Induction and Reversal of beta-cell dysfunction

INTRODUCTION: Targeting β-cell failure could prevent, delay or even partially reverse Type 2 Diabetes. However, development of such drugs is limited as the molecular pathogenesis is complex and incompletely understood. Further, while β-cell failure can be modelled experimentally only some of the molecular changes will be pathogenic. Therefore, we used a novel approach to identify molecular pathways that are not only changed in a diabetes-like state but are reversible and can be targeted by drugs. METHODS: INS1E cells were cultured in high glucose (20 mM) for 72 hrs or high glucose for an initial 24 hrs followed by drug addition (exendin-4, metformin and sodium salicylate) for the remaining 48 hrs. RNAseq (Illumina TruSeq), Gene Set Enrichment and Pathway Analyses (using Broad Institute, Reactome, KEGG and Biocarta platforms) was used to identify changes in molecular pathways. RESULTS: High glucose decreased function and increased apoptosis in INS1E cells with drugs partially reversing these effects. High glucose resulted in upregulation of 109 pathways while drug treatment downregulated 44 pathways with 21 pathways in common. Interestingly while hyperglycaemia extensively upregulated metabolic pathways, they were not altered with drug treatment, rather pathways involved in the cell cycle featured more heavily. CONCLUSION: GSEA for hyperglycaemia identified many known pathways validating the applicability of our cell model to human disease. However, only a fraction of these pathways were downregulated with drug treatment, highlighting the importance of considering druggable pathways. Overall, this provides a powerful approach and resource for identifying appropriate targets for the development of β-cell drugs. INS-1E cells that were cultured in normal glucose (NG [or LG], 11.1 mM glucose) for 72 hours, high glucose (HG, 20mM glucose) for 72 hours or high glucose for an initial 24 hours followed by the addition of drugs (50 nM Exendin-4, 250 μM metformin and 250 μM sodium salicylate) for the remaining 48 hrs (HG+drugs).