Significance Communication between nerve cells occurs at specialized cellular structures known as synapses. Loss of synaptic function is associated with cognitive decline in Alzheimer’s disease (AD). However, the mechanism of synaptic damage remains incompletely understood. Here we describe a pathway for synaptic damage whereby amyloid-β 1–42 peptide (Aβ 1–42 ) releases, via stimulation of α7 nicotinic receptors, excessive amounts of glutamate from astrocytes, in turn activating extrasynaptic NMDA-type glutamate receptors (eNMDARs) to mediate synaptic damage. The Food and Drug Administration-approved drug memantine offers some beneficial effect, but the improved eNMDAR antagonist NitroMemantine completely ameliorates Aβ-induced synaptic loss, providing hope for disease-modifying intervention in AD.

Eicosanoids have been implicated in a vast number of devastating inflammatory conditions, including arthritis, atherosclerosis, pain, and cancer. Currently, over a hundred different eicosanoids have been identified, with many having potent bioactive signaling capacity. These lipid metabolites are synthesized de novo by at least 50 unique enzymes, many of which have been cloned and characterized. Due to the extensive characterization of eicosanoid biosynthetic pathways, this field provides a unique framework for integrating genomics, proteomics, and metabolomics toward the investigation of disease pathology. To facilitate a concerted systems biology approach, this review outlines the proteins implicated in eicosanoid biosynthesis and signaling in human, mouse, and rat. Applications of the extensive genomic and lipidomic research to date illustrate the questions in eicosanoid signaling that could be uniquely addressed by a thorough analysis of the entire eicosanoid proteome.-Buczynski, M. W., D. S. Dumlao, and E. A. Dennis. An integrated omics analysis of eicosanoid biology.

The LIPID MAPS Consortium (www.lipidmaps. org) is developing comprehensive procedures for identifying all lipids of the macrophage, following activation by endotoxin. The goal is to quantify temporal and spatial changes in lipids that occur with cellular metabolism and to develop bioinformatic approaches that establish dynamic lipid networks. To achieve these aims, an endotoxin of the highest possible analytical specification is crucial. We now report a large-scale preparation of 3-deoxy-D-manno-octulosonic acid (Kdo) 2 -Lipid A, a nearly homogeneous Re lipopolysaccharide (LPS) sub-structure with endotoxin activity equal to LPS. Kdo 2 -Lipid A was extracted from 2 kg cell paste of a heptose-deficient Escherichia coli mutant. It was purified by chromatography on silica, DEAE-cellulose, and C18 reverse-phase resin. Structure and purity were evaluated by electrospray ionization/mass spectrometry, liquid chromatography/mass spectrometry and 1 H-NMR. Its bioactivity was compared with LPS in RAW 264.7 cells and bone marrow macrophages from wild-type and toll-like receptor 4 (TLR-4)-deficient mice. Cytokine and eicosanoid production, in conjunction with gene expression profiling, were employed as readouts. Kdo 2 -Lipid A is comparable to LPS by these criteria. Its activity is reduced by . The LIPID MAPS consortium is developing quantitative methods for evaluating the composition, biosynthesis, and function of all macrophage lipids (1). These amphipathic substances not only are structural components of biological membranes but also play important roles in the pathophysiology of inflammation, atherosclerosis, and growth control. Additional lipid functions should emerge from the comprehensive analysis of macrophage lipids. Electrospray ionization/mass spectrometry (ESI/MS) (2, 3), coupled with prefractionation methods like reversephase liquid chromatography (LC), is being applied systematically to set the stage for the seamless integration of lipid metabolism into the broader fields of genomics, proteomics, and systems biology. To facilitate this endeavor, LIPID MAPS has introduced a new comprehensive classification system for biological lipids, amenable to computer-based data processing and substructure comparison (4). The eight LIPID MAPS categories are 1) fatty acyls, 2) glycerolipids, 3) glycerophospholipids, 4) sphingolipids, 5) sterol lipids, 6) prenol lipids, 7) saccharolipids,

The endocannabinoids 2-arachidonoyl glycerol (2-AG) and N-arachidonoyl ethanolamine (anandamide) are principally degraded by monoacylglycerol lipase (MAGL) and fatty acid amide hydrolase (FAAH), respectively. The recent discovery of O-aryl carbamates such as JZL184 as selective MAGL inhibitors has enabled the functional investigation of 2-AG signaling pathways in vivo. Nonetheless, JZL184 and other reported MAGL inhibitors still display low-level cross-reactivity with FAAH and peripheral carboxylesterases, which can complicate their use in certain biological studies. Here, we report a distinct class of O-hexafluoroisopropyl (HFIP) carbamates that inhibit MAGL in vitro and in vivo with excellent potency and greatly improved selectivity, including showing no detectable cross-reactivity with FAAH. These findings designate HFIP-carbamates as a versatile chemotype for inhibiting MAGL and should encourage the pursuit of other serine hydrolase inhibitors that bear reactive groups resembling the structures of natural substrates.

Eicosanoids constitute a large class of biologically active arachidonic acid (AA) metabolites that play important roles in numerous physiological processes. Eicosanoids are produced by several distinct routes, including the cyclooxygenase, lipoxygenase, and P450 enzymatic pathways, as well as by nonenzymatic processes. In order to completely understand the eicosanoid response of a cell or tissue to a given stimulus, measuring the complete profile of eicosanoids produced is important. Since the eicosanoids are products of a single species, AA, and represent, for the most part, the addition of various oxygen species, the hundreds of eicosanoids have very similar structures, chemistries, and physical properties. The identification and quantitation of all eicosanoids in a single biological sample are a challenging task, one that high-performance liquid chromatography-mass spectrometry (LC-MS) is well suited to handle. We have developed a LC-MS/MS procedure for isolating, identifying, and quantitating a broad spectrum of eicosanoids in a single biological sample. We currently can measure over 60 eicosanoids in a 16-min LC-MS/MS analysis. Our method employs stable isotope dilution internal standards to quantitate these specific eicosanoids. In the course of setting up the LC-MS system, we have established a library that includes relative chromatographic retention times and tandem mass spectrometry data for the most common eicosanoids. This library is available to the scientific community on the website www.lipidmaps.org.