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1
Sakane, Fumio, Fumi Hoshino, and Chiaki Murakami. "New Era of Diacylglycerol Kinase, Phosphatidic Acid and Phosphatidic Acid-Binding Protein." International Journal of Molecular Sciences 21, no. 18 (September 16, 2020): 6794. http://dx.doi.org/10.3390/ijms21186794.
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Diacylglycerol kinase (DGK) phosphorylates diacylglycerol (DG) to generate phosphatidic acid (PA). Mammalian DGK consists of ten isozymes (α–κ) and governs a wide range of physiological and pathological events, including immune responses, neuronal networking, bipolar disorder, obsessive-compulsive disorder, fragile X syndrome, cancer, and type 2 diabetes. DG and PA comprise diverse molecular species that have different acyl chains at the sn-1 and sn-2 positions. Because the DGK activity is essential for phosphatidylinositol turnover, which exclusively produces 1-stearoyl-2-arachidonoyl-DG, it has been generally thought that all DGK isozymes utilize the DG species derived from the turnover. However, it was recently revealed that DGK isozymes, except for DGKε, phosphorylate diverse DG species, which are not derived from phosphatidylinositol turnover. In addition, various PA-binding proteins (PABPs), which have different selectivities for PA species, were recently found. These results suggest that DGK–PA–PABP axes can potentially construct a large and complex signaling network and play physiologically and pathologically important roles in addition to DGK-dependent attenuation of DG–DG-binding protein axes. For example, 1-stearoyl-2-docosahexaenoyl-PA produced by DGKδ interacts with and activates Praja-1, the E3 ubiquitin ligase acting on the serotonin transporter, which is a target of drugs for obsessive-compulsive and major depressive disorders, in the brain. This article reviews recent research progress on PA species produced by DGK isozymes, the selective binding of PABPs to PA species and a phosphatidylinositol turnover-independent DG supply pathway.
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Zegarlinska, Jolanta, Magda Piaścik, Aleksander F. Sikorski, and Aleksander Czogalla. "Phosphatidic acid – a simple phospholipid with multiple faces." Acta Biochimica Polonica 65, no. 2 (July 8, 2018): 163–71. http://dx.doi.org/10.18388/abp.2018_2592.
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Phosphatidic acid (PA) is the simplest glycerophospholipid naturally occurring in living organisms, and even though its content among other cellular lipids is minor, it is drawing more and more attention due to its multiple biological functions. PA is a precursor for other phospholipids, acts as a lipid second messenger and, due to its structural properties, is also a modulator of membrane shape. Although much is known about interaction of PA with its effectors, the molecular mechanisms remain unresolved to a large degree. Throughout many of the well-characterized PA cellular sensors, no conserved binding domain can be recognized. Moreover, not much is known about the cellular dynamics of PA and how it is distributed among subcellular compartments. Remarkably, PA can play distinct roles within each of these compartments. For example, in the nucleus it behaves as a mitogen, influencing gene expression regulation, and in the Golgi membrane it plays a role in membrane trafficking. Here we discuss how a biophysical experimental approach enabled PA behavior to be described in the context of a lipid bilayer and to what extent various physicochemical conditions may modulate the functional properties of the lipid. Understanding these aspects would help to unravel specific mechanisms of PA-driven membrane transformation and protein recruitment and thus would lead to a clearer picture of the biological role of PA.
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Huang, Shanjin, Lisa Gao, Laurent Blanchoin, and Christopher J. Staiger. "Heterodimeric Capping Protein fromArabidopsisIs Regulated by Phosphatidic Acid." Molecular Biology of the Cell 17, no. 4 (April 2006): 1946–58. http://dx.doi.org/10.1091/mbc.e05-09-0840.
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The cytoskeleton is a key regulator of morphogenesis, sexual reproduction, and cellular responses to extracellular stimuli. Changes in the cellular architecture are often assumed to require actin-binding proteins as stimulus-response modulators, because many of these proteins are regulated directly by binding to intracellular second messengers or signaling phospholipids. Phosphatidic acid (PA) is gaining widespread acceptance as a major, abundant phospholipid in plants that is required for pollen tube tip growth and mediates responses to osmotic stress, wounding, and phytohormones; however, the number of identified effectors of PA is rather limited. Here we demonstrate that exogenous PA application leads to significant increases in filamentous actin levels in Arabidopsis suspension cells and poppy pollen grains. To investigate further these lipid-induced changes in polymer levels, we analyzed the properties of a key regulator of actin filament polymerization, the heterodimeric capping protein from Arabidopsis thaliana (AtCP). AtCP binds to PA with a Kdvalue of 17 μM and stoichiometry of ∼1:2. It also binds well to PtdIns(4,5)P2, but not to several other phosphoinositide or acidic phospholipids. The interaction with PA inhibited the actin-binding activity of CP. In the presence of PA, CP is unable to block the barbed or rapidly growing and shrinking end of actin filaments. Precapped filament barbed ends can also be uncapped by addition of PA, allowing rapid filament assembly from an actin monomer pool that is buffered with profilin. The findings support a model in which the inhibition of CP activity in cells by elevated PA results in the stimulation of actin polymerization from a large pool of profilin-actin. Such regulation may be important for the response of plant cells to extracellular stimuli as well as for the normal process of pollen tube tip growth.
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Baba, Takashi, Yuriko Kashiwagi, Nagisa Arimitsu, Takeshi Kogure, Ayumi Edo, Tomohiro Maruyama, Kazuki Nakao, et al. "Phosphatidic Acid (PA)-preferring Phospholipase A1Regulates Mitochondrial Dynamics." Journal of Biological Chemistry 289, no. 16 (March 5, 2014): 11497–511. http://dx.doi.org/10.1074/jbc.m113.531921.
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Henry, R. A., S. Y. Boyce, T. Kurz, and R. A. Wolf. "Stimulation and binding of myocardial phospholipase C by phosphatidic acid." American Journal of Physiology-Cell Physiology 269, no. 2 (August 1, 1995): C349—C358. http://dx.doi.org/10.1152/ajpcell.1995.269.2.c349.
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Exposure of adult ventricular myocytes to exogenous natural phosphatidic acid results in the production of inositol phosphates by unknown mechanism(s). We characterized stimulation of myocytic phosphoinositide-specific phospholipase C (PLC) by synthetic dioleoyl phosphatidic acid (PA) as a potential mechanism for modulation of inositol phosphate production. Our data demonstrate that exogenous PA, at 10(-8)-10(-5) M, caused a concentration-dependent increase in inositol 1,4,5-trisphosphate in adult rabbit ventricular myocytes. PA also caused a concentration-dependent increase in in vitro activity of myocytic PLC in the presence or absence of ethylene glycol-bis(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid (EGTA). PLC-delta 1, the predominant isozyme of PLC expressed in adult rabbit ventricular myocytes, bound to liposomes of PA with high affinity in the presence of EGTA. The phosphomonoester group of PA was critical to in vitro stimulation of myocytic PLC activity and high-affinity binding of PLC-delta 1. We propose that binding of PLC-delta 1 to phosphatidic acid may be a novel mechanism for dynamic membrane association and modulation of PLC in adult ventricular myocytes.
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Ganesan, Suriakarthiga, Brittney N. Shabits, and Vanina Zaremberg. "Tracking Diacylglycerol and Phosphatidic Acid Pools in Budding Yeast." Lipid Insights 8s1 (January 2015): LPI.S31781. http://dx.doi.org/10.4137/lpi.s31781.
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Phosphatidic acid (PA) and diacylglycerol (DAG) are key signaling molecules and important precursors for the biosynthesis of all glycerolipids found in eukaryotes. Research conducted in the model organism Saccharomyces cerevisiae has been at the forefront of the identification of the enzymes involved in the metabolism and transport of PA and DAG. Both these lipids can alter the local physical properties of membranes by introducing negative curvature, but the anionic nature of the phosphomonoester headgroup in PA sets it apart from DAG. As a result, the mechanisms underlying PA and DAG interaction with other lipids and proteins are notoriously different. This is apparent from the analysis of the protein domains responsible for recognition and binding to each of these lipids. We review the current evidence obtained using the PA-binding proteins and domains fused to fluorescent proteins for in vivo tracking of PA pools in yeast. In addition, we present original results for visualization of DAG pools in yeast using the C1 domain from mammalian PKCδ. An emerging first cellular map of the distribution of PA and DAG pools in actively growing yeast is discussed.
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Noh, Ji-Yoon, Kyung-Min Lim, Ok-Nam Bae, Seung-Min Chung, Sang-Wook Lee, Kyung-Mi Joo, Sin-Doo Lee, and Jin-Ho Chung. "Procoagulant and prothrombotic activation of human erythrocytes by phosphatidic acid." American Journal of Physiology-Heart and Circulatory Physiology 299, no. 2 (August 2010): H347—H355. http://dx.doi.org/10.1152/ajpheart.01144.2009.
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Increased phosphatidic acid (PA) and phospholipase D (PLD) activity are frequently observed in various disease states including cancers, diabetes, sepsis, and thrombosis. Previously, PA has been regarded as just a precursor for lysophosphatidic acid (LPA) and diacylglycerol (DAG). However, increasing evidence has suggested independent biological activities of PA itself. In the present study, we demonstrated that PA can enhance thrombogenic activities in human erythrocytes through phosphatidylserine (PS) exposure in a Ca2+-dependent manner. In freshly isolated human erythrocytes, treatment of PA or PLD induced PS exposure. PA-induced PS exposure was not attenuated by inhibitors of phospholipase A2or phosphatidate phosphatase, which converts PA to LPA or DAG. An intracellular Ca2+increase and the resultant activation of Ca2+-dependent PKC-α appeared to underlie the PA-induced PS exposure through the activation of scramblase. A marginal decrease in flippase activity was also noted, contributing further to the maintenance of exposed PS on the outer membrane. PA-treated erythrocytes showed strong thrombogenic activities, as demonstrated by increased thrombin generation, endothelial cell adhesion, and erythrocyte aggregation. Importantly, these procoagulant activations by PA were confirmed in a rat in vivo venous thrombosis model, where PA significantly enhanced thrombus formation. In conclusion, these results suggest that PA can induce thrombogenic activities in erythrocytes through PS exposure, which can increase thrombus formation and ultimately contribute to the development of cardiovascular diseases.
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Nanjundan, Meera, and Fred Possmayer. "Pulmonary phosphatidic acid phosphatase and lipid phosphate phosphohydrolase." American Journal of Physiology-Lung Cellular and Molecular Physiology 284, no. 1 (January 1, 2003): L1—L23. http://dx.doi.org/10.1152/ajplung.00029.2002.
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The lung contains two distinct forms of phosphatidic acid phosphatase (PAP). PAP1 is a cytosolic enzyme that is activated through fatty acid-induced translocation to the endoplasmic reticulum, where it converts phosphatidic acid (PA) to diacylglycerol (DAG) for the biosynthesis of phospholipids and neutral lipids. PAP1 is Mg2+ dependent and sulfhydryl reagent sensitive. PAP2 is a six-transmembrane-domain integral protein localized to the plasma membrane. Because PAP2 degrades sphingosine-1-phosphate (S1P) and ceramide-1-phosphate in addition to PA and lyso-PA, it has been renamed lipid phosphate phosphohydrolase (LPP). LPP is Mg2+independent and sulfhydryl reagent insensitive. This review describes LPP isoforms found in the lung and their location in signaling platforms (rafts/caveolae). Pulmonary LPPs likely function in the phospholipase D pathway, thereby controlling surfactant secretion. Through lowering the levels of lyso-PA and S1P, which serve as agonists for endothelial differentiation gene receptors, LPPs regulate cell division, differentiation, apoptosis, and mobility. LPP activity could also influence transdifferentiation of alveolar type II to type I cells. It is considered likely that these lipid phosphohydrolases have critical roles in lung morphogenesis and in acute lung injury and repair.
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Kim, Sang-Chul, and Xuemin Wang. "Phosphatidic acid: an emerging versatile class of cellular mediators." Essays in Biochemistry 64, no. 3 (July 9, 2020): 533–46. http://dx.doi.org/10.1042/ebc20190089.
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Abstract Lipids function not only as the major structural components of cell membranes, but also as molecular messengers that transduce signals to trigger downstream signaling events in the cell. Phosphatidic acid (PA), the simplest and a minor class of glycerophospholipids, is a key intermediate for the synthesis of membrane and storage lipids, and also plays important roles in mediating diverse cellular and physiological processes in eukaryotes ranging from microbes to mammals and higher plants. PA comprises different molecular species that can act differently, and is found in virtually all organisms, tissues, and organellar membranes, with variations in total content and molecular species composition. The cellular levels of PA are highly dynamic in response to stimuli and multiple enzymatic reactions can mediate its production and degradation. Moreover, its unique physicochemical properties compared with other glycerophospholipids allow PA to influence membrane structure and dynamics, and interact with various proteins. PA has emerged as a class of new lipid mediators modulating various signaling and cellular processes via its versatile effects, such as membrane tethering, conformational changes, and enzymatic activities of target proteins, and vesicular trafficking.
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Antonescu, Costin N., Gaudenz Danuser, and Sandra L. Schmid. "Phosphatidic Acid Plays a Regulatory Role in Clathrin-mediated Endocytosis." Molecular Biology of the Cell 21, no. 16 (August 15, 2010): 2944–52. http://dx.doi.org/10.1091/mbc.e10-05-0421.
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Clathrin-mediated endocytosis (CME) is the main route of internalization of receptor-ligand complexes. Relatively little is known about the role of specific lipids in CME, in particular that of phosphatidic acid (PA). We examined the effect of altering cellular PA levels on CME by manipulating the activities and/or levels of either phospholipase D (PLD1 and PLD2) or diacylglycerol kinase (DGK), two enzyme classes involved in PA production. DGK inhibition resulted in a dramatic reduction of cellular PA, measured directly using an enzyme-coupled reaction, which resulted in a decreased rate of EGFR internalization measured biochemically. This corresponded to a decreased rate of clathrin-coated pit (CCP) initiation and increased lifetimes of productive CCPs, as determined by quantitative live-cell total internal reflection fluorescence microscopy. Unexpectedly, PLD inhibition caused an increase in cellular PA, suggesting that PLD activity negatively regulates PA synthesis by other more productive pathways. Consistent with opposite effects on cellular PA levels, PLD inhibition had opposite effects on EGFR internalization and CCP dynamics, compared with DGK inhibition. Importantly, the constitutive internalization of transferrin receptors was unaffected by either treatment. These findings demonstrate that PA plays a regulatory rather than obligatory role in CME and differentially regulates ligand-stimulated CME of EGFR.
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Xu, Y. J., V. Panagia, Q. Shao, X. Wang, and N. S. Dhalla. "Phosphatidic acid increases intracellular free Ca2+ and cardiac contractile force." American Journal of Physiology-Heart and Circulatory Physiology 271, no. 2 (August 1, 1996): H651—H659. http://dx.doi.org/10.1152/ajpheart.1996.271.2.h651.
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Although phosphatidic acid (PA) is mainly formed due to the hydrolysis of phosphatidylcholine by myocardial phospholipase D, its functional significance in the heart is not fully understood. The present study was designed to determine the effects of PA on intracellular free Ca2+ level ([Ca2+]i) in freshly isolated adult rat cardiomyocytes by using fura 2-acextoxmethylester and free fura 2 technique. Addition of PA at concentrations of 1–200 microM produced a concentration-dependent increase in [Ca2+]i from the basal level of 117 +/- 8 nM; maximal increase in [Ca2+]i was 233 +/- 50 nM, whereas median effective concentration (EC50) for PA was 45 +/- 1.2 microM. This increase in [Ca2+]i was abolished by the removal of extracellular Ca2+ with ethylene glycol-bis(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid and was partially attenuated by Ca2+ channel blockers, verapamil or diltiazem. Preincubation of cardiomyocytes with cyclopiazonic acid and thapsigargin or with ryanodine [to deplete sarcoplasmic reticulum (SR) Ca2+] attenuated the PA-induced increase in [Ca2+]i by 66, 37, and 43%, respectively. Furthermore, the response of [Ca2+]i to PA was blunted by 2-nitro-4 carboxyphenylcarbonate, an inhibitor of phospholipase C, but was unaffected by staurosporine, a protein kinase C inhibitor. PA was also observed to induce Ca2+ efflux from the myocytes. In addition, an injection of PA (0.34 microgram/100 g body wt i.v.) in rats produced a significant increase of the left ventricular developed pressure as well as the maximum rates of cardiac contraction and relaxation within 5 min. These data suggest that the PA-induced increase in [Ca2+]i in cardiomyocytes is a consequence of both Ca2+ influx from the extracellular source and Ca2+ release from the intracellular SR stores. Furthermore, these in vitro data suggest the possibility that PA may regulate [Ca2+]i and contractile parameters in the heart.
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Shad, Brandon James, Benoit Smeuninx, Philip James Atherton, and Leigh Breen. "The mechanistic and ergogenic effects of phosphatidic acid in skeletal muscle." Applied Physiology, Nutrition, and Metabolism 40, no. 12 (December 2015): 1233–41. http://dx.doi.org/10.1139/apnm-2015-0350.
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Skeletal muscle mass plays a vital role in locomotion, whole-body metabolic health, and is a positive predictor of longevity. It is well established the mammalian target of rapamycin (mTOR) is a central regulator of skeletal muscle protein turnover. The pursuit to find novel nutrient compounds or functional food sources that possess the ability to activate mTOR and promote skeletal muscle protein accretion has been on going. Over the last decade, a key role has been proposed for the phospholipid phosphatidic acid (PA) in mTOR activation. Mechanical load-induced (i.e., resistance exercise) intramuscular PA can directly bind to and activate mTOR. In addition, PA provided exogenously in cell culture heightens mTOR activity, albeit indirectly. Thus, endogenously generated PA and exogenous provision of PA appear to act through distinct mechanisms that converge on mTOR and, potentially, may amplify muscle protein synthesis. In support of this notion, limited evidence from humans suggests that resistance exercise training combined with oral supplemental PA enhances strength gains and muscle hypertrophy. However, the precise mechanisms underpinning the augmented muscle remodelling response with supplemental PA remain elusive. In this review, we will critically examine available evidence from cell cultures and animal and human experimental models to provide an overview of the mechanisms through which endogenous and exogenous PA may act to promote muscle anabolism, and discuss the potential for PA as a therapeutic tool to maintain or restore skeletal muscle mass in the context of ageing and disease.
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Tanguy, Emeline, Nawal Kassas, and Nicolas Vitale. "Protein–Phospholipid Interaction Motifs: A Focus on Phosphatidic Acid." Biomolecules 8, no. 2 (April 23, 2018): 20. http://dx.doi.org/10.3390/biom8020020.
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Cellular membranes are composed of thousands of different lipids usually maintained within a narrow range of concentrations. In addition to their well-known structural and metabolic roles, signaling functions for many lipids have also emerged over the last two decades. The latter largely depend on the ability of particular classes of lipids to interact specifically with a great variety of proteins and to regulate their localization and activity. Among these lipids, phosphatidic acid (PA) plays a unique role in a large repertoire of cellular activities, most likely in relation to its unique biophysical properties. However, until recently, only incomplete information was available to model the interaction between PA and its protein partners. The development of new liposome-based assays as well as molecular dynamic simulation are now providing novel information. We will review the different factors that have shown to modulate the capacity of PA to interact with specific domains in target proteins.
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Winter, Jeremiah N., Todd E. Fox, Mark Kester, Leonard S. Jefferson, and Scot R. Kimball. "Phosphatidic acid mediates activation of mTORC1 through the ERK signaling pathway." American Journal of Physiology-Cell Physiology 299, no. 2 (August 2010): C335—C344. http://dx.doi.org/10.1152/ajpcell.00039.2010.
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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.
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Gomez-Larrauri, Ana, Patricia Gangoiti, Natalia Presa, Asier Dominguez-Herrera, Chiara Donati, Paola Bruni, Miguel Trueba, Antonio Gomez-Muñoz, and Alberto Ouro. "Phosphatidic Acid Stimulates Myoblast Proliferation through Interaction with LPA1 and LPA2 Receptors." International Journal of Molecular Sciences 22, no. 3 (February 1, 2021): 1452. http://dx.doi.org/10.3390/ijms22031452.
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Phosphatidic acid (PA) is a bioactive phospholipid capable of regulating key biological functions, including neutrophil respiratory burst, chemotaxis, or cell growth and differentiation. However, the mechanisms whereby PA exerts these actions are not completely understood. In this work, we show that PA stimulates myoblast proliferation, as determined by measuring the incorporation of [3H]thymidine into DNA and by staining the cells with crystal violet. PA induced the rapid phosphorylation of Akt and ERK1/2, and pretreatment of the cells with specific small interferin RNA (siRNA) to silence the genes encoding these kinases, or with selective pharmacologic inhibitors, blocked PA-stimulated myoblast proliferation. The mitogenic effects of PA were abolished by the preincubation of the myoblasts with pertussis toxin, a Gi protein inhibitor, suggesting the implication of Gi protein-coupled receptors in this action. Although some of the effects of PA have been associated with its possible conversion to lysoPA (LPA), treatment of the myoblasts with PA for up to 60 min did not produce any significant amount of LPA in these cells. Of interest, pharmacological blockade of the LPA receptors 1 and 2, or specific siRNA to silence the genes encoding these receptors, abolished PA-stimulated myoblast proliferation. Moreover, PA was able to compete with LPA for binding to LPA receptors, suggesting that PA can act as a ligand of LPA receptors. It can be concluded that PA stimulates myoblast proliferation through interaction with LPA1 and LPA2 receptors and the subsequent activation of the PI3K/Akt and MEK/ERK1-2 pathways, independently of LPA formation.
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MIAO, Qi, Xuehai HAN, and Fuyu YANG. "Phosphatidic acid–phosphatidylethanolamine interaction and apocytochrome c translocation across model membranes." Biochemical Journal 354, no. 3 (March 8, 2001): 681–88. http://dx.doi.org/10.1042/bj3540681.
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The translocation of apocytochrome c (apocyt.c) across large unilamellar vesicles (LUVs) constructed from mixtures of anionic and zwitterionic phospholipids, phosphatidylethanolamine (PE) and phosphatidylcholine (PC), has been studied. It was shown that the import ratio of horse heart apocyt.c in LUVs composed of phosphatidic acid (PA) combined with PE and PC (62±10%) was much higher than that in LUVs made of PE and PC plus any other acidic phospholipid species (20±5%). This feature was shared by tuna heart and chicken heart apocyt.c. In addition, the greater efficiency of the PA/PE/PC system versus others in facilitating apocyt.c translocation was maintained using synthetic anionic phospholipids with the same acyl chains. Besides, apocyt.c induces more leakage of entrapped fluorescein sulphonate (FS) from the interior of PA/PC/PE vesicles compared with phosphatidylglycerol (PG)/PC/PE ones. By measuring the intrinsic fluorescence emission spectrum and the accessibility of the preprotein to the fluorescence quencher, acrylamide, differences could be detected in the conformational changes of apocyt.c as a consequence of its interaction with PA/PE/PC and PG/PE/PC vesicles, respectively. Particularly notable is that PE is indispensable for the PA/PE/PC system to most efficiently facilitate apocyt.c translocation across the model membranes. With the fraction of PE increasing from 0 to 30 mol%, the translocation efficiency of apocyt.c as well as its ability to induce FS efflux was significantly enhanced in PA-containing LUVs, whereas this was not observed in the case of replacement of PA by PG or phosphatidylserine. It is also interesting to note that in LUVs containing PA, dioleoyl-PE, but not dielaidoyl-PE, can exert such influences, indicative of the role of non-bilayer formation propensity. On the basis of these results it is postulated that PA might increase the bilayer-destabilizing effects of PE, and hence increase the translocation efficiency of apocyt.c and its leakage-induction ability.
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Roos, Isabella, Fabrizia Ferracin, and Alfred Pletscher. "Interaction of Vasopressin with Human Blood Platelets: Dependency on Mg2+." Thrombosis and Haemostasis 56, no. 03 (1986): 260–62. http://dx.doi.org/10.1055/s-0038-1661662.
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SummaryArginine-vasopressin (AVP) in the presence of Mg2+ but not in the absence of bivalent cations led to accumulation of [32P]-phosphatidic acid ([32P]-PA) in human blood platelets. Mg2+ also enhanced the specific binding of [3H]-AVP to intact platelets. The concentrations of the cation which enabled AVP to cause half maximal rise of [32P]-PA and those inducing half maximal [3H]-AVP-binding were of the same order. It is concluded that the stimulation of phosphatidyl inositide breakdown by AVP in presence of Mg2+ is at least partially due to a Mg2+-induced enhancement of specific AVP-binding to the platelet membranes.
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Lutkewitte, Andrew J., and Brian N. Finck. "Regulation of Signaling and Metabolism by Lipin-mediated Phosphatidic Acid Phosphohydrolase Activity." Biomolecules 10, no. 10 (September 29, 2020): 1386. http://dx.doi.org/10.3390/biom10101386.
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Phosphatidic acid (PA) is a glycerophospholipid intermediate in the triglyceride synthesis pathway that has incredibly important structural functions as a component of cell membranes and dynamic effects on intracellular and intercellular signaling pathways. Although there are many pathways to synthesize and degrade PA, a family of PA phosphohydrolases (lipin family proteins) that generate diacylglycerol constitute the primary pathway for PA incorporation into triglycerides. Previously, it was believed that the pool of PA used to synthesize triglyceride was distinct, compartmentalized, and did not widely intersect with signaling pathways. However, we now know that modulating the activity of lipin 1 has profound effects on signaling in a variety of cell types. Indeed, in most tissues except adipose tissue, lipin-mediated PA phosphohydrolase activity is far from limiting for normal rates of triglyceride synthesis, but rather impacts critical signaling cascades that control cellular homeostasis. In this review, we will discuss how lipin-mediated control of PA concentrations regulates metabolism and signaling in mammalian organisms.
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Domínguez-González, Irene, Silvia N. Vázquez-Cuesta, Alicia Algaba, and F. Javier Díez-Guerra. "Neurogranin binds to phosphatidic acid and associates to cellular membranes." Biochemical Journal 404, no. 1 (April 26, 2007): 31–43. http://dx.doi.org/10.1042/bj20061483.
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Neurogranin (Ng) is a 78-amino-acid-long protein concentrated at dendritic spines of forebrain neurons that is involved in synaptic plasticity through the regulation of CaM (calmodulin)-mediated signalling. Ng features a central IQ motif that mediates binding to CaM and is phosphorylated by PKC (protein kinase C). We have analysed the subcellular distribution of Ng and found that it associates to cellular membranes in rat brain. In vitro binding assays revealed that Ng selectively binds to PA (phosphatidic acid) and that this interaction is prevented by CaM and PKC phosphorylation. Using the peptide Ng-(29–47) and a mutant with an internal deletion (Ng-IQless), we have shown that Ng binding to PA and to cellular membranes is mediated by its IQ motif. Ng expressed in NIH-3T3 cells accumulates at peripheral regions of the plasma membrane and localizes at intracellular vesicles that can be clearly visualized following saponin permeabilization. This distribution was affected by PLD (phospholipase D) and PIP5K (phosphatidylinositol 4-phosphate 5-kinase) overexpression. Based on these results, we propose that Ng binding to PA may be involved in Ng accumulation at dendritic spines and that Ng could modulate PA signalling in the postsynaptic environment.
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Noh, Ji-Yoon, Kyung-Min Lim, and Jin-Ho Chung. "Phosphatidic Acid Enhances Procoagulant Activity and Thrombosis through Phosphatidylserine Exposure in Human Erythrocytes." Blood 112, no. 11 (November 16, 2008): 3846. http://dx.doi.org/10.1182/blood.v112.11.3846.3846.
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Abstract The increased phospholipase D (PLD) activity and phosphatidic acid (PA) level are frequently observed in various disease states including cancers, diabetes, inflammation, sepsis, and thrombosis. While PA has been previously regarded as a precursor for lysophosphatidic acid (LPA) and diacylglycerol (DAG), increasing evidence suggests the biological activities of PA, itself. Here we demonstrated that the PA can enhance procoagulant activities in human erythrocytes and thrombus formation mediated through phosphatidylserine (PS) exposure. Conspicuously, the PS exposure by PA was substantially greater than that of LPA and we examined its mechanism of action in an effort to elucidate the biological significance of PA. In human erythrocytes, PA treatment resulted in PS exposure without microvesicle generation or hemolysis as determined by flow cytometry. These effects were not attenuated by inhibitors of phospholipase A2 and phosphatidate phosphatase, that convert PA to LPA and DAG, respectively, suggesting that PA directly induced PS exposure. PA exposed erythrocytes showed significantly high intracellular calcium level and resultant protein kinase C (PKC) a activation. Consistent with these findings, the activity of scramblase was enhanced by PA treatment, while that of flippase was inhibited. Furthermore, PA-exposed erythrocytes were aggregated, accelerated thrombin generation, and increased adherence to endothelial cells, implying PA treatment enhanced the thrombogenic activities of erythrocytes indeed. Of note, these procoagulant activations by PA were confirmed in rat in vivo venous thrombosis model. These results suggest that PA can contribute to enhanced thrombosis, mediated through PS exposure on erythrocytes. With this study, we believe a novel insight was given into the role of PA in cardiovascular diseases.
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Bursten, S. L., W. E. Harris, K. Resch, and D. H. Lovett. "Lipid A activation of glomerular mesangial cells: mimicry of the bioactive lipid, phosphatidic acid." American Journal of Physiology-Cell Physiology 262, no. 2 (February 1, 1992): C328—C338. http://dx.doi.org/10.1152/ajpcell.1992.262.2.c328.
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Lipid A, the active component of bacterial endotoxin, stimulates multiple cell types, including glomerular mesangial cells (MC), and yet the molecular mechanisms of cell activation remain unclear. Lipid A, in its monosaccharyl form, structurally resembles the biologically active lipid phosphatidic acid (PA). Given this, it was postulated that lipid A activates cells by acting as a structural and functional mimetic of PA. Lipid A was found to specifically stimulate an MC lyso-PA acyl transferase activity, leading to enhanced synthesis of sn-2-unsaturated forms of PA. Sn-2-unsaturated PA itself, in contrast to sn-2-saturated PA, also stimulated the lyso-PA acyl transferase activity, a positive feedback feature previously noted with lyso-lecithin acyl transferase. Structure-function correlations demonstrated that the phosphate moieties in both PA and lipid A were necessary to feedback stimulation of lyso-PA acyl transferase (AT), as dephosphorylated lipid A and 2-unsaturated 1,2-sn-diacylglycerol had no stimulatory effect on lyso-PA AT. The biologic relevance of the lipid A and PA-mediated increases in lyso-PA acyl transferase activity was shown, whereby limited exposure to these lipids rapidly induced identical MC morphologic and functional alterations characteristic of cellular activation. By mimicking the stimulatory action of PA, per se, on lyso-PA acyl transferase activity, lipid A may initiate a positive feedback cycle of acylation, yielding increased amounts of PA enriched in unsaturated fatty acids. This newly synthesized PA may subsequently act as the proximal mediator of cellular activation.
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Raghu, Padinjat, Elise Coessens, Maria Manifava, Plamen Georgiev, Trevor Pettitt, Eleanor Wood, Isaac Garcia-Murillas, et al. "Rhabdomere biogenesis in Drosophila photoreceptors is acutely sensitive to phosphatidic acid levels." Journal of Cell Biology 185, no. 1 (April 6, 2009): 129–45. http://dx.doi.org/10.1083/jcb.200807027.
Full textAbstract:
Phosphatidic acid (PA) is postulated to have both structural and signaling functions during membrane dynamics in animal cells. In this study, we show that before a critical time period during rhabdomere biogenesis in Drosophila melanogaster photoreceptors, elevated levels of PA disrupt membrane transport to the apical domain. Lipidomic analysis shows that this effect is associated with an increase in the abundance of a single, relatively minor molecular species of PA. These transport defects are dependent on the activation state of Arf1. Transport defects via PA generated by phospholipase D require the activity of type I phosphatidylinositol (PI) 4 phosphate 5 kinase, are phenocopied by knockdown of PI 4 kinase, and are associated with normal endoplasmic reticulum to Golgi transport. We propose that PA levels are critical for apical membrane transport events required for rhabdomere biogenesis.
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Arneja, J. S. "Effect of phosphate on lipid metabolism in Fusarium oxysporum." Acta Mycologica 23, no. 1 (August 20, 2014): 149–54. http://dx.doi.org/10.5586/am.1987.010.
Full textAbstract:
The effect of different phosphate levels in the growth medium on lipid metabolism in <i>Fusarium oxysporum</i>, was studied. An increase in the phosphate level led on to an increase in the phosphorus content of the mycelium, as well as in that of total lipids. However, higher phosphate concentrations, had no profound effect on the total lipid percentage. Among phospholipid compounds phosphatidic acid (PA) and phosphatidyl inositol were the most susceptible while phisphatidyl choline (PC) was found to be the least affected by changes in the phosphate content of the medium. In the pulse and chase experiments, higher specific activities were observed for PA, PGP and cardiolipin (CL) fractions.
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Kwiatek, Joanna M., and George M. Carman. "Yeast phosphatidic acid phosphatase Pah1 hops and scoots along the membrane phospholipid bilayer." Journal of Lipid Research 61, no. 8 (June 15, 2020): 1232–43. http://dx.doi.org/10.1194/jlr.ra120000937.
Full textAbstract:
PA phosphatase, encoded by PAH1 in the yeast Saccharomyces cerevisiae, catalyzes the Mg2+-dependent dephosphorylation of PA, producing DAG at the nuclear/ER membrane. This enzyme plays a major role in triacylglycerol synthesis and in the regulation of phospholipid synthesis. As an interfacial enzyme, PA phosphatase interacts with the membrane surface, binds its substrate, and catalyzes its reaction. The Triton X-100/PA-mixed micellar system has been utilized to examine the activity and regulation of yeast PA phosphatase. This system, however, does not resemble the in vivo environment of the membrane phospholipid bilayer. We developed an assay system that mimics the nuclear/ER membrane to assess PA phosphatase activity. PA was incorporated into unilamellar phospholipid vesicles (liposomes) composed of the major nuclear/ER membrane phospholipids, PC, PE, PI, and PS. We optimized this system to support enzyme-liposome interactions and to afford activity that is greater than that obtained with the aforementioned detergent system. Activity was regulated by phospholipid composition, whereas the enzyme’s interaction with liposomes was insensitive to composition. Greater activity was attained with large (≥100 nm) versus small (50 nm) vesicles. The fatty-acyl moiety of PA had no effect on this activity. PA phosphatase activity was dependent on the bulk (hopping mode) and surface (scooting mode) concentrations of PA, suggesting a mechanism by which the enzyme operates along the nuclear/ER membrane in vivo.
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Ktistakis, N. T., C. Delon, M. Manifava, E. Wood, I. Ganley, and J. M. Sugars. "Phospholipase D1 and potential targets of its hydrolysis product, phosphatidic acid." Biochemical Society Transactions 31, no. 1 (February 1, 2003): 94–97. http://dx.doi.org/10.1042/bst0310094.
Full textAbstract:
Phospholipase D (PLD) hydrolyses phosphatidylcholine into phosphatidic acid (PA) and choline. Our work aims to understand the properties of PLD1, and to identify downstream targets of PA. In one set of projects, we have focused on membrane-targeting mechanisms and have proposed a hierarchy of signals that allows PLD1 to localize to intracellular membranes. These signals involve a functional pleckstrin homology (PH) domain and its fatty acylation on two adjacent cysteine residues. A nearby Phox homology (PX) domain may modulate the function of the fatty acylated PH domain. This complex array of signals is probably necessitated by the targeting of PLD1 to multiple endocytic and secretory membranes under basal and signal-dependent conditions. In another set of projects, we have used chemically synthesized PA coupled to a solid support in order to identify proteins that interact with this phospholipid. Several proteins have emerged from this screen as potential targets. Some (e.g. ADP-ribosylation factor, coatomer β subunit) are involved in trafficking and their PA affinity can be understood in terms of their regulated cycling on and off membranes during rounds of transport. Others (sphingosine 1-phosphate kinase and PtdIns4P 5-kinase) are implicated in pathways that also involve PLD activation. Others still are novel proteins (brain-specific neurochondrin) whose affinity for PA may contribute to an understanding of their cellular function.
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Bursten, S. L., and W. E. Harris. "Interleukin-1 stimulates phosphatidic acid-mediated phospholipase D activity in human mesangial cells." American Journal of Physiology-Cell Physiology 266, no. 4 (April 1, 1994): C1093—C1104. http://dx.doi.org/10.1152/ajpcell.1994.266.4.c1093.
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Previous studies suggest that signal transduction mediated by interleukin-1 (IL-1), acting through an IL-1 receptor type found on T-cells and mesangial cells, may use phosphatidylethanolamine (PE) as a signaling molecule. Evidence presented here indicates that stimulation of human mesangial cells by IL-1 results in activation of a phospholipase D (PLD) that hydrolyzes PE to phosphatidic acid (PA). PLD acts on a subfraction of PE enriched in 1-o-alkyl and 1-o-alkenyl, sn-2-unsaturated species, generating a unique PA subspecies 30-120 s after stimulation. This PA species is subsequently converted to diradylglycerols by phosphatidate phosphohydrolase. The PE-directed PLD activity is abolished by antibodies against the IL-1 type I receptor and against IL-1. This specific PLD activity is also stimulated by low concentrations of 1,2-sn-dilinoleoyl PA, but not by high concentrations of 1-palmitoyl or 1-oleoyl lyso-PA. Blockade of PLD activation by IL-1 antibodies or antibody against the IL-1 receptor is bypassed by stimulation of human mesangial cells with 1,2-sn-dilinoleoyl PA. A novel system of signal cytokine mediation through PA self-amplification is indicated.
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el Bawab, S., O. Macovschi, M. Lagarde, and A. F. Prigent. "Time-course changes in content and fatty acid composition of phosphatidic acid from rat thymocytes during concanavalin A stimulation." Biochemical Journal 308, no. 1 (May 15, 1995): 113–18. http://dx.doi.org/10.1042/bj3080113.
Full textAbstract:
Several studies have shown the potential role of phosphatidic acid (PA) as a second messenger in different cell types. Thus, PA has been shown to mimic physiological agonists leading to various cellular responses, such as neurotransmitter and hormone release, cell proliferation by modulating DNA or RNA synthesis, the expression of several proto-oncogenes and growth factors, and the stimulation of enzyme activities such as phospholipase C (PLC), protein kinases and cyclic AMP (cAMP) phosphodiesterase. Stimulation of [3H]arachidonate-labelled rat thymocytes with the mitogen lectin concanavalin A (con A) resulted in enhanced production of radiolabelled PA after only 5 min of activation. The radiolabelled PA increase corresponded to a real increase in PA mass as determined by GLC quantification of its fatty acid content. In the presence of ethanol (0.5%), formation of phosphatidylethanol was not observed after 5 min of con A activation. Pretreatment of cells with R 59022 (10 microM), a diacylglycerol (DAG) kinase inhibitor, showed an inhibition in the formation of radiolabelled PA and in PA mass. These results suggest that the PLC-DAG kinase may be the pathway for PA synthesis in the first minutes of mitogenic thymocyte activation. A detailed analysis of the fatty acid composition showed that the relative amount of unsaturated fatty acids was increased in PA from stimulated cells concomitantly with a decrease in saturated ones; in particular, arachidonic acid was increased approximately 2-fold only 2 min after con A addition whereas palmitic acid was decreased for the whole period investigated (20 min). These changes favour the hydolysis of phosphoinositides rather than phosphatidylcholines by PLC. As PA remains a minor phospholipid, these changes are unlikely to affect cell membrane fluidity; but PA being now well recognized as a potential second messenger, its increased content as well as its increased unsaturation in the fatty acyl moiety might modulate several signalling pathways or the activity of enzymes such as cyclic nucleotide phosphodiesterase, controlling in this way the cellular level of cAMP, a negative regulator of blastic transformation.
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Toschi, Alfredo, Evan Lee, Limei Xu, Avalon Garcia, Noga Gadir, and David A. Foster. "Regulation of mTORC1 and mTORC2 Complex Assembly by Phosphatidic Acid: Competition with Rapamycin." Molecular and Cellular Biology 29, no. 6 (December 29, 2008): 1411–20. http://dx.doi.org/10.1128/mcb.00782-08.
Full textAbstract:
ABSTRACT mTOR, the mammalian target of rapamycin, is a critical node for control of cell growth and survival and has widely been implicated in cancer survival signals. mTOR exists in two complexes: mTORC1 and mTORC2. Phospholipase D (PLD) and its metabolite phosphatidic acid (PA) have been implicated in the regulation of mTOR; however, their role has been controversial. We report here that suppression of PLD prevents phosphorylation of the mTORC1 substrate S6 kinase (S6K) at Thr389 and the mTORC2 substrate Akt at Ser473. Suppression of PLD also blocked insulin-stimulated Akt phosphorylation at Ser473 and the mTORC2-dependent phosphorylation of PRAS40. Importantly, PA was required for the association of mTOR with Raptor to form mTORC1 and that of mTOR with Rictor to form mTORC2. The effect of PA was competitive with rapamycin—with much higher concentrations of rapamycin needed to compete with the PA-mTORC2 interaction than with PA-mTORC1. Suppressing PA production substantially increased the sensitivity of mTORC2 to rapamycin. Data provided here demonstrate a PA requirement for the stabilization of both mTORC1 and mTORC2 complexes and reveal a mechanism for the inhibitory effect of rapamycin on mTOR. This study also suggests that by suppressing PLD activity, mTORC2 could be targeted therapeutically with rapamycin.
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Longmuir, K. J., and L. A. Malinick. "Transfer of phosphatidic acid from liposomes to cells is collision dependent." American Journal of Physiology-Cell Physiology 256, no. 3 (March 1, 1989): C522—C531. http://dx.doi.org/10.1152/ajpcell.1989.256.3.c522.
Full textAbstract:
The kinetics of lipid transfer from unilamellar liposomes to cells in monolayer culture were determined for a fluorescent phosphatidic acid, 1-palmitoyl-2-[6-(7-nitrobenz-2-oxa-1,3-diazol-4-yl)aminocaproyl] -sn-glycerol 3-phosphate (C6-NBD-PA), and for the analogous phosphatidic acid without the fluorescent NBD group, 1-palmitoyl-2-caproyl-sn-[U-14C] glycerol 3-phosphate (C6-[14C]PA). Initial rates of liposome-to-cell transfer were measured at 2 degrees C under conditions in which the concentration of diffusible monomer in the aqueous medium was constant during the course of an experiment and was independent of total liposome concentration. Rates were similar for C6-NBD-PA and C6-[14C]PA, indicating that the NBD group does not significantly alter the transfer kinetics. It was found that liposome-to-cell transfer was dependent on 1) the mole fraction of diffusible lipid in the liposomes, 2) the liposome concentration, and 3) the cell density. The dependence of rate on the liposome concentration (observed under conditions in which aqueous monomer concentration remained constant) cannot be explained by a liposome-to-cell transfer mechanism involving the free diffusion of monomers through the aqueous medium. Instead, the data are consistent with a collision-dependent mechanism of monomer transfer that occurs when liposome and cell membranes come into contact but do not fuse.
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Hofbauer, Harald F., Michael Gecht, Sabine C. Fischer, Anja Seybert, Achilleas S. Frangakis, Ernst H. K. Stelzer, Roberto Covino, Gerhard Hummer, and Robert Ernst. "The molecular recognition of phosphatidic acid by an amphipathic helix in Opi1." Journal of Cell Biology 217, no. 9 (June 25, 2018): 3109–26. http://dx.doi.org/10.1083/jcb.201802027.
Full textAbstract:
A key event in cellular physiology is the decision between membrane biogenesis and fat storage. Phosphatidic acid (PA) is an important intermediate at the branch point of these pathways and is continuously monitored by the transcriptional repressor Opi1 to orchestrate lipid metabolism. In this study, we report on the mechanism of membrane recognition by Opi1 and identify an amphipathic helix (AH) for selective binding of PA over phosphatidylserine (PS). The insertion of the AH into the membrane core renders Opi1 sensitive to the lipid acyl chain composition and provides a means to adjust membrane biogenesis. By rational design of the AH, we tune the membrane-binding properties of Opi1 and control its responsiveness in vivo. Using extensive molecular dynamics simulations, we identify two PA-selective three-finger grips that tightly bind the PA phosphate headgroup while interacting less intimately with PS. This work establishes lipid headgroup selectivity as a new feature in the family of AH-containing membrane property sensors.
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Ha, K. S., and J. H. Exton. "Activation of actin polymerization by phosphatidic acid derived from phosphatidylcholine in IIC9 fibroblasts." Journal of Cell Biology 123, no. 6 (December 15, 1993): 1789–96. http://dx.doi.org/10.1083/jcb.123.6.1789.
Full textAbstract:
alpha-Thrombin induced a change in the cell morphology of IIC9 fibroblasts from a semiround to an elongated form, accompanied by an increase in stress fibers. Incubation of the cells with phospholipase D (PLD) from Streptomyces chromofuscus and exogenous phosphatidic acid (PA) caused similar morphological changes, whereas platelet-derived growth factor (PDGF) and phorbol 12-myristate 13-acetate (PMA) induced different changes, e.g., disruption of stress fibers and cell rounding. alpha-Thrombin, PDGF, and exogenous PLD increased PA by 20-40%, and PMA produced a smaller increase. alpha-Thrombin and exogenous PLD produced rapid increases in the amount of filamentous actin (F-actin) that were sustained for at least 60 min. However, PDGF produced a transient increase of F-actin at 1 min and PMA caused no significant change. Dioctanoylglycerol was ineffective except at 50 micrograms/ml. Phospholipase C from Bacillus cereus, which increased diacylglycerol (DAG) but not PA, did not change F-actin content. Down-regulation of protein kinase C (PKC) did not block actin polymerization induced by alpha-thrombin. H-7 was also ineffective. Exogenous PA activated actin polymerization with a significant effect at 0.01 microgram/ml and a maximal increase at 1 microgram/ml. No other phospholipids tested, including polyphosphoinositides, significantly activated actin polymerization. PDGF partially inhibited PA-induced actin polymerization after an initial increase at 1 min. PMA completely or largely blocked actin polymerization induced by PA or PLD. These results show that PC-derived PA, but not DAG or PKC, activates actin polymerization in IIC9 fibroblasts, and indicate that PDGF and PMA have inhibitory effects on PA-induced actin polymerization.
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Abraham, E., S. Bursten, R. Shenkar, J. Allbee, R. Tuder, P. Woodson, D. M. Guidot, G. Rice, J. W. Singer, and J. E. Repine. "Phosphatidic acid signaling mediates lung cytokine expression and lung inflammatory injury after hemorrhage in mice." Journal of Experimental Medicine 181, no. 2 (February 1, 1995): 569–75. http://dx.doi.org/10.1084/jem.181.2.569.
Full textAbstract:
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.
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TOOL, Anton T. J., Michela BLOM, Dirk ROOS, and Arthur J. VERHOEVEN. "Phospholipase D-derived phosphatidic acid is involved in the activation of the CD11b/CD18 integrin in human eosinophils." Biochemical Journal 340, no. 1 (May 10, 1999): 95–101. http://dx.doi.org/10.1042/bj3400095.
Full textAbstract:
Priming of human eosinophils is an essential event for the respiratory burst induced by serum-opsonized particles [serum-treated zymosan (STZ)]. In this study we have found that treatment of eosinophils with platelet-activating factor (PAF) leads to activation of phospholipase D. Inhibition of the formation of phospholipase D-derived products by ethanol resulted in about 90% inhibition of PAF-induced binding of fluorescent STZ particles to the cells, but only when ethanol was added to the cells before treatment with PAF. When ethanol was added after treatment with PAF, only a minor inhibition of the STZ binding and STZ-induced response was observed. These results indicate that phospholipase D-derived phosphatidic acid is involved in PAF priming, without having an effect on STZ stimulation. In the presence of propranolol, which inhibits phosphatidic acid-phosphatase activity, binding of STZ particles to human eosinophils induced by suboptimal concentrations of PAF was enhanced, indicating that phosphatidic acid and not diradylglyceride is the relevant molecule derived from phospholipase D activity. Addition of cell-permeant diC8-phosphatidic acid (DiC8-PA) to human eosinophils resulted in CD11b/CD18-dependent adhesion, both to STZ particles and fibronectin-coated wells, without significant upregulation of CD11b/CD18. The DiC8-PA-induced adhesion was not mediated via the fatty acid moiety, because other C8-lipids such as 1,2-diC8-phosphatidylcholine, 1-C8-monoacylglycerol or C8-ceramide were without effect. Activation of protein kinase C with PMA or 1,2-diC8-diacylglycerol did result in enhanced STZ binding. However, under these latter conditions upregulation of CD11b/CD18 was observed. Taken together, these results suggest that phospholipase D-derived PA is involved in changing the affinity of the CD11b/CD18 integrin for its ligands.
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SNITKO, Yana, Edward T. YOON, and Wonhwa CHO. "High specificity of human secretory class II phospholipase A2 for phosphatidic acid." Biochemical Journal 321, no. 3 (February 1, 1997): 737–42. http://dx.doi.org/10.1042/bj3210737.
Full textAbstract:
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≈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-PLA2Őtransition-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, Viodé, Rugani, Leballe, Ragab, Fournié, Sarda and Chap (1995) Cell 80, 919Ő927], these studies suggest that hs-PLA2 can rapidly hydrolyse PA molecules exposed to the outer layer of cell-derived microvesicles and thereby produce LPA.
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Jones, A. W., S. D. Shukla, and B. B. Geisbuhler. "Stimulation of phospholipase D activity and phosphatidic acid production by norepinephrine in rat aorta." American Journal of Physiology-Cell Physiology 264, no. 3 (March 1, 1993): C609—C616. http://dx.doi.org/10.1152/ajpcell.1993.264.3.c609.
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We sought to relate norepinephrine (NE) stimulation of phosphatidic acid (PA) production to functional responses of rat aorta and pathways for PA production. The time course for changes in PA was closely related to Ca-dependent tonic responses in 42K efflux and contraction. NE (30 microM for 1 min) increased PA and reduced phosphatidylcholine (PC) and phosphatidylinositol (PI) based on Pi analyses and 32P labeling of phospholipids. The 32P-to-Pi ratio in PA (0.8 +/- 0.2, n = 13) was similar to PC (0.8 +/- 0.1, n = 14) but was significantly lower (P < 0.001) than PI (4.6 +/- 0.5, n = 14). The 32P-to-Pi ratio in PA was also lower (P < 0.02) than phosphatidylinositol phosphate and phosphatidylinositol bisphosphate. NE also increased [3H]PA twofold (P < 0.05) when PC was selectively labeled with [3H]myristic acid. These observations are more consistent with PA being formed from the hydrolysis of PC by phospholipase D (PLD) than by the phosphorylation of diacylglycerol produced by the action of phospholipase C. PLD was assayed by the formation of phosphatidylethanol (PEt) via a transphosphatidylation reaction with ethanol (half-maximal stimulation at 0.4-0.5% vol/vol). The time course for PLD stimulation by NE was similar to PA, with significant increases (P < 0.002) during 10 s to 30 min exposure. Once formed, PEt was degraded slowly, with a half time > 3 h. It is concluded that NE stimulates PLD in rat aorta, which forms a significant amount of PA from the hydrolysis of PC.(ABSTRACT TRUNCATED AT 250 WORDS)
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Bohdanowicz, Michal, Daniel Schlam, Martin Hermansson, David Rizzuti, Gregory D. Fairn, Takehiko Ueyama, Pentti Somerharju, Guangwei Du, and Sergio Grinstein. "Phosphatidic acid is required for the constitutive ruffling and macropinocytosis of phagocytes." Molecular Biology of the Cell 24, no. 11 (June 2013): 1700–1712. http://dx.doi.org/10.1091/mbc.e12-11-0789.
Full textAbstract:
Macrophages and dendritic cells continuously survey their environment in search of foreign particles and soluble antigens. Such surveillance involves the ongoing extension of actin-rich protrusions and the consequent formation of phagosomes and macropinosomes. The signals inducing this constitutive cytoskeletal remodeling have not been defined. We report that, unlike nonphagocytic cells, macrophages and immature dendritic cells have elevated levels of phosphatidic acid (PA) in their plasma membrane. The plasmalemmal PA is synthesized by phosphorylation of diacylglycerol, which is in turn generated by a G protein–stimulated phospholipase C. Inhibition of diacylglycerol kinase activity results in the detachment of T-cell lymphoma invasion and metastasis–inducing protein 1 (TIAM1)—a Rac guanine exchange factor—from the plasma membrane, thereby depressing Rac activity and abolishing the constitutive ruffling and macropinocytosis that characterize macrophages and immature dendritic cells. Accumulation of PA and binding of TIAM1 to the membrane require the activity of phosphatidylinositol-4,5-bisphosphate 3-kinase. Thus a distinctive, constitutive pathway of PA biosynthesis promotes the actin remodeling required for immune surveillance.
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Gonzalez, Adam M., Katie M. Sell, Jamie J. Ghigiarelli, Christopher F. Kelly, Edward W. Shone, Matthew R. Accetta, Jamie B. Baum, and Gerald T. Mangine. "Effects of phosphatidic acid supplementation on muscle thickness and strength in resistance-trained men." Applied Physiology, Nutrition, and Metabolism 42, no. 4 (April 2017): 443–48. http://dx.doi.org/10.1139/apnm-2016-0564.
Full textAbstract:
The purpose of this study was to investigate the effects of phosphatidic acid (PA) supplementation on muscle thickness and strength following an 8 week supervised resistance-training program. Fifteen resistance trained men (22.8 ± 3.5 years; 80.6 ± 8.7 kg; 178.1 ± 5.6 cm; 14.6% ± 8.8% body fat) were randomly assigned to a group that either consumed 750 mg of PA or a placebo (PL). Testing was carried out before (PRE) and after (POST) training/supplementation for muscle thickness and strength. Muscle thickness of the rectus femoris (RF), vastus lateralis (VL), biceps brachii (BB), and triceps brachii (TB) muscles were measured via ultrasonography, along with 1 repetition maximum (1RM) of squat, deadlift, and bench press. Analysis of covariance (ANCOVA), using PRE values as the covariate, did not reveal any group differences for measures of muscle thickness in the RF (PA: 3.6% ± 5.2%; PL: 3.2% ± 4.2%, p = 0.97), VL (PA: 23.4% ± 18.1%, PL: 12.5% ± 15.4%, p = 0.37), BB (PA: 3.7% ± 6.4%, PL: 9.6% ± 12.4%, p = 0.86), or TB (PA: 15.1% ± 17.9%, PL: 10.7% ± 19.3%, p = 0.79). Likewise, no group differences were observed in changes in squat (PA: 8.4% ± 4.1%, PL: 8.1% ± 4.2%, p = 0.79), deadlift (PA: 10.1% ± 10.1%, PL: 8.9% ± 9.5%, p = 0.66), or bench press (PA: 5.7% ± 5.5%, PL: 5.1% ± 3.0%, p = 0.76) exercises. Collectively, however, all participants experienced significant (p < 0.05) improvements in each measure of muscle thickness and strength. Results of this study suggest that PA supplementation, in combination with a 3 days·week−1 resistance-training program for 8 weeks, did not have a differential effect compared with PL on changes in muscle thickness or 1RM strength.
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Cao, Chunyan, Peipei Wang, Hongdi Song, Wen Jing, Like Shen, Qun Zhang, and Wenhua Zhang. "Phosphatidic acid binds to and regulates guanine nucleotide exchange factor 8 (GEF8) activity in Arabidopsis." Functional Plant Biology 44, no. 10 (2017): 1029. http://dx.doi.org/10.1071/fp17113.
Full textAbstract:
Phosphatidic acid (PA) forms part of plant lipid metabolism and is a signalling molecule used in response to various external stresses. Guanine nucleotide exchange factors (GEFs) activate small GTPase ROPs, serving as molecular switches in a wide range of signalling pathways. However, the interaction between PA and GEFs in plants has not yet been reported. Here we show that PA bound specifically to GEF8 by using fat-Western blot and isothermal titration calorimetry assays. A C-terminal truncation of GEF8 exhibited strong PA binding, and mutation of lysines 13 and 18 in GEF8 PRONE domain caused a total loss of binding to PA. Two ROPs, ROP7 and ROP10, were identified as preferred substrates of GEF8 by pull-down and bimolecular fluorescence complementation assays. GEF8 activity towards ROP7, but not ROP10, was stimulated by PA both in vitro and in cells. Moreover, the PA- or ABA-induced activation of GEF8 was completely lost in the mutant GEF8, which did not bind to PA. Together, these findings identify a direct interconnection between PA-mediated GEFs activity and small GTPase signalling in plants and provide evidence for a synergistic activation of GEF8 by direct PA-binding to its PRONE domain.
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Vajanaphanich, M., U. Kachintorn, K. E. Barrett, J. A. Cohn, K. Dharmsathaphorn, and A. Traynor-Kaplan. "Phosphatidic acid modulates Cl- secretion in T84 cells: varying effects depending on mode of stimulation." American Journal of Physiology-Cell Physiology 264, no. 5 (May 1, 1993): C1210—C1218. http://dx.doi.org/10.1152/ajpcell.1993.264.5.c1210.
Full textAbstract:
Cl- secretion in T84 cells evoked by a stimulus that activates protein kinase C, carbachol, was associated with elevated levels of 32P-labeled phosphatidic acid (PA). PA's role in the regulation of Cl- secretion was explored by examining the effect of exogenous PA (10(-4) M) on Cl- secretion and intracellular Ca2+ levels ([Ca2+]i) in monolayers. PA potentiated the effect of carbachol on [Ca2+]i and Cl- secretion, although it did not stimulate Cl- secretion by itself. PA had divergent effects on cyclic nucleotide-dependent Cl- secretion. It delayed Cl- secretion induced by vasoactive intestinal polypeptide [VIP, adenosine 3',5'-cyclic monophosphate (cAMP) dependent] but potentiated that induced by the heat-stable enterotoxin of Escherichia coli (STa; guanosine 3',5'-cyclic monophosphate dependent). PA did not alter AMP or GMP levels, suggesting that PA acts at a site distal to the generation of these second messengers. PA caused a slight increase in phosphorylation of protein kinase C substrates but not of cAMP-dependent protein kinase substrates. However, PA is probably not acting through a classical protein kinase C pathway, because we have previously shown that phorbol esters inhibit carbachol's actions, and the protein kinase C inhibitor staurosporine failed to block the effect of PA on VIP- or STa-stimulated Cl- secretion. Thus PA differentially regulates stimulated Cl- secretion in T84 cells, depending on the nature of the agonist.
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Baker, Carol A., Kevin Desrosiers, and Joseph W. Dolan. "Propranolol Inhibits Hyphal Development in Candida albicans." Antimicrobial Agents and Chemotherapy 46, no. 11 (November 2002): 3617–20. http://dx.doi.org/10.1128/aac.46.11.3617-3620.2002.
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ABSTRACT Propranolol was used to investigate the role of phosphatidic acid (PA) and diacylglycerol in the dimorphic transition in Candida albicans. Propranolol was able to inhibit the appearance of germ tubes without decreasing growth rate. Data suggest that inhibition of morphogenesis may be due to binding by propranolol of PA derived from PLD1 hydrolysis of phosphatidylcholine.
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Klimecka, Maria, Maria Bucholc, Justyna Maszkowska, Ewa Krzywińska, Grażyna Goch, Małgorzata Lichocka, Jadwiga Szczegielniak, and Grażyna Dobrowolska. "Regulation of ABA-Non-Activated SNF1-Related Protein Kinase 2 Signaling Pathways by Phosphatidic Acid." International Journal of Molecular Sciences 21, no. 14 (July 15, 2020): 4984. http://dx.doi.org/10.3390/ijms21144984.
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Phosphatidic acid (PA) is involved in the regulation of plant growth and development, as well as responses to various environmental stimuli. Several PA targets in plant cells were identified, including two SNF1-related protein kinases 2 (SnRK2s), SnRK2.10 and SnRK2.4, which are not activated by abscisic acid (ABA). Here, we investigated the effects of PA on various elements of ABA-non-activated SnRK2 signaling. PA 16:0/18:1 was found to modulate the SnRK2 structure and the phosphorylation of some SnRK2 targets. Conversely, phosphorylation by the ABA-non-activated SnRK2s, of one of such targets, dehydrin Early Responsive to Dehydration 14 (ERD14), affects its interaction with PA and subcellular localization. Moreover, PA 16:0/18:1 modulates the activity and/or localization of negative regulators of the ABA-non-activated SnRK2s, not only of the ABA insensitive 1 (ABI1) phosphatase, which was identified earlier, but also of another protein phosphatase 2C, PP2CA. The activity of both phosphatases was inhibited by about 50% in the presence of 50 μM PA. PA 16:0/18:1 also impacts the phosphorylation and subcellular localization of SnRK2-interacting calcium sensor, known to inhibit SnRK2 activity in a calcium-dependent manner. Thus, PA was found to regulate ABA-non-activated SnRK2 signaling at several levels: the activity, phosphorylation status and/or localization of SnRK2 cellular partners.
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Norambuena, Andrés, Claudia Metz, Juan E. Jung, Antonia Silva, Carolina Otero, Jorge Cancino, Claudio Retamal, Juan C. Valenzuela, Andrea Soza, and Alfonso González. "Phosphatidic Acid Induces Ligand-independent Epidermal Growth Factor Receptor Endocytic Traffic through PDE4 Activation." Molecular Biology of the Cell 21, no. 16 (August 15, 2010): 2916–29. http://dx.doi.org/10.1091/mbc.e10-02-0167.
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Endocytosis modulates EGFR function by compartmentalizing and attenuating or enhancing its ligand-induced signaling. Here we show that it can also control the cell surface versus intracellular distribution of empty/inactive EGFR. Our previous observation that PKA inhibitors induce EGFR internalization prompted us to test phosphatidic acid (PA) generated by phospholipase D (PLD) as an endogenous down-regulator of PKA activity, which activates rolipram-sensitive type 4 phosphodiesterases (PDE4) that degrade cAMP. We found that inhibition of PA hydrolysis by propranolol, in the absence of ligand, provokes internalization of inactive (neither tyrosine-phosphorylated nor ubiquitinated) EGFR, accompanied by a transient increase in PA levels and PDE4s activity. This EGFR internalization is mimicked by PA micelles and is strongly counteracted by PLD2 silencing, rolipram or forskolin treatment, and PKA overexpression. Accelerated EGFR endocytosis seems to be mediated by clathrin-dependent and -independent pathways, leading to receptor accumulation in juxtanuclear recycling endosomes, also due to a decreased recycling. Internalized EGFR can remain intracellular without degradation for several hours or return rapidly to the cell surface upon discontinuation of the stimulus. This novel regulatory mechanism of EGFR, also novel function of signaling PA, can transmodulate receptor accessibility in response to heterologous stimuli.
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Tanguy, Emeline, Qili Wang, Pierre Coste de Bagneaux, Laetitia Fouillen, Tamou Thahouly, Mohamed-Raafet Ammar, and Nicolas Vitale. "Different species of phosphatidic acid are produced during neuronal growth and neurosecretion." OCL 25, no. 4 (March 30, 2018): D408. http://dx.doi.org/10.1051/ocl/2018024.
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Although originally restricted to their structural role as major constituents of membranes, lipids are now well-defined actors to integrate intracellular or extracellular signals. Accordingly, it has been known for decades that lipids, especially those coming from diet, are important to maintain normal physiological functions and good health. This is especially the case to maintain proper cognitive functions and avoid neuronal degeneration. But besides this empiric knowledge, the exact molecular nature of lipids in cellular signaling, as well as their precise mode of action are only starting to emerge. The recent development of novel pharmacological, molecular, cellular and genetic tools to study lipids in vitro and in vivo has contributed to this improvement in our knowledge. Among these important lipids, phosphatidic acid (PA) plays a unique and central role in a great variety of cellular functions. This article will review the different findings illustrating the involvement of PA generated by phospholipase D (PLD) and diacylglycerol kinases (DGK) in the different steps of neuronal development and neurosecretion. We will also present lipidomic evidences indicating that different species of PA are synthesized during these two key neuronal phenomena.
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Vögtle, F. Nora, Michael Keller, Asli A. Taskin, Susanne E. Horvath, Xue Li Guan, Claudia Prinz, Magdalena Opalińska, et al. "The fusogenic lipid phosphatidic acid promotes the biogenesis of mitochondrial outer membrane protein Ugo1." Journal of Cell Biology 210, no. 6 (September 7, 2015): 951–60. http://dx.doi.org/10.1083/jcb.201506085.
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Import and assembly of mitochondrial proteins depend on a complex interplay of proteinaceous translocation machineries. The role of lipids in this process has been studied only marginally and so far no direct role for a specific lipid in mitochondrial protein biogenesis has been shown. Here we analyzed a potential role of phosphatidic acid (PA) in biogenesis of mitochondrial proteins in Saccharomyces cerevisiae. In vivo remodeling of the mitochondrial lipid composition by lithocholic acid treatment or by ablation of the lipid transport protein Ups1, both leading to an increase of mitochondrial PA levels, specifically stimulated the biogenesis of the outer membrane protein Ugo1, a component of the mitochondrial fusion machinery. We reconstituted the import and assembly pathway of Ugo1 in protein-free liposomes, mimicking the outer membrane phospholipid composition, and found a direct dependency of Ugo1 biogenesis on PA. Thus, PA represents the first lipid that is directly involved in the biogenesis pathway of a mitochondrial membrane protein.
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Fan, Zheng, Lizhi Gao, and Wenxia Wang. "Phosphatidic acid stimulates cardiac KATPchannels like phosphatidylinositols, but with novel gating kinetics." American Journal of Physiology-Cell Physiology 284, no. 1 (January 1, 2003): C94—C102. http://dx.doi.org/10.1152/ajpcell.00255.2002.
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Membrane-bound anionic phospholipids such as phosphatidylinositols have the capacity to modulate ATP-sensitive potassium (KATP) channels through a mechanism involving long-range electrostatic interaction between the lipid headgroup and channel. However, it has not yet been determined whether the multiple effects of phosphatidylinositols reported in the literature all result from this general electrostatic interaction or require a specific headgroup structure. The present study investigated whether phosphatidic acid (PA), an anionic phospholipid substantially different in structure from phosphatidylinositols, evokes effects similar to phosphatidylinositols on native KATP channels of rat heart and heterogeneous Kir6.2/SUR2A channels. Channels treated with PA (0.2–1 mg/ml applied to the cytoplasmic side of the membrane) exhibited higher activity, lower sensitivity to ATP inhibition, less Mg2+-dependent nucleotide stimulation, and poor sulfonylurea inhibition. These effects match the spectrum of phosphatidylinositols' effects, but, in addition, PA also induced a novel pattern in gating kinetics, represented by a decreased mean open time (from 12.2 ± 2.0 to 3.3 ± 0.7 ms). This impact on gating kinetics clearly distinguishes PA's effects from those of phosphatidylinositols. Results indicate that multiple effects of anionic phospholipids on KATP channels are related phenomena and can likely be attributed to a common mechanism, but additional specific effects due to other mechanisms may also coincide.
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Cao, Chunyan, Peipei Wang, Hongdi Song, Wen Jing, Like Shen, Qun Zhang, and Wenhua Zhang. "Corrigendum to: Phosphatidic acid binds to and regulates guanine nucleotide exchange factor 8 (GEF8) activity in Arabidopsis." Functional Plant Biology 48, no. 3 (2021): 359. http://dx.doi.org/10.1071/fp17113_co.
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Phosphatidic acid (PA) forms part of plant lipid metabolism and is a signalling molecule used in response to various external stresses. Guanine nucleotide exchange factors (GEFs) activate small GTPase ROPs, serving as molecular switches in a wide range of signalling pathways. However, the interaction between PA and GEFs in plants has not yet been reported. Here we show that PA bound specifically to GEF8 by using fat-Western blot and isothermal titration calorimetry assays. A C-terminal truncation of GEF8 exhibited strong PA binding, and mutation of lysines 13 and 18 in GEF8 PRONE domain caused a total loss of binding to PA. Two ROPs, ROP7 and ROP10, were identified as preferred substrates of GEF8 by pull-down and bimolecular fluorescence complementation assays. GEF8 activity towards ROP7, but not ROP10, was stimulated by PA both in vitro and in cells. Moreover, the PA- or ABA-induced activation of GEF8 was completely lost in the mutant GEF8, which did not bind to PA. Together, these findings identify a direct interconnection between PA-mediated GEFs activity and small GTPase signalling in plants and provide evidence for a synergistic activation of GEF8 by direct PA-binding to its PRONE domain.
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Gerrard, Jon M., Pauline Robinson, Michael Narvey, and Archibald McNicol. "Increased phosphatidic acid and decreased lysophosphatidic acid in response to thrombin is associated with inhibition of platelet aggregation." Biochemistry and Cell Biology 71, no. 9-10 (September 1, 1993): 432–39. http://dx.doi.org/10.1139/o93-064.
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Thromboxane A2, produced from the arachidonic acid released from platelet phospholipids by phospholipase A2, stimulates platelet aggregation. It remains unresolved whether additional products of platelet phospholipase A2 might promote aggregation. To address this question, we have used aspirin-treated platelets to block thromboxane A2 formation and studied the influence of the phospholipase A2 inhibitor U10029A on platelet aggregation and secretion in response to thrombin. U10029A at 100 μM markedly inhibited platelet aggregation, but had no effect on platelet secretion. Since this concentration of U10029A effectively blocked lysophosphatidic acid (LPA) formation, LPA was added and found to substantially reverse the inhibitory effect of U10029A in these platelets. Furthermore, the action of U10029A was not due to inhibition of phosphatidate phosphohydrolase because U10029A, unlike propranolol, did not inhibit this enzyme. Although it is not possible to conclusively rule out an effect of U10029A in addition to its inhibition of phospholipase A2, our results reveal that a product of phospholipase A2 other than thromboxane A2 is important for platelet aggregation, but not for secretion in response to thrombin. Our data suggest that this product is LPA. Since the amount of phosphatidic acid (PA) increased dramatically concurrent with inhibition of platelet aggregation, it is safe to conclude that PA has no direct role to promote platelet aggregation in response to thrombin.Key words: lysophosphatidic acid, phosphatidic acid, phospholipase A2, human platelet.
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Minegishi, Takashi, and Peter C. K. Leung. "Effects of prostaglandins and luteinizing hormone-releasing hormone on phosphatidic acid – phosphatidylinositol labeling in rat granulosa cells." Canadian Journal of Physiology and Pharmacology 63, no. 4 (April 1, 1985): 320–24. http://dx.doi.org/10.1139/y85-058.
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In cultures of rat granulosa cells, luteinizing hormone-releasing hormone (LHRH) increases 32P incorporation into both phosphatidylinositol (PI) and phosphatidic acid (PA). After 20 min, the level of radioactivity was three- to four-fold (p < 0.01) above control in the PI and PA fractions, respectively. The stimulatory effect of LHRH on 32P incorporation was limited to PI and PA. Similar to the effects of LHRH, a rapid and marked increase of 32P incorporation into both PI and PA is observed upon addition of prostaglandin F2α (PGF2α) (10−5 M) to rat granulosa cells. Incorporation of radioactivity into PA was already increased (p < 0.05) by 2 min following PGF2α addition, while the increase in 32P-labeled PI became significant (p < 0.01) by 5 min. In contrast to PGF2α, the labeling of PI and PA following the addition of PGE2 (10−5 M) was not significantly different from control levels during the entire 10 min of incubation. The sensitivity of the increased PA–PI labeling induced by LHRH and PGF2α is compared in another experiment. After 20 min incubation 10−6 M LHRH increased PI and PA labeling by six-and four-fold, respectively. Although the effect of PGF2α is less than that of LHRH, 10−5 M PGF2α significantly (p < 0.01) increased PI and PA labeling by three- and two-fold, respectively. By contrast, 10−6 M PGE2 failed to affect 32P incorporation into the various phospholipid fractions, but a small enhancement (p < 0.05) of PI and PA labeling was observed only at 10−5 M PGE2. These data further support the hypothesis that LHRH and PGF2α share a common mechanism in ovarian cells involving phospholipid metabolism.
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Mallows, R. S. E., and T. B. Bolton. "Relationship between stimulated phosphatidic acid production and inositol lipid hydrolysis in intestinal longitudinal smooth muscle from guinea pig." Biochemical Journal 244, no. 3 (June 15, 1987): 763–68. http://dx.doi.org/10.1042/bj2440763.
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Accumulation of [32P]phosphatidic acid (PA) and total [3H]inositol phosphates (IPs) was measured in the longitudinal smooth-muscle layer from guinea-pig small intestine. Stimulation with carbachol, histamine and substance P produced increases in accumulation of both [3H]IPs and [32P]PA over the same concentration range. The increase in [32P]PA accumulation in response to carbachol (1 microM-0.1 mM) was inhibited in the presence of atropine (0.5 microM). Buffering the external free [Ca2+] to 10 nM did not prevent the carbachol-stimulated increase in [32P]PA accumulation. Carbachol and Ca2+ appear to act synergistically to increase accumulation of [32P]PA. In contrast, although incubation with noradrenaline also increased accumulation of [3H]IPs, no increase in accumulation of [32P]PA could be detected. These results suggest that an increase in formation of IPs is not necessarily accompanied by an increase in PA formation, and imply the existence of receptor-modulated pathways regulating PA concentrations other than by phospholipase-C-catalysed inositol phospholipid hydrolysis.
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Gao, Hong-Bo, Yu-Jia Chu, and Hong-Wei Xue. "Phosphatidic Acid (PA) Binds PP2AA1 to Regulate PP2A Activity and PIN1 Polar Localization." Molecular Plant 6, no. 5 (September 2013): 1692–702. http://dx.doi.org/10.1093/mp/sst076.
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