Yang Yisheng, Chang Benny Hung-Junn, Samson Susan L, Li Ming V, Chan Lawrence
Diabetes and Endocrinology Research Center, Division of Diabetes and Endocrinology, Department of Medicine, Baylor College of Medicine, Houston, TX 77030, USA.
Nucleic Acids Res. 2009 May;37(8):2529-38. doi: 10.1093/nar/gkp122. Epub 2009 Mar 5.
Glis3 is a member of the Krüppel-like family of transcription factors and is highly expressed in islet beta cells. Mutations in GLIS3 cause the syndrome of neonatal diabetes and congenital hypothyroidism (NDH). Our aim was to examine the role of Glis3 in beta cells, specifically with regard to regulation of insulin gene transcription. We demonstrate that insulin 2 (Ins2) mRNA expression in rat insulinoma 832/13 cells is markedly increased by wild-type Glis3 overexpression, but not by the NDH1 mutant. Furthermore, expression of both Ins1 and Ins2 mRNA is downregulated when Glis3 is knocked down by siRNA. Glis3 binds to the Ins2 promoter in the cell, detected by chromatin immunoprecipitation. Deletion analysis of Ins2 promoter identifies a sequence (5'-GTCCCCTGCTGTGAA-3') from -255 to -241 as the Glis3 response element and binding occur specifically via the Glis3 zinc finger region as revealed by mobility shift assays. Moreover, Glis3 physically and functionally interacts with Pdx1, MafA and NeuroD1 to modulate Ins2 promoter activity. Glis3 also may indirectly affect insulin promoter activity through upregulation of MafA and downregulation of Nkx6-1. This study uncovers a role of Glis3 for regulation of insulin gene expression and expands our understanding of its role in the beta cell.
Glis3是转录因子Krüppel样家族的成员，在胰岛β细胞中高表达。GLIS3基因突变会导致新生儿糖尿病和先天性甲状腺功能减退综合征（NDH）。我们的目的是研究Glis3在β细胞中的作用，特别是在胰岛素基因转录调控方面。我们证明，在大鼠胰岛素瘤832/13细胞中，野生型Glis3过表达可显著增加胰岛素2（Ins2）mRNA的表达，但NDH1突变体则无此作用。此外，当用小干扰RNA敲低Glis3时，Ins1和Ins2 mRNA的表达均下调。通过染色质免疫沉淀检测发现，Glis3在细胞中与Ins2启动子结合。对Ins2启动子的缺失分析确定了从-255至-241的序列（5'-GTCCCCTGCTGTGAA-3'）为Glis3反应元件，迁移率变动分析显示，结合通过Glis3锌指区域特异性发生。此外，Glis3与Pdx1、MafA和NeuroD1在物理和功能上相互作用，以调节Ins2启动子活性。Glis3还可能通过上调MafA和下调Nkx6-1间接影响胰岛素启动子活性。这项研究揭示了Glis3在胰岛素基因表达调控中的作用，并扩展了我们对其在β细胞中作用的理解。
