Possible protective effect of membrane lipid rafts against interleukin-1β-mediated anti-proliferative effect in INS-1 cells
Authors: René Gross
Caroline Guzman
Sylvie Peraldi-Roux
Myriam Chentouf
Anne Dominique Lajoix
Moustafa Hamze
Journal: PLoS ONE (2014)
Discipline: Multidisciplinary
Keywords: pancreatic islets; IL-1β; lipid rafts; insulin secretion; apoptosis
Affiliations: Université de Montpellier 1 (UM1), EA 7288, Centre de Pharmacologie et Innovation pour le Diabète (CPID), Faculté de Pharmacie, Montpellier, France., Université de Montpellier 1 (UM1), EA 7288, Centre de Pharmacologie et Innovation pour le Diabète (CPID), Faculté de Pharmacie, Montpellier, France; Université de Montpellier 1 (UM1), EA 7288, Centre National pour la recherche scientifique (CNRS), Centre de Pharmacologie et Innovation pour le Diabète (CPID), Faculté de Pharmacie, Montpellier, France.

Abstract:  We recently reported that pancreatic islets from pre-diabetic rats undergo an inflammatory process in which IL-1β takes part and controls β-cell function. In the present study, using the INS-1 rat pancreatic β-cell line, we investigated the potential involvement of membrane-associated cholesterol-enriched lipid rafts in IL-1β signaling and biological effects on insulin secretion, β-cell proliferation and apoptosis. We show that, INS-1 cells exposure to increasing concentrations of IL-1β leads to a progressive inhibition of insulin release, an increase in the number of apoptotic cells and a dose-dependent decrease in pancreatic β-cell proliferation. Disruption of membrane lipid rafts markedly reduced glucose-stimulated insulin secretion but did not affect either cell apoptosis or proliferation rate, demonstrating that membrane lipid raft integrity is essential for β-cell secretory function. In the same conditions, IL-1β treatment of INS-1 cells led to a slight further decrease in insulin secretion for low concentrations of the cytokine, and a more marked one, similar to that observed in normal cells for higher concentrations. These effects occurred together with an increase in iNOS expression and surprisingly with an upregulation of tryptophane hydroxylase and protein Kinase C in membrane lipid rafts suggesting that compensatory mechanisms develop to counteract IL-1β inhibitory effects. We also demonstrate that disruption of membrane lipid rafts did not prevent cytokine-induced cell death recorded after exposure to high IL-1β concentrations. Finally, concerning cell proliferation, we bring strong evidence that membrane lipid rafts exert a protective effect against IL-1β anti-proliferative effect, possibly mediated at least partly by modifications in ERK and PKB expression/activities. Our results 1) demonstrate that IL-1β deleterious effects do not require a cholesterol-dependent plasma membrane compartmentalization of IL-1R1 signaling and 2) confer to membrane lipid rafts integrity a possible protective function that deserves to be considered in the context of inflammation and especially T2D pathogenesis. 

Retracted: No

PubPeer comments:
 Figure 1c. Much more similar than you would expect. ![file] , 
 This paper was found during a systematic screen of biomedical papers for image duplications, as published in Bik et al., mBio (2016), doi: 10.1128 mBio.00809-16, https: journals.asm.org doi 10.1128 mBio.00809-16. This same concern as raised in comment #1 has been shared with the journal in October 2015, with a friendly reminder in 2016. No update yet. ,