Cholesterol and Fatty Acids Regulate Dynamic Caveolin Trafficking through the Golgi Complex and between the Cell Surface and Lipid Bodies

Caveolins are a crucial component of plasma membrane (PM) caveolae but have also been localized to intracellular compartments, including the Golgi complex and lipid bodies. Mutant caveolins associated with human disease show aberrant trafficking to the PM and Golgi accumulation. We now show that the Golgi pool of mainly newly synthesized protein is detergent-soluble and predominantly in a monomeric state, in contrast to the surface pool. Caveolin at the PM is not recognized by specific caveolin antibodies unless PM cholesterol is depleted. Exit from the Golgi complex of wild-type caveolin-1 or -3, but not vesicular stomatitis virus-G protein, is modulated by changing cellular cholesterol levels. In contrast, a muscular dystrophy-associated mutant of caveolin-3, Cav3P104L, showed increased accumulation in the Golgi complex upon cholesterol treatment. In addition, we demonstrate that in response to fatty acid treatment caveolin can follow a previously undescribed pathway from the PM to lipid bodies and can move from lipid bodies to the PM in response to removal of fatty acids. The results suggest that cholesterol is a rate-limiting component for caveolin trafficking. Changes in caveolin flux through the exocytic pathway can therefore be an indicator of cellular cholesterol and fatty acid levels.

Induction of the acyl-coenzyme A synthetase gene by fibrates and fatty acids is mediated by a peroxisome proliferator response element in the C promoter.

The long-chain acyl-coenzyme A synthetase (ACS) gene gives rise to three transcripts containing different first exons preceded by specific regulatory regions A, B, and C. Exon-specific oligonucleotide hybridization indicated that only A-ACS mRNA is expressed in rat liver. Fibrate administration induced liver C-ACS strongly and A-ACS mRNA to a lesser extent. B-ACS mRNA remained undetectable. In primary rat hepatocytes and Fa-32 hepatoma cells C-ACS mRNA increased after treatment with fenofibric acid, alpha-bromopalmitate, tetradecylthioacetic acid, or alpha-linolenic acid. Nuclear run-on experiments indicated that fenofibric acid and alpha-bromopalmitate act at the transcriptional level. Transient transfections showed a 3.4-, 2.3-, and 2.2-fold induction of C-ACS promoter activity after fenofibric acid, alpha-bromopalmitate, and tetradecylthioacetic acid, respectively. Unilateral deletion and site-directed mutagenesis identified a peroxisome proliferator activator receptor (PPAR)-responsive element (PPRE) mediating the responsiveness to fibrates and fatty acids. This ACS PPRE contains three imperfect half sites spaced by 1 and 3 oligonucleotides and binds PPAR.retinoid X receptor heterodimers in gel retardation assays. In conclusion, the regulation of C-ACS mRNA expression by fibrates and fatty acids is mediated by PPAR.retinoid X receptor heterodimers interacting through a PPRE in the C-ACS promoters. PPAR therefore occupies a key position in the transcriptional control of a pivotal enzyme controlling the channeling of fatty acids into various metabolic pathways.

Analysis of the alternative pathways for the beta-oxidation of unsaturated fatty acids using transgenic plants synthesizing polyhydroxyalkanoates in peroxisomes.

Degradation of fatty acids having cis-double bonds on even-numbered carbons requires the presence of auxiliary enzymes in addition to the enzymes of the core beta-oxidation cycle. Two alternative pathways have been described to degrade these fatty acids. One pathway involves the participation of the enzymes 2, 4-dienoyl-coenzyme A (CoA) reductase and Delta(3)-Delta(2)-enoyl-CoA isomerase, whereas the second involves the epimerization of R-3-hydroxyacyl-CoA via a 3-hydroxyacyl-CoA epimerase or the action of two stereo-specific enoyl-CoA hydratases. Although degradation of these fatty acids in bacteria and mammalian peroxisomes was shown to involve mainly the reductase-isomerase pathway, previous analysis of the relative activity of the enoyl-CoA hydratase II (also called R-3-hydroxyacyl-CoA hydro-lyase) and 2,4-dienoyl-CoA reductase in plants indicated that degradation occurred mainly through the epimerase pathway. We have examined the implication of both pathways in transgenic Arabidopsis expressing the polyhydroxyalkanoate synthase from Pseudomonas aeruginosa in peroxisomes and producing polyhydroxyalkanoate from the 3-hydroxyacyl-CoA intermediates of the beta-oxidation cycle. Analysis of the polyhydroxyalkanoate synthesized in plants grown in media containing cis-10-heptadecenoic or cis-10-pentadecenoic acids revealed a significant contribution of both the reductase-isomerase and epimerase pathways to the degradation of these fatty acids.

Cholesterol and fatty acids regulate dynamic caveolin trafficking through the golgi complex and between the cell surface and lipid bodies

Caveolins are a crucial component of plasma membrane (PM) caveolae but have also been localized to intracellular compartments, including the Golgi complex and lipid bodies. Mutant caveolins associated with human disease show aberrant trafficking to the PM and Golgi accumulation. We now show that the Golgi pool of mainly newly synthesized protein is detergent-soluble and predominantly in a monomeric state, in contrast to the surface pool. Caveolin at the PM is not recognized by specific caveolin antibodies unless PM cholesterol is depleted. Exit from the Golgi complex of wild-type caveolin-1 or -3, but not vesicular stomatitis virus-G protein, is modulated by changing cellular cholesterol levels. In contrast, a muscular dystrophy-associated mutant of caveolin-3, Cav3P104L, showed increased accumulation in the Golgi complex upon cholesterol treatment. In addition, we demonstrate that in response to fatty acid treatment caveolin can follow a previously undescribed pathway from the PM to lipid bodies and can move from lipid bodies to the PM in response to removal of fatty acids. The results suggest that cholesterol is a rate-limiting component for caveolin trafficking. Changes in caveolin flux through the exocytic pathway can therefore be an indicator of cellular cholesterol and fatty acid levels.

Fatty acid composition, antioxidants and lipid oxidation in chicken breasts from different production regimes

Chicken breast from nine products and from the following production regimes: conventional (chilled and frozen), organic and free range, were analysed for fatty acid composition of total lipids, preventative and chain breaking antioxidant contents and lipid oxidation during 5 days of sub-ambient storage following purchase. Total lipids were extracted with an optimal amount of a cold chloroform methanol solvent. Lipid compositions varied, but there were differences between conventional and organic products in their contents of total polyunsaturated fatty acids and n-3 and n-6 fatty acids and n-6:n-3 ratio. Of the antioxidants, a-tocopherol content was inversely correlated with lipid oxidation. The antioxidant enzyme activities of catalase, glutathione peroxidase and glutathione reductase varied between products. Modelling with partial least squares regression showed no overall relationship between total antioxidants and lipid data, but certain individual antioxidants showed a relationship with specific lipid fractions.

Effect of fatty acids on hyphal growth in the pathogenic yeast Candida albicans

Candida albicans est une levure pathogène qui, à l’état commensal, colonise les muqueuses de la cavité orale et du tractus gastro-intestinal. De nature opportuniste, C. albicans cause de nombreuses infections, allant des candidoses superficielles (muguet buccal, vulvo-vaginite) aux candidoses systémiques sévères. C. albicans a la capacité de se développer sous diverses morphologies, telles que les formes levures, pseudohyphes et hyphes. Des stimuli environnementaux mimant les conditions retrouvées chez l’hôte (température de 37°C, pH neutre, présence de sérum) induisent la transition levure-à-hyphe (i.e. morphogenèse ou filamentation). Cette transition morphologique contribue à la pathogénicité de C. albicans, du fait que des souches présentant un défaut de filamentation sont avirulentes. Non seulement la morphogenèse est un facteur de virulence, mais elle constituerait aussi une cible pour le développement d’antifongiques. En effet, il a déjà été démontré que l’inhibition de la transition levure-à-hyphe atténuait la virulence de C. albicans lors d’infections systémiques. Par ailleurs, des études ont démontré que de nombreuses molécules pouvaient moduler la morphogenèse. Parmi ces molécules, certains acides gras, dont l’acide linoléique conjugué (CLA), inhibent la formation d’hyphes. Ainsi, le CLA posséderait des propriétés thérapeutiques, du fait qu’il interfère avec un déterminant de pathogénicité de C. albicans. Par contre, avant d’évaluer son potentiel thérapeutique dans un contexte clinique, il est essentiel d’étudier son mode d’action. Ce projet vise à caractériser l’activité anti-filamentation des acides gras et du CLA et à déterminer le mécanisme par lequel ces molécules inhibent la morphogenèse chez C. albicans. Des analyses transcriptomiques globales ont été effectuées afin d’obtenir le profil transcriptionnel de la réponse de C. albicans au CLA. L’acide gras a entraîné une baisse des niveaux d’expression de gènes encodant des protéines hyphes-spécifiques et des régulateurs de morphogenèse, dont RAS1. Ce gène code pour la GTPase Ras1p, une protéine membranaire de signalisation qui joue un rôle important dans la transition levure-à-hyphe. Des analyses de PCR quantitatif ont confirmé que le CLA inhibait l’induction de RAS1. De plus, le CLA a non seulement causé une baisse des niveaux cellulaires de Ras1p, mais a aussi entraîné sa délocalisation de la membrane plasmique. En affectant les niveaux et la localisation cellulaire de Ras1p, le CLA nuit à l’activation de la voie de signalisation Ras1p-dépendante, inhibant ainsi la morphogenèse. Il est possible que le CLA altère la structure de la membrane plasmique et affecte indirectement la localisation membranaire de Ras1p. Ces travaux ont permis de mettre en évidence le mode d’action du CLA. Le potentiel thérapeutique du CLA pourrait maintenant être évalué dans un contexte d’infection, permettant ainsi de vérifier qu’une telle approche constitue véritablement une stratégie pour le traitement des candidoses.

Chronic disease risk associated with different dietary saturated fatty acids

This chapter compares the risks of chronic disease, and cardiovascular disease in particular, associated with consumption of different saturated fatty acids. Emphasis is placed on the effects of stearic acid as this has potential to replace trans fatty acids in certain manufactured food products. The chapter first reviews the effects of individual saturated fatty acids on blood lipids, including cholesterol, as these are commonly used as markers of disease risk. It then looks directly at evidence in relation to health outcomes. Finally, recent evidence specifically on the effect of stearic acid relative to other fatty acids, including trans fatty acids, is summarised.

Exploring the association of diary product intake with the fatty acids C15:0 and C17:0 measured from dried blood spots in a multi-population cohort: findings from the Food4Me study

Scope: The use of biomarkers in the objective assessment of dietary intake is a high priority in nutrition research. The aim of this study was to examine pentadecanoic acid (C15:0) and heptadecanoic acid (C17:0) as biomarkers of dairy foods intake. Methods and results: The data used in the present study were obtained as part of the Food4me Study. Estimates of C15:0 and C17:0 from dried blood spots and intakes of dairy from an FFQ were obtained from participants (n=1,180) across 7 countries. Regression analyses were used to explore associations of biomarkers with dairy intake levels and receiver operating characteristic (ROC) analyses were used to evaluate the fatty acids. Significant positive associations were found between C15:0 and total intakes of high-fat dairy products. C15:0 showed good ability to distinguish between low and high consumers of high-fat dairy products. Conclusion: C15:0 can be used as a biomarker of high-fat dairy intake and of specific high-fat dairy products. Both C15:0 and C17:0 performed poorly for total dairy intake highlighting the need for caution when using these in epidemiological studies.

Mechanisms underlying skeletal muscle insulin resistance induced by fatty acids: importance of the mitochondrial function

Insulin resistance condition is associated to the development of several syndromes, such as obesity, type 2 diabetes mellitus and metabolic syndrome. Although the factors linking insulin resistance to these syndromes are not precisely defined yet, evidence suggests that the elevated plasma free fatty acid (FFA) level plays an important role in the development of skeletal muscle insulin resistance. Accordantly, in vivo and in vitro exposure of skeletal muscle and myocytes to physiological concentrations of saturated fatty acids is associated with insulin resistance condition. Several mechanisms have been postulated to account for fatty acids-induced muscle insulin resistance, including Randle cycle, oxidative stress, inflammation and mitochondrial dysfunction. Here we reviewed experimental evidence supporting the involvement of each of these propositions in the development of skeletal muscle insulin resistance induced by saturated fatty acids and propose an integrative model placing mitochondrial dysfunction as an important and common factor to the other mechanisms.

A component of the mitochondrial outer membrane proteome of T. brucei probably contains covalent bound fatty acids

A subclass of eukaryotic proteins is subject to modification with fatty acids, the most common of which are palmitic and myristic acid. Protein acylation allows association with cellular membranes in the absence of transmembrane domains. Here we examine POMP39, a protein previously described to be present in the outer mitochondrial membrane proteome (POMP) of the protozoan parasite Trypanosoma brucei. POMP39 lacks canonical transmembrane domains, but is likely both myristoylated and palmitoylated on its N-terminus. Interestingly, the protein is also dually localized on the surface of the mitochondrion as well as in the flagellum of both insect-stage and the bloodstream form of the parasites. Upon abolishing of global protein acylation or mutation of the myristoylation site, POMP39 relocates to the cytosol. RNAi-mediated ablation of the protein neither causes a growth phenotype in insect-stage nor bloodstream form trypanosomes.

Acyl tunichlorins: a new class of nickel chlorins isolated from the Caribbean tunicate Trididemnum solidum.

A new class of nickel-containing chlorins (acyl tunichlorins) has been isolated from the Caribbean tunicate Trididemnum solidum. The structures of 28 of these nickel (II) hydroporphyrins were elucidated using mass spectrometry, one- and two-dimensional NMR spectroscopy, and chemical degradation/derivatization. Unique structural features of these compounds include the diversity of aliphatic side chains, which are derived from C14:0 to C22:6 fatty acids, and their location at an unprecedented position at C-2a on the hydroporphyrin nucleus. No chlorins with ester-linked acyl side chains at C-2a have been reported previously. Although the exact biological role that these compounds play in T. solidum remains unknown, acyl tunichlorins represent the only nickel-containing chlorins to be isolated from a living system and are the C-2a acyl derivatives of tunichlorin, a nickel chlorin reported by this laboratory in 1988.

Evaluation of chronic omega-3 fatty acids supplementation on behavioral and neurochemical alterations in 6-hydroxydopamine-lesion model of Parkinson`s disease

Omega-3 polyunsaturated fatty acids (omega-3 PUFAs) have been widely associated to beneficial effects over different neuropathologies, but only a few studies associate them to Parkinson`s disease (PD). Rats were submitted to chronic supplementation (21-90 days of life) with fish oil, rich in omega-3 PUFAs, and were uni- or bilaterally lesioned with 4 mu g of the neurotoxin 6-hydroxydopamine (6-OHDA) in the medial forebrain bundle Although lipid incorporation was evidenced in neuronal membranes, it was not sufficient to compensate motor deficits induced by 6-OHDA. In contrast, omega-3 PUFAs were capable of reducing rotational behavior induced by apomorphine, suggesting neuroprotection over dyskinesia The beneficial effects of omega-3 PUFAs were also evident in the maintenance of thiobarbituric acid reactive substances index from animals lesioned with 6-OHDA similar to levels from SHAM and intact animals. Although omega-3 PUFAs did not modify the tyrosine hydroxylase immunoreactivity in the substantia nigra pars compacta and in the ventral tegmental area, nor the depletion of dopamine (DA) and its metabolites in the striatum, DA turnover was increased after omega-3 PUFAs chronic supplementation Therefore, it is proposed that omega-3 PUFAs action characterizes the adaptation of remaining neurons activity. altering striatal DA turnover without modifying the estimated neuronal population. (C) 2009 Elsevier Ireland Ltd and the Japan Neuroscience Society. All rights reserved

Omega 3 fatty acids induce a marked reduction of apolipoprotein B48 when added to fluvastatin in patients with type 2 diabetes and mixed hyperlipidemia: a preliminary report

BACKGROUND Mixed hyperlipidemia is common in patients with diabetes. Statins, the choice drugs, are effective at reducing lipoproteins that contain apolipoprotein B100, but they fail to exert good control over intestinal lipoproteins, which have an atherogenic potential. We describe the effect of prescription omega 3 fatty acids on the intestinal lipoproteins in patients with type 2 diabetes who were already receiving fluvastatin 80 mg per day. METHODS Patients with type 2 diabetes and mixed hyperlipidemia were recruited. Fasting lipid profile was taken when patients were treated with diet, diet plus 80 mg of fluvastatin and diet plus fluvastatin 80 mg and 4 g of prescription omega 3 fatty acids. The intestinal lipoproteins were quantified by the fasting concentration of apolipoprotein B48 using a commercial ELISA. RESULTS The addition of 4 g of prescription omega 3 was followed by significant reductions in the levels of triglycerides, VLDL triglycerides and the triglyceride/HDL cholesterol ratio, and an increase in HDL cholesterol (P < 0.05). Fluvastatin induced a reduction of 26% in B100 (P < 0.05) and 14% in B48 (NS). However, the addition of omega 3 fatty acids enhanced this reduction to 32% in B100 (NS) and up to 36% in B48 (P < 0.05). CONCLUSION Our preliminary findings therefore suggest an additional benefit on postprandial atherogenic particles when omega 3 fatty acids are added to standard treatment with fluvastatin.

Omega-3 poly-unsaturated fatty acids for the prevention of severe neutropenic enterocolitis in patients with acute myeloid leukemia

Neutropenic enterocolitis is a potentially fatal complication of myeloablative chemotherapy in patients with acute myeloid leukemia. Omega-3 polyunsaturated fatty acids (PUFA) are precursors of potent anti-inflammatory prostaglandins. Our aim was to explore the safety and effectiveness of omega-3 PUFA added to parenteral nutrition in protecting leukemia patients from severe enterocolitis. Fourteen patients with acute myeloid leukemia who received omega-3 PUFA in a Phase II trial were compared with 66 consecutive control patients not getting this intervention. We performed crude and adjusted comparisons, using inverse probability of treatment weighting for adjusted analysis, and blind outcome assessment to minimize assessor bias. Primary outcome was severe enterocolitis (≥Grade 3). The crude odds ratio of Grade 3 colitis or higher was 1.36 (95% CI 0.37 to 4.96, P = 0.64), and the adjusted odds ratio was 0.79 (95% CI 0.35 to 1.78, P = 0.57). There was little evidence to suggest differences between groups in serious adverse events and overall mortality. Our results provide little evidence that addition of omega-3 PUFA is beneficial in this condition. Routine treatment with omega-3 PUFA is currently not warranted.

Omega-3 Fatty Acids are Related to Abnormal Emotion Processing in Adolescent Boys with Attention Deficit Hyperactivity Disorder

Background In addition to the core symptoms, attention deficit hyperactivity disorder (ADHD) is associated with poor emotion regulation. There is some evidence that children and young adults with ADHD have lower omega-3 levels and that supplementation with omega-3 can improve both ADHD and affective symptoms. We therefore investigated differences between ADHD and non-ADHD children in omega-3/6 fatty acid plasma levels and the relationship between those indices and emotion-elicited event-related potentials (ERPs). Methods Children/adolescents with (n=31) and without ADHD (n=32) were compared in their plasma omega-3/6 indices and corresponding ERPs during an emotion processing task. Results Children with ADHD had lower mean omega-3/6 and ERP abnormalities in emotion processing, independent of emotional valence relative to control children. ERP abnormalities were significantly associated with lower omega-3 levels in the ADHD group. Conclusions The findings reveal for the first time that lower omega-3 fatty acids are associated with impaired emotion processing in ADHD children.