Aging and Androgen Gene Regulation

这个项目的目标是探索控制生殖过程和衰老的重叠调节程序。这一目标将追求以下的范例，大鼠雄激素受体（rAR）基因在肝脏中的年龄依赖性调节。rAR基因的肝脏表达从成年（3月龄）到衰老（24月龄）大鼠下降超过70倍。在上一个资助期间，我们对rAR基因启动子进行了表征，并确定了一些可能有助于其年龄依赖性调控的调控元件。其中包括：1）一种新的积极作用的反式激活因子，称为年龄依赖因子（ADF），其肝脏水平在老年期间下降5至7倍; 2）核因子κ B（NF-κ B），rAR基因的负调节因子，其在肝脏中经历显著的年龄依赖性增加; 3）一种新的单链嘧啶结合因子（ssPyrBF），其在老年大鼠的肝脏中显示出约两倍的增加，并且可以潜在地干扰Sp1在同型嘌呤/rAR启动子的同嘧啶区;和4）涉及DNA弯曲蛋白（称为雄激素受体阻遏因子，ARRF）和核因子-1（NF-1）的负复合调节元件，其在其组分同种型的表达中显示年龄依赖性改变。本更新申请的具体目的包括：1）ADF和ssPyrBF的纯化和表征; 2）ADF和ssPyrBF cDNA的克隆和表征; 3）阐明NF-1和ARRF相互作用在rAR基因下调中的机制基础;和4）检查CCAAT/增强子结合蛋白（C/EBP）在rAR基因调节中的潜在作用，并研究其与NF-κ B的功能相互作用。κ B通过异源二聚化。由于这些转录因子在rAR基因的年龄依赖性调节中的重要影响以及C/EBP-NF-κ B系统在氧化应激和炎症的整体管理中的充分记录的作用，这些研究的结果有望为衰老背景下雄激素受体基因调节的分子基础提供新的见解。

The goal of this project is to explore the overlapping regulatory programs that control both the reproductive process and aging. This goal will be pursued by following the paradigm of the age-dependent regulation of the rat androgen receptor (rAR) gene in the liver. The hepatic expression of the rAR gene declines more than 70-fold from young-adult (3-month old) to senescent (24-month old) rats. During the previous funding period, we have characterized the rAR gene promoter and identified a number of regulatory elements that can potentially contribute to its age-dependent regulation. These include: 1) A novel positively acting trans-activator called the age-dependent factor (ADF) whose hepatic level declines by 5-to 7-fold during old age; 2) The nuclear factor kappa B (NF-kappa B), a negative regulator of the rAR gene, that undergoes a marked age-dependent increase in the liver; 3) A novel single-strand pyrimidine binding factor (ssPyrBF) which shows about a two-fold increase in the liver of old rats and can potentially interfere with the binding of Sp1 at the homopurine/homopyrimidine region of the rAR promoter; and 4) A negative composite regulatory element involving a DNA-bending protein (designated as androgen receptor repressor factor, ARRF) and the nuclear factor-1 (NF-1) which shows age- dependent alterations in the expression of its component isoforms. The specific aims of this renewal application include: 1) Purification and characterization of ADF and ssPyrBF; 2) Cloning and characterization of the ADF and ssPyrBF cDNAs; 3) Elucidation of the mechanistic basis of NF-1 and ARRF interaction in the down-regulation of the rAR gene; and 4) Examination of the potential role of the CCAAT/enhancer binding protein (C/EBP) in the regulation of the rAR gene and investigation of its functional interaction with NF-kappa B through heterodimerization. Because of the important influence of these transcription factors in the age-dependent regulation of the rAR gene and the well-documented role of C/EBP-NF-kappa B system in the overall management of oxidative stress and inflammation, results of these studies are expected to provide new insights into the molecular basis of the androgen receptor gene regulation in the context of aging.