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Title: Neuregulin 4 Downregulation Induces Insulin Resistance in 3T3-L1 Adipocytes through Inflammation and Autophagic Degradation of GLUT4 Vesicles
Author: Díaz-Sáez, Francisco
Blanco-Sinfreu, Carla
Archilla-Ortega, Adrià
Sebastián Muñoz, David
Romero, Montserrat
Hernández-Alvarez, María Isabel
Mora Fayos, Sílvia
Testar, Xavier
Ricart, Wifredo
Fernández-Real Lemos, José Manuel
Moreno-Navarrete, José María
Aragonés, Julián
Camps Camprubí, Marta
Zorzano Olarte, Antonio
Gumà i Garcia, Anna Maria
Keywords: Resistència a la insulina
Receptors d'insulina
Insulin resistance
Insulin receptors
Issue Date: 30-Nov-2021
Publisher: MDPI
Abstract: The adipokine Neuregulin 4 (Nrg4) protects against obesity-induced insulin resistance. Here, we analyze how the downregulation of Nrg4 influences insulin action and the underlying mechanisms in adipocytes. Validated shRNA lentiviral vectors were used to generate scramble (Scr) and Nrg4 knockdown (KD) 3T3-L1 adipocytes. Adipogenesis was unaffected in Nrg4 KD adipocytes, but there was a complete impairment of the insulin-induced 2-deoxyglucose uptake, which was likely the result of reduced insulin receptor and Glut4 protein. Downregulation of Nrg4 enhanced the expression of proinflammatory cytokines. Anti-inflammatory agents recovered the insulin receptor, but not Glut4, content. Proteins enriched in Glut4 storage vesicles such as the insulin-responsive aminopeptidase (IRAP) and Syntaxin-6 as well as TBC1D4, a protein involved in the intracellular retention of Glut4 vesicles, also decreased by Nrg4 KD. Insulin failed to reduce autophagy in Nrg4 KD adipocytes, observed by a minor effect on mTOR phosphorylation, at the time that proteins involved in autophagy such as LC3-II, Rab11, and Clathrin were markedly upregulated. The lysosomal activity inhibitor bafilomycin A1 restored Glut4, IRAP, Syntaxin-6, and TBC1D4 content to those found in control adipocytes. Our study reveals that Nrg4 preserves the insulin responsiveness by preventing inflammation and, in turn, benefits the insulin regulation of autophagy.
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It is part of: International Journal of Molecular Sciences, 2021, vol. 22, num. 23, p. 1-18
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ISSN: 1661-6596
Appears in Collections:Articles publicats en revistes (Bioquímica i Biomedicina Molecular)

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