Hormone Receptor Regulation of RNA Polymerase III

项目摘要 类固醇受体是核受体（NR）转录因子的一个亚类，仅在脊椎动物中发现 并调节生物体发育和繁殖等基本功能，同时也影响衰老， 肿瘤发生和癌症进展。小的亲脂性激素与雌激素的类固醇受体（ER-1）结合。 α和ER-β）、孕酮（PR）、糖皮质激素（GR）和雄激素（AR）并传递它们的信号 通过基因调控。由于这些小分子可以合成修饰和制造， 的药物提供关键药物的疾病，包括代谢紊乱，生殖， 癌症治疗NR的作用机制主要是在RNA聚合酶II（Pol II）转录 基因包括蛋白质编码mRNA和小/长非编码RNA。多个NR以复合物形式作用于DNA 激活或抑制Pol II转录。然而，NR控制的细胞转录组通常并不总是紧密地结合在一起。 与蛋白质组相关，由于转录后调控，这是不完全理解的。我们有 通过RNA聚合酶III（Pol III）的调节，发现了第二层协调的NR活性 转录基因Pol III转录对于mRNA翻译成包括tRNA在内的蛋白质所必需的小RNA 和5S rRNA，是控制细胞生长、干细胞、衰老和癌症的主要节点。负调控 Pol III的表达通常是通过保守的阻遏物Maf 1。关于核反应堆如何调节， Pol III在更复杂的哺乳动物细胞和生物体中。我们通过对PR的全基因组分析发现， ER+PR+乳腺癌细胞系和PR定位于多个tRNA基因的肿瘤中的染色质结合。PR 与Pol III复合物结合并降低tRNA水平和蛋白质合成。Progressive招聘PR 视黄酸受体α（RARα）与tRNA基因在类似NR的保守DNA序列附近 结合半位点。我们的假设是，PR通过与tRNA基因的串扰来调节Pol III转录。 RARα和Maf 1的募集导致靶tRNA基因水平降低和选择性翻译。目的 1将确定PR如何与tRNA基因相关，RARα和其他类固醇受体的作用，以及NR 结合半位点。目的二是确定Maf 1在PR调节Pol III转录中的作用。目标3将定义 酶诱导的tRNA库变化及其对翻译效率的影响。Pol III的调节是 与Pol II相比，其研究远远不足，并且对于正常和致癌细胞表型至关重要。成果 这项研究将定义NR在Pol III基因上作用的新机制，这将有助于解释i） 有助于选择性mRNA翻译激素调节，和ii）NR如何会聚于多个细胞 在一些实施方案中，本发明的组合物可通过使用聚合酶来影响细胞生长、分化、干性和肿瘤进展。

Project summary Steroid receptors are a subset of nuclear receptor (NR) transcription factors that are found only in vertebrates and regulate essential functions such as organismal development and reproduction, while also impacting aging, tumorigenesis, and cancer progression. Small lipophilic hormones bind to steroid receptors for estrogens (ER- alpha and ER-beta), progesterone (PR), glucocorticoids (GR), and androgens (AR) and transmit their signal through gene regulation. Since these small molecules can be synthetically modified and manufactured, a variety of pharmaceutical drugs provide critical medicines for diseases including metabolic disorders, reproduction, and cancer treatment. NR mechanism of action has been mostly studied at RNA polymerase II (Pol II) transcribed genes including protein-coding mRNAs and small/long non-coding RNAs. Multiple NRs act in complexes on DNA to activate or repress Pol II transcription. However, NR controlled cell transcriptomes are often not always tightly correlated with the proteome due to post-transcriptional regulation that is not completely understood. We have uncovered a second layer of coordinated NR activity through regulation of RNA Polymerase III (Pol III) transcribed genes. Pol III transcribes small RNAs essential for translation of mRNAs into protein including tRNAs and 5S rRNA and is a major node for controlling cell growth, stem cells, aging, and cancer. Negative regulation of Pol III is commonly through the conserved repressor Maf1. Very little is known concerning how NRs regulate Pol III in more complex mammalian cells and organisms. We discovered using genome-wide analyses of PR chromatin binding in ER+PR+ breast cancer cell lines and tumors that PR localizes at multiple tRNA genes. PR associates with the Pol III complex and decreases tRNA levels and protein synthesis. Progesterone recruits PR and retinoic acid receptor alpha (RARα) to tRNA genes near a conserved DNA sequence resembling an NR binding half site. Our hypothesis is that PR regulates Pol III transcription of tRNA genes through crosstalk with RARα and recruitment of Maf1 resulting in decreased levels of target tRNA genes and selective translation. Aim 1 will determine how PR associates at tRNA genes, the role of RARα and other steroid receptors, and the NR binding half site. Aim 2 will determine the role of Maf1 in PR modulation of Pol III transcription. Aim 3 will define hormone-induced changes in the tRNA pool and the impact on translational efficiency. Regulation of Pol III is vastly understudied compared to Pol II and crucial for normal and oncogenic cell phenotypes. Results of this study will define a novel mechanism of NR action at Pol III genes that will help explain i) an additional layer of hormone regulation that contributes to selective mRNA translation, and ii) how NRs converge on multiple cell polymerases to impact cell growth, differentiation, stemness, and tumor progression.