REGULATION OF ERCC-1 MRNA EXPRESSION BY INSULIN

工作总结：DNA修复酶的表达，包括ERCC-1， 可能受到荷尔蒙和生长因子刺激的控制。在……里面 本研究观察到，胰岛素增加了ERCC-1的mRNA水平 在中国仓鼠卵巢细胞中高表达人胰岛素受体 (HIRc细胞)和完全分化的3T3-L1脂肪细胞。至 探讨ERCC-1基因上调的机制 在HIRc细胞中的表达，已知的各种药理工具 抑制使用了不同的信号通路。这些抑制剂都不是 影响未刺激细胞中ERCC-1mRNA的表达。这个 两种化学上不相关的磷脂酰肌醇对细胞的预处理 3‘-激酶抑制剂Wortmannin和LY294002未能阻断2倍 胰岛素可增加ERCC-1mRNA的表达。同样，对pp70 S6的抑制 雷帕霉素的激活剂对这种胰岛素反应没有明显影响。在……里面 相反，改变p21ras依赖的通路，无论是甘露霉素还是 RAS法尼化的抑制剂，或PD98059，一种 丝裂原活化蛋白激酶/细胞外反应激酶 抑制胰岛素对ERCC-1mRNA的诱导作用(P&lt；0.001)。 此外，对RNA和蛋白质合成的抑制是负调控的 该胰岛素调节基因的表达(P&lt；0.005)。这些结果 提示胰岛素通过激活细胞外信号转导通路增强ERCC-1mRNA水平 不涉及磷脂酰肌醇的Ras-ERK依赖通路 3‘-激酶/pp70 S6激酶。 荷尔蒙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的极大兴趣。高血糖 糖尿病条件下发现的浓度会导致DNA损伤 与DNA修复扰动相关的多种细胞类型 综合。DNA修复的这种损伤可能导致基因异常 表达导致包括糖尿病在内的退行性疾病 微血管病。目前正在努力评估DNA的表达是否 在糖尿病情况下，修复基因会发生变化。

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.