Wang Liangli, Li Yin, Hu Peng, Teng Christina T
Gene Regulation Section, Laboratory of Reproductive and Developmental Toxicology, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, NC 27709, USA.
Biochem J. 2008 Dec 15;416(3):407-19. doi: 10.1042/BJ20081085.
ERR (oestrogen-related receptor)-alpha modulates the oestrogen signalling pathway and regulates genes participating in the physiological energy balance programme. Oestrogen and PGC-1alpha (peroxisome proliferator-activated receptor-gamma coactivator-1alpha), the master regulator of the energy homoeostasis programme, both regulate the expression of ERRalpha through the MHRE (multi-hormone response element) of the ERRalpha gene. Although the molecular mechanism of oestrogen action on ERRalpha regulation is well characterized, the mechanism of PGC-1alpha induction is unclear. In this study, we examine chromatin structural changes and protein interactions at the MHRE nucleosome in response to PGC-1alpha expression in HK2 human kidney cells. We mapped the nucleosome positions of the ERRalpha gene promoter and examined the changes of histone acetylation in response to PGC-1alpha expression. The interactions of DNA-binding proteins, ERRalpha and ERRgamma, co-activators {CBP [CREB (cAMP-response-element-binding protein)-binding protein], p300, PCAF (p300/CBP-associated factor)}, co-repressor [RIP140 (receptor-interacting protein of 140 kDa)] and RNA polymerase II at the MHRE nucleosome region were investigated over time before and after PGC-1alpha expression in the HK2 cells. We found a dynamic cyclic interaction of these proteins shortly after PGC-1alpha expression and a slower cycling interaction, with fewer proteins involved, 20 h later. By using the siRNA (small interfering RNA) knockdown approach, we discovered that ERRgamma was involved in the initial phase, but not in the later phase, of PGC-1alpha-induced ERRalpha expression.
雌激素相关受体（ERR）-α调节雌激素信号通路，并调控参与生理能量平衡程序的基因。雌激素和能量稳态程序的主要调节因子过氧化物酶体增殖物激活受体γ共激活因子-1α（PGC-1α）均通过ERRα基因的多激素反应元件（MHRE）调节ERRα的表达。尽管雌激素对ERRα调节作用的分子机制已得到充分表征，但PGC-1α诱导的机制尚不清楚。在本研究中，我们检测了HK2人肾细胞中响应PGC-1α表达时，MHRE核小体处的染色质结构变化和蛋白质相互作用。我们绘制了ERRα基因启动子的核小体位置，并检测了响应PGC-1α表达时组蛋白乙酰化的变化。在HK2细胞中PGC-1α表达之前和之后，随时间研究了DNA结合蛋白ERRα和ERRγ、共激活因子[CBP（cAMP反应元件结合蛋白结合蛋白）、p300、PCAF（p300/CBP相关因子）]、共抑制因子[RIP140（140 kDa的受体相互作用蛋白）]和RNA聚合酶II在MHRE核小体区域的相互作用。我们发现，PGC-1α表达后不久，这些蛋白质存在动态循环相互作用，而20小时后相互作用循环变慢，涉及的蛋白质减少。通过使用小干扰RNA（siRNA）敲低方法，我们发现ERRγ参与PGC-1α诱导的ERRα表达的初始阶段，但不参与后期阶段。
