The Systemic Control of Growth, Physiology, and Behavior by TOR Signaling in Drosophila

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Brain adiponectin signaling controls peripheral insulin response in Drosophila.

International audienceThe brain plays a key role in energy homeostasis, detecting nutrients, metabolites and circulating hormones from peripheral organs and integrating this information to control food intake and energy expenditure. Here, we show that a group of neurons in the Drosophila larval brain expresses the adiponectin receptor (AdipoR) and controls systemic growth and metabolism through insulin signaling. We identify glucose-regulated protein 78 (Grp78) as a circulating antagonist of AdipoR function produced by fat cells in response to dietary sugar. We further show that central AdipoR signaling inhibits peripheral Juvenile Hormone (JH) response, promoting insulin signaling. In conclusion, we identify a neuroendocrine axis whereby AdipoR-positive neurons control systemic insulin response

Drosophila ALS regulates growth and metabolism through functional interaction with insulin-like peptides.

In metazoans, factors of the insulin family control growth, metabolism, longevity, and fertility in response to environmental cues. In Drosophila, a family of seven insulin-like peptides, called Dilps, activate a common insulin receptor. Some Dilp peptides carry both metabolic and growth functions, raising the possibility that various binding partners specify their functions. Here we identify dALS, the fly ortholog of the vertebrate insulin-like growth factor (IGF)-binding protein acid-labile subunit (ALS), as a Dilp partner that forms a circulating trimeric complex with one molecule of Dilp and one molecule of Imp-L2, an IgG-family molecule distantly related to mammalian IGF-binding proteins (IGFBPs). We further show that dALS antagonizes Dilp function to control animal growth as well as carbohydrate and fat metabolism. These results lead us to propose an evolutionary perspective in which ALS function appeared prior to the separation between metabolic and growth effects that are associated with vertebrate insulin and IGFs

Analysis of the hypoxia-sensing pathway in Drosophila melanogaster

The mechanism by which hypoxia induces gene transcription involves the inhibition of HIF-1α (hypoxia-inducible factor-1 α subunit) PHD (prolyl hydroxylase) activity, which prevents the VHL (von Hippel-Lindau)-dependent targeting of HIF-1α to the ubiquitin/proteasome pathway. HIF-1α thus accumulates and promotes gene transcription. In the present study, first we provide direct biochemical evidence for the presence of a conserved hypoxic signalling pathway in Drosophila melanogaster. An assay for 2-oxoglutarate-dependent dioxygenases was developed using Drosophila embryonic and larval homogenates as a source of enzyme. Drosophila PHD has a low substrate specificity and hydroxylates key proline residues in the ODD (oxygen-dependent degradation) domains of human HIF-1α and Similar, the Drosophila homologue of HIF-1α. The enzyme promotes human and Drosophila [(35)S]VHL binding to GST (glutathione S-transferase)–ODD-domain fusion protein. Hydroxylation is enhanced by proteasomal inhibitors and was ascertained using an anti-hydroxyproline antibody. Secondly, by using transgenic flies expressing a fusion protein that combined an ODD domain and the green fluorescent protein (ODD–GFP), we analysed the hypoxic cascade in different embryonic and larval tissues. Hypoxic accumulation of the reporter protein was observed in the whole tracheal tree, but not in the ectoderm. Hypoxic stabilization of ODD–GFP in the ectoderm was restored by inducing VHL expression in these cells. These results show that Drosophila tissues exhibit different sensitivities to hypoxia

Control of Metabolism and Growth Through Insulin-Like Peptides in Drosophila

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Responsabilité sociétale et environnementale : quelles compétences pour les professionnels des bibliothèques ?

Nouveau rendez-vous annuel de l’Enssib, le Printemps des Métiers est une journée d’étude consacrée à l’évolution des métiers des bibliothèques et de la documentation. Chaque édition sera consacrée à une thématique qui interroge et bouscule les pratiques professionnelles. Qu’est-ce que ces évolutions impliquent en matière de compétences pour les professionnels des bibliothèques et de la documentation relevant de l’enseignement supérieur, de la recherche comme de la lecture publique ? Par des retours d’expériences, études, restitutions d’enquête et mises en perspective, le Printemps des Métiers vise à favoriser une synthèse des approches et offrir un espace d’échanges prospectif. Pour cette première édition, le thème retenu est la responsabilité sociétale et environnementale. Gestion de bâtiment, numérique responsable, égalité des chances, bien-être et santé, consommation responsable… En tant qu’espaces physiques, pourvoyeurs de documentation, services de médiation ou même acheteurs, les bibliothèques et services documentaires sont par nature impactés par les enjeux de la responsabilité sociétale et environnementale, dont s’emparent d’ailleurs largement les organisations dont ils dépendent. Quelles compétences sont en jeu ? Comment les soutenir et accompagner leur développement