摘要
目的 通过观察抗高血糖药物二甲双胍对肝糖异生中的关键限速酶磷酸烯醇丙酮酸羧激酶 (PEPCK)基因表达的调节以及胰岛素信号转导抑制剂的影响 ,探讨二甲双胍在肝细胞中作用的分子机制。方法 培养的小鼠肝癌细胞系 (H4IIE)用 0 1mmol/L二甲双胍温育 16h ,并加用不同的调节因子 ,如胰岛素、环磷酸腺苷 (cAMP)、地塞米松、胰岛素信号转导抑制剂等。PEPCK的mRNA水平通过Northernblot分析。结果 治疗浓度 0 .1mmol/L二甲双胍显著降低了基础PEPCK的mRNA水平约 75 % (P <0 .0 1) ,对cAMP和地塞米松刺激的PEPCKmRNA表达 ,二甲双胍单独作用无显著性效果 ,但通过与胰岛素的联合作用可抑制cAMP和地塞米松刺激的PEPCK的基因表达。当培养液中加入 0 .1nmol/L低浓度胰岛素与二甲双胍共同温育时 ,cAMP和地塞米松引起的PEPCKmRNA表达显著降低了 94 % (P <0 .0 1)。胰岛素信号转导抑制剂如磷脂酰肌醇 3激酶 (PI3K)抑制剂渥蔓青霉素(wortmannin)和有丝分裂原激活蛋白激酶 (MAPK)抑制剂UO12 6对二甲双胍的作用无显著影响 ,但wortmannin显著阻止了胰岛素对PEPCK基因表达的调节作用。结论 二甲双胍可通过独立的非胰岛素信号转导途径或是与胰岛素的联合作用抑制PEPCK的基因表达 。
Objective To investigate the effect and mechanism of antihyperglycemic agent metformin on the gene expression of phosphoenolpyruvate carboxykinase (PEPCK)--a key enzyme within the regulation of gluconeogenesis in hepatocytes and to determine whether the effects of metformin on hepatocytes are transmitted throughout the known insulin signaling pathways. Methods Confluent H4IIE rat heptoma cells were cultured with metformin 0.1mmol/L for 16 h and then stimulated with various agents: insulin, cyclic adenosine monophosphate(cAMP), dexamethasone, signaling transduction inhibitor wortmannin and UO126. The gene expression of PEPCK was examined by Northern blot analysis. Results Metformin significantly decreased basal PEPCK mRNA levels by 75 % ( P < 0.01). Incubation with metformin alone had no significant effect on cAMP /dexamethasone stimulated PEPCK gene expression. In contrast, insulin 0.1 nmol/L significantly inhibited cAMP /dexamethasone stimulated PEPCK gene expression by 67 % ( P < 0.01), when insulin 0.1 nmol/L was present together with metformin, cAMP/dexamethasone induced PEPCK gene expression was decreased by 94 % ( P < 0. 01). Both insulin signaling pathway inhibitors, phosphatidyl inositol 3 kinase (PI3K) inhibitor wortmannin and mitogen activated protein kinase (MAPK) inhibitor UO126, had no significant effect on inhibited PEPCK mRNA expression by metformin, but wortmannin blocked significantly inhibitory regulation of insulin on PEPCK gene expression ( P < 0.01). Conclusion Metformin can inhibit the PEPCK gene expression via either an insulin independent or interaction with insulin manner. The inhibitory effects of insulin on PEPCK gene expression are mediated through PI3K pathway, not MAPK pathway.
出处
《中华内科杂志》
CAS
CSCD
北大核心
2002年第10期663-666,共4页
Chinese Journal of Internal Medicine
