AGE & HORMONE-DEPENDENT REGULATION OF A HEPATIC PROTEIN

大鼠妊娠期肝雄激素受体mRNA的差异表达 成熟和衰老与雄激素反应性直接相关， 成年男性肝脏与青春期前雄激素不敏感 和衰老。 一种31 kDa的雄激素抑制性肝蛋白，命名为 SMP-2在哺乳动物的发育期以相对高的丰度表达。 与其极低表达水平相比，肝脏雄激素不敏感 雄激素敏感的成年男性。 核泄漏研究表明， 年龄依赖性的再激活和雄激素介导的SMP-2抑制， 主要通过改变基因转录速率来调节。 的 拟议的研究旨在审查以下问题： 1)鉴定推定的转录反式激活因子， 在成熟和衰老过程中的差异表达/活性导致 雄激素受体（AR）基因在不同时间的调节， 肝脏 2)雄激素受体基因的DNA序列的解剖， 在受体的肝脏表达中起关键作用。 3)描述负责雄激素抑制的顺式元件， SMP-2基因。 4)与雄激素不同的其他顺式元件的可能作用 反应元件，可能参与年龄依赖性调节， SMP-2基因。 5)雄激素受体和其他非受体转录的作用 SMP-2基因年龄依赖性调控中的调节蛋白 表情 感兴趣的DNA响应元件将通过基因识别。 转移到含有雄激素受体的细胞中。 额外的顺式元件 对成熟和衰老变化的反应将通过DNA检测 转染到来自年轻和老年大鼠的培养肝细胞中。 推定 转录反式激活因子调节差异时间表达 肝脏中AR基因的表达，以及一些可能参与 衰老过程中SMP-2基因的调控，将使用互补的 特异性蛋白质-DNA结合和体外转录的分析。 的 DNA结合研究将利用西南印迹，迁移率变化和 DNA酶1足迹分析。 肝细胞核转录能力 将比较年轻大鼠和老年大鼠的提取物， 支持SMP-2启动子指导体外转录合适的 模板 这些研究的结果有望提供重要的新见解 在衰老过程中的基因调控。

Differential expression of androgen receptor (AR) mRNA in rat liver during maturation and aging directly correlates with androgen responsiveness of the young-adult male liver, and androgen insensitivity during prepuberty and senescence. A 31 kDa androgen-repressible liver protein, designated as SMP-2, is expressed at relatively high abundance during the periods of hepatic androgen insensitivity compared to its very low level of expression in the androgen-responsive adult male. Nuclear run off studies show that age-dependent reactivation and androgen-mediated repression of SMP-2 are primarily regulated through altered rates of gene transcription. The proposed studies have been designed to examine the following: 1) Identification of putative transcription transactivators whose differential expression/activity during maturation and aging results in the differential temporal regulation of the androgen receptor (AR) gene in the liver. 2) Dissection of the DNA sequences of the androgen receptor gene which play critical roles in hepatic expression of the receptor. 3) Delineation of the cis elements responsible for androgenic repression of the SMP-2 gene. 4) The possible role of additional cis elements, distinct from androgen response elements, which may participate in the age-dependent regulation of the SMP-2 gene. 5) The role of androgen receptor and other non-receptor transcription regulatory proteins in the age-dependent regulation of SMP-2 gene expression. The DNA response elements of interest will be identified through gene transfer into cells containing androgen receptor. Additional cis elements responding to changes in maturation and aging will be detected via DNA transfection into cultured hepatocytes from young and old rats. Putative transcription transactivators regulating differential temporal expression of the AR gene in the liver, as well as some that are possibly involved in SMP-2 gene regulation during aging, will be identified using complementary analyses of specific protein-DNA binding and in vitro transcription. The DNA binding studies will utilize Southwestern blotting, mobility shift and DNase 1 footprinting analyses. Transcription competence of liver nuclear extracts from young and old rats will be compared in their ability to support SMP-2 promoter-directed in vitro transcription of appropriate templates. The results of these studies are expected to provide important new insights into gene regulation during aging.