Molecular mechanisms of insulin exocytosis role of small monomeric GTP-ASES

Détails

Demande d'une copie
ID Serval
serval:BIB_7E4E8309D036
Type
Thèse: thèse de doctorat.
Collection
Publications
Institution
Titre
Molecular mechanisms of insulin exocytosis role of small monomeric GTP-ASES
Auteur⸱e⸱s
Ljubicic S.
Directeur⸱rice⸱s
Regazzi R.
Détails de l'institution
Université de Lausanne, Faculté de biologie et médecine
Adresse
Faculté de biologie et de médecine Université de Lausanne UNIL - Bugnon Rue du Bugnon 21 - bureau 4111 CH-1015 Lausanne SUISSE
Statut éditorial
Acceptée
Date de publication
2010
Langue
anglais
Nombre de pages
120
Notes
REROID:R005739929 ill.
Résumé
SUMMARYInsulin secretion from pancreatic beta-cells is a fundamental condition for the maintenance of blood glucose levels. During the last decades, important components of the molecular machinery controlling hormone release have been characterized. My PhD thesis was dedicated to the study of new signaling pathways regulating insulin exocytosis and in particular to the role of small monomelic guanine triphosphatase or GTPases controlling the last events of hormone release.The first part of my thesis focused on Ras-like (Ral) RalA and RalB proteins. We investigated the mechanisms leading to activation of Ral proteins in pancreatic beta-cells and analyzed their impact on different steps of the insulin-secretory process. Our results have shown that RalA is the predominant isoform expressed in pancreatic islets and insulin-secreting cell lines. Silencing of this GTPase in INS-IE cells by RNA interference led to a decrease in secretagogue-induced hormone release. The activation of the GTPase, followed by FRET imaging, is triggered by increases in intracellular Ca and cAMP. Defective insulin release in cells lacking RalA is associated with a decrease in the secretory granules docked at the plasma membrane, detected by TIRF microscopy and with strong impairment in PLD1 activation in response to secretagogues. RalA was found to be activated by the exchange factor RalGDS, which regulates hormone secretion induced by secretagogues and the docking step of insulin-containing granules at the plasma membrane. In the second part of this work we have shown that a member of the Rab family, Rab37, is present on insulin-containing secretory granules of pancreatic beta-cells. In addition, our experiments have suggested that Rab37 is required to obtain an optimal insulin secretory response induced by secretogogues and is important for the docking step of insulin-containing granules at the plasma membrane.
Mots-clé
Pancreatic beta-cell, insulin exocytosis, small monomelic GTPases, RalA, Rab37, large dense-core granules, docking, TIRF Microscopy, FRET imaging
Création de la notice
05/04/2011 12:13
Dernière modification de la notice
20/08/2019 15:39
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