Identification of type 2 diabetes mellitus susceptibility candidate genes in loci detected by QTL analysis of diabetic db mice,

我们先前定位了影响BKS、Cg-m+/+Lepr^&lt；db&gt；C3H或DBA2(D2)杂交F2群体T2D表型的四个主要数量性状基因座(QTL)。为了确定T2D的疾病易感基因，我们使用同基因小鼠绘制了该区域的图谱。我们的研究结果如下：1)我们通过供体(Db)小鼠与携带给定QTL基因组区域的D2品系受体小鼠的重复回交产生了同源小鼠，以测试每个QTL对糖尿病表型的影响。在4个QTL中，D2小鼠的两个区域的入渗与携带BKS等位基因的对照鼠显著不同。表型的差异在体重、脂肪垫重量、空腹血糖浓度和胰岛素水平(A区)；体重、脂肪垫重量和总胆固醇水平(B区)上重复。2)从BKS/D2同源区衍生出16个(A区)或22个(B区)同源亚系，用于两个QTL的精细定位。3)对一只同系小鼠的7个亚系进行分析，确定了影响A区体重、脂肪垫重量的3个Mb区域。对另一只同源基因小鼠的五个亚系的分析揭示了8Mb的区域，该区域影响B区的体重和脂肪垫重量。然而，我们无法绘制出与A区空腹血糖浓度相关的区域。这些同源亚系为精细定位表型指定的QTL区域提供了有力的工具。为了确定靶基因、mRNA和蛋白在亚基因小鼠和对照小鼠不同组织中的表达情况，我们实验室正在进行这一研究。

We previously mapped four major quantitative trait loci (QTLs) for type 2 diabetes mellitus (T2D), which affect T2D phenotypes in F_2 populations generated from a BKS.Cg-m+ /+ Lepr^<db> and C3H or DBA2 (D2) intercross. To identify the disease-susceptibility genes of T2D, we mapped the region using congenic mice. Our findings are as follows ; 1) We generated congenic mice by repeated backcross of donor (db) mice to recipient mice of D2 strain carrying a given QTL-containing genome region to test the effect of each QTL on diabetic phenotypes. Out of four QTLs, introgression of two regions of D2 mice was significantly different from that of control mice carrying BKS alleles. Differences in phenotypes were replicated in body weight, fat pad weight, fasting BG concentrations, and insulin level (A region) ; body weight, fat pad weight, and total cholesterol level (B region). 2) We generated 16 (for A region) or 22 (for B region) congenic sub-lines derived from BKS/D2 congenic region for two QTLs to facilitate fine mapping. 3) Analyses of seven sub-lines in one congenic mouse identified the region of three Mb, which affects body weight, fat pad weight in A region. Analyses of five sub-lines in another congenic mouse revealed the region of eight Mb, which affects body weight and fat pad weight in B region. However, we could not map the region correlating fasting BG concentrations in A region. These congenic sub-lines offered a powerful tool for fine mapping phenotypes-assigned QTL region. To identify the target gene, mRNA and protein expression analyses in various tissues from subcongenic and control mice are under way in our laboratory.