The Role of PARP-1 in Hormone-Regulated Transcription

雌激素，如17 β-雌二醇（E2），在正常的生理过程中起着重要的作用， 以及疾病状态。这些研究的长期目标是更好地了解 E2通过雌激素受体调控基因表达的分子机制 ER α是一种配体调节的DMA结合转录因子。我们特别感兴趣的是， ER α的活性由其在细胞核染色质环境中的相关共调节蛋白调节。 原子核在这方面，我们集中研究聚（ADP-核糖）聚合酶-1（PARP-1）， 和macroH 2A，一种ADP-核糖结合组蛋白变体， 与PARP-1结合。PARP-1是聚（ADP-核糖）聚合酶家族中最丰富的成员，是一种高分子聚合酶。 一种染色质结合的核酶，催化ADP-核糖链在靶蛋白上的聚合 来自供体烟酰胺腺嘌呤二核苷酸（NAD+）分子。最近的研究表明， PARP-1作为ER α的共调节因子的作用。我们广泛的假设是，PARP的协同调节活性- 1在E2调节的启动子上的表达由（1）局部染色质环境（例如，染色质 组成，组蛋白修饰）和（2）PARP-1，ER α，其他 辅调节子和染色质组分。我们计划了一系列实验， 多学科的方法与一套互补的生物化学，生物物理，细胞为基础的， 基因组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 E2调节基因是PARP-1和macroH 2A共调节的直接靶点， 方法：（2）确定染色质依赖性E2调节的分子机制 通过使用基于细胞的测定，通过PARP-1和macroH 2A检测靶基因，和（3）确定生物化学 PARP-1对ER α转录活性的染色质依赖性调节机制， macroH 2A，通过使用生物化学测定。这部作品的一个潜在主题是 核NAD+代谢和PARP-1和macroH 2A活性的调节。总的来说，这些研究 将为PARP-1的共调节活性的分子机制提供新的见解，特别是那些 在含有macroH 2A的染色质的背景下与ER α依赖性转录相关。另外这些 这些研究将为细胞核NAD+信号在转录调控中的作用提供新的见解， 一个令人兴奋的新领域，现在才开始被理解。考虑到PARP-1和ERa在 人类疾病，我们的研究也可能导致新的方法来利用这些因素作为治疗目标。

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.