Novel small molecules to treat degenerative lung and blood diseases

项目总结/摘要。端粒疾病包括由调节端粒生物学的基因突变引起的一系列罕见和致命的综合征。这些包括严重的儿童血液疾病先天性角化不良（DC）和迟发性肺部疾病，如肺纤维化（PF）。尽管在过去的二十年中基因和途径发现取得了进展，但这些知识尚未转化为治疗方法，也没有治愈性治疗方法。端粒疾病的发病机制的中心是端粒酶的破坏，端粒酶是一种核糖核蛋白复合物，在人类细胞中使端粒变短。该项目的长期目标是治疗性恢复端粒酶的长非编码RNA组分TERC，TERC在DC，PF和其他端粒疾病中失调。公共/健康/相关性是广泛的。TERC水平决定了人类干细胞中的端粒酶活性水平，进而决定了组织在生命周期中的再生能力。TERC中常见的遗传变异与心血管和肺部疾病有关。破坏TERC的突变会导致孟德尔疾病，这些疾病在不同年龄段出现，包括骨髓衰竭和慢性肺部疾病。最近在DC和PF中的遗传研究揭示了可能靶向操纵TERC的因子，特别是转录后RNA加工因子。基于这些新的见解，该项目的目标是开发一种RNA聚合酶的小分子抑制剂，这种RNA聚合酶使TERC不稳定，称为PAPD 5。中心假设是存在治疗窗口，其中PAPD 5抑制可以恢复TERC水平和端粒酶功能。如果成功的话，这种策略可能为端粒疾病提供一种新的系统治疗方法。将通过追求两个特定目标来检验中心假设：（1）设计、合成和表征改进的PAPD 5抑制剂，以及（2）确定PAPD 5抑制剂的先导系列，用于进一步的临床前开发。其目的是响应NHLBI催化剂赠款计划，以确定一个领先的化合物系列对肺部和血液疾病的治疗发展。该提案利用了一个创新的管道，该管道涵盖了高通量筛选到体内疗效，从而能够对新型PAPD 5抑制剂进行严格的临床前评估。在第一个目标下，药物化学、生物化学测定和患者来源的诱导多能干细胞（iPSC）模型将促进小分子PAPD 5抑制剂的发展。在第二个目标下，常规的先导物优化测定将与新的造血干细胞异种移植模型结合，以使得能够在疾病相关的人类干细胞中通过PAPD 5抑制剂体内评估端粒延长能力。该方法是创新的，因为它利用了新的方法和见解，使重点从核酸递送转向靶向非编码RNA生物合成途径，作为治疗性调节端粒酶的一种手段。这项拟议中的研究意义重大，因为它有望产生操纵端粒酶的策略，以治疗广泛的退行性肺和血液疾病，对此没有治愈性疗法。

PROJECT SUMMARY/ABSTRACT. Telomere diseases encompass a spectrum of rare and fatal syndromes caused by mutations in genes regulating telomere biology. These include the severe childhood blood disorder dyskeratosis congenita (DC) and later-onset lung diseases such as pulmonary fibrosis (PF). Despite progress in gene and pathway discovery in the past two decades, there has been no translation of this knowledge into therapies, and there are no curative treatments. Central to the pathogenesis of telomere diseases is disruption of telomerase, the ribonucleoprotein complex that replenishes telomeres in human cells. The long-term goal of this project is to therapeutically restore the long non-coding RNA component of telomerase, TERC, which is dysregulated in DC, PF and other telomere diseases. The public/health/relevance is broad. TERC levels determine telomerase activity levels in human stem cells, and in turn the regenerative capacity of tissues over the lifespan. Common genetic variants in TERC are associated with cardiovascular and pulmonary diseases. Mutations that disrupt TERC cause Mendelian disorders presenting across the age spectrum including bone marrow failure and chronic lung diseases. Recent genetic studies in DC and PF shed new light on factors that might be targeted to manipulate TERC, specifically post-transcriptional RNA processing factors. Based on these new insights, the goal of this project is to develop small molecule inhibitors to an RNA polymerase that destabilizes TERC, called PAPD5. The central hypothesis is that there is a therapeutic window wherein PAPD5 inhibition can restore TERC levels and telomerase function. If successful, this strategy may provide a novel class of systemic therapies for telomere diseases. The central hypothesis will be tested by pursuing two Specific Aims: (1) Design, synthesize, and characterize improved PAPD5 inhibitors, and (2) Identify a lead series of PAPD5 inhibitors for further pre-clinical development. The aims are responsive to the NHLBI Catalyze grants program, to identify a lead compound series toward therapeutic development for lung and blood diseases. The proposal takes advantage of an innovative pipeline that spans high-throughput screening to in vivo efficacy, enabling rigorous pre-clinical evaluation of novel PAPD5 inhibitors. Under the first aim, medicinal chemistry, biochemical assays, and patient-derived induced pluripotent stem cell (iPSC) models will advance small molecule PAPD5 inhibitors. Under the second aim, conventional lead optimization assays will be coupled to a novel hematopoietic stem cell xenotransplantation model, to enable in vivo assessment of telomere elongating capacity by PAPD5 inhibitors in disease-relevant human stem cells. The approach is innovative because it leverages new methods and insights to allow a critical shift in focus from nucleic acid delivery to targeting a non-coding RNA biogenesis pathway, as a means of therapeutically modulating telomerase. The proposed research is significant, because it is expected to yield strategies to manipulate telomerase to treat a broad range of degenerative lung and blood disorders, for which there are no curative therapies.