An alternative polyadenylation signal in TCF7L2 generates isoforms that inhibit T cell factor/lymphoid-enhancer factor (TCF/LEF)-dependent target genes

Title: An alternative polyadenylation signal in TCF7L2 generates isoforms that inhibit T cell factor/lymphoid-enhancer factor (TCF/LEF)-dependent target genes
Authors: Locke, JM
Xavier, GDS
Rutter, GA
Harries, LW
Item Type: Journal Article
Abstract: Aims/hypothesis Intronic single nucleotide polymorphisms within the transcription factor 7-like 2 (TCF7L2) gene are associated with risk of type 2 diabetes. It is widely hypothesised that the predisposing variation is involved in cis-regulation of TCF7L2 activity. The aim of this study was to seek evidence for the existence of novel TCF7L2 isoforms encoded within the type 2 diabetes-associated genomic region. Methods We searched expressed sequence tag (EST) databases for novel TCF7L2 transcripts and sought to validate the function and integrity of any isoforms found using a combination of RT-PCR, western blotting and reporter gene techniques. Results Analysis of EST databases suggested the presence of an alternative polyadenylation site located in intron 4 of TCF7L2. We used 3′ rapid amplification of cDNA ends and real-time PCR to validate the integrity of this polyadenylation signal and show its wide use across human tissues. Western blotting results are consistent with the use of this polyadenylation signal to generate novel protein isoforms. The alternative polyadenylation signal results in the production of isoforms that retain the β-catenin binding domain but do not possess the high-mobility group box DNA-binding domain. Promoter–reporter gene assays suggest that these isoforms inhibit TCF7L2-dependent target genes by sequestering β-catenin. Aims/hypothesis Intronic single nucleotide polymorphisms within the transcription factor 7-like 2 (TCF7L2) gene are associated with risk of type 2 diabetes. It is widely hypothesised that the predisposing variation is involved in cis-regulation of TCF7L2 activity. The aim of this study was to seek evidence for the existence of novel TCF7L2 isoforms encoded within the type 2 diabetes-associated genomic region. Methods We searched expressed sequence tag (EST) databases for novel TCF7L2 transcripts and sought to validate the function and integrity of any isoforms found using a combination of RT-PCR, western blotting and reporter gene techniques. Results Analysis of EST databases suggested the presence of an alternative polyadenylation site located in intron 4 of TCF7L2. We used 3′ rapid amplification of cDNA ends and real-time PCR to validate the integrity of this polyadenylation signal and show its wide use across human tissues. Western blotting results are consistent with the use of this polyadenylation signal to generate novel protein isoforms. The alternative polyadenylation signal results in the production of isoforms that retain the β-catenin binding domain but do not possess the high-mobility group box DNA-binding domain. Promoter–reporter gene assays suggest that these isoforms inhibit TCF7L2-dependent target genes by sequestering β-catenin.
Issue Date: 14-Sep-2011
Date of Acceptance: 1-Aug-2011
URI: http://hdl.handle.net/10044/1/50972
DOI: https://dx.doi.org/10.1007/s00125-011-2290-6
ISSN: 0012-186X
Publisher: Springer Verlag
Start Page: 3078
End Page: 3082
Journal / Book Title: Diabetologia
Volume: 54
Issue: 12
Copyright Statement: © The Author(s) 2011. This article is published with open access at Springerlink.com
Sponsor/Funder: Medical Research Council (MRC)
Funder's Grant Number: G0401641
Keywords: Science & Technology
Life Sciences & Biomedicine
Endocrinology & Metabolism
ENDOCRINOLOGY & METABOLISM
Alternative polyadenylation
TCF7L2
Type 2 diabetes
HUMAN PANCREATIC-ISLETS
BETA-CATENIN
TYPE-2
VARIANTS
Alternative Splicing
Base Sequence
Cell Line
Databases, Genetic
Diabetes Mellitus, Type 2
Exons
Expressed Sequence Tags
Gene Expression Regulation
Humans
Intestine, Small
Introns
Molecular Sequence Data
Pancreas
Polyadenylation
Promoter Regions, Genetic
Protein Isoforms
Protein Structure, Tertiary
Signal Transduction
TCF Transcription Factors
Transcription Factor 7-Like 2 Protein
beta Catenin
1103 Clinical Sciences
1114 Paediatrics And Reproductive Medicine
1117 Public Health And Health Services
Publication Status: Published
Appears in Collections:Department of Medicine
Faculty of Medicine



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