lung microvascular endothelial cells (HLMVECs). AM966 decreased the transendothelial electrical resistance (TEER) value immediately in a dose-dependent manner. VE-cadherin and f-actin double immunostaining reveals that AM966 increases stress fibers and gap formation between endothelial cells. AM966 induced phosphorylation of myosin light chain (MLC) through activation of RhoA/Rho kinase pathway. Unlike LPA treatment, AM966 had no effect on phosphorylation of extracellular signal-regulated kinases (Erk). Further, in LPA1 silencing cells, we observed that AM966-increased lung endothelial permeability as well as phosphorylation of VE-cadherin and focal adhesion kinase (FAK) were attenuated. This study reveals that AM966 induces lung endothelial barrier dysfunction, which is regulated by LPA1-mediated activation of RhoA/MLC and phosphorylation of VE-cadherin.

  13. Quantitative Phosphoproteome Analysis of Lysophosphatidic Acid Induced Chemotaxis applying Dual-step ¹⁸O Labeling Coupled with Immobilized Metal-ion Affinity Chromatography

    SciTech Connect

    Ding, Shi-Jian; Wang, Yingchun; Jacobs, Jon M.; Qian, Weijun; Yang, Feng; Tolmachev, Aleksey V.; Du, Xiuxia; Wang, Wei; Moore, Ronald J.; Monroe, Matthew E.; Purvine, Samuel O.; Waters, Katrina M.; Heibeck, Tyler H.; Adkins, Joshua N.; Camp, David G.; Klemke, Richard L.; Smith, Richard D.

    2008-10-01

    Reversible protein phosphorylation is a central cellular regulatory mechanism in modulating protein activity and propagating signals within cellular pathways and networks. Development of more effective methods for the simultaneous identification of phosphorylation sites and quantification of temporal changes in protein phosphorylation could provide important insights into molecular signaling mechanisms in a variety of different cellular processes. Here we present an integrated quantitative phosphoproteomics approach and its applications for comparative analysis of Cos-7 cells in response to lysophosphatidic acid (LPA) gradient stimulation. The approach combines trypsin-catalyzed 16O/18O labeling plus 16O/18O-methanol esterification labeling for quantitation, a macro- Immobilized Metal-ion Affinity Chromatography trap for phosphopeptide enrichment, and a monolithic capillary column with integrated electrospray emitter. LC separation and MS/MS is followed by neutral loss-dependent MS/MS/MS for phosphopeptide identification using a linear ion trap (LTQ)-FT mass spectrometer and complementary searching algorithms for interpreting MS/MS spectra. Protein phosphorylation involved in various signaling pathways of cell migration were identified and quantified, such as mitogen-activated protein kinase 1, dual-specificity mitogen-activated protein kinase kinase 2, and dual-specificity tyrosine-phosphorylation regulated kinase 1b, and a number of Rho GTPase-activating proteins. These results demonstrate the efficiency of this quantitative phosphoproteomics approach and its application for rapid discovery of phosphorylation events associated with gradient sensing and cell chemotaxis.

  14. Suppression of lysophosphatidic acid and lysophosphatidylcholine formation in the plasma in vitro: proposal of a plasma sample preparation method for laboratory testing of these lipids.

    PubMed

    Nakamura, Kazuhiro; Kishimoto, Tatsuya; Ohkawa, Ryunosuke; Okubo, Shigeo; Tozuka, Minoru; Yokota, Hiromitsu; Ikeda, Hitoshi; Ohshima, Noriko; Mizuno, Koji; Yatomi, Yutaka

    2007-08-01

    It is now established that lysophosphatidic acid (LPA) and lysophosphatidylcholine (LPC) play important roles in a variety of biological responses, especially in the area of vascular biology, and determination of their concentrations in the plasma is believed to be clinically relevant. Preparation of the measurement samples is a difficult task, however, because the blood levels of these lipids can be easily increased by in vitro manipulation after venepuncture. In this study, we examined the optimal conditions for the preparation of plasma samples for the measurement of LPA and LPC. It appears that regulation of platelet activation and the enzymatic activity of lysophospholipase D/autotaxin and lecithin-cholesterol acyltransferase is important to suppress the undesirable formation of LPA and LPC after venepuncture. We found that in vitro formation of LPA and LPC was negligible when whole blood samples were mixed with 7.5 mM EDTA plus 10% (v/v) citrate-theophylline-adenosine-dipyridamole (CTAD) and when all of the procedures, including the plasma preparation and preservation until measurement, were performed at 4 degrees C. Thus, although the plasma levels of LPA and LPC can be easily altered, laboratory testing of these important bioactive lipids for clinical purposes may be conducted reliably if the samples are prepared under stringent conditions.

  15. Transgenic 6F tomatoes act on the small intestine to prevent systemic inflammation and dyslipidemia caused by Western diet and intestinally derived lysophosphatidic acid.

    PubMed

    Navab, Mohamad; Hough, Greg; Buga, Georgette M; Su, Feng; Wagner, Alan C; Meriwether, David; Chattopadhyay, Arnab; Gao, Feng; Grijalva, Victor; Danciger, Janet S; Van Lenten, Brian J; Org, Elin; Lusis, Aldons J; Pan, Calvin; Anantharamaiah, G M; Farias-Eisner, Robin; Smyth, Susan S; Reddy, Srinivasa T; Fogelman, Alan M

    2013-12-01

    We recently reported that levels of unsaturated lysophosphatidic acid (LPA) in the small intestine significantly correlated with the extent of aortic atherosclerosis in LDL receptor-null (LDLR⁻/⁻) mice fed a Western diet (WD). Here we demonstrate that WD increases unsaturated (but not saturated) LPA levels in the small intestine of LDLR⁻/⁻ mice and causes changes in small intestine gene expression. Confirmation of microarray analysis by quantitative RT-PCR showed that adding transgenic tomatoes expressing the apoA-I mimetic peptide 6F (Tg6F) to WD prevented many WD-mediated small intestine changes in gene expression. If instead of feeding WD, unsaturated LPA was added to chow and fed to the mice: i) levels of LPA in the small intestine were similar to those induced by feeding WD; ii) gene expression changes in the small intestine mimicked WD-mediated changes; and iii) changes in plasma serum amyloid A, total cholesterol, triglycerides, HDL-cholesterol levels, and the fast-performance liquid chromatography lipoprotein profile mimicked WD-mediated changes. Adding Tg6F (but not control tomatoes) to LPA-supplemented chow prevented the LPA-induced changes. We conclude that: i) WD-mediated systemic inflammation and dyslipidemia may be in part due to WD-induced increases in small intestine LPA levels; and ii) Tg6F reduces WD-mediated systemic inflammation and dyslipidemia by preventing WD-induced increases in LPA levels in the small intestine.

  16. Potentials of the circulating pruritogenic mediator lysophosphatidic acid in development of allergic skin inflammation in mice: role of blood cell-associated lysophospholipase D activity of autotaxin.

    PubMed

    Shimizu, Yoshibumi; Morikawa, Yoshiyuki; Okudaira, Shinichi; Kimoto, Shigenobu; Tanaka, Tamotsu; Aoki, Junken; Tokumura, Akira

    2014-05-01

    Itching and infiltration of immune cells are important hallmarks of atopic dermatitis (AD). Although various studies have focused on peripheral mediator-mediated mechanisms, systemic mediator-mediated mechanisms are also important in the pathogenesis and development of AD. Herein, we found that intradermal injection of lysophosphatidic acid (LPA), a bioactive phospholipid, induces scratching responses by Institute of Cancer Research mice through LPA1 receptor- and opioid μ receptor-mediating mechanisms, indicating its potential as a pruritogen. The circulating level of LPA in Naruto Research Institute Otsuka Atrichia mice, a systemic AD model, with severe scratching was found to be higher than that of control BALB/c mice, probably because of the increased lysophospholipase D activity of autotaxin (ATX) in the blood (mainly membrane associated) rather than in plasma (soluble). Heparan sulfate proteoglycan was shown to be involved in the association of ATX with blood cells. The sequestration of ATX protein on the blood cells by heparan sulfate proteoglycan may accelerate the transport of LPA to the local apical surface of vascular endothelium with LPA receptors, promoting the hyperpermeability of venules and the pathological uptake of immune cells, aggravating lesion progression and itching in Naruto Research Institute Otsuka Atrichia mice.

  17. Lysophosphatidic acid prevents apoptosis of Caco-2 colon cancer cells via activation of mitogen-activated protein kinase and phosphorylation of Bad.

    PubMed

    Rusovici, Raluca; Ghaleb, Amr; Shim, Hyunsuk; Yang, Vincent W; Yun, C Chris

    2007-08-01

    Lysophosphatidic acids (LPA) exert growth factor-like effects through specific G protein-coupled receptors. The presence of different LPA receptors often determines the specific signaling mechanisms and the physiological consequences of LPA in different environments. Among the four members of the LPA receptor family, LPA(2) has been shown to be overexpressed in colon cancer suggesting that the signaling by LPA(2) may potentiate growth and survival of tumor cells. In this study, we examined the effect of LPA on survival of colon cancer cells using Caco-2 cells as a cell model system. LPA rescued Caco-2 cells from apoptosis elicited by the chemotherapeutic drug, etoposide. This protection was accompanied by abrogation of etoposide-induced stimulation of caspase activity via a mechanism dependent on Erk and PI3K. In contrast, perturbation of cellular signaling mediated by the LPA(2) receptor by knockdown of a scaffold protein NHERF2 abrogated the protective effect of LPA. Etoposide decreased the expression of Bcl-2, which was reversed by LPA. Etoposide decreased the phosphorylation level of the proapoptotic protein Bad in an Erk-dependent manner, without changing Bad expression. We further show that LPA treatment resulted in delayed activation of Erk. These results indicate that LPA protects Caco-2 cells from apoptotic insult by a mechanism involving Erk, Bad, and Bcl-2.

  18. Lysophosphatidic acid mediates the rapid activation of platelets and endothelial cells by mildly oxidized low density lipoprotein and accumulates in human atherosclerotic lesions.

    PubMed

    Siess, W; Zangl, K J; Essler, M; Bauer, M; Brandl, R; Corrinth, C; Bittman, R; Tigyi, G; Aepfelbacher, M

    1999-06-08

    Oxidized low density lipoprotein (LDL) is a key factor in the pathogenesis of atherosclerosis and its thrombotic complications, such as stroke and myocardial infarction. It activates endothelial cells and platelets through mechanisms that are largely unknown. Here, we show that lysophosphatidic acid (LPA) was formed during mild oxidation of LDL and was the active compound in mildly oxidized LDL and minimally modified LDL, initiating platelet activation and stimulating endothelial cell stress-fiber and gap formation. Antagonists of the LPA receptor prevented platelet and endothelial cell activation by mildly oxidized LDL. We also found that LPA accumulated in and was the primary platelet-activating lipid of atherosclerotic plaques. Notably, the amount of LPA within the human carotid atherosclerotic lesion was highest in the lipid-rich core, the region most thrombogenic and most prone to rupture. Given the potent biological activity of LPA on platelets and on cells of the vessel wall, our study identifies LPA as an atherothrombogenic molecule and suggests a possible strategy to prevent and treat atherosclerosis and cardiocerebrovascular diseases.

  19. A novel approach for measuring sphingosine-1-phosphate and lysophosphatidic acid binding to carrier proteins using monoclonal antibodies and the Kinetic Exclusion Assay.

    PubMed

    Fleming, Jonathan K; Glass, Thomas R; Lackie, Steve J; Wojciak, Jonathan M

    2016-09-01

    Sphingosine-1-phosphate (S1P) and lysophosphatidic acid (LPA) are bioactive signaling lysophospholipids that activate specific G protein-coupled receptors on the cell surface triggering numerous biological events. In circulation, S1P and LPA associate with specific carrier proteins or chaperones; serum albumin binds both S1P and LPA while HDL shuttles S1P via interactions with apoM. We used a series of kinetic exclusion assays in which monoclonal anti-S1P and anti-LPA antibodies competed with carrier protein for the lysophospholipid to measure the equilibrium dissociation constants (Kd) for these carrier proteins binding S1P and the major LPA species. Fatty acid-free (FAF)-BSA binds these lysophospholipids with the following Kd values: LPA(16:0), 68 nM; LPA(18:1), 130 nM; LPA(18:2), 350 nM; LPA(20:4), 2.2 μM; and S1P, 41 μM. FAF human serum albumin binds each lysophospholipid with comparable affinities. By measuring the apoM concentration and expanding the model to include endogenous ligand, we were able to resolve the Kd values for S1P binding apoM in the context of human HDL and LDL particles (21 nM and 2.4 nM, respectively). The novel competitive assay and analysis described herein enables measurement of Kd values of completely unmodified lysophospholipids binding unmodified carrier proteins in solution, and thus provide insights into S1P and LPA storage in the circulation system and may be useful in understanding chaperone-dependent receptor activation and signaling. Copyright © 2016 by the American Society for Biochemistry and Molecular Biology, Inc.

  20. Activation of lysophosphatidic acid receptor by gintonin inhibits Kv1.2 channel activity: involvement of tyrosine kinase and receptor protein tyrosine phosphatase α.

    PubMed

    Lee, Jun-Ho; Choi, Sun-Hye; Lee, Byung-Hwan; Hwang, Sung-Hee; Kim, Hyeon-Joong; Rhee, Jeehae; Chung, Chihye; Nah, Seung-Yeol

    2013-08-26

    Gintonin is a novel ginseng-derived G protein-coupled lysophosphatidic acid (LPA) receptor ligand. The primary action of gintonin is to elicit a transient increase in [Ca(2+)]i via activation of LPA receptor subtypes. Voltage-gated potassium (Kv) channels play important roles in synaptic transmission in nervous systems. The previous reports have shown that Kv channels can be regulated by Gαq/11 protein-coupled receptor ligands. In the present study, we examined the effects of gintonin on Kv1.2 channel activity expressed in Xenopus oocytes after injection of RNA encoding the human Kv1.2 α subunit. Gintonin treatment inhibited Kv1.2 channel activity in reversible and concentration-dependent manners. The inhibitory effect of gintonin on Kv1.2 channel activity was blocked by active phospholipase C inhibitor, inositol 1,4,5-triphosphate receptor antagonist, and intracellular Ca(2+) chelator. The co-expression of active receptor protein tyrosine phosphatase α (RPTPα) with Kv1.2 channel greatly attenuated gintonin-mediated inhibition of Kv1.2 channel activity, but attenuation was not observed with catalytically inactive RPTPα. Furthermore, neither genistein, a tyrosine kinase inhibitor, nor site-directed mutation of a tyrosine residue (Y132 to Y132F), which is phosphorylated by tyrosine kinase of the N-terminal of the Kv1.2 channel α subunit, significantly attenuated gintonin-mediated inhibition of Kv1.2 channel activity. These results indicate that the gintonin-mediated Kv1.2 channel regulation involves the dual coordination of both tyrosine kinase and RPTPα coupled to this receptor. Finally, gintonin-mediated regulation of Kv1.2 channel activity might explain one of the modulations of gintonin-mediated neuronal activities in nervous systems.

  1. Expression of ecto-lipid phosphate phosphohydrolases in 3T3F442A preadipocytes and adipocytes. Involvement in the control of lysophosphatidic acid production

    PubMed Central

    Simon, Marie Francoise; Rey, Astrid; Castan-Laurel, Isabelle; Grés, Sandra; Sibrac, David; Valet, Philippe; Saulnier-Blache, Jean Sébastien

    2002-01-01

    SUMMARY Because of its production by adipocytes and its ability to increase preadipocyte proliferation, lysophosphatidic acid (LPA) could participate to the paracrine control of adipose tissue development. The aim of the present study was to determine which enzyme activities are involved in exogenous LPA hydrolysis by preadipocytes and adipocytes. Using a quantitative method, we observed that extracellular LPA rapidly disappeared from the culture medium of 3T3F442A preadipocytes. This disappearance was strongly slowed down in the presence of the phosphatase inhibitors, sodium vanadate and sodium pervanadate. By using [33P]LPA on intact 3T3F442A preadipocytes, we found that 90% of LPA hydrolysis resulted from LPA phosphatase activity biochemicaly related to previously described ecto-lipid phosphate phosphohydrolases (LPP). Quantitative real time RT-PCR revealed that 3T3F442A preadipocytes expressed mRNAs of three known LPP subtypes (-1, -2 and -3), with a predominant expression of LPP-1 and LPP-3. Differentiation of 3T3F442A preadipocytes into adipocytes led to 80% reduction in ecto-LPA-phosphatase activity, with a concomitant down-regulation in LPP-1, LPP-2, and LPP-3 mRNA expression. In spite of this regulation, treatment of 3T3F442A adipocytes with sodium vanadate increased LPA production in the culture medium, suggesting the involvement of ecto-LPA phosphatase activity in the control of extracellular production of LPA by adipocytes. In conclusion, these data demonstrate that hydrolysis of extracellular LPA by preadipocytes and adipocytes mainly results from a dephosphorylation activity. This activity: (i) occurs at the extracellular face of cell membrane; (ii) exhibits similar biochemical characteristics than to the LPP; (iii) is negatively regulated during adipocyte differentiation, (ii) and plays an important role in the control of extracellular LPA production by adipocytes. Ecto-LPA-phosphatase activity represents a potential target to control adipose tissue

  2. Autotaxin is released from adipocytes, catalyzes lysophosphatidic acid synthesis, and activates preadipocyte proliferation. Up-regulated expression with adipocyte differentiation and obesity

    PubMed Central

    Ferry, Gilles; Tellier, Edwige; Try, Anne; Grés, Sandra; Naime, Isabelle; Simon, Marie Françoise; Rodriguez, Marianne; Boucher, Jérémie; Tack, Ivan; Gesta, Stéphane; Chomarat, Pascale; Dieu, Marc; Raes, Martine; Galizzi, Jean Pierre; Valet, Philippe; Boutin, Jean A.; Saulnier-Blache, Jean Sébastien

    2003-01-01

    Our group has recently demonstrated (Gesta et al. J. Lipid. Res, 2002, 43:904–910) the presence, in adipocyte conditioned-medium, of a soluble lysophospholipase D-activity (LPLDact) involved in synthesis of the bioactive phospholipid, lysophosphatidic acid (LPA). In the present report, LPLDact was purified from 3T3F442A-adipocyte conditioned-medium and identified as the type II ecto-nucleotide pyrophosphatase phosphodiesterase: autotaxin (ATX). A unique ATX cDNA was cloned from 3T3F442A-adipocytes, and its recombinant expression in COS-7 cells led to extracellular release of LPLDact. ATX mRNA expression was highly up-regulated during adipocyte differentiation of 3T3F442A-preadipocytes. This up-regulation was paralleled by the ability of newly differentiated adipocytes to release LPLDact and LPA. Differentiation-dependent up-regulation of ATX expression was also observed in primary culture of mouse preadipocytes. Treatment of 3T3F442A-preadipocytes with concentrated conditioned medium from ATX expressing-COS-7 cells led to an increase in cell number as compared with concentrated conditioned medium from ATX non-expressing-COS-7 cells. The specific effect of ATX on preadipocyte proliferation was completely suppressed by co-treatment with a LPA-hydrolyzing phospholipase, phospholipase B. Finally, ATX expression was found in mature adipocytes isolated from mouse adipose tissue, and was substantially increased in genetically obese-diabetic db/db mice when compared to their lean siblings. In conclusion, the present work shows that ATX is responsible for the LPLDact released by adipocytes, and exerts a paracrine control on preadipocyte growth via an LPA-dependent mechanism. Up-regulations of ATX expression with adipocyte differentiation and genetic obesity suggest a possible involvement of this released protein in the development of adipose tissue and obesity-associated pathologies. PMID:12642576

  3. Adult Lysophosphatidic Acid Receptor 1-Deficient Rats with Hyperoxia-Induced Neonatal Chronic Lung Disease Are Protected against Lipopolysaccharide-Induced Acute Lung Injury

    PubMed Central

    Chen, Xueyu; Walther, Frans J.; Laghmani, El H.; Hoogeboom, Annemarie M.; Hogen-Esch, Anne C. B.; van Ark, Ingrid; Folkerts, Gert; Wagenaar, Gerry T. M.

    2017-01-01

    Aim: Survivors of neonatal chronic lung disease or bronchopulmonary dysplasia (BPD) suffer from compromised lung function and are at high risk for developing lung injury by multiple insults later in life. Because neonatal lysophosphatidic acid receptor-1 (LPAR1)-deficient rats are protected against hyperoxia-induced lung injury, we hypothesize that LPAR1-deficiency may protect adult survivors of BPD from a second hit response against lipopolysaccharides (LPS)-induced lung injury. Methods: Directly after birth, Wistar control and LPAR1-deficient rat pups were exposed to hyperoxia (90%) for 8 days followed by recovery in room air. After 7 weeks, male rats received either LPS (2 mg kg−1) or 0.9% NaCl by intraperitoneal injection. Alveolar development and lung inflammation were investigated by morphometric analysis, IL-6 production, and mRNA expression of cytokines, chemokines, coagulation factors, and an indicator of oxidative stress. Results: LPAR1-deficient and control rats developed hyperoxia-induced neonatal emphysema, which persisted into adulthood, as demonstrated by alveolar enlargement and decreased vessel density. LPAR1-deficiency protected against LPS-induced lung injury. Adult controls with BPD exhibited an exacerbated response toward LPS with an increased expression of pro-inflammatory mRNAs, whereas LPAR1-deficient rats with BPD were less sensitive to this “second hit” with a decreased pulmonary influx of macrophages and neutrophils, interleukin-6 (IL-6) production, and mRNA expression of IL-6, monocyte chemoattractant protein-1, cytokine-induced neutrophil chemoattractant 1, plasminogen activator inhibitor-1, and tissue factor. Conclusion: LPAR1-deficient rats have increased hyperoxia-induced BPD survival rates and, despite the presence of neonatal emphysema, are less sensitive to an aggravated “second hit” than Wistar controls with BPD. Intervening in LPA-LPAR1-dependent signaling may not only have therapeutic potential for neonatal chronic

  4. Aromatic hydrocarbon receptor inhibits lysophosphatidic acid-induced vascular endothelial growth factor-A expression in PC-3 prostate cancer cells

    SciTech Connect

    Wu, Pei-Yi; Lin, Yueh-Chien; Lan, Shun-Yan; Huang, Yuan-Li; Lee, Hsinyu

    2013-08-02

    Highlights: •LPA-induced VEGF-A expression was regulated by HIF-1α and ARNT. •PI3K mediated LPA-induced VEGF-A expression. •AHR signaling inhibited LPA-induced VEGF-A expression in PC-3 cells. -- Abstract: Lysophosphatidic acid (LPA) is a lipid growth factor with multiple biological functions and has been shown to stimulate cancer cell secretion of vascular endothelial growth factor-A (VEGF-A) and trigger angiogenesis. Hypoxia-inducible factor-1 (HIF-1), a heterodimer consisting of HIF-1α and HIF-1β (also known as aromatic hydrocarbon receptor nuclear translocator (ARNT)) subunits, is an important regulator of angiogenesis in prostate cancer (PC) through the enhancement of VEGF-A expression. In this study, we first confirmed the ability of LPA to induce VEGF-A expression in PC-3 cells and then validated that LPA-induced VEGF-A expression was regulated by HIF-1α and ARNT through phosphatidylinositol 3-kinase activation. Aromatic hydrocarbon receptor (AHR), a receptor for dioxin-like compounds, functions as a transcription factor through dimerization with ARNT and was found to inhibit prostate carcinogenesis and vanadate-induced VEGF-A production. Since ARNT is a common dimerization partner of AHR and HIF-1α, we hypothesized that AHR might suppress LPA-induced VEGF-A expression in PC-3 cells by competing with HIF-1α for ARNT. Here we demonstrated that overexpression and ligand activation of AHR inhibited HIF-1-mediated VEGF-A induction by LPA treatment of PC-3 cells. In conclusion, our results suggested that AHR activation may inhibit LPA-induced VEGF-A expression in PC-3 cells by attenuating HIF-1α signaling, and subsequently, suppressing angiogenesis and metastasis of PC. These results suggested that AHR presents a potential therapeutic target for the prevention of PC metastasis.

  5. An Lysophosphatidic Acid Receptors 1 and 3 Axis Governs Cellular Senescence of Mesenchymal Stromal Cells and Promotes Growth and Vascularization of Multiple Myeloma.

    PubMed

    Kanehira, Masahiko; Fujiwara, Tohru; Nakajima, Shinji; Okitsu, Yoko; Onishi, Yasushi; Fukuhara, Noriko; Ichinohasama, Ryo; Okada, Yoshinori; Harigae, Hideo

    2017-03-01

    Mesenchymal stromal cells (MSCs) are multipotent progenitor cells and there is much interest in how MSCs contribute to the regulation of the tumor microenvironment. Whether MSCs exert a supportive or suppressive effect on tumor progression is still controversial, but is likely dependent on a variety of factors that are tumor-type dependent. Multiple myeloma (MM) is characterized by growth of malignant plasma cells in the bone marrow. It has been shown that the progression of MM is governed by MSCs, which act as a stroma of the myeloma cells. Although stroma is created via mutual communication between myeloma cells and MSCs, the mechanism is poorly understood. Here we explored the role of lysophosphatidic acid (LPA) signaling in cellular events where MSCs were converted into either MM-supportive or MM-suppressive stroma. We found that myeloma cells stimulate MSCs to produce autotaxin, an indispensable enzyme for the biosynthesis of LPA, and LPA receptor 1 (LPA1) and 3 (LPA3) transduce opposite signals to MSCs to determine the fate of MSCs. LPA3-silenced MSCs (siLPA3-MSCs) exhibited cellular senescence-related phenotypes in vitro, and significantly promoted progression of MM and tumor-related angiogenesis in vivo. In contrast, siLPA1-MSCs showed resistance to cellular senescence in vitro, and efficiently delayed progression of MM and tumor-related angiogenesis in vivo. Consistently, anti-MM effects obtained by LPA1-silencing in MSCs were completely reproduced by systemic administration of Ki6425, an LPA1 antagonist. Collectively, our results indicate that LPA signaling determines the fate of MSCs and has potential as a therapeutic target in MM. Stem Cells 2017;35:739-753.

  6. Lysophosphatidic acid-induced vascular neointimal formation in mouse carotid arteries is mediated by the matricellular protein CCN1/Cyr61.

    PubMed

    Hao, Feng; Zhang, Fuqiang; Wu, Daniel Dongwei; An, Dong; Shi, Jing; Li, Guohong; Xu, Xuemin; Cui, Mei-Zhen

    2016-12-01

    Vascular smooth muscle cell (SMC) migration is an essential step involved in neointimal formation in restenosis and atherosclerosis. Lysophosphatidic acid (LPA) is a bioactive component of oxidized low-density lipoprotein and is produced by activated platelets, implying that LPA influences vascular remodeling. Our previous study revealed that matricellular protein CCN1, a prominent extracellular matrix (ECM) protein, mediates LPA-induced SMC migration in vitro. Here we examined the role of CCN1 in LPA-induced neointimal formation. By using LPA infusion of carotid artery in a mouse model, we demonstrated that LPA highly induced CCN1 expression (approximately six- to sevenfold) in neointimal lesions. Downregulation of CCN1 expression with the specific CCN1 siRNA in carotid arteries blocked LPA-induced neointimal formation, indicating that CCN1 is essential in LPA-induced neointimal formation. We then used LPA receptor knockout (LPA1-/-, LPA2-/-, and LPA3-/-) mice to examine LPA receptor function in CCN1 expression in vivo and in LPA-induced neointimal formation. Our data reveal that LPA1 deficiency, but not LPA2 or LPA3 deficiency, prevents LPA-induced CCN1 expression in vivo in mouse carotid arteries. We also observed that LPA1 deficiency blunted LPA infusion-induced neointimal formation, indicating that LPA1 is the major mediator for LPA-induced vascular remodeling. Our in vivo model of LPA-induced neointimal formation established a key role of the ECM protein CCN1 in mediating LPA-induced neointimal formation. Our data support the notion that the LPA1-CCN1 axis may be the central control for SMC migration and vascular remodeling. CCN1 may serve as an important vascular disease marker and potential target for vascular therapeutic intervention. Copyright © 2016 the American Physiological Society.

  7. Identification of Lysophosphatidic Acid Receptor 1 in Astroglial Cells as a Target for Glial Cell Line-derived Neurotrophic Factor Expression Induced by Antidepressants.

    PubMed

    Kajitani, Naoto; Miyano, Kanako; Okada-Tsuchioka, Mami; Abe, Hiromi; Itagaki, Kei; Hisaoka-Nakashima, Kazue; Morioka, Norimitsu; Uezono, Yasuhito; Takebayashi, Minoru

    2016-12-30

    Preclinical and clinical evidence suggests that glial cell line-derived neurotrophic factor (GDNF) is important in the therapeutic effect of antidepressants. A previous study demonstrated that the tricyclic antidepressant amitriptyline induces Gαi/o activation, which leads to GDNF expression in astrocytes. However, the specific target expressed in astrocytes that mediates antidepressant-evoked Gαi/o activation has yet to be identified. Thus, the current study explored the possibility that antidepressant-induced Gαi/o activation depends on lysophosphatidic acid receptor 1 (LPAR1), a Gαi/o-coupled receptor. GDNF mRNA expression was examined using real-time PCR and Gαi/o activation was examined using the cell-based receptor assay system CellKey(TM) in rat C6 astroglial cells and rat primary cultured astrocytes. LPAR1 antagonists blocked GDNF mRNA expression and Gαi/o activation evoked by various classes of antidepressants (amitriptyline, nortriptyline, mianserin, and fluoxetine). In addition, deletion of LPAR1 by RNAi suppressed amitriptyline-evoked GDNF mRNA expression. Treatment of astroglial cells with the endogenous LPAR agonist LPA increased GDNF mRNA expression through LPAR1, whereas treatment of primary cultured neurons with LPA failed to affect GDNF mRNA expression. Astrocytic GDNF expression evoked by either amitriptyline or LPA utilized, in part, transactivation of fibroblast growth factor receptor and a subsequent ERK cascade. The current results suggest that LPAR1 is a novel, specific target of antidepressants that leads to GDNF expression in astrocytes. © 2016 by The American Society for Biochemistry and Molecular Biology, Inc.

  8. A transgenic mouse model for the in vivo bioluminescence imaging of the expression of the lysophosphatidic acid receptor 3: relevance for inflammation and uterine physiology research.

    PubMed

    Zhao, Chenqi; Sardella, Anne; Davis, Lynn; Poubelle, Patrice E; Bourgoin, Sylvain G; Fernandes, Maria J

    2015-08-01

    Lysophosphatidic acid (LPA) is a lipid-derived signaling molecule that plays key roles in diverse biological processes including inflammation and uterine remodeling. Although the function of LPA and its receptors has been extensively studied using knock-out mice, the temporal-spatial expression of LPA receptors is less well-characterized. To gain further insight into the dynamic regulation of LPA receptor 3 (Lpar3) expression in vivo by bioluminescence imaging, we generated and characterized mice transgenic for a putative Lpar3 promoter fragment. A non-coding region of the Lpar3 gene immediately upstream of the start site was subcloned adjacent to the luciferase gene. Promoter activity was determined by in vitro luciferase assays, in vivo bioluminescent imaging or by semi-quantitative real-time PCR. The air-pouch model was used to investigate Lpar3 promoter activity in the context of inflammation. The putative Lpar3 promoter fragment behaved similarly to the endogenous promoter in vitro and in vivo. In male mice, elevated levels of Lpar3-induced luciferase activity were observed in the testis. In female mice, the basal level of luciferase activity in the uterus significantly increased during pseudopregnancy. Moreover, luciferase activity was upregulated by TNF-α in the air-pouch model. We report the identification of a functional Lpar3 promoter fragment and the generation of a transgenic mouse model to investigate the regulation of Lpar3 promoter activity non-invasively in vivo by bioluminescence imaging. This mouse model is a valuable tool for reproductive biology and inflammation research as well as other biological processes in which this receptor is involved.

  9. Botulinum toxin type A targets RhoB to inhibit lysophosphatidic acid-stimulated actin reorganization and acetylcholine release in nerve growth factor-treated PC12 cells.

    PubMed

    Ishida, Hiroshi; Zhang, Xieping; Erickson, Kelly; Ray, Prabhati

    2004-09-01

    Botulinum toxin type A (BoNT/A) produced by Clostridium botulinum inhibits Ca2+-dependent acetylcholine (ACh) release (neuroexocytosis) at peripheral neuromuscular junctions, sometimes causing neuromuscular paralysis. This inhibitory effect is attributed to its metalloprotease activity to cleave the 25-kDa synaptosomal-associated protein, which is essential for the exocytotic machinery. However, deletion of this protein does not result in a complete block of neuroexocytosis, suggesting that botulinum-mediated inhibition may occur via another mechanism. Rho GTPases, a class of small GTP-binding proteins (G proteins), control actin cytoskeletal organization, thereby regulating a variety of cellular functions in various cells, including neuronal cells. We have shown that the G protein activator lysophosphatidic acid (LPA) triggered actin reorganization followed by Ca2+-dependent ACh release in nerve growth factor-treated PC12 cells and that BoNT/A blocked both events through degradation of RhoB by the proteasome. Overexpression of wild-type RhoB caused actin reorganization and enhanced the release of ACh by LPA to overcome toxin's inhibitory effect on actin reorganization/exocytosis stimulated by LPA, whereas overexpression of a dominant negative RhoB inhibited ACh release, regardless of LPA and/or toxin treatment. Finally, a knockdown of the RhoB gene via sequence-specific, post-transcriptional gene silencing reduced RhoB expression in PC12 cells, resulting in total inhibition of both actin reorganization and ACh release induced by LPA. We conclude that the RhoB signaling pathway regulates ACh release via actin cytoskeletal reorganization and that botulinum toxin inhibits neuroexocytosis by targeting RhoB pathway.

  10. The significance of the altered expression of lysophosphatidic acid receptors, autotaxin and phospholipase A2 as the potential biomarkers in type 1 endometrial cancer biology.

    PubMed

    Wasniewski, Tomasz; Woclawek-Potocka, Izabela; Boruszewska, Dorota; Kowalczyk-Zieba, Ilona; Sinderewicz, Emilia; Grycmacher, Katarzyna

    2015-11-01

    In order to study lysophosphatidic acid (LPA) signaling associated with type 1 endometrial carcinoma (EC), we evaluated the LPA receptors (LPARs), autotaxin (ATX) and phospholipase A2 (PLA2) expression in EC and normal endometrium with correlation to clinicopathological features. We investigated LPAR1, LPAR2, LPAR3, LPAR4, ATX and PLA2 expression at mRNA and protein levels using quantitative real-time PCR and western blot analyses in 37 ECs and 10 normal endometria. All the examined LPARs (except for LPAR3 protein), ATX and PLA2 were overexpressed in cancerous compared to healthy endometrium. The studied ECs showed the highest LPAR2 and LPAR1 expression. Statistically positive correlations were found between depth of myoinvasion and levels of LPAR1, LPAR2 and PLA2 transcripts and proteins. We also found positive correlations between LPAR1, LPAR2, LPAR4 and PLA2 expression with the International Federation of Gynecology and Obstetrics (FIGO) stage. The expression of LPAR1, LPAR2 and PLA2 was positively associated with the age of patients. Positive correlations were found between the expression of LPAR1 mRNA, LPAR2 mRNA and protein and LPAR3 mRNA and body mass index (BMI) of the examined patients. We found no association between the expression levels of the studied factors and diabetes or hypertension among the examined patients. Owing to the highest LPAR2 and LPAR1 expression in EC and positive correlations of these two receptors with the depth of myoinvasion and the FIGO stage, we believe that LPAR2 and LPAR1 show promise as predictors of the EC progression as well as the main receptors responsible for LPA action in the EC tissue.

  11. Lysophosphatidic acid induces both EGFR-dependent and EGFR-independent effects on DNA synthesis and migration in pancreatic and colorectal carcinoma cells.

    PubMed

    Tveteraas, Ingun Heiene; Aasrum, Monica; Brusevold, Ingvild Johnsen; Ødegård, John; Christoffersen, Thoralf; Sandnes, Dagny

    2016-02-01

    Lysophosphatidic acid (LPA) is a small glycerophospholipid ubiquitously present in tissues and plasma. It acts through receptors belonging to the G-protein-coupled receptor (GPCR) family, is involved in several biological processes, and is strongly implicated in different cancers. In this paper, we have investigated the effects of LPA on DNA synthesis and migration in a panel of pancreatic and colon cancer cells, with particular focus on the involvement of the epidermal growth factor (EGF) receptor (EGFR) in LPA-induced signaling. LPA stimulated DNA synthesis and/or migration in all the cell lines included in this study. In five of the six cell lines, LPA induced phosphorylation of the EGFR, and the effects on EGFR and Akt, and in some of the cells also ERK, were sensitive to the EGFR tyrosine kinase inhibitor gefitinib, strongly suggesting LPA-induced EGFR transactivation in these cells. In contrast, in one of the pancreatic carcinoma cell lines (Panc-1), we found no evidence of transactivation of the EGFR. In the pancreatic carcinoma cell lines where transactivation took place (BxPC3, AsPC1, HPAFII), gefitinib reduced LPA-induced DNA synthesis and/or migration. However, we also found evidence of transactivation in the two colon carcinoma cell lines (HT29, HCT116) although gefitinib did not inhibit LPA-induced DNA synthesis or migration in these cells. Taken together, the data indicate that in many gastrointestinal carcinoma cells, LPA uses EGFR transactivation as a mechanism when exerting such effects as stimulation of cell proliferation and migration, but EGFR-independent pathways may be involved instead of, or in concerted action with, the EGFR transactivation.

  12. Increased Expression of CYR61, an Extracellular Matrix Signaling Protein, in Human Benign Prostatic Hyperplasia and Its Regulation by Lysophosphatidic Acid

    PubMed Central

    SAKAMOTO, SHINJI; YOKOYAMA, MASAHIRO; ZHANG, XIANGHUA; PRAKASH, KULKARNI; NAGAO, KAORI; HATANAKA, TAKASHI; GETZENBERG, ROBERT H.; KAKEHI, YOSHIYUKI

    2012-01-01

    Lysophosphatidic acid (LPA) is an endogenous lipid growth factor that is thought to play important roles in cell proliferation and antiapoptosis and therefore may have roles in the development and progression of benign prostatic hyperplasia (BPH). CYR61 (CCN1), on the other hand, is a growth factor-inducible immediate early gene that functions in cell proliferation, differentiation, and extracellular matrix synthesis. Here we show the close relationship between LPA-induced expression of CYR61 and prostate enlargement. CYR61 mRNA and protein were dramatically up-regulated by 18:1 LPA (oleoyl-LPA) within 1 and 2 h, respectively, in both stromal and epithelial prostatic cells. G protein-coupled receptors, i.e. Edg-2, Edg-4, and Edg-7, for LPA were also expressed in both stromal and epithelial prostatic cells. Furthermore, on DNA microarray analysis for normal and BPH patients, CYR61 was found to be related to the development and progression of BPH, regardless of symptoms. Although CYR61 mRNA was synthesized in hyperplastic epithelial cells, in many cases of BPH, CYR61 protein was detected in both the epithelial and stromal regions of BPH patient tissues. The functional contribution of CYR61 to prostatic cell growth was demonstrated by recombinant CYR61 protein and anti-CYR61 neutralizing antibodies, which inhibited CYR61-dependent cell spreading and significantly diminished cell proliferation, respectively. In conclusion, these data support the hypothesis that LPAs induce the expression of CYR61 by activating G protein-coupled receptors and that CYR61 acts as a secreted autocrine and/or paracrine mediator in stromal and epithelial hyperplasia, demonstrating the potential importance of this signaling mechanism in the disease. (Endocrinology 145: 2929–2940, 2004) PMID:14988385

  13. Lysophosphatidic acid-induced RhoA signaling and prolonged macrophage infiltration worsens fibrosis and fatty infiltration following rotator cuff tears.

    PubMed

    Davies, Michael R; Lee, Lawrence; Feeley, Brian T; Kim, Hubert T; Liu, Xuhui

    2017-07-01

    Previous studies have suggested that macrophage-mediated chronic inflammation is involved in the development of rotator cuff muscle atrophy and degeneration following massive tendon tears. Increased RhoA signaling has been reported in chronic muscle degeneration, such as muscular dystrophy. However, the role of RhoA signaling in macrophage infiltration and rotator muscle degeneration remains unknown. Using a previously established rat model of massive rotator cuff tears, we found RhoA signaling is upregulated in rotator cuff muscle following a massive tendon-nerve injury. This increase in RhoA expression is greatly potentiated by the administration of a potent RhoA activator, lysophosphatidic acid (LPA), and is accompanied by increased TNFα and TGF-β1 expression in rotator cuff muscle. Boosting RhoA signaling with LPA significantly worsened rotator cuff muscle atrophy, fibrosis, and fatty infiltration, accompanied with massive monocytic infiltration of rotator cuff muscles. Co-staining of RhoA and the tissue macrophage marker CD68 showed that CD68+ tissue macrophages are the dominant cell source of increased RhoA signaling in rotator cuff muscles after tendon tears. Taken together, our findings suggest that LPA-mediated RhoA signaling in injured muscle worsens the outcomes of atrophy, fibrosis, and fatty infiltration by increasing macrophage infiltraion in rotator cuff muscle. Clinically, inhibiting RhoA signaling may represent a future direction for developing new treatments to improve muscle quality following massive rotator cuff tears. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:1539-1547, 2017. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc.

  14. Lysophosphatidic Acid-induced ERK Activation and Chemotaxis in MC3T3-E1 Preosteoblasts are Independent of EGF Receptor Transactivation

    SciTech Connect

    Karagiosis, Sue A.; Chrisler, William B.; Bollinger, Nikki; Karin, Norman J.

    2009-06-01

    Growing evidence indicates that bone-forming osteoblasts and their progenitors are target cells for the lipid growth factor lysophosphatidic acid (LPA) which is produced by degranulating platelets at sites of injury. LPA is a potent inducer of bone cell migration, proliferation and survival in vitro and an attractive candidate to facilitate preosteoblast chemotaxis during skeletal regeneration in vivo, but the intracellular signaling pathways mediating the effects of this lipid on bone cells are not defined. In this study we measured the ability of LPA to stimulate extracellular signal-related kinase (ERK1/2) in MC3T3-E1 preosteoblastic cells and determined the contribution of this pathway to LPA-stimulated chemotaxis. LPA-treated cells exhibited a bimodal activation of ERK1/2 with maximal phosphorylation at 5 and 60 minutes. The kinetics of ERK1/2 phosphorylation were not coupled to Ras activation or LPA-induced elevations in cytosolic Ca2+. While LPA is coupled to the transactivation of the EGF receptor in many cell types, LPA-stimulated ERK1/2 activation in MC3T3-E1 cells was unaffected by inhibition of EGF receptor function. ERK isoforms rapidly accumulated at nuclear sites in LPA-treated cells, a process that was blocked if ERK1/2 phosphorylation was prevented with the MEK1 inhibitor U0126. Blocking ERK1/2 phosphorylation with U0126 also diminished MC3T3-E1 cell migration and altered the normal disassembly of LPA-induced stress fibers, while the inhibition of EGF receptor function had no effect on LPA-coupled preosteoblast motility. Our results identify ERK1/2 activation as a mediatora mediator of LPA-stimulated MC3T3-E1 cell migration that may be relevant to preosteoblast motility during bone repair in vivo.

  15. Lipid phosphate phosphatase inhibitors locally amplify lysophosphatidic acid LPA1 receptor signalling in rat brain cryosections without affecting global LPA degradation

    PubMed Central

    2012-01-01

    Background Lysophosphatidic acid (LPA) is a signalling phospholipid with multiple biological functions, mainly mediated through specific G protein-coupled receptors. Aberrant LPA signalling is being increasingly implicated in the pathology of common human diseases, such as arteriosclerosis and cancer. The lifetime of the signalling pool of LPA is controlled by the equilibrium between synthesizing and degradative enzymatic activity. In the current study, we have characterized these enzymatic pathways in rat brain by pharmacologically manipulating the enzymatic machinery required for LPA degradation. Results In rat brain cryosections, the lifetime of bioactive LPA was found to be controlled by Mg2+-independent, N-ethylmaleimide-insensitive phosphatase activity, attributed to lipid phosphate phosphatases (LPPs). Pharmacological inhibition of this LPP activity amplified LPA1 receptor signalling, as revealed using functional autoradiography. Although two LPP inhibitors, sodium orthovanadate and propranolol, locally amplified receptor responses, they did not affect global brain LPA phosphatase activity (also attributed to Mg2+-independent, N-ethylmaleimide-insensitive phosphatases), as confirmed by Pi determination and by LC/MS/MS. Interestingly, the phosphate analog, aluminium fluoride (AlFx-) not only irreversibly inhibited LPP activity thereby potentiating LPA1 receptor responses, but also totally prevented LPA degradation, however this latter effect was not essential in order to observe AlFx--dependent potentiation of receptor signalling. Conclusions We conclude that vanadate- and propranolol-sensitive LPP activity locally guards the signalling pool of LPA whereas the majority of brain LPA phosphatase activity is attributed to LPP-like enzymatic activity which, like LPP activity, is sensitive to AlFx- but resistant to the LPP inhibitors, vanadate and propranolol. PMID:22686545

  16. Preparation of functional human lysophosphatidic acid receptor 2 using a P9(∗) expression system and an amphipathic polymer and investigation of its in vitro binding preference to Gα proteins.

    PubMed

    Han, Seong-Gu; Baek, Seung-Il; Son, Tae Jin; Lee, Hyeongjin; Kim, Nam Hyuk; Yu, Yeon Gyu

    2017-05-20

    Human lysophosphatidic acid receptor 2 (LPA2), a member of the G-protein coupled receptor family, mediates lysophosphatidic acid (LPA)-dependent signaling by recruiting various G proteins. Particularly, it is directly implicated in the progression of colorectal and ovarian cancer through G protein signaling cascades. To investigate the biochemical binding properties of LPA2 against various alpha subunits of G protein (Gα), a functional recombinant LPA2 was overexpressed in E. coli membrane with a P9(∗) expression system, and the purified protein was stabilized with an amphipathic polymer that had been synthesized by coupling octylamine, glucosamine, and diethyl aminoproylamine at the carboxylic groups of poly-γ-glutamic acid. The purified LPA2 stabilized with the amphipathic polymer showed selective binding activity to the various Gα proteins as well as agonist-dependent dissociation from Gαi3. Understanding the binding properties of LPA2 against various Gα proteins advances the understanding of downstream signaling cascades of LPA2. The functional LPA2 prepared using a P9(∗) expression system and an amphipathic polymer could also facilitate the development of LPA2-targeting drugs. Copyright © 2017 Elsevier Inc. All rights reserved.

  17. Autotaxin is released from adipocytes, catalyzes lysophosphatidic acid synthesis, and activates preadipocyte proliferation. Up-regulated expression with adipocyte differentiation and obesity.

    PubMed

    Ferry, Gilles; Tellier, Edwige; Try, Anne; Grés, Sandra; Naime, Isabelle; Simon, Marie Françoise; Rodriguez, Marianne; Boucher, Jérémie; Tack, Ivan; Gesta, Stéphane; Chomarat, Pascale; Dieu, Marc; Raes, Martine; Galizzi, Jean Pierre; Valet, Philippe; Boutin, Jean A; Saulnier-Blache, Jean Sébastien

    2003-05-16

    Our group has recently demonstrated (Gesta, S., Simon, M., Rey, A., Sibrac, D., Girard, A., Lafontan, M., Valet, P., and Saulnier-Blache, J. S. (2002) J. Lipid Res. 43, 904-910) the presence, in adipocyte conditioned-medium, of a soluble lysophospholipase d-activity (LPLDact) involved in synthesis of the bioactive phospholipid lysophosphatidic acid (LPA). In the present report, LPLDact was purified from 3T3F442A adipocyte-conditioned medium and identified as the type II ecto-nucleotide pyrophosphatase phosphodiesterase, autotaxin (ATX). A unique ATX cDNA was cloned from 3T3F442A adipocytes, and its recombinant expression in COS-7 cells led to extracellular release of LPLDact. ATX mRNA expression was highly up-regulated during adipocyte differentiation of 3T3F442A-preadipocytes. This up-regulation was paralleled by the ability of newly differentiated adipocytes to release LPLDact and LPA. Differentiation-dependent up-regulation of ATX expression was also observed in a primary culture of mouse preadipocytes. Treatment of 3T3F442A-preadipocytes with concentrated conditioned medium from ATX-expressing COS-7 cells led to an increase in cell number as compared with concentrated conditioned medium from ATX non-expressing COS-7 cells. The specific effect of ATX on preadipocyte proliferation was completely suppressed by co-treatment with a LPA-hydrolyzing phospholipase, phospholipase B. Finally, ATX expression was found in mature adipocytes isolated from mouse adipose tissue and was substantially increased in genetically obese-diabetic db/db mice when compared with their lean siblings. In conclusion, the present work shows that ATX is responsible for the LPLDact released by adipocytes and exerts a paracrine control on preadipocyte growth via an LPA-dependent mechanism. Up-regulations of ATX expression with adipocyte differentiation and genetic obesity suggest a possible involvement of this released protein in the development of adipose tissue and obesity

  18. Different signaling pathway between sphingosine-1-phosphate and lysophosphatidic acid in Xenopus oocytes: functional coupling of the sphingosine-1-phosphate receptor to PLC-xbeta in Xenopus oocytes.

    PubMed

    Noh, S J; Kim, M J; Shim, S; Han, J K

    1998-08-01

    In Xenopus oocytes, both sphingosine-1-phosphate (S1P) and lysophosphatidic acid (LPA) activate Ca2+-dependent oscillatory Cl- currents by acting through membrane-bound receptors. External application of 50 microM S1P elicited a long-lasting oscillatory current that continued over 30 min from the beginning of oscillation, with 300 nA (n = 11) as a usual maximum peak of current, whereas 1-microM LPA treatment showed only transiently oscillating but more vigorous current responses, with 2,800 nA (n = 18) as a maximum peak amplitude. Both phospholipid-induced Ca2+-dependent Cl- currents were observed in the absence of extracellular Ca2+, were blocked by intracellular injection of the Ca2+ chelator, EGTA, and could not be elicited by treatment with thapsigargin, an inhibitor of endoplasmic reticulum (ER) Ca2+ ATPase. Intracellular Ca2+ release appeared to be from inositol 1,4,5-trisphosphate (IP3)-sensitive Ca2+ store, because Cl- currents were blocked by heparin injection. Pretreatment with the aminosteroid, U-73122, an inhibitor of G protein-mediated phospholipase C (PLC) activation, to oocytes inhibited the current responses evoked both by S1P and LPA. However, when they were injected with 10 ng of antisense oligonucleotide (AS-ODN) against Xenopus phospholipase C (PLC-xbeta), oocytes could not respond to S1P application, whereas they responded normally to LPA, indicating that the S1P signaling pathway goes through PLC-xbeta, whereas LPA signaling goes through another unknown PLC. To determine the types of G proteins involved, we introduced AS-ODNs against four types of G-protein alpha subunits that were identified in Xenopus laevis; G(q)alpha, G11alpha, G0alpha, and G(i1)alpha. Among AS-ODNs against the G alphas tested, AS-G(q)alpha and AS-G(i1)alpha to S1P and AS-G(q)alpha and AS-G11alpha to LPA specifically reduced current responses, respectively, to about 20-30% of controls. These results demonstrate that LPA and S1P, although they have similar structural

  19. Comparison of total plasma lysophosphatidic acid and serum CA-125 as a tumor marker in the diagnosis and follow-up of patients with epithelial ovarian cancer

    PubMed Central

    Barbaros, Merve; Baykara, Elif; Guralp, Onur; Cengiz, Salih; Demirkiran, Fuat; Sanioglu, Cevdet; Arvas, Macit

    2010-01-01

    Objective To evaluate the role of lysophosphatidic acid (LPA) as a tumor marker in diagnosis and follow-up of patients with epithelial ovarian cancer. Methods Eighty-seven epithelial ovarian cancer patients, 74 benign ovarian tumor patients, and 50 healthy women were enrolled in the study. Twenty-nine of 87 epithelial ovarian cancer patients were followed up for 6 cycles of paclitaxel-carboplatin chemotherapy. CA-125 and total plasma LPA levels were measured preoperatively and before each chemotherapy cycle. Results Preoperative total plasma LPA and serum CA-125 levels were significantly higher in patients with epithelial ovarian cancer compared to patients with benign ovarian tumors and healthy women. Cut-off value for LPA was determined as 1.3 µmol/L and sensitivity, specificity, positive predictive value and negative predictive value were 95%, 92%, 95% and 92%, respectively. Mean total plasma LPA level of 29 patients who received chemotherapy was 7.21±6.63 µmol/L preoperatively and 6.84±6.34 µmol/L, 6.34±5.92 µmol/L, 6.14±5.79 µmol/L, 5.86±5.68 µmol/L, 5.23±5.11 µmol/L and 5.21±5.32 µmol/L in measurements held just before the 1st, 2nd, 3rd, 4th, 5th and 6th chemotherapy cycles, respectively (ANOVA, p=0.832). Total plasma LPA levels decreased slightly with chemotherapy administration and there was a weak negative correlation (Spearman, rs=-0.151, p=0.034), compared to a significant negative correlation in CA-125 (Spearman, rs=-0.596, p<0.001). Conclusion LPA is a better biomarker for diagnosis of epithelial ovarian cancer compared to CA-125. However, measurement of total plasma LPA levels during chemotherapy administration have no superiority to the serum CA-125 levels. PMID:21278887

  20. Regulation of gene expression and subcellular protein distribution in MLO-Y4 osteocytic cells by lysophosphatidic acid: Relevance to dendrite outgrowth.

    SciTech Connect

    Waters, Katrina M.; Jacobs, Jon M.; Gritsenko, Marina A.; Karin, Norman J.

    2011-02-26

    Osteoblastic and osteocytic cells are highly responsive to the lipid growth factor lysophosphatidic acid (LPA) but the mechanisms by which LPA alters bone cell functions are largely unknown. A major effect of LPA on osteocytic cells is the stimulation of dendrite membrane outgrowth, a process that we predicted to require changes in gene expression and protein distribution. We employed DNA microarrays for global transcriptional profiling of MLO-Y4 osteocytic cells grown for 6 and 24h in the presence or absence of LPA. We identified 932 transcripts that displayed statistically significant changes in abundance of at least 1.25-fold in response to LPA treatment. Gene ontology (GO) analysis revealed that the regulated gene products were linked to diverse cellular processes, including DNA repair, response to unfolded protein, ossification, protein-RNA complex assembly, and amine biosynthesis. Gene products associated with the regulation of actin microfilament dynamics displayed the most robust expression changes, and LPA-induced dendritogenesis in vitro was blocked by the stress fiber inhibitor cytochalasin D. Mass spectrometry-based proteomic analysis of MLO-Y4 cells revealed significant LPA-induced changes in the abundance of 284 proteins at 6h and 844 proteins at 24h. GO analysis of the proteomic data linked the effects of LPA to cell processes that control of protein distribution and membrane outgrowth, including protein localization, protein complex assembly, Golgi vesicle transport, cytoskeleton-dependent transport, and membrane invagination/endocytosis. Dendrites were isolated from LPA-treated MLO-Y4 cells and subjected to proteomic analysis to quantitatively assess the subcellular distribution of proteins. Sets of 129 and 36 proteins were enriched in the dendrite fraction as compared to whole cells after 6h and 24h of LPA exposure, respectively. Protein markers indicated that membranous organelles were largely excluded from the dendrites. Highly represented among

  1. A two-helix motif positions the active site of lysophosphatidic acid acyltransferase for catalysis within the membrane bilayer

    PubMed Central

    Robertson, Rosanna M.; Yao, Jiangwei; Gajewski, Stefan; Kumar, Gyanendra; Martin, Erik W.; Rock, Charles O.; White, Stephen W.

    2017-01-01

    Phosphatidic acid is the central intermediate in membrane phospholipid synthesis and is generated by two acyltransferases in a pathway conserved in all life forms. The second step in this pathway is catalyzed by 1-acyl-sn-glycero-3-phosphate acyltransferase, called PlsC in bacteria. The crystal structure of PlsC from Thermotoga maritima reveals an unusual hydrophobic/aromatic N-terminal two-helix motif linked to an acyltransferase αβ domain that contains the catalytic HX4D motif. PlsC dictates the acyl chain composition of the 2-position of phospholipids, and the acyl chain selectivity ‘ruler’ is an appropriately placed and closed hydrophobic tunnel. This was confirmed by site-directed mutagenesis and membrane composition analysis of Escherichia coli cells expressing the mutated proteins. MD simulations reveal that the two-helix motif represents a novel substructure that firmly anchors the protein to one leaflet of the membrane. This binding mode allows the PlsC active site to acylate lysophospholipids within the membrane bilayer using soluble acyl donors. PMID:28714993

  2. A two-helix motif positions the lysophosphatidic acid acyltransferase active site for catalysis within the membrane bilayer.

    PubMed

    Robertson, Rosanna M; Yao, Jiangwei; Gajewski, Stefan; Kumar, Gyanendra; Martin, Erik W; Rock, Charles O; White, Stephen W

    2017-08-01

    Phosphatidic acid (PA), the central intermediate in membrane phospholipid synthesis, is generated by two acyltransferases in a pathway conserved in all life forms. The second step in this pathway is catalyzed by 1-acyl-sn-glycerol-3-phosphate acyltransferase, called PlsC in bacteria. Here we present the crystal structure of PlsC from Thermotoga maritima, revealing an unusual hydrophobic/aromatic N-terminal two-helix motif linked to an acyltransferase αβ-domain that contains the catalytic HX4D motif. PlsC dictates the acyl chain composition of the 2-position of phospholipids, and the acyl chain selectivity 'ruler' is an appropriately placed and closed hydrophobic tunnel. We confirmed this by site-directed mutagenesis and membrane composition analysis of Escherichia coli cells that expressed mutant PlsC. Molecular dynamics (MD) simulations showed that the two-helix motif represents a novel substructure that firmly anchors the protein to one leaflet of the membrane. This binding mode allows the PlsC active site to acylate lysophospholipids within the membrane bilayer by using soluble acyl donors.

  3. Lysophosphatidic acid (LPA) signalling in cell migration and cancer invasion: a focussed review and analysis of LPA receptor gene expression on the basis of more than 1700 cancer microarrays.

    PubMed

    Willier, Semjon; Butt, Elke; Grunewald, Thomas G P

    2013-08-01

    Lysophosphatidic acid (LPA) is a ubiquitously present signalling molecule involved in diverse cellular processes such as cell migration, proliferation and differentiation. LPA acts as an autocrine and/or paracrine signalling molecule via different G-protein-coupled LPA receptors (LPARs) that trigger a broad range of intracellular signalling cascades, especially the RHOA pathway. Mounting evidence suggests a crucial role of the LPA/LPAR-axis in cancer cell metastasis and promising studies are underway to investigate the therapeutic potential of LPAR-antagonists. This review summarises current knowledge on how LPA promotes cytoskeletal remodelling to enhance the migratory and invasive properties of cells, which may ultimately contribute to cancer metastasis. Furthermore, we provide comprehensive transcriptome analyses of published microarrays of more than 350 normal tissues and more than 1700 malignant tissues to define the expression signatures of LPARs and the LPA-generating enzymes autotaxin (ATX) and lipase member 1 (LIPI). These analyses demonstrate that ATX is highly expressed in a variety of carcinomas and sarcomas, whereas LIPI is almost exclusively overexpressed in highly aggressive Ewing's sarcomas, which underscores the potential contribution of LPA in metastatic disease. In addition, these analyses show that different cancer entities display distinct expression signatures of LPARs that distinguish them from one another. Finally, we discuss current approaches to specifically target the LPA/LPAR circuits in experimental cancer therapy. © 2013 Société Française des Microscopies and Société de Biologie Cellulaire de France. Published by John Wiley & Sons Ltd.

  4. RhoA Kinase (Rock) and p90 Ribosomal S6 Kinase (p90Rsk) phosphorylation of the sodium hydrogen exchanger (NHE1) is required for lysophosphatidic acid-induced transport, cytoskeletal organization and migration.

    PubMed

    Wallert, Mark A; Hammes, Daniel; Nguyen, Tony; Kiefer, Lea; Berthelsen, Nick; Kern, Andrew; Anderson-Tiege, Kristina; Shabb, John B; Muhonen, Wallace W; Grove, Bryon D; Provost, Joseph J

    2015-03-01

    The sodium hydrogen exchanger isoform one (NHE1) plays a critical role coordinating asymmetric events at the leading edge of migrating cells and is regulated by a number of phosphorylation events influencing both the ion transport and cytoskeletal anchoring required for directed migration. Lysophosphatidic acid (LPA) activation of RhoA kinase (Rock) and the Ras-ERK growth factor pathway induces cytoskeletal reorganization, activates NHE1 and induces an increase in cell motility. We report that both Rock I and II stoichiometrically phosphorylate NHE1 at threonine 653 in vitro using mass spectrometry and reconstituted kinase assays. In fibroblasts expressing NHE1 alanine mutants for either Rock (T653A) or ribosomal S6 kinase (Rsk; S703A) we show that each site is partially responsible for the LPA-induced increase in transport activity while NHE1 phosphorylation by either Rock or Rsk at their respective site is sufficient for LPA stimulated stress fiber formation and migration. Furthermore, mutation of either T653 or S703 leads to a higher basal pH level and a significantly higher proliferation rate. Our results identify the direct phosphorylation of NHE1 by Rock and suggest that both RhoA and Ras pathways mediate NHE1-dependent ion transport and migration in fibroblasts.

  5. Lysophosphatidic Acid Increases Proximal Tubule Cell Secretion of Profibrotic Cytokines PDGF-B and CTGF through LPA2- and Gαq-Mediated Rho and αvβ6 Integrin-Dependent Activation of TGF-β

    PubMed Central

    Geng, Hui; Lan, Rongpei; Singha, Prajjal K.; Gilchrist, Annette; Weinreb, Paul H.; Violette, Shelia M.; Weinberg, Joel M.; Saikumar, Pothana; Venkatachalam, Manjeri A.

    2013-01-01

    After ischemia-reperfusion injury (IRI), kidney tubules show activated transforming growth factor β (TGF-β) signaling and increased expression of profibrotic peptides, platelet-derived growth factor-B (PDGF-B) and connective tissue growth factor (CTGF). If tubule repair after IRI is incomplete, sustained paracrine activity of these peptides can activate interstitial fibroblast progenitors and cause fibrosis. We show that lysophosphatidic acid (LPA), a ubiquitous phospholipid that is increased at sites of injury and inflammation, signals through LPA2 receptors and Gαq proteins of cultured proximal tubule cells to transactivate latent TGF-β in a Rho/Rho-kinase and αvβ6 integrin-dependent manner. Active TGF-β peptide then initiates signaling to increase the production and secretion of PDGF-B and CTGF. In a rat model of IRI, increased TGF-β signaling that was initiated early during reperfusion did not subside during recovery, but progressively increased, causing tubulointerstitial fibrosis. This was accompanied by correspondingly increased LPA2 and β6 integrin proteins and elevated tubule expression of TGF-β1, together with PDGF-B and CTGF. Treatment with a pharmacological TGF-β type I receptor antagonist suppressed TGF-β signaling, decreased the expression of β6 integrin, PDGF-B, and CTGF, and ameliorated fibrosis. We suggest that LPA-initiated autocrine signaling is a potentially important mechanism that gives rise to paracrine profibrotic signaling in injured kidney tubule cells. PMID:22885106

  6. Protein kinase C alpha-CARMA3 signaling axis links Ras to NF-kappa B for lysophosphatidic acid-induced urokinase plasminogen activator expression in ovarian cancer cells.

    PubMed

    Mahanivong, C; Chen, H M; Yee, S W; Pan, Z K; Dong, Z; Huang, S

    2008-02-21

    We reported previously that a signaling pathway consisting of G(i)-Ras-NF-kappaB mediates lysophosphatidic acid (LPA)-induced urokinase plasminogen activator (uPA) upregulation in ovarian cancer cells. However, it is not clear what signaling components link Ras to nuclear factor (NF)-kappaB for this LPA-induced event. In the present study, we found that treatment of protein kinase C (PKC) inhibitors including conventional PKC (cPKC) inhibitor Gö6976 abolished LPA-induced uPA upregulation in ovarian cancer cell lines tested, indicating the importance of cPKC activity in this LPA-induced event. Indeed, LPA stimulation led to the activation of PKCalpha and Ras-PKCalpha interaction. Although constitutively active mutants of PKCalpha (a cPKC), PKCtheta (a novel PKC (nPKC)) and PKCzeta (an atypical PKC (aPKC)) were all able to activate NF-kappaB and upregulate uPA expression, only dominant-negative PKCalpha mutant attenuated LPA-induced NF-kappaB activation and uPA upregulation. These results suggest that PKCalpha, rather than PKC isoforms in other PKC classes, participates in LPA-induced NF-kappaB activation and uPA upregulation in ovarian cancer cells. To determine the signaling components downstream of PKCalpha mediating LPA-induced uPA upregulation, we showed that forced expression of dominant-negative CARMA3 or silencing CARMA3, Bcl10 and MALT1 with specific siRNAs diminished these LPA-induced events. Furthermore, we demonstrated that PKCalpha/CARMA3 signaling axis is important in LPA-induced ovarian cancer cell in vitro invasion.

  7. Antidepressants activate the lysophosphatidic acid receptor LPA(1) to induce insulin-like growth factor-I receptor transactivation, stimulation of ERK1/2 signaling and cell proliferation in CHO-K1 fibroblasts.

    PubMed

    Olianas, Maria C; Dedoni, Simona; Onali, Pierluigi

    2015-06-15

    Different lines of evidence indicate that the lysophosphatidic acid (LPA) receptor LPA1 is involved in neurogenesis, synaptic plasticity and anxiety-related behavior, but little is known on whether this receptor can be targeted by neuropsychopharmacological agents. The present study investigated the effects of different antidepressants on LPA1 signaling. We found that in Chinese hamster ovary (CHO)-K1 fibroblasts expressing endogenous LPA1 tricyclic and tetracyclic antidepressants and fluoxetine induced the phosphorylation of extracellular signal-regulated kinase1/2 (ERK1/2) and CREB. This response was antagonized by either LPA1 blockade with Ki16425 and AM966 or knocking down LPA1 with siRNA. Antidepressants induced ERK1/2 phosphorylation in human embryonic kidney (HEK)-293 cells overexpressing LPA1, but not in wild-type cells. In PathHunter™ assay measuring receptor-β-arrestin interaction, amitriptyline, mianserin and fluoxetine failed to induce activation of LPA2 and LPA3 stably expressed in CHO-K1 cells. ERK1/2 stimulation by antidepressants and LPA was suppressed by pertussis toxin and inhibition of Src, phosphatidylinositol-3 kinase and insulin-like growth factor-I receptor (IGF-IR) activities. Antidepressants and LPA induced tyrosine phosphorylation of IGF-IR and insulin receptor-substrate-1 through LPA1 and Src. Prolonged exposure of CHO-K1 fibroblasts to either mianserin, mirtazapine or LPA enhanced cell proliferation as indicated by increased [(3)H]-thymidine incorporation and Ki-67 immunofluorescence. This effect was inhibited by blockade of LPA1- and ERK1/2 activity. These data provide evidence that different antidepressants induce LPA1 activation, leading to receptor tyrosine kinase transactivation, stimulation of ERK1/2 signaling and enhanced cell proliferation. Copyright © 2015 Elsevier Inc. All rights reserved.

  8. Apicoplast-Localized Lysophosphatidic Acid Precursor Assembly Is Required for Bulk Phospholipid Synthesis in Toxoplasma gondii and Relies on an Algal/Plant-Like Glycerol 3-Phosphate Acyltransferase

    PubMed Central

    Callahan, Damien L.; Dubois, David; van Dooren, Giel G.; Shears, Melanie J.; Cesbron-Delauw, Marie-France; Maréchal, Eric; McConville, Malcolm J.; McFadden, Geoffrey I.; Yamaryo-Botté, Yoshiki; Botté, Cyrille Y.

    2016-01-01

    Most apicomplexan parasites possess a non-photosynthetic plastid (the apicoplast), which harbors enzymes for a number of metabolic pathways, including a prokaryotic type II fatty acid synthesis (FASII) pathway. In Toxoplasma gondii, the causative agent of toxoplasmosis, the FASII pathway is essential for parasite growth and infectivity. However, little is known about the fate of fatty acids synthesized by FASII. In this study, we have investigated the function of a plant-like glycerol 3-phosphate acyltransferase (TgATS1) that localizes to the T. gondii apicoplast. Knock-down of TgATS1 resulted in significantly reduced incorporation of FASII-synthesized fatty acids into phosphatidic acid and downstream phospholipids and a severe defect in intracellular parasite replication and survival. Lipidomic analysis demonstrated that lipid precursors are made in, and exported from, the apicoplast for de novo biosynthesis of bulk phospholipids. This study reveals that the apicoplast-located FASII and ATS1, which are primarily used to generate plastid galactolipids in plants and algae, instead generate bulk phospholipids for membrane biogenesis in T. gondii. PMID:27490259

  9. Kinetic and biochemical correlation between sustained p44ERK1 (44 kDa extracellular signal-regulated kinase 1) activation and lysophosphatidic acid-stimulated DNA synthesis in Rat-1 cells.

    PubMed Central

    Cook, S J; McCormick, F

    1996-01-01

    Rat-1 fibroblasts were used to study the role of the sustained activation of extracellular signal-regulated kinase 1 (ERK1) in lysophosphatidic acid (LPA)-stimulated mitogenic signalling. Mitogenic doses of LPA, like serum, stimulated biphasic, sustained, ERK activation that persisted towards the G1/S boundary. The EC50 for LPA-stimulated ERK activation after 10 min, the time of peak response, was 2 orders of magnitude to the left of that for the sustained response after 3 h or that for DNA synthesis after 22 h, with the result that non-mitogenic doses stimulated a maximal peak response but no second phase. To complement these studies, we examined the role of different signal pathways in regulating the sustained and acute phases of ERK activation using defined biochemical inhibitors and mimetics. Activation of protein kinase C and Ca2+ fluxes played a minor and transient role in regulation of ERK1 activity by LPA in Rat-1 cells. Sustained ERK1 activation stimulated by LPA was completely inhibited by pertussis toxin, whereas the early peak response was only partly affected; this is correlated with the specific inhibition of LPA-stimulated DNA synthesis by pertussis toxin. The selective tyrosine kinase inhibitor herbimycin A completely inhibited sustained ERK1 activation by LPA but, again, the early phase of the response was only partially inhibited. In addition, low doses of staurosporine inhibited ERK1 activation by LPA. The effects of herbimycin A and staurosporine were selective for the response to LPA but did not affect that to epidermal growth factor. The results suggest a strong correlation between sustained ERK1 activation and DNA synthesis in LPA-stimulated Rat-1 cells. Furthermore, the two discrete phases of ERK activation by LPA are regulated by a combination of at least two different signalling pathways; the sustained activation of ERK1 in Rat-1 cells proceeds via a G1- or Gzero-mediated pathway which may also involve a tyrosine kinase. PMID:8947493

  10. Expression of factors involved in apoptosis and cell survival is correlated with enzymes synthesizing lysophosphatidic acid and its receptors in granulosa cells originating from different types of bovine ovarian follicles.

    PubMed

    Sinderewicz, Emilia; Grycmacher, Katarzyna; Boruszewska, Dorota; Kowalczyk-Zięba, Ilona; Staszkiewicz, Joanna; Ślężak, Tomasz; Woclawek-Potocka, Izabela

    2017-09-06

    Lysophosphatidic acid (LPA) regulates reproductive processes in the cow. Ovarian granulosa cells play a pivotal role in follicle growth and development. Nevertheless, the role of LPA in the local regulation of granulosa cell function in different follicle categories in the bovine ovary has not been investigated. Ovarian follicles were divided into healthy, transitional and atretic categories. The expression levels of AX, PLA2, LPARs and factors involved in apoptosis and cell survival processes in granulosa cells in different types of follicles were measured by real-time PCR. The correlations between the expression levels of AX, PLA2, LPARs and the examined factors were measured. The immunolocalization of AX, PLA2 and LPARs in different ovarian follicles was examined by immunohistochemistry. Statistical analyses were conducted in GraphPad using a one-way ANOVA followed by the Kruskal-Wallis multiple comparison test or a correlation analysis followed by Pearson's test. The expression levels of AX, PLA2 and LPARs, with the major role of LPAR2 and PLA2, were found in the granulosa cells originating from different follicle types. The expression levels of the factors involved in cell apoptosis (TNFα and its receptors, FAS, FASL, CASP3, CASP8, β-glycan, and DRAK2) were significantly higher in the granulosa cells of the atretic follicles compared to the healthy follicles. A number of correlations between LPARs, AX, PLA2 and factors associated with apoptosis were observed in the atretic but not in the healthy follicles. A greater expression of the factors involved in differentiation and proliferation in the granulosa cells (DICE1 and SOX2) was found in the healthy follicles in comparison with the atretic. A number of correlations between LPARs, AX, PLA2 and the factors associated with cell survival were observed in the healthy but not in the atretic follicles. Granulosa cells are the target of LPA action and the source of LPA synthesis in the bovine ovarian follicle. We

  11. Identification of heparin-binding EGF-like growth factor (HB-EGF) as a biomarker for lysophosphatidic acid receptor type 1 (LPA1) activation in human breast and prostate cancers.

    PubMed

    David, Marion; Sahay, Debashish; Mege, Florence; Descotes, Françoise; Leblanc, Raphaël; Ribeiro, Johnny; Clézardin, Philippe; Peyruchaud, Olivier

    2014-01-01

    Lysophosphatidic acid (LPA) is a natural bioactive lipid with growth factor-like functions due to activation of a series of six G protein-coupled receptors (LPA₁₋₆). LPA receptor type 1 (LPA₁) signaling influences the pathophysiology of many diseases including cancer, obesity, rheumatoid arthritis, as well as lung, liver and kidney fibrosis. Therefore, LPA₁ is an attractive therapeutic target. However, most mammalian cells co-express multiple LPA receptors whose co-activation impairs the validation of target inhibition in patients because of missing LPA receptor-specific biomarkers. LPA₁ is known to induce IL-6 and IL-8 secretion, as also do LPA₂ and LPA₃. In this work, we first determined the LPA induced early-gene expression profile in three unrelated human cancer cell lines expressing different patterns of LPA receptors (PC3: LPA₁,₂,₆; MDA-MB-231: LPA1,2; MCF-7: LPA₂,₆). Among the set of genes upregulated by LPA only in LPA₁-expressing cells, we validated by QPCR and ELISA that upregulation of heparin-binding EGF-like growth factor (HB-EGF) was inhibited by LPA₁-₃ antagonists (Ki16425, Debio0719). Upregulation and downregulation of HB-EGF mRNA was confirmed in vitro in human MDA-B02 breast cancer cells stably overexpressing LPA₁ (MDA-B02/LPA₁) and downregulated for LPA₁ (MDA-B02/shLPA1), respectively. At a clinical level, we quantified the expression of LPA₁ and HB-EGF by QPCR in primary tumors of a cohort of 234 breast cancer patients and found a significantly higher expression of HB-EGF in breast tumors expressing high levels of LPA₁. We also generated human xenograph prostate tumors in mice injected with PC3 cells and found that a five-day treatment with Ki16425 significantly decreased both HB-EGF mRNA expression at the primary tumor site and circulating human HB-EGF concentrations in serum. All together our results demonstrate that HB-EGF is a new and relevant biomarker with potentially high value in quantifying LPA

  12. During Hepatitis C Virus (HCV) Infection and HCV-HIV Coinfection, an Elevated Plasma Level of Autotaxin Is Associated With Lysophosphatidic Acid and Markers of Immune Activation That Normalize During Interferon-Free HCV Therapy.

    PubMed

    Kostadinova, Lenche; Shive, Carey L; Judge, Chelsey; Zebrowski, Elizabeth; Compan, Anita; Rife, Kelsey; Hirsch, Amy; Falck-Ytter, Yngve; Schlatzer, Daniela M; Li, Xiaolin; Chance, Mark R; Rodriguez, Benigno; Popkin, Daniel L; Anthony, Donald D

    2016-11-01

     Immune activation predicts morbidity during hepatitis C virus (HCV) infection and human immunodeficiency virus (HIV) infection, although mechanisms underlying immune activation are unclear. Plasma levels of autotaxin and its enzymatic product, lysophosphatidic acid (LPA), are elevated during HCV infection, and LPA activates immunocytes, but whether this contributes to immune activation is unknown.  We evaluated plasma levels of autotaxin, interleukin 6 (IL-6), soluble CD14 (sCD14), soluble CD163 (sCD163), and Mac2 binding protein (Mac2BP) during HCV infection, HIV infection, and HCV-HIV coinfection, as well as in uninfected controls, before and after HIV antiretroviral therapy (ART) initiation and during interferon-free HCV therapy.  We observed greater plasma autotaxin levels in HCV-infected and HCV-HIV-coinfected participants, compared with uninfected participants, primarily those with a higher ratio of aspartate aminotransferase level to platelet count. Autotaxin levels correlated with IL-6, sCD14, sCD163, Mac2BP, and LPA levels in HCV-infected participants and with Mac2BP levels in HCV-HIV-coinfected participants, while in HIV-infected individuals, sCD14 levels correlated with Mac2BP levels. Autotaxin, LPA, and sCD14 levels normalized, while sCD163 and Mac2BP levels partially normalized within 6 months of starting interferon-free HCV therapy. sCD163 and IL-6 levels normalized within 6 months of starting ART for HIV infection. In vitro, LPA activated monocytes.  These data indicate that elevated levels of autotaxin and soluble markers of immune activation during HCV infection are partially reversible within 6 months of initiating interferon-free HCV treatment and that autotaxin may be causally linked to immune activation during HCV infection and HCV-HIV coinfection. Published by Oxford University Press for the Infectious Diseases Society of America 2016. This work is written by (a) US Government employee(s) and is in the public domain in the US.

  13. Participation of analogues of lysophosphatidic acid (LPA): oleoyl-sn-glycero-3-phosphate (L-alpha-LPA) and 1-oleoyl-2-O-methyl-rac-glycerophosphothionate (OMPT) in uterine smooth muscle contractility of the pregnant pigs.

    PubMed

    Markiewicz, W; Kamińska, K; Bogacki, M; Maślanka, T; Jaroszewski, J

    2012-01-01

    Recent studies show that a representative of phospholipids, namely lysophosphatidic acid (LPA) and its receptors (LPA1.3) play a significant role in the reproductive processes, i. a, in the modulation of the uterine contractility. The participation of LPA3 in the reproductive processes has been revealed in mice and has not been studied in gilts. Therefore, in the present study we investigated the role/action of LPA and its receptors LPA1, LPA2 and LPA3 on the contraction activity in the porcine uterus. The study was conducted on an experimental model in which the pig uterus consisted of the one whole uterine horn and a part of the second horn, both connected with the uterine corpus. Uterine strips consisting of the endometrium with the myometrium (ENDO/MYO) and myometrium (MYO) alone were collected on days 12-14 of the estrous cycle (control group; n = 5) or pregnancy (experimental group; n = 5). Two analogues of LPA at increasing doses were used: oleoyl-sn-glycero-3-phosphate (L-alpha-LPA, a selective agonist of LPA1 and LPA2 receptors; 10(-7) M; 10(-6) M and 10(-5) M) and 1-oleoyl-2-O-methyl-rac-glycerophosphothionate (OMPT, a selective agonist of LPA3 receptor; 68 nM; 136 nM and 680 nM). L-alpha-LPA caused an increase in the contraction tension, amplitude and frequency of ENDO/MYO from the uterine horn with the developing embryos. This effect was not observed in MYO in both groups examined. In the ENDO/MYO strips of the uterine horn with developing embryos, OMPT significantly increased the contraction tension at the highest dose (680 nM) and amplitude at all doses examined, while frequency of contractions was decreased at doses of 136 nM and 680 nM. In the MYO strips of the uterine horn with embryos a significant increase in the contraction tension and amplitude after the highest dose of OMPT was observed. The results obtained imply the important role of receptors LPA1, LPA2 and LPA3 in the contraction activity of the porcine uterus during early pregnancy.

  14. Lysophosphatidic Acid Acyltransferase from Coconut Endosperm Mediates the Insertion of Laurate at the sn-2 Position of Triacylglycerols in Lauric Rapeseed Oil and Can Increase Total Laurate Levels

    PubMed Central

    Knutzon, Deborah S.; Hayes, Thomas R.; Wyrick, Annette; Xiong, Hui; Maelor Davies, H.; Voelker, Toni A.

    1999-01-01

    Expression of a California bay laurel (Umbellularia californica) 12:0-acyl-carrier protein thioesterase, bay thioesterase (BTE), in developing seeds of oilseed rape (Brassica napus) led to the production of oils containing up to 50% laurate. In these BTE oils, laurate is found almost exclusively at the sn-1 and sn-3 positions of the triacylglycerols (T.A. Voelker, T.R. Hayes, A.C. Cranmer, H.M. Davies [1996] Plant J 9: 229–241). Coexpression of a coconut (Cocos nucifera) 12:0-coenzyme A-preferring lysophosphatitic acid acyltransferase (D.S. Knutzon, K.D. Lardizabal, J.S. Nelsen, J.L. Bleibaum, H.M. Davies, J.G. Metz [1995] Plant Physiol 109: 999–1006) in BTE oilseed rape seeds facilitates efficient laurate deposition at the sn-2 position, resulting in the acccumulation of trilaurin. The introduction of the coconut protein into BTE oilseed rape lines with laurate above 50 mol % further increases total laurate levels. PMID:10398708

  15. Tannic acid inhibits Staphylococcus aureus surface colonization in an IsaA-dependent manner.

    PubMed

    Payne, David E; Martin, Nicholas R; Parzych, Katherine R; Rickard, Alex H; Underwood, Adam; Boles, Blaise R

    2013-02-01

    Staphylococcus aureus is a human commensal and pathogen that is capable of forming biofilms on a variety of host tissues and implanted medical devices. Biofilm-associated infections resist antimicrobial chemotherapy and attack from the host immune system, making these infections particularly difficult to treat. In order to gain insight into environmental conditions that influence S. aureus biofilm development, we screened a library of small molecules for the ability to inhibit S. aureus biofilm formation. This led to the finding that the polyphenolic compound tannic acid inhibits S. aureus biofilm formation in multiple biofilm models without inhibiting bacterial growth. We present evidence that tannic acid inhibits S. aureus biofilm formation via a mechanism dependent upon the putative transglycosylase IsaA. Tannic acid did not inhibit biofilm formation of an isaA mutant. Overexpression of wild-type IsaA inhibited biofilm formation, whereas overexpression of a catalytically dead IsaA had no effect. Tannin-containing drinks like tea have been found to reduce methicillin-resistant S. aureus nasal colonization. We found that black tea inhibited S. aureus biofilm development and that an isaA mutant resisted this inhibition. Antibiofilm activity was eliminated from tea when milk was added to precipitate the tannic acid. Finally, we developed a rodent model for S. aureus throat colonization and found that tea consumption reduced S. aureus throat colonization via an isaA-dependent mechanism. These findings provide insight into a molecular mechanism by which commonly consumed polyphenolic compounds, such as tannins, influence S. aureus surface colonization.

  16. Tannic Acid Inhibits Staphylococcus aureus Surface Colonization in an IsaA-Dependent Manner

    PubMed Central

    Payne, David E.; Martin, Nicholas R.; Parzych, Katherine R.; Rickard, Alex H.; Underwood, Adam

    2013-01-01

    Staphylococcus aureus is a human commensal and pathogen that is capable of forming biofilms on a variety of host tissues and implanted medical devices. Biofilm-associated infections resist antimicrobial chemotherapy and attack from the host immune system, making these infections particularly difficult to treat. In order to gain insight into environmental conditions that influence S. aureus biofilm development, we screened a library of small molecules for the ability to inhibit S. aureus biofilm formation. This led to the finding that the polyphenolic compound tannic acid inhibits S. aureus biofilm formation in multiple biofilm models without inhibiting bacterial growth. We present evidence that tannic acid inhibits S. aureus biofilm formation via a mechanism dependent upon the putative transglycosylase IsaA. Tannic acid did not inhibit biofilm formation of an isaA mutant. Overexpression of wild-type IsaA inhibited biofilm formation, whereas overexpression of a catalytically dead IsaA had no effect. Tannin-containing drinks like tea have been found to reduce methicillin-resistant S. aureus nasal colonization. We found that black tea inhibited S. aureus biofilm development and that an isaA mutant resisted this inhibition. Antibiofilm activity was eliminated from tea when milk was added to precipitate the tannic acid. Finally, we developed a rodent model for S. aureus throat colonization and found that tea consumption reduced S. aureus throat colonization via an isaA-dependent mechanism. These findings provide insight into a molecular mechanism by which commonly consumed polyphenolic compounds, such as tannins, influence S. aureus surface colonization. PMID:23208606

  17. Mass Spectrometry Analysis of Wild-Type and Knock-in Q140/Q140 Huntington's Disease Mouse Brains Reveals Changes in Glycerophospholipids Including Alterations in Phosphatidic Acid and Lyso-Phosphatidic Acid.

    PubMed

    Vodicka, Petr; Mo, Shunyan; Tousley, Adelaide; Green, Karin M; Sapp, Ellen; Iuliano, Maria; Sadri-Vakili, Ghazaleh; Shaffer, Scott A; Aronin, Neil; DiFiglia, Marian; Kegel-Gleason, Kimberly B

    2015-01-01

    Huntington's disease (HD) is a neurodegenerative disease caused by a CAG expansion in the HD gene, which encodes the protein Huntingtin. Huntingtin associates with membranes and can interact directly with glycerophospholipids in membranes. We analyzed glycerophospholipid profiles from brains of 11 month old wild-type (WT) and Q140/Q140 HD knock-in mice to assess potential changes in glycerophospholipid metabolism. Polar lipids from cerebellum, cortex, and striatum were extracted and analyzed by liquid chromatography and negative ion electrospray tandem mass spectrometry analysis (LC-MS/MS). Gene products involved in polar lipid metabolism were studied using western blotting, immuno-electron microscopy and qPCR. Significant changes in numerous species of glycerophosphate (phosphatidic acid, PA) were found in striatum, cerebellum and cortex from Q140/Q140 HD mice compared to WT mice at 11 months. Changes in specific species could also be detected for other glycerophospholipids. Increases in species of lyso-PA (LPA) were measured in striatum of Q140/Q140 HD mice compared to WT. Protein levels for c-terminal binding protein 1 (CtBP1), a regulator of PA biosynthesis, were reduced in striatal synaptosomes from HD mice compared to wild-type at 6 and 12 months. Immunoreactivity for CtBP1 was detected on membranes of synaptic vesicles in striatal axon terminals in the globus pallidus. These novel results identify a potential site of molecular pathology caused by mutant Huntingtin that may impart early changes in HD.

  18. Analysis of hydroxycinnamic acid degradation in Agrobacterium fabrum reveals a coenzyme A-dependent, beta-oxidative deacetylation pathway.

    PubMed

    Campillo, Tony; Renoud, Sébastien; Kerzaon, Isabelle; Vial, Ludovic; Baude, Jessica; Gaillard, Vincent; Bellvert, Floriant; Chamignon, Cécile; Comte, Gilles; Nesme, Xavier; Lavire, Céline; Hommais, Florence

    2014-06-01

    The soil- and rhizosphere-inhabiting bacterium Agrobacterium fabrum (genomospecies G8 of the Agrobacterium tumefaciens species complex) is known to have species-specific genes involved in ferulic acid degradation. Here, we characterized, by genetic and analytical means, intermediates of degradation as feruloyl coenzyme A (feruloyl-CoA), 4-hydroxy-3-methoxyphenyl-β-hydroxypropionyl-CoA, 4-hydroxy-3-methoxyphenyl-β-ketopropionyl-CoA, vanillic acid, and protocatechuic acid. The genes atu1416, atu1417, and atu1420 have been experimentally shown to be necessary for the degradation of ferulic acid. Moreover, the genes atu1415 and atu1421 have been experimentally demonstrated to be essential for this degradation and are proposed to encode a phenylhydroxypropionyl-CoA dehydrogenase and a 4-hydroxy-3-methoxyphenyl-β-ketopropionic acid (HMPKP)-CoA β-keto-thiolase, respectively. We thus demonstrated that the A. fabrum hydroxycinnamic degradation pathway is an original coenzyme A-dependent β-oxidative deacetylation that could also transform p-coumaric and caffeic acids. Finally, we showed that this pathway enables the metabolism of toxic compounds from plants and their use for growth, likely providing the species an ecological advantage in hydroxycinnamic-rich environments, such as plant roots or decaying plant materials.

  19. Pro-lipogenic Action of Lysophosphatidic Acid in Ovarian Cancer

    DTIC Science & Technology

    2012-07-01

    prognosis in several types of humanmalignancies, includ- ing ovarian cancer (3, 4). Furthermore, tumor cells depend heavily on or are “ addicted ” to de...Y. C., Lee, C. W., Mutoh, T., Lin, M. E., Teo, S. T., Park , K. E., Mosley, A. N., and Chun, J. (2010) LPA receptors. Subtypes and biological...Hardie, D. G. (1996) Characterization of the AMP-activated protein kinase kinase from rat liver and identification of threonine 172 as the major site at

  20. Pro-lipogenic Action of Lysophosphatidic Acid in Ovarian Cancer

    DTIC Science & Technology

    2014-04-01

    driven lipogenesis is required for proliferation of ovarian cancer cells, our results together establish a dual role for lipid metabolism ( anabolism ...proliferation of ovarian cancer cells, our results together establish a dual role for lipid metabolism ( anabolism and catabolism) in maintenance of the...Conclusion: LPA is causally linked to the aberrant lipogenesis in cancer. Significance: This study offers a new strategy to inhibit lipid anabolism in a

  1. Isolimonic acid interferes with Escherichia coli O157:H7 biofilm and TTSS in QseBC and QseA dependent fashion

    PubMed Central

    2012-01-01

    Background E. coli O157:H7 (EHEC) is an important human pathogen. The antibiotic treatment of EHEC reportedly results in release of Shiga toxin and is therefore discouraged. Consequently, alternative preventive or therapeutic strategies for EHEC are required. The objective of the current study was to investigate the effect of citrus limonoids on cell-cell signaling, biofilm formation and type III secretion system in EHEC. Results Isolimonic acid and ichangin were the most potent inhibitors of EHEC biofilm (IC25=19.7 and 28.3 μM, respectively) and adhesion to Caco-2 cells. The qPCR analysis revealed that isolimonic acid and ichangin repressed LEE encoded genes by ≈3 to 12 fold. In addition, flhDC was repressed by the two limonoids (≈3 to 7 fold). Further studies suggested that isolimonic acid interferes with AI-3/epinephrine activated cell-cell signaling pathway. Loss of biofilm inhibitory activity of isolimonic acid in ΔqseBC mutant, which could be restored upon complementation, suggested a dependence on functional QseBC. Additionally, overexpression of qseBC in wild type EHEC abated the inhibitory effect of isolimonic acid. Furthermore, the isolimonic acid failed to differentially regulate ler in ΔqseA mutant, while plasmid borne expression of qseA in ΔqseA background restored the repressive effect of isolimonic acid. Conclusions Altogether, results of study seem to suggest that isolimonic acid and ichangin are potent inhibitors of EHEC biofilm and TTSS. Furthermore, isolimonic acid appears to interfere with AI-3/epinephrine pathway in QseBC and QseA dependent fashion. PMID:23153211

  2. Oleic acid stimulates complete oxidation of fatty acids through protein kinase A-dependent activation of SIRT1-PGC1α complex.

    PubMed

    Lim, Ji-Hong; Gerhart-Hines, Zachary; Dominy, John E; Lee, Yoonjin; Kim, Sungjin; Tabata, Mitsuhisa; Xiang, Yang K; Puigserver, Pere

    2013-03-08

    Fatty acids are essential components of the dynamic lipid metabolism in cells. Fatty acids can also signal to intracellular pathways to trigger a broad range of cellular responses. Oleic acid is an abundant monounsaturated omega-9 fatty acid that impinges on different biological processes, but the mechanisms of action are not completely understood. Here, we report that oleic acid stimulates the cAMP/protein kinase A pathway and activates the SIRT1-PGC1α transcriptional complex to modulate rates of fatty acid oxidation. In skeletal muscle cells, oleic acid treatment increased intracellular levels of cyclic adenosine monophosphate (cAMP) that turned on protein kinase A activity. This resulted in SIRT1 phosphorylation at Ser-434 and elevation of its catalytic deacetylase activity. A direct SIRT1 substrate is the transcriptional coactivator peroxisome proliferator-activated receptor γ coactivator 1-α (PGC1α), which became deacetylated and hyperactive after oleic acid treatment. Importantly, oleic acid, but not other long chain fatty acids such as palmitate, increased the expression of genes linked to fatty acid oxidation pathway in a SIRT1-PGC1α-dependent mechanism. As a result, oleic acid potently accelerated rates of complete fatty acid oxidation in skeletal muscle cells. These results illustrate how a single long chain fatty acid specifically controls lipid oxidation through a signaling/transcriptional pathway. Pharmacological manipulation of this lipid signaling pathway might provide therapeutic possibilities to treat metabolic diseases associated with lipid dysregulation.

  3. Lysophosphatidate Induces Chemo-Resistance by Releasing Breast Cancer Cells from Taxol-Induced Mitotic Arrest

    PubMed Central

    Samadi, Nasser; Bekele, Raie T.; Goping, Ing Swie; Schang, Luis M.; Brindley, David N.

    2011-01-01

    Background Taxol is a microtubule stabilizing agent that arrests cells in mitosis leading to cell death. Taxol is widely used to treat breast cancer, but resistance occurs in 25–69% of patients and it is vital to understand how Taxol resistance develops to improve chemotherapy. The effects of chemotherapeutic agents are overcome by survival signals that cancer cells receive. We focused our studies on autotaxin, which is a secreted protein that increases tumor growth, aggressiveness, angiogenesis and metastasis. We discovered that autotaxin strongly antagonizes the Taxol-induced killing of breast cancer and melanoma cells by converting the abundant extra-cellular lipid, lysophosphatidylcholine, into lysophosphatidate. This lipid stimulates specific G-protein coupled receptors that activate survival signals. Methodology/Principal Findings In this study we determined the basis of these antagonistic actions of lysophosphatidate towards Taxol-induced G2/M arrest and cell death using cultured breast cancer cells. Lysophosphatidate does not antagonize Taxol action in MCF-7 cells by increasing Taxol metabolism or its expulsion through multi-drug resistance transporters. Lysophosphatidate does not lower the percentage of cells accumulating in G2/M by decreasing exit from S-phase or selective stimulation of cell death in G2/M. Instead, LPA had an unexpected and remarkable action in enabling MCF-7 and MDA-MB-468 cells, which had been arrested in G2/M by Taxol, to normalize spindle structure and divide, thus avoiding cell death. This action involves displacement of Taxol from the tubulin polymer fraction, which based on inhibitor studies, depends on activation of LPA receptors and phosphatidylinositol 3-kinase. Conclusions/Significance This work demonstrates a previously unknown consequence of lysophosphatidate action that explains why autotaxin and lysophosphatidate protect against Taxol-induced cell death and promote resistance to the action of this important therapeutic

  4. Antimicrobial medium- and long-chain free fatty acids prevent PrfA-dependent activation of virulence genes in Listeria monocytogenes.

    PubMed

    Sternkopf Lillebæk, Eva Maria; Lambert Nielsen, Stine; Scheel Thomasen, Rikke; Færgeman, Nils J; Kallipolitis, Birgitte H

    2017-03-23

    The foodborne pathogen Listeria monocytogenes is the causative agent of the invasive disease listeriosis. Infection by L. monocytogenes involves bacterial crossing of the intestinal barrier and intracellular replication in a variety of host cells. The PrfA protein is the master regulator of virulence factors required for bacterial entry, intracellular replication and cell-to-cell spread. PrfA-dependent activation of virulence genes occurs primarily in the blood and during intracellular infection. In contrast, PrfA does not play a significant role in regulation of virulence gene expression in the intestinal environment. In the gastrointestinal phase of infection, the bacterium encounters a variety of antimicrobial agents, including medium- and long-chain free fatty acids that are commonly found in our diet and as active components of bile. Here we show that subinhibitory concentrations of specific antimicrobial free fatty acids act to downregulate transcription of PrfA-activated virulence genes. Interestingly, the inhibitory effect is also evident in cells encoding a constitutively active variant of PrfA. Collectively, our data suggest that antimicrobial medium- and long-chain free fatty acids may act as signals to prevent PrfA-mediated activation of virulence genes in environments where PrfA activation is not required, such as in food and the gastrointestinal tract.

  5. Dual Action of Lysophosphatidate-Functionalised Titanium: Interactions with Human (MG63) Osteoblasts and Methicillin Resistant Staphylococcus aureus

    PubMed Central

    Skindersoe, Mette Elena; Krogfelt, Karen A.; Blom, Ashley; Jiang, Guowei; Prestwich, Glenn D.; Mansell, Jason Peter

    2015-01-01

    Titanium (Ti) is a widely used material for surgical implants; total joint replacements (TJRs), screws and plates for fixing bones and dental implants are forged from Ti. Whilst Ti integrates well into host tissue approximately 10% of TJRs will fail in the lifetime of the patient through a process known as aseptic loosening. These failures necessitate revision arthroplasties which are more complicated and costly than the initial procedure. Finding ways of enhancing early (osseo)integration of TJRs is therefore highly desirable and continues to represent a research priority in current biomaterial design. One way of realising improvements in implant quality is to coat the Ti surface with small biological agents known to support human osteoblast formation and maturation at Ti surfaces. Lysophosphatidic acid (LPA) and certain LPA analogues offer potential solutions as Ti coatings in reducing aseptic loosening. Herein we present evidence for the successful bio-functionalisation of Ti using LPA. This modified Ti surface heightened the maturation of human osteoblasts, as supported by increased expression of alkaline phosphatase. These functionalised surfaces also deterred the attachment and growth of Staphylococcus aureus, a bacterium often associated with implant failures through sepsis. Collectively we provide evidence for the fabrication of a dual-action Ti surface finish, a highly desirable feature towards the development of next-generation implantable devices. PMID:26605796

  6. Intracellular delivery of desulfated heparin with bile acid conjugation alleviates T cell-mediated inflammatory arthritis via inhibition of RhoA-dependent transcellular diapedesis.

    PubMed

    Kang, Jin Hee; Hwang, Seung Rim; Sung, Shijin; Jang, Ji Ae; Alam, Md Mahmudul; Sa, Keum Hee; Kim, Sang-Yeob; Kim, In San; Byun, Young Ro; Kang, Young Mo

    2014-06-10

    Heparin has a potential regulatory role in inflammatory diseases. However, the anticoagulant activity and poor oral bioavailability of heparin limit its use as an anti-inflammatory agent. Conjugation of bis-deoxycholic acid to 6-O-desulfated low molecular weight heparin (6DSHbD) was efficiently internalized by activated endothelial cells via a 2-step model, in which heparin attaches to adhesion molecules that facilitate accessibility of the bile acid conjugate to membrane transporters. The critical role of P-selectin during endothelial cell uptake of 6DSHbD by arthritic tissue was confirmed in p-selectin(-/-) arthritic mice. Intracellular 6DSHbD inhibited transcellular diapedesis of T cells through activated endothelial cells and impaired both the formation of ICAM-1-rich docking structures at the T cell contact surface and subsequent cytoskeletal rearrangement. Furthermore, 6DSHbD blocked activation of RhoA-GTPase and phosphorylation of ezrin/radixin/moesin induced by ICAM-1 cross-linking on activated endothelial cells, thereby impairing lymphocyte transcellular transmigration. After oral administration 6DSHbD was preferentially delivered to inflamed joint tissue, particularly in and around post-capillary venular endothelium and inhibited effector T cell homing to arthritic joints. Aggravation of collagen-induced arthritis conferred by the transfer of effector T cells was suppressed by oral 6DSHbD. Thus, intracellular heparin exerts anti-inflammatory effects through the inhibition of RhoA-dependent transendothelial recruitment of T cells and may have applications in the treatment of chronic inflammatory arthritis.

  7. Gintonin, newly identified compounds from ginseng, is novel lysophosphatidic acids-protein complexes and activates G protein-coupled lysophosphatidic acid receptors with high affinity.

    PubMed

    Hwang, Sung Hee; Shin, Tae-Joon; Choi, Sun-Hye; Cho, Hee-Jung; Lee, Byung-Hwan; Pyo, Mi Kyung; Lee, Jun-Ho; Kang, Jiyeon; Kim, Hyeon-Joong; Park, Chan-Woo; Shin, Ho-Chul; Nah, Seung-Yeol

    2012-02-01

    Recently, we isolated a subset of glycolipoproteins from Panax ginseng, that we designated gintonin, and demonstrated that it induced [Ca2+]i transients in cells via G protein-coupled receptor (GPCR) signaling pathway(s). However, active components responsible for Ca2+ mobilization and the corresponding receptor(s) were unknown. Active component(s) for [Ca2+]i transients of gintonin were analyzed by liquid chromatography-electrospray ionization-tandem mass spectrometry and ion-mobility mass spectrometry, respectively. The corresponding receptor(s)were investigated through gene expression assays. We found that gintonin contains LPA C18:2 and other LPAs. Proteomic analysis showed that ginseng major latex-like protein and ribonuclease-like storage proteins are protein components of gintonin. Gintonin induced [Ca2+]i transients in B103 rat neuroblastoma cells transfected with human LPA receptors with high affinity in order of LPA2 >LPA5 > LPA1 > LPA3 > LPA4. The LPA1/LPA3 receptor antagonist Ki16425 blocked gintonin action in cells expressing LPA1 or LPA3. Mutations of binding sites in the LPA3 receptor attenuated gintonin action. Gintonin acted via pertussis toxin (PTX)-sensitive and -insensitive G protein-phospholipase C (PLC)-inositol 1,4,5-trisphosphate (IP3)-Ca2+ pathways. However, gintonin had no effects on other receptors examined. In human umbilical vein endothelial cells (HUVECs) gintonin stimulated cell proliferation and migration. Gintonin stimulated ERK1/2 phosphorylation. PTX blocked gintonin-mediated migration and ERK1/2 phosphorylation. In PC12 cells gintonin induced morphological changes, which were blocked by Rho kinase inhibitorY-27632. Gintonin contains GPCR ligand LPAs in complexes with ginseng proteins and could be useful in the development of drugs targeting LPA receptors.

  8. An ultra-high performance liquid chromatography-tandem mass spectrometric assay for quantifying 3-ketocholanoic acid: Application to the human liver microsomal CYP3A-dependent lithocholic acid 3-oxidation assay.

    PubMed

    Bansal, Sumit; Chai, Swee Fen; Lau, Aik Jiang

    2016-06-15

    Lithocholic acid (LCA), a hepatotoxic and carcinogenic bile acid, is metabolized to 3-ketocholanoic acid (3-KCA) by cytochrome P450 3A (CYP3A). In the present study, the objectives were to develop and validate an ultra-high performance liquid chromatography-tandem mass spectrometric (UPLC-MS/MS) method to quantify 3-KCA and apply it to the human liver microsomal CYP3A-dependent LCA 3-oxidation assay. Chromatographic separation was achieved on a Waters ACQUITY™ UPLC C18 column (50×2.1mm, 1.7μm) with a gradient system consisting of 0.1% v/v formic acid in water (solvent A) and 0.1% v/v formic acid in acetonitrile (solvent B). The retention time was 3.73min for 3-KCA and 2.73min for cortisol (internal standard). Positive electrospray ionization with multiple reaction monitoring (MRM) mode was used to quantify 3-KCA (m/z 375.4→135.2) and cortisol (m/z 363.5→121.0). The limit of detection of 3-KCA was 10μM, the lower limit of quantification was 33.3μM, and the calibration curve was linear from 0.05-10μM with r(2)>0.99. Intra-day and inter-day accuracy and precision were <13.7%. The quality control samples were stable when assessed after 4h at room temperature, 24h at 4°C, 14days at -20°C, and three freeze-thaw cycles. The liver microsomal matrix did not affect 3-KCA quantification. The amount of KCA formed in the human liver microsomal LCA 3-oxidation assay was linear with respect to the amount of microsomal protein (up to 40μg) and incubation time (5-30min). Enzyme kinetics experiment indicated that LCA 3-oxidation followed the Michaelis-Menten model with an apparent Km of 26±7μM and Vmax of 303±50pmol/min/mg protein. This novel UPLC-MS/MS method for quantifying 3-KCA offers a specific, sensitive, and fast approach to determine liver microsomal LCA 3-oxidation. Copyright © 2016 Elsevier B.V. All rights reserved.

  9. Recent advances in targeting the autotaxin-lysophosphatidate-lipid phosphate phosphatase axis in vivo

    PubMed Central

    Benesch, Matthew G.K.; Tang, Xiaoyun; Venkatraman, Ganesh; Bekele, Raie T.; Brindley, David N.

    2016-01-01

    Abstract Extracellular lysophosphatidate (LPA) is a potent bioactive lipid that signals through six G-protein-coupled receptors. This signaling is required for embryogenesis, tissue repair and remodeling processes. LPA is produced from circulating lysophosphatidylcholine by autotaxin (ATX), and is degraded outside cells by a family of three enzymes called the lipid phosphate phosphatases (LPPs). In many pathological conditions, particularly in cancers, LPA concentrations are increased due to high ATX expression and low LPP activity. In cancers, LPA signaling drives tumor growth, angiogenesis, metastasis, resistance to chemotherapy and decreased efficacy of radiotherapy. Hence, targeting the ATX-LPA-LPP axis is an attractive strategy for introducing novel adjuvant therapeutic options. In this review, we will summarize current progress in targeting the ATX-LPA-LPP axis with inhibitors of autotaxin activity, LPA receptor antagonists, LPA monoclonal antibodies, and increasing low LPP expression. Some of these agents are already in clinical trials and have applications beyond cancer, including chronic inflammatory diseases. PMID:27533936

  10. Derivatives of Dictyostelium differentiation-inducing factors inhibit lysophosphatidic acid–stimulated migration of murine osteosarcoma LM8 cells

    SciTech Connect

    Kubohara, Yuzuru; Komachi, Mayumi; Homma, Yoshimi; Kikuchi, Haruhisa; Oshima, Yoshiteru

    2015-08-07

    Osteosarcoma is a common metastatic bone cancer that predominantly develops in children and adolescents. Metastatic osteosarcoma remains associated with a poor prognosis; therefore, more effective anti-metastatic drugs are needed. Differentiation-inducing factor-1 (DIF-1), −2, and −3 are novel lead anti-tumor agents that were originally isolated from the cellular slime mold Dictyostelium discoideum. Here we investigated the effects of a panel of DIF derivatives on lysophosphatidic acid (LPA)-induced migration of mouse osteosarcoma LM8 cells by using a Boyden chamber assay. Some DIF derivatives such as Br-DIF-1, DIF-3(+2), and Bu-DIF-3 (5–20 μM) dose-dependently suppressed LPA-induced cell migration with associated IC{sub 50} values of 5.5, 4.6, and 4.2 μM, respectively. On the other hand, the IC{sub 50} values of Br-DIF-1, DIF-3(+2), and Bu-DIF-3 versus cell proliferation were 18.5, 7.2, and 2.0 μM, respectively, in LM8 cells, and >20, 14.8, and 4.3 μM, respectively, in mouse 3T3-L1 fibroblasts (non-transformed). Together, our results demonstrate that Br-DIF-1 in particular may be a valuable tool for the analysis of cancer cell migration, and that DIF derivatives such as DIF-3(+2) and Bu-DIF-3 are promising lead anti-tumor agents for the development of therapies that suppress osteosarcoma cell proliferation, migration, and metastasis. - Highlights: • LPA induces cell migration (invasion) in murine osteosarcoma LM8 cells. • DIFs are novel lead anti-tumor agents found in Dictyostelium discoideum. • We examined the effects of DIF derivatives on LPA-induced LM8 cell migration in vitro. • Some of the DIF derivatives inhibited LPA-induced LM8 cell migration.

  11. Aberrant amino acid signaling promotes growth and metastasis of hepatocellular carcinomas through Rab1A-dependent activation of mTORC1 by Rab1A

    PubMed Central

    Yang, Yang; Zhang, Mei-Yin; Rao, Hui-Lan; Wang, Hui-Yun; Zheng, X.F. Steven

    2015-01-01

    mTORC1 is a master regulator of cell growth and proliferation, and an established anticancer drug target. Aberrant mTORC1 signaling is common in hepatocellular carcinoma (HCC), but the underlying mechanism remains elusive. Rab1A is a newly identified mTORC1 activator that mediates an alternative amino acid (AA) signaling branch to Rag GTPases. Because liver is a physiological hub for nutrient sensing and metabolic homeostasis, we investigated the possible role of Rab1A in HCC. We found that Rab1A is frequently overexpressed in HCC, which enhances hyperactive AA-mTORC1 signaling, promoting malignant growth and metastasis of HCC in vitro and in vivo. Moreover, aberrant Rab1A expression is closely associated with poor prognosis. Strikingly, aberrant Rab1A overexpression leads to increased rapamycin sensitivity, indicating that inappropriate activation of AA signaling is a cancer-driving event in HCC. Our findings further suggest that Rab1A is a valuable biomarker for prognosis and personalized mTORC1-targeted therapy in liver cancer. PMID:26308575

  12. DNA adducts formed from the probable proximate carcinogen, N-hydroxy-3,2' -dimethyl-4-aminobiphenyl, by acid catalysis or S-acetyl coenzyme A-dependent enzymatic esterification.

    PubMed

    Flammang, T J; Westra, J G; Kadlubar, F F; Beland, F A

    1985-02-01

    The arylamine carcinogen 3,2'-dimethyl-4-aminobiphenyl (DMABP) has been proposed to be metabolically activated to DNA-binding derivatives through the formation of an N-hydroxy intermediate. In this study, the subsequent activation of N-hydroxy-DMABP through acid catalysis or enzymatic esterification was examined. [Ring-3H]N-hydroxy-DMABP was reacted with calf thymus DNA at pH 4.6 for 15 min to yield 370 arylamine residues per 10(6) nucleotides, while at pH 7.4 the binding was only two residues per 10(6) nucleotides. The DNA modified under acidic conditions was enzymatically hydrolyzed and analyzed by h.p.l.c. which indicated the presence of three major adducts. The products were identified by spectral and chemical properties as N-(deoxyguanosin-8-yl)-DMABP (60-70%), 5-(deoxyguanosin-N2-yl)-DMABP (2-3%) and N-(deoxyadenosin-8-yl)-DMABP (1-3%). The same adducts have previously been detected in the liver and colon of rats administered DMABP or its hydroxamic acid. Incubation of rat hepatic or intestinal cytosol at pH 7.4 for 15 min with [ring-3H]N-hydroxy-DMABP in the presence of S-acetyl coenzyme A (AcCoA) and calf thymus DNA resulted in DNA binding at levels of 30-80 arylamine residues per 10(6) nucleotides. H.p.l.c. analysis of the DNA modified in the presence of AcCoA indicated the formation of the same adducts detected in the acid-catalyzed reactions. When arylhydroxamic acid N,O-acyltransferase assays were conducted with rat liver cytosol and N-acetyl-N-hydroxy-DMABP as the substrate, binding to nucleic acids was not observed. Similarly, 3'-phosphoadenosine-5'-phosphosulfate-dependent sulfotransferase-mediated DNA binding could not be demonstrated. These data indicate that in a suitable acidic environment, N-hydroxy-DMABP will react with DNA to yield the same adducts found in vivo. Under neutral conditions, however, N-hydroxy-DMABP appears to undergo AcCoA-dependent transacetylation to an electrophilic acetoxy ester which will spontaneously react with DNA.

  13. Phosphatidic acid signaling mediates lung cytokine expression and lung inflammatory injury after hemorrhage in mice.

    PubMed

    Abraham, E; Bursten, S; Shenkar, R; Allbee, J; Tuder, R; Woodson, P; Guidot, D M; Rice, G; Singer, J W; Repine, J E

    1995-02-01

    Because phosphatidic acid (PA) pathway signaling may mediate many basic reactions involving cytokine-dependent responses, we investigated the effects of CT1501R, a functional inhibitor of the enzyme lysophosphatidic acid acyltransferase (LPAAT) which converts lysophosphatidic acid (Lyso-PA) to PA. We found that CT1501R treatment not only prevented hypoxia-induced PA increases and lyso-PA consumption in human neutrophils, but also prevented neutrophil chemotaxis and adherence in vitro, and lung injury and lung neutrophil accumulation in mice subjected to hemorrhage and resuscitation. In addition, CT1501R treatment prevented increases in mRNA levels and protein production of a variety of proinflammatory cytokines in multiple lung cell populations after blood loss and resuscitation. Our results indicate the fundamental role of PA metabolism in the development of acute inflammatory lung injury after blood loss.

  14. Phosphatidic acid metabolism in rat liver cell nuclei.

    PubMed

    Gaveglio, Virginia L; Pasquaré, Susana J; Giusto, Norma M

    2013-04-02

    The aim of the present research was to analyze the pathways for phosphatidic acid metabolism in purified nuclei from liver. Lipid phosphate phosphatase, diacylglycerol lipase, monoacylglycerol lipase and PA-phospholipase type A activities were detected. The presence of lysophosphatidic acid significantly reduced DAG production while sphingosine 1-phoshate and ceramide 1-phosphate reduced MAG formation from PA. Using different enzymatic modulators (detergents and ions) an increase in the PA metabolism by phospholipase type A was observed. Our findings evidence an active PA metabolism in purified liver nuclei which generates important lipid second messengers, and which could thus be involved in nuclear processes such as gene transcription.

  15. Cyclic phosphatidic acid - a unique bioactive phospholipid.

    PubMed

    Fujiwara, Yuko

    2008-09-01

    Cyclic phosphatidic acid (CPA) is a naturally occurring analog of the growth factor-like phospholipid mediator, lysophosphatidic acid (LPA). The sn-2 hydroxy group of CPA forms a 5-membered ring with the sn-3 phosphate. CPA affects numerous cellular functions, including anti-mitogenic regulation of the cell cycle, induction of stress fiber formation, inhibition of tumor cell invasion and metastasis, and regulation of differentiation and survival of neuronal cells. Interestingly, many of these cellular responses caused by CPA oppose those of LPA despite the activation of apparently overlapping receptor populations. Since the early 1990s, studies on CPA actions gradually developed, and we are now beginning to understand the importance of this lipid. In this review, we focus on the current knowledge about CPA, including enzymatic formation of CPA, unique biological activities and biological targets of CPA, and we also explore metabolically stabilized CPA analogs.

  16. Cyclic Phosphatidic Acid – A Unique Bioactive Phospholipid

    PubMed Central

    Fujiwara, Yuko

    2008-01-01

    Cyclic phosphatidic acid (CPA) is a naturally occurring analog of the growth factor-like phospholipid mediator, lysophosphatidic acid (LPA). The sn-2 hydroxy group of CPA forms a 5-membered ring with the sn-3 phosphate. CPA affects numerous cellular functions, including antimitogenic regulation of the cell cycle, induction of stress fiber formation, inhibition of tumor cell invasion and metastasis, and regulation of differentiation and survival of neuronal cells. Interestingly, many of these cellular responses caused by CPA oppose those of LPA despite the activation of apparently overlapping receptor populations. Since the early 1990s, studies on CPA actions gradually developed, and we are now beginning to understand the importance of this lipid. In this review, we focus on the current knowledge about CPA, including enzymatic formation of CPA, unique biological activities and biological targets of CPA, and we also explore metabolically stabilized CPA analogs. PMID:18554524

  17. Structure of Acid phosphatases.

    PubMed

    Araujo, César L; Vihko, Pirkko T

    2013-01-01

    difference that can be exploited in in vitro assays to differentiate between different kinds of phosphatase activity. The search for more sensitive and specific methods of detection in clinical laboratory applications led to the development of radioimmunoassays (RIA) for determination of prostatic acid phosphatase in serum. These methods permit the direct quantification of the enzyme regardless of its activity status. Therefore, an independent structural classification exists that helps to group these enzymes according to their structural features and mechanisms. Based on this we can distinguish the histidine acid phosphatases (Van Etten, Ann N Y Acad Sci 390:27-51, 1982), the low molecular weight protein tyrosine acid phosphatases and the metal-ion dependent phosphatases. A note of caution is worthwhile mentioning here. The nomenclature of acid phosphatases has not been particularly easy for those new to the subject. Unfortunately, the acronym PAP is very common in the literature about purple acid phosphatases and prostatic acid phosphatase. In addition, LPAP is the acronym chosen to refer to the lysophosphatidic acid phosphatase which is a different enzyme. It is important to bear in mind this distinction while reviewing the literature to avoid confusion.

  18. DNA microarray analysis reveals a role for lysophosphatidic acid in the regulation of anti-inflammatory genes in MC3T3-E1 cells

    SciTech Connect

    Waters, Katrina M.; Tan, Ruimin; Genetos, Damian C.; Verma, Seema; Yellowley, Clare E.; Karin, Norm J.

    2007-11-01

    DNA microarray analysis revealed that treatment of bone cells with a lipid growth factor led to extensive changes in gene expression. Particular relevance to fracture healing and inflammation was revealed.

  19. Lysophosphatidic Acid and Apolipoprotein A1 Predict Increased Risk of Developing World Trade Center Lung Injury: A Nested Case-Control Study

    PubMed Central

    Tsukiji, Jun; Cho, Soo Jung; Echevarria, Ghislaine C.; Kwon, Sophia; Joseph, Phillip; Schenck, Edward J.; Naveed, Bushra; Prezant, David J.; Rom, William N.; Schmidt, Ann Marie; Weiden, Michael D.; Nolan, Anna

    2014-01-01

    Rationale Metabolic syndrome, inflammatory and vascular injury markers measured in serum after WTC exposures predict abnormal FEV1. We hypothesized that elevated LPA levels predict FEV1

  20. Botulinum Toxin Type A Targets RhoB to Inhibit Lysophosphatidic Acid-Stimulated Actin Reorganization and Acetylcholine Release in NGF-Treated Differentiated PC12 Cells

    DTIC Science & Technology

    2003-07-01

    from Sternberger Monoclonals (Lutherville, MD). Botulinum toxin type A (BoNT/A) was procured from Wako (Richmond, VA). 1 Report Documentation...Page Form ApprovedOMB No. 0704-0188 Public reporting burden for the collection of information is estimated to average 1 hour per response, including the...failing to comply with a collection of information if it does not display a currently valid OMB control number. 1 . REPORT DATE 01 JUL 2003 2. REPORT TYPE

  1. Seipin deficiency alters fatty acid Delta9 desaturation and lipid droplet formation in Berardinelli-Seip congenital lipodystrophy.

    PubMed

    Boutet, Emilie; El Mourabit, Haquima; Prot, Matthieu; Nemani, Mona; Khallouf, Eliane; Colard, Odile; Maurice, Michèle; Durand-Schneider, Anne-Marie; Chrétien, Yves; Grès, Sandra; Wolf, Claude; Saulnier-Blache, Jean-Sébastien; Capeau, Jacqueline; Magré, Jocelyne

    2009-06-01

    Berardinelli-Seip congenital lipodystrophy (BSCL) is a rare recessive disease characterized by near absence of adipose tissue and severe insulin resistance. In most cases, BSCL is due to loss-of-function mutations in the genes encoding either seipin of unknown function or 1-acyl-glycerol-3-phosphate O-acyltransferase 2 (AGPAT2) which catalyses the formation of phosphatidic acid from lysophosphatidic acid. We studied the lipid profile of lymphoblastoid cell-lines from 20 BSCL patients with null mutations in the genes encoding either seipin (n=12) or AGPAT2 (n=8) in comparison to nine control cell-lines. In seipin deficient cells, we observed alterations in the pattern of lipid droplets which were decreased in size and increased in number as compared to control cells. We also observed alterations in the triglycerides content as well as in the fatty acid composition from triglycerides and phosphatidylethanolamine, with an increased proportion of saturated fatty acids at the expense of the corresponding monounsaturated fatty acids, reflecting a defect in Delta9-desaturase activity. In AGPAT2 deficient cells, no specific alterations in lipid droplet pattern nor in fatty acid composition was observed but the cellular level of lysophosphatidic acid was increased as compared to that of control and seipin deficient cells. These results indicate that seipin like AGPAT2 is involved in lipid metabolism but exerts a different function. Seipin intervenes at a proximal step in triglycerides and phospholipids biosynthesis being involved in the pathway that links fatty acid Delta9 desaturation to lipid droplet formation. These findings provide new insights into how seipin deficiency causes severe lipodystrophy.

  2. Activation of cyclin A-dependent protein kinases during apoptosis.

    PubMed Central

    Meikrantz, W; Gisselbrecht, S; Tam, S W; Schlegel, R

    1994-01-01

    Apoptosis was induced in S-phase-arrested HeLa cells by staurosporine, caffeine, 6-dimethylaminopurine, and okadaic acid, agents that activate M-phase-promoting factor and induce premature mitosis in similarly treated hamster cell lines. Addition of these agents to asynchronously growing HeLa cells or to cells arrested in early G1 phase with lovastatin had little or no effect. S-phase arrest also promoted tumor necrosis factor alpha-induced apoptosis, eliminating the normal requirement for simultaneous cycloheximide treatment. For all of the apoptosis-inducing agents tested, the appearance of condensed chromatin was accompanied by 2- to 7-fold increases in cyclin A-associated histone H1 kinase activity, levels approximating the mitotic value. Where examined, both Cdc2 and Cdk2, the catalytic subunits known to associate with cyclin A, were activated. Stable overexpression of bcl-2 suppressed the apoptosis-inducing activity of all agents tested and reduced the amount of Cdc2 and Cdk2 in the nucleus, suggesting a possible mechanism by which bcl-2 inhibits the chromatin condensation characteristic of apoptosis. These findings suggest that at least one of the biochemical steps required for mitosis, activation of cyclin A-dependent protein kinases, is also an important event during apoptosis. Images PMID:8170983

  3. Comparison of oleic acid metabolism in the soybean (Glycine max (L. ) Merr. ) genotypes Williams and A5, a mutant with decreased linoleic acid in the seed

    SciTech Connect

    Martin, B.A.; Rinne, R.W.

    1986-05-01

    The metabolism of oleoyl coenzyme A (CoA) was examined in developing seed from two soybean (Glycine max (L.) Merr.) genotypes: Williams, a standard cultivar and A5, a mutant containing nearly twice the oleic acid (18:1) content of Williams. The in vitro rates of esterification of oleoyl-CoA to lysophosphatides by acyl-CoA: lysophosphatidylcholine acyltransferase was similar in both genotypes and lysophosphatidyl-ethanolamine was a poor substrate. Crude extracts desaturated exogenous (1-/sup 14/C)dioleoyl phosphatidylcholine at 14% of the rate achieved with (1-/sup 14/C)oleoyl-CoA, and 50 micromolar lysophosphaatidylcholine. The desaturase enzyme also required NADH for full activity. Extracts from Williams contained 1.5-fold more oleoyl phosphatidylcholine desaturase activity, on a fresh weight basis, than did A5 and appeared to have a similar affinity for oleoyl-CoA. There was 1.2- to 1.9-fold more linoleic acid (18:2) in phosphatidylcholine from Williams than from A5, measured at two stages of development, but both genotypes had a similar distribution of fatty acids in the one and two positions. Phosphatidylethanolamine in A5 contained relatively more linoleic acid (18:2) in the one position than did Williams. The increased oleic acid (18:1) content in A5 appeared to be a result of decreased rates of 18:1 desaturation of oleoyl-phosphatidylcholine in this genotype.

  4. Acetal phosphatidic acids: novel platelet aggregating agents.

    PubMed

    Brammer, J P; Maguire, M H; Walaszek, E J; Wiley, R A

    1983-05-01

    1 Palmitaldehyde, olealdehyde and linolealdehyde acetal phosphatidic acids induced rapid shape change and dose-dependent biphasic aggregation of human platelets in platelet-rich plasma; aggregation was reversible at low doses and irreversible at high doses of the acetal phosphatidic acids. The palmitaldehyde congener elicited monophasic dose-dependent aggregation of sheep platelets in platelet-rich plasma.2 The threshold concentration for palmitaldehyde acetal phosphatidic acid (PGAP)-induced platelet aggregation was 2.5-5 muM for human platelets and 0.25-0.5 muM for sheep platelets. PGAP was 4-5 times as potent versus human platelets as the olealdehyde and linolealdehyde acetal phosphatidic acids, which were equipotent.3 PGAP-induced irreversible aggregation of [(14)C]-5-hydroxytryptamine ([(14)C]-5-HT)-labelled human platelets in platelet-rich plasma was accompanied by release of 44.0+/-2.4% (s.e.) of the platelet [(14)C]-5-HT; reversible aggregation was not associated with release. In contrast, PGAP-induced release of [(14)C]-5-HT-labelled sheep platelets was dose-dependent.4 The adenosine diphosphate (ADP) antagonist, 2-methylthio-AMP, and the cyclo-oxygenase inhibitor, aspirin, abolished PGAP-induced second phase aggregation and release in human platelets but did not affect the first, reversible, phase of aggregation. Both the first and second phases of PGAP-induced aggregation were abolished by chlorpromazine, by the phospholipase A(2) inhibitor, mepacrine, and by nmolar concentrations of prostaglandin E(1) (PGE(1)); these agents abolished the second, but not the first phase of ADP-induced aggregation.5 The related phospholipids, lecithin, lysolecithin and phosphatidic acid, at <100 muM, neither induced aggregation of human platelets in platelet-rich plasma, nor modified PGAP-induced aggregation; 1-palmityl lysophosphatidic acid elicited aggregation of human platelets at a threshold concentration of 100 muM.6 It is concluded that the acetal phosphatidic acids

  5. The multigene family of lysophosphatidate acyltransferase (LPAT)-related enzymes in Ricinus communis: cloning and molecular characterization of two LPAT genes that are expressed in castor seeds.

    PubMed

    Arroyo-Caro, José María; Chileh, Tarik; Kazachkov, Michael; Zou, Jitao; Alonso, Diego López; García-Maroto, Federico

    2013-02-01

    The multigene family encoding proteins related to lysophosphatidyl-acyltransferases (LPATs) has been analyzed in the castor plant Ricinus communis. Among them, two genes designated RcLPAT2 and RcLPATB, encoding proteins with LPAT activity and expressed in the developing seed, have been cloned and characterized in some detail. RcLPAT2 groups with well characterized members of the so-called A-class LPATs and it shows a generalized expression pattern in the plant and along seed development. Enzymatic assays of RcLPAT2 indicate a preference for ricinoleoyl-CoA over other fatty acid thioesters when ricinoleoyl-LPA is used as the acyl acceptor, while oleoyl-CoA is the preferred substrate when oleoyl-LPA is employed. RcLPATB groups with B-class LPAT enzymes described as seed specific and selective for unusual fatty acids. However, RcLPATB exhibit a broad specificity on the acyl-CoAs, with saturated fatty acids (12:0-16:0) being the preferred substrates. RcLPATB is upregulated coinciding with seed triacylglycerol accumulation, but its expression is not restricted to the seed. These results are discussed in the light of a possible role for LPAT isoenzymes in the channelling of ricinoleic acid into castor bean triacylglycerol. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

  6. Increasing erucic acid content through combination of endogenous low polyunsaturated fatty acids alleles with Ld-LPAAT + Bn-fae1 transgenes in rapeseed (Brassica napus L.).

    PubMed

    Nath, Ujjal K; Wilmer, Jeroen A; Wallington, Emma J; Becker, Heiko C; Möllers, Christian

    2009-02-01

    High erucic acid rapeseed (HEAR) oil is of interest for industrial purposes because erucic acid (22:1) and its derivatives are important renewable raw materials for the oleochemical industry. Currently available cultivars contain only about 50% erucic acid in the seed oil. A substantial increase in erucic acid content would significantly reduce processing costs and could increase market prospects of HEAR oil. It has been proposed that erucic acid content in rapeseed is limited because of insufficient fatty acid elongation, lack of insertion of erucic acid into the central sn-2 position of the triaclyglycerol backbone and due to competitive desaturation of the precursor oleic acid (18:1) to linoleic acid (18:2). The objective of the present study was to increase erucic content of HEAR winter rapeseed through over expression of the rapeseed fatty acid elongase gene (fae1) in combination with expression of the lysophosphatidic acid acyltransferase gene from Limnanthes douglasii (Ld-LPAAT), which enables insertion of erucic acid into the sn-2 glycerol position. Furthermore, mutant alleles for low contents of polyunsaturated fatty acids (18:2 + 18:3) were combined with the transgenic material. Selected transgenic lines showed up to 63% erucic acid in the seed oil in comparison to a mean of 54% erucic acid of segregating non-transgenic HEAR plants. Amongst 220 F(2) plants derived from the cross between a transgenic HEAR line and a non-transgenic HEAR line with a low content of polyunsaturated fatty acids, recombinant F(2) plants were identified with an erucic acid content of up to 72% and a polyunsaturated fatty acid content as low as 6%. Regression analysis revealed that a reduction of 10% in polyunsaturated fatty acids content led to a 6.5% increase in erucic acid content. Results from selected F(2) plants were confirmed in the next generation by analysing F(4) seeds harvested from five F(3) plants per selected F(2) plant. F(3) lines contained up to 72% erucic acid and

  7. Free fatty acid receptor (FFAR) agonists inhibit proliferation of human ovarian cancer cells.

    PubMed

    Hopkins, Mandi M; Meier, Kathryn E

    2017-07-01

    Many cellular actions of omega-3 fatty acids are mediated by two G protein-coupled receptors, FFA1 and FFA4, free fatty acid receptor (FFAR) family members that are activated by these dietary constituents. FFAR agonists inhibit proliferation of human prostate and breast cancer cells. Since omega-3 fatty acids can inhibit ovarian cancer cell growth, the current study tested the potential role of FFARs in the response. OVCAR3 and SKOV3 human ovarian cancer cell lines express mRNA for FFA1; FFA4 mRNA was detected at low levels in SKOV3 but not OVCAR3. Lysophosphatidic acid (LPA) and epidermal growth factor (EGF) stimulated proliferation of both cell lines; these responses were inhibited by eicosopentaneoic acid (EPA) and by GW9508, a synthetic FFAR agonist. The LPA antagonist Ki16425 also inhibited LPA- and EGF-induced proliferation; FFAR agonists had no further effect when added with Ki16425. The results suggest that FFARs are potential targets for ovarian cancer therapy. Copyright © 2017. Published by Elsevier Ltd.

  8. Polyamines are essential for the synthesis of 2-ricinoleoyl phosphatidic acid in developing seeds of castor.

    PubMed

    Tomosugi, Mitsuhiro; Ichihara, Ken'ichi; Saito, Kazumi

    2006-01-01

    The major fatty acid component of castor (Ricinus communis L.) oil is ricinoleic acid (12-hydroxy-cis-9-octadecenoic acid), and unsaturated hydroxy acid accounts for >85% of the total fatty acids in triacylglycerol (TAG). TAG had a higher ricinoleate content at position 2 than at positions 1 and 3. Although lysophosphatidic acid (LPA) acyltransferase (EC 2.3.1.51), which catalyzes acylation of LPA at position 2, was expected to utilize ricinoleoyl-CoA preferentially over other fatty acyl-CoAs, no activity was found for ricinoleoyl-CoA in vitro at concentrations at which other unsaturated acyl-CoAs were incorporated rapidly. However, activity for ricinoleoyl-CoA appeared with addition of polyamines (putrescine, spermidine, and spermine), while polyamines decreased the rates of incorporation of other acyl-CoAs into position 2. The order of effect of polyamines on LPA acyltransferase activity was spermine > spermidine > putrescine. At concentrations of spermine and spermidine of >0.1 mM, ricinoleoyl-CoA served as an effective substrate for LPA acyltransferase reaction. The concentrations of spermine and spermidine in the developing seeds were estimated at approximately 0.09 and approximately 0.63 mM, respectively. These stimulatory effects for incorporation of ricinoleate were specific to polyamines, but basic amino acids were ineffective as cations. In contrast, in microsomes from safflower seeds that do not contain ricinoleic acid, spermine and spermidine stimulated the LPA acyltransferase reaction for all acyl-CoAs tested, including ricinoleoyl-CoA. Although the fatty acid composition of TAG depends on both acyl-CoA composition in the cell and substrate specificity of acyltransferases, castor bean polyamines are crucial for incorporation of ricinoleate into position 2 of LPA. Polyamines are essential for synthesis of 2-ricinoleoyl phosphatidic acid in developing castor seeds.

  9. Expression of Castor LPAT2 Enhances Ricinoleic Acid Content at the sn-2 Position of Triacylglycerols in Lesquerella Seed

    PubMed Central

    Chen, Grace Q.; van Erp, Harrie; Martin-Moreno, Jose; Johnson, Kumiko; Morales, Eva; Browse, John; Eastmond, Peter J.; Lin, Jiann-Tsyh

    2016-01-01

    Lesquerella is a potential industrial oilseed crop that makes hydroxy fatty acid (HFA). Unlike castor its seeds are not poisonous but accumulate lesquerolic acid mostly at the sn-1 and sn-3 positions of triacylglycerol (TAG), whereas castor contains ricinoleic acid (18:1OH) at all three positions. To investigate whether lesquerella can be engineered to accumulate HFAs in the sn-2 position, multiple transgenic lines were made that express castor lysophosphatidic acid acyltransferase 2 (RcLPAT2) in the seed. RcLPAT2 increased 18:1OH at the sn-2 position of TAGs from 2% to 14%–17%, which resulted in an increase of tri-HFA-TAGs from 5% to 13%–14%. Our result is the first example of using a LPAT to increase ricinoleic acid at the sn-2 position of seed TAG. This work provides insights to the mechanism of HFA-containing TAG assembly in lesquerella and directs future research to optimize this plant for HFA production. PMID:27058535

  10. Metabolic engineering of medium-chain fatty acid biosynthesis in Nicotiana benthamiana plant leaf lipids

    PubMed Central

    Reynolds, Kyle B.; Taylor, Matthew C.; Zhou, Xue-Rong; Vanhercke, Thomas; Wood, Craig C.; Blanchard, Christopher L.; Singh, Surinder P.; Petrie, James R.

    2015-01-01

    Various research groups are investigating the production of oil in non-seed biomass such as leaves. Recently, high levels of oil accumulation have been achieved in plant biomass using a combination of biotechnological approaches which also resulted in significant changes to the fatty acid composition of the leaf oil. In this study, we were interested to determine whether medium-chain fatty acids (MCFA) could be accumulated in leaf oil. MCFA are an ideal feedstock for biodiesel and a range of oleochemical products including lubricants, coatings, and detergents. In this study, we explore the synthesis, accumulation, and glycerolipid head-group distribution of MCFA in leaves of Nicotiana benthamiana after transient transgenic expression of C12:0-, C14:0-, and C16:0-ACP thioesterase genes. We demonstrate that the production of these MCFA in leaf is increased by the co-expression of the WRINKLED1 (WRI1) transcription factor, with the lysophosphatidic acid acyltransferase (LPAAT) from Cocos nucifera being required for the assembly of tri-MCFA TAG species. We also demonstrate that the newly-produced MCFA are incorporated into the triacylglycerol of leaves in which WRI1 + diacylglycerol acyltransferase1 (DGAT1) genes are co-expressed for increased oil accumulation. PMID:25852716

  11. Dilinoleoyl-phosphatidic acid mediates reduced IRS-1 tyrosine phosphorylation in rat skeletal muscle cells and mouse muscle.

    PubMed

    Cazzolli, R; Mitchell, T W; Burchfield, J G; Pedersen, D J; Turner, N; Biden, T J; Schmitz-Peiffer, C

    2007-08-01

    Insulin resistance in skeletal muscle is strongly associated with lipid oversupply, but the intracellular metabolites and underlying mechanisms are unclear. We therefore sought to identify the lipid intermediates through which the common unsaturated fatty acid linoleate causes defects in IRS-1 signalling in L6 myotubes and mouse skeletal muscle. Cells were pre-treated with 1 mmol/l linoleate for 24 h. Subsequent insulin-stimulated IRS-1 tyrosine phosphorylation and its association with the p85 subunit of phosphatidylinositol 3-kinase were determined by immunoblotting. Intracellular lipid species and protein kinase C activation were modulated by overexpression of diacylglycerol kinase epsilon, which preferentially converts unsaturated diacylglycerol into phosphatidic acid, or by inhibition of lysophosphatidic acid acyl transferase with lisofylline, which reduces phosphatidic acid synthesis. Phosphatidic acid species in linoleate-treated cells or muscle from insulin-resistant mice fed a safflower oil-based high-fat diet that was rich in linoleate were analysed by mass spectrometry. Linoleate pretreatment reduced IRS-1 tyrosine phosphorylation and p85 association. Overexpression of diacylglycerol kinase epsilon reversed the activation of protein kinase C isoforms by linoleate, but paradoxically further diminished IRS-1 tyrosine phosphorylation. Conversely, lisofylline treatment restored IRS-1 phosphorylation. Mass spectrometry indicated that the dilinoleoyl-phosphatidic acid content increased from undetectable levels to almost 20% of total phosphatidic acid in L6 cells and to 8% of total in the muscle of mice fed a high-fat diet. Micelles containing dilinoleoyl-phosphatidic acid specifically inhibited IRS-1 tyrosine phosphorylation and glycogen synthesis in L6 cells. These data indicate that linoleate-derived phosphatidic acid is a novel lipid species that contributes independently of protein kinase C to IRS-1 signalling defects in muscle cells in response to lipid

  12. Phosphatidic acid: biosynthesis, pharmacokinetics, mechanisms of action and effect on strength and body composition in resistance-trained individuals.

    PubMed

    Bond, Peter

    2017-01-01

    The mechanistic target of rapamycin complex 1 (mTORC1) has received much attention in the field of exercise physiology as a master regulator of skeletal muscle hypertrophy. The multiprotein complex is regulated by various signals such as growth factors, energy status, amino acids and mechanical stimuli. Importantly, the glycerophospholipid phosphatidic acid (PA) appears to play an important role in mTORC1 activation by mechanical stimulation. PA has been shown to modulate mTOR activity by direct binding to its FKBP12-rapamycin binding domain. Additionally, it has been suggested that exogenous PA activates mTORC1 via extracellular conversion to lysophosphatidic acid and subsequent binding to endothelial differentiation gene receptors on the cell surface. Recent trials have therefore evaluated the effects of PA supplementation in resistance-trained individuals on strength and body composition. As research in this field is rapidly evolving, this review attempts to provide a comprehensive overview of its biosynthesis, pharmacokinetics, mechanisms of action and effect on strength and body composition in resistance-trained individuals.

  13. Selective Cytotoxic Phospholipids for Prostate Cancer

    DTIC Science & Technology

    2005-10-01

    respectively. These agents were originally desingned as part of a series of compounds to inhibit lysophosphatidic acid (LPA), a phospholid growth...145 prostate caner cells respectively. These agents were originally desingned as part of a series of compounds to inhibit lysophosphatidic acid (LPA... Lysophosphatidic acid (LPA) and sphingosine or inhibit LPA or P13K signaling. 1-phosphate (SIP) are lipid mediators generated via the In a previous contribution

  14. relA-dependent RNA polymerase activity in Escherichia coli.

    PubMed Central

    Ryals, J; Bremer, H

    1982-01-01

    Parameters relating to RNA synthesis were measured after a temperature shift from 30 to 42 degrees C, in a relA+ and relA- isogenic pair of Escherichia coli strains containing a temperature-sensitive valyl tRNA synthetase. The following results were obtained: (i) the rRNA chain growth rate increased 2-fold in both strains; (ii) newly synthesized rRNA became unstable in both strains; (iii) the stable RNA gene activity (rRNA and tRNA, measured as stable RNA synthesis rate relative to the total instantaneous rate of RNA synthesis) decreased 1.7-fold in the relA+ strain and increased 1.9-fold in the relA mutant; and (iv) the RNA polymerase activity (measured by the percentage of total RNA polymerase enzyme active in transcription an any instant) decreased from 20 to 3.6% in the relA+ strain and remained unchanged (or increased at most to 22%) in the relA mutant. It is suggested that both rRNA gene activity and the RNA polymerase activity depend on the intracellular concentration of guanosine tetraphosphate, whereas the altered chain elongation rate and stability of rRNA are temperature or amino acid starvation effects, respectively, without involvement of relA function. PMID:6174501

  15. Folic Acid

    MedlinePlus

    Folic acid is used to treat or prevent folic acid deficiency. It is a B-complex vitamin needed by ... Folic acid comes in tablets. It usually is taken once a day. Follow the directions on your prescription label ...

  16. Aspartic acid

    MedlinePlus

    ... also called asparaginic acid. Aspartic acid helps every cell in the body work. It plays a role in: Hormone production and release Normal nervous system function Plant sources of aspartic acid include: Legumes such as ...

  17. Omega-3 fatty acids and other FFA4 agonists inhibit growth factor signaling in human prostate cancer cells.

    PubMed

    Liu, Ze; Hopkins, Mandi M; Zhang, Zhihong; Quisenberry, Chrystal B; Fix, Louise C; Galvan, Brianna M; Meier, Kathryn E

    2015-02-01

    Omega-3 fatty acids (n-3 FAs) are proposed to have many beneficial effects on human health. However, the mechanisms underlying their potential cancer preventative effects are unclear. G protein-coupled receptors (GPCRs) of the free fatty acid receptor (FFAR) family, FFA1/GPR40 and FFA4/GPR120, specifically bind n-3 FAs as agonist ligands. In this study, we examined the effects of n-3 FAs in human prostate cancer cell lines. Initial studies established that the long-chain n-3 FAs, eicosapentaenoic acid (EPA) and docosahexaenoic acid, inhibit proliferation of DU145 cells in response to lysophosphatidic acid (LPA), a mitogenic lipid mediator. When added alone to serum-starved DU145 cells, EPA transiently activates signaling events, including p70S6K phosphorylation. However, when added 15 minutes prior to LPA, EPA suppresses LPA-induced activating phosphorylations of ERK, FAK, and p70S6K, and expression of the matricellular protein CCN1. The rapid onset of the inhibitory action of EPA suggested involvement of a GPCR. Further studies showed that DU145 and PC-3 cells express mRNA and protein for both FFA4 and FFA1. TUG-891 (4-[(4-fluoro-4'-methyl[1,1'-biphenyl]-2-yl)methoxy]-benzenepropanoic acid), a selective agonist for FFA4, exerts inhibitory effects on LPA- and epidermal growth factor-induced proliferation and migration, similar to EPA, in DU145 and PC-3 cells. The effects of TUG-891 and EPA are readily reversible. The FFA1/FFA4 agonist GW9508 (4-[[(3-phenoxyphenyl)methyl]amino]-benzenepropranoic acid) likewise inhibits proliferation at doses that block FFA4. Knockdown of FFA4 expression prevents EPA- and TUG-891-induced inhibition of growth and migration. Together, these results indicate that activation of FFA4 initiates signaling events that can inhibit growth factor-induced signaling, providing a novel mechanism for suppression of cancer cell proliferation.

  18. Studies on the formation by rat brain preparations of CDP-diglyceride from CTP and phosphatidic acids of varying fatty acid compositions.

    PubMed

    Bishop, H H; Strickland, K P

    1976-03-01

    The enzyme, CTP:phosphatidate cytidylyltransferase (EC2.7.7.41) which catalyses formation of CDP-diglyceride from CTP and phosphatidic acid has been studied in rat brain preparations and other tissues. Improvement, as judged by the higher tissue activities obtained, in the assay method for this enzyme was achieved through use of phosphatidic acids sonicated in buffer-detergent solution saturated with ether and containing bovine serum albumin and use of short incubation times which essentially provided a measure of initial rates. The enzyme of rat brain microsomes yielded with 1,2-dioleolphosphatidic acid as substrate a pH optimum of 6.8 with maleate buffer and optimal concentrations of 60mM for MG2+, 6MM for CTP and 250 mug per 0.8 ml for phosphatidic acid. Enzyme activity was mainly located in the 90,000 X g fraction (microsomal) with small but significant activity in the 12,000 X g fraction. Comparison of activities (nanomoles CTP incorporated per milligram protein per minute) amongst tissues showed the following order: brain, 1.87; liver, 1.32; lung, 1.19; small intestine, 1.00; kidney, 0.69; heart, 0.41; diaphragm, 0.07; skeletal muscle, 0.02. Examination of the effect of varying the fatty acid composition in the phosphatidic acids added exogenously gave the following order (activities in parentheses); 1-stearoyl-2-oleoyl- (5.58), 1-oleoyl-2-stearoyl- (5.37), 1,2-dioleoyl- (4.49) 1-palmitoyl-2-oleoyl-(3.85), 1-stearoyl-2-arachidonoyl-(3.31), 1-arachidonoyl-2-stearoyl-(3.16), 1,2-diarachidonoyl-(0.72), 1,2-dicaproyl-(0.67), 1,2-dipalmitoyl-(0.67) and 1,2-distearoyl-(0.18). The single bis- and lysophosphatidic acids tested were inactive as substrates. Apart from a possible preference for one or more unsaturated fatty acids the transferase enzyme showed no selectivity in respect to the fatty acid distribution of phosphatidic acids.

  19. Acid Rain

    USGS Publications Warehouse

    Bricker, Owen P.; Rice, Karen C.

    1995-01-01

    Although acid rain is fading as a political issue in the United States and funds for research in this area have largely disappeared, the acidity of rain in the Eastern United States has not changed significantly over the last decade, and it continues to be a serious environmental problem. Acid deposition (commonly called acid rain) is a term applied to all forms of atmospheric deposition of acidic substances - rain, snow, fog, acidic dry particulates, aerosols, and acid-forming gases. Water in the atmosphere reacts with certain atmospheric gases to become acidic. For example, water reacts with carbon dioxide in the atmosphere to produce a solution with a pH of about 5.6. Gases that produce acids in the presence of water in the atmosphere include carbon dioxide (which converts to carbonic acid), oxides of sulfur and nitrogen (which convert to sulfuric and nitric acids}, and hydrogen chloride (which converts to hydrochloric acid). These acid-producing gases are released to the atmosphere through natural processes, such as volcanic emissions, lightning, forest fires, and decay of organic matter. Accordingly, precipitation is slightly acidic, with a pH of 5.0 to 5.7 even in undeveloped areas. In industrialized areas, most of the acid-producing gases are released to the atmosphere from burning fossil fuels. Major emitters of acid-producing gases include power plants, industrial operations, and motor vehicles. Acid-producing gases can be transported through the atmosphere for hundreds of miles before being converted to acids and deposited as acid rain. Because acids tend to build up in the atmosphere between storms, the most acidic rain falls at the beginning of a storm, and as the rain continues, the acids "wash out" of the atmosphere.

  20. Identification of bottlenecks in the accumulation of cyclic fatty acids in camelina seed oil.

    PubMed

    Yu, Xiao-Hong; Cahoon, Rebecca E; Horn, Patrick J; Shi, Hai; Prakash, Richa Rawat; Cai, Yuanheng; Hearney, Maegan; Chapman, Kent D; Cahoon, Edgar B; Schwender, Jorg; Shanklin, John

    2017-09-20

    Modified fatty acids (mFA) have diverse uses, e.g., cyclopropane fatty acids (CPA) are feedstocks for producing coatings, lubricants, plastics, and cosmetics. The expression of mFA-producing enzymes in crop and model plants generally results in lower levels of mFA accumulation than in their natural-occurring source plants. Thus, to further our understanding of metabolic bottlenecks that limit mFA accumulation, we generated transgenic Camelina sativa lines co-expressing Escherichia coli cyclopropane synthase (EcCPS) and Sterculia foetida lysophosphatidic acid acyltransferase (SfLPAT). In contrast to transgenic CPA-accumulating Arabidopsis, CPA accumulation in camelina caused only minor changes in seed weight, germination rate, oil accumulation, and seedling development. CPA accumulated to much higher levels in membrane than storage lipids, comprising more than 60% of total fatty acid in both phosphatidylcholine (PC) and phosphatidylethanolamine (PE) versus 26% in diacylglycerol (DAG) and 12% in triacylglycerol (TAG) indicating bottlenecks in the transfer of CPA from PC to DAG and from DAG to TAG. Upon coexpression of SfLPAT with EcCPS, di-CPA-PC increased by ~50% relative to lines expressing EcCPS alone with the di-CPA-PC primarily observed in the embryonic axis and mono-CPA-PC primarily in cotyledon tissue. EcCPS-SfLPAT lines revealed a redistribution of CPA from the sn-1 to sn-2 positions within PC and PE that was associated with a doubling of CPA accumulation in both DAG and TAG. The identification of metabolic bottlenecks in acyl transfer between site of synthesis (phospholipids) and deposition in storage oils (TAGs) lays the foundation for the optimizing CPA accumulation through directed engineering of oil synthesis in target crops. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

  1. Molecular cloning of magnesium-independent type 2 phosphatidic acid phosphatases from airway smooth muscle.

    PubMed

    Tate, R J; Tolan, D; Pyne, S

    1999-07-01

    Members of the type 2 phosphatidic acid phosphatase (PAP2) family catalyse the dephosphorylation of phosphatidic acid (PA), lysophosphatidate and sphingosine 1-phosphate. Here, we demonstrate the presence of a Mg(2+)-independent and N-ethymaleimide-insensitive PAP2 activity in cultured guinea-pig airway smooth muscle (ASM) cells. Two PAP2 cDNAs of 923 and 926 base pairs were identified and subsequently cloned from these cells. The ORF of the 923 base pair cDNA encoded a protein of 285 amino acids (Mr = 32.1 kDa), which had 94% homology with human PAP2a (hPAP2a) and which probably represents a guinea-pig specific PAP2a (gpPAP2a1). The ORF of the 926 base pair cDNA encoded a protein of 286 amino acids (Mr = 32.1 kDa) which had 84% and 91% homology with hPAP2a and gpPAP2a1, respectively. This protein, termed gpPAP2a2, has two regions (aa 21-33 and 51-74) of marked divergence and altered hydrophobicity compared with hPAP2a and gpPAP2a1. This occurs in the predicted first and second transmembrane domains and at the extremes of the first outer loop. Other significant differences between gpPAP2a1/2 and hPAP2a, hPAP2b and hPAP2c occur at the cytoplasmic C-terminal. Transient expression of gpPAP2a2 in Cos-7 cells resulted in an approx. 4-fold increase in Mg(2+)-independent PAP activity, thereby confirming that gpPAP2a2 is another catalytically active member of an extended PAP2 family.

  2. Acid Rain.

    ERIC Educational Resources Information Center

    Openshaw, Peter

    1987-01-01

    Provides some background information on acid deposition. Includes a historical perspective, describes some effects of acid precipitation, and discusses acid rain in the United Kingdom. Contains several experiments that deal with the effects of acid rain on water quality and soil. (TW)

  3. Acid Rain.

    ERIC Educational Resources Information Center

    Openshaw, Peter

    1987-01-01

    Provides some background information on acid deposition. Includes a historical perspective, describes some effects of acid precipitation, and discusses acid rain in the United Kingdom. Contains several experiments that deal with the effects of acid rain on water quality and soil. (TW)

  4. Benzyl and Naphthalene-Methyl Phosphonic Acid Inhibitors of Autotaxin with Anti-invasive and Anti-metastatic Actions

    PubMed Central

    Gupte, Renuka; Patil, Renukadevi; Liu, Jianxiong; Wang, Yaohong; Lee, Sue C.; Fujiwara, Yuko; Fells, James; Bolen, Alyssa L.; Emmons-Thompson, Karin; Yates, C. Ryan; Siddam, Anjaih; Panupinthu, Nattapon; Pham, Truc-Chi T.; Baker, Daniel L.; Parrill, Abby L.; Mills, Gordon B.; Tigyi, Gabor

    2012-01-01

    Autotaxin (ATX, NPP2) is a member of the nucleotide pyrophosphate phosphodiesterase enzyme family. ATX catalyzes the hydrolytic cleavage of lysophosphatidylcholine (LPC) via a lysophospholipase D activity that leads to the generation of the growth factor-like lipid mediator lysophosphatidic acid (LPA). ATX is highly upregulated in metastatic and chemotherapy-resistant carcinomas and represents a potential target to mediate cancer invasion and metastasis. Here we report the synthesis and pharmacological characterization of inhibitors of ATX based on the 4-tetradecanoylaminobenzyl phosphonic acid scaffold that was previously found to lack sufficient stability in cellular systems. The new 4-substituted benzyl phosphonic acid and 6-substituted naphthalen-2-yl-methyl phosphonic acid analogs blocked ATX with Ki values in the low-micromolar-nanomolar range against FS-3, LPC, and nucleotide substrates through a mixed-mode mechanism of inhibition. None of the compounds tested inhibited the activity of related enzymes (NPP6 and NPP7). In addition, the compounds were evaluated as agonists or antagonists of seven LPA receptor subtypes. Analogs 22 and 30b, the two most potent ATX inhibitors, dose-dependently inhibited the invasion of MM1 hepatoma cells across murine mesothelial and human vascular endothelial monolayers in vitro. The average terminal half-life for compound 22 was 10h ± 5.4h and it caused a long-lasting reduction plasma LPA levels. Compounds 22 and 30b significantly reduced lung metastasis of B16-F10 syngeneic mouse melanoma in a post-inoculation treatment paradigm. The described 4-substituted benzyl phosphonic acids and 6-substituted naphthalen-2-yl-methyl phosphonic acids represent new lead compounds that effectively inhibit the ATX-LPA-LPA receptor axis both in vitro and in vivo. PMID:21465666

  5. Mutations in the Prokaryotic Pathway Rescue the fatty acid biosynthesis1 Mutant in the Cold.

    PubMed

    Gao, Jinpeng; Wallis, James G; Browse, John

    2015-09-01

    The Arabidopsis (Arabidopsis thaliana) fatty acid biosynthesis1 (fab1) mutant has increased levels of the saturated fatty acid 16:0 due to decreased activity of 3-ketoacyl-acyl carrier protein (ACP) synthase II. In fab1 leaves, phosphatidylglycerol, the major chloroplast phospholipid, contains up to 45% high-melting-point molecular species (molecules that contain only 16:0, 16:1-trans, and 18:0), a trait associated with chilling-sensitive plants, compared with less than 10% in wild-type Arabidopsis. Although they do not exhibit typical chilling sensitivity, when exposed to low temperatures (2°C-6°C) for long periods, fab1 plants do suffer collapse of photosynthesis, degradation of chloroplasts, and eventually death. A screen for suppressors of this low-temperature phenotype has identified 11 lines, some of which contain additional alterations in leaf-lipid composition relative to fab1. Here, we report the identification of two suppressor mutations, one in act1, which encodes the chloroplast acyl-ACP:glycerol-3-phosphate acyltransferase, and one in lpat1, which encodes the chloroplast acyl-ACP:lysophosphatidic acid acyltransferase. These enzymes catalyze the first two steps of the prokaryotic pathway for glycerolipid synthesis, so we investigated whether other mutations in this pathway would rescue the fab1 phenotype. Both the gly1 mutation, which reduces glycerol-3-phosphate supply to the prokaryotic pathway, and fad6, which is deficient in the chloroplast 16:1/18:1 fatty acyl desaturase, were discovered to be suppressors. Analyses of leaf-lipid compositions revealed that mutations at all four of the suppressor loci result in reductions in the proportion of high-melting-point molecular species of phosphatidylglycerol relative to fab1. We conclude that these reductions are likely the basis for the suppressor phenotypes. © 2015 American Society of Plant Biologists. All Rights Reserved.

  6. High specificity of human secretory class II phospholipase A2 for phosphatidic acid.

    PubMed

    Snitko, Y; Yoon, E T; Cho, W

    1997-02-01

    Lysophosphatidic acid (LPA) is a potent lipid second messenger which stimulates platelet aggregation, cell proliferation and smooth-muscle contraction. The phospholipase A2 (PLA2)-catalysed hydrolysis of phosphatidic acid (PA) is thought to be a primary synthetic route for LPA. Of the multiple forms of PLA2 present in human tissues, human secretory class-II PLA2 (hs-PLA2) has been implicated in the production of LPA from platelets and whole blood cells challenged with inflammatory stimuli. To explore further the possibility that hs-PLA2 is involved in the production of LPA, we rigorously measured the phospholipid head group specificity of hs-PLA2 by a novel PLA2 kinetic system using polymerized mixed liposomes. Kinetic analysis of recombinant hs-PLA2 demonstrates that hs-PLA2 strongly prefers PA as substrate over other phospholipids found in the mammalian plasma membrane including phosphatidylserine (PS), phosphatidylcholine (PC) and phosphatidylethanolamine (PE). The order of preference is PA > PE approximately PS > PC. To identify amino acid residues of hs-PLA2 that are involved in its unique substrate specificity, we mutated two residues, Glu-56 and Lys-69, which were shown to interact with the phospholipid head group in the X-ray-crystallographic structure of the hs-PLA2-transition-state-analogue complex. The K69Y mutant showed selective inactivation toward PA whereas the E56K mutant displayed a most pronounced inactivation to PE. Thus it appears that Lys-69 is at least partially involved in the PA specificity of hs-PLA2 and Glu-56 in the distinction between PE and PC. In conjunction with a recent cell study [Fourcade, Simon, Viode, Rugani, Leballe, Ragab, Fournie, Sarda and Chap (1995) Cell 80, 919-927], these studies suggest that hs-PLA2 can rapidly hydrolyse PA molecules exposed to the outer layer of cell-derived microvesicles and thereby produce LPA.

  7. Fatty acid composition of muscle fat and enzymes of storage lipid synthesis in whole muscle from beef cattle.

    PubMed

    Kazala, E Chris; Lozeman, Fred J; Mir, Priya S; Aalhus, Jennifer L; Schmutz, Sheila M; Weselake, Randall J

    2006-11-01

    Enhanced intramuscular fat content (i.e., marbling) in beef is a desirable trait, which can result in increased product value. This study was undertaken with the aim of revealing biochemical factors associated with the marbling trait in beef cattle. Samples of longissimus lumborum (LL) and pars costalis diaphragmatis (PCD) were taken from a group of intact crossbred males and females at slaughter, lipids extracted, and the resulting FAME examined for relationships with marbling fat deposition. For LL, significant associations were found between degree of marbling and myristic (14:0, r = 0.55, P < 0.01), palmitic (16:0, r = 0.80, P < 0.001), stearic (18:0, r = -0.58, P < 0.01), and oleic (18:1c-9, r = 0.79, P < 0.001) acids. For PCD, significant relationships were found between marbling and palmitic (r = 0.71, P < 0.001) and oleic (r = 0.74, P < 0.001) acids. Microsomal fractions prepared from PCD muscle were assayed for diacylglycerol acyltransferase (DGAT), lysophosphatidic acid acyltransferase (LPAAT), and phosphatidic acid phosphatase-1 (PAP-1) activity, and the results examined for relationships with degree of intramuscular fat deposition. None of the enzyme activities from PCD displayed an association with marbling fat content, but DGAT specific activity showed significant positive associations with LPAAT (r = 0.54, P < 0.01), total PAP (r = 0.66, P < 0.001), and PAP-1 (r = 0.63, P < 0.01) specific activities. The results on FA compositions of whole muscle tissues provide insight into possible enzyme action associated with the production of specific FA. The increased proportion of oleic acid associated with enhanced lipid content of whole muscle is noteworthy given the known health benefits of this FA.

  8. Acid rain

    SciTech Connect

    Stensland, G.J.

    1983-11-01

    A series of definitions for the field of acid rain studies are presented. Protocols for acid rain sampling and monitoring are also presented. A procedure for calculatory precipitation pH is discussed. 11 references, 1 table.

  9. Folic acid

    MedlinePlus

    ... of childhood cancer of the white blood cells. Iron deficiency. Taking folic acid with iron supplements is not ... supplements without folic acid for treating and preventing iron deficiency and anemia caused by too little iron in ...

  10. Aminocaproic Acid

    MedlinePlus

    Aminocaproic acid is used to control bleeding that occurs when blood clots are broken down too quickly. This type ... the baby is ready to be born). Aminocaproic acid is also used to control bleeding in the ...

  11. Obeticholic Acid

    MedlinePlus

    Obeticholic acid is used alone or in combination with ursodiol (Actigall, Urso) to treat primary biliary cholangitis (PBC; a ... were not treated successfully with ursodiol alone. Obeticholic acid is in a class of medications called farnesoid ...

  12. Acid mucopolysaccharides

    MedlinePlus

    ... this page: //medlineplus.gov/ency/article/003368.htm Acid mucopolysaccharides To use the sharing features on this page, please enable JavaScript. Acid mucopolysaccharides is a test that measures the amount ...

  13. Ethacrynic Acid

    MedlinePlus

    Ethacrynic acid, a 'water pill,' is used to treat swelling and fluid retention caused by various medical problems. It ... Ethacrynic acid comes as a tablet to take by mouth. It is usually taken once or twice a day ...

  14. Ascorbic Acid

    MedlinePlus

    Ascorbic acid is used to prevent and treat scurvy, a disease caused by a lack of vitamin C in ... Ascorbic acid comes in extended-release (long-acting) capsules and tablets, lozenges, syrup, chewable tablets, and liquid drops to ...

  15. Aristolochic Acids

    MedlinePlus

    ... Sciences NIH-HHS www.niehs.nih.gov Aristolochic Acids Key Points Report on Carcinogens Status Known to be human carcinogens Aristolochia Clematitis Aristolochic Acids n Known human carcinogens n Found in certain ...

  16. Amino acids

    MedlinePlus

    ... this page: //medlineplus.gov/ency/article/002222.htm Amino acids To use the sharing features on this page, please enable JavaScript. Amino acids are organic compounds that combine to form proteins . ...

  17. Mefenamic Acid

    MedlinePlus

    Mefenamic acid is used to relieve mild to moderate pain, including menstrual pain (pain that happens before or during a menstrual period). Mefenamic acid is in a class of medications called NSAIDs. ...

  18. Valproic Acid

    MedlinePlus

    Valproic acid is used alone or with other medications to treat certain types of seizures. Valproic acid is also used to treat mania (episodes of ... to relieve headaches that have already begun. Valproic acid is in a class of medications called anticonvulsants. ...

  19. Fatty acids - trans fatty acids

    USDA-ARS?s Scientific Manuscript database

    The data supporting a negative effect of dietary trans fatty acids on cardiovascular disease risk is consistent. The primary dietary sources of trans fatty acids include partially hydrogenated fat and rudiment fat. The adverse effect of trans fatty acids on plasma lipoprotein profiles is consisten...

  20. GP140/CDCPI in the Development of Prostate Cancer Metastasis

    DTIC Science & Technology

    2012-05-01

    Activated Receptors (PARs) in the GPCR family (Reviewed in [5]. We found that lysophosphatidic acid (LPA, 5 M) or sphingosine 1 phosphate (SIP1, 2 M) both...Biol 9 (2008) 730-736. [7] Y. Zhao, V. Natarajan, Lysophosphatidic acid signaling in airway epithelium: role in airway inflammation and remodeling, Cell Signal 21 (2009) 367-377. APPENDICES None

  1. Redundant Systems of Phosphatidic Acid Biosynthesis via Acylation of Glycerol-3-Phosphate or Dihydroxyacetone Phosphate in the Yeast Saccharomyces cerevisiae

    PubMed Central

    Athenstaedt, Karin; Weys, Sabine; Paltauf, Fritz; Daum, Günther

    1999-01-01

    In the yeast Saccharomyces cerevisiae lipid particles harbor two acyltransferases, Gat1p and Slc1p, which catalyze subsequent steps of acylation required for the formation of phosphatidic acid. Both enzymes are also components of the endoplasmic reticulum, but this compartment contains additional acyltransferase(s) involved in the biosynthesis of phosphatidic acid (K. Athenstaedt and G. Daum, J. Bacteriol. 179:7611–7616, 1997). Using the gat1 mutant strain TTA1, we show here that Gat1p present in both subcellular fractions accepts glycerol-3-phosphate and dihydroxyacetone phosphate as a substrate. Similarly, the additional acyltransferase(s) present in the endoplasmic reticulum can acylate both precursors. In contrast, yeast mitochondria harbor an enzyme(s) that significantly prefers dihydroxyacetone phosphate as a substrate for acylation, suggesting that at least one additional independent acyltransferase is present in this organelle. Surprisingly, enzymatic activity of 1-acyldihydroxyacetone phosphate reductase, which is required for the conversion of 1-acyldihydroxyacetone phosphate to 1-acylglycerol-3-phosphate (lysophosphatidic acid), is detectable only in lipid particles and the endoplasmic reticulum and not in mitochondria. In vivo labeling of wild-type cells with [2-3H, U-14C]glycerol revealed that both glycerol-3-phosphate and dihydroxyacetone phosphate can be incorporated as a backbone of glycerolipids. In the gat1 mutant and the 1-acylglycerol-3-phosphate acyltransferase slc1 mutant, the dihydroxyacetone phosphate pathway of phosphatidic acid biosynthesis is slightly preferred as compared to the wild type. Thus, mutations of the major acyltransferases Gat1p and Slc1p lead to an increased contribution of mitochondrial acyltransferase(s) to glycerolipid synthesis due to their substrate preference for dihydroxyacetone phosphate. PMID:10049376

  2. Phosphatidic acid mediates activation of mTORC1 through the ERK signaling pathway

    PubMed Central

    Winter, Jeremiah N.; Fox, Todd E.; Kester, Mark; Jefferson, Leonard S.

    2010-01-01

    The mammalian target of rapamycin (mTOR) assembles into two distinct multiprotein complexes known as mTORC1 and mTORC2. Of the two complexes, mTORC1 acts to integrate a variety of positive and negative signals to downstream targets that regulate cell growth. The lipid second messenger, phosphatidic acid (PA), represents one positive input to mTORC1, and it is thought to act by binding directly to mTOR, thereby enhancing the protein kinase activity of mTORC1. Support for this model includes findings that PA binds directly to mTOR and addition of PA to the medium of cells in culture results in activation of mTORC1. In contrast, the results of the present study do not support a model in which PA activates mTORC1 through direct interaction with the protein kinase but, instead, show that the lipid promotes mTORC1 signaling through activation of the ERK pathway. Moreover, rather than acting directly on mTORC1, the results suggest that exogenous PA must be metabolized to lysophosphatidic acid (LPA), which subsequently activates the LPA receptor endothelial differentiation gene (EDG-2). Finally, in contrast to previous studies, the results of the present study demonstrate that leucine does not act through phospholipase D and PA to activate mTORC1 and, instead, show that the two mediators act through parallel upstream signaling pathways to activate mTORC1. Overall, the results demonstrate that leucine and PA signal through parallel pathways to activate mTORC1 and that PA mediates its effect through the ERK pathway, rather than through direct binding to mTOR. PMID:20427710

  3. Acid rain

    SciTech Connect

    White, J.C. )

    1988-01-01

    This book presents the proceedings of the third annual conference sponsored by the Acid Rain Information Clearinghouse (ARIC). Topics covered include: Legal aspects of the source-receptor relationship: an energy perspective; Scientific uncertainty, agency inaction, and the courts; and Acid rain: the emerging legal framework.

  4. Acid rain

    SciTech Connect

    Elsworth, S.

    1985-01-01

    This book was written in a concise and readable style for the lay public. It's purpose was to make the public aware of the damage caused by acid rain and to mobilize public opinion to favor the elimination of the causes of acid rain.

  5. Acid clusters

    SciTech Connect

    Keesee, R.G.; Castleman, A.W. Jr.

    1986-04-01

    Molecular clusters can be considered to be the smallest size range of an aerosol particle size distribution. Nucleation from the gas phase to particles or droplets involves the formation of clusters in the initial stages. Consequently, knowledge of the properties and formation of clusters containing acids contribute to an understanding of acid rain. This paper presents an overview of results obtained in the laboratory on the formation and stability of both neutral and ionized acid clusters. With free jet expansion techniques, the authors have produced clusters of aqueous nitric acid, aqueous hydrochloric acid, aqueous sulfuric acid, acetic acid and aqueous sulfur dioxide. For analogy to buffering, the formation of clusters containing ammonia have also been examined. These have included ammonia with aqueous nitric acid, hydrogen sulfide and sulfur dioxide. The basic experiment involves expansion of vapor through a nozzle, collimation of the jet with a skimmer to form a well-directed molecular beam, and detection of clusters via electron impact ionization and mass spectrometry. Some variations include the introduction of a reactive gas into vacuum near the expansion as described elsewhere and the implementation of an electrostatic quadrupolar field to examine the polarity of the neutral clusters.

  6. Acid rain

    SciTech Connect

    Sweet, W.

    1980-06-20

    Acid precipitation includes not only rain but also acidified snow, hail and frost, as well as sulfur and nitrogen dust. The principal source of acid precipitation is pollution emitted by power plants and smelters. Sulfur and nitrogen compounds contained in the emissions combine with moisture to form droplets with a high acid content - sometimes as acidic as vinegar. When sufficiently concentrated, these acids can kill fish and damage material structures. Under certain circumstances they may reduce crop and forest yields and cause or aggravate respiratory diseases in humans. During the summer, especially, pollutants tend to collect over the Great Lakes in high pressure systems. Since winds typically are westerly and rotate clockwise around high pressure systems, the pollutants gradually are dispersed throughout the eastern part of the continent.

  7. Asparagusic acid.

    PubMed

    Mitchell, Stephen C; Waring, Rosemary H

    2014-01-01

    Asparagusic acid (1,2-dithiolane-4-carboxylic acid) is a simple sulphur-containing 5-membered heterocyclic compound that appears unique to asparagus, though other dithiolane derivatives have been identified in non-food species. This molecule, apparently innocuous toxicologically to man, is the most probable culprit responsible for the curious excretion of odorous urine following asparagus ingestion. The presence of the two adjacent sulphur atoms leads to an enhanced chemical reactivity, endowing it with biological properties including the ability to substitute potentially for α-lipoic acid in α-keto-acid oxidation systems. This brief review collects the scattered data available in the literature concerning asparagusic acid and highlights its properties, intermediary metabolism and exploratory applications.

  8. Mutations in the Prokaryotic Pathway Rescue the fatty acid biosynthesis1 Mutant in the Cold1[OPEN

    PubMed Central

    Gao, Jinpeng; Wallis, James G.; Browse, John

    2015-01-01

    The Arabidopsis (Arabidopsis thaliana) fatty acid biosynthesis1 (fab1) mutant has increased levels of the saturated fatty acid 16:0 due to decreased activity of 3-ketoacyl-acyl carrier protein (ACP) synthase II. In fab1 leaves, phosphatidylglycerol, the major chloroplast phospholipid, contains up to 45% high-melting-point molecular species (molecules that contain only 16:0, 16:1-trans, and 18:0), a trait associated with chilling-sensitive plants, compared with less than 10% in wild-type Arabidopsis. Although they do not exhibit typical chilling sensitivity, when exposed to low temperatures (2°C–6°C) for long periods, fab1 plants do suffer collapse of photosynthesis, degradation of chloroplasts, and eventually death. A screen for suppressors of this low-temperature phenotype has identified 11 lines, some of which contain additional alterations in leaf-lipid composition relative to fab1. Here, we report the identification of two suppressor mutations, one in act1, which encodes the chloroplast acyl-ACP:glycerol-3-phosphate acyltransferase, and one in lpat1, which encodes the chloroplast acyl-ACP:lysophosphatidic acid acyltransferase. These enzymes catalyze the first two steps of the prokaryotic pathway for glycerolipid synthesis, so we investigated whether other mutations in this pathway would rescue the fab1 phenotype. Both the gly1 mutation, which reduces glycerol-3-phosphate supply to the prokaryotic pathway, and fad6, which is deficient in the chloroplast 16:1/18:1 fatty acyl desaturase, were discovered to be suppressors. Analyses of leaf-lipid compositions revealed that mutations at all four of the suppressor loci result in reductions in the proportion of high-melting-point molecular species of phosphatidylglycerol relative to fab1. We conclude that these reductions are likely the basis for the suppressor phenotypes. PMID:26224803

  9. Acid fog

    SciTech Connect

    Hileman, B.

    1983-03-01

    Fog in areas of southern California previously thought to be pollution-free has been shown to have a pH as low as 1.69. It has been found to be most acidic after smoggy days, suggesting that it forms on the aerosol associated with the previously exiting smog. Studies on Whiteface Mountain in the Adirondacks show that fog water is often 10 times as acidic as rainwater. As a result of their studies, California plans to spend $4 million on acid deposition research in the coming year. (JMT)

  10. Acid Precipitation

    ERIC Educational Resources Information Center

    Likens, Gene E.

    1976-01-01

    Discusses the fact that the acidity of rain and snow falling on parts of the U.S. and Europe has been rising. The reasons are still not entirely clear and the consequences have yet to be well evaluated. (MLH)

  11. Folic Acid

    MedlinePlus

    ... folic acid can hide signs that you lack vitamin B12, which can cause nerve damage. 10 Do I ... Rosenberg, I.H., et al. (2007). Folate and vitamin B12 status in relation to anemia, macrocytosis and cognitive ...

  12. Tranexamic Acid

    MedlinePlus

    ... is used to treat heavy bleeding during the menstrual cycle (monthly periods) in women. Tranexamic acid is in ... tablets for more than 5 days in a menstrual cycle or take more than 6 tablets in a ...

  13. Acid Precipitation

    ERIC Educational Resources Information Center

    Likens, Gene E.

    1976-01-01

    Discusses the fact that the acidity of rain and snow falling on parts of the U.S. and Europe has been rising. The reasons are still not entirely clear and the consequences have yet to be well evaluated. (MLH)

  14. Acidic precipitation

    SciTech Connect

    Martin, H.C.

    1987-01-01

    At the International Symposium on Acidic Precipitation, over 400 papers were presented, and nearly 200 of them are included here. They provide an overview of the present state of the art of acid rain research. The Conference focused on atmospheric science (monitoring, source-receptor relationships), aquatic effects (marine eutrophication, lake acidification, impacts on plant and fish populations), and terrestrial effects (forest decline, soil acidification, etc.).

  15. Fatty acid distribution and lipid metabolism in developing seeds of laurate-producing rape (Brassica napus L.).

    PubMed

    Wiberg, E; Banas, A; Stymne, S

    1997-01-01

    The fatty acid composition and content of membrane and storage lipids of two transgenic laurate-producing rape (Brassica napus L.) lines were monitored during seed development. The two lines, the medium-laurate (ML) line and the high-laurate (HL) line, accumulated 34 mol% and 55 mol% of laurate in their seed triacylglycerols, respectively. The diacylglycerols contained about 17 and 33 mol% of laurate in the ML- and HL-lines, respectively, from the mid-stage of seed development up to seed maturity. The ML-line showed a maximal relative laurate content in phosphatidylcholine (17 mol%) at the mid-stage of seed development whereafter the content decreased to 2.7 mol% with seed maturity. The laurate content in phosphatidylcholine was observed to remain high (26 mol%) in the HL-line from the mid-stage to the end of triacylglycerol deposition. Thereafter, the relative content decreased and reached 6.6 mol% in the mature seeds. There was an enhanced activity of lauroyl-phosphatidylcholine-metabolizing enzymes in the seed membranes from laurate-producing lines compared with control lines, which might explain the decrease seen in laurate content in phosphatidylcholine during seed maturation. A comparison of the laurate distribution in the lipids from developing laurate-producing rape seeds and developing seeds from three species naturally accumulating laurate at similar levels revealed differences in laurate metabolism compared with these species. The results suggest that phospholipids and triacylglycerols are synthesized from the same diacylglycerol pool in rape seeds and that rape lysophosphatidic acid acyltransferase and diacylglycerol acyltransferase do not have the same preference for laurate substrates as the corresponding enzymes in seed tissues naturally accumulating this acyl group. In addition, the mechanisms that specifically remove or exclude laurate from membrane lipids appear less effective in rape seed than in tissues naturally evolved to synthesize laurate

  16. Acid Rain

    USGS Publications Warehouse

    Bricker, Owen P.; Rice, Karen C.

    1993-01-01

    Acid deposition, or acid rain as it is more commonly referred to, has become a widely publicized environmental issue in the U.S. over the past decade. The term usually conjures up images of fish kills, dying forests, "dead" lakes, and damage to monuments and other historic artifacts. The primary cause of acid deposition is emission of S02 and NOx to the atmosphere during the combustion of fossil fuels. Oxidation of these compounds in the atmosphere forms strong acids - H2SO4 and HNO3 - which are returned to the Earth in rain, snow, fog, cloud water, and as dry deposition.Although acid deposition has only recently been recognized as an environmental problem in the U.S., it is not a new phenomenon (Cogbill & Likens 1974). As early as the middle of the 17th century in England, the deleterious effects of industrial emissions on plants, animals, and humans, and the atmospheric transport of pollutants between England and France had become issues of concern (Evelyn 1661, Graunt 1662). It is interesting that well over three hundred years ago in England, recommendations were made to move industry outside of towns and build higher chimneys to spread the pollution into "distant parts." Increasing the height of smokestacks has helped alleviate local problems, but has exacerbated others. In the U.S. the height of the tallest smokestack has more than doubled, and the average height of smokestacks has tripled since the 1950s (Patrick et al 1981). This trend occurred in most industrialized nations during the 20th century and has had the effect of transforming acid rain from a local urban problem into a problem of global scale.

  17. Acid Rain

    USGS Publications Warehouse

    Bricker, Owen P.; Rice, Karen C.; Dietrich, W.E.; Sposito, Garrison

    1997-01-01

    Acid deposition, or acid rain as it is more commonly referred to, has become a widely publicized environmental issue in the U.S. over the past decade. The term usually conjures up images of fish kills, dying forests, "dead" lakes, and damage to monuments and other historic artifacts. The primary cause of acid deposition is emission of S02 and NOx to the atmosphere during the combustion of fossil fuels. Oxidation of these compounds in the atmosphere forms strong acids - H2SO4 and HNO3 - which are returned to the Earth in rain, snow, fog, cloud water, and as dry deposition.Although acid deposition has only recently been recognized as an environmental problem in the U.S., it is not a new phenomenon (Cogbill & Likens 1974). As early as the middle of the 17th century in England, the deleterious effects of industrial emissions on plants, animals, and humans, and the atmospheric transport of pollutants between England and France had become issues of concern (Evelyn 1661, Graunt 1662). It is interesting that well over three hundred years ago in England, recommendations were made to move industry outside of towns and build higher chimneys to spread the pollution into "distant parts." Increasing the height of smokestacks has helped alleviate local problems, but has exacerbated others. In the U.S. the height of the tallest smokestack has more than doubled, and the average height of smokestacks has tripled since the 1950s (Patrick et al 1981). This trend occurred in most industrialized nations during the 20th century and has had the effect of transforming acid rain from a local urban problem into a problem of global scale.

  18. Salicylic acids

    PubMed Central

    Hayat, Shamsul; Irfan, Mohd; Wani, Arif; Nasser, Alyemeni; Ahmad, Aqil

    2012-01-01

    Salicylic acid is well known phytohormone, emerging recently as a new paradigm of an array of manifestations of growth regulators. The area unleashed yet encompassed the applied agriculture sector to find the roles to strengthen the crops against plethora of abiotic and biotic stresses. The skipped part of integrated picture, however, was the evolutionary insight of salicylic acid to either allow or discard the microbial invasion depending upon various internal factors of two interactants under the prevailing external conditions. The metabolic status that allows the host invasion either as pathogenesis or symbiosis with possible intermediary stages in close systems has been tried to underpin here. PMID:22301975

  19. Acid rain

    SciTech Connect

    Not Available

    1984-06-01

    An overview is presented of acid rain and the problems it causes to the environment worldwide. The acidification of lakes and streams is having a dramatic effect on aquatic life. Aluminum, present in virtually all forest soils, leaches out readily under acid conditions and interferes with the gills of all fish, some more seriously than others. There is evidence of major damage to forests in European countries. In the US, the most severe forest damage appears to be in New England, New York's Adirondacks, and the central Appalachians. This small region is part of a larger area of the Northeast and Canada that appears to have more acid rainfall than the rest of the country. It is downwind from major coal burning states, which produce about one quarter of US SO/sub 2/ emissions and one sixth of nitrogen oxide emissions. Uncertainties exist over the causes of forest damage and more research is needed before advocating expensive programs to reduce rain acidity. The President's current budget seeks an expansion of research funds from the current $30 million per year to $120 million.

  20. Acrylic acid

    Integrated Risk Information System (IRIS)

    Acrylic acid ( CASRN 79 - 10 - 7 ) Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments for Noncarcinogenic Eff

  1. Cacodylic acid

    Integrated Risk Information System (IRIS)

    Cacodylic acid ; CASRN 75 - 60 - 5 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments for Noncarcinogenic Eff

  2. Trichloroacetic acid

    Integrated Risk Information System (IRIS)

    EPA / 635 / R - 09 / 003F www.epa.gov / iris TOXICOLOGICAL REVIEW OF TRICHLOROACETIC ACID ( CAS No . 76 - 03 - 9 ) In Support of Summary Information on the Integrated Risk Information System ( IRIS ) September 2011 U.S . Environmental Protection Agency Washington , DC ii DISCLAIMER This document has

  3. Benzoic acid

    Integrated Risk Information System (IRIS)

    Benzoic acid ; CASRN 65 - 85 - 0 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments for Noncarcinogenic Effec

  4. Formic acid

    Integrated Risk Information System (IRIS)

    Formic acid ; CASRN 64 - 18 - 6 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments for Noncarcinogenic Effect

  5. Phosphoric acid

    Integrated Risk Information System (IRIS)

    Phosphoric acid ; CASRN 7664 - 38 - 2 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments for Noncarcinogenic

  6. Selenious acid

    Integrated Risk Information System (IRIS)

    Selenious acid ; CASRN 7783 - 00 - 8 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments for Noncarcinogenic E

  7. Dichloroacetic acid

    Integrated Risk Information System (IRIS)

    EPA 635 / R - 03 / 007 www.epa.gov / iris TOXICOLOGICAL REVIEW OF DICHLOROACETIC ACID ( CAS No . 79 - 43 - 6 ) In Support of Summary Information on the Integrated Risk Information System ( IRIS ) August 2003 U.S . Environmental Protection Agency Washington , DC DISCLAIMER This document has been

  8. Azelaic acid.

    PubMed

    Nazzaro-Porro, M

    1987-12-01

    This review is an update on the literature accumulated over the past 10 years following the original observation that azelaic acid, a naturally occurring and nontoxic C9 dicarboxylic acid, possesses significant biologic properties and a potential as a therapeutic agent. These studies have shown that azelaic acid is a reversible inhibitor of tyrosinase and other oxidoreductases in vitro and that it inhibits mitochondrial respiration. It can also inhibit anaerobic glycolysis. Both in vitro and in vivo it has an antimicrobial effect on both aerobic and anaerobic (Propionibacterium acnes) microorganisms. In tissue culture it exerts a dose- and time-dependent cytotoxic effect on malignant melanocytes, associated with mitochondrial damage and inhibition of deoxyribonucleic acid (DNA) synthesis. Tumoral cell lines not containing tyrosinase are equally affected. Normal cells in culture exposed to the same concentrations of the diacid that are toxic for tumoral cells are in general not damaged. Radioactive azelaic acid has been shown to penetrate tumoral cells at a higher level than normal cells of the corresponding line. Topically applied (a 20% cream), it has been shown to be of therapeutic value in skin disorders of different etiologies. Its beneficial effect on various forms of acne (comedogenic, papulopustular, nodulocystic) has been clearly demonstrated. Particularly important is its action on abnormal melanocytes, which has led to the possibility of obtaining good results on melasma and highly durable therapeutic responses on lentigo maligna. It is also capable of causing regression of cutaneous malignant melanoma, but its role in melanoma therapy remains to be investigated.(ABSTRACT TRUNCATED AT 250 WORDS)

  9. 38 CFR 21.422 - Reduction in subsistence allowance following the loss of a dependent.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 38 Pensions, Bonuses, and Veterans' Relief 2 2010-07-01 2010-07-01 false Reduction in subsistence... and Employment Under 38 U.S.C. Chapter 31 Informing the Veteran § 21.422 Reduction in subsistence allowance following the loss of a dependent. (a) Notice of reduction required when a veteran loses a...

  10. ASIC2a-dependent increase of ASIC3 surface expression enhances the sustained component of the currents

    PubMed Central

    Kweon, Hae-Jin; Cho, Jin-Hwa; Jang, Il-Sung; Suh, Byung-Chang

    2016-01-01

    Acid-sensing ion channels (ASICs) are proton-gated cation channels widely expressed in the nervous system. Proton sensing by ASICs has been known to mediate pain, mechanosensation, taste transduction, learning and memory, and fear. In this study, we investigated the differential subcellular localization of ASIC2a and ASIC3 in heterologous expression systems. While ASIC2a targeted the cell surface itself, ASIC3 was mostly accumulated in the ER with partial expression in the plasma membrane. However, when ASIC3 was co-expressed with ASIC2a, its surface expression was markedly increased. By using bimolecular fluorescence complementation (BiFC) assay, we confirmed the heteromeric association between ASIC2a and ASIC3 subunits. In addition, we observed that the ASIC2a-dependent surface trafficking of ASIC3 remarkably enhanced the sustained component of the currents. Our study demonstrates that ASIC2a can increase the membrane conductance sensitivity to protons by facilitating the surface expression of ASIC3 through herteromeric assembly. [BMB Reports 2016; 49(10): 542-547] PMID:27241858

  11. Carbonate acidizing

    SciTech Connect

    Daccord, G.; Touboul, E.; Lenormand, R.

    1989-02-01

    The authors present the first quantitative study and complete model of the wormholing phenomenon, leading to a means of predicting and optimizing carbonate acidizing treatments. Laboratory experiments on a gypsum model system and computer simulations show that for a given geometry, wormholes can be quantified by a unique parameter, their equivalent hydraulic length. The behavior of this quantifying parameter vs. all the system parameters is studied and allows the quantitative prediction of the efficiency of an acidizing treatment. This study highlights the fractal nature of the phenomenon, which is accounted for in the equations, and the strong effect of the sample geometry. Three types of etching can be obtained: compact, wormhole type, or homogeneous. The optimum conditions for achieving the best skin decrease correspond to the creation of wormholes and can then be defined in terms of fluid reactivity and injection rate.

  12. Hydroxycarboxylic acids and salts

    DOEpatents

    Kiely, Donald E; Hash, Kirk R; Kramer-Presta, Kylie; Smith, Tyler N

    2015-02-24

    Compositions which inhibit corrosion and alter the physical properties of concrete (admixtures) are prepared from salt mixtures of hydroxycarboxylic acids, carboxylic acids, and nitric acid. The salt mixtures are prepared by neutralizing acid product mixtures from the oxidation of polyols using nitric acid and oxygen as the oxidizing agents. Nitric acid is removed from the hydroxycarboxylic acids by evaporation and diffusion dialysis.

  13. Are the /J/ψ and χc /A dependencies the same?

    NASA Astrophysics Data System (ADS)

    Vogt, R.

    2002-03-01

    It has been empirically observed that the dependence of J/ ψ and ψ' production on nuclear mass number A is very similar. This has been postulated to be due to the predominance of color-octet preresonant states in charmonium production and absorption. Two new experiments, NA60 at CERN and HERA-B at DESY, will measure the χcA dependence for the first time. These measurements should shed new light on the charmonium production and absorption mechanisms.

  14. A-dependent effects in high P{sub T} reactions

    SciTech Connect

    Fields, T.

    1994-08-01

    A brief summary of A-dependent effects which have been observed in various high energy scattering processes from nuclear targets is given. Reactions which are discussed include dijet production, dihadron production, Drell-Yan, deep inelastic muon scattering, and low-P{sub t} hadron production. The data are described in terms of multiple scattering of a fast parton in nuclear matter. Some suggestions for future work are given.

  15. Characterization of Bovine Brain ATPase

    DTIC Science & Technology

    1988-07-01

    process. The oleoyl derivative of lysophosphatidic acid exhibited no inhibition of ATP hydrolysis in contrast to the completely acylated derivative...idyl inosi tol 0 19 Lysophosphatldylinositol 0 2 Phosphatidyl-DL-Glycerol 0 18 Phosphatidic Acid 38 0 Lysophosphatidic Acid , Oleoyl 0 0 32 Tabl e X...for 60% inhibition. We examined the effects of various phospholipids on catalytic activity (Table IX). With the exception of phosphatidic acid , all

  16. Acidic domains around nucleic acids.

    PubMed Central

    Lamm, G; Pack, G R

    1990-01-01

    The hydrogen ion concentration in the vicinity of DNA was mapped out within the Poisson-Boltzmann approximation. Experimental conditions were modeled by assuming Na-DNA to be solvated in a buffer solution containing 45 mM Tris and 3 mM Mg cations at pH 7.5. Three regions of high H+ concentration (greater than 10 microM) are predicted: one throughout the minor groove of DNA and two localized in the major groove near N7 of guanine and C5 of cytosine for a G.C base pair. These acidic domains correlate well with the observed covalent binding sites of benzo[a]pyrene epoxide (N2 of guanine) and of aflatoxin B1 epoxide (N7 of guanine), chemical carcinogens that presumably undergo acid catalysis to form highly reactive carbocations that ultimately bind to DNA. It is suggested that these regions of high H+ concentration may also be of concern in understanding interactions involving proteins and noncarcinogenic molecules with or near nucleic acids. PMID:2123348

  17. Folic Acid and Pregnancy

    MedlinePlus

    ... for TV, Video Games, and the Internet Folic Acid and Pregnancy KidsHealth > For Parents > Folic Acid and ... before conception and during early pregnancy . About Folic Acid Folic acid, sometimes called folate, is a B ...

  18. Methylmalonic acid blood test

    MedlinePlus

    ... acid is a substance produced when proteins, called amino acids, in the body break down. The health care ... Cederbaum S, Berry GT. Inborn errors of carbohydrate, ammonia, amino acid, and organic acid metabolism. In: Gleason CA, Devaskar ...

  19. Understanding Acid Rain

    ERIC Educational Resources Information Center

    Damonte, Kathleen

    2004-01-01

    The term acid rain describes rain, snow, or fog that is more acidic than normal precipitation. To understand what acid rain is, it is first necessary to know what an acid is. Acids can be defined as substances that produce hydrogen ions (H+), when dissolved in water. Scientists indicate how acidic a substance is by a set of numbers called the pH…

  20. New Bioactive Fatty Acids

    USDA-ARS?s Scientific Manuscript database

    Many oxygenated fatty acids are bioactive compounds. Nocardia cholesterolicum and Flavobacterium DS5 convert oleic acid to 10 hydroxy stearic acid and linoleic acid to 10-hydroxy-12(Z)-octadecanoic acid. Pseudomonas aeruginosa PR3 converts oleic acid to new compounds, 7,10-dihydroxy-8(E)-octadecen...

  1. New bioactive fatty acids

    USDA-ARS?s Scientific Manuscript database

    Many oxygenated fatty acids are bioactive compounds. Nocardia cholesterolicum and Flavobacterium DS5 convert oleic acid to 10 hydroxy stearic acid and linoleic acid to 10-hydroxy-12(Z)-octadecanoic acid. Pseudomonas aeruginosa PR3 converts oleic acid to the new compounds, 7,10-dihydroxy-8(E)-octad...

  2. Understanding Acid Rain

    ERIC Educational Resources Information Center

    Damonte, Kathleen

    2004-01-01

    The term acid rain describes rain, snow, or fog that is more acidic than normal precipitation. To understand what acid rain is, it is first necessary to know what an acid is. Acids can be defined as substances that produce hydrogen ions (H+), when dissolved in water. Scientists indicate how acidic a substance is by a set of numbers called the pH…

  3. Acid rain

    SciTech Connect

    Boyle, R.H.; Boyle, R.A.

    1983-01-01

    Acid rain, says Boyle is a chemical leprosy eating into the face of North America and Europe, perhaps the major ecological problem of our time. Boyle describes the causes and scope of the phenomenon; the effects on man, wildlife, water, and our cultural heritage. He probes the delays of politicians and the frequent self-serving arguments advanced by industry in the face of what scientists have proved. The solutions he offers are to strengthen the Clean Air Act and require emission reductions that can be accomplished by establishing emission standards on a regional or bubble basis, burn low-sulfur coal, install scrubbers at critical plants, and invest in alternative energy sources. 73 references, 1 figure.

  4. Acanthoic acid

    PubMed Central

    Suwancharoen, Sunisa; Tommeurd, Wantanee; Phurat, Chuttree; Muangsin, Nongnuj; Pornpakakul, Surachai

    2010-01-01

    The title compound [systematic name: (1R,4aR,7S,8aS,10aS)-1,4a,7-trimethyl-7-vinyl-1,2,3,4,4a,6,7,8,8a,9,10,10a-dodeca­hydro­phenanthrene-1-carb­oxy­lic acid], C20H30O2, is a pimarane-type diterpene extracted from Croton oblongifolius. There are two independent mol­ecules in the asymmetric unit. In both of these, the six-membered rings A, B and C adopt chair, boat and half-chair conformations, respectively. Rings A and B are trans-fused. The two mol­ecules in the asymmetric unit form O—H⋯O hydrogen-bonded R 2 2(8) dimers. The absolute configuration was assigned on the basis of the published literature on analogous structures. PMID:21587780

  5. Pyruvate ferredoxin oxidoreductase from the hyperthermophilic archaeon, Pyrococcus furiosus, functions as a CoA-dependent pyruvate decarboxylase.

    PubMed

    Ma, K; Hutchins, A; Sung, S J; Adams, M W

    1997-09-02

    Pyruvate ferredoxin oxidoreductase (POR) has been previously purified from the hyperthermophilic archaeon, Pyrococcus furiosus, an organism that grows optimally at 100 degrees C by fermenting carbohydrates and peptides. The enzyme contains thiamine pyrophosphate and catalyzes the oxidative decarboxylation of pyruvate to acetyl-CoA and CO2 and reduces P. furiosus ferredoxin. Here we show that this enzyme also catalyzes the formation of acetaldehyde from pyruvate in a CoA-dependent reaction. Desulfocoenzyme A substituted for CoA showing that the cofactor plays a structural rather than a catalytic role. Ferredoxin was not necessary for the pyruvate decarboxylase activity of POR, nor did it inhibit acetaldehyde production. The apparent Km values for CoA and pyruvate were 0.11 mM and 1.1 mM, respectively, and the optimal temperature for acetaldehyde formation was above 90 degrees C. These data are comparable to those previously determined for the pyruvate oxidation reaction of POR. At 80 degrees C (pH 8.0), the apparent Vm value for pyruvate decarboxylation was about 40% of the apparent Vm value for pyruvate oxidation rate (using P. furiosus ferredoxin as the electron acceptor). Tentative catalytic mechanisms for these two reactions are presented. In addition to POR, three other 2-keto acid ferredoxin oxidoreductases are involved in peptide fermentation by hyperthermophilic archaea. It is proposed that the various aldehydes produced by these oxidoreductases in vivo are used by two aldehyde-utilizing enzymes, alcohol dehydrogenase and aldehyde ferredoxin oxidoreductase, the physiological roles of which were previously unknown.

  6. Acid phosphatase and protease activities in immobilized rat skeletal muscles

    NASA Technical Reports Server (NTRS)

    Witzmann, F. A.; Troup, J. P.; Fitts, R. H.

    1982-01-01

    The effect of hind-limb immobilization on selected Iysosomal enzyme activities was studied in rat hing-limb muscles composed primarily of type 1. 2A, or 2B fibers. Following immobilization, acid protease and acid phosphatase both exhibited signifcant increases in their activity per unit weight in all three fiber types. Acid phosphatase activity increased at day 14 of immobilization in the three muscles and returned to control levels by day 21. Acid protease activity also changed biphasically, displaying a higher and earlier rise than acid phosphatase. The pattern of change in acid protease, but not acid phosphatase, closely parallels observed muscle wasting. The present data therefore demonstrate enhanced proteolytic capacity of all three fiber types early during muscular atrophy. In addition, the data suggest a dependence of basal hydrolytic and proteolytic activities and their adaptive response to immobilization on muscle fiber composition.

  7. Acid phosphatase and protease activities in immobilized rat skeletal muscles

    NASA Technical Reports Server (NTRS)

    Witzmann, F. A.; Troup, J. P.; Fitts, R. H.

    1982-01-01

    The effect of hind-limb immobilization on selected Iysosomal enzyme activities was studied in rat hing-limb muscles composed primarily of type 1. 2A, or 2B fibers. Following immobilization, acid protease and acid phosphatase both exhibited signifcant increases in their activity per unit weight in all three fiber types. Acid phosphatase activity increased at day 14 of immobilization in the three muscles and returned to control levels by day 21. Acid protease activity also changed biphasically, displaying a higher and earlier rise than acid phosphatase. The pattern of change in acid protease, but not acid phosphatase, closely parallels observed muscle wasting. The present data therefore demonstrate enhanced proteolytic capacity of all three fiber types early during muscular atrophy. In addition, the data suggest a dependence of basal hydrolytic and proteolytic activities and their adaptive response to immobilization on muscle fiber composition.

  8. The Role of the Co-Chaperone, CHIP, in Androgen Independent Prostate Cancer

    DTIC Science & Technology

    2008-02-01

    expression in LNCap Tsai and LNCap C42 cells. Lysophosphatidic acid (LPA) is an endogenous lipid growth factor that is thought to play important roles...Physiological responses to lysophosphatidic acid and related glycero-phospholipids. Prostaglandins 2001,64:47–62. 9 JK Cheng, T Bawa, P Leey, , et al. Role of...inhibitors of autophagy versus apoptosis. Autophagy is characterized by acidic vesicular organelle (AVO) formation, which is detected and measured by vital

  9. Role of STAT5b in Breast Cancer Progression and Metastasis

    DTIC Science & Technology

    2009-09-01

    cells to these chemokines (Figure 15B) (Muller et al., 2001). We next examined migration to lysophosphatidic acid (LPA), a major component of serum...chambers contained serum-free media (no serum), FBS (serum), charcoal-stripped newborn calf serum (cs-serum), or 2µM lysophosphatidic acid (LPA). 1...are comprised of 6 conserved domains. This figure illustrates the domains of the STAT family member, STAT5b. STAT5b is 787 amino acids in length

  10. Motivation as an independent and a dependent variable in medical education: a review of the literature.

    PubMed

    Kusurkar, R A; Ten Cate, Th J; van Asperen, M; Croiset, G

    2011-01-01

    Motivation in learning behaviour and education is well-researched in general education, but less in medical education. To answer two research questions, 'How has the literature studied motivation as either an independent or dependent variable? How is motivation useful in predicting and understanding processes and outcomes in medical education?' in the light of the Self-determination Theory (SDT) of motivation. A literature search performed using the PubMed, PsycINFO and ERIC databases resulted in 460 articles. The inclusion criteria were empirical research, specific measurement of motivation and qualitative research studies which had well-designed methodology. Only studies related to medical students/school were included. Findings of 56 articles were included in the review. Motivation as an independent variable appears to affect learning and study behaviour, academic performance, choice of medicine and specialty within medicine and intention to continue medical study. Motivation as a dependent variable appears to be affected by age, gender, ethnicity, socioeconomic status, personality, year of medical curriculum and teacher and peer support, all of which cannot be manipulated by medical educators. Motivation is also affected by factors that can be influenced, among which are, autonomy, competence and relatedness, which have been described as the basic psychological needs important for intrinsic motivation according to SDT. Motivation is an independent variable in medical education influencing important outcomes and is also a dependent variable influenced by autonomy, competence and relatedness. This review finds some evidence in support of the validity of SDT in medical education.

  11. RNA G-quadruplexes cause eIF4A-dependent oncogene translation in cancer

    NASA Astrophysics Data System (ADS)

    Wolfe, Andrew L.; Singh, Kamini; Zhong, Yi; Drewe, Philipp; Rajasekhar, Vinagolu K.; Sanghvi, Viraj R.; Mavrakis, Konstantinos J.; Jiang, Man; Roderick, Justine E.; van der Meulen, Joni; Schatz, Jonathan H.; Rodrigo, Christina M.; Zhao, Chunying; Rondou, Pieter; de Stanchina, Elisa; Teruya-Feldstein, Julie; Kelliher, Michelle A.; Speleman, Frank; Porco, John A.; Pelletier, Jerry; Rätsch, Gunnar; Wendel, Hans-Guido

    2014-09-01

    The translational control of oncoprotein expression is implicated in many cancers. Here we report an eIF4A RNA helicase-dependent mechanism of translational control that contributes to oncogenesis and underlies the anticancer effects of silvestrol and related compounds. For example, eIF4A promotes T-cell acute lymphoblastic leukaemia development in vivo and is required for leukaemia maintenance. Accordingly, inhibition of eIF4A with silvestrol has powerful therapeutic effects against murine and human leukaemic cells in vitro and in vivo. We use transcriptome-scale ribosome footprinting to identify the hallmarks of eIF4A-dependent transcripts. These include 5' untranslated region (UTR) sequences such as the 12-nucleotide guanine quartet (CGG)4 motif that can form RNA G-quadruplex structures. Notably, among the most eIF4A-dependent and silvestrol-sensitive transcripts are a number of oncogenes, superenhancer-associated transcription factors, and epigenetic regulators. Hence, the 5' UTRs of select cancer genes harbour a targetable requirement for the eIF4A RNA helicase.

  12. NusA-dependent transcription termination prevents misregulation of global gene expression

    PubMed Central

    Mondal, Smarajit; Yakhnin, Alexander V.; Sebastian, Aswathy; Albert, Istvan; Babitzke, Paul

    2017-01-01

    Intrinsic transcription terminators consist of an RNA hairpin followed by a U-rich tract, and these signals can trigger termination without the involvement of additional factors. Although NusA is known to stimulate intrinsic termination in vitro, the in vivo targets and global impact of NusA are not known because it is essential for viability. Using genome-wide 3′ end-mapping on an engineered Bacillus subtilis NusA depletion strain, we show that weak suboptimal terminators are the principle NusA substrates. Moreover, a subclass of weak non-canonical terminators was identified that completely depend on NusA for effective termination. NusA-dependent terminators tend to have weak hairpins and/or distal U-tract interruptions, supporting a model in which NusA is directly involved in the termination mechanism. Depletion of NusA altered global gene expression directly and indirectly via readthrough of suboptimal terminators. Readthrough of NusA-dependent terminators caused misregulation of genes involved in essential cellular functions, especially DNA replication and metabolism. We further show that nusA is autoregulated by a transcription attenuation mechanism that does not rely on antiterminator structures. Instead, NusA-stimulated termination in its 5′ UTR dictates the extent of transcription into the operon, thereby ensuring tight control of cellular NusA levels. PMID:27571753

  13. PUMA promotes Bax translocation in FOXO3a-dependent pathway during STS-induced apoptosis

    NASA Astrophysics Data System (ADS)

    Zhang, Yingjie; Chen, Qun

    2009-08-01

    PUMA (p53 up-regulated modulator of apoptosis, also called Bbc3) was first identified as a BH3-only Bcl-2 family protein that is transcriptionally up-regulated by p53 and activated upon p53-dependent apoptotic stimuli, such as treatment with DNA-damaging drugs or UV irradiation. Recently studies have been shown that Puma is also up-regulated in response to certain p53-independent apoptotic stimuli, such as growth factor deprivation or treatment with glucocorticoids or STS (staurosporine). However, the molecular mechanisms of PUMA up-regulation and how PUMA functions in response to p53-independent apoptotic stimuli remain poorly understood. In this study, based on real-time single cell analysis, flow cytometry and western blotting technique, we investigated the function of PUMA in living human lung adenocarcinoma cells (ASTC-a-1) after STS treatment. Our results show that FOXO3a was activated by STS stimulation and then translocated from cytosol to nucleus. The expression of PUMA was up-regulated via a FOXO3a-dependent manner after STS treatment, while p53 had little function in this process. Moreover, cell apoptosis and Bax translocation induced by STS were not blocked by Pifithrin-α (p53 inhibitor), which suggested that p53 was not involved in this signaling pathway. Taken together, these results indicate that PUMA promoted Bax translocation in a FOXO3a-dependment pathway during STS-induced apoptosis, while p53 was dispensable in this process.

  14. Acid rain

    SciTech Connect

    Gay, K.

    1983-01-01

    Deposition of acidic substances from the atmosphere is considered by many to be, along with increasing CO/sub 2/ concentrations in the atmosphere, one of the most serious environmental problems of this generation. Despite the limited title of this small book, it touches, in a nontechnical and elementary way, on all of the important aspects of this subject: definitions, history, suspected causes and harmful effects, proposed remedial actions, the case for additional research, and political and economic impacts. The material is presented largely as statements and opinions of scientists and governmental officials. The book is reportorial in style and reasonably balanced in its presentation of contrasting and opposing opinions about causes, effects, and remedies, although the final chapter, What Citizens Can Do, includes the names and addresses of organizations involved in efforts to protect clean air, forestry and wilderness areas. Also included are school projects and examples of what individuals and groups have done to help us understand the problem and/or to promote action.

  15. A-dependence of the Spectra of the F Isotopes from ab initio Calculations

    NASA Astrophysics Data System (ADS)

    Barrett, Bruce R.; Dikmen, Erdal; Maris, Pieter; Vary, James P.; Shirokov, Andrey M.

    2016-03-01

    Using a succession of Okubo-Lee-Suzuki transformations within the No Core Shell Model (NCSM) formalism, we derive an ab initio, non-perturbative procedure for calculating the input for standard shell-model (SSM) calculations within one major shell. We have used this approach for calculating the spectra of the F isotopes from A=18 to A=25, so as to study the A-dependence of the results. In particular, we are interested in seeing if the theoretical input is weak enough, so that a single set of two-body effective interactions can be used for all of the F isotopes investigated. We will present results from SSM calculations based on input obtained with the JISP16 nucleon-nucleon interaction in an initial 4 ℏΩ NCSM basis space. This work supported in part by TUBITAK-BIDEB, the US DOE, the US NSF, NERSC, and the Russian Ministry of Education and Science.

  16. Continuously rethinking the definition of influenza for surveillance systems: a Dependent Bayesian Expert System.

    PubMed

    Alemi, Farrokh; Atherton, Martin J; Pattie, David C; Torii, Manabu

    2013-08-01

    In the Electronic Surveillance System for the Early Notification of Community-based Epidemics (ESSENCE), influenza was originally defined by a list of 29 and later by a list of 12 diagnosis codes. This article describes a dependent Bayesian procedure designed to improve the ESSENCE system and exploit multiple sources of information without being biased by redundancy. We obtained 13,096 cases within the Armed Forces Health Longitudinal Technological Application electronic medical records that included an influenza laboratory test. A Dependent Bayesian Expert System (D-BESt) was used to predict influenza from diagnoses, symptoms, reason for visit, temperature, month of visit, category of enrollment, and demographics. For each case, D-BESt sequentially selects the most discriminating piece of information, calculates its likelihood ratio conditioned on previously selected information, and updates the case's probability of influenza. When the analysis was limited to definitions based on diagnoses and was applied to a sample of patients for whom laboratory tests had been ordered, the areas under the receiver operating characteristic curve (AUCs) for the previous (29-diagnosis) and current (12-diagnosis) ESSENCE lists and the D-BESt algorithm were, respectively, 0.47, 0.36, and 0.77. Including other sources of information further improved the AUC for D-BESt to 0.79. At the best cutoff point for D-BESt, where the receiver operating characteristic curve for D-BESt is farthest from the diagonal line, the D-BESt algorithm correctly classified 84% of cases (specificity = 88%, sensitivity = 62%). In comparison, the current ESSENCE approach of using a list of 12 diagnoses correctly classified only 31% of this sample of cases (specificity = 29%, sensitivity = 42%). False alarms in ESSENCE surveillance systems can be reduced if a probabilistic dynamic learning system is used.

  17. Creating Directed Double-strand Breaks with the Ref Protein: A Novel Rec A-Dependent Nuclease from Bacteriophage P1

    SciTech Connect

    Gruenig, Marielle C.; Lu, Duo; Won, Sang Joon; Dulberger, Charles L.; Manlick, Angela J.; Keck, James L.; Cox, Michael M.

    2012-03-16

    The bacteriophage P1-encoded Ref protein enhances RecA-dependent recombination in vivo by an unknown mechanism. We demonstrate that Ref is a new type of enzyme; that is, a RecA-dependent nuclease. Ref binds to ss- and dsDNA but does not cleave any DNA substrate until RecA protein and ATP are added to form RecA nucleoprotein filaments. Ref cleaves only where RecA protein is bound. RecA functions as a co-nuclease in the Ref/RecA system. Ref nuclease activity can be limited to the targeted strands of short RecA-containing D-loops. The result is a uniquely programmable endonuclease activity, producing targeted double-strand breaks at any chosen DNA sequence in an oligonucleotide-directed fashion. We present evidence indicating that cleavage occurs in the RecA filament groove. The structure of the Ref protein has been determined to 1.4 {angstrom} resolution. The core structure, consisting of residues 77-186, consists of a central 2-stranded {beta}-hairpin that is sandwiched between several {alpha}-helical and extended loop elements. The N-terminal 76 amino acid residues are disordered; this flexible region is required for optimal activity. The overall structure of Ref, including several putative active site histidine residues, defines a new subclass of HNH-family nucleases. We propose that enhancement of recombination by Ref reflects the introduction of directed, recombinogenic double-strand breaks.

  18. Effect of Exposure to Atmospheric Ultrafine Particles on Production of Free Fatty Acids and Lipid Metabolites in the Mouse Small Intestine

    PubMed Central

    Li, Rongsong; Navab, Kaveh; Hough, Greg; Daher, Nancy; Zhang, Min; Mittelstein, David; Lee, Katherine; Pakbin, Payam; Saffari, Arian; Bhetraratana, May; Sulaiman, Dawoud; Beebe, Tyler; Wu, Lan; Jen, Nelson; Wine, Eytan; Tseng, Chi-Hong; Araujo, Jesus A.; Fogelman, Alan; Sioutas, Constantinos; Navab, Mohamed

    2014-01-01

    Background: Exposure to ambient ultrafine particulate matter (UFP) is a well-recognized risk factor for cardiovascular and respiratory diseases. However, little is known about the effects of air pollution on gastrointestinal disorders. Objective: We sought to assess whether exposure to ambient UFP (diameter < 180 nm) increased free fatty acids and lipid metabolites in the mouse small intestine. Methods: Ldlr-null mice were exposed to filtered air (FA) or UFP collected at an urban Los Angeles, California, site that was heavily affected by vehicular emissions; the exposure was carried out for 10 weeks in the presence or absence of D-4F, an apolipoprotein A-I mimetic peptide with antioxidant and anti-inflammation properties on a high-fat or normal chow diet. Results: Compared with FA, exposure to UFP significantly increased intestinal hydroxyeicosatetraenoic acids (HETEs), including 15-HETE, 12-HETE, 5-HETE, as well as hydroxyoctadecadienoic acids (HODEs), including 13-HODE and 9-HODE. Arachidonic acid (AA) and prostaglandin D2 (PGD2) as well as some of the lysophosphatidic acids (LPA) in the small intestine were also increased in response to UFP exposure. Administration of D-4F significantly reduced UFP-mediated increase in HETEs, HODEs, AA, PGD2, and LPA. Although exposure to UFP further led to shortened villus length accompanied by prominent macrophage and neutrophil infiltration into the intestinal villi, administration of D-4F mitigated macrophage infiltration. Conclusions: Exposure to UFP promotes lipid metabolism, villus shortening, and inflammatory responses in mouse small intestine, whereas administration of D-4F attenuated these effects. Our findings provide a basis to further assess the mechanisms underlying UFP-mediated lipid metabolism in the digestive system with clinical relevance to gut homeostasis and diseases. Citation: Li R, Navab K, Hough G, Daher N, Zhang M, Mittelstein D, Lee K, Pakbin P, Saffari A, Bhetraratana M, Sulaiman D, Beebe T, Wu L, Jen

  19. [Teichoic acids from lactic acid bacteria].

    PubMed

    Livins'ka, O P; Harmasheva, I L; Kovalenko, N K

    2012-01-01

    The current view of the structural diversity of teichoic acids and their involvement in the biological activity of lactobacilli has been reviewed. The mechanisms of effects of probiotic lactic acid bacteria, in particular adhesive and immunostimulating functions have been described. The prospects of the use of structure data of teichoic acid in the assessment of intraspecific diversity of lactic acid bacteria have been also reflected.

  20. Organic acids tunably catalyze carbonic acid decomposition.

    PubMed

    Kumar, Manoj; Busch, Daryle H; Subramaniam, Bala; Thompson, Ward H

    2014-07-10

    Density functional theory calculations predict that the gas-phase decomposition of carbonic acid, a high-energy, 1,3-hydrogen atom transfer reaction, can be catalyzed by a monocarboxylic acid or a dicarboxylic acid, including carbonic acid itself. Carboxylic acids are found to be more effective catalysts than water. Among the carboxylic acids, the monocarboxylic acids outperform the dicarboxylic ones wherein the presence of an intramolecular hydrogen bond hampers the hydrogen transfer. Further, the calculations reveal a direct correlation between the catalytic activity of a monocarboxylic acid and its pKa, in contrast to prior assumptions about carboxylic-acid-catalyzed hydrogen-transfer reactions. The catalytic efficacy of a dicarboxylic acid, on the other hand, is significantly affected by the strength of an intramolecular hydrogen bond. Transition-state theory estimates indicate that effective rate constants for the acid-catalyzed decomposition are four orders-of-magnitude larger than those for the water-catalyzed reaction. These results offer new insights into the determinants of general acid catalysis with potentially broad implications.

  1. Uric acid test (image)

    MedlinePlus

    Uric acid urine test is performed to check for the amount of uric acid in urine. Urine is collected over a 24 ... testing. The most common reason for measuring uric acid levels is in the diagnosis or treatment of ...

  2. Fatty Acid Oxidation Disorders

    MedlinePlus

    ... other health conditions > Fatty acid oxidation disorders Fatty acid oxidation disorders E-mail to a friend Please ... these disorders, go to genetests.org . What fatty acid oxidation disorders are tested for in newborn screening? ...

  3. Facts about Folic Acid

    MedlinePlus

    ... Information For… Media Policy Makers Facts About Folic Acid Language: English (US) Español (Spanish) Recommend on ... of the baby’s brain and spine. About folic acid Folic acid is a B vitamin. Our bodies ...

  4. Uric acid - urine

    MedlinePlus

    ... page: //medlineplus.gov/ency/article/003616.htm Uric acid urine test To use the sharing features on this page, please enable JavaScript. The uric acid urine test measures the level of uric acid ...

  5. Regulation of 2-5A Dependent RNase at the Level of its Phosphorylation

    DTIC Science & Technology

    1991-06-26

    extract as follows: 25 ul wheat germ extract 10 ul H2O 1 ul RNasin ribonuclease inhibitor (40 u/ml) 7 ul ImM amino acid mixture 1 ul IM... wheat germ extract . A cDNA clone coding for 2-5A-depRNase was isolated (B. Hassel, A. Zhou, and R.H. Silverman, unpublished), in vitro transcribed...and the corresponding mRNA was in vitro translated in cell free extracts of wheat germ . In vitro transcription. Incubations were set up in 0.5 ml

  6. Acid distribution in phosphoric acid fuel cells

    SciTech Connect

    Okae, I.; Seya, A.; Umemoto, M.

    1996-12-31

    Electrolyte acid distribution among each component of a cell is determined by capillary force when the cell is not in operation, but the distribution under the current load conditions had not been clear so far. Since the loss of electrolyte acid during operation is inevitable, it is necessary to store enough amount of acid in every cell. But it must be under the level of which the acid disturbs the diffusion of reactive gases. Accordingly to know the actual acid distribution during operation in a cell is very important. In this report, we carried out experiments to clarify the distribution using small single cells.

  7. Nuclear Envelope Protein SUN2 Promotes Cyclophilin-A-Dependent Steps of HIV Replication

    PubMed Central

    Lahaye, Xavier; Satoh, Takeshi; Gentili, Matteo; Cerboni, Silvia; Silvin, Aymeric; Conrad, Cécile; Ahmed-Belkacem, Abdelhakim; Rodriguez, Elisa C.; Guichou, Jean-François; Bosquet, Nathalie; Piel, Matthieu; Le Grand, Roger; King, Megan C.; Pawlotsky, Jean-Michel; Manel, Nicolas

    2016-01-01

    Summary During the early phase of replication, HIV reverse transcribes its RNA and crosses the nuclear envelope while escaping host antiviral defenses. The host factor Cyclophilin A (CypA) is essential for these steps and binds the HIV capsid; however, the mechanism underlying this effect remains elusive. Here, we identify related capsid mutants in HIV-1, HIV-2, and SIVmac that are restricted by CypA. This antiviral restriction of mutated viruses is conserved across species and prevents nuclear import of the viral cDNA. Importantly, the inner nuclear envelope protein SUN2 is required for the antiviral activity of CypA. We show that wild-type HIV exploits SUN2 in primary CD4+ T cells as an essential host factor that is required for the positive effects of CypA on reverse transcription and infection. Altogether, these results establish essential CypA-dependent functions of SUN2 in HIV infection at the nuclear envelope. PMID:27149839

  8. Two-stage estimation for multivariate recurrent event data with a dependent terminal event.

    PubMed

    Chen, Chyong-Mei; Chuang, Ya-Wen; Shen, Pao-Sheng

    2015-03-01

    Recurrent event data arise in longitudinal follow-up studies, where each subject may experience the same type of events repeatedly. The work in this article is motivated by the data from a study of repeated peritonitis for patients on peritoneal dialysis. Due to the aspects of medicine and cost, the peritonitis cases were classified into two types: Gram-positive and non-Gram-positive peritonitis. Further, since the death and hemodialysis therapy preclude the occurrence of recurrent events, we face multivariate recurrent event data with a dependent terminal event. We propose a flexible marginal model, which has three characteristics: first, we assume marginal proportional hazard and proportional rates models for terminal event time and recurrent event processes, respectively; second, the inter-recurrences dependence and the correlation between the multivariate recurrent event processes and terminal event time are modeled through three multiplicative frailties corresponding to the specified marginal models; third, the rate model with frailties for recurrent events is specified only on the time before the terminal event. We propose a two-stage estimation procedure for estimating unknown parameters. We also establish the consistency of the two-stage estimator. Simulation studies show that the proposed approach is appropriate for practical use. The methodology is applied to the peritonitis cohort data that motivated this study.

  9. E1A dependent up-regulation of c-jun/AP-1 activity.

    PubMed Central

    Kitabayashi, I; Chiu, R; Gachelin, G; Yokoyama, K

    1991-01-01

    E1A, the early region 1A transcription unit of human adenovirus, exhibits multiple functions that regulate the expression of some cellular genes and promote cell growth and division. We found that E1A stimulated c-jun gene expression at least fifty-fold in rat 3Y1 cells in a serum-independent manner, concomitantly with E1A down-regulation of jun B expression. The E1A-dependent induction of c-jun transcription resulted in increase amount of cJun/AP1. This induction was mediated by the enhancement of the binding activity of the transcription factor cJun/AP1 to an AP1 binding site in the c-jun promoter. Additionally, this induction can be repressed by introducing junB into the cells. Taken collectively, these results suggest that the differential expression of two closely related proteins greatly expands their cellular regulation. Induction of c-jun expression by E1A as well as c-jun autoregulation may amplify the action of E1A during adenovirus infection. Therefore, some of the biological effects of E1A may include mediating the constitutive activation of c-jun, which is important in transcriptional regulation and oncogenic transformation. Images PMID:1826351

  10. Selective amputation of the pharynx identifies a FoxA-dependent regeneration program in planaria.

    PubMed

    Adler, Carolyn E; Seidel, Chris W; McKinney, Sean A; Sánchez Alvarado, Alejandro

    2014-04-15

    Planarian flatworms regenerate every organ after amputation. Adult pluripotent stem cells drive this ability, but how injury activates and directs stem cells into the appropriate lineages is unclear. Here we describe a single-organ regeneration assay in which ejection of the planarian pharynx is selectively induced by brief exposure of animals to sodium azide. To identify genes required for pharynx regeneration, we performed an RNAi screen of 356 genes upregulated after amputation, using successful feeding as a proxy for regeneration. We found that knockdown of 20 genes caused a wide range of regeneration phenotypes and that RNAi of the forkhead transcription factor FoxA, which is expressed in a subpopulation of stem cells, specifically inhibited regrowth of the pharynx. Selective amputation of the pharynx therefore permits the identification of genes required for organ-specific regeneration and suggests an ancient function for FoxA-dependent transcriptional programs in driving regeneration. DOI: http://dx.doi.org/10.7554/eLife.02238.001.

  11. Selective amputation of the pharynx identifies a FoxA-dependent regeneration program in planaria

    PubMed Central

    Adler, Carolyn E; Seidel, Chris W; McKinney, Sean A; Sánchez Alvarado, Alejandro

    2014-01-01

    Planarian flatworms regenerate every organ after amputation. Adult pluripotent stem cells drive this ability, but how injury activates and directs stem cells into the appropriate lineages is unclear. Here we describe a single-organ regeneration assay in which ejection of the planarian pharynx is selectively induced by brief exposure of animals to sodium azide. To identify genes required for pharynx regeneration, we performed an RNAi screen of 356 genes upregulated after amputation, using successful feeding as a proxy for regeneration. We found that knockdown of 20 genes caused a wide range of regeneration phenotypes and that RNAi of the forkhead transcription factor FoxA, which is expressed in a subpopulation of stem cells, specifically inhibited regrowth of the pharynx. Selective amputation of the pharynx therefore permits the identification of genes required for organ-specific regeneration and suggests an ancient function for FoxA-dependent transcriptional programs in driving regeneration. DOI: http://dx.doi.org/10.7554/eLife.02238.001 PMID:24737865

  12. Aurora-A-Dependent Control of TACC3 Influences the Rate of Mitotic Spindle Assembly

    PubMed Central

    Joseph, Nimesh; Cavazza, Tommaso; Vernos, Isabelle; Pfuhl, Mark; Gergely, Fanni; Bayliss, Richard

    2015-01-01

    The essential mammalian gene TACC3 is frequently mutated and amplified in cancers and its fusion products exhibit oncogenic activity in glioblastomas. TACC3 functions in mitotic spindle assembly and chromosome segregation. In particular, phosphorylation on S558 by the mitotic kinase, Aurora-A, promotes spindle recruitment of TACC3 and triggers the formation of a complex with ch-TOG-clathrin that crosslinks and stabilises kinetochore microtubules. Here we map the Aurora-A-binding interface in TACC3 and show that TACC3 potently activates Aurora-A through a domain centered on F525. Vertebrate cells carrying homozygous F525A mutation in the endogenous TACC3 loci exhibit defects in TACC3 function, namely perturbed localization, reduced phosphorylation and weakened interaction with clathrin. The most striking feature of the F525A cells however is a marked shortening of mitosis, at least in part due to rapid spindle assembly. F525A cells do not exhibit chromosome missegregation, indicating that they undergo fast yet apparently faithful mitosis. By contrast, mutating the phosphorylation site S558 to alanine in TACC3 causes aneuploidy without a significant change in mitotic duration. Our work has therefore defined a regulatory role for the Aurora-A-TACC3 interaction beyond the act of phosphorylation at S558. We propose that the regulatory relationship between Aurora-A and TACC3 enables the transition from the microtubule-polymerase activity of TACC3-ch-TOG to the microtubule-crosslinking activity of TACC3-ch-TOG-clathrin complexes as mitosis progresses. Aurora-A-dependent control of TACC3 could determine the balance between these activities, thereby influencing not only spindle length and stability but also the speed of spindle formation with vital consequences for chromosome alignment and segregation. PMID:26134678

  13. Helicobacter pylori inhibits the cleavage of TRAF1 via a CagA-dependent mechanism.

    PubMed

    Wan, Xiu-Kun; Yuan, Sheng-Ling; Wang, Yan-Chun; Tao, Hao-Xia; Jiang, Wei; Guan, Zhang-Yan; Cao, Cheng; Liu, Chun-Jie

    2016-12-28

    To study the impact on cleavage of tumor necrosis factor receptor-associated factor 1 (TRAF1) regulated by Helicobacter pylori (H. pylori). Cleavage of TRAF1 was detected by western blotting in the human gastric cancer cell line AGS following treatment with an apoptosis inducer. Cleavage of TRAF1 mediated by caspase was examined in vitro using specific caspase inhibitors. The effect of the COOH-terminal TRAF1 fragment on gastric cell apoptosis during H. pylori infection was measured using flow cytometry. The impact of H. pylori infection on TRAF1 cleavage was detected in the presence of apoptosis inducer. The roles of H. pylori virulence factors that may regulate TRAF1 cleavage were analyzed using isogenic cagA-, vacA- and cagE-null mutants. TRAF1 was found to be cleaved in AGS cells treated with the apoptosis inducer, and caspase-8 was the major caspase involved in the cleavage of TRAF1. The COOH-terminal TRAF1 fragment significantly induced cell apoptosis (P < 0.05) as well as promoted H. pylori-induced cell apoptosis (P < 0.05). H. pylori infection was found to significantly inhibit the cleavage of TRAF1 and to inhibit the activation of caspase-8 in the presence of the apoptosis inducer at specific infection times and different cell/bacteria ratios. We also found that the effects of cagE- and cagA-null mutants on the inhibition of TRAF1 cleavage and activation of caspase-8 were significantly attenuated, compared with wild-type H. pylori, in the presence of the apoptosis inducer, showing that the virulence factor CagA was mainly involved in the inhibition of TRAF1 cleavage. H. pylori infection significantly inhibits the cleavage of TRAF1 via a CagA-dependent mechanism, which would increase the relative amounts of full-length TRAF1 and exert an antiapoptotic effect on H. pylori-infected cells.

  14. The DnaE polymerase from Deinococcus radiodurans features RecA-dependent DNA polymerase activity

    PubMed Central

    Randi, Lorenzo; Perrone, Alessandro; Maturi, Mirko; Dal Piaz, Fabrizio; Camerani, Michela; Hochkoeppler, Alejandro

    2016-01-01

    We report in the present study on the catalytic properties of the Deinococcus radiodurans DNA polymerase III α subunit (αDr). The αDr enzyme was overexpressed in Escherichia coli, both in soluble form and as inclusion bodies. When purified from soluble protein extracts, αDr was found to be tightly associated with E. coli RNA polymerase, from which αDr could not be dissociated. On the contrary, when refolded from inclusion bodies, αDr was devoid of E. coli RNA polymerase and was purified to homogeneity. When assayed with different DNA substrates, αDr featured slower DNA extension rates when compared with the corresponding enzyme from E. coli (E. coli DNA Pol III, αEc), unless under high ionic strength conditions or in the presence of manganese. Further assays were performed using a ssDNA and a dsDNA, whose recombination yields a DNA substrate. Surprisingly, αDr was found to be incapable of recombination-dependent DNA polymerase activity, whereas αEc was competent in this action. However, in the presence of the RecA recombinase, αDr was able to efficiently extend the DNA substrate produced by recombination. Upon comparing the rates of RecA-dependent and RecA-independent DNA polymerase activities, we detected a significant activation of αDr by the recombinase. Conversely, the activity of αEc was found maximal under non-recombination conditions. Overall, our observations indicate a sharp contrast between the catalytic actions of αDr and αEc, with αDr more performing under recombination conditions, and αEc preferring DNA substrates whose extension does not require recombination events. PMID:27789781

  15. Determinants of acid secretion.

    PubMed

    Khanna, M U; Abraham, P

    1990-09-01

    Acid secretion is regulated by hormonal factors acting peripherally and centrally, as well as neural factors. Gastrin and histamine are the two most important peripheral hormonal stimulants, while the vagus is the predominant nerve affecting acid secretion. Meal related acid secretion occurs in three phases: cephalic, gastric and intestinal. Acid secretion is stimulated in the first two phases while it is inhibited in the intestinal phase. Proteins are potent acid stimulants but carbohydrates and fats are inhibitors. Tea, coffee, milk and alcohol are acid stimulants; on the other hand the damaging influence of spices on the stomach may not be related to increased acid secretion. Psychological stress has a variable effect. The effect of Helicobacter pylori infection on acid secretion is being elucidated. Many drugs modifying acid secretion are available and are useful in the treatment of acid peptic disease.

  16. Acid tolerance in amphibians

    SciTech Connect

    Pierce, B.A.

    1985-04-01

    Studies of amphibian acid tolerance provide information about the potential effects of acid deposition on amphibian communities. Amphibians as a group appear to be relatively acid tolerant, with many species suffering increased mortality only below pH 4. However, amphibians exhibit much intraspecific variation in acid tolerance, and some species are sensitive to even low levels of acidity. Furthermore, nonlethal effects, including depression of growth rates and increases in developmental abnormalities, can occur at higher pH.

  17. Gas-phase acidities of aspartic acid, glutamic acid, and their amino acid amides

    NASA Astrophysics Data System (ADS)

    Li, Zhong; Matus, Myrna H.; Velazquez, Hector Adam; Dixon, David A.; Cassady, Carolyn J.

    2007-09-01

    Gas-phase acidities (GA or [Delta]Gacid) for the two most acidic common amino acids, aspartic acid and glutamic acid, have been determined for the first time. Because of the amide linkage's importance in peptides and as an aid in studying side chain versus main chain deprotonation, aspartic acid amide and glutamic acid amide were also studied. Experimental GA values were measured by proton transfer reactions in an electrospray ionization/Fourier transform ion cyclotron resonance mass spectrometer. Calculated GAs were obtained by density functional and molecular orbital theory approaches. The best agreement with experiment was found at the G3MP2 level; the MP2/CBS and B3LYP/aug-cc-pVDZ results are 3-4 kcal/mol more acidic than the G3MP2 results. Experiment shows that aspartic acid is more acidic than glutamic acid by ca. 3 kcal/mol whereas the G3MP2 results show a smaller acidity difference of 0.2 kcal/mol. Similarly, aspartic acid amide is experimentally observed to be ca. 2 kcal/mol more acidic than glutamic acid amide whereas the G3MP2 results show a correspondingly smaller energy difference of 0.7 kcal/mol. The computational results clearly show that the anions are all ring-like structures with strong hydrogen bonds between the OH or NH2 groups and the CO2- group from which the proton is removed. The two amino acids are main-chain deprotonated. In addition, use of the COSMO model for the prediction of the free energy differences in aqueous solution gave values in excellent agreement with the most recent experimental values for pKa. Glutamic acid is predicted to be more acidic than aspartic acid in aqueous solution due to differential solvation effects.

  18. Lipid phosphate phosphohydrolase-1 degrades exogenous glycerolipid and sphingolipid phosphate esters.

    PubMed Central

    Jasinska, R; Zhang, Q X; Pilquil, C; Singh, I; Xu, J; Dewald, J; Dillon, D A; Berthiaume, L G; Carman, G M; Waggoner, D W; Brindley, D N

    1999-01-01

    Lipid phosphate phosphohydrolase (LPP)-1 cDNA was cloned from a rat liver cDNA library. It codes for a 32-kDa protein that shares 87 and 82% amino acid sequence identities with putative products of murine and human LPP-1 cDNAs, respectively. Membrane fractions of rat2 fibroblasts that stably expressed mouse or rat LPP-1 exhibited 3.1-3. 6-fold higher specific activities for phosphatidate dephosphorylation compared with vector controls. Increases in the dephosphorylation of lysophosphatidate, ceramide 1-phosphate, sphingosine 1-phosphate and diacylglycerol pyrophosphate were similar to those for phosphatidate. Rat2 fibroblasts expressing mouse LPP-1 cDNA showed 1.6-2.3-fold increases in the hydrolysis of exogenous lysophosphatidate, phosphatidate and ceramide 1-phosphate compared with vector control cells. Recombinant LPP-1 was located partially in plasma membranes with its C-terminus on the cytosolic surface. Lysophosphatidate dephosphorylation was inhibited by extracellular Ca2+ and this inhibition was diminished by extracellular Mg2+. Changing intracellular Ca2+ concentrations did not alter exogenous lysophosphatidate dephosphorylation significantly. Permeabilized fibroblasts showed relatively little latency for the dephosphorylation of exogenous lysophosphatidate. LPP-1 expression decreased the activation of mitogen-activated protein kinase and DNA synthesis by exogenous lysophosphatidate. The product of LPP-1 cDNA is concluded to act partly to degrade exogenous lysophosphatidate and thereby regulate its effects on cell signalling. PMID:10359651

  19. Lipid phosphate phosphohydrolase-1 degrades exogenous glycerolipid and sphingolipid phosphate esters.

    PubMed

    Jasinska, R; Zhang, Q X; Pilquil, C; Singh, I; Xu, J; Dewald, J; Dillon, D A; Berthiaume, L G; Carman, G M; Waggoner, D W; Brindley, D N

    1999-06-15

    Lipid phosphate phosphohydrolase (LPP)-1 cDNA was cloned from a rat liver cDNA library. It codes for a 32-kDa protein that shares 87 and 82% amino acid sequence identities with putative products of murine and human LPP-1 cDNAs, respectively. Membrane fractions of rat2 fibroblasts that stably expressed mouse or rat LPP-1 exhibited 3.1-3. 6-fold higher specific activities for phosphatidate dephosphorylation compared with vector controls. Increases in the dephosphorylation of lysophosphatidate, ceramide 1-phosphate, sphingosine 1-phosphate and diacylglycerol pyrophosphate were similar to those for phosphatidate. Rat2 fibroblasts expressing mouse LPP-1 cDNA showed 1.6-2.3-fold increases in the hydrolysis of exogenous lysophosphatidate, phosphatidate and ceramide 1-phosphate compared with vector control cells. Recombinant LPP-1 was located partially in plasma membranes with its C-terminus on the cytosolic surface. Lysophosphatidate dephosphorylation was inhibited by extracellular Ca2+ and this inhibition was diminished by extracellular Mg2+. Changing intracellular Ca2+ concentrations did not alter exogenous lysophosphatidate dephosphorylation significantly. Permeabilized fibroblasts showed relatively little latency for the dephosphorylation of exogenous lysophosphatidate. LPP-1 expression decreased the activation of mitogen-activated protein kinase and DNA synthesis by exogenous lysophosphatidate. The product of LPP-1 cDNA is concluded to act partly to degrade exogenous lysophosphatidate and thereby regulate its effects on cell signalling.

  20. Helicobacter pylori inhibits the cleavage of TRAF1 via a CagA-dependent mechanism

    PubMed Central

    Wan, Xiu-Kun; Yuan, Sheng-Ling; Wang, Yan-Chun; Tao, Hao-Xia; Jiang, Wei; Guan, Zhang-Yan; Cao, Cheng; Liu, Chun-Jie

    2016-01-01

    AIM To study the impact on cleavage of tumor necrosis factor receptor-associated factor 1 (TRAF1) regulated by Helicobacter pylori (H. pylori). METHODS Cleavage of TRAF1 was detected by western blotting in the human gastric cancer cell line AGS following treatment with an apoptosis inducer. Cleavage of TRAF1 mediated by caspase was examined in vitro using specific caspase inhibitors. The effect of the COOH-terminal TRAF1 fragment on gastric cell apoptosis during H. pylori infection was measured using flow cytometry. The impact of H. pylori infection on TRAF1 cleavage was detected in the presence of apoptosis inducer. The roles of H. pylori virulence factors that may regulate TRAF1 cleavage were analyzed using isogenic cagA-, vacA- and cagE-null mutants. RESULTS TRAF1 was found to be cleaved in AGS cells treated with the apoptosis inducer, and caspase-8 was the major caspase involved in the cleavage of TRAF1. The COOH-terminal TRAF1 fragment significantly induced cell apoptosis (P < 0.05) as well as promoted H. pylori-induced cell apoptosis (P < 0.05). H. pylori infection was found to significantly inhibit the cleavage of TRAF1 and to inhibit the activation of caspase-8 in the presence of the apoptosis inducer at specific infection times and different cell/bacteria ratios. We also found that the effects of cagE- and cagA-null mutants on the inhibition of TRAF1 cleavage and activation of caspase-8 were significantly attenuated, compared with wild-type H. pylori, in the presence of the apoptosis inducer, showing that the virulence factor CagA was mainly involved in the inhibition of TRAF1 cleavage. CONCLUSION H. pylori infection significantly inhibits the cleavage of TRAF1 via a CagA-dependent mechanism, which would increase the relative amounts of full-length TRAF1 and exert an antiapoptotic effect on H. pylori-infected cells. PMID:28082808

  1. Identification and characterization of AckA-dependent protein acetylation in Neisseria gonorrhoeae

    PubMed Central

    Post, Deborah M. B.; Schilling, Birgit; Reinders, Lorri M.; D’Souza, Alexandria K.; Ketterer, Margaret R.; Kiel, Steven J.; Chande, Aroon T.; Apicella, Michael A.; Gibson, Bradford W.

    2017-01-01

    Neisseria gonorrhoeae, the causative agent of gonorrhea, has a number of factors known to contribute to pathogenesis; however, a full understanding of these processes and their regulation has proven to be elusive. Post-translational modifications (PTMs) of bacterial proteins are now recognized as one mechanism of protein regulation. In the present study, Western blot analyses, with an anti-acetyl-lysine antibody, indicated that a large number of gonococcal proteins are post-translationally modified. Previous work has shown that Nε-lysine acetylation can occur non-enzymatically with acetyl-phosphate (AcP) as the acetyl donor. In the current study, an acetate kinase mutant (1291ackA), which accumulates AcP, was generated in N. gonorrhoeae. Broth cultures of N. gonorrhoeae 1291wt and 1291ackA were grown, proteins extracted and digested, and peptides containing acetylated-lysines (K-acetyl) were affinity-enriched from both strains. Mass spectrometric analyses of these samples identified a total of 2686 unique acetylation sites. Label-free relative quantitation of the K-acetyl peptides derived from the ackA and wild-type (wt) strains demonstrated that 109 acetylation sites had an ackA/wt ratio>2 and p-values <0.05 in at least 2/3 of the biological replicates and were designated as “AckA-dependent”. Regulated K-acetyl sites were found in ribosomal proteins, central metabolism proteins, iron acquisition and regulation proteins, pilus assembly and regulation proteins, and a two-component response regulator. Since AckA is part of a metabolic pathway, comparative growth studies of the ackA mutant and wt strains were performed. The mutant showed a growth defect under aerobic conditions, an inability to grow anaerobically, and a defect in biofilm maturation. In conclusion, the current study identified AckA-dependent acetylation sites in N. gonorrhoeae and determined that these sites are found in a diverse group of proteins. This work lays the foundation for future studies

  2. Toxicity of adipic acid.

    PubMed

    Kennedy, Gerald L

    2002-05-01

    Adipic acid has very low acute toxicity in rats with an LD50 > 5000 mg/kg. Adipic acid produced mild to no skin irritation on intact guinea pig skin as a 50% concentration in propylene glycol; it was not a skin sensitizer. Adipic acid caused mild conjunctival irritation in washed rabbit eyes; in unwashed rabbit eyes, there was mild conjunctival irritation, minimal iritis, but no corneal effects. Adipic acid dust may irritate the mucous membranes of the lungs and nose. In a 2-year feeding study, rats fed adipic acid at concentrations up to 5% in the diet exhibited only weight loss. Adipic acid is not genetically active in a wide variety of assay systems. Adipic acid caused no developmental toxicity in mice, rats, rabbits, or hamsters when administered orally. Adipic acid is partially metabolized in humans; the balance is eliminated unchanged in the urine. Adipic acid is slightly to moderately toxic to fish, daphnia, and algae in acute tests.

  3. Acid Thunder: Acid Rain and Ancient Mesoamerica

    ERIC Educational Resources Information Center

    Kahl, Jonathan D. W.; Berg, Craig A.

    2006-01-01

    Much of Mesoamerica's rich cultural heritage is slowly eroding because of acid rain. Just as water dissolves an Alka-Seltzer tablet, acid rain erodes the limestone surfaces of Mexican archaeological sites at a rate of about one-half millimeter per century (Bravo et al. 2003). A half-millimeter may not seem like much, but at this pace, a few…

  4. Quantity of acid in acid fog

    SciTech Connect

    Deal, W.J.

    1983-07-01

    This communication notes the actual magnitude of the acidity in acidic fog particles and suggests a possible line of inquiry into the health effects of such fog so that it can be determined whether a typical fog is detrimental or beneficial relative to dry air.

  5. Purification of oleic acid and linoleic acid

    SciTech Connect

    Arudi, R.L.; Sutherland, M.W.; Bielski, B.H.J.

    1983-01-01

    To permit kinetic studies of the reactivity of unsaturated fatty acids towards oxygen radicals, it is essential to remove traces of hydroperoxides and other conjugated lipid impurities commonly present in commercial samples. Removal of these impurities has been satisfactorily achieved for oleic and linoleic acids by anaerobic low temperature recrystallization from acetonitrile. The uv spectra of commercial and purified samples are compared.

  6. Acid Thunder: Acid Rain and Ancient Mesoamerica

    ERIC Educational Resources Information Center

    Kahl, Jonathan D. W.; Berg, Craig A.

    2006-01-01

    Much of Mesoamerica's rich cultural heritage is slowly eroding because of acid rain. Just as water dissolves an Alka-Seltzer tablet, acid rain erodes the limestone surfaces of Mexican archaeological sites at a rate of about one-half millimeter per century (Bravo et al. 2003). A half-millimeter may not seem like much, but at this pace, a few…

  7. Acid-fast stain

    MedlinePlus

    ... this page: //medlineplus.gov/ency/article/003766.htm Acid-fast stain To use the sharing features on this page, please enable JavaScript. The acid-fast stain is a laboratory test that determines ...

  8. Valproic Acid and Pregnancy

    MedlinePlus

    ... live chat Live Help Fact Sheets Share Valproic Acid and Pregnancy Wednesday, 01 July 2015 In every ... This sheet talks about whether exposure to valproic acid may increase the risk for birth defects over ...

  9. Azelaic Acid Topical

    MedlinePlus

    Azelaic acid gel and foam is used to clear the bumps, lesions, and swelling caused by rosacea (a skin ... redness, flushing, and pimples on the face). Azelaic acid cream is used to treat the pimples and ...

  10. Deoxycholic Acid Injection

    MedlinePlus

    Deoxycholic acid injection is used to improve the appearance and profile of moderate to severe submental fat ('double chin'; fatty tissue located under the chin). Deoxycholic acid injection is in a class of medications called ...

  11. Uric Acid Test

    MedlinePlus

    ... products and services. Advertising & Sponsorship: Policy | Opportunities Uric Acid Share this page: Was this page helpful? Also known as: Serum Urate; UA Formal name: Uric Acid Related tests: Synovial Fluid Analysis , Kidney Stone Analysis , ...

  12. Methylmalonic Acid Test

    MedlinePlus

    ... products and services. Advertising & Sponsorship: Policy | Opportunities Methylmalonic Acid Share this page: Was this page helpful? Also known as: MMA Formal name: Methylmalonic Acid Related tests: Vitamin B12 and Folate , Homocysteine , Intrinsic ...

  13. Zoledronic Acid Injection

    MedlinePlus

    Zoledronic acid (Reclast) is used to prevent or treat osteoporosis (condition in which the bones become thin and weak ... of life,' end of regular menstrual periods). Zoledronic acid (Reclast) is also used to treat osteoporosis in ...

  14. Hydrochloric acid poisoning

    MedlinePlus

    Hydrochloric acid is a clear, poisonous liquid. It is highly corrosive, which means it immediately causes severe damage, such ... poisoning due to swallowing or breathing in hydrochloric acid. This article is for information only. Do NOT ...

  15. Aminocaproic Acid Injection

    MedlinePlus

    Aminocaproic acid injection is used to control bleeding that occurs when blood clots are broken down too quickly. This ... the baby is ready to be born). Aminocaproic acid injection is also used to control bleeding in ...

  16. Omega-6 Fatty Acids

    MedlinePlus

    ... types of fats. Some types are found in vegetable oils, including corn, evening primrose seed, safflower, and soybean ... from studying specific omega-6 fatty acids or plant oils containing omega-6 fatty acids. See the separate ...

  17. Fatty acid analogs

    DOEpatents

    Elmaleh, David R.; Livni, Eli

    1985-01-01

    In one aspect, a radioactively labeled analog of a fatty acid which is capable of being taken up by mammalian tissue and which exhibits an in vivo beta-oxidation rate below that with a corresponding radio