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目的利用人肝癌细胞株(HepG2)探讨糖皮质激素和胰岛素对丙酮酸脱氢酶激酶4(PDK-4)在转录水平的相应作用。方法首先通过标准的分子生物学技术制备PDK-4的5‘启动子基因,而后利用荧光酶素方法在HePG2细胞株中,通过时间依赖探讨糖皮质激素和胰岛素对PDK-4在转录水平上表达的影响。结果人工合成的糖皮质激素地塞米松能有效的增加PDK-4基因在转录水平表达。相反,胰岛素单独使用作用很小,但可明显降低糖皮质激素的正面促进作用。结论糖皮质激素抑制丙酮酸脱氢酶复合物(PDC)的作用至少部分上是通过诱导PDK-4的表达而使丙酮酸向草酰乙酸转化(糖异生途径)。通过对抗糖皮质激素诱导的PDK-4的表达,胰岛素能够起到相反的作用。研究开发PDK-4的拮抗剂可对难治性血糖异常问题及脂代谢异常疾病的治疗开辟一条新的途径。
Objective To investigate the effects of glucocorticoid and insulin on the transcriptional level of pyruvate dehydrogenase kinase 4 (PDK-4) using human hepatoma cell line HepG2. Methods Firstly, the 5 ’promoter of PDK-4 gene was prepared by standard molecular biology techniques. Then, the expression of PDK-4 at transcriptional level by glucocorticoid and insulin in HePG2 cell line was determined by time-dependent luciferase assay Impact. Results The synthetic glucocorticoid dexamethasone can effectively increase the expression of PDK-4 gene at the transcriptional level. In contrast, insulin alone has little effect, but significantly reduces the positive effects of glucocorticoids. Conclusions Glucocorticoid inhibition of the role of the pyruvate dehydrogenase complex (PDC) at least partially converts pyruvate to oxaloacetate (gluconeogenic pathway) by inducing PDK-4 expression. Insulin can have the opposite effect by counteracting glucocorticoid-induced PDK-4 expression. Research and development of PDK-4 antagonists can open up a new way for the treatment of refractory dysglycemia and lipid metabolism disorders.