Biological functions of ternary complex factors in pancreatic beta-cells

本研究旨在阐明三元复合因子(TCF)在转基因小鼠胰岛β细胞中的生物学功能。TCFs与血清反应因子相互作用，产生三元核蛋白复合体。TCFs是血清反应元件介导的转录的关键调节因子。Tcf蛋白也影响由转录因子AP-1介导的转录。ELK-1是转录因子TCF家族中的一员，在葡萄糖处理的胰岛β细胞中被激活，并与细胞生长和/或凋亡相关。我们已经建立了在胰岛β细胞中表达显性-阴性突变的Elk-1的条件转基因小鼠。该突变体干扰了所有TCF蛋白的DNA和SRF结合，从而损害了整个TCF家族的生物学功能。首先，对新产生的转基因小鼠的分析结果显示，Elk-1显性阴性突变体的β细胞特异性表达减少了胰岛β细胞中PDX-1和胰岛素的表达。本研究旨在阐明转基因表达对葡萄糖稳态、胰岛素释放、细胞增殖和细胞凋亡的影响。此外，将使用微阵列技术识别TCF靶基因。发现可能影响胰岛素生物合成和分泌、血糖稳态、β细胞增殖和细胞死亡的新的TCF调控候选基因，可能为研究糖尿病的发展开辟新的途径。

The research projects aims to elucidate the biological functions of ternary complex factors (TCF) in pancreatic beta-cells of transgenic mice. The TCFs interact with the serum-response factor, generating a ternary nucleoprotein complex. The TCFs are key regulators of serum-response element-mediated transcription. TCF proteins also influence transcription mediated by the transcription factor AP-1. Elk-1, a member of the TCF family of transcription factors, is activated in glucose-treated pancreatic beta-cells and has been correlated with cellular growth and/or apoptosis. We have generated conditional transgenic mice expressing dominant-negative mutant of Elk-1 in pancreatic beta-cells. The mutant interferes with DNA and SRF-binding of all TCF proteins and thus impairs the biological functions of the entire TCF family. First qRT-PCR-results obtained in the analysis of the newly generated transgenic mice revealed that beta-cell-specific expression of the dominant-negative mutant of Elk-1 reduced expression of Pdx-1 and insulin in pancreatic beta-cells. The investigation aims to elucidate the impact of transgene expression upon glucose homeostasis, insulin release, proliferation and apoptosis. In addition, TCF target genes will be identified using the microarray technology. The identification of new TCF-regulated candidate genes that may influence insulin biosynthesis and secretion, glucose homeostasis, beta-cell proliferation and cell death may open new routes to study the development of diabetes.