Rôle du récepteur nucléaire Farnesoid X (receptor (FXR) dans la différenciation et la fonction adipocytaire)

Les acides biliaires (ABs) ne sont pas seulement des simples détergents pour les lipides mais aussi des molécules affectant différents fonctions endocrines. Leurs actions régulatrice est médiée par le facteur de transcription Farnesoid X Receptor (FXR), ces ABs sont considérés comme les ligands endogènes de FXR. En plus d'être un régulateur clé de l'acide biliaire, le métabolisme des lipides et du glucose, le récepteur nucléaire FXR a récemment était impliqué dans le contrôle de la différenciation adipocytaire in vitro et in vivo. Le degré de sa contribution et les mécanismes moléculaires impliqués demeurent inconnus. Le but de notre étude est d élucider le rôle de FXR dans la fonction adipocytaire et dans la régulation de la voie d activation de PPARg. Pour cela, nous avons étudiés la réponse des souris FXR-/- à l activation de PPARg par la rosiglitazone. Nos résultats montrent que les souris FXR-/- obèses présentent une résistance au traitement rosiglitazone. In vitro, le traitement rosiglitazone n induit pas une différenciation adipocytaire normale et la formation des gouttelettes lipidiques dans les MEFs FXR-/-. De plus, les MEFs FXR-/- montrent une augmentation de la lipolyse et une diminution de la lipgenèse de novo, ce qui en résulte une diminution du contenu en triglycérides intracellulaires. La réintroduction de FXR dans les MEFs FXR-/- améliore la différenciation adipocytaire. l expression des gènes de la voie Wnt/b-caténine ainsi que leurs gènes cibles augmentent dans le tissu adipeux des souris FXR- /- et dans les MEFs. En revanche l expression de différents inhibiteurs de la voie Wnt/b- caténine diminue à un stade précoce dans les MEFs FXR-/-. En conclusion, notre étude montre que FXR régule la fonction et la différenciation adipocytaire en régulant deux voies opposées, la voie PPARg et la voie Wnt/b-caténine.LILLE2-BU Santé-Recherche (593502101) / SudocSudocFranceF

PRDM16 Gene Polymorphism Is Associated with Obesity and Blood Lipids Profiles in Saudi Population

Aims: The PR domain containing 16 (PRDM16) gene and the Phosphodiesterase 4D (PDE4) gene are both an essential regulators in the thermogenesis process in the brown adipose tissues (BAT). The influence of polymorphisms in those genes on obesity and blood lipids profile is unknown particularly in the Saudi population, so the current study is aiming to explore that. Methods: A case control format was used that involved 89 obese individual and 84 non-obese (control). The PRDM16 (rs2651899) and PDE4D (rs295978) polymorphisms were genotyped using KASP™ (Competitive Allele-Specific PCR) method. Results: The distributions of the AA, GG, and AG genotypes of PRDM16 (rs2651899) polymorphism were 0.19, 0.26 and 0.54, respectively. While the distribution of the mutated allele A was 0.7 in the obese group comparing to 0.34 in the non-obese group. Participants with the mutated genotypes, AA and AG, of PRDM16 (rs2651899) polymorphism were significantly more likely to be obese as compared to participants with wild type genotype (OR = 21, 95% CI = 5.4190 to 84.4231, p value < 0.0001 and OR = 44.6, 95% CI = 11.5984 to 172.0157, p value < 0.0001, respectively). The wild type GG genotype of this polymorphism was associated with higher blood cholesterol, HDL and LDL but lower blood triglyceride compared with the mutated genotypes (p = 0.003, p = 0.008, p = 0.02 and p = 0.003, respectively). In contrast, PDE4D (rs295978) polymorphism was not associated with risk of obesity and had no effects on blood lipids profile. Conclusions: We found that the PRDM16 polymorphism (rs2651899) is a risk factor for obesity and influence blood lipids profiles significantly in Saudi population. While the PDE4D (rs295978) polymorphism didn’t show significant effect on risk of obesity or blood lipids profiles

Additional file 1 of Tunisian Artemisia campestris L.: a potential therapeutic agent against myeloma - phytochemical and pharmacological insights

Supplementary Material

FXR-deficiency confers increased susceptibility to torpor.

International audienceThe role of the nuclear receptor FXR in adaptive thermogenesis was investigated using FXR-deficient mice. Despite elevated serum bile acid concentrations and increased mRNA expression profiles of thermogenic genes in brown adipose tissue, FXR-deficiency did not alter energy expenditure under basal conditions. However, FXR-deficiency accelerated the fasting-induced entry into torpor in a leptin-dependent manner. FXR-deficient mice were also extremely cold-intolerant. These altered responses may be linked to a more rapid decrease in plasma concentrations of metabolic fuels (glucose, triglycerides) thus impairing uncoupling protein 1-driven thermogenesis. These results identify FXR as a modulator of energy homeostasis

Comprehensive molecular characterization of human adipocytes reveals a transient brown phenotype

International audienceAbstractBackgroundFunctional brown adipose tissue (BAT), involved in energy expenditure, has recently been detected in substantial amounts in adults. Formerly overlooked BAT has now become an attractive anti-obesity target.Methods and resultsMolecular characterization of human brown and white adipocytes, using a myriad of techniques including high-throughput RNA sequencing and functional assays, showed that PAZ6 and SW872 cells exhibit classical molecular and phenotypic markers of brown and white adipocytes, respectively. However, the pre-adipocyte cell line SGBS presents a versatile phenotype. A transit expression of classical brown markers such as UCP1 and PPARγ peaked and declined at day 28 post-differentiation initiation. Conversely, white adipocyte markers, including Tcf21, showed reciprocal behavior. Interestingly, leptin levels peaked at day 28 whereas the highest adiponectin mRNA levels were detected at day 14 of differentiation. Phenotypic analysis of the abundance and shape of lipid droplets were consistent with the molecular patterns. Accordingly, the oxidative capacity of SGBS adipocytes peaked on differentiation day 14 and declined progressively towards differentiation day 28.ConclusionsOur studies have unveiled a new phenotype of human adipocytes, providing a tool to identify molecular gene expression patterns and pathways involved in the conversion between white and brown adipocytes

Antibacterial, antioxidant and photocatalytic activity of novel Rubus ellipticus leaf mediated silver nanoparticles

Nanotechnology is an emerging field of science that has significant applications in applied sciences. In this study, silver nanoparticles (SNPs) were synthesized utilizing the leaf filtrate of Rubus ellipticus. SNPs were characterized using UV–visible spectroscopy, scanning electron microscopy, energy dispersive X-ray spectroscopy, and X-ray diffraction patterns to determine their morphology and chemical composition. The surface plasmon resonance of SNPs revealed a peak at 415 nm. The synthesized SNPs were mainly spherical crystals with an average size of 21.43 nm. When compared to plant extract and positive controls (AgNO3 and penicillin), SNPs demonstrated significant bactericidal activity against all the tested bacteria (gram-positive and gram-negative). The most effective bactericidal activity was found against Pseudomonas aeruginosa, with a minimum inhibitory concentration of 1.25 µg/mL. In addition, a dose-dependent antioxidant activity of SNPs was found against the 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical with an average IC50 value of 72.84 µg/mL. The photocatalytic activity of Methylene blue (MB) dye decomposition under sunlight was studied. The results showed that MB degraded by 98 % after 150 min in the sun. Overall, the findings of this study indicate that R. ellipticus biosynthesized SNPs may have bactericidal and photocatalytic effects

The supramammillary nucleus and the claustrum activate the cortex during REM sleep

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The Farnesoid X Receptor Regulates Adipocyte Differentiation and Function by Promoting Peroxisome Proliferator-activated Receptor-γ and Interfering with the Wnt/β-Catenin Pathways*

The bile acid receptor farnesoid X receptor (FXR) is expressed in adipose tissue, but its function remains poorly defined. Peroxisome proliferator-activated receptor-γ (PPARγ) is a master regulator of adipocyte differentiation and function. The aim of this study was to analyze the role of FXR in adipocyte function and to assess whether it modulates PPARγ action. Therefore, we tested the responsiveness of FXR-deficient mice (FXR−/−) and cells to the PPARγ activator rosiglitazone. Our results show that genetically obese FXR−/−/ob/ob mice displayed a resistance to rosiglitazone treatment. In vitro, rosiglitazone treatment did not induce normal adipocyte differentiation and lipid droplet formation in FXR−/− mouse embryonic fibroblasts (MEFs) and preadipocytes. Moreover, FXR−/− MEFs displayed both an increased lipolysis and a decreased de novo lipogenesis, resulting in reduced intracellular triglyceride content, even upon PPARγ activation. Retroviral-mediated FXR re-expression in FXR−/− MEFs restored the induction of adipogenic marker genes during rosiglitazone-forced adipocyte differentiation. The expression of Wnt/β-catenin pathway and target genes was increased in FXR−/− adipose tissue and MEFs. Moreover, the expression of several endogenous inhibitors of this pathway was decreased early during the adipocyte differentiation of FXR−/− MEFs. These findings demonstrate that FXR regulates adipocyte differentiation and function by regulating two counteracting pathways of adipocyte differentiation, the PPARγ and Wnt/β-catenin pathways