Investigation of the Role of BAP1 in Normal and Malignant Hematopoiesis

BAP1 在正常和恶性造血中的作用研究

• 批准号: 8595542
• 负责人: Lindsay Marie LaFave
• 金额: $ 4.22万
• 依托单位: SLOAN-KETTERING INST CAN RESEARCH
• 依托单位国家: 美国
• 财政年份: 2013
• 资助国家: 美国
• 起止时间: 2013-07-01 至 2015-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8595542
• 关键词: Acute Myelocytic Leukemia; Alleles; BRCA1 Associated Protein-1; Biological; Biological Assay; Biological Models; Cell surface; Cells; Chromatin; Clinical; Collection; Comb animal structure; Complex; Data; Defect; Deubiquitination; Disease; Disease Progression; Down-Regulation; Dysmyelopoietic Syndromes; EZH2 gene; Enzymes; Epigenetic Process; Flow Cytometry; Future; Gene Expression; Gene Expression Regulation; Genes; Genetic; Genetic Transcription; Genomics; Goals; Hematopoiesis; Hematopoietic; Histone H2A; Histones; Human; Human Characteristics; In Vitro; Investigation; Knock-out; Knockout Mice; Lysine; Malignant - descriptor; Malignant Neoplasms; Mediating; Mesothelioma; Modeling; Mus; Mutate; Mutation; Myeloproliferation; Oncogenic; Outcome; Pancytopenia; Pathogenesis; Patients; Pharmaceutical Preparations; Phenotype; Polycomb; Proteins; Regulation; Renal Cell Carcinoma; Research; Risk; Role; Sampling; Somatic Mutation; Stem cell transplant; Stem cells; System; Testing; Therapeutic; Therapeutic Agents; Translating; Transplantation; Tumor Suppressor Proteins; Up-Regulation; Uveal Melanoma; Work; in vitro Model; in vivo; inhibitor/antagonist; loss of function; mouse model; new therapeutic target; novel; novel therapeutics; outcome forecast; pre-clinical; progenitor; public health relevance; sex; small hairpin RNA; stem

DESCRIPTION (provided by applicant): This project aims to characterize the role of BRCA1 associated protein-1 (BAP1) in normal and malignant hematopoiesis. BAP1 has been found to be mutated and downregulated in human myelodysplastic syndromes (MDS) consistent with BAP1 functioning as a novel tumor suppressor in the hematopoietic compartment. The mechanism(s) of action and the context in which BAP1 acts remains largely unknown. Our collaborators have recently shown that mice with whole body conditional loss of BAP1 manifest pancytopenia which is a characteristic of human MDS. Previous work by our lab and others has demonstrated that BAP1, an enzyme that has a role in deubiquitination of histone H2A at lysine 119, forms a ternary complex with ASXL1. ASXL1 is commonly mutated in human MDS and acute myeloid leukemia (AML) and ASXL1 mutations are predictors of poor patient outcome. We have shown that while BAP1 and ASXL1 do interact in hematopoietic cells, these proteins have independent effects on target gene expression and global histone regulation. Whereas loss of ASXL1 results in upregulation of expression HOXA cluster and decreased Polycomb Repressive Complex 2 (PRC2) function, BAP1 depletion increases global H3K27me3 and represses HOXA gene expression. My central hypotheses are: (1) Genetic deletion of BAP1 in the hematopoietic specific compartment causes abnormal hematopoiesis due to a stem and/or progenitor cell defect, (2) BAP1 regulates the PRC2 complex and MDS patients with BAP1 downregulation will be sensitive to EZH2 inhibitors, and (3) BAP1 could collaborate with other oncogenic alleles including ASXL1 due to dysregulation of the chromatin state in hematopoietic stem and progenitor cells. My long term goals are to understand MDS disease pathogenesis and mechanisms by which MDS transforms to AML and to identify novel targeted therapeutics to treat human MDS. The first specific aim will be to characterize the stem and progenitor cell phenotype following BAP1 hematopoietic-specific loss in a novel mouse model in addition to characterizing the in vivo epigenetic phenotype of BAP1 loss in hematopoiesis. The second specific aim will serve to identify mechanisms by utilizing ASXL1 and EZH2 conditional knockout models and in vitro BAP1 shRNA systems as well as to assess the sensitivity of BAP1 loss-of-function model systems to epigenetic therapies. The implications are that these findings will be relevant in other cancer contexts where BAP1 mutations are quite prevalent, such as uveal melanoma, mesothelioma, and renal cell carcinoma. Further, we will establish novel MDS models for future testing of novel therapeutic agents in subsequent studies.

描述（由申请人提供）： 该项目旨在表征 BRCA1 相关蛋白 1 (BAP1) 在正常和恶性造血中的作用。已发现 BAP1 在人类骨髓增生异常综合征 (MDS) 中发生突变和下调，这与 BAP1 在造血室中作为新型肿瘤抑制因子的功能一致。 BAP1 的作用机制和作用背景仍然很大程度上未知。我们的合作者最近发现，全身条件性缺失 BAP1 的小鼠会出现全血细胞减少症，这是人类 MDS 的一个特征。我们实验室和其他人之前的工作表明，BAP1（一种在组蛋白 H2A 赖氨酸 119 处去泛素化中发挥作用的酶）与 ASXL1 形成三元复合物。 ASXL1 在人类 MDS 和急性髓性白血病 (AML) 中常见突变，ASXL1 突变是患者预后不良的预测因子。我们已经证明，虽然 BAP1 和 ASXL1 确实在造血细胞中相互作用，但这些蛋白对靶基因表达和全局组蛋白调节具有独立的影响。 ASXL1 缺失会导致 HOXA 簇表达上调并降低 Polycomb 抑制复合物 2 (PRC2) 功能，而 BAP1 缺失则会增加整体 H3K27me3 并抑制 HOXA 基因表达。我的中心假设是：(1) 造血特异性区室中 BAP1 的遗传缺失会导致干细胞和/或祖细胞缺陷导致造血异常，(2) BAP1 调节 PRC2 复合体，BAP1 下调的 MDS 患者将对 EZH2 抑制剂敏感，(3) BAP1 可能与其他致癌等位基因协同作用，包括 ASXL1 由于造血干细胞和祖细胞中染色质状态失调所致。我的长期目标是了解 MDS 疾病的发病机制和 MDS 转化为 AML 的机制，并确定治疗人类 MDS 的新型靶向疗法。第一个具体目标是在新型小鼠模型中表征 BAP1 造血特异性丧失后的干细胞和祖细胞表型，以及表征造血中 BAP1 丧失的体内表观遗传表型。第二个具体目标是利用 ASXL1 和 EZH2 条件敲除模型和体外 BAP1 shRNA 系统来确定机制，并评估 BAP1 功能丧失模型系统对表观遗传疗法的敏感性。其含义是，这些发现将与 BAP1 突变相当普遍的其他癌症相关，例如葡萄膜黑色素瘤、间皮瘤和肾细胞癌。此外，我们将建立新的MDS模型，以便在后续研究中测试新的治疗药物。