Taurine Treatment Modulates Circadian Rhythms in Mice Fed A High Fat Diet

Close ties have been made among certain nutrients, obesity, type 2 diabetes and circadian clocks. Among nutrients, taurine has been documented as being effective against obesity and type 2 diabetes. However, the impact of taurine on circadian clocks has not been elucidated. We investigated whether taurine can modulate or correct disturbances in daily rhythms caused by a high-fat diet in mice. Male C57BL/6 mice were divided in four groups: control (C), control + taurine (C+T), high-fat diet (HFD) and HFD + taurine (HFD+T). They were administered 2% taurine in their drinking water for 10 weeks. Mice were euthanized at 6:00, 12:00, 18:00, and 24:00. HFD mice increased body weight, visceral fat and food intake, as well as higher levels of glucose, insulin and leptin, throughout the 24 h. Taurine prevented increments in food intake, body weight and visceral fat, improved glucose tolerance and insulin sensitivity and reduced disturbances in the 24 h patterns of plasma insulin and leptin. HFD downregulated the expression of clock genes Rev-erbα, Bmal1, and Per1 in pancreatic islets. Taurine normalized the gene and protein expression of PER1 in beta-cells, which suggests that it could be beneficial for the correction of daily rhythms and the amelioration of obesity and diabetes

Les anticorps anti-thyroperoxydase (de l'identification de la région immuno-dominante de la thyroperoxydase à l'utilisation du potentiel cytotoxique des anticorps anti-thyropéroxydase dans les cancers thyroïdiens)

Outre leur rôle de marqueur des maladies auto-immunes thyroïdiennes (MAIT), les auto-anticorps (aAc) anti-thyroperoxydase (TPO) pourraient être impliqués dans la destruction de la glande thyroïde et/ou dans l emballement du processus auto-immuns. Ils reconnaissent à la surface de la TPO des épitopes discontinus et majoritairement conformationnels regroupés en deux domaines restreints A et B, définissant la région immuno-dominante (RID). Notre équipe a participé à la caractérisation de cette RID, tout d abord en produisant des aAc recombinants humains anti-TPO spécifiques des aAc de patients atteints de MAIT. Ces aAc recombinants ont été caractérisés au niveau génétique, épitopique et terme d affinité vis-à-vis de la TPO. L utilisation de l un de ces aAc recombinant produit sous forme d Immunoglobuline entière et nommé T13 a permis de définir à la surface de la TPO quatre régions (353-363, 377-386, 713-720 et 766-775) impliquées dans la reconnaissance de la TPO par cet aAc recombinant humain anti-TPO mais également des aAc de patients.Notre étude de la région 353-363, par mutagénèse dirigée où chaque acide aminé est muté ponctuellement en Alanine, a permis de déterminer les résidus impliqués dans l interaction aAc/TPO. Après production des protéines TPO mutées, l étude de la liaison de trois aAc recombinants humains anti-TPO (T13, B4 et ICA1) et des aAc de patients atteints de MAIT a permis d identifier les résidus critiques de cette région : Histidine en position 353 (H353), Acide Aspartique 358 (D358), Arginine 361 (R361). La caractérisation de la RID devrait nous permettre d expliquer le mode de présentation de la TPO au système immunitaire lors de l apparition des MAIT. Le potentiel destructeur des aAc anti-TPO sur la glande thyroïde passe par des mécanismes de cytotoxicité à médiation cellulaire (ADCC) et/ou dépendante du Complément (CDC). Les aAc anti-TPO sont capable de lyser de cellules thyroïdiennes issues de cultures primaires en présence d une source de Complément via la voie classique (après fixation de la fraction C1q du Complément) ou via l activation de cellules effectrices, les monocytes/macrophages capables d infiltrer la thyroïde. Ce mécanisme d ADCC passerait par l activation des récepteurs Fc RI (CD64) et/ou Fc RII (CD32) exprimés par les monocytes/macrophages. Puisque les aAc de patients atteints de MAIT sont capables d exercer une activité cytotoxique, il serait intéressant de pouvoir utiliser ce potentiel destructeur afin de cibler et détruire spécifiquement les cellules cancéreuses thyroïdiennes exprimant la thyroperoxydase (tumeur primaire ou métastases). Afin de pouvoir être utilisé pour la mise en place d une immunothérapie anti-cancéreuse, un aAc recombinant humain anti-TPO produit dans le système baculovirus/cellule d insecte a été sous-cloné et exprimé dans un autre système d expression (cellules CHO). Ces aAc recombinants anti-TPO ainsi que des aAc de patients ont été utilisés dans des tests de cytotoxicité. Ils ont la capacité de lyser les cellules d une lignée de cancer papillaire thyroïdien par des mécanismes de cytotoxicité cellulaire et/ou dépendant du complément. Ces résultats encourageants pourraient permettre l émergence d une thérapie complémentaire pour traiter les cancers thyroïdiens.MONTPELLIER-BU Pharmacie (341722105) / SudocSudocFranceF

Targeting type 2 diabetes: lessons from a knockout model of insulin receptor substrate 2

International audienceInsulin receptor substrate 2 (IRS2) is a widely expressed protein that regulates crucial biological processes including glucose metabolism, protein synthesis, and cell survival. IRS2 is part of the insulin - insulin-like growth factor (IGF) signaling pathway and mediates the activation of the phosphotidylinositol 3-kinase (PI3K)-Akt and the Ras-mitogen-activated protein kinase (MAPK) cascades in insulin target tissues and in the pancreas. The best evidence of this is that systemic elimination of the Irs2 in mice (Irs2(-/-)) recapitulates the pathogenesis of type 2 diabetes (T2D), in that diabetes arises as a consequence of combined insulin resistance and beta-cell failure. Indeed, work using this knockout mouse has confirmed the importance of IRS2 in the control of glucose homeostasis and especially in the survival and function of pancreatic beta-cells. These studies have shown that IRS2 is critically required for beta-cell compensation in conditions of increased insulin demand. Importantly, islets isolated from T2D patients exhibit reduced IRS2 expression, which supports the likely contribution of altered IRS2-dependent signaling to beta-cell failure in human T2D. For all these reasons, the Irs2(-/-) mouse has been and will be essential for elucidating the inter-relationship between beta-cell function and insulin resistance, as well as to delineate therapeutic strategies to protect beta-cells during T2D progression

Taurine Treatment Modulates Circadian Rhythms in Mice Fed A High Fat Diet

International audienceClose ties have been made among certain nutrients, obesity, type 2 diabetes and circadian clocks. Among nutrients, taurine has been documented as being effective against obesity and type 2 diabetes. However, the impact of taurine on circadian clocks has not been elucidated. We investigated whether taurine can modulate or correct disturbances in daily rhythms caused by a high-fat diet in mice. Male C57BL/6 mice were divided in four groups: control (C), control + taurine (C+T), high-fat diet (HFD) and HFD + taurine (HFD+T). They were administered 2% taurine in their drinking water for 10 weeks. Mice were euthanized at 6:00, 12:00, 18:00, and 24:00. HFD mice increased body weight, visceral fat and food intake, as well as higher levels of glucose, insulin and leptin, throughout the 24 h. Taurine prevented increments in food intake, body weight and visceral fat, improved glucose tolerance and insulin sensitivity and reduced disturbances in the 24 h patterns of plasma insulin and leptin. HFD downregulated the expression of clock genes Rev-erbα, Bmal1, and Per1 in pancreatic islets. Taurine normalized the gene and protein expression of PER1 in beta-cells, which suggests that it could be beneficial for the correction of daily rhythms and the amelioration of obesity and diabetes

Taurine Treatment Modulates Circadian Rhythms in Mice Fed A High Fat Diet

Close ties have been made among certain nutrients, obesity, type 2 diabetes and circadian clocks. Among nutrients, taurine has been documented as being effective against obesity and type 2 diabetes. However, the impact of taurine on circadian clocks has not been elucidated. We investigated whether taurine can modulate or correct disturbances in daily rhythms caused by a high-fat diet in mice. Male C57BL/6 mice were divided in four groups: control (C), control + taurine (C+T), high-fat diet (HFD) and HFD + taurine (HFD+T). They were administered 2% taurine in their drinking water for 10 weeks. Mice were euthanized at 6:00, 12:00, 18:00, and 24:00. HFD mice increased body weight, visceral fat and food intake, as well as higher levels of glucose, insulin and leptin, throughout the 24 h. Taurine prevented increments in food intake, body weight and visceral fat, improved glucose tolerance and insulin sensitivity and reduced disturbances in the 24 h patterns of plasma insulin and leptin. HFD downregulated the expression of clock genes Rev-erbα, Bmal1, and Per1 in pancreatic islets. Taurine normalized the gene and protein expression of PER1 in beta-cells, which suggests that it could be beneficial for the correction of daily rhythms and the amelioration of obesity and diabetes

IL-1β and TSH disturb thyroid epithelium integrity in autoimmune thyroid diseases

International audiencePro-inflammatory cytokines such as IL-1β and TNFα are known to affect thyroid function. They stimulate IL-6 secretion and modify epithelium integrity by altering junction proteins. To study the role of cytokines on thyroid epithelia tightness in autoimmune thyroid diseases (AITD), we analyzed the expression profiles of junction proteins (ZO-1, Claudin, JAM-A) and cytokines in human thyroid slices and also investigated the effect of IL-1β on the epithelium integrity in primary cultures of human thyrocytes. Junction proteins expression (ZO-1, Claudin, JAM-A) has been analyzed by immunohistochemistry on thyroid slices and by Western blot on membrane proteins extracted from thyrocytes of patients suffering from Graves and Hashimoto diseases. The high expression of junction proteins we found on Graves' disease thyroid slices as well as in cell membrane extracts acknowledges the tightness of thyroid follicular cells in this AITD. In contrast, the reduced expression of JAM and ZO-1 in thyroid cells from patients suffering from Hashimoto thyroiditis is in agreement with the loss of thyroid follicular cell integrity that occurs in this pathology. Concerning the effects on epithelium integrity of TSH and of the pro-inflammatory cytokine IL-1β in primary cultures of human thyroid cells, TSH appeared able to modify JAM-A localization but without any change in the expression levels of JAM-A, Claudin and ZO-1. Inversely, IL-1β provoked a decrease in the expression of- and a redistribution of both, Claudin and ZO-1 without modifying the expression and sub-cellular distribution patterns of JAM-A in thyroid cells. These results demonstrate (i) that Hashimoto's- and Graves' diseases display different junction proteins expression patterns with a loss of epithelium integrity in the former and (ii) that IL-1β modifies thyroid epithelial tightness of human thyrocytes by altering the expression and localization of junction proteins. Therefore, IL-1β could play a role in the pathogenesis of thyroid autoimmunity

The host cell MAP kinase ERK-2 regulates viral assembly and release by phosphorylating the p6gag protein of HIV-1.

International audienceThe host cell MAP kinase ERK-2 incorporated within human immunodeficiency virus type 1 particles plays a critical role in virus infectivity by phosphorylating viral proteins. Recently, a fraction of the virus incorporated late (L) domain-containing p6(gag) protein, which has an essential function in the release of viral particles from the cell surface, was reported to be phosphorylated by an unknown virus-associated cellular protein kinase (Muller, B., Patschinsky, T., and Krausslich, H. G. (2002) J. Virol. 76, 1015-1024). The present study demonstrates the contribution of the MAP kinase ERK-2 in p6(gag) phosphorylation. According to mutational analysis, a single ERK-2-phosphorylated threonine residue, belonging to a highly conserved phosphorylation MAP kinase consensus site, was identified at position 23 within p6(gag). Substitution by an alanine of the Thr(23) phosphorylable residue within the pNL4.3 molecular clone was found to decrease viral release from various cell types. As observed from electron microscopy experiments, most virions produced from this molecular clone remained incompletely separated from the host cell membrane with an immature morphology and displayed a reduced infectivity in single round infection experiments. Analysis of protein processing by Western blotting experiments revealed an incomplete Pr55(gag) maturation and a reduction in the virion-associated reverse transcriptase proteins was observed that was not related to differences in intracellular viral protein expression. Altogether, these data suggest that phosphorylation of p6(gag) protein by virus-associated ERK-2 is involved in the budding stage of HIV-1 life cycle

Adipose tissue derived-factors impaired pancreatic β-cell function in diabetes

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Effect of ghrelin on the apoptotic deletion rate of different types of cells cultured in vitro

Evidence indicates that ghrelin, an endogenous ligand of the growth hormone secretagogue receptor, controls the growth of several human and rat cell types cultured in vitro. Hence, we have investigated, by using both TUNEL and ELISA assays, the effects of 10(-8) M ghrelin on the basal apoptotic deletion rate of rat osteoblasts and thymocytes, rat and human adrenocortical cells, human umbilical vein endothelial cells, and human aldosteronoma cells cultured in vitro, as well as of the human adrenocortical carcinoma-derived cell lines NCI-H295 and SW-13. Both assays consistently showed that ghrelin did not affect apoptotic rate of normal rat and human cells, but significantly enhanced apoptotic deletion in aldosteronoma, NCI-14295 and SW-13 cell cultures. Due to the central role of apoptosis in the control of tumor growth, these findings, if confirmed in other tumor cell types, could suggest an antitumoral action of ghrelin

Circulating SFRP5 levels are elevated in drug-naïve recently diagnosed type 2 diabetic patients as compared with prediabetic subjects and controls

International audienceBACKGROUND:Secreted frizzled-related protein 5 (SFRP5) has been linked to obesity. Results are conflicting regarding its association with type 2 diabetes (T2D) in humans. We aimed to investigate circulating SFRP5 in prediabetes and T2D and its potential association with parameters of insulin resistance and beta-cell function.METHODS:We studied 70 drug-naïve T2D patients, 70 prediabetic subjects and 70 controls. All subjects were body mass index matched to the T2D patients and overweight or obese. SFRP5, hormones and cytokines levels were measured by ELISA.RESULTS:Serum SFRP5 levels were elevated in T2D patients as compared with prediabetic subjects (median 15.6, interquartile range [9-24.5] ng/mL vs 9.8 [5-14.2] ng/mL, p < 0.001, respectively) and controls (15.6 [9-24.5] ng/mL vs 10.4 [6.7-16.6] ng/mL, P < 0.001, respectively). No differences were found in serum SFRP5 levels between prediabetic subjects and controls (9.8 [5-14.2] ng/mL vs 10.4 [6.7-16.6] ng/mL, p = 0.472, respectively). After adjusting for potential confounders (age, gender, body mass index, triglycerides, high-density lipoprotein cholesterol and blood pressure), T2D was still associated with higher values of SFRP5 as compared with prediabetes in multinomial logistic regression analysis (fully adjusted odds ratio 3.50, 95% confidence interval 1.40-8.79, p = 0.008). The association was more subtle when comparing T2D with normal glucose tolerance state (fully adjusted odds ratio 2.18, 95% confidence interval 0.91-5.21, p = 0.078).CONCLUSIONS:Circulating SFRP5 levels were independently associated with T2D as compared with prediabetes and normal glucose tolerance state