Comparative analysis of type 2 diabetes-associated SNP alleles identifies allele-specific DNA-binding proteins for the KCNQ1 locus

Although recent genome-wide association studies (GWAS) have been extremely successful, it remains a big challenge to functionally annotate disease-associated single nucleotide polymorphisms (SNPs), as the majority of these SNPs are located in non-coding regions of the genome. In this study, we described a novel strategy for identifying the proteins that bind to the SNP‑containing locus in an allele‑specific manner and successfully applied this method to SNPs in the type 2 diabetes mellitus susceptibility gene, potassium voltage-gated channel, KQT-like subfamily Q, member 1 (KCNQ1). DNA fragments encompassing SNPs, and risk or non-risk alleles were immobi- lized onto the novel nanobeads and DNA-binding proteins were purified from the nuclear extracts of pancreatic β cells using these DNA-immobilized nanobeads. Comparative analysis of the allele‑specific DNA ‑binding proteins indicated that the affinities of several proteins for the examined SNPs differed between the alleles. Nuclear transcription factor Y (NF-Y) specifically bound the non‑risk allele of the SNP rs2074196 region and stimulated the transcriptional activity of an artifi - cial promoter containing SNP rs2074196 in an allele‑specific manner. These results suggest that SNP rs2074196 modulates the affinity of the locus for NF‑Y and possibly induces subse - quent changes in gene expression. The findings of this study indicate that our comparative method using novel nanobeads is effective for the identification of allele‑specific DNA‑binding proteins, which may provide important clues for the functional impact of disease-associated non-coding SNPs.