REGULATION OF ERCC-1 MRNA EXPRESSION BY INSULIN

工作总结：DNA修复酶的表达，包括ERCC-1， 可能受激素和生长因子刺激的控制。 在 这项研究观察到，胰岛素增加ERCC-1 mRNA水平， 在过度表达人胰岛素受体的中国仓鼠卵巢细胞中 (HIRc细胞）和完全分化的3 T3-L1脂肪细胞中。 到 研究ERCC-1基因表达增加的机制 在HIRc细胞中的表达，各种已知的药理学工具， 抑制不同的信号通路。 这些抑制剂 影响未受刺激细胞中ERCC-1 mRNA的量。 的 用两种化学上不相关的磷脂酰肌醇预处理细胞 3 '-激酶抑制剂wortmannin和LY 294002不能阻断2倍的 胰岛素增加ERCC-1 mRNA。 同样，抑制pp 70 S6 雷帕霉素激酶对这种胰岛素应答没有明显影响。 在 相反，用manumycin， Ras法尼基化的抑制剂，或PD 98059， 丝裂原活化蛋白激酶/细胞外反应激酶 激酶抑制胰岛素对ERCC-1 mRNA的诱导作用（P<0.001）。 此外，RNA和蛋白质合成的抑制负调节 胰岛素调节基因的表达量明显增加（P<0.005）。 这些结果 提示胰岛素通过激活ERCC-1 mRNA水平， 不涉及磷脂酰肌醇的Ras-ERK依赖性通路 3 '-激酶/pp 70 S6激酶。 激素和生长因子可以控制 哺乳动物细胞中的DNA修复基因引起了人们极大的兴趣。 高糖 在糖尿病条件下发现的浓度导致DNA损伤， 与DNA修复扰动相关的多种细胞类型 合成.这种DNA修复的损伤可能导致异常的基因表达。 导致退行性疾病的表达，包括糖尿病 微血管病 目前正在努力评估DNA表达是否 修复基因在糖尿病条件下发生改变。

Summary of work: Expression of DNA repair enzymes, which includes ERCC-1, may be under the control of hormonal and growth factor stimulation. In this study, it was observed that insulin increased ERCC-1 mRNA levels both in Chinese hamster ovary cells overexpressing human insulin receptors (HIRc cells) and in fully differentiated 3T3-L1 adipocytes. To investigate the mechanisms underlying the increase in ERCC-1 gene expression in HIRc cells, a variety of pharmacological tools known to inhibit distinct signaling pathways were used. None of these inhibitors affected the amount of ERCC-1 mRNA in unstimulated cells. The pretreatment of cells with two chemically unrelated phosphatidylinositol 3'-kinase inhibitors, wortmannin and LY294002, failed to block the 2-fold increase in ERCC-1 mRNA by insulin. Likewise, inhibition of pp70 S6 kinase by rapamycin had no apparent effects on this insulin response. In contrast, altering p21ras-dependent pathway with either manumycin, an inhibitor of Ras farnesylation, or PD98059, an inhibitor of the mitogen-activated protein kinase/extracellular-response kinase (ERK) kinase, suppressed the induction of ERCC-1 mRNA by insulin (P<0.001). Furthermore, inhibition of RNA and protein synthesis negatively regulated the expression of this insulin-regulated gene (P<0.005). These results suggest that insulin enhances ERCC-1 mRNA levels by activation of the Ras-ERK-dependent pathway without involvement of the phosphatidylinositol 3'-kinase/pp70 S6 kinase. The notion that hormones and growth factors could control expression of DNA repair genes in mammalian cells is of great interest. High glucose concentrations found in diabetic conditions results in DNA damage in a variety of cell types associated with perturbation of DNA repair synthesis. Such impairment in DNA repair may result in aberrant gene expression leading to degenerative disorders which includes diabetic microangiopathy. Efforts are underway to assess whether expression of DNA repair genes is altered in diabetic conditions.