PDX1 and ISL1 differentially coordinate with epigenetic modifications to regulate insulin gene expression in varied glucose concentrations

The mechanism of insulin gene transcription control in response to glucose concentration is poorly defined. The islet-restricted transcription factors PDX1 and ISL1 interact with BETA2, activating insulin gene expression. However, their contribution and hierarchical organization in insulin expression control based on glucose concentration remain unknown. We investigated PDX1 and ISL1 regulation of insulin gene expression in pancreatic 13 cells cultured in normal (5 mM/L) and high (25 mM/L) glucose conditions. ISL1 interacted with BETA2 to maintain basic insulin gene transcriptional activity under normal glucose. The ISL1-recruited cofactors SET9 and JMJD3 facilitated insulin gene histone modifications under normal glucose. In high-glucose concentrations, PDX1 formed a complex with BETA2 to enhance insulin gene expression. PDX1 also recruited SET9 and JMJD3 to promote the activation of histone modulation on the insulin promoter. This is the first evidence transcription factors orchestrate epigenetic modifications to control insulin gene expression based on glucose concentration. (C) 2016 The Authors. Published by Elsevier Ireland Ltd.National Natural Science Foundation of China [81170713, 81472022, 81370236, 81371889, 81071675, 81301874]; Natural Science Foundation of Beijing [5122021, 7132051]; Specialized Research Fund for the New Teacher in Doctoral Program of Higher Education [2012001120135]; Leading Academic Discipline Project of Beijing Education Bureau; 111 Project of China [B07001]SCI(E)ARTICLEchunyanzhou@bjmu.edu.cnC38-4842