CARCINOGENS AND CHROMATIN STRUCTURE AND FUNCTION

核蛋白的聚腺苷二磷酸-核糖基化修饰是最初的 细胞对化学物质造成的DNA损伤的反应。聚(ADP-核糖) 聚合酶(PADPRP)的催化活性完全依赖于DNA和 它的活性与细胞内链断裂的数量直接相关 DNA因此，当细胞暴露在化学致癌物中时，就会产生 细胞NAD的即刻下降和伴随的快速和短暂的增加 在聚腺苷二磷酸核糖化核蛋白中。 该项目的最新进展包括克隆、测序和 该酶基因在人和人体内的高效表达 小鼠的系统。使用瞬时转染法的初步数据表明 高表达PADPRP的细胞DNA修复速度加快。我们 也能够绘制出这一基因在两个基因中的精确染色体位置 人和老鼠。 在续订期间，我们打算利用分子和 获得的生化数据，以更好地阐明和表征 DNA修复机制中的ADP-核糖化。Aim I中的方法使用 包括反义和核酶在内的多种分子方法 表达，以实验调节细胞中的ADP核糖化潜能 受到DNA链断裂的影响并通过使用 精确测量优先基因修复和修复的新方法 用新的质粒法测定重组酶活力。 ADP核糖化的核靶标是AIM II的重点。新的 这里将使用分子信息来关联PADPRP的结构(和 其核蛋白受体)发挥作用。例如，c-fos是一个 PADPRP的核受体，也可被链- 破坏化学物质。反义调控的PADPRP活性将用于 阐述了FOS的PADPRP的生物学功能，并以 用于其他核蛋白受体的方法 续订期限。

The poly ADP-ribosylation modification of nuclear proteins is the initial cellular response to DNA damage caused by chemicals. Poly(ADP-ribose) polymerase (PADPRP) catalytic activity is absolutely dependent upon DNA and its activity is directly correlated with the number of strand breaks in DNA. Thus, when cells, are exposed to chemical carcinogens, there is an immediate drop in cellular NAD and concomitant rapid and transient increase in poly ADP-ribosylated nuclear proteins. Recent progress on this project involved the cloning, sequencing, and hyperexpression of transfected genes for this enzyme in both human and murine systems. Preliminary data using transient transfection indicated that cells hyperexpressing PADPRP have increased rates of DNA repair. We also were able to map the precise chromosomal loci for this gene in both human and mouse. During the renewal period, we intent to utilize the molecular and biochemical data obtained to better clarify and characterize the role of ADP-ribosylation in DNA repair mechanisms. Methods in Aim I utilize a variety of molecular approaches including antisense and ribozyme expression, to experimentally modulate ADP-ribosylation potential in cells subjected to DNA strand breaks and assess the effects of this by utilizing new methods for precisely measuring preferential gene repair and recombinase activity using novel plasmid assays. Nuclear targets for ADP ribosylation are the focus of Aim II. The new molecular information will be used here to relate structure of PADPRP (and its nuclear protein acceptors) to function. For example, c-fos is a nuclear acceptor for PADPRP and also transcriptionally activated by strand- breaking chemicals. PADPRP activity modulated by antisense will be used to address the biological function of the PADPRP of fos, and as an example of approaches to be used for other nuclear protein acceptors during the renewal period.