Implications of PARP1 in myelodysplastic syndromes and targeted therapy

PARP1 在骨髓增生异常综合征和靶向治疗中的意义

• 批准号: 10624340
• 负责人: Dang Hai Nguyen
• 金额: $ 48.36万
• 依托单位: UNIVERSITY OF MINNESOTA
• 依托单位国家: 美国
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-05-20 至 2027-04-30
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10624340
• 关键词: ADP ribosylation; Address; Biological Markers; Biology; Blood; Blood typing procedure; Bone Marrow; CD34 gene; Cell Death; Cells; Clinic; Clonal Hematopoietic Stem Cell; DNA; DNA Damage; Data; Disease; Dysmyelopoietic Syndromes; Enzymes; FDA approved; Genes; Genetic Predisposition to Disease; Genetic Transcription; Genome; Genomic Instability; Genomics; Hematological Disease; Hematopoietic; Heterozygote; Human; Hybrids; In Vitro; Ineffective Hematopoiesis; Laboratories; Lead; Link; Modality; Modeling; Molecular; Monitor; Mononuclear; Mus; Mutate; Mutation; Myelogenous; PTPRC gene; Patients; Play; Poly(ADP-ribose) Polymerase Inhibitor; Poly(ADP-ribose) Polymerases; Prevalence; Production; Prognosis; Proteins; Proteomics; RNA; RNA Splicing; Regulation; Route; SRSF2 gene; SS DNA BP; Secondary acute myeloid leukemia; Secondary to; Signal Transduction; Single-Stranded DNA; Site; Source; Spliceosomes; Structure; Testing; Therapeutic; Translating; Transplantation; acquired bone marrow failure; bone marrow failure syndrome; cytopenia; efficacy evaluation; established cell line; genome-wide; high risk; in vivo; mouse model; mutant; novel therapeutics; overexpression; peripheral blood; pre-clinical; progenitor; progression risk; public health relevance; recruit; replication factor A; response; sensor; stem cells; targeted treatment

PROJECT SUMMARY/ABSTRACT Myelodysplastic syndromes (MDS), a heterogenous group of clonal hematopoietic stem cell disorders, are an acquired bone marrow failure syndrome. MDS is characterized by ineffective hematopoiesis resulting in peripheral blood cytopenia and progenitor expansion. Genes encoding for RNA splicing factors (U2AF1, SF3B1, SRSF2, and ZRSR2) are frequently mutated and occur in the founding clones of MDS, representing a unique class of genetic vulnerability for targeted therapy. However, despite the prevalence of spliceosome mutations, how such mutations impact different cellular mechanisms are largely unclear. Recent studies by us and others suggest that R-loops, a group of transcription intermediates containing RNA:DNA hybrids and displaced single- stranded DNA, are a source of genomic instability induced by different spliceosome mutants. In the preliminary studies leading to this application, we find that PARP1 is activated by R-loops and it plays a key role in suppressing R-loop-associated DNA damage. Furthermore, we show that MDS-associated RNA splicing factor mutations promote R-loop accumulation and render cells sensitive to PARP inhibition. These exciting findings lead us to hypothesize that PARP1 is a key sensor of R-loops and a critical suppressor of R-loop-associated DNA damage. Furthermore, aberrant R-loop accumulation represents a new targetable vulnerability in MDS- associated splicing factor mutant cells, making PARP inhibition an attractive way to target R-loop vulnerability in MDS. Finally, since PARP inhibitors achieved limited FDA approval in different diseases, repurposing PARP inhibitors to treat MDS patients harboring RNA splicing factor mutations may provide the fastest route to translate our findings to the clinics. To test these hypotheses, in Aim 1, we will elucidate mechanisms by which PARP1 is activated by R-loops. In Aim 2, we will identify global PARP1 substrates and R-loop distribution landscape in U2AF1-mutant cells, providing a proteomic and genomic view of how PARP1 regulates R-loops. In Aim 3, we will evaluate whether PARP inhibitor, olaparib, can selectively eliminate MDS-associated splicing mutant cells in vitro and in vivo. Together, these studies will mechanistically explain how R-loops are sensed by PARP1 in splicing mutant cells, reveal how PARP1 guards cells against R-loop-associated genomic instability, and address whether R-loop-associated vulnerability in spliceosome-mutant MDS cells can be exploited by PARP inhibitors as targeted MDS therapy. The combined expertise in R-loops, PARP1, DNA damage response and spliceosome mutations in MDS (Nguyen laboratory), PARP regulation by proteomic approach (Leung laboratory, co-I), and MDS GEMM mouse models of U2AF1 and SRSF2 mutations (Lee laboratory, co-I) provides us the unique opportunity to characterize PARP1 function in cells expressing MDS-associated mutations. These studies will not only significantly advance our understanding of R-loop biology and PARP1 signaling, but also repurpose the use of FDA-approved PARP inhibitors in targeted therapy for MDS patients harboring RNA splicing factor mutations by exploiting R-loop-associated vulnerability.

项目概要/摘要 骨髓增生异常综合征 (MDS) 是一组异质性克隆性造血干细胞疾病，是一种 获得性骨髓衰竭综合征。 MDS 的特点是无效造血，导致 外周血细胞减少和祖细胞扩张。编码 RNA 剪接因子的基因（U2AF1、SF3B1、 SRSF2 和 ZRSR2）经常发生突变，并出现在 MDS 的创始克隆中，代表了一种独特的 靶向治疗的遗传脆弱性类别。然而，尽管剪接体突变普遍存在， 这些突变如何影响不同的细胞机制目前尚不清楚。我们和其他人最近的研究 R-loops 是一组含有 RNA:DNA 杂合体和置换单链的转录中间体。 链状 DNA 是由不同剪接体突变体诱导的基因组不稳定的来源。在预赛中 在导致该应用的研究中，我们发现 PARP1 是由 R 环激活的，并且它在 抑制 R 环相关的 DNA 损伤。此外，我们还发现MDS相关RNA剪接因子 突变促进 R 环积累并使细胞对 PARP 抑制敏感。这些令人兴奋的发现 使我们假设 PARP1 是 R 环的关键传感器和 R 环相关的关键抑制子 DNA 损伤。此外，异常的 R 环累积代表了 MDS 中的一个新的可针对的漏洞—— 相关剪接因子突变细胞，使得 PARP 抑制成为一种针对 R 环脆弱性的有吸引力的方法 MDS。最后，由于 PARP 抑制剂在不同疾病中获得了有限的 FDA 批准，重新利用 PARP 治疗携带RNA剪接因子突变的MDS患者的抑制剂可能提供最快的转化途径 我们将研究结果传达给诊所。为了检验这些假设，在目标 1 中，我们将阐明 PARP1 的机制 由 R 环激活。在目标 2 中，我们将确定全球 PARP1 底物和 R 环分布格局 U2AF1 突变细胞，提供 PARP1 如何调节 R 环的蛋白质组学和基因组学视图。在目标 3 中，我们 将评估 PARP 抑制剂 olaparib 是否可以选择性消除 MDS 相关剪接突变细胞 体外和体内。这些研究将共同​​从机制上解释 R 环如何被 PARP1 感知 剪接突变细胞，揭示 PARP1 如何保护细胞免受 R 环相关基因组不稳定性的影响，并解决 PARP 抑制剂是否可以利用剪接体突变 MDS 细胞中与 R 环相关的脆弱性 作为MDS的靶向治疗。 R 环、PARP1、DNA 损伤反应和剪接体方面的综合专业知识 MDS 突变（Nguyen 实验室）、通过蛋白质组学方法进行的 PARP 调节（Leung 实验室，co-I）以及 U2AF1 和 SRSF2 突变的 MDS GEMM 小鼠模型（Lee 实验室，co-I）为我们提供了独特的 有机会表征表达 MDS 相关突变的细胞中的 PARP1 功能。这些研究将 不仅显着增进了我们对 R 环生物学和 PARP1 信号传导的理解，而且还重新利用了 使用 FDA 批准的 PARP 抑制剂对携带 RNA 剪接因子的 MDS 患者进行靶向治疗 利用 R 环相关的漏洞进行突变。