A novel type 2 diabetes risk allele increases the promoter activity of the muscle-specific small ankyrin 1 gene

Rengna Yan,Shanshan Lai,Vincenzo Sorrentino,Hong Du,Hongfei Shi,Zhenming Cai,Huimei Chen,Yang Yang

doi:10.1038/srep25105

Abstract

Genome-wide association studies have identified Ankyrin-1 (ANK1) as a common type 2 diabetes (T2D) susceptibility locus. However, the underlying causal variants and functional mechanisms remain unknown. We screened for 8 tag single nucleotide polymorphisms (SNPs) in ANK1 between 2 case-control studies. Genotype analysis revealed significant associations of 3 SNPs, rs508419 (first identified here), rs515071, and rs516946 with T2D (P < 0.001). These SNPs were in linkage disequilibrium (r2 > 0.80); subsequent analysis indicated that the CCC haplotype associated with increased T2D susceptibility (OR 1.447, P < 0.001). Further mapping showed that rs508419 resides in the muscle-specific ANK1 gene promoter. Allele-specific mRNA and protein level measurements confirmed association of the C allele with increased small ANK1 (sAnk1) expression in human skeletal muscle (P = 0.018 and P < 0.001, respectively). Luciferase assays showed increased rs508419-C allele transcriptional activity in murine skeletal muscle C2C12 myoblasts, and electrophoretic mobility-shift assays demonstrated altered rs508419 DNA-protein complex formation. Glucose uptake was decreased with excess sAnk1 expression upon insulin stimulation. Thus, the ANK1 rs508419-C T2D-risk allele alters DNA-protein complex binding leading to increased promoter activity and sAnk1 expression; thus, increased sAnk1 expression in skeletal muscle might contribute to T2D susceptibility.

Highlights

Genome-wide association studies have identified Ankyrin-1 (ANK1) as a common type 2 diabetes (T2D) susceptibility locus
The analysis of genome wide association studies (GWAS) data showed a significant association between Type 2 diabetes (T2D) and single nucleotide polymorphisms (SNPs) in Ankyrin 1 (ANK1), rs515071, and rs516946, and the importance of extended analyses was confirmed in multi-ethnic groups[14,15]
Analysis in stage 1 showed that rs508419 (P = 4.830 × 10−4), rs515071 (P = 3.630 × 10−4), and rs516946 (P = 1.410 × 10−4) of ANK1 were significantly associated with T2D (Table 2)

Summary

Introduction

Genome-wide association studies have identified Ankyrin-1 (ANK1) as a common type 2 diabetes (T2D) susceptibility locus. The analysis of GWAS data showed a significant association between T2D and SNPs in ANK1, rs515071, and rs516946, and the importance of extended analyses was confirmed in multi-ethnic groups[14,15]. The association of these variations with T2D was independent of associations related to the HbA1c levels. We identified candidate T2D risk SNPs in the ANK1 locus and examined their functional effects on the expression of ANK1 and its isoforms in skeletal muscles, as well as on glucose uptake in vitro. We suggest that the results of these analyses might explain the previous GWAS-based identification of T2D-associated variants in this region

Methods

Results

Conclusion