Ryu Jihye, Lee Chaeyoung
School of Systems Biomedical Science, Soongsil University, Seoul, Korea.
J Diabetes. 2016 Mar;8(2):253-9. doi: 10.1111/1753-0407.12289. Epub 2015 Jun 9.
Functional knowledge of most genetic variants identified from genome-wide association studies (GWAS) for type 2 diabetes (T2D) is limited. A recent T2D GWAS revealed an association signal (rs4689388) upstream of the gene encoding Wolfram syndrome 1 (WFS1) whose intrinsic nucleotide variants had been previously associated with T2D in several candidate gene analyses. The aim of the present study was to identify functional variants of the GWAS signal.
Promoter activity of luciferase reporter constructs was compared with haplotypes including variants composing a linkage disequilibrium block in the vicinity of rs4689388 in HEK293 and HepG2 cells.
Promoter activity was highest with the most frequent haplotype (H1; ATCGT) and lowest with second most frequent haplotype (H2; GATCG), whose nucleotide alleles were all complementary to those of H1. Further analysis with artificial haplotypes revealed differential transcriptional activity by nucleotide substitution of rs4320200, rs13107806, or rs13127445 (P < 0.05). This concurred with changes in predicted transcription factor binding site by their allele substitutions.
The previously reported GWAS signal for T2D may be identified by the differential promoter activity of rs4320200, rs13107806, and rs13127445 in the promoter of WFS1 by nucleotide substitution.
从全基因组关联研究（GWAS）中鉴定出的大多数2型糖尿病（T2D）基因变异的功能知识有限。最近一项T2D的GWAS研究揭示了编码Wolfram综合征1（WFS1）基因上游的一个关联信号（rs4689388），其内在核苷酸变异在之前的几个候选基因分析中已与T2D相关。本研究的目的是鉴定该GWAS信号的功能变异。
在HEK293和HepG2细胞中，将荧光素酶报告基因构建体的启动子活性与包含rs4689388附近构成连锁不平衡块的变异的单倍型进行比较。
最常见单倍型（H1；ATCGT）的启动子活性最高，第二常见单倍型（H2；GATCG）的启动子活性最低，其核苷酸等位基因均与H1互补。用人造单倍型进行的进一步分析显示，rs4320200、rs13107806或rs13127445的核苷酸替换导致转录活性存在差异（P < 0.05）。这与它们的等位基因替换导致的预测转录因子结合位点变化一致。
先前报道的T2D的GWAS信号可能是由rs4320200、rs13107806和rs13127在WFS1启动子中的核苷酸替换导致的启动子活性差异所确定。
