MassBank is the first public repository of mass spectra of small chemical compounds for life sciences (<3000 Da). The database contains 605 electron-ionization mass spectrometry (EI-MS), 137 fast atom bombardment MS and 9276 electrospray ionization (ESI)-MS(n) data of 2337 authentic compounds of metabolites, 11 545 EI-MS and 834 other-MS data of 10,286 volatile natural and synthetic compounds, and 3045 ESI-MS(2) data of 679 synthetic drugs contributed by 16 research groups (January 2010). ESI-MS(2) data were analyzed under nonstandardized, independent experimental conditions. MassBank is a distributed database. Each research group provides data from its own MassBank data servers distributed on the Internet. MassBank users can access either all of the MassBank data or a subset of the data by specifying one or more experimental conditions. In a spectral search to retrieve mass spectra similar to a query mass spectrum, the similarity score is calculated by a weighted cosine correlation in which weighting exponents on peak intensity and the mass-to-charge ratio are optimized to the ESI-MS(2) data. MassBank also provides a merged spectrum for each compound prepared by merging the analyzed ESI-MS(2) data on an identical compound under different collision-induced dissociation conditions. Data merging has significantly improved the precision of the identification of a chemical compound by 21-23% at a similarity score of 0.6. Thus, MassBank is useful for the identification of chemical compounds and the publication of experimental data.

Influenza A viruses are a major cause of mortality. Given the potential for future lethal pandemics, effective drugs are needed for the treatment of severe influenza such as that caused by H5N1 viruses. Using mediator lipidomics and bioactive lipid screen, we report that the omega-3 polyunsaturated fatty acid (PUFA)-derived lipid mediator protectin D1 (PD1) markedly attenuated influenza virus replication via RNA export machinery. Production of PD1 was suppressed during severe influenza and PD1 levels inversely correlated with the pathogenicity of H5N1 viruses. Suppression of PD1 was genetically mapped to 12/15-lipoxygenase activity. Importantly, PD1 treatment improved the survival and pathology of severe influenza in mice, even under conditions where known antiviral drugs fail to protect from death. These results identify the endogenous lipid mediator PD1 as an innate suppressor of influenza virus replication that protects against lethal influenza virus infection.

All organisms consist of cells that are enclosed by a cell membrane containing bipolar lipids and proteins. Glycerophospholipids are important not only as structural and functional components of cellular membrane but also as precursors of various lipid mediators. Polyunsaturated fatty acids comprising arachidonic acid or eicosapentaenoic acid are located at sn-2 position, but not at sn-1 position of glycerophospholipids in an asymmetrical manner. In addition to the asymmetry, the membrane diversity is important for membrane fluidity and curvature. To explain the asymmetrical distribution of fatty acids, the rapid turnover of sn-2 position was proposed in 1958 by Lands [Lands WE (1958) Metabolism of glycerolipides: A comparison of lecithin and triglyceride synthesis. J Biol Chem 231:883-888]. However, the molecular mechanisms and biological significance of the asymmetry remained unknown. Here, we describe a putative enzyme superfamily consisting mainly of three gene families, which catalyzes the transfer of acyl-CoAs to lysophospholipids to produce different classes of phospholipids. Among them, we characterized three important enzymes with different substrate specificities and tissue distributions; one, termed lysophosphatidylcholine acyltransferase-3 (a mammalian homologue of Drosophila nessy critical for embryogenesis), prefers arachidonoyl-CoA, and the other two enzymes incorporate oleoyl-CoAs to lysophosphatidylethanolamine and lysophosphatidylserine. Thus, we propose that the membrane diversity is produced by the concerted and overlapped reactions with multiple enzymes that recognize both the polar head group of glycerophospholipids and various acyl-CoAs. Our findings constitute a critical milestone for our understanding about how membrane diversity and asymmetry are established and their biological significance.glycerophospholipids ͉ Lands' cycle ͉ membrane remodeling ͉ phospholipase A 2 ͉ acyl-CoA

Platelet-activating factor (PAF) is a potent proinflammatory lipid mediator eliciting a variety of cellular functions. Lipid mediators, including PAF are produced from membrane phospholipids by enzymatic cascades. Although a G protein-coupled PAF receptor and degradation enzymes have been cloned and characterized, the PAF biosynthetic enzyme, aceyl-CoA:lyso-PAF acetyltransferase, has not been identified. Here, we cloned lyso-PAF acetyltransferase, which is critical in stimulusdependent formation of PAF. The enzyme is a 60-kDa microsomal protein with three putative membrane-spanning domains. The enzyme was induced by bacterial endotoxin (lipopolysaccharide), which was suppressed by dexamethasone treatment. Surprisingly, the enzyme catalyzed not only biosynthesis of PAF from lyso-PAF but also incorporation of arachidonoyl-CoA to produce PAF precursor membrane glycerophospholipids (lysophosphatidylcholine acyltransferase activity). Under resting conditions, the enzyme prefers arachidonoyl-CoA and contributes to membrane biogenesis. Upon acute inflammatory stimulation with lipopolysaccharide, the activated enzyme utilizes acetyl-CoA more efficiently and produces PAF. Thus, our findings provide a novel concept that a single enzyme catalyzes membrane biogenesis of inflammatory cells while producing a prophlogistic mediator in response to external stimuli.Platelet-activating factor (PAF 3 ; 1-O-alkyl-2-acetyl-sn-glycero-3-phosphocholine) is a phospholipid mediator that activates a G protein-coupled receptor (1-3) and results in pleiotropic and potent biological effects, including platelet activation, airway constriction, and hypotension (1). PAF is synthesized in various cells and tissues via two distinct pathways, the de novo and remodeling pathways (2, 4, 5), and the latter is regulated by extracellular signals and plays a critical role in stimulus-coupled PAF biosynthesis (2, 4 -6). PAF synthesis induced by extracellular signals has been reported in murine peritoneal cells stimulated by calcium ionophore (7) or by PAF (8), in human eosinophils stimulated by fMet-Leu-Phe (9), in human neutrophils stimulated by acid stress (10), and in murine peritoneal macrophages stimulated by lipopolysaccharide (LPS) (11). In the remodeling pathway, the precursor of PAF, 1-Oalkyl-sn-glycero-3-phosphocholine (lyso-PAF), is synthesized from 1-O-alkyl-2-arachidonoyl-sn-glycero-3-phosphocholine (1-alkyl-phosphatidylcholine; PC) by the action of phospholipase A 2 (2, 4, 12, 13). Subsequently, lyso-PAF is converted to PAF by acetyl-CoA:lyso-PAF acetyltransferase (lyso-PAF acetyltransferase) (EC 2.3.1.67) (14). PAF is then rapidly degraded to lyso-PAF by PAF acetylhydrolases (15). Alternatively, lyso-PAF is again transformed into PC by the action of lysophosphatidylcholine (LPC) acyltransferase (2.3.1.23) (16).A G protein-coupled PAF receptor was cloned in our laboratory (17), and PAF acetylhydrolases have been cloned and characterized by others (18,19). Lyso-PAF acetyltransferase was initially demonstrated and partially characterized by ...

No abstract

p2y5 is an orphan G protein-coupled receptor that is closely related to the fourth lysophosphatidic acid (LPA) receptor, LPA 4 . Here we report that p2y5 is a novel LPA receptor coupling to the G 13 -Rho signaling pathway. "LPA receptor-null" RH7777 and B103 cells exogenously expressing p2y5 showed [ 3 H]LPA binding, LPA-induced [35 S]guanosine 5-3-O-(thio)triphosphate binding, Rho-dependent alternation of cellular morphology, and G s/13 chimeric protein-mediated cAMP accumulation. LPA-induced contraction of human umbilical vein endothelial cells was suppressed by small interfering RNA knockdown of endogenously expressed p2y5. We also found that 2-acyl-LPA had higher activity to p2y5 than 1-acyl-LPA. A recent study has suggested that p2y5 is an LPA receptor essential for human hair growth. We confirmed that p2y5 is a functional LPA receptor and propose to designate this receptor LPA 6 .Lysophosphatidic acid (LPA 3 ; 1-or 2-acyl-sn-glycero-3-phosphate) is a naturally occurring lipid mediator with diverse biological activities (1, 2). LPA plays important roles in many biological processes, such as the nervous system (3), tumor metastasis (4), wound healing (5), cardiovascular functions (6), and reproduction (7), through its specific G protein-coupled receptors (GPCRs). At least five subtypes of LPA receptors have been identified. Three receptors (LPA 1 (8), LPA 2 (9), and LPA 3 (10, 11)) share about 50% amino acid sequence identities, and form the Edg (endothelial differentiation gene) family together with the GPCRs for sphingosine 1-phosphate. Two additional LPA receptors, p2y9/LPA 4 (12) and GPR92/LPA 5 (13, 14), which show small similarities with the Edg family GPCRs, were recently identified. These LPA receptors, by coupling with different sets of G proteins, transduce various responses in many cell types. Depending on the functional coupling of a given LPA receptor to the G proteins, LPA activates diverse signaling cascades involving phosphoinositide 3-kinase, phospholipase C, mitogen-activated protein kinase, Rho-family GTPase, and adenylyl cyclase (2).The fact that p2y5 shares the highest sequence homology with p2y9/LPA 4 among all GPCRs (12) strongly suggested that LPA is a ligand for p2y5. However, we could not detect LPAinduced Ca 2ϩ mobilization or cAMP level changes in p2y5-overexpressing cells at the time of the identification of p2y9/ LPA 4 as the fourth LPA receptor in our laboratory (12). In the course of the further analysis of p2y5-overexpressing cells, we found that p2y5 actually responded to LPA with activation of the G 13 -Rho signaling pathway. Our results confirm the identification of p2y5 as an LPA receptor and extend the knowledge of the functional roles of LPA. EXPERIMENTAL PROCEDURESLipids-1-Oleoyl-LPA, 1-palmitoyl-LPA, 1-stearoyl-LPA, 1-myristoyl-LPA, and 1-arachidonoyl-LPA were purchased from Avanti Polar Lipids (Alabaster, AL). 1-Linoleoyl-LPA was from Echelon Biosciences (Salt Lake City, UT). These lipids were stored at Ϫ30°C (10 mM stock in 50% ethanol). Alkyl-OMPT (10 mM stock in d...

No abstract

PLA2G2D ameliorates skin inflammation through mobilizing pro-resolving lipid mediators.