AGE & HORMONE-DEPENDENT REGULATION OF A HEPATIC PROTEIN

雄激素受体(AR)mRNA在大鼠肝脏中的差异表达 成熟和老化与雄激素反应直接相关 青春期前的青壮年男性肝脏和雄激素不敏感 和衰老。一种31 kDa的雄激素抑制型肝蛋白，命名为 SMP-2的表达丰度相对较高 与其非常低的表达水平相比，肝脏雄激素不敏感 对雄激素敏感的成年雄性。核径流研究表明 SMP-2的年龄依赖性重新激活和雄激素介导的抑制是 主要通过改变基因转录速率来调节。这个 拟议的研究旨在审查以下几个方面： 1)鉴定其可能的转录反式激活因子 成熟和衰老过程中的差异表达/活性导致 雄激素受体(AR)基因在大鼠脑内的时间差异调节 肝脏。 2)雄激素受体基因的DNA序列分析 受体在肝脏表达中的关键作用。 3)描述负责雄激素抑制的顺式元件 SMP-2基因。 4)不同于雄激素的附加顺式元件的可能作用 反应元件，可能参与年龄相关的调节 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反应元件将通过基因识别 转移到含有雄激素受体的细胞中。其他顺序性要素 对成熟和衰老变化的反应将通过DNA进行检测 将其转入培养的幼年和老年大鼠肝细胞中。推定 转录反式激活因子调控差异时间表达 肝脏中的AR基因，以及一些可能参与 SMP-2基因在衰老过程中的调控，将使用互补 特异性蛋白质-DNA结合分析和体外转录。这个 DNA结合研究将利用西南印迹、迁移率漂移和 DNase1足迹分析。肝细胞核的转录能力 幼年和老年大鼠的提取物将在它们的能力方面进行比较 支持SMP-2启动子引导的适当体外转录 模板。 这些研究的结果有望提供重要的新见解 在衰老过程中进行基因调控。

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.