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Mutations in Dyrk1b are associated with metabolic syndrome and nonalcoholic fatty liver disease in humans. Our investigations showed that DYRK1B levels are increased in the liver of patients with nonalcoholic steatohepatitis (NASH) and in mice fed with a high-fat, high-sucrose diet. Increasing Dyrk1b levels in the mouse liver enhanced de novo lipogenesis (DNL), fatty acid uptake, and triacylglycerol secretion and caused NASH and hyperlipidemia. Conversely, knockdown of Dyrk1b was protective against high-calorie-induced hepatic steatosis and fibrosis and hyperlipidemia. Mechanistically, Dyrk1b increased DNL by activating mTORC2 in a kinase-independent fashion. Accordingly, the Dyrk1b-induced NASH was fully rescued when mTORC2 was genetically disrupted. The elevated DNL was associated with increased plasma membrane sn-1,2-diacylglyerol levels and increased PKC[epsilon]-mediated IRK T1150 phosphorylation, which resulted in impaired activation of hepatic insulin signaling and reduced hepatic glycogen storage. These findings provide insights into the mechanisms that underlie Dyrk1binduced hepatic lipogenesis and hepatic insulin resistance and identify Dyrk1b as a therapeutic target for NASH and insulin resistance in the liver., Introduction Nonalcoholic fatty liver disease (NAFLD) is a rapidly growing disorder affecting nearly 25% of the adult population worldwide and is a major risk factor for nonalcoholic steatohepatitis (NASH), atherosclerosis, [...]

The crystal structure of the MraY enzyme from Aquifex aeolicus in complex with the naturally occurring nucleoside inhibitor muraymycin D2 (MD2) reveals that MraY undergoes a large conformational rearrangement near the active site after the binding of MD2, leading to the generation of a nucleoside-binding pocket and a peptide-binding site. Structure of an antibiotic target Peptidoglycan biosynthesis is a well-established target for antibiotics. The first step in this process is catalysed by MraY, for which many naturally occurring inhibitors exist, but the design of new compounds to target this enzyme has been hampered by a lack of structural insight into the mode of inhibition. Here, Seok-Yong Lee and colleagues solve the crystal structure of MraY from the hyperthermophilic bacterium Aquifex aeolicus in complex with the naturally occurring nucleoside inhibitor, muraymycin D2 (MD2). The structure shows that MraY undergoes large conformational rearrangements near the active site following MD2 binding, leading to the generation of a nucleoside-binding pocket and a peptide-binding site. Antibiotic-resistant bacterial infection is a serious threat to public health. Peptidoglycan biosynthesis is a well-established target for antibiotic development. MraY (phospho-MurNAc-pentapeptide translocase) catalyses the first and an essential membrane step of peptidoglycan biosynthesis. It is considered a very promising target for the development of new antibiotics, as many naturally occurring nucleoside inhibitors with antibacterial activity target this enzyme.sup.1,2,3,4. However, antibiotics targeting MraY have not been developed for clinical use, mainly owing to a lack of structural insight into inhibition of this enzyme. Here we present the crystal structure of MraY from Aquifex aeolicus (MraY.sub.AA) in complex with its naturally occurring inhibitor, muraymycin D2 (MD2). We show that after binding MD2, MraY.sub.AA undergoes remarkably large conformational rearrangements near the active site, which lead to the formation of a nucleoside-binding pocket and a peptide-binding site. MD2 binds the nucleoside-binding pocket like a two-pronged plug inserting into a socket. Further interactions it makes in the adjacent peptide-binding site anchor MD2 to and enhance its affinity for MraY.sub.AA. Surprisingly, MD2 does not interact with three acidic residues or the Mg.sup.2+ cofactor required for catalysis, suggesting that MD2 binds to MraY.sub.AA in a manner that overlaps with, but is distinct from, its natural substrate, UDP-MurNAc-pentapeptide. We have determined the principles of MD2 binding to MraY.sub.AA, including how it avoids the need for pyrophosphate and sugar moieties, which are essential features for substrate binding. The conformational plasticity of MraY could be the reason that it is the target of many structurally distinct inhibitors. These findings can inform the design of new inhibitors targeting MraY as well as its paralogues, WecA and TarO., Author(s): Ben C. Chung [sup.1] , Ellene H. Mashalidis [sup.1] , Tetsuya Tanino [sup.2] , Mijung Kim [sup.3] , Akira Matsuda [sup.2] , Jiyong Hong [sup.3] , Satoshi Ichikawa [sup.2] [...]

Cellular lipid metabolism has been linked to Immune responses; however, the precise mechanisms by which de novo fatty add synthesis can regulate inflammatory responses remain unclear. The NLRP3 inflammasome serves as a platform for caspase-1-dependent maturation and secretion of proinflammatory cytokines. Here, we demonstrated that the mitochondrial uncoupling protein-2 (UCP2) regulates NLRP3-mediated caspase-1 activation through the stimulation of lipid synthesis in macrophages. UCP2-deficient mice displayed improved survival in a mouse model of polymicrobial sepsis. Moreover, UCP2 expression was increased in human sepsis. Consistently, UCP2-deficient mice displayed impaired lipid synthesis and decreased production of IL-1β and IL-18 in response to LPS challenge. In macrophages, UCP2 deficiency suppressed NLRP3-mediated caspase-1 activation and NLRP3 expression associated with inhibition of lipid synthesis. In UCP2- deficient macrophages, inhibition of lipid synthesis resulted from the downregulation of fatty acid synthase (FASN), a key regulator of fatty acid synthesis. FASN inhibition by shRNA and treatment with the chemical inhibitors C75 and cerulenin suppressed NLRP3-mediated caspase-1 activation and inhibited NLRP3 and pro-IL-1β gene expression in macrophages. In conclusion, our results suggest that UCP2 regulates the NLRP3 inflammasome by inducing the lipid synthesis pathway in macrophages. These results identify UCP2 as a potential therapeutic target in inflammatory diseases such as sepsis., Introduction Sepsis remains the leading cause of death in the medical intensive care unit (MICU) (1). Although inflammatory responses are important for host defense against invading microbes, excessive inflammation in [...]

The obesity epidemic has led to an increased incidence of nonalcoholic fatty liver disease (NAFLD) and type 2 diabetes. AMP-activated protein kinase (Ampk) regulates energy homeostasis and is activated by [...]

A suite of characteristics is often used to assess egg quality as these properties potentially play important roles in progeny survival and growth. Our objective was to assess egg characteristics including lipid biocomposition of an iteroparous, batch-spawning teleost of wild origin. Maternal allocation to egg number was generally dome-shaped (5 of 8 females) and egg size declined over the breeding season for eight breeding pairs of wild Atlantic cod (Gadus morhua)(n = 43 batches). Egg lipid composition ranged considerably among females and between egg batches within females (e.g., phospholipids 40-86 %; polar 47-87 % and neutral lipids 15-52 % of total lipids; polyunsaturated fatty acids 16-50 % of total fatty acids). Principal component analyses revealed significant interrelationships among maternal traits, batch sequence and fecundity, and egg size and composition. Seasonal trends with regard to lipid deposition were variable; three females showed consistent declines in lipid parameters (µg [egg.sup.-1]) with both batch number and egg diameter, one female showed consistent increase and the four remaining females showed no trend. The three females that exhibited seasonal declines in egg lipid content were characterized as having high fertilization success (>75 %). Our findings highlight the variability in lipid allocation to eggs of batch spawners of wild origin and characterize the composition of endogenous reserves available during embryogenesis and yolk sac larval stages., Introduction In fishes, egg quality is a term coined to describe the overall health of an egg and the impact it has on fertility, embryo survival, hatching success, and subsequent [...]

The failure of pancreatic βcells to adapt to an increasing demand for insulin is the major mechanism by which patients progress from insulin resistance to type 2 diabetes (T2D) and is thought to be related to dysfunctional lipid homeostasis within those cells. In multiple animal models of diabetes, females demonstrate relative protection from βcell failure. We previously found that the hormone 17β-estradiol (E2) in part mediates this benefit. Here, we show that treating male Zucker diabetic fatty (ZDF) rats with E2 suppressed synthesis and accumulation of fatty acids and glycerolipids in islets and protected against βcell failure. The antilipogenic actions of E2 were recapitulated by pharmacological activation of estrogen receptor α (ERα) or ERβin a rat βcell line and in cultured ZDF rat, mouse, and human islets. Pancreas-specific null deletion of ERαin mice [(PERα.sup.-/-]) prevented reduction of lipid synthesis by E2 via a direct action in islets, and [PERα.sup.-/-] mice were predisposed to islet lipid accumulation and βcell dysfunction in response to feeding with a high-fat diet. ER activation inhibited βcell lipid synthesis by suppressing the expression (and activity) of fatty acid synthase via a nonclassical pathway dependent on activated Stat3. Accordingly, pancreas-specific deletion of Stat3 in mice curtailed ER-mediated suppression of lipid synthesis. These data suggest that extranuclear ERs may be promising therapeutic targets to prevent βcell failure in T2D., Introduction Type 2 diabetes (T2D) occurs when pancreatic βcells fail to compensate for the increased insulin demand in the context of obesity-associated insulin resistance. Thus, developing novel therapeutic strategies to [...]

Mass spectrometry imaging of tissue-lipid transfers without MALDI matrix is demonstrated. Commercially available nanostructured surfaces (nano-assisted laser desorption-ionization or NALDI) are used as substrates for imprinting of tissue sections. The lithographic transfers are then washed and the two-dimensional distribution of the lipids is imaged by laser desorption-ionization mass spectrometry. The NALDI imaging of lipid transfers is compared with standard MALDI imaging of matrix-coated tissue sections. The obtained images are of the same quality, and no spatial information is lost due to the imprinting process. NALDI imaging is faster due to the absence of the time-consuming matrix deposition step, and the NALDI mass spectra are less complex and easier to interpret than standard MALDI. In this particular application example, NALDI mass spectrometry is able to identify the same lipid species as MALDI mass spectrometry and provides better distinction between kidney and adrenal gland tissues based on the lipid analysis. 10.1021/ac100661h

Evolutionary loss of traits can result from negative selection on a specific phenotype, or if the trait is selectively neutral, because the phenotype associated with the trait has become redundant. Even essential traits may be lost, however, if the resulting phenotypic deficiencies can be compensated for by the environment or a symbiotic partner. Here we demonstrate that loss of an essential metabolic trait in parasitic wasps has evolved through environmental compensation. We tested 24 species for the ability to synthesize lipids de novo and collected additional data from the literature. We found the majority of adult parasitoid species to be incapable of synthesizing lipids, and phylogenetic analyses showed that the evolution of lack of lipogenesis is concurrent with that of parasitism in insects. Exploitive host manipulation, in which the host is forced to synthesize lipids to the benefit of the parasitoid, presumably facilitates loss of lipogenesis through environmental compensation. Lipogenesis re-evolved in a small number of parasitoid species, particularly host generalists. The wide range of host species in which generalists are able to develop may impede effective host manipulation and could have resulted in regaining of lipogenic ability in generalist parasitoids. As trait loss through environmental compensation is unnoticed at the phenotypic level, it may be more common than currently anticipated, especially in species involved in intricate symbiotic relationships with other species. coevolution | environmental compensation | fat reserves | host manipulation | parasitoids doi/10.1073/pnas.1001744107

Higher concentrations of circulating lipids (cholesterol and triglycerides) and their decreased catabolism pose a major risk in the development of atherosclerosis and coronary heart disease (CHD). Although statins are widely used for treatment of hyperlipidemia, side effects associated with their use have prompted the search for a safer alternative for treating hyperlipidemia. The present study investigated the effect of water-soluble compounds in Abana (WSCA), a polyherbal drug formulation traditionally used in India for the treatment of hyperlipidemia, on lipid metabolism in Hep[G.sub.2] cells. WSCA reduced cholesterol and triglyceride content in the cells and their supernatant. WSCA inhibited the incorporation of [2-[sup.14]C]acetate into cellular cholesterol and fatty acids, suggesting the inhibition of lipid synthesis. In addition, WSCA inhibited HMG-CoA reductase, a key metabolic enzyme involved in the biosynthesis of cholesterol. WSCA also increased cholesterol and fatty acid secretion into the cell supernatant, suggesting the enhanced removal of cholesterol and fatty acids. Furthermore, WSCA showed decreased linoleic acid (18:2) and arachidonic acid (20:4) content in Hep[G.sub.2] cells. The present study is the first to show that WSCA simultaneously inhibited cellular cholesterol biosynthesis and increased cholesterol secretion into the cell supernatant in Hep[G.sub.2] cells. Key words: Abana, cholesterol, triglyceride, fatty acid, HMG-CoA, cholesterol efflux. L'augmentation des concentrations de lipides circulants (cholesterol et triglycerides) et la diminution de leur catabolisme representent un risque majeur de deeveloppement d'atheerosclerose et de maladie coronarienne. Les statines sont couramment utilisees dans le traitement de l'hyperlipidemie, mais leur effet deletere sur la sante a encourage; la recherche d'un composant de substitution d'origine vegeetale stir pour traiter cette affection. La presente etude a eu pour objectif d'examiner l'effet de composes hydrosolubles d'abana (CHSA), une preparation a base de plantes meedicinales, traditionnellement utiliseee en Inde dans le traitement de l'hyperlipidemie, sur le metabolisme des cellules Hep[G.sub.2]. Les resultats font etat de l'effet des CHSA sur la reduction de la teneur en cholesterol et en triglycerides dans les cellules et leur surnageant. Les CHSA ont inhibe l'incorporation de [2-[sup.14]C]acetate dans le cholesterol et les acides gras cellulaires, donnant a penser a une inhibition de la synthase des lipides. Ils ont aussi inhibe la HMG-CoA reductase, une enzyme meetabolique cle impliquee dans la biosynthese du cholesterol. Ils ont de plus augmente la secretion du cholesterol et des acides gras dans le surnageant cellulaire, laissant croire a une elimination accrue du cholesterol et des acides gras. Enfin, ils ont montre une diminution de la teneur en acide linoleeique (18:2) et en acide arachidonique (20:4) dans les cellules Hep[G.sub.2]. Cette etude est la premiere du genre a montrer que les CHSA a la fois inhibent la biosynthese du cholesterol cellulaire et augmentent la secretion du cholesterol dans le surnageant cellulaire dans les cellules Hep[G.sub.2]. Mots-cles: Abana, cholesterol, triglyceride, acide gras, HMG-CoA, cholesterol, efflux. [Traduit par la Redaction], Introduction Plants have been used by humans for the treatment of various ailments since time immemorial, and screening of herbal drugs continues to offer opportunities for new drug discovery. The [...]

Mailhot G, Ravid Z, Barchi S, Moreau A, Rabasa-Lhoret R, Levy E. CFTR knockdown stimulates lipid synthesis and transport in intestinal Caco-2/15 cells. Am J Physiol Gastrointest Liver Physiol 297: G1239-G1249, 2009. First published October 1, 2009; doi: 10.1152/ajpgi.00206.2009.--Cystic fibrosis transmembrane conductance regulator (CFTR) is a chloride channel highly expressed in epithelial ceils of the gastrointestinal tract. Mutations in the CFTR gene cause cystic fibrosis (CF), a disease characterized by pancreatic insufficiency, fat malabsorption, and steatorrhea. Despite the administration of pancreatic enzymes to normalize malabsorption, CF patients still experienced lipid fecal loss, nutritional deficiencies, and abnormalities in serum lipid profile, suggesting the presence of intrinsic defects in the intestinal handling of nutrients. The objective of the present study was to assess the impact of CFTR gene knockdown on intracellular lipid metabolism of the intestinal Caco-2/15 cell line. Partial CFTR gene inactivation led to cellular lipid accretion of phospholipids, triglycerides, and cholesteryl esters. Likewise, secretion of these lipid fractions was significantly increased following CFTR gene manipulation. As expected from these findings, the output of triglyceride-rich lipoproteins showed the same increasing pattern. Investigation of the mechanisms underlying these changes revealed that CFTR knockdown resulted in raised levels of apolipoproteins in cells and media and microsomal transfer protein activity, two important factors for the efficient assembly and secretion of lipoproteins. Similarly, scrutiny of the enzymatic monoacylglycerol acyltransferase and diacylglycerol acyltransferase, which exhibit dynamic function in triacylglycerol resynthesis and chylomicron formation in enterocytes, revealed a significant augmentation in their activity. Conversely, cholesterol uptake mediated by Niemann-Pick C1 like 1, Scavenger Receptor Class B Type I, and ATP-binding cassette G8 remains unaffected by genetic modification of CFTR. Collectively, these results highlight the role played by CFTR in intestinal handling of lipids and may suggest that factors other than defective CFTR are responsible for the abnormal intracellular events leading to fat mal-absorption in CF patients. intestinal fat absorption; lipids; lipoproteins; apolipoproteins; cystic fibrosis doi: 10.1152/ajpgi.00206.2009

Cheng L, Hart X, Shi Y. A regulatory role of LPCAT1 in the synthesis of inflammatory lipids, PAF and LPC, in the retina of diabetic mice. Am J Physiol Endocrinol Metab 297: E1276-E1282, 2009. First published September 22, 2009; doi: 10.1152/ajpendo.00475.2009.--Platelet-activating factor (PAF) and lysophosphatidylcholine (LPC) are potent inflammatory lipids. Elevated levels of PAF and LPC are associated with the onset of diabetic retinopathy and neurodegeneration. However, the molecular mechanisms underlying such defects remain elusive. LPCAT1 is a newly reported lysophospholipid acyl-transferase implicated in the anti-inflammatory response by its role in conversion of LPC to PC. Intriguingly, the LPCATI enzyme also catalyzes the synthesis of PAF from lyso-PAF with use of acetyl-CoA as a substrate. The present studies investigated regulatory roles of LPCAT1 in the synthesis of inflammatory lipids during the onset of diabetes. Our work shows that LPCAT1 plays an important role in the inactivation of PAF by catalyzing the synthesis of alkyl-PC, an inactivated form of PAF with use of acyl-CoA and lyso-PAF as substrates. In support of a role of LPCAT1 in anti-inflammatory responses in diabetic retinopathy, LPCATI is most abundantly expressed in the retina. Moreover, LPCATI mRNA levels and acyltransferase activity toward lyso-PAF and LPC were significantly downregulated in retina and brain tissues in response to the onset of diabetes in lns[2.sup.Akita] and db/db mice, mouse models of type 1 and type 2 diabetes, respectively. Conversely, treatment of db/db mice with rosiglitazone, an antidiabetes compound, significantly upregulated LPCAT1 mRNA levels concurrently with increased acyltransferase activity in the retina and brain. Collectively, these findings identified a novel regulatory role of LPCAT1 in catalyzing the inactivation of inflammatory lipids in the retina of diabetic mice. lysophosphatidylcholine; lysophosphatidylcholine acyltransferase; diabetic retinopathy; platelet-activating factor doi: 10.1152/ajpendo.00475.2009

AcetyI-CoA produced in mitochondria from carbohydrate or amino acid catabolism needs to reach the cytosol to initiate de novo synthesis of fatty acids. All eukaryotes analyzed so far use a citrate/malate shuttle to transfer acetyl group equivalents from the mitochondrial matrix to the cytosol. Here we investigate how this acetyl group transfer occurs in the procyclic life cycle stage of Trypanosoma brucei, a protozoan parasite responsible of human sleeping sickness and economically important livestock diseases. Deletion of the potential citrate lyase gene, a critical cytosolic enzyme of the citrate/malate shuttle, has no effect on de novo biosynthesis of fatty acids from [sup.14]C-labeled glucose, indicating that another route is used for acetyl group transfer. Because acetate is produced from acetyI-CoA in the mitochondrion of this parasite, we considered genes encoding cytosolic enzymes producing acetyl-CoA from acetate. We identified an acetyI-CoA synthetase gene encoding a cytosolic enzyme (AceCS), which is essential for cell viability. Repression of AceCS by inducible RNAi results in a 20-fold reduction of [sup.14]C-incorporation from radiolabeled glucose or acetate into de novo synthesized fatty acids. Thus, we demonstrate that the essential cytosolic enzyme AceCS of T. brucei is responsible for activation of acetate into acetyl-CoA to feed de novo biosynthesis of lipids. To date, Trypanosoma is the only known eukaryotic organism that uses acetate instead of citrate to transfer acetyl groups over the mitochondrial membrane for cytosolic lipid synthesis. acetyl-CoA synthetase | citrate/malate shuttle | de novo lipid biosynthesis | mitochondrial acetate

Intestinal alkaline phosphatase (IAP) is a brush-border membrane ectoenzyme (BBM-IAP) that is released into the lumen (L-IAP) after a high-fat diet. We examined the effects of oil feeding and the addition of mixed-lipid micelles on the formation of L-IAP in oil-fed rat intestine, Caco-2 cell monolayers, and mouse intestinal loops. We localized IAP in the duodenum of rats fed corn oil using fluorescence microscopy with enzyme-labeled fluorescence-97 as substrate. Four hours after oil feeding, L-IAP increased ~10-fold accompanied by the loss of BBM-IAP, consistent with BBM-IAP release. Rat IAP isozyme mRNAs progressively increased 4-6 h after oil feeding, followed by the increase of IAP activity in the subapical location at 6 h, consistent with the restoration of IAP protein. Postprandial lipid-micelle components, sodium taurocholate with or without oleic acid, mono-oleylglycerol, cholesterol, or lysophosphatidylcholine (lysoPC) were applied singly or as mixed-lipid micelles to the apical surface of polarized Caco-2 cell monolayers. LysoPC increased L-IAP >10-fold over basal release. LysoPC released lAP into the apical medium more than other intestinal brush-border enzymes, 5'-nucleotidase, sucrase, aminopeptidase N, and lactase, without comparable lactate dehydrogenase release or cell injury. LysoPC increased human IAP mRNA levels by 1.5-fold in Caco-2 cells. Luminally applied lysoPC also increased release of IAP preferentially in mouse intestinal loops. These data show that lysoPC accelerates the formation of L-IAP from BBM-IAP, followed by enhanced IAP synthesis, suggesting the role that lysoPC might play in the turnover of brush-border proteins. Caco-2 cells; lipid absorption; small intestine; enzyme-labeled fluorescence-97

The storage of fatty acids and fatty alcohols in the form of neutral lipids such as triacylglycerol (TAG), cholesteryl ester (CE), and wax ester (WE) serves to provide reservoirs for membrane formation and maintenance, lipoprotein trafficking, lipid detoxification, evaporation barriers, and fuel in times of stress or nutrient deprivation. This ancient process likely originated in actinomycetes and has persisted in eukaryotes, albeit by different molecular mechanisms. A surfeit of neutral lipids is strongly, perhaps causally, related to several human diseases such as diabetes mellitus, obesity, atherosclerosis and nonalcoholic fatty liver disease. Therefore, understanding the metabolic pathways of neutral lipid synthesis and the roles of the enzymes involved may facilitate the development of new therapeutic interventions for these syndromes. acyltransferase; triacylglycerol; wax ester; wax diester; cholesteryl ester

A key and highly regulated enzyme that is required for the biosynthesis of monounsaturated fatty acids is stearoyl-CoA desaturase (SCD), which catalyzes the [D.sup.9]-cis desaturation of a range of fatty acyl-CoA substrates. The preferred substrates are palmitoyl- and stearoyl-CoA, which are converted into palmitoleoyl- and oleoyl-CoA respectively. Oleate is the most abundant monounsaturated fatty acid in dietary fat and is therefore readily available. Studies of mice that have a naturally occurring mutation in the SCD-1 gene isoform as well as a mouse model with a targeted disruption of the SCD gene (SCD-[1.sup.-/-]) have revealed the role of de novo synthesized oleate and thus the physiological importance of SCD-1 expression. SCD-1 deficiency results in reduced body adiposity, increased insulin sensitivity, and resistance to diet-induced obesity. The expression of several genes of lipid oxidation are upregulated, whereas lipid synthesis genes are downregulated. SCD-1 was also found to be a component of the novel metabolic response to the hormone leptin. Therefore, SCD-1 appears to be an important metabolic control point, and inhibition of its expression could be of benefit for the treatment of obesity, diabetes, and other metabolic diseases. In this article, we summarize the recent and timely advances concerning the important role of SCD in the biochemistry and physiology of lipid metabolism.

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.cell.2009.03.048 Byline: Robin Mathew (1)(5), Cristina M. Karp (3)(5), Brian Beaudoin (2)(3), Nhan Vuong (3), Guanghua Chen (2), Hsin-Yi Chen (3), Kevin Bray (3), Anupama Reddy (6), Gyan Bhanot (3)(5)(7), Celine Gelinas (1)(2), Robert S. DiPaola (4)(5), Vassiliki Karantza-Wadsworth (4)(5), Eileen White (1)(2)(3)(5) Keywords: CELLBIO; HUMDISEASE; SIGNALING Abstract: Allelic loss of the essential autophagy gene beclin1 occurs in human cancers and renders mice tumor-prone suggesting that autophagy is a tumor-suppression mechanism. While tumor cells utilize autophagy to survive metabolic stress, autophagy also mitigates the resulting cellular damage that may limit tumorigenesis. In response to stress, autophagy-defective tumor cells preferentially accumulated p62/SQSTM1 (p62), endoplasmic reticulum (ER) chaperones, damaged mitochondria, reactive oxygen species (ROS), and genome damage. Moreover, suppressing ROS or p62 accumulation prevented damage resulting from autophagy defects indicating that failure to regulate p62 caused oxidative stress. Importantly, sustained p62 expression resulting from autophagy defects was sufficient to alter NF-[kappa]B regulation and gene expression and to promote tumorigenesis. Thus, defective autophagy is a mechanism for p62 upregulation commonly observed in human tumors that contributes directly to tumorigenesis likely by perturbing the signal transduction adaptor function of p62-controlling pathways critical for oncogenesis. Author Affiliation: (1) University of Medicine and Dentistry of New Jersey, Robert Wood Johnson Medical School, Piscataway, NJ 08854, USA (2) Center for Advanced Biotechnology and Medicine, Rutgers University, 679 Hoes Lane, Piscataway, NJ 08854, USA (3) Department of Molecular Biology and Biochemistry, Rutgers University, 604 Allison Road, Piscataway, NJ 08854, USA (4) Division of Medical Oncology, University of Medicine and Dentistry of New Jersey, Robert Wood Johnson Medical School, 675 Hoes Lane, Piscataway, NJ 08854, USA (5) The Cancer Institute of New Jersey, 195 Little Albany Street, New Brunswick, NJ 08903, USA (6) RUTCOR, Rutgers University, Piscataway, NJ 08854, USA (7) Department of Physics, Rutgers University, Piscataway, NJ 08854, USA Article History: Received 16 August 2008; Revised 23 December 2008; Accepted 23 March 2009 Article Note: (miscellaneous) Published: June 11, 2009

We investigated the mechanisms whereby peroxisome proliferator-activated receptor-[gamma], (PPAR[gamma]) agonism affects glucose and lipid metabolism in brown adipose tissue (BAT) by studying the impact of PPAR[gamma] activation on BAT glucose uptake and metabolism, lipogenesis, and mRNA levels plus activities of enzymes involved in triacylglycerol (TAG) synthesis. Interscapular BAT of rats treated or not with rosiglitazone (15 mg x [kg.sup.-1] x [day.sup.-1], 7 days) was evaluated in vivo for glucose uptake and lipogenesis and in vitro for glucose metabolism, gene expression, and activities of glycerolphosphate acyltransferase (GPAT), phosphatidate phosphatase-1 (PAP or lipin-1), and diacylglycerol acyltransferase (DGAT). Rosiglitazone increased BAT mass without affecting whole tissue glucose uptake. BAT glycogen content (-80%), its synthesis from glucose (-50%), and mRNA levels of UDP-glucose pyrophosphorylase (-40%), which generates UDP-linked glucose for glycogen synthesis, were all reduced by rosiglita-zone. In contrast, BAT TAG-glycerol synthesis in vivo and glucose incorporation into TAG-glycerol in vitro were stimulated by the agonist along with the activities and mRNA levels of glycerol 3-phosphate-generating phosphoenolpyruvate carboxykinase and glycerokinase. Furthermore, rosiglitazone markedly increased the activities of GPAT and DGAT but not those of lipin-l-mediated PAP-l, enzymes involved in the sequential acylation of glycerol 3-phosphate and TAG synthesis. Because an adequate supply of fatty acids is essential for BAT nonshivering thermogenesis, the enhanced ability of BAT to synthesize TAG under PPAR[gamma] activation may constitute an important mechanism by which lipid substrates are stored in preparation for an eventual thermogenic activation. glycogen; glycerokinase; phosphoenolpyruvate carboxykinase; glycerolphosphate acyltransferase; lipin; diacylglycerol acyltransferase; peroxisome proliferator-activated receptor-[gamma]

Our aim was to study the effects of increased dietary intake of [alpha]-Iinolenic acid (ALA), eicosapentaenoic acid (EPA), or docosahexaenoic acid (DHA) on serum lipids and LDL fatty acid compositions. To this end, a controlled parallel study was conducted in 74 healthy normolipidemic men and women aged 19-43 y. Participants were randomly assigned to 1 of 3 interventions and consumed a total intake of 4.4 g/d ALA (ALA group), 2.2 g/d EPA (EPA group), and 2.3 g/d DHA (DHA group) for 6 wk. Fatty acid ethyl esters were incorporated into margarines, which replaced the participant's normal spread. The ALA, EPA, or DHA intake led to a significant enrichment of the LDL with the respective (n-3) fatty acid. In addition, LDL EPA contents in the ALA group increased by 36% (P< 0.05) with no changes in LDL DHA. The EPA intervention led to an additional enrichment with DHA (24%; P< 0.001), whereas the DHA intervention further increased the amount of EPA (249%; P< 0.001). ALA, EPA, or DHA intake did not affect fasting serum concentrations of total and LDL cholesterol, but fasting serum triacylglycerol concentrations significantly decreased in the EPA (-0.14 mmol/L) and DHA (-0.30 mmol/L) interventions and also in the ALA intervention (-0.17 mmol/L). DHA intake significantly increased serum HDL cholesterol, whereas no changes were found with ALA or EPA intake. In conclusion, the present data support the hypothesis that isolated dietary ALA, EPA, and DHA intakes lead to differential enrichment in LDL due to interconversion. Moderate amounts of ALA, EPA, and DHA are effective in improving lipid profiles of normolipidemic humans.