Lucas P C, O'Brien R M, Mitchell J A, Davis C M, Imai E, Forman B M, Samuels H H, Granner D K
Department of Molecular Physiology and Biophysics, Vanderbilt University Medical School, Nashville, TN 37232-0615.
Proc Natl Acad Sci U S A. 1991 Mar 15;88(6):2184-8. doi: 10.1073/pnas.88.6.2184.
Several hormones, including insulin, glucagon, and glucocorticoids, regulate the expression of the rate-limiting gluconeogenic enzyme, phosphoenolpyruvate carboxykinase [GTP: oxaloacetate carboxy-lyase (transphosphorylating); EC 4.1.1.32; PEPCK] in liver. In this report we demonstrate that retinoic acid (RA) also regulates PEPCK expression by inducing a 3-fold increase in the rate of transcription of the PEPCK gene. A RA response element located between -468 and -431 in the PEPCK promoter mediates a 7-fold increase in expression of a chimeric construct containing the basal PEPCK promoter ligated to the chloramphenicol acetyltransferase reporter gene. This element confers RA responsiveness through the heterologous thymidine kinase promoter and functions relatively independent of position and orientation. An 18-base-pair core sequence (-451 to -434) (i) mediates an effect of RA on PEPCK gene expression and contains motifs found in two other RA response elements; (ii) corresponds to AF1, an accessory factor element that is an integral component of the complex glucocorticoid response unit in the PEPCK gene promoter; (iii) is in a region involved in the developmental expression of the PEPCK gene; and (iv) shows homology to elements involved in the tissue-specific regulation of genes, including the hepatic apolipoprotein genes and the alpha 1-antitrypsin gene.
包括胰岛素、胰高血糖素和糖皮质激素在内的多种激素,可调节肝脏中限速糖异生酶磷酸烯醇式丙酮酸羧激酶[GTP:草酰乙酸羧化裂解酶(转磷酸化);EC 4.1.1.32;PEPCK]的表达。在本报告中,我们证明视黄酸(RA)也可通过使PEPCK基因转录速率提高3倍来调节PEPCK的表达。位于PEPCK启动子中-468至-431之间的RA反应元件介导了包含与氯霉素乙酰转移酶报告基因连接的基础PEPCK启动子的嵌合构建体的表达增加7倍。该元件通过异源胸苷激酶启动子赋予RA反应性,并且其功能相对独立于位置和方向。一个18个碱基对的核心序列(-451至-434):(i)介导RA对PEPCK基因表达的作用,并且包含在其他两个RA反应元件中发现的基序;(ii)对应于AF1,一种辅助因子元件,是PEPCK基因启动子中复合糖皮质激素反应单元的组成部分;(iii)位于参与PEPCK基因发育表达的区域;(iv)与参与基因组织特异性调节的元件具有同源性,包括肝脏载脂蛋白基因和α1-抗胰蛋白酶基因。