Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, 8415 MRB IV, 2213 Garland Avenue, Nashville, TN 37232-0615, USA.
Diabetologia. 2013 Jun;56(6):1306-16. doi: 10.1007/s00125-013-2875-3. Epub 2013 Mar 19.
AIMS/HYPOTHESIS: We previously identified the G6PC2 locus as a strong determinant of fasting plasma glucose (FPG) and showed that a common G6PC2 intronic single nucleotide polymorphism (SNP) (rs560887) and two common G6PC2 promoter SNPs (rs573225 and rs13431652) are highly associated with FPG. However, these promoter SNPs have complex effects on G6PC2 fusion gene expression, and our data suggested that only rs13431652 is a potentially causative SNP. Here we examine the effect of rs560887 on G6PC2 pre-mRNA splicing and the contribution of an additional common G6PC2 promoter SNP, rs2232316, to the association signal.
Minigene analyses were used to characterise the effect of rs560887 on G6PC2 pre-mRNA splicing. Fusion gene and gel retardation analyses characterised the effect of rs2232316 on G6PC2 promoter activity and transcription factor binding. The genetic association of rs2232316 with FPG variation was assessed using regression adjusted for age, sex and BMI in 4,220 Europeans with normal FPG.
The rs560887-G allele was shown to enhance G6PC2 pre-mRNA splicing, whereas the rs2232316-A allele enhanced G6PC2 transcription by promoting Foxa2 binding. Genetic analyses provide evidence for association of the rs2232316-A allele with increased FPG (β = 0.04 mmol/l; p = 4.3 × 10(-3)) as part of the same signal as rs560887, rs573225 and rs13431652.
CONCLUSIONS/INTERPRETATION: As with rs13431652, the in situ functional data with rs560887 and rs2232316 are in accord with the putative function of G6PC2 in pancreatic islets, and suggest that all three are potentially causative SNPs that contribute to the association between G6PC2 and FPG.
目的/假设：我们之前确定了 G6PC2 基因座是空腹血糖 (FPG) 的一个强有力的决定因素，并表明一个常见的 G6PC2 内含子单核苷酸多态性 (SNP) (rs560887) 和两个常见的 G6PC2 启动子 SNP(rs573225 和 rs13431652) 与 FPG 高度相关。然而，这些启动子 SNP 对 G6PC2 融合基因表达有复杂的影响，我们的数据表明，只有 rs13431652 是一个潜在的致病 SNP。在这里，我们研究了 rs560887 对 G6PC2 前体 mRNA 剪接的影响，以及另一个常见的 G6PC2 启动子 SNP(rs2232316) 对关联信号的贡献。
使用微基因分析来描述 rs560887 对 G6PC2 前体 mRNA 剪接的影响。融合基因和凝胶阻滞分析描述了 rs2232316 对 G6PC2 启动子活性和转录因子结合的影响。在 4220 名具有正常 FPG 的欧洲人中，使用回归分析评估了 rs2232316 与 FPG 变异的遗传关联，该回归分析调整了年龄、性别和 BMI。
结果表明，rs560887-G 等位基因增强了 G6PC2 前体 mRNA 的剪接，而 rs2232316-A 等位基因通过促进 Foxa2 结合增强了 G6PC2 的转录。遗传分析提供了证据，证明 rs2232316-A 等位基因与 FPG 升高有关（β=0.04mmol/l;p=4.3×10(-3))，这是与 rs560887、rs573225 和 rs13431652 相同的信号的一部分。
结论/解释：与 rs13431652 一样，rs560887 和 rs2232316 的原位功能数据与 G6PC2 在胰岛中的假定功能一致，这表明这三个 SNP 都可能是导致 G6PC2 与 FPG 相关的致病 SNP。
