Romano Regazzi

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To define the role of the Rab3-interacting molecule RIM in exocytosis we searched for additional binding partners of the protein. We found that the two C(2) domains of RIM display properties analogous to those of the C(2)B domain of synaptotagmin-I. Thus, RIM-C(2)A and RIM-C(2)B bind in a Ca(2+)-independent manner to alpha1B, the pore-forming subunit of(More)
OBJECTIVE Pancreatic beta-cells exposed to proinflammatory cytokines display alterations in gene expression resulting in defective insulin secretion and apoptosis. MicroRNAs are small noncoding RNAs emerging as key regulators of gene expression. Here, we evaluated the contribution of microRNAs to cytokine-mediated beta-cell cytotoxicity. RESEARCH DESIGN(More)
Several approaches were used to test the hypothesis proposing a role for acyl-CoA esters in nutrient-induced insulin release (Prentki, M., and Matschinsky, F. M. (1987) Physiol. Rev. 67, 1185-1248; Corkey, B. E., Glennon, M. C., Chen, K. S., Deeney, J. T., Matschinsky, F. M., and Prentki, M. (1989) J. Biol. Chem. 264, 21608-21612). Exogenous saturated long(More)
Nutrient metabolism was examined with regard to insulin secretion in purified rat islet beta- and non-beta-cells, beta-cell lines, and hepatocytes. Lactate dehydrogenase (LDH) activity (nanomoles.min-1.mg protein-1) was remarkably low in the glucose-sensitive INS-1 cell line (15.7) and in beta-cells (22.3). Thus, beta-cell LDH was respectively 8-, 122-,(More)
Rab27a is a GTPase associated with insulin-containing secretory granules of pancreatic beta-cells. Selective reduction of Rab27a expression by RNA interference did not alter granule distribution and basal secretion but impaired exocytosis triggered by insulin secretagogues. Screening for potential effectors of the GTPase revealed that the Rab27a-binding(More)
Fine-tuning of insulin secretion from pancreatic beta-cells participates in blood glucose homeostasis. Defects in this process can lead to chronic hyperglycemia and diabetes mellitus. Several proteins controlling insulin exocytosis have been identified, but the mechanisms regulating their expression remain poorly understood. Here, we show that two(More)
The small GTPases Rab3 and Rab27 are associated with secretory granules of pancreatic beta-cells and regulate insulin exocytosis. In this study, we investigated the role of Noc2, a potential partner of these two GTPases, in insulin secretion. In the beta-cell line INS-1E wild-type Noc2, Noc265E, and Noc258A, a mutant capable of interacting with Rab27 but(More)
Astrocytes are the most abundant glial cell type in the brain. Although not apposite for long-range rapid electrical communication, astrocytes share with neurons the capacity of chemical signaling via Ca(2+)-dependent transmitter exocytosis. Despite this recent finding, little is known about the specific properties of regulated secretion and vesicle(More)
VAMP proteins are important components of the machinery controlling docking and/or fusion of secretory vesicles with their target membrane. We investigated the expression of VAMP proteins in pancreatic beta-cells and their implication in the exocytosis of insulin. cDNA cloning revealed that VAMP-2 and cellubrevin, but not VAMP-1, are expressed in rat(More)
We examined the presence of small molecular mass GTP-binding proteins of the Rab3 family in different insulin-secreting cells. Rab3B and Rab3C were identified by western blotting in rat and in human pancreatic islets, in two rat insulin-secreting cell lines, RINm5F and INS-1, as well as in the hamster cell line HIT-T15. In contrast, Rab3A was detected in(More)