The Role of PARP-1 in Hormone-Regulated Transcription

雌激素，如17(3-雌二醇)，在正常的生理过程中发挥重要作用，如 以及疾病状态。这些研究的长远目标，是要更深入了解 雌二醇通过雌激素受体调控基因表达的分子机制 α(Era)，一种受配体调节的、与DMA结合的转录因子。特别是，我们感兴趣的是如何 ERA的活性受其相关的共调节蛋白在染色质环境中的调节 原子核。在这方面，我们的研究重点是聚(ADP-核糖)聚合酶-1(PARP-1)，a 染色质依赖的转录辅助调节因子，以及组蛋白ADP核糖结合变异体MacH2A 与PARP-1结合。PARP-1是聚(ADP-核糖)聚合酶家族中含量最丰富的成员，是一种 催化靶蛋白上ADP-核糖链聚合的染色质结合核酶 来自供体烟酰胺腺嘌呤二核苷酸(NAD+)分子。最近的研究揭示了重要的 PARP-1作为ERA协同调节因子的作用。我们的广泛假设是，PARP的协同调节活性- 在E2调节的启动子由(1)局部染色质环境(例如，染色质 组成、组蛋白修饰)以及(2)PARP-1、ERA、其他 共同调节剂，以及染色质的成分。我们已经计划了一系列实验，使用 多学科方法，包括生化、生物物理、基于细胞和 基因组学方法将测试我们的广泛假设并解决三个具体目标：(1)定义集合 利用基因组研究PARP-1和宏H_2A共同调节的直接靶点的E2调节基因 方法，(2)确定E2染色质依赖调节的分子机制 PARP-1和宏H_2A通过基于细胞的分析确定靶基因，以及(3)测定生化 PARP-1和PARP-1对Era转录活性的染色质依赖性调控机制 用生化分析法检测大分子过氧化氢。这部作品的一个基本主题是 核内NAD+代谢与PARP-1和宏H_2A活性的调节。总的来说，这些研究 将对PARP-1的S共调节活性的分子机制提供新的见解，特别是那些 在含有大分子H2A的染色质的背景下，与ERA依赖的转录相关。此外，这些 研究将为核NAD+信号在激素调节转录中的作用提供新的见解。 这是一个令人兴奋的新领域，现在才开始被理解。鉴于PARP-1和ERA在 对于人类疾病，我们的研究也可能带来利用这些因素作为治疗靶点的新方法。

Estrogenic hormones, such as 17(3-estradiol (E2), play important roles in normal physiologic processes, as well as disease states. The long-term objective of these studies is to gain a better understanding of the molecular mechanisms underlying the control of gene expression by E2 acting through estrogen receptor alpha (ERa), a ligand-regulated, DMA-binding transcription factor. In particular, we are interested how the activity of ERa is modulated by its associated coregulatory proteins in the chromatin environment of the nucleus. In this regard, we are focusing our studies on poly(ADP-ribose) polymerase-1 (PARP-1), a chromatin-dependent transcriptional coregulator, and macroH2A, an ADP-ribose-binding histone variant that binds to PARP-1. PARP-1, the most abundant member of a family of poly(ADP-ribose) polymerases, is a chromatin-binding nuclear enzyme that catalyzes the polymerization of ADP-ribose chains on target proteins from donor nicotinamide adenine dinucleotide (NAD+) molecules. Recent studies have revealed important roles for PARP-1 as a coregulator of ERa. Our broad hypothesis is that the coregulatory activity of PARP- 1 at E2-regulated promoters is determined by (1) the local chromatin environment (e.g., chromatin composition, histone modifications) and (2) physical and functional interactions among PARP-1, ERa, other coregulators, and components of chromatin. We have planned a series of experiments using a multidisciplinary approach with a complementary set of biochemical, biophysical, cell-based, and genomic approaches that will test our broad hypothesis and address three specific aims: (1) Define the set of E2-regulated genes that are direct targets for coregulation by PARP-1 and macroH2A by using genomic approaches, (2) Determine the molecular mechanisms underlying the chromatin-dependent regulation of E2 target genes by PARP-1 and macroH2A by using cell-based assays, and (3) Determine the biochemical mechanisms underlying the chromatin-dependent regulation of ERa transcriptional activity by PARP-1 and macroH2A by using biochemical assays. An underlying theme in this work is the connection between nuclear NAD+ metabolism and the regulation of PARP-1 and macroH2A activity. Collectively, these studies will provide new insights into the molecular mechanisms of PARP-1's coregulatory activity, especially those relevant to ERa-dependent transcription in the context of macroH2A-containing chromatin. In addition, these studies will provide new insights into the role of nuclear NAD+ signaling in hormone-regulated transcription, an exciting new area that is only now beginning to be understood. Given the roles of PARP-1 and ERa in human disease, our studies could also lead to new ways to exploit these factors as therapeutic targets.