O-GlcNAcylation of FoxO1 in pancreatic β cells promotes Akt inhibition through an IGFBP1-mediated autocrine mechanism - Archive ouverte HAL Accéder directement au contenu
Article Dans Une Revue FASEB Journal Année : 2014

O-GlcNAcylation of FoxO1 in pancreatic β cells promotes Akt inhibition through an IGFBP1-mediated autocrine mechanism

Résumé

O-GlcNAcylation on serine/threonine is a post-translational modification that controls the activity of nucleocytoplasmic proteins according to glucose availability. We previously showed that O-GlcNAcylation of FoxO1 in liver cells increases its transcriptional activity. In the present study, we evaluated the potential involvement of FoxO1 O-GlcNAcylation in the context of pancreatic β-cell glucotoxicity. FoxO1 was O-GlcNAcylated in INS-1 832/13 β cells and isolated rat pancreatic islets. O-GlcNAcylation of FoxO1 resulted in a 2-fold increase in its transcriptional activity toward a FoxO1 reporter gene and a 3-fold increase in the expression of the insulin-like growth factor-binding protein 1 (Igfbp1) gene at the mRNA level, resulting in IGFBP1 protein oversecretion by the cells. Of note, increased IGFBP1 in the culture medium inhibited the activity of the insulin-like growth factor 1 receptor (IGF1R)/phosphatidyl inositol 3 kinase (PI3K)/Akt pathway. We reveal in this report a novel mechanism by which O-GlcNAcylation inhibits Akt activity through an autocrine mechanism. However, although inhibition of IGFBP1 expression using siRNA restored the PI3 kinase/Akt pathway, it did not rescue INS-1 832/13 cells from high-glucose- or O-glcNAcylation-induced cell death. In contrast, FoxO1 down-regulation by siRNA led to 30 to 60% protection of INS-1 832/13 cells from death mediated by glucotoxic conditions. Therefore, whereas FoxO1 O-GlcNAcylation inhibits Akt through an IGFBP1-mediated autocrine pathway, the deleterious effects of FoxO1 O-GlcNAcylation on cell survival appeared to be independent of this pathway.-Fardini, Y., Masson, E., Boudah, O., Ben Jouira, R., Cosson, C., Pierre-Eugene, C., Kuo, M.-S., Issad, T. O-GlcNAcylation of FoxO1 in pancreatic β cells promotes Akt inhibition through an IGFBP1-mediated autocrine mechanism.
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Dates et versions

hal-01123110 , version 1 (04-03-2015)

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Yann Fardini, Elodie A.Y. Masson, Ouassila Boudah, Rania Ben Jouira, Camille Cosson, et al.. O-GlcNAcylation of FoxO1 in pancreatic β cells promotes Akt inhibition through an IGFBP1-mediated autocrine mechanism. FASEB Journal, 2014, 28 (2), pp.1010-1021. ⟨10.1096/fj.13-238378⟩. ⟨hal-01123110⟩
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