Nucleic Acids Research Advance Access originally published online on March 5, 2009
Nucleic Acids Research 2009 37(8):2529-2538; doi:10.1093/nar/gkp122
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Nucleic Acids Research, 2009, Vol. 37, No. 8 2529-2538
© 2009 The Author(s)
This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/2.0/uk/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.
Gene Regulation, Chromatin and Epigenetics |
The Krüppel-like zinc finger protein Glis3 directly and indirectly activates insulin gene transcription
1Diabetes and Endocrinology Research Center, Division of Diabetes and Endocrinology, Department of Medicine and Department of Molecular & Cellular Biology, Baylor College of Medicine, Houston, TX 77030 and 2St Luke's Episcopal Hospital, Houston, TX, USA
*To whom correspondence should be addressed. Tel: +1 713 798 4478; Fax: +1 713 798 8764; Email: lchan{at}bcm.edu
Received October 16, 2008. Revised February 13, 2009. Accepted February 14, 2009.
Glis3 is a member of the Krüppel-like family of transcription factors and is highly expressed in islet β cells. Mutations in GLIS3 cause the syndrome of neonatal diabetes and congenital hypothyroidism (NDH). Our aim was to examine the role of Glis3 in β 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 β cell.