MedWorm.com provides a medical RSS filtering service. Over 6000 RSS medical sources are combined and output via different filters. This feed contains the latest items from the 'The Journal of Lipid Research' source. Tue, 07 Feb 2012 05:19:55 +0100 http://www.medworm.com/index.php?rid=5578294&cid=s_32073_162_f&fid=32073&url=http%3A%2F%2Fwww.jlr.org%2Fcgi%2Fcontent%2Fshort%2F53%2F2%2F325%3Frss%3D1 In this study, we developed a new fluorometric method for measuring PS using combinations of specific enzymes and Amplex Red. The calibration curve for PS measurement was linear and hyperbolic at low (0–50 µM) and high (50–1000 µM) concentrations, respectively, and the detection limit was 5 µM (50 pmol in the reaction mixture). This assay quantified PS regardless of the chain length and the number of double bonds. We applied this new method to the determination of PS content in HEK293 cells, which was validated by a recovery study and comparison with TLC-phosphorus assay. We showed that the PS content was high in sparse cells. The overexpression of PS synthase 1 elevated not only the cellular PS content but also the phosphatidylcholine (PC) and phosphatidyleth... The Journal of Lipid Research journals http://www.medworm.com/rss/comments.php?id=5578294 Mon, 09 Jan 2012 05:00:00 +0100 5578294 http://www.medworm.com/index.php?rid=5578293&cid=s_32073_162_f&fid=32073&url=http%3A%2F%2Fwww.jlr.org%2Fcgi%2Fcontent%2Fshort%2F53%2F2%2F321%3Frss%3D1 Insulin resistance in adipose tissue increases the release of free fatty acids into the circulation, which likely contributes to impaired insulin action in liver and skeletal muscle associated with obesity. However, reliable assessment of adipose tissue insulin resistance requires performing a hyperinsulinemic-euglycemic clamp procedure in conjunction with a fatty acid tracer infusion to determine insulin-mediated suppression of lipolytic rate. We developed a simpler method for evaluating adipose tissue insulin resistance in vivo, determined as the product of palmitate rate of appearance into the bloodstream and plasma insulin concentration during basal conditions. We validated our Adipose Tissue Insulin Resistance Index (ATIRI) by comparison with an assessment of adipose tissue insulin re... The Journal of Lipid Research journals http://www.medworm.com/rss/comments.php?id=5578293 Mon, 09 Jan 2012 05:00:00 +0100 5578293 http://www.medworm.com/index.php?rid=5578292&cid=s_32073_162_f&fid=32073&url=http%3A%2F%2Fwww.jlr.org%2Fcgi%2Fcontent%2Fshort%2F53%2F2%2F311%3Frss%3D1 Sterol 14α-demethylase (CYP51) that catalyzes the removal of the 14α-methyl group from the sterol nucleus is an essential enzyme in sterol biosynthesis, a primary target for clinical and agricultural antifungal azoles and an emerging target for antitrypanosomal chemotherapy. Here, we present the crystal structure of Trypanosoma (T) brucei CYP51 in complex with the substrate analog 14α-methylenecyclopropyl-7-24,25-dihydrolanosterol (MCP). This sterol binds tightly to all protozoan CYP51s and acts as a competitive inhibitor of F105-containing (plant-like) T. brucei and Leishmania (L) infantum orthologs, but it has a much stronger, mechanism-based inhibitory effect on I105-containing (animal/fungi-like) T. cruzi CYP51. Depicting substrate orientation in the conserved CYP51 b... The Journal of Lipid Research journals http://www.medworm.com/rss/comments.php?id=5578292 Mon, 09 Jan 2012 05:00:00 +0100 5578292 http://www.medworm.com/index.php?rid=5578291&cid=s_32073_162_f&fid=32073&url=http%3A%2F%2Fwww.jlr.org%2Fcgi%2Fcontent%2Fshort%2F53%2F2%2F300%3Frss%3D1 Diabetic peripheral neuropathy (DPN) is characterized by myelin abnormalities; however, the molecular mechanisms underlying such deficits remain obscure. To uncover the effects of diabetes on myelin alterations, we have analyzed myelin composition. In a streptozotocin-treated rat model of diabetic neuropathy, analysis of sciatic nerve myelin lipids revealed that diabetes alters myelin's phospholipid, FA, and cholesterol content in a pattern that can modify membrane fluidity. Reduced expression of relevant genes in the FA biosynthetic pathway and decreased levels of the transcriptionally active form of the lipogenic factor sterol-regulatory element binding factor-1c (SREBF-1c) were found in diabetic sciatic nerve. Expression of myelin's major protein, myelin protein zero (P0), was also supp... The Journal of Lipid Research journals http://www.medworm.com/rss/comments.php?id=5578291 Mon, 09 Jan 2012 05:00:00 +0100 5578291 http://www.medworm.com/index.php?rid=5578290&cid=s_32073_162_f&fid=32073&url=http%3A%2F%2Fwww.jlr.org%2Fcgi%2Fcontent%2Fshort%2F53%2F2%2F292%3Frss%3D1 Conversion of fatty acid hydroperoxides to epoxyalcohols is a well known secondary reaction of lipoxygenases, described for S-specific lipoxygenases forming epoxyalcohols with a trans-epoxide configuration. Here we report on R-specific lipoxygenase synthesis of a cis-epoxyalcohol. Although arachidonic and dihomo--linolenic acids are metabolized by extracts of the Caribbean coral Plexaura homomalla via 8R-lipoxygenase and allene oxide synthase activities, 20:36 forms an additional prominent product, identified using UV, GC-MS, and NMR in comparison to synthetic standards as 8R,9S-cis-epoxy-10S-erythro-hydroxy-eicosa-11Z,14Z-dienoic acid. Both oxygens of 18O-labeled 8R-hydroperoxide are retained in the product, indicating a hydroperoxide isomerase activity. Recombinant allene oxide synthase ... The Journal of Lipid Research journals http://www.medworm.com/rss/comments.php?id=5578290 Mon, 09 Jan 2012 05:00:00 +0100 5578290 http://www.medworm.com/index.php?rid=5578289&cid=s_32073_162_f&fid=32073&url=http%3A%2F%2Fwww.jlr.org%2Fcgi%2Fcontent%2Fshort%2F53%2F2%2F282%3Frss%3D1 Synthesis inhibition is the basis for the treatment of type 1 Gaucher disease by the glucosylceramide synthase (GCS) inhibitor eliglustat tartrate. However, the extended use of eliglustat and related compounds for the treatment of glycosphingolipid storage diseases with CNS manifestations is limited by the lack of brain penetration of this drug. Property modeling around the D-threo-1-phenyl-2-decanoylamino-3-morpholino-propanol (PDMP) pharmacophore was employed in a search for compounds of comparable activity against the GCS but lacking P-glycoprotein (MDR1) recognition. Modifications of the carboxamide N-acyl group were made to lower total polar surface area and rotatable bond number. Compounds were screened for inhibition of GCS in crude enzyme and whole cell assays and for MDR1 substrat... The Journal of Lipid Research journals http://www.medworm.com/rss/comments.php?id=5578289 Mon, 09 Jan 2012 05:00:00 +0100 5578289 http://www.medworm.com/index.php?rid=5578288&cid=s_32073_162_f&fid=32073&url=http%3A%2F%2Fwww.jlr.org%2Fcgi%2Fcontent%2Fshort%2F53%2F2%2F273%3Frss%3D1 Peroxisome proliferator-activated receptor gamma coactivator-1α (PGC-1α), a key regulator of energy metabolism and lipid homeostasis in multiple highly oxidative tissues, has been implicated in the metabolic derangements of diabetes and obesity. However, relatively less is known regarding its role in neurological functions. Using shotgun lipidomics, we investigated the lipidome of mouse cerebral cortex with generalized deficiency of PGC-1α (PGC-1α–/–) versus wild-type (WT) mice under standard diet and chronically calorically restricted conditions. Specific deficiency in sulfatide, a myelin-specific lipid class critically involved in maintaining neurological function, was uncovered in the cortex of PGC-1α–/– mice compared with WT mice at... The Journal of Lipid Research journals http://www.medworm.com/rss/comments.php?id=5578288 Mon, 09 Jan 2012 05:00:00 +0100 5578288 http://www.medworm.com/index.php?rid=5578287&cid=s_32073_162_f&fid=32073&url=http%3A%2F%2Fwww.jlr.org%2Fcgi%2Fcontent%2Fshort%2F53%2F2%2F266%3Frss%3D1 To assess the relationships of lipoprotein mass concentrations to all-cause and coronary heart disease (CHD) mortality, we analyzed the prospective 53-year follow-up of 1,905 men measured for lipoprotein mass concentrations by analytic ultracentrifugation between 1954 and 1957. Cause of death was determined from medical records and death certificates before 1979 and from National Death Index death diagnoses thereafter. Of the 1,329 men (69.8%) who died through 2008, CHD was listed as a contributing cause of death for 409 men, including 113 deaths from premature CHD (age ≤ 65 years). When adjusted for age, the risk associated with the lowest HDL2 quartile increased 22% for all-cause (P = 0.001), 63% for total CHD (P < 10–5), and 117% for premature CHD mortality (P = 0.0001). Whe... The Journal of Lipid Research journals http://www.medworm.com/rss/comments.php?id=5578287 Mon, 09 Jan 2012 05:00:00 +0100 5578287 http://www.medworm.com/index.php?rid=5578286&cid=s_32073_162_f&fid=32073&url=http%3A%2F%2Fwww.jlr.org%2Fcgi%2Fcontent%2Fshort%2F53%2F2%2F257%3Frss%3D1 This study investigates this mechanism by measuring the effect of exogenous DHA and eicosapentaenoate (EPA) supplementation on fatty acid composition and metabolism, as well as on metabolic enzyme expression, in a cell culture model of CF. We found that both DHA and EPA suppress the expression and activity of 5- and 6-desaturases, leading to decreased flux through the n-3 and n-6 PUFA metabolic pathways and decreased production of AA. The findings also uncover other metabolic abnormalities, including increased fatty acid uptake and markedly increased retroconversion of DHA to EPA, in CF cells. These results indicate that the fatty acid abnormalities of CF are related to intrinsic alterations of PUFA metabolism and that they may be reversed by supplementation with DHA and EPA. (Source: The ... The Journal of Lipid Research journals http://www.medworm.com/rss/comments.php?id=5578286 Mon, 09 Jan 2012 05:00:00 +0100 5578286 http://www.medworm.com/index.php?rid=5578285&cid=s_32073_162_f&fid=32073&url=http%3A%2F%2Fwww.jlr.org%2Fcgi%2Fcontent%2Fshort%2F53%2F2%2F247%3Frss%3D1 Primary fatty acid amides (PFAM) are important signaling molecules in the mammalian nervous system, binding to many drug receptors and demonstrating control over sleep, locomotion, angiogenesis, and many other processes. Oleamide is the best-studied of the primary fatty acid amides, whereas the other known PFAMs are significantly less studied. Herein, quantitative assays were used to examine the endogenous amounts of a panel of PFAMs, as well as the amounts produced after incubation of mouse neuroblastoma N18TG2 and sheep choroid plexus (SCP) cells with the corresponding fatty acids or N-tridecanoylethanolamine. Although five endogenous primary amides were discovered in the N18TG2 and SCP cells, a different pattern of relative amounts were found between the two cell lines. Higher amounts o... The Journal of Lipid Research journals http://www.medworm.com/rss/comments.php?id=5578285 Mon, 09 Jan 2012 05:00:00 +0100 5578285 http://www.medworm.com/index.php?rid=5578284&cid=s_32073_162_f&fid=32073&url=http%3A%2F%2Fwww.jlr.org%2Fcgi%2Fcontent%2Fshort%2F53%2F2%2F227%3Frss%3D1 White adipose tissue (WAT) is perhaps the most plastic organ in the body, capable of regeneration following surgical removal and massive expansion or contraction in response to altered energy balance. Research conducted for over 70 years has investigated adipose tissue plasticity on a cellular level, spurred on by the increasing burden that obesity and associated diseases are placing on public health globally. This work has identified committed preadipocytes in the stromal vascular fraction of adipose tissue and led to our current understanding that adipogenesis is important not only for WAT expansion, but also for maintenance of adipocyte numbers under normal metabolic states. At the turn of the millenium, studies investigating preadipocyte differentiation collided with developments in st... The Journal of Lipid Research journals http://www.medworm.com/rss/comments.php?id=5578284 Mon, 09 Jan 2012 05:00:00 +0100 5578284 http://www.medworm.com/index.php?rid=5578283&cid=s_32073_162_f&fid=32073&url=http%3A%2F%2Fwww.jlr.org%2Fcgi%2Fcontent%2Fshort%2F53%2F2%2F215%3Frss%3D1 The compartmentation of neutral lipids in plants is mostly associated with seed tissues, where triacylglycerols (TAGs) stored within lipid droplets (LDs) serve as an essential physiological energy and carbon reserve during postgerminative growth. However, some nonseed tissues, such as leaves, flowers and fruits, also synthesize and store TAGs, yet relatively little is known about the formation or function of LDs in these tissues. Characterization of LD-associated proteins, such as oleosins, caleosins, and sterol dehydrogenases (steroleosins), has revealed surprising features of LD function in plants, including stress responses, hormone signaling pathways, and various aspects of plant growth and development. Although oleosin and caleosin proteins are specific to plants, LD-associated sterol... The Journal of Lipid Research journals http://www.medworm.com/rss/comments.php?id=5578283 Mon, 09 Jan 2012 05:00:00 +0100 5578283 http://www.medworm.com/index.php?rid=5513526&cid=s_32073_162_f&fid=32073&url=http%3A%2F%2Fwww.jlr.org%2Fcgi%2Fcontent%2Fshort%2F53%2F1%2F204%3Frss%3D1 The interpretation of the electron ionization mass spectra of straight-chain and methyl-branched saturated and unsaturated wax esters (WEs) is discussed in this study based on the spectra of 154 standards. The most important fragments indicative of the structure of the acid and alcohol chains are identified and summarized for WEs with various number of double bonds in the chains. Briefly, most WEs provide acylium ions allowing structural characterization of the acid part, whereas the alcohol part gives corresponding alkyl radical cations. The elemental composition of selected important fragments is established from a high-resolution accurate mass analysis. The ion abundances are discussed with respect to the length and unsaturation of the aliphatic chains. The interpretation of the spectra... The Journal of Lipid Research journals http://www.medworm.com/rss/comments.php?id=5513526 Thu, 15 Dec 2011 05:00:00 +0100 5513526 http://www.medworm.com/index.php?rid=5513525&cid=s_32073_162_f&fid=32073&url=http%3A%2F%2Fwww.jlr.org%2Fcgi%2Fcontent%2Fshort%2F53%2F1%2F195%3Frss%3D1 Saturated branched chain fatty acids (BCFA) are present as complex mixtures in numerous biological samples. The traditional method for structure elucidation, electron ionization (EI) mass spectrometry, sometimes does not unambiguously enable assignment of branching in isomeric BCFA. Zirrolli and Murphy (Zirrolli , J. A. , and R. A. Murphy. 1993. Low-energy tandem mass spectrometry of the molecular ion derived from fatty acid methyl esters: a novel method for analysis of branched-chain fatty acids. J. Am. Soc. Mass Spectrom. 4: 223–229.) showed that the molecular ions of four BCFA methyl ester (BCFAME) yield highly characteristic fragments upon collisional dissociation using a triple quadrupole instrument. Here, we confirm and extend these results by analysis using a tabletop 3-D ion ... The Journal of Lipid Research journals http://www.medworm.com/rss/comments.php?id=5513525 Thu, 15 Dec 2011 05:00:00 +0100 5513525 http://www.medworm.com/index.php?rid=5513524&cid=s_32073_162_f&fid=32073&url=http%3A%2F%2Fwww.jlr.org%2Fcgi%2Fcontent%2Fshort%2F53%2F1%2F185%3Frss%3D1 In the present study, we propose a continuous assay for the screening of sn-2 lipases by using triacylglycerols (TAGs) from Aleurites fordii seed (tung oil) and a synthetic TAG containing the α-eleostearic acid at the sn-2 position and the oleic acid (OA) at the sn-1 and sn-3 positions [1,3-O-dioleoyl-2-O-α-eleostearoyl-sn-glycerol (sn-OEO)]. Each TAG was coated into a microplate well, and the lipase activity was measured by optical density increase at 272 nm due to transition of α-eleostearic acid from the adsorbed to the soluble state. The sn-1,3-regioselective lipases human pancreatic lipase (HPL), LIP2 lipase from Yarrowia lipolytica (YLLIP2), and a known sn-2 lipase, Candida antarctica lipase A (CALA) were used to validate this method. TLC analysis of lipolysis produ... The Journal of Lipid Research journals http://www.medworm.com/rss/comments.php?id=5513524 Thu, 15 Dec 2011 05:00:00 +0100 5513524 http://www.medworm.com/index.php?rid=5513523&cid=s_32073_162_f&fid=32073&url=http%3A%2F%2Fwww.jlr.org%2Fcgi%2Fcontent%2Fshort%2F53%2F1%2F175%3Frss%3D1 The objective of this study was to test the association of CPT1A variants with body composition and lipids, mediated by consumption of polyunsaturated fatty acids (PUFA). Obesity phenotypes and fasting lipids were measured in a cross-sectional sample of Yup'ik Eskimo individuals (n = 1141) from the Center of Alaska Native Health Research (CANHR) study. Twenty-eight tagging CPT1A SNPs were evaluated with outcomes of interest in regression models accounting for family structure. Several CPT1A polymorphisms were associated with HDL-cholesterol and obesity phenotypes. The P479L (rs80356779) variant was associated with all obesity-related traits and fasting HDL-cholesterol. Interestingly, the association of P479L with HDL-cholesterol was still significant after correcting for body mass index (B... The Journal of Lipid Research journals http://www.medworm.com/rss/comments.php?id=5513523 Thu, 15 Dec 2011 05:00:00 +0100 5513523 http://www.medworm.com/index.php?rid=5513522&cid=s_32073_162_f&fid=32073&url=http%3A%2F%2Fwww.jlr.org%2Fcgi%2Fcontent%2Fshort%2F53%2F1%2F168%3Frss%3D1 This study reports for the first time an important increase in serum PON3 concentrations in HIV-infected patients that is associated with their oxidative status and their treatment with NNRTI. Long-term, prospective studies are needed to confirm the possible influence of this enzyme on the course of this disease and its possible utility as an analytical biomarker. (Source: The Journal of Lipid Research) The Journal of Lipid Research journals http://www.medworm.com/rss/comments.php?id=5513522 Thu, 15 Dec 2011 05:00:00 +0100 5513522 http://www.medworm.com/index.php?rid=5513521&cid=s_32073_162_f&fid=32073&url=http%3A%2F%2Fwww.jlr.org%2Fcgi%2Fcontent%2Fshort%2F53%2F1%2F158%3Frss%3D1 The role of endothelial ABCA1 expression in reverse cholesterol transport (RCT) was examined in transgenic mice, using the endothelial-specific Tie2 promoter. Human ABCA1 (hABCA1) was significantly expressed in endothelial cells (EC) of most tissues except the liver. Increased expression of ABCA1 was not observed in resident peritoneal macrophages. ApoA-I-mediated cholesterol efflux from aortic EC was 2.6-fold higher (P < 0.0001) for cells from transgenic versus control mice. On normal chow diet, Tie2 hABCA1 transgenic mice had a 25% (P < 0.0001) increase in HDL-cholesterol (HDL-C) and more than a 2-fold increase of eNOS mRNA in the aorta (P < 0.04). After 6 months on a high-fat, high-cholesterol (HFHC) diet, transgenic mice compared with controls had a 40% increase in plasma HDL-... The Journal of Lipid Research journals http://www.medworm.com/rss/comments.php?id=5513521 Thu, 15 Dec 2011 05:00:00 +0100 5513521 http://www.medworm.com/index.php?rid=5513520&cid=s_32073_162_f&fid=32073&url=http%3A%2F%2Fwww.jlr.org%2Fcgi%2Fcontent%2Fshort%2F53%2F1%2F149%3Frss%3D1 Choline kinase catalyzes the phosphorylation of choline, the first step of phospholipid synthesis. Increased phosphorylation of choline is a hallmark characteristic of the malignant phenotype in a variety of neoplasms. However, in hypoxic cancer cells, choline phosphorylation is decreased. To understand the mechanism behind this altered metabolic state, we examined the expression and regulation of the major choline kinase isoform, choline kinase α (ChKα), in hypoxic PC-3 human prostate cancer cells. Hypoxia decreased choline phosphorylation, choline kinase activity, and ChKα mRNA and protein levels. Promoter analysis studies revealed a region upstream of the ChKα gene bearing a conserved DNA consensus binding motif, hypoxia response element-7 (HRE7), at position &nd... The Journal of Lipid Research journals http://www.medworm.com/rss/comments.php?id=5513520 Thu, 15 Dec 2011 05:00:00 +0100 5513520 http://www.medworm.com/index.php?rid=5513519&cid=s_32073_162_f&fid=32073&url=http%3A%2F%2Fwww.jlr.org%2Fcgi%2Fcontent%2Fshort%2F53%2F1%2F137%3Frss%3D1 Recent studies indicate that membrane cholesterol can associate with G protein-coupled receptors (GPCRs) and affect their function. Previously, we reported that manipulation of membrane cholesterol affects ligand binding and signal transduction of the type 1 cholecystokinin receptor (CCK1R), a Class A GPCR. We now demonstrate that the closely related type 2 cholecystokinin receptor (CCK2R) does not share this cholesterol sensitivity. The sequences of both receptors reveal almost identical cholesterol interaction motifs in analogous locations in transmembrane segments two, three, four, and five. The disparity in cholesterol sensitivity between these receptors, despite their close structural relationship, provides a unique opportunity to define the possible structural basis of cholesterol se... The Journal of Lipid Research journals http://www.medworm.com/rss/comments.php?id=5513519 Thu, 15 Dec 2011 05:00:00 +0100 5513519 http://www.medworm.com/index.php?rid=5513518&cid=s_32073_162_f&fid=32073&url=http%3A%2F%2Fwww.jlr.org%2Fcgi%2Fcontent%2Fshort%2F53%2F1%2F126%3Frss%3D1 In this study, the role of the two nucleotide-binding domains (NBD) of ABCA1 in apoA-I binding was determined by inserting a TEV protease recognition sequence in the linker region of ABCA1. Analyses of ATP binding and occlusion to wild-type ABCA1 and various NBD mutants revealed that ATP binds equally to both NBDs and is hydrolyzed at both NBDs. The interaction with apoA-I and the apoA-I-dependent cholesterol efflux required not only ATP binding but also hydrolysis in both NBDs. NBD mutations and cellular ATP depletion decreased the accessibility of antibodies to a hemagglutinin (HA) epitope that was inserted at position 443 in the extracellular domain (ECD), suggesting that the conformation of ECDs is altered by ATP hydrolysis at both NBDs. These results suggest that ATP hydrolysis at bot... The Journal of Lipid Research journals http://www.medworm.com/rss/comments.php?id=5513518 Thu, 15 Dec 2011 05:00:00 +0100 5513518 http://www.medworm.com/index.php?rid=5513517&cid=s_32073_162_f&fid=32073&url=http%3A%2F%2Fwww.jlr.org%2Fcgi%2Fcontent%2Fshort%2F53%2F1%2F119%3Frss%3D1 Our goal was to assess the validity of the enrichments of plasma free palmitate and intramuscular (IM) fatty acid metabolites as precursors for calculating the IM triglyceride fractional synthetic rate. We infused U-13C16-palmitate in anesthetized rabbits for 3 h and sampled adductor muscle of legs using both freeze-cut and cut-freeze approaches. We found that IM free palmitate enrichment (0.70 ± 0.07%) was lower (P < 0.0001) than IM palmitoyl-CoA enrichment (2.13 ± 0.17%) in samples taken by the freeze-cut approach. The latter was close (P = 0.33) to IM palmitoyl-carnitine enrichment (2.42 ± 0.16%). The same results were obtained from the muscle samples taken by the cut-freeze approach, except the enrichment of palmitoyl-CoA (2.21 ± 0.08%) was lower (P = 0.0... The Journal of Lipid Research journals http://www.medworm.com/rss/comments.php?id=5513517 Thu, 15 Dec 2011 05:00:00 +0100 5513517 http://www.medworm.com/index.php?rid=5513516&cid=s_32073_162_f&fid=32073&url=http%3A%2F%2Fwww.jlr.org%2Fcgi%2Fcontent%2Fshort%2F53%2F1%2F105%3Frss%3D1 Lipin-1 is the major phosphatidate phosphatase (PAP) in the heart and a transcriptional coactivator that regulates fatty acid (FA) oxidation in the liver. As the control of FA metabolism is essential for maintaining cardiac function, we investigated whether lipin-1 deficiency affects cardiac metabolism and performance. Cardiac PAP activity in lipin-1 deficient [fatty liver dystrophy (fld)] mice was decreased by >80% compared with controls. Surprisingly, oleate oxidation and incorporation in triacylglycerol (TG), as well as glucose oxidation, were not significantly different in perfused working fld hearts. Despite this, [3H]oleate accumulation in phosphatidate and phosphatidylinositol was increased in fld hearts, reflecting the decreased PAP activity. Phosphatidate accumulation was linke... The Journal of Lipid Research journals http://www.medworm.com/rss/comments.php?id=5513516 Thu, 15 Dec 2011 05:00:00 +0100 5513516 http://www.medworm.com/index.php?rid=5513515&cid=s_32073_162_f&fid=32073&url=http%3A%2F%2Fwww.jlr.org%2Fcgi%2Fcontent%2Fshort%2F53%2F1%2F95%3Frss%3D1 The hypothesis tested in this study was that cholesterol esterification by ACAT2 would increase cholesterol absorption efficiency by providing cholesteryl ester (CE) for incorporation into chylomicrons. The assumption was that absorption would be proportional to Acat2 gene dosage. Male ACAT2+/+, ACAT2+/–, and ACAT2–/– mice were fed a diet containing 20% of energy as palm oil with 0.2% (w/w) cholesterol. Cholesterol absorption efficiency was measured by fecal dual-isotope and thoracic lymph duct cannulation (TLDC) methods using [3H]sitosterol and [14C]cholesterol tracers. Excellent agreement among individual mice was found for cholesterol absorption measured by both techniques. Cholesterol absorption efficiency in ACAT2–/– mice was 16% compared with 46–47... The Journal of Lipid Research journals http://www.medworm.com/rss/comments.php?id=5513515 Thu, 15 Dec 2011 05:00:00 +0100 5513515 http://www.medworm.com/index.php?rid=5513514&cid=s_32073_162_f&fid=32073&url=http%3A%2F%2Fwww.jlr.org%2Fcgi%2Fcontent%2Fshort%2F53%2F1%2F87%3Frss%3D1 Biosynthesis of 5,15-dihydroxyeicosatetraenoic acid (5,15-diHETE) in leukocytes involves consecutive oxygenation of arachidonic acid by 5-lipoxygenase (LOX) and 15-LOX in either order. Here, we analyzed the contribution of cyclooxygenase (COX)-2 to the biosynthesis of 5,15-diHETE and 5,11-diHETE in isolated human leukocytes activated with lipopolysaccharide and calcium ionophore A23187. Transformation of arachidonic acid was initiated by 5-LOX providing 5S-HETE as a substrate for COX-2 forming 5S,15S-diHETE, 5S,15R-diHETE, and 5S,11R-diHETE as shown by LC/MS and chiral phase HPLC analyses. The levels of 5,15-diHETE were 0.45 ± 0.2 ng/106 cells (mean ± SEM, n = 6), reaching about half the level of LTB4 (1.3 ± 0.5 ng/106 cells, n = 6). The COX-2 specific inhibitor NS-398... The Journal of Lipid Research journals http://www.medworm.com/rss/comments.php?id=5513514 Thu, 15 Dec 2011 05:00:00 +0100 5513514 http://www.medworm.com/index.php?rid=5513513&cid=s_32073_162_f&fid=32073&url=http%3A%2F%2Fwww.jlr.org%2Fcgi%2Fcontent%2Fshort%2F53%2F1%2F77%3Frss%3D1 Protein farnesyltransferase (FTase) and protein geranylgeranyltransferase-I (GGTase-I) add 15- or 20-carbon lipids, respectively, to proteins that terminate with a CaaX motif. These posttranslational modifications of proteins with lipids promote protein interactions with membrane surfaces in cells, but the in vivo importance of the CaaX prenyltransferases and the protein lipidation reactions they catalyze remain incompletely defined. One study concluded that a deficiency of FTase was inconsequential in adult mice and led to little or no tissue pathology. To assess the physiologic importance of the CaaX prenyltransferases, we used conditional knockout alleles and an albumin–Cre transgene to produce mice lacking FTase, GGTase-I, or both enzymes in hepatocytes. The hepatocyte-specific F... The Journal of Lipid Research journals http://www.medworm.com/rss/comments.php?id=5513513 Thu, 15 Dec 2011 05:00:00 +0100 5513513 http://www.medworm.com/index.php?rid=5513512&cid=s_32073_162_f&fid=32073&url=http%3A%2F%2Fwww.jlr.org%2Fcgi%2Fcontent%2Fshort%2F53%2F1%2F66%3Frss%3D1 The human bile acid pool composition is composed of both primary bile acids (cholic acid and chenodeoxycholic acid) and secondary bile acids (deoxycholic acid and lithocholic acid). Secondary bile acids are formed by the 7α-dehydroxylation of primary bile acids carried out by intestinal anaerobic bacteria. We have previously described a multistep biochemical pathway in Clostridium scindens that is responsible for bile acid 7α-dehydroxylation. We have identified a large (12 kb) bile acid inducible (bai) operon in this bacterium that encodes eight genes involved in bile acid 7α-dehydroxylation. However, the function of the baiF gene product in this operon has not been elucidated. In the current study, we cloned and expressed the baiF gene in E. coli and discovered it has bi... The Journal of Lipid Research journals http://www.medworm.com/rss/comments.php?id=5513512 Thu, 15 Dec 2011 05:00:00 +0100 5513512 http://www.medworm.com/index.php?rid=5513511&cid=s_32073_162_f&fid=32073&url=http%3A%2F%2Fwww.jlr.org%2Fcgi%2Fcontent%2Fshort%2F53%2F1%2F51%3Frss%3D1 In an attempt to understand the applicability of various animal models to dyslipidemia in humans and to identify improved preclinical models for target discovery and validation for dyslipidemia, we measured comprehensive plasma lipid profiles in 24 models. These included five mouse strains, six other nonprimate species, and four nonhuman primate (NHP) species, and both healthy animals and animals with metabolic disorders. Dyslipidemic humans were assessed by the same measures. Plasma lipoprotein profiles, eight major plasma lipid fractions, and FA compositions within these lipid fractions were compared both qualitatively and quantitatively across the species. Given the importance of statins in decreasing plasma low-density lipoprotein cholesterol for treatment of dyslipidemia in humans, th... The Journal of Lipid Research journals http://www.medworm.com/rss/comments.php?id=5513511 Thu, 15 Dec 2011 05:00:00 +0100 5513511 http://www.medworm.com/index.php?rid=5513510&cid=s_32073_162_f&fid=32073&url=http%3A%2F%2Fwww.jlr.org%2Fcgi%2Fcontent%2Fshort%2F53%2F1%2F43%3Frss%3D1 Sequence homology indicates the existence of three human cytosolic acyl protein thioesterases, including APT1 that is known to depalmitoylate H- and N-Ras. One of them is the lysophospholipase-like 1 (LYPLAL1) protein that on the one hand is predicted to be closely related to APT1 but on the other hand might also function as a potential triacylglycerol lipase involved in obesity. However, its role remained unclear. The 1.7 Å crystal structure of LYPLAL1 reveals a fold very similar to APT1, as expected, but features a shape of the active site that precludes binding of long-chain substrates. Biochemical data demonstrate that LYPLAL1 exhibits neither phospholipase nor triacylglycerol lipase activity, but rather accepts short-chain substrates. Furthermore, extensive screening efforts usi... The Journal of Lipid Research journals http://www.medworm.com/rss/comments.php?id=5513510 Thu, 15 Dec 2011 05:00:00 +0100 5513510 http://www.medworm.com/index.php?rid=5513509&cid=s_32073_162_f&fid=32073&url=http%3A%2F%2Fwww.jlr.org%2Fcgi%2Fcontent%2Fshort%2F53%2F1%2F34%3Frss%3D1 Accumulation of cholesterol by macrophage uptake of LDL is a key event in the formation of atherosclerotic plaques. Previous research has shown that granulocyte-macrophage colony-stimulating factor (GM-CSF) is present in atherosclerotic plaques and promotes aortic lipid accumulation. However, it has not been determined whether murine GM-CSF-differentiated macrophages take up LDL to become foam cells. GM-CSF-differentiated macrophages from LDL receptor-null mice were incubated with LDL, resulting in massive macrophage cholesterol accumulation. Incubation of LDL receptor-null or wild-type macrophages with increasing concentrations of 125I-LDL showed nonsaturable macrophage LDL uptake that was linearly related to the amount of LDL added, indicating that LDL uptake was mediated by fluid-phase ... The Journal of Lipid Research journals http://www.medworm.com/rss/comments.php?id=5513509 Thu, 15 Dec 2011 05:00:00 +0100 5513509 http://www.medworm.com/index.php?rid=5513508&cid=s_32073_162_f&fid=32073&url=http%3A%2F%2Fwww.jlr.org%2Fcgi%2Fcontent%2Fshort%2F53%2F1%2F28%3Frss%3D1 Lipid droplets are evolutionarily conserved organelles where cellular fat storage and mobilization are exquisitely regulated. Recent studies have defined lipid droplets in C. elegans and explored how they are regulated by genetic and dietary factors. C. elegans offers unique opportunities to visualize lipid droplets at single-cell resolution in live animals. The development of novel microscopy techniques and protein markers for lipid droplets will accelerate studies on how nutritional states and subcellular organization are linked in vivo. Together with powerful tools for genetic and biochemical analysis of metabolic pathways, alteration in lipid droplet abundance, size, and distribution in C. elegans can be readily connected to whole-animal energy homeostasis, behavior, and life span. The... The Journal of Lipid Research journals http://www.medworm.com/rss/comments.php?id=5513508 Thu, 15 Dec 2011 05:00:00 +0100 5513508 http://www.medworm.com/index.php?rid=5513507&cid=s_32073_162_f&fid=32073&url=http%3A%2F%2Fwww.jlr.org%2Fcgi%2Fcontent%2Fshort%2F53%2F1%2F4%3Frss%3D1 As the specific composition of lipids is essential for the maintenance of membrane integrity, enzyme function, ion channels, and membrane receptors, an alteration in lipid composition or metabolism may be one of the crucial changes occurring during skeletal and cardiac myopathies. Although the inheritance (autosomal dominant, autosomal recessive, and X-linked traits) and underlying/defining mutations causing these myopathies are known, the contribution of lipid homeostasis in the progression of these diseases needs to be established. The purpose of this review is to present the current knowledge relating to lipid changes in inherited skeletal muscle disorders, such as Duchenne/Becker muscular dystrophy, myotonic muscular dystrophy, limb-girdle myopathic dystrophies, desminopathies, rostroc... The Journal of Lipid Research journals http://www.medworm.com/rss/comments.php?id=5513507 Thu, 15 Dec 2011 05:00:00 +0100 5513507 http://www.medworm.com/index.php?rid=5513506&cid=s_32073_162_f&fid=32073&url=http%3A%2F%2Fwww.jlr.org%2Fcgi%2Fcontent%2Fshort%2F53%2F1%2F1%3Frss%3D1 (Source: The Journal of Lipid Research) The Journal of Lipid Research journals http://www.medworm.com/rss/comments.php?id=5513506 Thu, 15 Dec 2011 05:00:00 +0100 5513506 http://www.medworm.com/index.php?rid=5398185&cid=s_32073_162_f&fid=32073&url=http%3A%2F%2Fwww.jlr.org%2Fcgi%2Fcontent%2Fshort%2F52%2F12%2F2341%3Frss%3D1 Most current assays of HDL functional properties are cell-based. We have developed a fluorometric biochemical assay based on the oxidation of dihydrorhodamine 123 (DHR) by HDL. This cell-free assay assesses the intrinsic ability of HDL to be oxidized by measuring increasing fluorescence due to DHR oxidation over time. The assay distinguishes the oxidative potential of HDL taken from different persons, and the results are reproducible. Direct comparison of this measurement correlated well with results obtained using a validated cell-based assay (r2 = 0.62, P < 0.001). The assay can be scaled from a 96-well format to a 384-well format and, therefore, is suitable for high-throughput implementation. This new fluorometric method offers an inexpensive, accurate, and rapid means for determinin... The Journal of Lipid Research journals http://www.medworm.com/rss/comments.php?id=5398185 Fri, 11 Nov 2011 05:00:00 +0100 5398185 http://www.medworm.com/index.php?rid=5398184&cid=s_32073_162_f&fid=32073&url=http%3A%2F%2Fwww.jlr.org%2Fcgi%2Fcontent%2Fshort%2F52%2F12%2F2332%3Frss%3D1 Studies have shown a negative association between cellular cholesterol efflux and coronary artery disease (CAD). Standard protocol for quantitating cholesterol efflux involves labeling cells with [3H]cholesterol and measuring release of the labeled sterol. Using [3H]cholesterol is not ideal for the development of a high-throughput assay to screen large numbers of serum as would be required in studying the link between efflux and CAD. We compared efflux using a fluorescent sterol (boron dipyrromethene difluoride linked to sterol carbon-24, BODIPY-cholesterol) with that of [3H]cholesterol in J774 macrophages. Fractional efflux of BODIPY-cholesterol was significantly higher than that of [3H]cholesterol when apo A-I, HDL3, or 2% apoB-depleted human serum were used as acceptors. BODIPY-choleste... The Journal of Lipid Research journals http://www.medworm.com/rss/comments.php?id=5398184 Fri, 11 Nov 2011 05:00:00 +0100 5398184 http://www.medworm.com/index.php?rid=5398183&cid=s_32073_162_f&fid=32073&url=http%3A%2F%2Fwww.jlr.org%2Fcgi%2Fcontent%2Fshort%2F52%2F12%2F2323%3Frss%3D1 The composition of lipoproteins and the association of proteins with various particles are of much interest in the context of cardiovascular disease. Here, we describe a technique for the multidimensional analysis of lipoproteins and their associated apolipoproteins. Plasma is separated by size exclusion chromatography (SEC), and fractions are analyzed by reverse-phase arrays. SEC fractions are spotted on nitrocellulose slides and incubated with different antibodies against individual apolipoproteins or antibodies against various apolipoproteins. In this way, tens of analytes can be measured simultaneously in 100 μl of plasma from a single SEC separation. This methodology is particularly suited to simultaneous analysis of multiple proteins that may change their distribution to lipoprote... The Journal of Lipid Research journals http://www.medworm.com/rss/comments.php?id=5398183 Fri, 11 Nov 2011 05:00:00 +0100 5398183 http://www.medworm.com/index.php?rid=5398182&cid=s_32073_162_f&fid=32073&url=http%3A%2F%2Fwww.jlr.org%2Fcgi%2Fcontent%2Fshort%2F52%2F12%2F2314%3Frss%3D1 This work aims to combine chromatographic retention, high mass resolution and accuracy, MS/MS spectra, and a package for automated identification and quantitation of lipid species in one platform for lipidomic analysis. The instrumental setup elaborated comprises reversed-phase HPLC coupled to a Fourier transform ion cyclotron resonance mass spectrometer (LTQ-FT), and Lipid Data Analyzer (LDA) software. Data analysis for lipid species quantification in this platform is based on retention time, mass resolution of 200,000, and mass accuracy below 2 ppm. In addition, automatically generated MS/MS spectra provide structural information at molecular level. This LC/MS technology allows analyzing complex biological samples in a quantitative manner as shown here paradigmatically for murine lipid d... The Journal of Lipid Research journals http://www.medworm.com/rss/comments.php?id=5398182 Fri, 11 Nov 2011 05:00:00 +0100 5398182 http://www.medworm.com/index.php?rid=5398181&cid=s_32073_162_f&fid=32073&url=http%3A%2F%2Fwww.jlr.org%2Fcgi%2Fcontent%2Fshort%2F52%2F12%2F2304%3Frss%3D1 Subnormal HDL-cholesterol (HDL-C) and apolipoprotein (apo)AI levels are characteristic of familial hypercholesterolemia (FH), reflecting perturbed intravascular metabolism with compositional anomalies in HDL particles, including apoE enrichment. Does LDL-apheresis, which reduces HDL-cholesterol, apoAI, and apoE by adsorption, induce selective changes in HDL subpopulations, with relevance to atheroprotection? Five HDL subpopulations were fractionated from pre- and post-LDL-apheresis plasmas of normotriglyceridemic FH subjects (n = 11) on regular LDL-apheresis (>2 years). Apheresis lowered both plasma apoE (–62%) and apoAI (–16%) levels, with preferential, genotype-independent reduction in apoE. The mass ratio of HDL2:HDL3 was lowered from ~1:1 to 0.72:1 by apheresis, reflecti... The Journal of Lipid Research journals http://www.medworm.com/rss/comments.php?id=5398181 Fri, 11 Nov 2011 05:00:00 +0100 5398181 http://www.medworm.com/index.php?rid=5398180&cid=s_32073_162_f&fid=32073&url=http%3A%2F%2Fwww.jlr.org%2Fcgi%2Fcontent%2Fshort%2F52%2F12%2F2298%3Frss%3D1 The PPAR2 gene single nucleotide polymorphism (SNP) Pro12Ala has shown variable association with metabolic syndrome traits in healthy subjects. The RISCK Study investigated the effect of interaction between genotype and the ratio of polyunsaturated:saturated (P:S) fatty acid intake on plasma lipids in 367 white subjects (ages 30-70 years) at increased cardiometabolic risk. Interaction was determined after habitual diet at recruitment, at baseline after a 4-week high-SFA (HS) diet, and after a 24-week reference (HS), high-MUFA (HM), or low-fat (LF) diet. At recruitment, there were no significant associations between genotype and plasma lipids; however, P:S x genotype interaction influenced plasma total cholesterol (TC) (P = 0.02), LDL-cholesterol (LDL-C) (P = 0.002), and triglyceride (TG) (... The Journal of Lipid Research journals http://www.medworm.com/rss/comments.php?id=5398180 Fri, 11 Nov 2011 05:00:00 +0100 5398180 http://www.medworm.com/index.php?rid=5398179&cid=s_32073_162_f&fid=32073&url=http%3A%2F%2Fwww.jlr.org%2Fcgi%2Fcontent%2Fshort%2F52%2F12%2F2287%3Frss%3D1 Oxidative damage has been reported in Rett syndrome (RTT), a pervasive developmental disorder caused in up to 95% of cases by mutations in the X-linked methyl-CpG binding protein 2 gene. Herein, we have synthesized F2-dihomo-isoprostanes (F2-dihomo-IsoPs), peroxidation products from adrenic acid (22:4 n-6), a known component of myelin, and tested the potential value of F2-dihomo-IsoPs as a novel disease marker and its relationship with clinical presentation and disease progression. F2-dihomo-IsoPs were determined by gas chromatography/negative-ion chemical ionization tandem mass spectrometry. Newly synthesized F2-dihomo-IsoP isomers [ent-7(RS)-F2t-dihomo-IsoP and 17-F2t-dihomo-IsoP] were used as reference standards. The measured ions were the product ions at m/z 327 derived from the [M&nda... The Journal of Lipid Research journals http://www.medworm.com/rss/comments.php?id=5398179 Fri, 11 Nov 2011 05:00:00 +0100 5398179 http://www.medworm.com/index.php?rid=5398178&cid=s_32073_162_f&fid=32073&url=http%3A%2F%2Fwww.jlr.org%2Fcgi%2Fcontent%2Fshort%2F52%2F12%2F2279%3Frss%3D1 The 6 desaturase, encoded by FADS2, plays a crucial role in omega-3 and omega-6 fatty acid synthesis. These fatty acids are essential components of the central nervous system, and they act as precursors for eicosanoid signaling molecules and as direct modulators of gene expression. The polypyrimidine tract binding protein (PTB or hnRNP I) is a splicing factor that regulates alternative pre-mRNA splicing. Here, PTB is shown to bind an exonic splicing silencer element and repress alternative splicing of FADS2 into FADS2 AT1. PTB and FADS2AT1 were inversely correlated in neonatal baboon tissues, implicating PTB as a major regulator of tissue-specific FADS2 splicing. In HepG2 cells, PTB knockdown modulated alternative splicing of FADS2, as well as FADS3, a putative desaturase of unknown functi... The Journal of Lipid Research journals http://www.medworm.com/rss/comments.php?id=5398178 Fri, 11 Nov 2011 05:00:00 +0100 5398178 http://www.medworm.com/index.php?rid=5398177&cid=s_32073_162_f&fid=32073&url=http%3A%2F%2Fwww.jlr.org%2Fcgi%2Fcontent%2Fshort%2F52%2F12%2F2272%3Frss%3D1 In this study, using C323G mutant SR-BI, we showed that C323G mutant SR-BI lost its HDL binding and cholesteryl ester uptake activity, indicating that the highly conserved C323 is required for SR-BI-mediated HDL binding and cholesteryl ester uptake. Using a blocking antibody against C323 region, we demonstrated that C323 is directly involved in HDL binding and likely an HDL binding site. Using C323G mutant transgenic mouse model, we further demonstrated that C323 of SR-BI is required for regulating plasma cholesterol levels in vivo. Using redox reagents, we showed that physiological relevant levels of H2O2 upregulated the SR-BI-mediated cholesteryl ester uptake activity by 65%, whereas GSH or DTT significantly downregulated SR-BI-mediated cholesteryl ester uptake activity by 45%. C323 of S... The Journal of Lipid Research journals http://www.medworm.com/rss/comments.php?id=5398177 Fri, 11 Nov 2011 05:00:00 +0100 5398177 http://www.medworm.com/index.php?rid=5398176&cid=s_32073_162_f&fid=32073&url=http%3A%2F%2Fwww.jlr.org%2Fcgi%2Fcontent%2Fshort%2F52%2F12%2F2262%3Frss%3D1 Lipid transfer inhibitor protein (LTIP) exists in both active and inactive forms. Incubation (37°C) of plasma causes LTIP to transfer from a 470 kDa inactive complex to LDL where it is active. Here, we investigate the mechanisms underlying this movement. Inhibiting LCAT or cholesteryl ester transfer protein (CETP) reduced incubation-induced LTIP translocation by 40–50%. Blocking both LCAT and CETP completely prevented LTIP movement. Under appropriate conditions, either factor alone could drive maximum LTIP transfer to LDL. These data suggest that chemical modification of LDL, the 470 kDa complex, or both facilitate LTIP movement. To test this, LDL and the 470 kDa fraction were separately premodified by CETP and/or LCAT activity. Modification of the 470 kDa fraction had no effect ... The Journal of Lipid Research journals http://www.medworm.com/rss/comments.php?id=5398176 Fri, 11 Nov 2011 05:00:00 +0100 5398176 http://www.medworm.com/index.php?rid=5398175&cid=s_32073_162_f&fid=32073&url=http%3A%2F%2Fwww.jlr.org%2Fcgi%2Fcontent%2Fshort%2F52%2F12%2F2255%3Frss%3D1 In this study, we investigated whether serum amyloid A (SAA), an HDL apolipoprotein highly induced during inflammation, alters the ability of EL to metabolize HDL. We determined that EL hydrolyzes SAA-enriched HDL in vitro without liberating lipid-free apoA-I. Coexpression of SAA and EL in mice by adenoviral vector produced a significantly greater reduction in HDL-C and apoA-I than a corresponding level of expression of either SAA or EL alone. The loss of HDL occurred without any evidence of HDL remodeling to smaller particles that would be expected to have more rapid turnover. Studies with primary hepatocytes demonstrated that coexpression of SAA and EL markedly impeded ABCA1-mediated lipidation of apoA-I to form nascent HDL. Our findings suggest that a reduction in nascent HDL formation ... The Journal of Lipid Research journals http://www.medworm.com/rss/comments.php?id=5398175 Fri, 11 Nov 2011 05:00:00 +0100 5398175 http://www.medworm.com/index.php?rid=5398174&cid=s_32073_162_f&fid=32073&url=http%3A%2F%2Fwww.jlr.org%2Fcgi%2Fcontent%2Fshort%2F52%2F12%2F2245%3Frss%3D1 In animals, the product of cyclooxygenase reacting with arachidonic acid, prostaglandin(PG)H2, can undergo spontaneous rearrangement and nonenzymatic ring cleavage to form levuglandin(LG)E2 and LGD2. These LGs and their isomers are highly reactive -ketoaldehydes that form covalent adducts with proteins, DNA, and phosphatidylethanolamine in cells. Here, we isolated a novel oxidized LGD2 (ox-LGD2) from the red alga Gracilaria edulis and determined its planar structure. Additionally, ox-LGD2 was identified in some tissues of mice and in the lysate of phorbol-12-myristate-13-acetate (PMA)-treated THP-1 cells incubated with arachidonic acid using LC-MS/MS. These results suggest that ox-LGD2 is a common oxidized metabolite of LGD2. In the planar structure of ox-LGD2, H8 and H12 of LGD2 were dehy... The Journal of Lipid Research journals http://www.medworm.com/rss/comments.php?id=5398174 Fri, 11 Nov 2011 05:00:00 +0100 5398174 http://www.medworm.com/index.php?rid=5398173&cid=s_32073_162_f&fid=32073&url=http%3A%2F%2Fwww.jlr.org%2Fcgi%2Fcontent%2Fshort%2F52%2F12%2F2234%3Frss%3D1 Mixed background SHP–/– mice are resistant to diet-induced obesity due to increased energy expenditure caused by enhanced PGC-1α expression in brown adipocytes. However, congenic SHP–/– mice on the C57BL/6 background showed normal expression of PGC-1α and other genes involved in brown adipose tissue thermogenesis. Thus, we reinvestigated the impact of small heterodimer partner (SHP) deletion on diet-induced obesity and insulin resistance using congenic SHP–/– mice. Compared with their C57BL/6 wild-type counterparts, SHP–/– mice subjected to a 6 month challenge with a Western diet (WestD) were leaner but more glucose intolerant, showed hepatic insulin resistance despite decreased triglyceride accumulation and increased β-oxida... The Journal of Lipid Research journals http://www.medworm.com/rss/comments.php?id=5398173 Fri, 11 Nov 2011 05:00:00 +0100 5398173 http://www.medworm.com/index.php?rid=5398172&cid=s_32073_162_f&fid=32073&url=http%3A%2F%2Fwww.jlr.org%2Fcgi%2Fcontent%2Fshort%2F52%2F12%2F2226%3Frss%3D1 In conclusion, the similarly high turnover rates of both oleate and vaccenate readily suggest that remodeling is an important functional aspect of PL metabolism in CL. (Source: The Journal of Lipid Research) The Journal of Lipid Research journals http://www.medworm.com/rss/comments.php?id=5398172 Fri, 11 Nov 2011 05:00:00 +0100 5398172 http://www.medworm.com/index.php?rid=5398171&cid=s_32073_162_f&fid=32073&url=http%3A%2F%2Fwww.jlr.org%2Fcgi%2Fcontent%2Fshort%2F52%2F12%2F2209%3Frss%3D1 The generation of oxidized phospholipids in lipoproteins has been linked to vascular inflammation in atherosclerotic lesions. Products of phospholipid oxidation increase endothelial activation; however, their effects on macrophages are poorly understood, and it is unclear whether these effects are regulated by the biochemical pathways that metabolize oxidized phospholipids. We found that incubation of 1-palmitoyl-2-(5'-oxo-valeroyl)-sn-glycero-3-phosphocholine (POVPC) with THP-1-derived macrophages upregulated the expression of cytokine genes, including granulocyte/macrophage colony-stimulating factor (GM-CSF), tumor necrosis factor (TNF)-α, monocyte chemotactic protein 1 (MCP-1), interleukin (IL)-1β, IL-6, and IL-8. In these cells, reagent POVPC was either hydrolyzed to lyso-ph... The Journal of Lipid Research journals http://www.medworm.com/rss/comments.php?id=5398171 Fri, 11 Nov 2011 05:00:00 +0100 5398171 http://www.medworm.com/index.php?rid=5398170&cid=s_32073_162_f&fid=32073&url=http%3A%2F%2Fwww.jlr.org%2Fcgi%2Fcontent%2Fshort%2F52%2F12%2F2198%3Frss%3D1 Lipid droplets, also called lipid bodies (LB) in inflammatory cells, are important cytoplasmic organelles. However, little is known about the molecular characteristics and functions of LBs in human mast cells (MC). Here, we have analyzed the genesis and components of LBs during differentiation of human peripheral blood-derived CD34+ progenitors into connective tissue-type MCs. In our serum-free culture system, the maturing MCs, derived from 18 different donors, invariably developed triacylglycerol (TG)-rich LBs. Not known heretofore, the MCs transcribe the genes for perilipins (PLIN)1-4, but not PLIN5, and PLIN2 and PLIN3 display different degrees of LB association. Upon MC activation and ensuing degranulation, the LBs were not cosecreted with the cytoplasmic secretory granules. Exogenous ... The Journal of Lipid Research journals http://www.medworm.com/rss/comments.php?id=5398170 Fri, 11 Nov 2011 05:00:00 +0100 5398170 http://www.medworm.com/index.php?rid=5398169&cid=s_32073_162_f&fid=32073&url=http%3A%2F%2Fwww.jlr.org%2Fcgi%2Fcontent%2Fshort%2F52%2F12%2F2187%3Frss%3D1 Sulfogalactosylglycerolipid (SGG) is the major sulfoglycolipid of male germ cells. During spermatogenesis, apoptosis occurs in >50% of total germ cells. Sertoli cells phagocytose these apoptotic germ cells and degrade their components using lysosomal enzymes. Here we demonstrated that SGG was a physiological substrate of Sertoli lysosomal arylsulfatase A (ARSA). SGG accumulated in Sertoli cells of Arsa–/– mice, and at 8 months of age, this buildup led to lysosomal swelling and other cellular abnormalities typical of a lysosomal storage disorder. This disorder likely compromised Sertoli cell functions, manifesting as impaired spermatogenesis and production of sperm with near-zero fertilizing ability in vitro. Fecundity of Arsa–/– males was thus reduced when they w... The Journal of Lipid Research journals http://www.medworm.com/rss/comments.php?id=5398169 Fri, 11 Nov 2011 05:00:00 +0100 5398169 http://www.medworm.com/index.php?rid=5398168&cid=s_32073_162_f&fid=32073&url=http%3A%2F%2Fwww.jlr.org%2Fcgi%2Fcontent%2Fshort%2F52%2F12%2F2177%3Frss%3D1 The accumulation of lipids, including cholesterol, in the arterial wall plays a key role in the pathogenesis of atherosclerosis. Although several advances have been made in the detection and imaging of these lipid structures in plaque lesions, their morphology and composition have yet to be fully elucidated, particularly in different animal models of disease. To address this issue, we analyzed lipid morphology and composition in the atherosclerotic plaques of two animal models of disease, the low density lipoprotein receptor-deficient (LDLR–/–) mouse and the ApoE lipoprotein-deficient (ApoE–/–) mouse, utilizing hyperspectral coherent anti-Stokes Raman scattering (CARS) microscopy in combination with principal component analysis (PCA). Hyperspectral CARS imaging reve... The Journal of Lipid Research journals http://www.medworm.com/rss/comments.php?id=5398168 Fri, 11 Nov 2011 05:00:00 +0100 5398168 http://www.medworm.com/index.php?rid=5398167&cid=s_32073_162_f&fid=32073&url=http%3A%2F%2Fwww.jlr.org%2Fcgi%2Fcontent%2Fshort%2F52%2F12%2F2169%3Frss%3D1 In this study, we describe a novel benzazepine compound evacetrapib (LY2484595), which is a potent and selective inhibitor of CETP both in vitro and in vivo. Evacetrapib inhibited human recombinant CETP protein (5.5 nM IC50) and CETP activity in human plasma (36 nM IC50) in vitro. In double transgenic mice expressing human CETP and apoAI, evacetrapib exhibited an ex vivo CETP inhibition ED50 of less than 5 mg/kg at 8 h post oral dose and significantly elevated HDL cholesterol. Importantly, no blood pressure elevation was observed in rats dosed with evacetrapib at high exposure multiples compared with the positive control, torcetrapib. In addition, in a human adrenal cortical carcinoma cell line (H295R cells), evacetrapib did not induce aldosterone or cortisol biosynthesis whereas torcetrap... The Journal of Lipid Research journals http://www.medworm.com/rss/comments.php?id=5398167 Fri, 11 Nov 2011 05:00:00 +0100 5398167 http://www.medworm.com/index.php?rid=5398166&cid=s_32073_162_f&fid=32073&url=http%3A%2F%2Fwww.jlr.org%2Fcgi%2Fcontent%2Fshort%2F52%2F12%2F2159%3Frss%3D1 We examined the contribution of LD perilipin composition to the physical and metabolic interactions between LD and mitochondria using multiple techniques: confocal imaging, electron microscopy (EM), and lipid storage and utilization measurements. Using neonatal cardiomyocytes, reconstituted cell culture models, and rodent heart tissues, we found that perilipin 5 (Plin5) recruits mitochondria to the LD surface through a C-terminal region. Compared with control cells, Plin5-expressing cells show decreased LD hydrolysis, decreased palmitate β-oxidation, and increased palmitate incorporation into triglycerides in basal conditions, whereas in stimulated conditions, LD hydrolysis inhibition is lifted and FA released for β-oxidation. These results suggest that Plin5 regulates oxidative ... The Journal of Lipid Research journals http://www.medworm.com/rss/comments.php?id=5398166 Fri, 11 Nov 2011 05:00:00 +0100 5398166 http://www.medworm.com/index.php?rid=5398165&cid=s_32073_162_f&fid=32073&url=http%3A%2F%2Fwww.jlr.org%2Fcgi%2Fcontent%2Fshort%2F52%2F12%2F2148%3Frss%3D1 In this study, we investigated the membrane organization of CDP-diacylglycerol synthesis. Separation of mildly disrupted A431 cell membranes on sucrose density gradients revealed cofractionation of CDS and PI synthase activities with cholesterol-poor, endoplasmic reticulum (ER) membranes and partial overlap with plasma membrane caveolae. Cofractionation of CDS activity with caveolae was also observed when low-buoyant density caveolin-enriched membranes were prepared using a carbonate-based method. However, immunoisolation studies determined that CDS activity localized to ER membrane fragments containing calnexin and type III inositol (1,4,5)-trisphosphate receptors but not to caveolae. Membrane fragmentation in neutral pH buffer established that CDP-diacylglycerol and PI syntheses were res... The Journal of Lipid Research journals http://www.medworm.com/rss/comments.php?id=5398165 Fri, 11 Nov 2011 05:00:00 +0100 5398165 http://www.medworm.com/index.php?rid=5398164&cid=s_32073_162_f&fid=32073&url=http%3A%2F%2Fwww.jlr.org%2Fcgi%2Fcontent%2Fshort%2F52%2F12%2F2136%3Frss%3D1 The human lipodystrophy gene product Berardinelli-Seip congenital lipodystrophy 2/seipin has been implicated in adipocyte differentiation, lipid droplet (LD) formation, and motor neuron development. However, the molecular function of seipin and its disease-causing mutants remains to be elucidated. Here, we characterize seipin and its mis-sense mutants: N88S/S90L (both linked to motoneuron disorders) and A212P (linked to lipodystrophy) in cultured mammalian cells. Knocking down seipin significantly increases oleate incorporation into triacylglycerol (TAG) and the steady state level of TAG, and induces the proliferation and clustering of small LDs. By contrast, overexpression of seipin reduces TAG synthesis, leading to decreased formation of LDs. Expression of the A212P mutant, however, had ... The Journal of Lipid Research journals http://www.medworm.com/rss/comments.php?id=5398164 Fri, 11 Nov 2011 05:00:00 +0100 5398164 http://www.medworm.com/index.php?rid=5398163&cid=s_32073_162_f&fid=32073&url=http%3A%2F%2Fwww.jlr.org%2Fcgi%2Fcontent%2Fshort%2F52%2F12%2F2111%3Frss%3D1 Steroid hormones are made from cholesterol, primarily derived from lipoproteins that enter cells via receptor-mediated endocytosis. In endo-lysosomes, cholesterol is released from cholesterol esters by lysosomal acid lipase (LAL; disordered in Wolman disease) and exported via Niemann-Pick type C (NPC) proteins (disordered in NPC disease). These diseases are characterized by accumulated cholesterol and cholesterol esters in most cell types. Mechanisms for trans-cytoplasmic cholesterol transport, membrane insertion, and retrieval from membranes are less clear. Cholesterol esters and "free" cholesterol are enzymatically interconverted in lipid droplets. Cholesterol transport to the cholesterol-poor outer mitochondrial membrane (OMM) appears to involve cholesterol transport proteins. Cytochrom... The Journal of Lipid Research journals http://www.medworm.com/rss/comments.php?id=5398163 Fri, 11 Nov 2011 05:00:00 +0100 5398163 http://www.medworm.com/index.php?rid=5322274&cid=s_32073_162_f&fid=32073&url=http%3A%2F%2Fwww.jlr.org%2Fcgi%2Fcontent%2Fshort%2F52%2F11%2F2101%3Frss%3D1 We describe a technique to remove chlorophyll using quick, simple solid phase extraction (SPE) and directly compare the intact TAG composition of four microalgae species (Phaeodactylum tricornutum, Nannochloropsis salina, Nannochloropsis oculata, and Tetraselmis suecica) using MALDI time-of-flight (TOF) mass spectrometry (MS), ESI linear ion trap-orbitrap (LTQ Orbitrap) MS, and 1H NMR spectroscopy. Direct MS analysis is particularly effective to compare the polyunsaturated fatty acid (PUFA) composition for triacylglycerols because oxidation can often degrade samples upon derivatization. Using these methods, we observed that T. suecica contains significant PUFA levels with respect to other microalgae. This method is applicable for high-throughput MS screening of microalgae TAG profiles and ... The Journal of Lipid Research journals http://www.medworm.com/rss/comments.php?id=5322274 Fri, 14 Oct 2011 04:00:00 +0100 5322274 http://www.medworm.com/index.php?rid=5322273&cid=s_32073_162_f&fid=32073&url=http%3A%2F%2Fwww.jlr.org%2Fcgi%2Fcontent%2Fshort%2F52%2F11%2F2095%3Frss%3D1 The main causes of familial hypercholesterolemia (FH) are mutations in LDL receptor (LDLR) gene. Functional studies are necessary to demonstrate the LDLR function impairment caused by mutations and would be useful as a diagnostic tool if they allow discrimination between FH patients and controls. In order to identify the best method to detect LDLR activity, we compared continuous Epstein-Barr virus (EBV)-transformed B-lymphocytes and mitogen stimulated T-lymphocytes. In addition, we characterized both novel and known mutations in the LDLR gene. T-lymphocytes and EBV-transformed B-lymphocytes were obtained from peripheral blood of 24 FH patients and 24 control subjects. Functional assays were performed by incubation with fluorescent LDL followed by flow cytometry analysis. Residual LDLR act... The Journal of Lipid Research journals http://www.medworm.com/rss/comments.php?id=5322273 Fri, 14 Oct 2011 04:00:00 +0100 5322273 http://www.medworm.com/index.php?rid=5322272&cid=s_32073_162_f&fid=32073&url=http%3A%2F%2Fwww.jlr.org%2Fcgi%2Fcontent%2Fshort%2F52%2F11%2F2084%3Frss%3D1 An automated fluorescence microscopy assay using a nontoxic cholesterol binding protein, toxin domain 4, (D4), was developed in order to identify chemical compounds modifying intracellular cholesterol metabolism and distribution. Using this method, we screened a library of 1,056 compounds and identified 35 compounds that decreased D4 binding to the cell surface. Among them, 8 compounds were already reported to alter the biosynthesis or the intracellular distribution of cholesterol. The remaining 27 hit compounds were further analyzed biochemically and histochemically. Cell staining with another fluorescent cholesterol probe, filipin, revealed that 17 compounds accumulated cholesterol in the late endosomes. Five compounds decreased cholesterol biosynthesis, and two compounds inhibited the b... The Journal of Lipid Research journals http://www.medworm.com/rss/comments.php?id=5322272 Fri, 14 Oct 2011 04:00:00 +0100 5322272 http://www.medworm.com/index.php?rid=5322271&cid=s_32073_162_f&fid=32073&url=http%3A%2F%2Fwww.jlr.org%2Fcgi%2Fcontent%2Fshort%2F52%2F11%2F2070%3Frss%3D1 Although LDL is rendered proatherogenic by various experimental treatments (e.g., acetylation), the exact structural changes that drive LDL transformation in vivo remain enigmatic. Among the many hypothesized targets of oxidative modification are cholesterol esters (CE). This family of neutral lipids, which carries a highly unsaturated pool of fatty acyl groups, is the main component of both LDL particles and atherosclerotic plaques. Tandem mass spectrometry (MS/MS) was employed to reveal abundant and diverse oxidized CEs (oxCE), including novel oxidation products, within human peripheral vascular lesions. These oxCE species composed up to 40% of the total CE pool, with cholesteryl linoleate being oxidized to the greatest extent. Imaging mass spectrometry studies showed that oxCE was entir... The Journal of Lipid Research journals http://www.medworm.com/rss/comments.php?id=5322271 Fri, 14 Oct 2011 04:00:00 +0100 5322271 http://www.medworm.com/index.php?rid=5322270&cid=s_32073_162_f&fid=32073&url=http%3A%2F%2Fwww.jlr.org%2Fcgi%2Fcontent%2Fshort%2F52%2F11%2F2056%3Frss%3D1 X-adrenoleukodystrophy (X-ALD) is a peroxisomal metabolic disorder caused by mutations in the ABCD1 gene encoding the peroxisomal ABC transporter adrenoleukodystrophy protein (ALDP). The consistent metabolic abnormality in all forms of X-ALD is an inherited defect in the peroxisomal β-oxidation of very long chain FAs (VLCFAs >C22:0) and the resultant pathognomic accumulation of VLCFA. The accumulation of VLCFA leads to a neuroinflammatory disease process associated with demyelination of the cerebral white matter. The present study underlines the importance of a potent histone deacetylase (HDAC) inhibitor, suberoylanilide hydroxamic acid (SAHA) in inducing the expression of ABCD2 [adrenoleukodystrophy-related protein (ALDRP)], and normalizing the peroxisomal β-oxidation, as wel... The Journal of Lipid Research journals http://www.medworm.com/rss/comments.php?id=5322270 Fri, 14 Oct 2011 04:00:00 +0100 5322270 http://www.medworm.com/index.php?rid=5322269&cid=s_32073_162_f&fid=32073&url=http%3A%2F%2Fwww.jlr.org%2Fcgi%2Fcontent%2Fshort%2F52%2F11%2F2043%3Frss%3D1 Recent studies have identified an ABCA1-dependent, phosphatidylcholine-rich microdomain, called the "high-capacity binding site" (HCBS), that binds apoA-I and plays a pivotal role in apoA-I lipidation. Here, using sucrose gradient fractionation, we obtained evidence that both ABCA1 and [125I]apoA-I associated with the HCBS were found localized to nonraft microdomains. Interestingly, phosphatidylcholine (PtdCho) was selectively removed from nonraft domains by apoA-I, whereas sphingomyelin and cholesterol were desorbed from both detergent-resistant membranes and nonraft domains. The modulatory role of cholesterol on apoA-I binding to ABCA1/HCBS was also examined. Loading cells with cholesterol resulted in a drastic reduction in apoA-I binding. Conversely, depletion of membrane cholesterol by... The Journal of Lipid Research journals http://www.medworm.com/rss/comments.php?id=5322269 Fri, 14 Oct 2011 04:00:00 +0100 5322269 http://www.medworm.com/index.php?rid=5322268&cid=s_32073_162_f&fid=32073&url=http%3A%2F%2Fwww.jlr.org%2Fcgi%2Fcontent%2Fshort%2F52%2F11%2F2032%3Frss%3D1 Adipose triglyceride lipase (ATGL) catalyzes the first step of triacylglycerol hydrolysis in adipocytes. Abhydrolase domain 5 (ABHD5) increases ATGL activity by an unknown mechanism. Prior studies have suggested that the expression of ABHD5 is limiting for lipolysis in adipocytes, as addition of recombinant ABHD5 increases in vitro TAG hydrolase activity of adipocyte lysates. To test this hypothesis in vivo, we generated transgenic mice that express 6-fold higher ABHD5 in adipose tissue relative to wild-type (WT) mice. In vivo lipolysis increased to a similar extent in ABHD5 transgenic and WT mice following an overnight fast or injection of either a β-adrenergic receptor agonist or lipopolysaccharide. Similarly, basal and β-adrenergic-stimulated lipolysis was comparable in adipoc... The Journal of Lipid Research journals http://www.medworm.com/rss/comments.php?id=5322268 Fri, 14 Oct 2011 04:00:00 +0100 5322268 http://www.medworm.com/index.php?rid=5322267&cid=s_32073_162_f&fid=32073&url=http%3A%2F%2Fwww.jlr.org%2Fcgi%2Fcontent%2Fshort%2F52%2F11%2F2021%3Frss%3D1 Chronic alcohol consumption is associated with fatty liver disease in mammals. The object of this study was to gain an understanding of dysregulated lipid metabolism in alcohol-fed C57BL/6 mice using a targeted lipidomic approach. Liquid chromatography tandem mass spectrometry was used to analyze several lipid classes, including free fatty acids, fatty acyl-CoAs, fatty acid ethyl esters, sphingolipids, ceramides, and endocannabinoids, in plasma and liver samples from control and alcohol-fed mice. The interpretation of lipidomic data was augmented by gene expression analyses for important metabolic enzymes in the lipid pathways studied. Alcohol feeding was associated with i) increased hepatic free fatty acid levels and decreased fatty acyl-CoA levels associated with decreased mitochondrial ... The Journal of Lipid Research journals http://www.medworm.com/rss/comments.php?id=5322267 Fri, 14 Oct 2011 04:00:00 +0100 5322267 http://www.medworm.com/index.php?rid=5322266&cid=s_32073_162_f&fid=32073&url=http%3A%2F%2Fwww.jlr.org%2Fcgi%2Fcontent%2Fshort%2F52%2F11%2F2012%3Frss%3D1 The unicellular green alga Chlamydomonas has frequently been used as a eukaryotic model system to study intracellular phospholipid signaling pathways in response to environmental stresses. Earlier, we found that hypersalinity induced a rapid increase in the putative lipid second messenger, phosphatidic acid (PA), which was suggested to be generated via activation of a phospholipase D (PLD) pathway and the combined action of a phospholipase C/diacylglycerol kinase (PLC/DGK) pathway. Lysophosphatidic acid (LPA) was also increased and was suggested to reflect a phospholipase A2 (PLA2) activity based on pharmacological evidence. The question of PA's and LPA's origin is, however, more complicated, especially as both function as precursors in the biosynthesis of phospho- and galactolipids. To ad... The Journal of Lipid Research journals http://www.medworm.com/rss/comments.php?id=5322266 Fri, 14 Oct 2011 04:00:00 +0100 5322266 http://www.medworm.com/index.php?rid=5322265&cid=s_32073_162_f&fid=32073&url=http%3A%2F%2Fwww.jlr.org%2Fcgi%2Fcontent%2Fshort%2F52%2F11%2F2005%3Frss%3D1 This study tested the hypothesis that inhibition of Pla2g1b protects against diet-induced hyperlipidemia. Results showed that the Pla2g1b–/– mice had decreased plasma triglyceride and cholesterol levels compared with Pla2g1b+/+ mice subsequent to feeding a high-fat, high-carbohydrate (hypercaloric) diet. These differences were evident before differences in body weight gains were observed. Injection of Poloxamer 407 to inhibit lipolysis revealed decreased VLDL production in Pla2g1b–/– mice. Supplementation with lysophosphatidylcholine, the product of Pla2g1b hydrolysis, restored VLDL production rates in Pla2g1b–/– mice and further elevated VLDL production in Pla2g1b+/+ mice. The Pla2g1b–/– mice also displayed decreased postprandial lipidemia c... The Journal of Lipid Research journals http://www.medworm.com/rss/comments.php?id=5322265 Fri, 14 Oct 2011 04:00:00 +0100 5322265 http://www.medworm.com/index.php?rid=5322264&cid=s_32073_162_f&fid=32073&url=http%3A%2F%2Fwww.jlr.org%2Fcgi%2Fcontent%2Fshort%2F52%2F11%2F1995%3Frss%3D1 Seven Z-octadecenoic acids having the double bond located in positions 6Z to 13Z were photooxidized. The resulting hydroperoxy-E-octadecenoic acids [HpOME(E)] were resolved by chiral phase-HPLC-MS, and the absolute configurations of the enantiomers were determined by gas chromatographic analysis of diastereoisomeric derivatives. The MS/MS/MS spectra showed characteristic fragments, which were influenced by the distance between the hydroperoxide and carboxyl groups. These fatty acids were then investigated as substrates of cyclooxygenase-1 (COX-1), manganese lipoxygenase (MnLOX), and the (8R)-dioxygenase (8R-DOX) activities of two linoleate diol synthases (LDS) and 10R-DOX. COX-1 and MnLOX abstracted hydrogen at C-11 of (12Z)-18:1 and C-12 of (13Z)-18:1. (11Z)-18:1 was subject to hydrogen a... The Journal of Lipid Research journals http://www.medworm.com/rss/comments.php?id=5322264 Fri, 14 Oct 2011 04:00:00 +0100 5322264 http://www.medworm.com/index.php?rid=5322263&cid=s_32073_162_f&fid=32073&url=http%3A%2F%2Fwww.jlr.org%2Fcgi%2Fcontent%2Fshort%2F52%2F11%2F1984%3Frss%3D1 Apolipoprotein A-IV (apoA-IV) is synthesized by intestinal enterocytes during lipid absorption and secreted into lymph on the surface of nascent chylomicrons. A compelling body of evidence supports a central role of apoA-IV in facilitating intestinal lipid absorption and in regulating satiety, yet a longstanding conundrum is that no abnormalities in fat absorption, feeding behavior, or weight gain were observed in chow-fed apoA-IV knockout (A4KO) mice. Herein we reevaluated the impact of apoA-IV expression in C57BL6 and A4KO mice fed a high-fat diet. Fat balance and lymph cannulation studies found no effect of intestinal apoA-IV gene expression on the efficiency of fatty acid absorption, but gut sac transport studies revealed that apoA-IV differentially modulates lipid transport and the nu... The Journal of Lipid Research journals http://www.medworm.com/rss/comments.php?id=5322263 Fri, 14 Oct 2011 04:00:00 +0100 5322263 http://www.medworm.com/index.php?rid=5322262&cid=s_32073_162_f&fid=32073&url=http%3A%2F%2Fwww.jlr.org%2Fcgi%2Fcontent%2Fshort%2F52%2F11%2F1974%3Frss%3D1 Given the increased prevalence of cardiovascular disease in the world, the search for genetic variations that impact risk factors associated with the development of this disease continues. Multiple genetic association studies demonstrate that procollagen C-proteinase enhancer 2 (PCPE2) modulates HDL levels. Recent studies revealed an unexpected role for this protein in the proteolytic processing of pro-apolipoprotein (apo) A-I by enhancing the cleavage of the hexapeptide extension present at the N-terminus of apoA-I. To investigate the role of the PCPE2 protein in an in vivo model, PCPE2-deficient (PCPE2 KO) mice were examined, and a detailed characterization of plasma lipid profiles, apoA-I, HDL speciation, and function was done. Results of isoelectric focusing (IEF) electrophoresis toget... The Journal of Lipid Research journals http://www.medworm.com/rss/comments.php?id=5322262 Fri, 14 Oct 2011 04:00:00 +0100 5322262 http://www.medworm.com/index.php?rid=5322261&cid=s_32073_162_f&fid=32073&url=http%3A%2F%2Fwww.jlr.org%2Fcgi%2Fcontent%2Fshort%2F52%2F11%2F1965%3Frss%3D1 Cholesteryl ester transfer protein (CETP) transfers cholesteryl ester (CE) and triglyceride between HDL and apoB-containing lipoproteins. Anacetrapib (ANA), a reversible inhibitor of CETP, raises HDL cholesterol (HDL-C) and lowers LDL cholesterol in dyslipidemic patients; however, the effects of ANA on cholesterol/lipoprotein metabolism in a dyslipidemic hamster model have not been demonstrated. To test whether ANA (60mg/kg/day, 2 weeks) promoted reverse cholesterol transport (RCT), 3H-cholesterol-loaded macrophages were injected and 3H-tracer levels were measured in HDL, liver, and feces. Compared to controls, ANA inhibited CETP (94%) and increased HDL-C (47%). 3H-tracer in HDL increased by 69% in hamsters treated with ANA, suggesting increased cholesterol efflux from macrophages to HDL. ... The Journal of Lipid Research journals http://www.medworm.com/rss/comments.php?id=5322261 Fri, 14 Oct 2011 04:00:00 +0100 5322261 http://www.medworm.com/index.php?rid=5322260&cid=s_32073_162_f&fid=32073&url=http%3A%2F%2Fwww.jlr.org%2Fcgi%2Fcontent%2Fshort%2F52%2F11%2F1957%3Frss%3D1 Statins and nitrogenous bisphosphonates (NBP) inhibit 3-hydroxy-3-methylglutaryl-coenzyme-A reductase (HMGCR) and farnesyl diphosphate synthase (FDPS), respectively, leading to depletion of farnesyl diphosphate (FPP) and disruption of protein prenylation. Squalene synthase (SQS) utilizes FPP in the first committed step from the mevalonate pathway toward cholesterol biosynthesis. Herein, we have identified novel bisphosphonates as potent and specific inhibitors of SQS, including the tetrasodium salt of 9-biphenyl-4,8-dimethyl-nona-3,7-dienyl-1,1-bisphosphonic acid (compound 5). Compound 5 reduced cholesterol biosynthesis and lead to a substantial intracellular accumulation of FPP without reducing cell viability in HepG2 cells. At high concentrations, lovastatin and zoledronate impaired prot... The Journal of Lipid Research journals http://www.medworm.com/rss/comments.php?id=5322260 Fri, 14 Oct 2011 04:00:00 +0100 5322260 http://www.medworm.com/index.php?rid=5322259&cid=s_32073_162_f&fid=32073&url=http%3A%2F%2Fwww.jlr.org%2Fcgi%2Fcontent%2Fshort%2F52%2F11%2F1949%3Frss%3D1 In rodents, bile salt-stimulated lipase (BSSL) and pancreatic lipase-related protein 2 (PLRP2) are the dominant lipases expressed in the exocrine pancreas in early life when milk is the main food. The aim of the present study was to evaluate whether BSSL and PLRP2 are also key enzymes in neonatal intestinal fat digestion. Using Caco-2 cells as a model for the small intestinal epithelium, purified human enzymes were incubated in the apical compartment with substrates, bile salt composition and concentrations physiologic to newborn infants. Both BSSL and PLRP2 hydrolyzed triglycerides (TG) to free FA and glycerol. Released FA were absorbed by the cells and reesterfied to TG. Together, BSSL and PLRP2 had a synergistic effect, increasing cellular uptake and reesterification 4-fold compared wit... The Journal of Lipid Research journals http://www.medworm.com/rss/comments.php?id=5322259 Fri, 14 Oct 2011 04:00:00 +0100 5322259 http://www.medworm.com/index.php?rid=5322258&cid=s_32073_162_f&fid=32073&url=http%3A%2F%2Fwww.jlr.org%2Fcgi%2Fcontent%2Fshort%2F52%2F11%2F1936%3Frss%3D1 We describe for the first time the involvement of SHP2 activity in the regulation of the expression of the fatty acid-metabolizing enzyme ACSL4. (Source: The Journal of Lipid Research) The Journal of Lipid Research journals http://www.medworm.com/rss/comments.php?id=5322258 Fri, 14 Oct 2011 04:00:00 +0100 5322258 http://www.medworm.com/index.php?rid=5322257&cid=s_32073_162_f&fid=32073&url=http%3A%2F%2Fwww.jlr.org%2Fcgi%2Fcontent%2Fshort%2F52%2F11%2F1927%3Frss%3D1 A-C1 protein is the product of a tumor suppressor gene negatively regulating the oncogene Ras and belongs to the HRASLS (HRAS-like suppressor) subfamily. We recently found that four members of this subfamily expressed in human tissues function as phospholipid-metabolizing enzymes. Here we examined a possible enzyme activity of A-C1. The homogenates of COS-7 cells overexpressing recombinant A-C1s from human, mouse, and rat showed a phospholipase A1/2 (PLA1/2) activity toward phosphatidylcholine (PC). This finding was confirmed with the purified A-C1. The activity was Ca2+ independent, and dithiothreitol and Nonidet P-40 were indispensable for full activity. Phosphatidylethanolamine (PE) was also a substrate and the phospholipase A1 (PLA1) activity was dominant over the PLA2 activity. Furthe... The Journal of Lipid Research journals http://www.medworm.com/rss/comments.php?id=5322257 Fri, 14 Oct 2011 04:00:00 +0100 5322257 http://www.medworm.com/index.php?rid=5322256&cid=s_32073_162_f&fid=32073&url=http%3A%2F%2Fwww.jlr.org%2Fcgi%2Fcontent%2Fshort%2F52%2F11%2F1885%3Frss%3D1 This review integrates historical biochemical and modern genetic findings that underpin our understanding of the low-density lipoprotein (LDL) dyslipidemias that bear on human disease. These range from life-threatening conditions of infancy through severe coronary heart disease of young adulthood, to indolent disorders of middle- and old-age. We particularly focus on the biological aspects of those gene mutations and variants that impact on sterol absorption and hepatobiliary excretion via specific membrane transporter systems (NPC1L1, ABCG5/8); the incorporation of dietary sterols (MTP) and of de novo synthesized lipids (HMGCR, TRIB1) into apoB-containing lipoproteins (APOB) and their release into the circulation (ANGPTL3, SARA2, SORT1); and receptor-mediated uptake of LDL and of intestin... The Journal of Lipid Research journals http://www.medworm.com/rss/comments.php?id=5322256 Fri, 14 Oct 2011 04:00:00 +0100 5322256 http://www.medworm.com/index.php?rid=5322255&cid=s_32073_162_f&fid=32073&url=http%3A%2F%2Fwww.jlr.org%2Fcgi%2Fcontent%2Fshort%2F52%2F11%2F1869%3Frss%3D1 Interest in lipolysis and the metabolism of triglyceride-rich lipoproteins was recently reignited by the discovery of severe hypertriglyceridemia (chylomicronemia) in glycosylphosphatidylinositol-anchored high density lipoprotein–binding protein 1 (GPIHBP1)-deficient mice. GPIHBP1 is expressed exclusively in capillary endothelial cells and binds lipoprotein lipase (LPL) avidly. These findings prompted speculation that GPIHBP1 serves as a binding site for LPL in the capillary lumen, creating "a platform for lipolysis." More recent studies have identified a second and more intriguing role for GPIHBP1—picking up LPL in the subendothelial spaces and transporting it across endothelial cells to the capillary lumen. Here, we review the studies that revealed that GPIHBP1 is the LPL tra... The Journal of Lipid Research journals http://www.medworm.com/rss/comments.php?id=5322255 Fri, 14 Oct 2011 04:00:00 +0100 5322255 http://www.medworm.com/index.php?rid=5322254&cid=s_32073_162_f&fid=32073&url=http%3A%2F%2Fwww.jlr.org%2Fcgi%2Fcontent%2Fshort%2F52%2F11%2F1865%3Frss%3D1 (Source: The Journal of Lipid Research) The Journal of Lipid Research journals http://www.medworm.com/rss/comments.php?id=5322254 Fri, 14 Oct 2011 04:00:00 +0100 5322254 http://www.medworm.com/index.php?rid=5322253&cid=s_32073_162_f&fid=32073&url=http%3A%2F%2Fwww.jlr.org%2Fcgi%2Fcontent%2Fshort%2F52%2F11%2F1861%3Frss%3D1 (Source: The Journal of Lipid Research) The Journal of Lipid Research journals http://www.medworm.com/rss/comments.php?id=5322253 Fri, 14 Oct 2011 04:00:00 +0100 5322253 http://www.medworm.com/index.php?rid=5322252&cid=s_32073_162_f&fid=32073&url=http%3A%2F%2Fwww.jlr.org%2Fcgi%2Fcontent%2Fshort%2F52%2F11%2F1857%3Frss%3D1 (Source: The Journal of Lipid Research) The Journal of Lipid Research journals http://www.medworm.com/rss/comments.php?id=5322252 Fri, 14 Oct 2011 04:00:00 +0100 5322252 http://www.medworm.com/index.php?rid=5205403&cid=s_32073_162_f&fid=32073&url=http%3A%2F%2Fwww.jlr.org%2Fcgi%2Fcontent%2Fshort%2F52%2F10%2F1847%3Frss%3D1 We evaluated dual-echo Dixon in-phase and out-of-phase (IP-OP), chemical shift imaging (CSI), and 1H MRS (hydrogen MR spectroscopy) in estimating fat content (FC) in phantoms and in livers of mice. Phantoms were made according to the volume percentage of fat ranging from 0% to 100%. The three MR methods were performed to measure FC in phantoms and in livers of obese leptin-deficient (ob/ob), human BSCL2/seipin gene knockout (SKO), and wild-type (WT) mice. The results were compared with known FC in phantoms and to a reference standard from mice by histological semiautomatic vacuole segmentation (HIS-S) procedure and liver lipid (LL) chemical analysis. In phantoms, CSI underestimated FC from 50% to 100%, to a lesser extent than IP-OP. In vivo, liver FC in ob/ob and SKO mice measured by the t... The Journal of Lipid Research journals http://www.medworm.com/rss/comments.php?id=5205403 Fri, 09 Sep 2011 04:00:00 +0100 5205403 http://www.medworm.com/index.php?rid=5205402&cid=s_32073_162_f&fid=32073&url=http%3A%2F%2Fwww.jlr.org%2Fcgi%2Fcontent%2Fshort%2F52%2F10%2F1837%3Frss%3D1 Phospholipid transfer protein activity (PLTPa) is associated with insulin levels and has been implicated in atherosclerotic disease in both mice and humans. Variation at the PLTP structural locus on chromosome 20 explains some, but not all, heritable variation in PLTPa. In order to detect quantitative trait loci (QTLs) elsewhere in the genome that affect PLTPa, we performed both oligogenic and single QTL linkage analysis on four large families (n = 227 with phenotype, n = 330 with genotype, n = 462 total), ascertained for familial combined hyperlipidemia. We detected evidence of linkage between PLTPa and chromosome 19p (lod = 3.2) for a single family and chromosome 2q (lod = 2.8) for all families. Inclusion of additional marker and exome sequence data in the analysis refined the linkage si... The Journal of Lipid Research journals http://www.medworm.com/rss/comments.php?id=5205402 Fri, 09 Sep 2011 04:00:00 +0100 5205402 http://www.medworm.com/index.php?rid=5205401&cid=s_32073_162_f&fid=32073&url=http%3A%2F%2Fwww.jlr.org%2Fcgi%2Fcontent%2Fshort%2F52%2F10%2F1829%3Frss%3D1 Levels of IgG and IgM autoantibodies (AA) to malondialdehyde (MDA)-LDL and apoB-immune complexes (ICs) were measured in 748 cases and 1,723 controls in the EPIC-Norfolk cohort and their association to coronary artery disease (CAD) events determined. We evaluated whether AA and IC modify CAD risk associated with secretory phospholipase A2 (sPLA2) type IIA mass and activity, lipoprotein-associated PLA2 activity, lipoprotein (a) [Lp(a)], oxidized phospholipids on apoB-100 (OxPL/apoB), myeloperoxidase, and high sensitivity C-reactive protein. IgG ICs were higher in cases versus controls (P = 0.02). Elevated levels of IgM AA and IC were inversely associated with Framingham Risk Score and number of metabolic syndrome criteria (p range 0.02–0.001). In regression analyses adjusted for age, s... The Journal of Lipid Research journals http://www.medworm.com/rss/comments.php?id=5205401 Fri, 09 Sep 2011 04:00:00 +0100 5205401 http://www.medworm.com/index.php?rid=5205400&cid=s_32073_162_f&fid=32073&url=http%3A%2F%2Fwww.jlr.org%2Fcgi%2Fcontent%2Fshort%2F52%2F10%2F1821%3Frss%3D1 In conclusion, this dietary trial indicates that the mechanisms linking dietary IP-TFA to cardiovascular disease may involve activation of the TNFα system. (Source: The Journal of Lipid Research) The Journal of Lipid Research journals http://www.medworm.com/rss/comments.php?id=5205400 Fri, 09 Sep 2011 04:00:00 +0100 5205400 http://www.medworm.com/index.php?rid=5205399&cid=s_32073_162_f&fid=32073&url=http%3A%2F%2Fwww.jlr.org%2Fcgi%2Fcontent%2Fshort%2F52%2F10%2F1810%3Frss%3D1 We report here the isolation and characterization of three novel 7-DHC-derived oxysterols (4α- and 4β-hydroxy-7-DHC and 24-hydroxy-7-DHC) in addition to DHCEO and 7-ketocholesterol (7-kChol) from the brain tissues of AY9944-treated rats. The identities of these five oxysterols were elucidated by HPLC-ultraviolet (UV), HPLC-MS, and 1D- and 2D-NMR. Quantification of 4α- and 4β-hydroxy-7-DHC, DHCEO, and 7-kChol in rat brain, liver, and serum were carried out by HPLC-MS using d7-DHCEO as an internal standard. With the exception of 7-kChol, these oxysterols were present only in tissues of AY9944-treated, but not control rats, and 7-kChol levels were markedly (>10-fold) higher in treated versus control rats. These findings are discussed in the context of the potential in... The Journal of Lipid Research journals http://www.medworm.com/rss/comments.php?id=5205399 Fri, 09 Sep 2011 04:00:00 +0100 5205399 http://www.medworm.com/index.php?rid=5205398&cid=s_32073_162_f&fid=32073&url=http%3A%2F%2Fwww.jlr.org%2Fcgi%2Fcontent%2Fshort%2F52%2F10%2F1795%3Frss%3D1 The apoA-I mimetic peptide L-4F [(Ac-D-W-F-K-A-F-Y-D-K-V-A-E-K-F-K-E-A-F-NH2) synthesized from all L-amino acids] has shown potential for the treatment of a variety of diseases. Here, we demonstrate that LDL promotes association between L-4F and HDL. A 2- to 3-fold greater association of L-4F with human HDL was observed in the presence of human LDL as compared with HDL by itself. This association further increased when LDL was supplemented with the oxidized lipid 15S-hydroxy-5Z, 8Z, 11Z, 13E-eicosatetraenoic acid (15HETE). Additionally, L-4F significantly (P = 0.02) promoted the transfer of 15HETE from LDL to HDL. The transfer of L-4F from LDL to HDL was demonstrated both in vitro and in C57BL/6J mice. L-4F, injected into C57BL/6J mice, associated rapidly with HDL and was then cleared quic... The Journal of Lipid Research journals http://www.medworm.com/rss/comments.php?id=5205398 Fri, 09 Sep 2011 04:00:00 +0100 5205398 http://www.medworm.com/index.php?rid=5205397&cid=s_32073_162_f&fid=32073&url=http%3A%2F%2Fwww.jlr.org%2Fcgi%2Fcontent%2Fshort%2F52%2F10%2F1787%3Frss%3D1 In this study, we investigated the role of the C-terminal domain for the activity of PCSK9. Experiments in which conserved residues and histidines on the surface of the C-terminal domain were mutated indicated that no specific residues of the C-terminal domain, apart from those responsible for maintaining the overall structure, are required for the activity of PCSK9. Rather, the net charge of the C-terminal domain is important. The more positively charged the C-terminal domain, the higher the activity toward the LDLR. Moreover, replacement of the C-terminal domain with an unrelated protein of comparable size led to significant activity of the chimeric protein.We conclude that the role of the evolutionary, poorly conserved C-terminal domain for the activity of PCSK9 reflects its overall pos... The Journal of Lipid Research journals http://www.medworm.com/rss/comments.php?id=5205397 Fri, 09 Sep 2011 04:00:00 +0100 5205397 http://www.medworm.com/index.php?rid=5205396&cid=s_32073_162_f&fid=32073&url=http%3A%2F%2Fwww.jlr.org%2Fcgi%2Fcontent%2Fshort%2F52%2F10%2F1775%3Frss%3D1 Through forward genetic screening in the mouse, a recessive mutation (couch potato, cpto) has been discovered that dramatically reduces plasma cholesterol levels across all lipoprotein classes. The cpto mutation altered a highly conserved residue in the Src homology domain 3 (SH3) domain of the Mia2 protein. Full-length hepatic Mia2 structurally and functionally resembled the related Mia3 protein. Mia2 localized to endoplasmic reticulum (ER) exit sites, suggesting a role in guiding proteins from the ER to the Golgi. Similarly to the Mia3 protein, Mia2’s cytosolic C terminus interacted directly with COPII proteins Sec23 and Sec24, whereas its lumenal SH3 domain may facilitate interactions with secretory cargo. Fractionation of plasma revealed that Mia2cpto/cpto mice had lower circulat... The Journal of Lipid Research journals http://www.medworm.com/rss/comments.php?id=5205396 Fri, 09 Sep 2011 04:00:00 +0100 5205396 http://www.medworm.com/index.php?rid=5125546&cid=s_32073_162_f&fid=32073&url=http%3A%2F%2Fwww.jlr.org%2Fcgi%2Fcontent%2Fshort%2F52%2F9%2F1773%3Frss%3D1 (Source: The Journal of Lipid Research) The Journal of Lipid Research journals http://www.medworm.com/rss/comments.php?id=5125546 Thu, 11 Aug 2011 23:00:00 +0100 5125546 http://www.medworm.com/index.php?rid=5125545&cid=s_32073_162_f&fid=32073&url=http%3A%2F%2Fwww.jlr.org%2Fcgi%2Fcontent%2Fshort%2F52%2F9%2F1765%3Frss%3D1 We describe a short-term assay method, the zebrafish obesogenic (ZO) test, for examining the effects of diet, drugs, and environmental contaminants, singly or in combination, on white adipose tissue (WAT) dynamics in live larvae. The ZO test is an intermediate step in obesity research, between in vitro and rodent assays, and may be also used to study the effect of environmental toxicants on the adiposity of aquatic species. The procedure, using Nile Red (NR) fluorescent probe to reveal adipocyte lipid droplets, is suitable for pharmaceutical or toxicological screening. Larvae treated at an environmentally-relevant concentration of tributyltin chloride (TBT), an environmental obesogen, exhibited a remarkable increase in adiposity, irrespective of the lipid composition of the background diet... The Journal of Lipid Research journals http://www.medworm.com/rss/comments.php?id=5125545 Thu, 11 Aug 2011 23:00:00 +0100 5125545 http://www.medworm.com/index.php?rid=5125544&cid=s_32073_162_f&fid=32073&url=http%3A%2F%2Fwww.jlr.org%2Fcgi%2Fcontent%2Fshort%2F52%2F9%2F1760%3Frss%3D1 Triacylglycerols (TG) are the major storage form of energy in eukaryotic organisms and are synthesized primarily by acyl CoA:1,2-diacylglycerol acyltransferase (DGAT) enzymes. In vitro DGAT activity has previously been quantified by measuring the incorporation of either radiolabeled fatty acyl CoA or diacylglycerol (DG) into TG. We developed a modified acyltransferase assay using a fluorescent fatty acyl CoA substrate to accurately quantify in vitro DGAT activity. In the modified assay, radioactive fatty acyl CoA is replaced with fluorescent NBD-palmitoyl CoA, which is used as a substrate by DGAT with DG to produce NBD-TG. After extraction with organic solvents and separation by thin layer chromatography, NBD-TG formation can be detected and accurately quantified using a fluorescent imagin... The Journal of Lipid Research journals http://www.medworm.com/rss/comments.php?id=5125544 Thu, 11 Aug 2011 23:00:00 +0100 5125544 http://www.medworm.com/index.php?rid=5125543&cid=s_32073_162_f&fid=32073&url=http%3A%2F%2Fwww.jlr.org%2Fcgi%2Fcontent%2Fshort%2F52%2F9%2F1755%3Frss%3D1 Low concentrations of bilirubin are associated with an increased risk for cardiovascular disease (CVD). Possibly, bilirubin exerts its effect through the protection of LDL from oxidation. Therefore, we examined whether low bilirubin might also be a risk marker for CVD in patients with familial hypercholesterolemia (FH) and whether statins influence serum bilirubin levels. Patients with FH were recruited from 37 lipid clinics. After a washout period of 6 weeks, all patients were started on monotherapy with simvastatin 80 mg for a period of two years. A total of 514 patients were enrolled. Bilirubin at baseline was inversely associated with the presence of CVD, also after adjustment for age, gender, presence of hypertension, and HDL cholesterol levels. Moreover, bilirubin levels were signifi... The Journal of Lipid Research journals http://www.medworm.com/rss/comments.php?id=5125543 Thu, 11 Aug 2011 23:00:00 +0100 5125543 http://www.medworm.com/index.php?rid=5125542&cid=s_32073_162_f&fid=32073&url=http%3A%2F%2Fwww.jlr.org%2Fcgi%2Fcontent%2Fshort%2F52%2F9%2F1747%3Frss%3D1 This study aimed to investigate whether plasma levels of HDL cholesterol (HDL-C) were associated with the risk of intracerebral hemorrhage (ICH). Plasma HDL-C was determined via enzymatic methods, and ICH was ascertained via medical history, physical examination, and brain imaging (computed tomography or magnetic resonance imaging). The multivariable logistic regression model was used to calculate the odds ratios (OR) and 95% confidence intervals (CI) of ICH according to levels of plasma cholesterol. A total of 170 patients with ICH were identified from 6,046 participants. After adjustment for conventional cardiovascular risk factors, the OR was 2.06 (95% CI, 1.25-3.12; P < 0.01) for participants in the first tertile of HDL-C levels (<1.38 mmol/l) and 1.13 (95% CI, 0.72-1.78; P = 0.5... The Journal of Lipid Research journals http://www.medworm.com/rss/comments.php?id=5125542 Thu, 11 Aug 2011 23:00:00 +0100 5125542 http://www.medworm.com/index.php?rid=5125541&cid=s_32073_162_f&fid=32073&url=http%3A%2F%2Fwww.jlr.org%2Fcgi%2Fcontent%2Fshort%2F52%2F9%2F1742%3Frss%3D1 This study shows the sex differences in kidney and urine Gb3 and kidney lyso-Gb3 levels in both wild-type and Fabry mice, and it suggests that these male-female differences should be taken into consideration when using murine models for Fabry disease. (Source: The Journal of Lipid Research) The Journal of Lipid Research journals http://www.medworm.com/rss/comments.php?id=5125541 Thu, 11 Aug 2011 23:00:00 +0100 5125541 http://www.medworm.com/index.php?rid=5125540&cid=s_32073_162_f&fid=32073&url=http%3A%2F%2Fwww.jlr.org%2Fcgi%2Fcontent%2Fshort%2F52%2F9%2F1733%3Frss%3D1 Expression of apoE in adipocytes has been shown to have an important role in modulating adipocyte triglyceride (TG) metabolism and gene expression that is independent of circulating and extracellular apoE. The impact of adipocyte expression of common human apoE isoforms was evaluated using adipocytes harvested from human apoE2, -3, and -4 knock-in mice. Expression of the apoE2 isoform was associated with an increase in adipocyte apoE gene expression and apoE synthesis. Newly synthesized apoE2 was unstable in adipocytes and demonstrated increased degradation and decreased secretion. ApoE2-expressing mice were hyperlipidemic, and had increased size of gonadal fat pads and of adipocytes, compared with apoE3 mice. In isolated cells, however, expression of the apoE2 isoform produced defective l... The Journal of Lipid Research journals http://www.medworm.com/rss/comments.php?id=5125540 Thu, 11 Aug 2011 23:00:00 +0100 5125540 http://www.medworm.com/index.php?rid=5125539&cid=s_32073_162_f&fid=32073&url=http%3A%2F%2Fwww.jlr.org%2Fcgi%2Fcontent%2Fshort%2F52%2F9%2F1723%3Frss%3D1 Acyl CoA:monoacylglycerol acyltransferase 2 (MGAT2) is thought to be crucial for dietary fat absorption. Indeed, mice lacking the enzyme (Mogat2–/–) are resistant to obesity and other metabolic disorders induced by high-fat feeding. However, these mice absorb normal quantities of fat. To explore whether a high level of dietary fat is an essential part of the underlying mechanism(s), we examined metabolic responses of Mogat2–/– mice to diets containing varying levels of fat. Mogat2–/– mice exhibited 10–15% increases in energy expenditure compared with wild-type littermates; although high levels of dietary fat exacerbated the effect, this phenotype was expressed even on a fat-free diet. When deprived of food, Mogat2–/– mice expended energ... The Journal of Lipid Research journals http://www.medworm.com/rss/comments.php?id=5125539 Thu, 11 Aug 2011 23:00:00 +0100 5125539 http://www.medworm.com/index.php?rid=5125538&cid=s_32073_162_f&fid=32073&url=http%3A%2F%2Fwww.jlr.org%2Fcgi%2Fcontent%2Fshort%2F52%2F9%2F1712%3Frss%3D1 In conclusion, in insulin-sensitive mice, circulating insulin stimulates tissue-specific partitioning of plasma-derived FA in WAT in part through activation of KATP channels in the CNS. Apparently, circulating insulin stimulates fatty acid uptake in WAT but not in BAT, directly and indirectly through the CNS. (Source: The Journal of Lipid Research) The Journal of Lipid Research journals http://www.medworm.com/rss/comments.php?id=5125538 Thu, 11 Aug 2011 23:00:00 +0100 5125538 http://www.medworm.com/index.php?rid=5125537&cid=s_32073_162_f&fid=32073&url=http%3A%2F%2Fwww.jlr.org%2Fcgi%2Fcontent%2Fshort%2F52%2F9%2F1702%3Frss%3D1 This study investigated the effect of chronic AMP-kinase (AMPK) activation with 5-aminoimidazole-4-carboxamide-1-β-D-ribofuranoside (AICAR) on white adipose tissue (WAT) metabolism and the implications for visceral (VC) and subcutaneous (SC) adiposity, whole body-energy homeostasis, and hypothalamic leptin sensitivity. Male Wistar rats received daily single intraperitoneal injections of either saline or AICAR (0.7g/kg body weight) for 4 and 8 weeks and were pair-fed throughout the study. AICAR-treated rats had reduced adiposity with increased mitochondrial density in VC and SC fat pads, which was accompanied by reduced circulating leptin and time-dependent and depot-specific regulation of AMPK phosphorylation and FA oxidation. Interestingly, the anorectic effect to exogenous leptin wa... The Journal of Lipid Research journals http://www.medworm.com/rss/comments.php?id=5125537 Thu, 11 Aug 2011 23:00:00 +0100 5125537 http://www.medworm.com/index.php?rid=5125536&cid=s_32073_162_f&fid=32073&url=http%3A%2F%2Fwww.jlr.org%2Fcgi%2Fcontent%2Fshort%2F52%2F9%2F1693%3Frss%3D1 Recent studies have established SIRT1 as an important regulator of lipid metabolism, although the mechanism of its action at the molecular level has not been revealed. Here, we show that knockdown of SIRT1 with the help of small hairpin RNA decreases basal and isoproterenol-stimulated lipolysis in cultured adipocytes. This effect is attributed, at least in part, to the suppression of the rate-limiting lipolytic enzyme, adipose triglyceride lipase (ATGL), at the level of transcription. Mechanistically, SIRT1 controls acetylation status and functional activity of FoxO1 that directly binds to the ATGL promoter and regulates ATGL gene transcription. We have also found that depletion of SIRT1 decreases AMP-dependent protein kinase (AMPK) activity in adipocytes. To determine the input of AMPK in... The Journal of Lipid Research journals http://www.medworm.com/rss/comments.php?id=5125536 Thu, 11 Aug 2011 23:00:00 +0100 5125536 http://www.medworm.com/index.php?rid=5125535&cid=s_32073_162_f&fid=32073&url=http%3A%2F%2Fwww.jlr.org%2Fcgi%2Fcontent%2Fshort%2F52%2F9%2F1683%3Frss%3D1 The primary products of de novo lipogenesis (DNL) are saturated fatty acids, which confer adverse cellular effects. Human adipocytes differentiated with no exogenous fat accumulated triacylglycerol (TG) in lipid droplets and differentiated normally. TG composition showed the products of DNL (saturated fatty acids from 12:0 to 18:0) together with unsaturated fatty acids (particularly 16:1n-7 and 18:1n-9) produced by elongation/desaturation. There was parallel upregulation of expression of genes involved in DNL and in fatty acid elongation and desaturation, suggesting coordinated control of expression. Enzyme products (desaturation ratios, elongation ratios, and total pathway flux) were also correlated with mRNA levels. We used 13C-labeled substrates to study the pathway of DNL. Glucose (5 m... The Journal of Lipid Research journals http://www.medworm.com/rss/comments.php?id=5125535 Thu, 11 Aug 2011 23:00:00 +0100 5125535 http://www.medworm.com/index.php?rid=5125534&cid=s_32073_162_f&fid=32073&url=http%3A%2F%2Fwww.jlr.org%2Fcgi%2Fcontent%2Fshort%2F52%2F9%2F1672%3Frss%3D1 This study shows how bioinformatics can be used effectively to reduce candidate gene lists for QTL related to complex traits. (Source: The Journal of Lipid Research) The Journal of Lipid Research journals http://www.medworm.com/rss/comments.php?id=5125534 Thu, 11 Aug 2011 23:00:00 +0100 5125534 http://www.medworm.com/index.php?rid=5125533&cid=s_32073_162_f&fid=32073&url=http%3A%2F%2Fwww.jlr.org%2Fcgi%2Fcontent%2Fshort%2F52%2F9%2F1660%3Frss%3D1 To devise successful imaging and therapeutic strategies, the identification of β-cell surface markers is one of the challenges in diabetes research that has to be resolved. We previously showed that IC2, a rat monoclonal IgM antibody, can be used for ex vivo determination of β-cell mass by imaging. Further progress toward the development of an antibody-based imaging agent was hampered by the lack of knowledge regarding the nature and composition of the IC2 antigen. Here, we show a series of systematic experiments involving classical lipid extraction and chromatography techniques combined with immunochemistry, which led to the identification of sphingomyelin as the target antigen assembled in the form of patches on the β-cell surface. Our findings were verified by modulating ... The Journal of Lipid Research journals http://www.medworm.com/rss/comments.php?id=5125533 Thu, 11 Aug 2011 23:00:00 +0100 5125533 http://www.medworm.com/index.php?rid=5125532&cid=s_32073_162_f&fid=32073&url=http%3A%2F%2Fwww.jlr.org%2Fcgi%2Fcontent%2Fshort%2F52%2F9%2F1652%3Frss%3D1 The pregnane X receptor (PXR, also known as SXR) is a nuclear hormone receptor activated by xenobiotics as well as diverse sterols and their metabolites. PXR functions as a xenobiotic sensor to coordinately regulate xenobiotic metabolism via transcriptional regulation of xenobiotic-detoxifying enzymes and transporters. Recent evidence indicates that PXR may also play an important role in lipid homeostasis and atherosclerosis. To define the role of PXR in atherosclerosis, we generated PXR and apoE double knockout (PXR–/–apoE–/–) mice. Here we show that deficiency of PXR did not alter plasma triglyceride and cholesterol levels in apoE–/– mice. However, PXR–/–apoE–/– mice had significantly decreased atherosclerotic cross-sectional le... The Journal of Lipid Research journals http://www.medworm.com/rss/comments.php?id=5125532 Thu, 11 Aug 2011 23:00:00 +0100 5125532 http://www.medworm.com/index.php?rid=5125531&cid=s_32073_162_f&fid=32073&url=http%3A%2F%2Fwww.jlr.org%2Fcgi%2Fcontent%2Fshort%2F52%2F9%2F1636%3Frss%3D1 Although short-term incubation of hepatocytes with oleic acid (OA) stimulates secretion of apolipoprotein B100 (apoB100), exposure to higher doses of OA for longer periods inhibits secretion in association with induction of endoplasmic reticulum (ER) stress. Palmitic acid (PA) induces ER stress, but its effects on apoB100 secretion are unclear. Docosahexaenoic acid (DHA) inhibits apoB100 secretion, but its effects on ER stress have not been studied. We compared the effects of each of these fatty acids on ER stress and apoB100 secretion in McArdle RH7777 (McA) cells: OA and PA induced ER stress and inhibited apoB100 secretion at higher doses; PA was more potent because it also increased the synthesis of ceramide. DHA did not induce ER stress but was the most potent inhibitor of apoB100 secr... The Journal of Lipid Research journals http://www.medworm.com/rss/comments.php?id=5125531 Thu, 11 Aug 2011 23:00:00 +0100 5125531 http://www.medworm.com/index.php?rid=5125530&cid=s_32073_162_f&fid=32073&url=http%3A%2F%2Fwww.jlr.org%2Fcgi%2Fcontent%2Fshort%2F52%2F9%2F1626%3Frss%3D1 Non-alcoholic fatty liver disease (NAFLD), the hepatic manifestation of the metabolic syndrome, can progress to steatohepatitis (NASH) and advanced liver disease. Mechanisms that underlie this progression remain poorly understood, partly due to lack of good animal models that resemble human NASH. We previously showed that several metabolic syndrome features that develop in LDL receptor-deficient (LDLR–/–) mice fed a diabetogenic diet are worsened by dietary cholesterol. To test whether dietary cholesterol can alter the hepatic phenotype in the metabolic syndrome, we fed LDLR–/– mice a high-fat, high-carbohydrate diabetogenic diet (DD) without or with added cholesterol (DDC). Both groups of mice developed obesity and insulin resistance. Hyperinsulinemia, dyslipidemia... The Journal of Lipid Research journals http://www.medworm.com/rss/comments.php?id=5125530 Thu, 11 Aug 2011 23:00:00 +0100 5125530 http://www.medworm.com/index.php?rid=5125529&cid=s_32073_162_f&fid=32073&url=http%3A%2F%2Fwww.jlr.org%2Fcgi%2Fcontent%2Fshort%2F52%2F9%2F1617%3Frss%3D1 In conclusion, OA induces hepatic lipogenesis, mediated predominantly by the AMPK/SREBP-1 pathway in rat hepatocytes and human hepatoma cell lines. (Source: The Journal of Lipid Research) The Journal of Lipid Research journals http://www.medworm.com/rss/comments.php?id=5125529 Thu, 11 Aug 2011 23:00:00 +0100 5125529 http://www.medworm.com/index.php?rid=5125528&cid=s_32073_162_f&fid=32073&url=http%3A%2F%2Fwww.jlr.org%2Fcgi%2Fcontent%2Fshort%2F52%2F9%2F1605%3Frss%3D1 Lipid transport in the brain is coordinated by glial-derived lipoproteins that contain apolipoprotein E (apoE) as their primary protein. Here we show that apoE is secreted from wild-type (WT) primary murine mixed glia as nascent lipoprotein subspecies ranging from 7.5 to 17 nm in diameter. Negative-staining electron microscropy (EM) revealed rouleaux, suggesting a discoidal structure. Potassium bromide (KBr) density gradient ultracentrifugation showed that all subspecies, except an 8.1 nm particle, were lipidated. Glia lacking the cholesterol transporter ABCA1 secreted only 8.1 nm particles, which were poorly lipidated and nondiscoidal but could accept lipids to form the full repertoire of WT apoE particles. Receptor-associated-protein (RAP)-mediated inhibition of apoE receptor function bl... The Journal of Lipid Research journals http://www.medworm.com/rss/comments.php?id=5125528 Thu, 11 Aug 2011 23:00:00 +0100 5125528 http://www.medworm.com/index.php?rid=5035952&cid=s_32073_162_f&fid=32073&url=http%3A%2F%2Fwww.jlr.org%2Fcgi%2Fcontent%2Fshort%2F52%2F8%2F1595%3Frss%3D1 Estrogen metabolites play important roles in the development of female-related disorders and homeostasis of the bone. To improve detectability, a validated gas chromatography-mass spectrometry (GC-MS) method was conducted with two-phase extractive ethoxycarbonlyation (EOC) and subsequent pentafluoropropionyl (PFP) derivatization was introduced. The resulting samples were separated through a high-temperature MXT-1 column within an 8 min run and were detected in the selected ion monitoring (SIM) mode. The optimized analytical conditions led to good separation with a symmetric peak shape for 19 estrogens as their EOC-PFP derivatives. The limit of quantification (LOQ) was from 0.02 to ~0.1 ng/ml for most estrogens analyzed, except for 2-hydroxyestriol (0.5 ng/ml). The devised method was found ... The Journal of Lipid Research journals http://www.medworm.com/rss/comments.php?id=5035952 Thu, 14 Jul 2011 23:00:00 +0100 5035952 http://www.medworm.com/index.php?rid=5035951&cid=s_32073_162_f&fid=32073&url=http%3A%2F%2Fwww.jlr.org%2Fcgi%2Fcontent%2Fshort%2F52%2F8%2F1583%3Frss%3D1 This study describes the use of a stable-isotope labeled precursor ([U-13C]palmitate) to analyze de novo sphingolipid biosynthesis by tandem mass spectrometry. It also describes factors to consider in interpreting the data, including the isotope's location (13C appears in three isotopomers and isotopologues: [M + 16] for the sphingoid base or N-acyl fatty acid, and [M + 32] for both); the isotopic enrichment of palmitoyl-CoA; and its elongation, desaturation, and incorporation into N-acyl-sphingolipids. For HEK293 cells incubated with 0.1 mM [U-13C]palmitic acid, ~60% of the total palmitoyl-CoA was 13C-labeled by 3 h (which was near isotopic equilibrium); with this correction, the rates of de novo biosynthesis of C16:0-ceramide, C16:0-monohexosylceramide, and C16:0-sphingomyelins were 62 &... The Journal of Lipid Research journals http://www.medworm.com/rss/comments.php?id=5035951 Thu, 14 Jul 2011 23:00:00 +0100 5035951 http://www.medworm.com/index.php?rid=5035950&cid=s_32073_162_f&fid=32073&url=http%3A%2F%2Fwww.jlr.org%2Fcgi%2Fcontent%2Fshort%2F52%2F8%2F1575%3Frss%3D1 Animal studies have suggested that angiopoietin-like 4 (Angptl4) regulates adiposity through central and peripheral mechanisms. The aim of this study was to investigate whether serum concentration and adipose tissue expression of Angptl4 are associated with obesity-related parameters in humans. Altogether, 75 dizygotic (DZ) and 46 monozygotic (MZ) twin pairs were studied, from the FinnTwin12 and FinnTwin16 cohorts. Among the MZ pairs, 21 were discordant for body mass index (BMI) (intra-pair BMI-difference >2.5 kg/m2, age 23–33 years). Serum Angptl4 (s-Angptl4) levels were measured by ELISA, and adipose tissue gene expression was analyzed by genome-wide transcript profiling. In MZ twin pairs discordant for BMI, s-Angptl4 and adipose tissue ANGPTL4 mRNA (at-ANGPTL4) levels were sign... The Journal of Lipid Research journals http://www.medworm.com/rss/comments.php?id=5035950 Thu, 14 Jul 2011 23:00:00 +0100 5035950 http://www.medworm.com/index.php?rid=5035949&cid=s_32073_162_f&fid=32073&url=http%3A%2F%2Fwww.jlr.org%2Fcgi%2Fcontent%2Fshort%2F52%2F8%2F1569%3Frss%3D1 Lecithin:cholesterol acyltransferase (LCAT) is the enzyme responsible for cholesterol esterification in plasma. LCAT is a major factor in HDL remodeling and metabolism, and it has long been believed to play a critical role in macrophage reverse cholesterol transport (RCT). The effect of LCAT on human atherogenesis is still controversial. In the present study, the plasma LCAT concentration was measured in all subjects (n = 540) not on drug treatment at the time of enrollment in the multicenter, longitudinal, observational IMPROVE study. Mean and maximum intima-media thickness (IMT) of the whole carotid tree was measured by B-mode ultrasonography in all subjects. In the entire cohort, LCAT quartiles were not associated with carotid mean and maximum IMT (P for trend 0.95 and 0.18, respectivel... The Journal of Lipid Research journals http://www.medworm.com/rss/comments.php?id=5035949 Thu, 14 Jul 2011 23:00:00 +0100 5035949 http://www.medworm.com/index.php?rid=5035948&cid=s_32073_162_f&fid=32073&url=http%3A%2F%2Fwww.jlr.org%2Fcgi%2Fcontent%2Fshort%2F52%2F8%2F1561%3Frss%3D1 Aldo-keto reductase 1B7 (AKR1B7) is proposed to play a role in detoxification of by-products of lipid peroxidation. In this article, we show that activation of the nuclear receptor farnesoid X receptor (FXR) induces AKR1B7 expression in the liver and intestine, and reduces the levels of malondialdehyde (MDA), the end product of lipid peroxidation, in the intestine but not in the liver. To determine whether AKR1B7 regulates MDA levels in vivo, we overexpressed AKR1B7 in the liver. Overexpression of AKR1B7 in the liver had no effect on hepatic or plasma MDA levels. Interestingly, hepatic expression of AKR1B7 significantly lowered plasma glucose levels in both wild-type and diabetic db/db mice, which was associated with reduced hepatic gluconeogenesis. Hepatic expression of AKR1B7 also signif... The Journal of Lipid Research journals http://www.medworm.com/rss/comments.php?id=5035948 Thu, 14 Jul 2011 23:00:00 +0100 5035948 http://www.medworm.com/index.php?rid=5035947&cid=s_32073_162_f&fid=32073&url=http%3A%2F%2Fwww.jlr.org%2Fcgi%2Fcontent%2Fshort%2F52%2F8%2F1551%3Frss%3D1 In this study, MALDI imaging MS was used to determine the localization of arachidonate- and docosahexaenoate-containing phospholipids in mouse lung. These PUFA-containing phospholipids were determined to be uniquely abundant at the lining of small and large airways, which were unequivocally identified by immunohistochemistry. In addition, it was found that the blood vessels present in the lung were characterized by sphingomyelin molecular species, and lung surfactant phospholipids appeared evenly distributed throughout the lung parenchyma, indicating alveolar localization. This technique revealed unexpected high concentrations of arachidonate- and docosahexaenoate-containing phospholipids lining the airways in pulmonary tissue, which could serve as precursors of lipid mediators affecting a... The Journal of Lipid Research journals http://www.medworm.com/rss/comments.php?id=5035947 Thu, 14 Jul 2011 23:00:00 +0100 5035947 http://www.medworm.com/index.php?rid=5035946&cid=s_32073_162_f&fid=32073&url=http%3A%2F%2Fwww.jlr.org%2Fcgi%2Fcontent%2Fshort%2F52%2F8%2F1542%3Frss%3D1 Scavenger receptors (ScRs) are a structurally unrelated family of receptors with the ability to bind modified low density lipoprotein (LDL) as well as a broad range of polyanionic ligands. CD68, whose expression is restricted to mononuclear phagocytes, is a unique ScR family member, owing to its lysosome associated membrane protein (LAMP)-like domain and predominant endosomal distribution. Knockout (ko) mice were generated to directly evaluate the role murine CD68 may play in oxidized LDL (Ox-LDL) uptake. However, CD68–/– macrophages took up Ox-LDL robustly. Likewise, no defects were observed in the ability of CD68–/– mononuclear phagocytes to take up or mount an effective innate response against a number of microbes. Curiously, CD68–/– mononuclear phago... The Journal of Lipid Research journals http://www.medworm.com/rss/comments.php?id=5035946 Thu, 14 Jul 2011 23:00:00 +0100 5035946 http://www.medworm.com/index.php?rid=5035945&cid=s_32073_162_f&fid=32073&url=http%3A%2F%2Fwww.jlr.org%2Fcgi%2Fcontent%2Fshort%2F52%2F8%2F1533%3Frss%3D1 Human data suggest that reconstituted HDL (rHDL) infusion can induce atherosclerosis regression. Studies in mice indicated that rHDL infusion adversely affects VLDL levels, but this effect is less apparent in humans. This discrepancy may be explained by the fact that humans, in contrast to mice, express cholesteryl ester transfer protein (CETP). The aim of this study was to investigate the role of CETP in the effects of rHDL on VLDL metabolism by using APOE*3-Leiden (E3L) mice, a well-established model for human-like lipoprotein metabolism. At 1 h after injection, rHDL increased plasma VLDL-C and TG in E3L mice, but not in E3L mice cross-bred onto a human CETP background (E3L.CETP mice). This initial raise in VLDL, caused by competition between rHDL and VLDL for LPL-mediated TG hydrolysis,... The Journal of Lipid Research journals http://www.medworm.com/rss/comments.php?id=5035945 Thu, 14 Jul 2011 23:00:00 +0100 5035945 http://www.medworm.com/index.php?rid=5035944&cid=s_32073_162_f&fid=32073&url=http%3A%2F%2Fwww.jlr.org%2Fcgi%2Fcontent%2Fshort%2F52%2F8%2F1526%3Frss%3D1 Mice and humans lacking functional caveolae are dyslipidemic and have reduced fat stores and smaller fat cells. To test the role of caveolins/caveolae in maintaining lipid stores and adipocyte integrity, we compared lipolysis in caveolin-1 (Cav1)-null fat cells to that in cells reconstituted for caveolae by caveolin-1 re-expression. We find that the Cav1-null cells have a modestly enhanced rate of lipolysis and reduced cellular integrity compared with reconstituted cells as determined by the release of lipid metabolites and lactic dehydrogenase, respectively, into the media. There are no apparent differences in the levels of lipolytic enzymes or hormonally stimulated phosphorylation events in the two cell lines. In addition, acute fasting, which dramatically raises circulating fatty acid l... The Journal of Lipid Research journals http://www.medworm.com/rss/comments.php?id=5035944 Thu, 14 Jul 2011 23:00:00 +0100 5035944 http://www.medworm.com/index.php?rid=5035943&cid=s_32073_162_f&fid=32073&url=http%3A%2F%2Fwww.jlr.org%2Fcgi%2Fcontent%2Fshort%2F52%2F8%2F1517%3Frss%3D1 Saturated free fatty acids (FFA) induce hepatocyte lipoapoptosis, a key mediator of liver injury in nonalcoholic fatty liver disease (NAFLD). Lipoapoptosis involves the upregulation of the BH3-only protein PUMA, a potent pro-apoptotic protein. Given that dysregulation of hepatic microRNA expression has been observed in NAFLD, we examined the role of miRNA in regulating PUMA expression during lipotoxicity. By in silico analysis, we identified two putative binding sites for miR-296-5p within the 3' untranslated region (UTR) of PUMA mRNA. Enforced miR-296-5p levels efficiently reduced PUMA protein expression in Huh-7 cells, while antagonism of miR-296-5p function increased PUMA cellular levels. Reporter gene assays identified PUMA 3'UTR as a direct target of miR-296-5p. The saturated FFA, pal... The Journal of Lipid Research journals http://www.medworm.com/rss/comments.php?id=5035943 Thu, 14 Jul 2011 23:00:00 +0100 5035943 http://www.medworm.com/index.php?rid=5035942&cid=s_32073_162_f&fid=32073&url=http%3A%2F%2Fwww.jlr.org%2Fcgi%2Fcontent%2Fshort%2F52%2F8%2F1509%3Frss%3D1 To date, many studies have been conducted using 25-hydroxycholesterol, which is a potent regulator of lipid metabolism. However, the origins of this oxysterol have not been entirely elucidated. Cholesterol 25-hydroxylase is one of the enzymes responsible for the metabolism of 25-hydroxycholesterol, but the expression of this enzyme is very low in humans. This oxysterol is also synthesized by sterol 27-hydroxylase (CYP27A1) and cholesterol 24-hydroxylase(CYP46A1), but it is only a minor product of these enzymes. We now report that CYP3A synthesizes a significant amount of 25-hydroxycholesterol and may participate in the regulation of lipid metabolism. Induction of CYP3A by pregnenolone-16α-carbonitrile caused the accumulation of 25-hydroxycholesterol in a cell line derived from mouse ... The Journal of Lipid Research journals http://www.medworm.com/rss/comments.php?id=5035942 Thu, 14 Jul 2011 23:00:00 +0100 5035942 http://www.medworm.com/index.php?rid=5035941&cid=s_32073_162_f&fid=32073&url=http%3A%2F%2Fwww.jlr.org%2Fcgi%2Fcontent%2Fshort%2F52%2F8%2F1500%3Frss%3D1 In this study, we employed an adipocyte differentiation system from mouse embryonic fibroblasts (MEF) and compared the effects of each PG receptor-deficiency on adipocyte differentiation. In wild-type (WT) MEF cells, inhibition of endogenous PG synthesis by indomethacin augmented the differentiation, whereas exogenous PGE2, as well as an FP agonist, reversed the effect of indomethacin. In EP4-deficient cells, basal differentiation was upregulated to the levels in indomethacin-treated WT cells, and indomethacin did not further enhance differentiation. Differentiation in FP-deficient cells was equivalent to WT and was still sensitive to indomethacin. PGE2 or indomethacin treatment of WT MEF cells for the first two days was enough to suppress or enhance transcription of the Pparg2 gene as wel... The Journal of Lipid Research journals http://www.medworm.com/rss/comments.php?id=5035941 Thu, 14 Jul 2011 23:00:00 +0100 5035941 http://www.medworm.com/index.php?rid=5035940&cid=s_32073_162_f&fid=32073&url=http%3A%2F%2Fwww.jlr.org%2Fcgi%2Fcontent%2Fshort%2F52%2F8%2F1494%3Frss%3D1 This study reveals that this plasma-based assay correlates with liver SCD1 inhibition and can thus have clinical utility. (Source: The Journal of Lipid Research) The Journal of Lipid Research journals http://www.medworm.com/rss/comments.php?id=5035940 Thu, 14 Jul 2011 23:00:00 +0100 5035940 http://www.medworm.com/index.php?rid=5035939&cid=s_32073_162_f&fid=32073&url=http%3A%2F%2Fwww.jlr.org%2Fcgi%2Fcontent%2Fshort%2F52%2F8%2F1483%3Frss%3D1 Accelerated atherosclerosis is the leading cause of death in type 1 diabetes, but the mechanism of type 1 diabetes-accelerated atherosclerosis is not well understood, in part due to the lack of a good animal model for the long-term studies required. In an attempt to create a model for studying diabetic macrovascular disease, we have generated type 1 diabetic Akita mice lacking the low density lipoprotein receptor (Ins2AkitaLdlr–/–). Ins2AkitaLdlr–/– mice were severely hyperglycemic with impaired glucose tolerance. Compared with Ldlr–/– mice, 20-week-old Ins2AkitaLdlr–/– mice fed a 0.02% cholesterol AIN76a diet showed increased plasma triglyceride and cholesterol levels, and increased aortic root cross-sectional atherosclerotic lesion area [22... The Journal of Lipid Research journals http://www.medworm.com/rss/comments.php?id=5035939 Thu, 14 Jul 2011 23:00:00 +0100 5035939 http://www.medworm.com/index.php?rid=5035938&cid=s_32073_162_f&fid=32073&url=http%3A%2F%2Fwww.jlr.org%2Fcgi%2Fcontent%2Fshort%2F52%2F8%2F1471%3Frss%3D1 The ATP binding cassette, class A (ABCA) proteins are homologous polytopic transmembrane transporters that function as lipid pumps at distinct subcellular sites in a variety of cells. Located within the N terminus of these transporters, there exists a highly conserved xLxxKN motif of unknown function. To define its role, human ABCA3 was employed as a primary model representing ABCA transporters, while mouse ABCA1 was utilized to support major findings. Transfection studies showed colocalization of both transporters with surfactant protein C (SP-C), a marker peptide for successful protein targeting to lysosomal-like organelles. In contrast, alanine mutation of xLxxKN resulted in endoplasmic reticulum retention. As proof of principle, swapping xLxxKN for the known lysosomal targeting motif o... The Journal of Lipid Research journals http://www.medworm.com/rss/comments.php?id=5035938 Thu, 14 Jul 2011 23:00:00 +0100 5035938 http://www.medworm.com/index.php?rid=5035937&cid=s_32073_162_f&fid=32073&url=http%3A%2F%2Fwww.jlr.org%2Fcgi%2Fcontent%2Fshort%2F52%2F8%2F1461%3Frss%3D1 Apolipoprotein A-II (apoA-II) is the second major apolipoprotein following apolipoprotein A-I (apoA-I) in HDL. ApoA-II has multiple physiological functions and can form senile amyloid fibrils (AApoAII) in mice. Most circulating apoA-II is present in lipoprotein A-I/A-II. To study the influence of apoA-I on apoA-II and AApoAII amyloidosis, apoA-I-deficient (C57BL/6J.Apoa1–/–) mice were used. Apoa1–/– mice showed the expected significant reduction in total cholesterol (TC), HDL cholesterol (HDL-C), and triglyceride (TG) plasma levels. Unexpectedly, we found that apoA-I deficiency led to redistribution of apoA-II in HDL and an age-related increase in apoA-II levels, accompanied by larger HDL particle size and an age-related increase in TC, HDL-C, and TG. Aggravated AAp... The Journal of Lipid Research journals http://www.medworm.com/rss/comments.php?id=5035937 Thu, 14 Jul 2011 23:00:00 +0100 5035937 http://www.medworm.com/index.php?rid=5035936&cid=s_32073_162_f&fid=32073&url=http%3A%2F%2Fwww.jlr.org%2Fcgi%2Fcontent%2Fshort%2F52%2F8%2F1450%3Frss%3D1 Both insulin and the cell death-inducing DNA fragmentation factor-α-like effector (CIDE) family play important roles in apoptosis and lipid droplet formation. Previously, we reported that CIDEA and CIDEC are differentially regulated by insulin and contribute separately to insulin-induced anti-apoptosis and lipid droplet formation in human adipocytes. However, the upstream signals of CIDE proteins remain unclear. Here, we investigated the signaling molecules involved in insulin regulation of CIDEA and CIDEC expression. The phosphatidylinositol 3-kinase (PI3K) inhibitors wortmannin and PI-103 blocked both insulin-induced downregulation of CIDEA and upregulation of CIDEC. The Akt inhibitor API-2 and the c-Jun N-terminal kinase (JNK) inhibitor SP600125 selectively inhibited insulin regul... The Journal of Lipid Research journals http://www.medworm.com/rss/comments.php?id=5035936 Thu, 14 Jul 2011 23:00:00 +0100 5035936 http://www.medworm.com/index.php?rid=5035935&cid=s_32073_162_f&fid=32073&url=http%3A%2F%2Fwww.jlr.org%2Fcgi%2Fcontent%2Fshort%2F52%2F8%2F1447%3Frss%3D1 (Source: The Journal of Lipid Research) The Journal of Lipid Research journals http://www.medworm.com/rss/comments.php?id=5035935 Thu, 14 Jul 2011 23:00:00 +0100 5035935 http://www.medworm.com/index.php?rid=5007608&cid=s_32073_162_f&fid=32073&url=http%3A%2F%2Fwww.jlr.org%2Fcgi%2Fcontent%2Fshort%2F52%2F7%2F1435%3Frss%3D1 Niemann-Pick type C1 (NPC1) disease is a rare, progressively fatal neurodegenerative disease for which there are no FDA-approved therapies. A major barrier to developing new therapies for this disorder has been the lack of a sensitive and noninvasive diagnostic test. Recently, we demonstrated that two cholesterol oxidation products, specifically cholestane-3β,5α,6β-triol (3β,5α,6β-triol) and 7-ketocholesterol (7-KC), were markedly increased in the plasma of human NPC1 subjects, suggesting a role for these oxysterols in diagnosis of NPC1 disease and evaluation of therapeutics in clinical trials. In the present study, we describe the development of a sensitive and specific LC-MS/MS method for quantifying 3β,5α,6β-triol and 7-KC human plasma aft... The Journal of Lipid Research journals http://www.medworm.com/rss/comments.php?id=5007608 Thu, 09 Jun 2011 23:00:00 +0100 5007608 http://www.medworm.com/index.php?rid=5007607&cid=s_32073_162_f&fid=32073&url=http%3A%2F%2Fwww.jlr.org%2Fcgi%2Fcontent%2Fshort%2F52%2F7%2F1429%3Frss%3D1 This study effectively used OCT to measure the rates at which naturally occurr­ing lipoproteins enter both normal and diseased carotid intimal tissue. (Source: The Journal of Lipid Research) The Journal of Lipid Research journals http://www.medworm.com/rss/comments.php?id=5007607 Thu, 09 Jun 2011 23:00:00 +0100 5007607 http://www.medworm.com/index.php?rid=5007606&cid=s_32073_162_f&fid=32073&url=http%3A%2F%2Fwww.jlr.org%2Fcgi%2Fcontent%2Fshort%2F52%2F7%2F1420%3Frss%3D1 The advantages of using 2H2O to quantify cholesterol synthesis include i) homogeneous precursor labeling, ii) incorporation of 2H via multiple pathways, and iii) the ability to perform long-term studies in free-living subjects. However, there are two concerns. First, the t1/2 of tracer in body water presents a challenge when there is a need to acutely replicate measurements in the same subject. Second, assumptions are made regarding the number of hydrogens (n) that are incorporated during de novo synthesis. Our primary objective was to determine whether a step-based approach could be used to repeatedly study cholesterol synthesis a subject. We observed comparable changes in the 2H-labeling of plasma water and total plasma cholesterol in African-Green monkeys that received five oral doses o... The Journal of Lipid Research journals http://www.medworm.com/rss/comments.php?id=5007606 Thu, 09 Jun 2011 23:00:00 +0100 5007606 http://www.medworm.com/index.php?rid=5007605&cid=s_32073_162_f&fid=32073&url=http%3A%2F%2Fwww.jlr.org%2Fcgi%2Fcontent%2Fshort%2F52%2F7%2F1411%3Frss%3D1 To identify genetic loci influencing blood lipid levels in Caribbean Hispanics, we first conducted a genome-wide linkage scan in 1,211 subjects from 100 Dominican families on five lipid quantitative traits: total cholesterol (TC), low density lipoprotein cholesterol (LDL-C), high density lipoprotein cholesterol (HDL-C), triglycerides (TG), and LDL-C/HDL-C ratio. We then investigated the association between blood lipid levels and 21,361 single nucleotide polymorphisms (SNP) under the 1-logarithm of odds (LOD) unit down regions of linkage peaks in an independent community-based subcohort (N = 814, 42% Dominican) from the Northern Manhattan Study (NOMAS). We found significant linkage evidence for LDL-C/HDL-C on 7p12 (multipoint LOD = 3.91) and for TC on 16q23 (LOD = 3.35). In addition, we ide... The Journal of Lipid Research journals http://www.medworm.com/rss/comments.php?id=5007605 Thu, 09 Jun 2011 23:00:00 +0100 5007605 http://www.medworm.com/index.php?rid=5007604&cid=s_32073_162_f&fid=32073&url=http%3A%2F%2Fwww.jlr.org%2Fcgi%2Fcontent%2Fshort%2F52%2F7%2F1400%3Frss%3D1 We examined the roles that NPC1/2 proteins play in the intracellular trafficking of tocopherol. Reduction of NPC1 or NPC2 expression or function in cultured cells caused a marked lysosomal accumulation of vitamin E in cultured cells. In vivo, tocopherol significantly accumulated in murine Npc1-null and Npc2-null livers, Npc2-null cerebella, and Npc1-null cerebral cortices. Plasma tocopherol levels were within the normal range in Npc1-null and Npc2-null mice, and in plasma samples from human NPC patients. The binding affinity of tocopherol to the purified sterol-binding domain of NPC1 and to purified NPC2 was significantly weaker than that of cholesterol (measurements kindly performed by R. Infante, University of Texas Southwestern Medical Center, Dallas, TX). Taken together, our observatio... The Journal of Lipid Research journals http://www.medworm.com/rss/comments.php?id=5007604 Thu, 09 Jun 2011 23:00:00 +0100 5007604 http://www.medworm.com/index.php?rid=5007603&cid=s_32073_162_f&fid=32073&url=http%3A%2F%2Fwww.jlr.org%2Fcgi%2Fcontent%2Fshort%2F52%2F7%2F1392%3Frss%3D1 Glucosylceramide synthase (GlcT-1) catalyzes the synthesis of glucosylceramide (GlcCer), the core structure of major glycosphingolipids (GSLs). Obesity is a metabolic disorder caused by an imbalance between energy uptake and expenditure, resulting in excess stored body fat. Recent studies have shown that GSL levels are increased in obese rodents and that pharmacologically reducing GSL levels by inhibiting GlcCer synthesis improves adipocyte function. However, the molecular mechanism underlying these processes is still not clearly understood. Using Drosophila as a model animal, we report that GlcT-1 expression in the fat body, which is equivalent to mammalian adipose tissue, regulates energy metabolism. Overexpression of GlcT-1 increases stored nutrition (triacylglycerol and carbohydrate) l... The Journal of Lipid Research journals http://www.medworm.com/rss/comments.php?id=5007603 Thu, 09 Jun 2011 23:00:00 +0100 5007603 http://www.medworm.com/index.php?rid=5007602&cid=s_32073_162_f&fid=32073&url=http%3A%2F%2Fwww.jlr.org%2Fcgi%2Fcontent%2Fshort%2F52%2F7%2F1383%3Frss%3D1 Proprotein convertase subtilisin/kexin type 9 (PCSK9) plays a major role in cholesterol homeostasis through enhanced degradation of the LDL receptor (LDLR) in liver. As novel inhibitors/silencers of PCSK9 are now being tested in clinical trials to treat hypercholesterolemia, it is crucial to define the physiological consequences of the lack of PCSK9 in various organs. LDLR regulation by PCSK9 has not been extensively described during mouse brain development and injury. Herein, we show that PCSK9 and LDLR are co-expressed in mouse brain during development and at adulthood. Although the protein levels of LDLR and apolipoprotein E (apoE) in the adult brain of Pcsk9–/– mice are similar to those of wild-type (WT) mice, LDLR levels increased and were accompanied by a reduction of apo... The Journal of Lipid Research journals http://www.medworm.com/rss/comments.php?id=5007602 Thu, 09 Jun 2011 23:00:00 +0100 5007602 http://www.medworm.com/index.php?rid=5007601&cid=s_32073_162_f&fid=32073&url=http%3A%2F%2Fwww.jlr.org%2Fcgi%2Fcontent%2Fshort%2F52%2F7%2F1373%3Frss%3D1 Abstract We evaluated the biological basis of reduced fat gain by oleoylethanolamide (OEA) in high-fat-fed mice and sought to determine how degradation of OEA affected its efficiency by comparing its effects to those of KDS-5104, a nonhydrolyzable lipid OEA analog. Mice were given OEA or KDS-5104 by the oral route (100 mg/kg body weight). Sixty-eight variables per mouse, describing six biological processes (lipid transport, lipogenesis, energy intake, energy expenditure, endocannabinoid signaling, and glucose metabolism), spanning gene expression of biochemical and physiological parameters were examined to determine the primary target whereby OEA reduces fat gain. Although KDS-5104 but not OEA was resistant to fatty acid amide hydrolase hydrolysis, OEA was degraded by an unidentified hydro... The Journal of Lipid Research journals http://www.medworm.com/rss/comments.php?id=5007601 Thu, 09 Jun 2011 23:00:00 +0100 5007601 http://www.medworm.com/index.php?rid=5007600&cid=s_32073_162_f&fid=32073&url=http%3A%2F%2Fwww.jlr.org%2Fcgi%2Fcontent%2Fshort%2F52%2F7%2F1363%3Frss%3D1 In this study, we investigated the role of positively and negatively charged amino acids within the 89-99 region of apolipoprotein A-I (apoA-I), which are highly conserved in mammals, on plasma lipid homeostasis and the biogenesis of HDL. We previously showed that deletion of the 89-99 region of apoA-I increased plasma cholesterol and phospholipids, but it did not affect plasma triglycerides. Functional studies using adenovirus-mediated gene transfer of two apoA-I mutants in apoA-I-deficient mice showed that apoA-I[D89A/E91A/E92A] increased plasma cholesterol and caused severe hypertriglyceridemia. HDL levels were reduced, and approximately 40% of the apoA-I was distributed in VLDL/IDL. The HDL consisted of mostly spherical and a few discoidal particles and contained preβ1 and α... The Journal of Lipid Research journals http://www.medworm.com/rss/comments.php?id=5007600 Thu, 09 Jun 2011 23:00:00 +0100 5007600 http://www.medworm.com/index.php?rid=5007599&cid=s_32073_162_f&fid=32073&url=http%3A%2F%2Fwww.jlr.org%2Fcgi%2Fcontent%2Fshort%2F52%2F7%2F1352%3Frss%3D1 In this study, the role of Pck1 in mammary gland epithelial cells was analyzed. The developmental expression of Pck1 decreased in isolated mouse mammary gland epithelial cells through development and during lactation. Using HC11, a clonal mammary epithelial cell line, we found that both Janus kinase 2 signal transducers and activators of transcription 5 and the AKT pathways contributed to the repression of Pck1 mRNA by prolactin. These pathways necessitate three accessory factor regions of the Pck1 promoter for repression by prolactin. Using [U-13C6]glucose, [U-13C3]pyruvate, and [U-13C3]glycerol in HC11 cells, we determined that Pck1 functions in the pathway for the conversion of gluconeogenic precursors to glucose and contributes to glycerol-3-phosphate synthesis through glyceroneogenesi... The Journal of Lipid Research journals http://www.medworm.com/rss/comments.php?id=5007599 Thu, 09 Jun 2011 23:00:00 +0100 5007599 http://www.medworm.com/index.php?rid=5007598&cid=s_32073_162_f&fid=32073&url=http%3A%2F%2Fwww.jlr.org%2Fcgi%2Fcontent%2Fshort%2F52%2F7%2F1345%3Frss%3D1 Filipin is an antibiotic polyene widely used as a histochemical marker for cholesterol. We previously reported cholesterol/filipin-positive staining in brain of β-galactosidase (β-gal) knockout (–/–) mice (GM1 gangliosidosis). The content and distribution of cholesterol and gangliosides was analyzed in plasma membrane (PM) and microsomal (MS) fractions from whole-brain tissue of 15 week-old control (β-gal+/–) and GM1 gangliosidosis (β-gal–/–) mice. Total ganglioside content (µg sialic acid/mg protein) was 3-fold and 7-fold greater in the PM and MS fractions, respectively, in βgal–/– mice than in βgal+/– mice. GM1 content was 30-fold and 50-fold greater in the PM and MS fractions, respectively. In contrast, ... The Journal of Lipid Research journals http://www.medworm.com/rss/comments.php?id=5007598 Thu, 09 Jun 2011 23:00:00 +0100 5007598 http://www.medworm.com/index.php?rid=5007597&cid=s_32073_162_f&fid=32073&url=http%3A%2F%2Fwww.jlr.org%2Fcgi%2Fcontent%2Fshort%2F52%2F7%2F1328%3Frss%3D1 Abstract Niemann-Pick disease, type C (NP-C), often associated with Niemann-Pick disease, type C1 (NPC1) mu­tations, is a cholesterol-storage disorder characterized by cellular lipid accumulation, neurodegeneration, and reduced steroid production. To study NPC1 function in vivo, we cloned zebrafish npc1 and analyzed its gene expression and activity by reducing Npc1 protein with morpholino (MO)-oligonucleotides. Filipin staining in npc1-morphant cells was punctate, suggesting abnormal accumulation of cholesterol. Developmentally, reducing Npc1 did not disrupt early cell fate or survival; however, early morphogenetic movements were delayed, and the actin cytoskeleton network was abnormal. MO-induced defects were rescued with ectopic expression of mouse NPC1, demonstrating functional gene... The Journal of Lipid Research journals http://www.medworm.com/rss/comments.php?id=5007597 Thu, 09 Jun 2011 23:00:00 +0100 5007597 http://www.medworm.com/index.php?rid=5007596&cid=s_32073_162_f&fid=32073&url=http%3A%2F%2Fwww.jlr.org%2Fcgi%2Fcontent%2Fshort%2F52%2F7%2F1319%3Frss%3D1 Abstract Chronic exposure to saturated fatty acids can cause insulin resistance. However, the acute effects of fatty acids are not clear and need to be elucidated because plasma fatty acid concentrations fluctuate postprandially. Here, we present the acute effects of palmitate (PA) on skeletal muscle cells and their underlying molecular mechanisms. Immuno­fluorescence results showed that PA rapidly induced GLUT4 translocation and stimulated glucose uptake in rat skeletal muscle cell line L6. Phosphorylation of AMP-activated protein kinase (AMPK), Akt, and extracellular signal-related kinase1/2 (ERK1/2) was enhanced by PA in a time-dependent manner. Cell surface-bound PA was sufficient to stimulate Akt phosphorylation. The inhibitors of PI3 kinase (PI3K), AMPK, Akt, and ERK1/2 coul... The Journal of Lipid Research journals http://www.medworm.com/rss/comments.php?id=5007596 Thu, 09 Jun 2011 23:00:00 +0100 5007596 http://www.medworm.com/index.php?rid=5007595&cid=s_32073_162_f&fid=32073&url=http%3A%2F%2Fwww.jlr.org%2Fcgi%2Fcontent%2Fshort%2F52%2F7%2F1307%3Frss%3D1 We report that 1) LPA injection into the air pouch induced leukocyte recruitment and that both LPA1 and LPA3 were involved in this process; 2) LPA stimulated the release of the pro-inflammatory chemokines keratinocyte-derived chemokine (KC) and interferon-inducible protein-10 (IP-10) in the air pouch; 3) tumor necrosis factor-α (TNF-α) injected into the air pouch prior to LPA strongly potentiated LPA-mediated secretion of cytokines/chemokines, including KC, IL-6, and IP-10, which preceded the enhanced leukocyte influx; and 4) blocking CXCR2 significantly reduced leukocyte infiltration. We suggest that LPA, via LPA1 and LPA3 receptors, may play a significant role in inducing and/or sustaining the massive infiltration of leukocytes during inflammation. (Source: The Journal of Lip... The Journal of Lipid Research journals http://www.medworm.com/rss/comments.php?id=5007595 Thu, 09 Jun 2011 23:00:00 +0100 5007595 http://www.medworm.com/index.php?rid=5007594&cid=s_32073_162_f&fid=32073&url=http%3A%2F%2Fwww.jlr.org%2Fcgi%2Fcontent%2Fshort%2F52%2F7%2F1305%3Frss%3D1 (Source: The Journal of Lipid Research) The Journal of Lipid Research journals http://www.medworm.com/rss/comments.php?id=5007594 Thu, 09 Jun 2011 23:00:00 +0100 5007594 http://www.medworm.com/index.php?rid=4820459&cid=s_32073_162_f&fid=32073&url=http%3A%2F%2Fwww.jlr.org%2Fcgi%2Fcontent%2Fshort%2F52%2F6%2F1303%3Frss%3D1 (Source: The Journal of Lipid Research) The Journal of Lipid Research journals http://www.medworm.com/rss/comments.php?id=4820459 Thu, 12 May 2011 23:00:00 +0100 4820459 http://www.medworm.com/index.php?rid=4820458&cid=s_32073_162_f&fid=32073&url=http%3A%2F%2Fwww.jlr.org%2Fcgi%2Fcontent%2Fshort%2F52%2F6%2F1294%3Frss%3D1 Ceramides play a crucial role in divergent signaling events, including differentiation, senescence, proliferation, and apoptosis. Ceramides are a minor lipid component in terms of content; thus, highly sensitive detection is required for accurate quantification. The recently developed isobaric tags for relative and absolute quantitation (iTRAQ) method enables a precise comparison of both protein and aminophospholipids. However, iTRAQ tagging had not been applied to the determination of sphingolipids. Here we report a method for the simultaneous measurement of multiple ceramide and monohexosylceramide samples using iTRAQ tags. Samples were hydrolyzed with sphingolipid ceramide N-deacylase (SCDase) to expose the free amino group of the sphingolipids, to which the N-hydroxysuccinimide group o... The Journal of Lipid Research journals http://www.medworm.com/rss/comments.php?id=4820458 Thu, 12 May 2011 23:00:00 +0100 4820458 http://www.medworm.com/index.php?rid=4820457&cid=s_32073_162_f&fid=32073&url=http%3A%2F%2Fwww.jlr.org%2Fcgi%2Fcontent%2Fshort%2F52%2F6%2F1281%3Frss%3D1 The proportions of body fat and fat-free mass are determining factors of adiposity-associated diseases. Work in Caenorhabditis elegans has revealed evolutionarily conserved pathways of fat metabolism. Nevertheless, analysis of body composition and fat distribution in the nematodes has only been partially unraveled because of methodological difficulties. We characterized metabolic C. elegans mutants by using novel and feasible BODIPY 493/503-based fat staining and flow cytometry approaches. Fixative as well as vital BODIPY staining procedures visualize major fat stores, preserve native lipid droplet morphology, and allow quantification of fat content per body volume of individual worms. Colocalization studies using coherent anti-Stokes Raman scattering microscopy, Raman microspectroscopy, a... The Journal of Lipid Research journals http://www.medworm.com/rss/comments.php?id=4820457 Thu, 12 May 2011 23:00:00 +0100 4820457 http://www.medworm.com/index.php?rid=4820456&cid=s_32073_162_f&fid=32073&url=http%3A%2F%2Fwww.jlr.org%2Fcgi%2Fcontent%2Fshort%2F52%2F6%2F1272%3Frss%3D1 Recognition of the strength of nonhuman primate models in investigating metabolic disorders has resulted in an expanded need for in vivo research techniques. We studied adipose metabolism in 10 baboons (13.0 ± 4.2 years old, 29.5 ± 5.5 kg). Part 1 evaluated the effect of different sedatives on the rate of appearance of plasma free fatty acids (RaFFA), assessed using 13C4-labeled palmitate infusion (7 µmol/kg/min). Animals, were studied with no sedation, with complete isoflurane sedation, and with minimal midazolam infusion (0.04 mg/kg/h), with the last scheme allowing for the most consistent values and animals that were visually more calm. In Part 2, RaFFA and RaGlycerol (D5-glycerol, 5 mg/kg lean body mass/h) were measured. From midnight to 0300, flux fell and came to ... The Journal of Lipid Research journals http://www.medworm.com/rss/comments.php?id=4820456 Thu, 12 May 2011 23:00:00 +0100 4820456 http://www.medworm.com/index.php?rid=4820455&cid=s_32073_162_f&fid=32073&url=http%3A%2F%2Fwww.jlr.org%2Fcgi%2Fcontent%2Fshort%2F52%2F6%2F1265%3Frss%3D1 Apolipoprotein CIII (apoCIII), a major constituent of triglyceride-rich lipoprotein, has been proposed as a key contributor to hypertriglyceridemia on the basis of its inhibitory effects on lipoprotein lipase. Many immunochemical methods have been developed for human apoCIII quantification, including ELISA. However, a sensitive and quantitative assay for nonhuman primates is not commercially available. We developed a sensitive, quantitative, and highly specific sandwich ELISA to measure apoCIII in both nonhuman primate and human serum. Our assay generates a linear calibration curve from 0.01 µg/ml to 10 µg/ml using an apoCIII standard that was purified from cynomolgus monkey serum. It is highly reproducible (intra- and interplate CV < 5% and < 8%, respectively), sensitive... The Journal of Lipid Research journals http://www.medworm.com/rss/comments.php?id=4820455 Thu, 12 May 2011 23:00:00 +0100 4820455 http://www.medworm.com/index.php?rid=4820454&cid=s_32073_162_f&fid=32073&url=http%3A%2F%2Fwww.jlr.org%2Fcgi%2Fcontent%2Fshort%2F52%2F6%2F1256%3Frss%3D1 Phytosterols (plant sterols and stanols) can lower intestinal cholesterol absorption, but the complex dynamics of the lipid digestion process in the presence of phytosterol esters (PEs) are not fully understood. We performed a clinical experiment in intubated healthy subjects to study the time course of changes in the distribution of all lipid moieties present in duodenal phases during 4 h of digestion of meals with 3.2 g PE (PE meal) or without (control meal) PE. In vitro experiments under simulated gastrointestinal conditions were also performed. The addition of PE did not alter triglyceride (TG) hydrolysis in the duodenum or subsequent chylomicron TG occurrence in the circulation. In contrast, cholesterol accumulation in the duodenum aqueous phase was markedly reduced in the presence of... The Journal of Lipid Research journals http://www.medworm.com/rss/comments.php?id=4820454 Thu, 12 May 2011 23:00:00 +0100 4820454 http://www.medworm.com/index.php?rid=4820453&cid=s_32073_162_f&fid=32073&url=http%3A%2F%2Fwww.jlr.org%2Fcgi%2Fcontent%2Fshort%2F52%2F6%2F1247%3Frss%3D1 Autotaxin (ATX) is a secreted lysophospholipase D that generates the lipid mediator lysophosphatidic acid (LPA). ATX is secreted by adipose tissue and its expression is enhanced in obese/insulin-resistant individuals. Here, we analyzed the specific contribution of adipose-ATX to fat expansion associated with nutritional obesity and its consequences on plasma LPA levels. We established ATXF/F/aP2-Cre (FATX-KO) transgenic mice carrying a null ATX allele specifically in adipose tissue. FATX-KO mice and their control littermates were fed either a normal or a high-fat diet (HFD) (45% fat) for 13 weeks. FATX-KO mice showed a strong decrease (up to 90%) in ATX expression in white and brown adipose tissue, but not in other ATX-expressing organs. This was associated with a 38% reduction in plasma L... The Journal of Lipid Research journals http://www.medworm.com/rss/comments.php?id=4820453 Thu, 12 May 2011 23:00:00 +0100 4820453 http://www.medworm.com/index.php?rid=4820452&cid=s_32073_162_f&fid=32073&url=http%3A%2F%2Fwww.jlr.org%2Fcgi%2Fcontent%2Fshort%2F52%2F6%2F1234%3Frss%3D1 The mechanism of FFA-induced insulin resistance is not fully understood. We have searched for effector molecules(s) in FFA-induced insulin resistance. Palmitic acid (PA) but not oleic acid (OA) induced insulin resistance in L6 myotubes through C-Jun N-terminal kinase (JNK) and insulin receptor substrate 1 (IRS-1) Ser307 phosphorylation. Inhibitors of ceramide synthesis did not block insulin resistance by PA. However, inhibition of the conversion of PA to lysophosphatidylcholine (LPC) by calcium-independent phospholipase A2 (iPLA2) inhibitors, such as bromoenol lactone (BEL) or palmitoyl trifluoromethyl ketone (PACOCF3), prevented insulin resistance by PA. iPLA2 inhibitors or iPLA2 small interfering RNA (siRNA) attenuated JNK or IRS-1 Ser307 phosphorylation by PA. PA treatment increased LPC... The Journal of Lipid Research journals http://www.medworm.com/rss/comments.php?id=4820452 Thu, 12 May 2011 23:00:00 +0100 4820452 http://www.medworm.com/index.php?rid=4820451&cid=s_32073_162_f&fid=32073&url=http%3A%2F%2Fwww.jlr.org%2Fcgi%2Fcontent%2Fshort%2F52%2F6%2F1222%3Frss%3D1 We report here the identification and complete characterization of a novel oxysterol, 3β,5α-dihydroxycholest-7-en-6-one (DHCEO), as a biomarker for 7-DHC oxidation in fibroblasts from SLOS patients and brain tissue from a SLOS mouse model. Deuterated (d7)-standards of 7-DHC and DHCEO were synthesized from d7-cholesterol. The presence of DHCEO in SLOS samples was supported by chemical derivatization in the presence of d7-DHCEO standard followed by HPLC-MS or GC-MS analysis. Quantification of cholesterol, 7-DHC, and DHCEO was carried out by isotope dilution MS with the d7-standards. The level of DHCEO was high and correlated well with the level of 7-DHC in all samples examined (R = 0.9851). Based on our in vitro studies in two different cell lines, the mechanism of formation of DH... The Journal of Lipid Research journals http://www.medworm.com/rss/comments.php?id=4820451 Thu, 12 May 2011 23:00:00 +0100 4820451 http://www.medworm.com/index.php?rid=4820450&cid=s_32073_162_f&fid=32073&url=http%3A%2F%2Fwww.jlr.org%2Fcgi%2Fcontent%2Fshort%2F52%2F6%2F1211%3Frss%3D1 Ceramides (CERs) in the upper layer of the skin, the stratum corneum (SC), play a key role in the skin barrier function. In human SC, the literature currently reports 11 CER subclasses that have been identified. In this paper, a novel quick and robust LC/MS method is presented that allows the separation and analysis of all known human SC CER subclasses using only limited sample preparation. Besides all 11 known and identified subclasses, a 3D multi-mass chromatogram shows the presence of other lipid subclasses. Using LC/MS/MS with an ion trap (IT) system, a Fourier transform-ion cyclotron resonance system, and a triple quadrupole system, we were able to identify one of these lipid subclasses as a new CER subclass: the ester-linked -hydroxy fatty acid with a dihydrosphingosine base (CER [EO... The Journal of Lipid Research journals http://www.medworm.com/rss/comments.php?id=4820450 Thu, 12 May 2011 23:00:00 +0100 4820450 http://www.medworm.com/index.php?rid=4820449&cid=s_32073_162_f&fid=32073&url=http%3A%2F%2Fwww.jlr.org%2Fcgi%2Fcontent%2Fshort%2F52%2F6%2F1200%3Frss%3D1 To determine if the dose of peptide administered or the plasma level was more important, doses of 0.15, 0.45, 4.5, or 45 mg/kg/day of the peptide D-4F were administered orally or subcutaneously (SQ) to apoliptotein (apo)E null mice. Plasma levels of peptide were ~1,000-fold higher when administered SQ compared with orally. Regardless of the route of administration, doses of 4.5 and 45 mg/kg significantly reduced plasma serum amyloid A (SAA) levels and the HDL inflammatory index (P < 0.0001); doses of 0.15 or 0.45 mg/kg did not. A dose of 45 mg/kg/day administered to apoE null mice on a Western diet reduced aortic atherosclerosis by ~50% (P < 0.0009) whether administered orally or SQ and also significantly reduced plasma levels of SAA (P < 0.002) and lysophosphatidic acid (P < 0... The Journal of Lipid Research journals http://www.medworm.com/rss/comments.php?id=4820449 Thu, 12 May 2011 23:00:00 +0100 4820449