CHARACTERIZATION OF TYPE 2 DIABETES SUSCEPTIBILITY ALLELES AT THE PKLR LOCUS

本子项目是利用由NIH/NCRR资助的中心赠款提供的资源的众多研究子项目之一。子项目和研究者（PI）可能已经从另一个NIH来源获得了主要资金，因此可以在其他CRISP条目中表示。列出的机构是中心的，不一定是研究者的机构。大量证据支持在染色体1q21-q23上存在几个2型糖尿病（T2DM）易感基因。肝丙酮酸激酶基因（PKLR）附近的变异与T2DM的关联已经在几个高加索人群中被复制，但关联区域很广，至少包括6个表达基因。这一提议将验证该区域的非编码变异改变一个或多个基因的表达，并导致携带易感单倍型个体的肝糖产量增加的假设。提出了一种多方面的方法，首先使用单核苷酸多态性定义高加索人和非裔美国人受试者的关联区域（目的1）。在该区域内，将筛选24名白种人和24名非洲裔美国人的所有编码、保守和推定调控区域的变异。将寻找重复和重排改变基因拷贝数的证据（目标2）。目标3将测试该区域在皮下脂肪、肌肉和永生化淋巴细胞中所有可调节基因的基因型表达水平差异，并将测试在转录序列中发现常见变异的等位基因表达差异。目的4将测试每个单倍型的10个纯合个体，以确定胰岛素分泌、胰岛素敏感性和肝脏葡萄糖产量。脂肪和肌肉将获得表型与该区域基因的表达谱相关。这些研究可以确定导致T2DM的特定核苷酸变异，或者可以确定增加该区域易感性的途径和基因。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Considerable evidence supports the existence of several susceptibility genes for type 2 diabetes (T2DM) on chromosome 1q21-q23. Association of variants near the liver pyruvate kinase gene (PKLR) with T2DM has been replicated in several Caucasian populations, but the region of association is broad and includes at least 6 expressed genes. This proposal will test the hypothesis that noncoding variants in this region alter expression of one or more genes and result in increased hepatic glucose production among individuals carrying the susceptible haplotype. A multifaceted approach is proposed, that will first define the region of association in both Caucasian and African American subjects using single nucleotide polymorphisms (Aim 1). Within this region, variation in all coding, conserved, and putative regulatory regions will be screened for variation in 24 Caucasian and 24 African American individuals. Evidence for duplications and rearrangements altering gene copy number will be sought (Aim 2). Aim 3 will test for differences in expression levels by genotype for all amenable genes in this region in subcutaneous fat, muscle, and immortalized lymphocytes, and will test for differences in allelic expression where common variants in transcribed sequences are found. Aim 4 will test 10 individuals homozygous for each haplotype to determine insulin secretion, insulin sensitivity by euglycemic clamp, and hepatic glucose production. Fat and muscle will be obtained to correlate phenotype with expression profiles of genes in this region. These studies may identify the specific nucleotide variant leading to T2DM, or alternatively will identify the pathway and genes that increase susceptibility in this region.