Deregulated lipid sensing by intestinal CD36 in diet-induced hyperinsulinemic obese mouse model

The metabolic syndrome (MetS) greatly increases risk of cardiovascular disease and diabetes and is generally associated with abnormally elevated postprandial triglyceride levels. We evaluated intestinal synthesis of triglyceride-rich lipoproteins (TRL) in a mouse model of the MetS obtained by feeding a palm oil-rich high fat diet (HFD). By contrast to control mice, MetS mice secreted two populations of TRL. If the smaller size population represented 44% of total particles in the beginning of intestinal lipid absorption in MetS mice, it accounted for only 17% after 4 h due to the secretion of larger size TRL. The MetS mice displayed accentuated postprandial hypertriglyceridemia up to 3 h due to a defective TRL clearance. These alterations reflected a delay in lipid induction of genes for key proteins of TRL formation (MTP, L-FABP) and blood clearance (ApoC2). These abnormalities associated with blunted lipid sensing by CD36, which is normally required to optimize jejunal formation of large TRL. In MetS mice CD36 was not downregulated by lipid in contrast to control mice. Treatment of controls with the proteosomal inhibitor MG132, which prevented CD36 downregulation, resulted in blunted lipid-induction of MTP, L-FABP and ApoC2 gene expression, as in MetS mice. Absence of CD36 sensing was due to the hyperinsulinemia in MetS mice. Acute insulin treatment of controls before lipid administration abolished CD36 downregulation, lipid-induction of TRL genes and reduced postprandial triglycerides (TG), while streptozotocin-treatment of MetS mice restored lipid-induced CD36 degradation and TG secretion. In vitro, insulin treatment abolished CD36-mediated up-regulation of MTP in Caco-2 cells. In conclusion, HFD treatment impairs TRL formation in early stage of lipid absorption via insulin-mediated inhibition of CD36 lipid sensing. This impairment results in production of smaller TRL that are cleared slowly from the circulation, which might contribute to the reported association of CD36 variants with MetS risk

Full field modeling of recrystallization and grain growth thanks to a level set approach: towards modeling by industry

International audienceMetal forming modeling can be predictive only if the strain rate, strain and temperature dependency of the flow behaviour are correctly described. The mechanical properties and behaviour of metallic materials mainly depends on the content and structure of dislocation network, this points out the need to incorporate microstructure concepts into the numerical models. The goal is to correctly describe the main physical mechanisms occurring in metals during thermomechanical processes i.e. work-hardening, recovery, grain boundary migration, nucleation and grain growth related to dynamic, static or metadynamic recrystallization. Macroscopic and homogenized models are widely used in the industry, mainly due to their low computational cost. If this mean field framework is quite convenient, it can be synonymous, for a given material, with a large amount of experiments with advanced laboratory devices. Moreover, the homogenization of the microstructure does not permit to capture some very local phenomena

Link between Intestinal CD36 Ligand Binding and Satiety Induced by a High Protein Diet in Mice

CD36 is a ubiquitous membrane glycoprotein that binds long-chain fatty acids. The presence of a functional CD36 is required for the induction of satiety by a lipid load and its role as a lipid receptor driving cellular signal has recently been demonstrated. Our project aimed to further explore the role of intestinal CD36 in the regulation of food intake. Duodenal infusions of vehicle or sulfo-N-succinimidyl-oleate (SSO) was performed prior to acute infusions of saline or Intralipid (IL) in mice. Infusion of minute quantities of IL induced a decrease in food intake (FI) compared to saline. Infusion of SSO had the same effect but no additive inhibitory effect was observed in presence of IL. No IL- or SSO-mediated satiety occurred in CD36-null mice. To determine whether the CD36-mediated hypophagic effect of lipids was maintained in animals fed a satietogen diet, mice were subjected to a High-Protein diet (HPD). Concomitantly with the satiety effect, a rise in intestinal CD36 gene expression was observed. No satiety effect occurred in CD36-null mice. HPD-fed WT mice showed a diminished FI compared to control mice, after saline duodenal infusion. But there was no further decrease after lipid infusion. The lipid-induced decrease in FI observed on control mice was accompanied by a rise in jejunal oleylethanolamide (OEA). Its level was higher in HPD-fed mice than in controls after saline infusion and was not changed by lipids. Overall, we demonstrate that lipid binding to intestinal CD36 is sufficient to produce a satiety effect. Moreover, it could participate in the satiety effect induced by HPD. Intestine can modulate FI by several mechanisms including an increase in OEA production and CD36 gene expression. Furthermore, intestine of mice adapted to HPD have a diminished capacity to modulate their food intake in response to dietary lipids

Viral to metazoan marine plankton nucleotide sequences from the Tara Oceans expedition

A unique collection of oceanic samples was gathered by the Tara Oceans expeditions (2009-2013), targeting plankton organisms ranging from viruses to metazoans, and providing rich environmental context measurements. Thanks to recent advances in the field of genomics, extensive sequencing has been performed for a deep genomic analysis of this huge collection of samples. A strategy based on different approaches, such as metabarcoding, metagenomics, single-cell genomics and metatranscriptomics, has been chosen for analysis of size-fractionated plankton communities. Here, we provide detailed procedures applied for genomic data generation, from nucleic acids extraction to sequence production, and we describe registries of genomics datasets available at the European Nucleotide Archive (ENA, www.ebi.ac.uk/ena). The association of these metadata to the experimental procedures applied for their generation will help the scientific community to access these data and facilitate their analysis. This paper complements other efforts to provide a full description of experiments and open science resources generated from the Tara Oceans project, further extending their value for the study of the world's planktonic ecosystems

Improvement of conducting polymer gas sensors

The use of gas sensors is rapidly increasing, along with the number of candidate materials for gas sensing applications. In order to improve their competitivity, conducting polymer gas sensors have to be constantly improved. This work on conducting polymer chemoresistive gas sensors consists in improving the quality regarding three aspects: the substrates, the sensitive layer itself and the sensing mechanism of these devices.A new array of micromachined devices was developed, comprising a new design (array of 4 discreet devices) and a new electrode material (platinum). This array was found to be more suitable for the requirements of our electronic nose applications. The electrochemistry of the electrode material was also employed to check the quality and to condition the substrates prior to every single electropolymerisation, which was reflected by an increase in quality.Poly(pyrrole) and poly(aniline) doped with alkyl sulfonate were investigated as well as new coatings doped with aromatic sulfonate or metal phthalocyanine sulfonate. Their sensitivity towards CO and NO2 was evaluated for possible applications in the automotive industry. The reproducibility from sensor to sensor was also addressed. Monitoring in-situ the resistance of the film during the electrodeposition, employing a technique specially designed for this purpose led to significant improvement in the reproducibility but also in the response time and in the stability over time.The conducting polymers gas sensors were also tested towards ethanol and water, both as coatings for chemoresistive devices and QCM sensors. The aim was to get a deeper insight into the sensing mechanism of these gas sensitive materials in order to be able to engineer a coating for a given vapour. Following conductivity, viscoelasticity and mass upon exposure demonstrated that a Langmuir adsorption isotherm model was not suitable. A new model was defined, a double-diffusion model, where the vapour diffuses rapidly in the pores of the polymer before penetrating in the material itself, explaining the large response time of the conducting polymer gas sensors.</p

Le gène de l'I-BABP (implication dans l'homéostasie du cholestérol ?)

DIJON-BU Sciences Economie (212312102) / SudocSudocFranceF

Monsieur Homais, un pharmacien au XIXe siècle

CAEN-BU Médecine pharmacie (141182102) / SudocCAEN-BU Droit Lettres (141182101) / SudocLYON1-BU Santé (693882101) / SudocSudocFranceF

Appetite control by the tongue-gut axis and evaluation of the role of CD36/SR-B2.

IF 3.112International audienceUnderstanding the mechanisms governing food intake is a public health issue given the dramatic rise of obesity over the world. The overconsumption of tasty energy-dense foods rich in lipids is considered to be one of the nutritional causes of this epidemic. Over the last decade, the identification of fatty acid receptors in strategic places in the body (i.e. oro-intestinal tract and brain) has provided a major progress in the deciphering of regulatory networks involved in the control of dietary intake. Among these lipid sensors, CD36/SR-B2 appears to play a significant role since this membrane protein, known to bind long-chain fatty acid with a high affinity, was specifically found both in enterocytes and in a subset of taste bud cells and entero-endocrine cells. After a short overview on CD36/SR-B2 structure, function and regulation, this mini-review proposes to analyze the key findings about the role of CD36/SR-B2 along of the tongue-gut axis in relation to appetite control. In addition, we discuss whether obesogenic diets might impair lipid sensing mediated by CD36/SR-B2 along this axis

Les acides linoléiques conjugués (CLA) permettent-ils de lutter contre l’obésité sans risque ?

International audienceAmong the conjugated linoleic acid (CLA) isomer 10t,12c-CLA is nutritionally and commercially attractive since it has anti-obesity effects. However, this fatty acid triggers in mice a drastic decrease in adipose tissue mass, which is associated with side effects such as insulin resistance, hepatic steatosis and cholelithiasis risk. The aim of this review is to understand mechanisms responsible for these effects observed in mice and consider their existence in humans.Parmi les acides linoléiques conjugués (CLA), l’isomère 10t,12c-CLA est nutritionnellement et commercialement attrayant puisqu’il a un effet anti-obésité. Cependant, cet acide gras en parallèle d’une fonte drastique du tissu adipeux, déclenche chez la souris des effets indésirables comme une insulinorésistance, une stéatose hépatique et une augmentation des risques de cholélithiase biliaire. L’objectif de cette revue est de comprendre les mécanismes à l’origine de ces effets à partir des données obtenues chez la souris et de vérifier leur existence chez l’Homme