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。这一目标将通过遵循肝脏中大鼠雄激素受体（rAR）基因的年龄依赖性调节范式来实现。从年轻成年（3个月大）到衰老（24个月大）大鼠，rAR基因的肝脏表达下降超过70倍。在之前的资助期间，我们已经描述了rAR基因启动子的特征，并确定了一些可能有助于其年龄依赖性调控的调控元件。这些包括：1)一种新型的正作用反式激活因子，称为年龄依赖性因子（ADF），其肝脏水平在老年期间下降5- 7倍；2)核因子κ B （nf - κ B）是rAR基因的负调节因子，在肝脏中经历明显的年龄依赖性增加；3)一种新的单链嘧啶结合因子（ssPyrBF），在老年大鼠肝脏中增加约两倍，并可能干扰Sp1在rAR启动子的同嘌呤/同嘧啶区域的结合；4)涉及dna弯曲蛋白（称为雄激素受体抑制因子，ARRF）和核因子-1 （NF-1）的负复合调控元件，其组分亚型的表达随年龄而变化。本次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的克隆与鉴定；3)阐明NF-1与ARRF相互作用下调rAR基因的机制基础；4) CCAAT/增强子结合蛋白（C/EBP）在rAR基因调控中的潜在作用及其通过异源二聚化与NF-kappa B的功能相互作用的研究。由于这些转录因子在rAR基因的年龄依赖性调控中的重要影响，以及C/EBP-NF-kappa B系统在氧化应激和炎症的整体管理中的良好作用，这些研究结果有望为研究衰老背景下雄激素受体基因调控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.