REGULATION OF CYTOCHROME P450 BIOSYNTHESIS

描述（研究者摘要）：本提案的总体目标是 为了理解经典诱导剂的分子机制， 苯巴比妥（PB），增加细胞色素P450的基因表达。 的 本建议的具体目标是确定和描述 顺式和反式作用因子介导的苯巴比妥诱导， CYP2B和CYP2C亚家族。 这一领域的进展受到阻碍， 缺乏用于苯巴比妥诱导的连续细胞培养模型系统。 然而，实验室已经证明，将DNA转染到大鼠中， 原位肝脏已被证明是一种简单且可重复的方法， CYP2B2基因的表达，并用于确认CYP2B2 DNA片段 可以介导苯巴比妥的反应性。 缺失和位点特异性 突变将用于鉴定苯巴比妥响应元件 （PBRE）在CYP2B2 DNA片段。 经典的重组DNA技术 将用于确定对监管重要的区域。 的影响 还将分析苯巴比妥对PBRE染色质结构的影响， 并且天然染色质中调节因子的结合将是 测定 小鼠中的同源重组将被用于评估在小鼠中的同源重组。 所鉴定的元件的体内功能。 兔和小鼠CYP2C基因将 通过序列相似性和原位杂交筛选PBRE 转染测定，并最终通过小鼠中的靶向缺失。 苯巴比妥诱导小鼠CYP2C基因表达的特点 与CYP2B基因进行比较，以确定是否存在不同的诱导机制 与这两个基因有关。 这些研究应提供详细的 在分子水平上理解功能PBRE。

DESCRIPTION (Investigator's Abstract): The overall goal of this proposal is to understand the molecular mechanisms by which the classical inducer, phenobarbital (PB), increases gene expression of cytochromes P450. The specific objectives of this proposal are to identify and characterize the cis-and trans-acting factors that mediate phenobarbital induction in the CYP2B and CYP2C subfamilies. Progress in this area has been hindered by the lack of continuous cell culture model systems for phenobarbital induction. However, the laboratory has demonstrated that transfection of DNA into rat liver in situ has been shown to be a simple and reproducible method for expression of CYP genes and was used to confirm that a CYP2B2 DNA fragment could mediate phenobarbital responsiveness. Deletion and site-specific mutation will be used to identify the phenobarbital-responsive elements (PBRE) in the CYP2B2 DNA fragment. Classical recombinant DNA techniques will be used to identify regions important for regulation. The effect of phenobarbital on the chromatin structure of the PBRE will also be analyzed, and binding of the regulatory factors in native chromatin will be determined. Homologous recombination in mice will be used to assess the in vivo function of the identified elements. Rabbit and mouse CYP2C genes will be screened for PBRE's by sequence similarity and by the in situ transfection assay, and ultimately by targeted deletions in mice. Characteristics of phenobarbital induction of CYP2C genes in the mouse will be compared with CYP2B genes to determine if different induction mechanisms are involved for the two genes. These studies should provide a detailed understanding of a functional PBRE at the molecular level.