M19 Modulates Skeletal Muscle Differentiation and Insulin Secretion in Pancreatic β-Cells through Modulation of Respiratory Chain Activity

Mitochondrial dysfunction due to nuclear or mitochondrial DNA alterations contributes to multiple diseases such as metabolic myopathies, neurodegenerative disorders, diabetes and cancer. Nevertheless, to date, only half of the estimated 1,500 mitochondrial proteins has been identified, and the function of most of these proteins remains to be determined. Here, we characterize the function of M19, a novel mitochondrial nucleoid protein, in muscle and pancreatic β-cells. We have identified a 13-long amino acid sequence located at the N-terminus of M19 that targets the protein to mitochondria. Furthermore, using RNA interference and over-expression strategies, we demonstrate that M19 modulates mitochondrial oxygen consumption and ATP production, and could therefore regulate the respiratory chain activity. In an effort to determine whether M19 could play a role in the regulation of various cell activities, we show that this nucleoid protein, probably through its modulation of mitochondrial ATP production, acts on late muscle differentiation in myogenic C2C12 cells, and plays a permissive role on insulin secretion under basal glucose conditions in INS-1 pancreatic β-cells. Our results are therefore establishing a functional link between a mitochondrial nucleoid protein and the modulation of respiratory chain activities leading to the regulation of major cellular processes such as myogenesis and insulin secretion

Excessive Food Intake, Obesity and Inflammation Process in Zucker fa/fa Rat Pancreatic Islets

Inappropriate food intake-related obesity and more importantly, visceral adiposity, are major risk factors for the onset of type 2 diabetes. Evidence is emerging that nutriment-induced β-cell dysfunction could be related to indirect induction of a state of low grade inflammation. Our aim was to study whether hyperphagia associated obesity could promote an inflammatory response in pancreatic islets leading to ß-cell dysfunction. In the hyperphagic obese insulin resistant male Zucker rat, we measured the level of circulating pro-inflammatory cytokines and estimated their production as well as the expression of their receptors in pancreatic tissue and β-cells. Our main findings concern intra-islet pro-inflammatory cytokines from fa/fa rats: IL-1β, IL-6 and TNFα expressions were increased; IL-1R1 was also over-expressed with a cellular redistribution also observed for IL-6R. To get insight into the mechanisms involved in phenotypic alterations, abArrays were used to determine the expression profile of proteins implicated in different membrane receptors signaling, apoptosis and cell cycle pathways. Despite JNK overexpression, cell viability was unaffected probably because of decreases in cleaved caspase3 as well as in SMAC/DIABLO and APP, involved in the induction and amplification of apoptosis. Concerning β-cell proliferation, decreases in important cell cycle regulators (Cyclin D1, p35) and increased expression of SMAD4 probably contribute to counteract and restrain hyperplasia in fa/fa rat islets. Finally and probably as a result of IL-1β and IL-1R1 increased expressions with sub-cellular redistribution of the receptor, islets from fa/fa rats were found more sensitive to both stimulating and inhibitory concentrations of the cytokine; this confers some physiopathological relevance to a possible autocrine regulation of β-cell function by IL-1β. These results support the hypothesis that pancreatic islets from prediabetic fa/fa rats undergo an inflammatory process. That the latter could contribute to β-cell hyperactivity/proliferation and possibly lead to progressive β-cell failure in these animals, deserves further investigations

NO synthase et cellule b pancréatique

MONTPELLIER-BU Pharmacie (341722105) / SudocSudocFranceF

Maitrise de la production et qualification des lots de protéines recombinantes d un point de vue viral

MONTPELLIER-BU Pharmacie (341722105) / SudocSudocFranceF

Implication d'une isoforme de la NO-synthase neuronale dans la sécrétion d'insuline : rôle modulateur de l'intéraction avec son inhibiteur endogène, PIN

Les No synthases ( NOS) sont les enzymes qui synthétisent du NO à partir de leur substrat, l'arginine. Il existe trois isoformes de NOS : deux NOS constitutives, la NOS neuronale (nNOS) et la NOS endothéliale et une NOS inductible. Nous avons démontré l'expression d'une isoforme de la NOS neuronale dans les cellules ß pancréatiques de rat et de l'homme. Cette enzyme est fortement localisée au niveau des granules de sécrétion d'insuline, et plus faiblement dans les mitochondries et le noyau. Dans le pancréas isolé et perfusé de rat, cette nNOS contrôle la sécrétion d'insuline induite par le glucose et l'arginine grâce à deux activités : une production de NO et une activité cytochrome c réductase par l'intermédiaire d'une interaction directe avec le cytochrome c. L'effet modulateur négatif du NO est retrouvé dans une lignée cellulaire ß pure, les cellules INS-1. de plus, en utilisant deux types d'inhibiteurs pharmacologique de la nNOS, nous avons également démontré que l'état de dimérisation de l'enzyme influait sur la cinétique de la sécrétion d'insuline induite par le glucose et sur la sensibilité des cellules ß au NO.Nous nous sommes également intéressé à l'inhibiteur endogène de la nNOS, PIN ( Protein Inhibitor of Neuronal NOS ). Nous avons démontré la présence de PIN dans les cellules ß pancréatiques de rat et de l'homme. Cet inhibiteur est essentiellement associé au granules sécrétoires d'insuline et semble avoir un rôle modulateur positif de la sécrétion d'insuline dans les cellules INS-1. Nous avons ensuite disséqué les interactions entre les deux protéines et démontré l'existence de deux zones d'interactions, une de très forte affinité plus faible, influencées par le pH et la force ionique du milieu.Enfin, nous avons réalisé un brevet d'invention proposant d'utiliser les interactions PIN-nNOS comme cible pour la découverte de nouvelles molécules destinées à traiter les états prédiabétiques.MONTPELLIER-BU Pharmacie (341722105) / SudocPARIS-BIUP (751062107) / SudocSudocFranceF

Les anticorps monoclonaux, enjeux thérapeutiques, systèmes de productions et futurs développement cliniques

MONTPELLIER-BU Pharmacie (341722105) / SudocSudocFranceF

Enjeux internationaux du développement des biosimilaires, réglementations et orientations des politiques de santé publique (focus sur le domaine du diabète)

MONTPELLIER-BU Pharmacie (341722105) / SudocSudocFranceF

Place du Gardasil® dans la prévention des cancers génitaux liés au papillomavirus chez la femme

MONTPELLIER-BU Pharmacie (341722105) / SudocSudocFranceF

P2 purinergic signalling in the pancreatic beta-cell: control of insulin secretion and pharmacology.

International audienceExtracellular adenosine triphosphate is able to modulate pancreatic beta-cell function, acting on P2 purinergic ionotropic (P2X) and metabotropic (P2Y) receptors. Physiologically, ATP entrains beta-cells into a common rhythm by coordinating Ca(2+) oscillations; it plays a central role in insulin secretion pulsatility. ATP also triggers a positive feedback signal amplifying glucose-induced insulin release, which argues for a potential pharmacological application. ATP has consistently been shown to increase cytoplasmic free calcium concentration, notably in human tissue. Acting on P2X receptors, of which different molecular subtypes are expressed in beta-cells, it leads to a transient insulin release that may involve a closure of K(ATP) channels or a rapidly decaying inward current. Activation of G-protein-coupled P2Y receptors triggers different signalling pathways and amplifies insulin release in a glucose-dependent way. It has recently been shown that pancreatic beta-cells express different molecular subtypes of receptors, which may explain the complex interaction of P2Y ligands on high- and low-affinity binding sites. Despite the complexity of this purinergic pharmacology, consistent pre-clinical data suggest the potential of P2Y receptor agonists as drug candidates for type 2 diabetes

Multi-Step Synthesis and Biological Evaluation of Analogues of Insulin Secretagogue (2S,3R,4S)-4-Hydroxyisoleucine

International audienceA series of stereochemically defined analogues of (2S,3R,4S)4-hydroxyisoleucine and related alpha-hydroxy acids have been prepared by multi-step routes from D-glucose, whereas ketolization between TBDMS-protected hydroxypropanone and ethyl isocyanoacetate led to racemic analogues. Bioassays showed that of eight newly synthesized Compounds, two of them presented an interesting statistical trend to increase glucose-induced insulin secretion when tested in isolated rat pancreatic islets in the presence of 8.3 mM glucose and at a concentration of 200 pm, which has previously been shown to be effective for (2S,3R,4S)-4-hydroxyisoleucine, ((C) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009