School of Life Sciences, Tsinghua University, Beijing 100084, P.R. China.
Mol Med Rep. 2012 Dec;6(6):1379-84. doi: 10.3892/mmr.2012.1113. Epub 2012 Oct 1.
Zinc finger and BTB domain-containing 7A (Zbtb7A) is a proto-oncogene overexpressed in numerous cancers. In this study, we explored the mechanism of insulin-induced Zbtb7A expression. Real-time PCR and western blotting were used to detect Zbtb7A expression. Zbtb7A promoter activity was monitored by Luciferase reporter assay. It was shown that insulin elevates the mRNA and protein levels of the Zbtb7A gene in HepG2 cells. Using chemical inhibitors of insulin downstream pathways, we demonstrated that the insulin-induced Zbtb7A gene expression was completely blocked by LY294002, a PI3K/AKT inhibitor, and partially attenuated by the MAPK inhibitor PD98059. Transfection of HepG2 cells with a 1 kb Zbtb7A promoter-luciferase reporter construct revealed a dose-dependent activation of the Zbtb7A promoter by insulin, while mutation of the Sp1 binding site within the Zbtb7A promoter resulted in the failure of insulin-induced promoter activation, suggesting that insulin increases Zbtb7A expression through transcriptional regulation mediated by Sp1 in HepG2 cells.
锌指和 BTB 结构域蛋白 7A（Zbtb7A）是一种在许多癌症中过度表达的原癌基因。在这项研究中，我们探索了胰岛素诱导 Zbtb7A 表达的机制。实时 PCR 和 Western blot 用于检测 Zbtb7A 的表达。通过荧光素酶报告基因检测 Zbtb7A 启动子活性。结果表明，胰岛素可提高 HepG2 细胞中 Zbtb7A 基因的 mRNA 和蛋白水平。使用胰岛素下游途径的化学抑制剂，我们证明胰岛素诱导的 Zbtb7A 基因表达被 PI3K/AKT 抑制剂 LY294002 完全阻断，而 MAPK 抑制剂 PD98059 部分减弱。用 1kb 的 Zbtb7A 启动子-荧光素酶报告基因转染 HepG2 细胞，发现胰岛素可剂量依赖性地激活 Zbtb7A 启动子，而 Zbtb7A 启动子中 Sp1 结合位点的突变导致胰岛素诱导的启动子激活失败，表明胰岛素通过 Sp1 在 HepG2 细胞中介导的转录调控增加 Zbtb7A 的表达。
