Department of Cell Physiology and Metabolism, University of Geneva, Geneva, Switzerland.
PLoS One. 2010 Jun 10;5(6):e11053. doi: 10.1371/journal.pone.0011053.
Genome-wide association studies have identified susceptibility genes for development of type 2 diabetes. We aimed to examine whether a subset of these (comprising FTO, IDE, KCNJ11, PPARG and TCF7L2) were transcriptionally restricted to or enriched in human beta cells by sorting islet cells into alpha and beta - specific fractions. We also aimed to correlate expression of these transcripts in both alpha and beta cell types with phenotypic traits of the islet donors and to compare diabetic and non-diabetic cells.
METHODOLOGY/PRINCIPAL FINDINGS: Islet cells were sorted using a previously published method and RNA was extracted, reverse transcribed and used as the template for quantitative PCR. Sorted cells were also analysed for insulin and glucagon immunostaining and insulin secretion from the beta cells as well as insulin, glucagon and GLP-1 content. All five genes were expressed in both alpha and beta cells, with significant enrichment of KCNJ11 in the beta cells and of TCF7L2 in the alpha cells. The ratio of KCNJ11 in beta to alpha cells was negatively correlated with BMI, while KCNJ11 expression in alpha cells was negatively correlated with age but not associated with BMI. Beta cell expression of glucagon, TCF7L2 and IDE was increased in cells from islets that had spent more time in culture prior to cell sorting. In beta cells, KCNJ11, FTO and insulin were positively correlated with each other. Diabetic alpha and beta cells had decreased expression of insulin, glucagon and FTO.
CONCLUSIONS/SIGNIFICANCE: This study has identified novel patterns of expression of type 2 diabetes susceptibility genes within sorted islet cells and suggested interactions of gene expression with age or BMI of the islet donors. However, expression of these genes in islets is less associated with BMI than has been found for other tissues.
全基因组关联研究已经确定了 2 型糖尿病发病的易感基因。我们旨在通过将胰岛细胞分为α和β特异亚群来检测这些基因（包括 FTO、IDE、KCNJ11、PPARG 和 TCF7L2）是否在转录水平上局限于或富集于人类β细胞。我们还旨在将这些转录本在α和β细胞类型中的表达与胰岛供体的表型特征相关联，并比较糖尿病和非糖尿病细胞。
方法/主要发现：使用先前发表的方法对胰岛细胞进行分选，提取 RNA，反转录并作为定量 PCR 的模板。还分析了分选细胞的胰岛素和胰高血糖素免疫染色以及β细胞的胰岛素分泌以及胰岛素、胰高血糖素和 GLP-1 含量。这五个基因在α和β细胞中均有表达，KCNJ11 在β细胞中显著富集，TCF7L2 在α细胞中显著富集。β细胞中 KCNJ11 与α细胞的比值与 BMI 呈负相关，而α细胞中 KCNJ11 的表达与年龄呈负相关，但与 BMI 无关。在细胞分选前在培养中花费更多时间的胰岛中，β细胞中胰高血糖素、TCF7L2 和 IDE 的表达增加。在β细胞中，KCNJ11、FTO 和胰岛素彼此之间呈正相关。糖尿病的α和β细胞中胰岛素、胰高血糖素和 FTO 的表达减少。
结论/意义：本研究在分选的胰岛细胞中确定了 2 型糖尿病易感性基因表达的新模式，并提示基因表达与胰岛供体的年龄或 BMI 之间存在相互作用。然而，这些基因在胰岛中的表达与 BMI 的相关性不如在其他组织中发现的那么大。
