Structural Analysis of Candidate Genes for type 2 Diabetes

一个基因被认为是Pimas 2型糖尿病的候选基因，如果1）它与另一个人群中的糖尿病表型相关，或2）它具有生理相关功能，并位于与糖尿病相关的染色体区域。迄今为止已分析的候选基因包括那些在其他人群中与Mody相关的基因。 我们在HNFla、HNFlb和HNF 3b基因中发现了几种多态性，但没有一种与Pimas的早发性糖尿病相关。 然而，HNFlb中的一种多态性预测了蛋白质的DNA结合区域内的非保守氨基酸取代。因此，研究了HNF 1b中的取代的功能变异性。我们已经将HNF 1b的两种多态性形式克隆到表达载体中。此外，我们已经克隆了大鼠白蛋白启动子，这是由HNF 1b调控，到荧光素酶报告质粒。将含有HNF 1b的每个载体与荧光素酶报告质粒共转染到Cos 7细胞中。我们已经发现，不常见的氨基酸变异上调转录从大鼠白蛋白promoter.We还分析了多态性（UCSNP-43）的钙蛋白酶10基因被认为是负责糖尿病位点NIDDM 1在墨西哥裔美国人。我们对1300名皮马印第安人的这种多态性进行了基因分型，并发现UCSNP-43与非糖尿病皮马人的胰岛素抵抗和营养分配之间存在关联。在墨西哥裔美国人和两个欧洲人群中，由3个多态性组成的特定单倍型为糖尿病的发展提供了风险单倍型。因此，我们对1300只Pimas的钙蛋白酶10基因的两个额外多态性进行了基因分型。然而，这种单倍型并没有增加皮马人患糖尿病的风险。我们还对15号染色体上不同的钙蛋白酶基因附近的另一种多态性进行了基因分型，该基因被认为与墨西哥裔美国人的钙蛋白酶10位点相互作用。我们没有发现任何显着的协会与15号染色体上的多态性在Pimas。

A gene is considered a candidate gene for type 2 diabetes in Pimas if 1) it is associated with a diabetic phenotype in another population or 2) it has a physiologically relevant function and is positioned in a chromosomal region that is linked to diabetes. Candidate genes which have been analyzed to date include those genes which are associated with Mody in other populations. We identified several polymorphisms in the HNFla, HNFlb, and HNF3b genes, but none were associated with early onset diabetes in Pimas. One polymorphism in HNFlb, however, predicts a non-conservative amino acid substitution within the DNA binding region of the protein. Therefore the substitution in HNF1b was investigated for functional variability. We have cloned the two polymorphic forms of HNF1b into expression vectors. In addition, we have cloned the rat albumin promoter, which is regulated by HNF1b, into a luciferase reporter plasmid. Each of the vectors containing HNF1b were co-transfected with the luciferase reporter plasmid into Cos 7 cells. We have found that the uncommon amino acid variant upregulates transcription from the rat albumin promoter.We have also analyzed a polymorphism (UCSNP-43)in the calpain 10 gene which is thought to be responsible for the diabetic locus NIDDM1 in Mexican Americans. We have genotyped this polymophism in 1300 Pima Indians and have found an association between UCSNP-43 and insulin resistance and nutrient partitioning in non-diabetic Pimas. In Mexican Americans and two European populations, a specific haplotype consisting of 3 polymorphisms provided an at risk haplotype for the development of diabetes. Therefore we genotyped two additional polymorphisms in the calpain 10 gene in 1300 Pimas. This haplotype, however, did not confer an increased risk of diabetes in the Pima population. We have also genotyped another polymorphism near a different calpain gene on chromosome 15 which is thought to interact with the calpain 10 locus in Mexican Americans. We did not find any significant associations with the polymorphism on chromosome 15 in Pimas.