Ubiquitin-Proteolytic Control of HOXA9 in Leukemogenesis

HOXA9 在白血病发生中的泛素蛋白水解控制

• 批准号: 7016787
• 负责人: Pengbo Zhou
• 金额: $ 31.62万
• 依托单位: WEILL MEDICAL COLL OF CORNELL UNIV
• 依托单位国家: 美国
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-01-27 至 2010-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7016787
• 关键词: acute myelogenous leukemia; bone marrow; carcinogenesis; hematopoiesis; leukemia; model; mutant; protein degradation; proteins; ubiquitin

DESCRIPTION (provided by applicant): The HOX homeodomain (HD) proteins are key regulators of hematopoiesis. Aberrant expression or chromosomal translocations involving certain HOX proteins, such as HOXA9, have been implicated in the pathogenesis of acute myeloid leukemia (AML). Our understanding of how the intracellular levels and activities of the HOX proteins are controlled during hematopoiesis is current limited to transcriptional regulation and signal transduction. Little is known about the posttranslational control mechanisms that govern the abundance of the HOX hematopoietic regulators and the functional significance for such regulations. The long-term goal of this study is to understand how ubiquitin-dependent protein degradation regulates normal and malignant hematopoiesis. The central hypothesis of the application is that the cullin 4A (CUL-4A) ubiquitin-ligase controls hematopoietic development through targeted degradation of key hematopoietic regulators. The hypothesis has been formulated on the basis of strong preliminary data, which demonstrated that CUL-4A targets HOXA9 for degradation, and regulates myeloid differentiation and maturation. Hematopoietic-specific knockout of the CUL-4A gene in mice led to an increased expansion of bone marrow progenitor cells and peripheral blood leukocytes. This proposal seeks to determine the biochemical mechanisms underlying the CUL-4A-dependent proteolytic control of HOXA9 and the chromosomal translocation-derived NUP98-HOXA9 fusion, and to elucidate the functional significance of CUL-4A in suppressing leukemic transformation. We are uniquely prepared to undertake the proposed research, since we have recently generated a CUL-4A-resistant HOXA9 mutant, and developed conditional CUL-4A knockout mice and CUL-4A siRNA to eliminate or modulate CUL-4A activity. We have also optimized lentiviral- and retroviral-based gene delivery systems for efficient transduction in primary hematopoietic stem and progenitor cells. We propose to combine the biochemical and molecular genetic approaches in Dr. Pengbo Zhou's lab and the expertise in ex vivo and in vivo hematopoietic analysis in Dr. Malcolm Moore's lab to address the following specific aims: (1) to define the biochemical mechanisms underlying CUL-4A-dependent ubiquitination and degradation of HOXA9. (2) to elucidate the functional significance of HOXA9 degradation by CUL-4A in the pathogenesis of AML. (3) to determine the molecular basis for CUL-4A resistance by the leukemogenic NUP98-HOXA9 fusion and to assess the impact of CUL-4A ablation in the mouse model of NUP98- HOXA9-induced leukemia. Since little information is available regarding the roles of protein degradation during leukemogenesis, successful completion of this proposal will represent a significant advance in understanding a novel posttranslational mechanism that governs the functions of key hematopoietic regulators, and provide a framework for future investigations of targeted protein degradation in normal and malignant hematopoiesis.

描述（由申请人提供）：HOX同源结构域（HD）蛋白是造血的关键调节因子。涉及某些 HOX 蛋白（例如 HOXA9）的异常表达或染色体易位与急性髓系白血病 (AML) 的发病机制有关。目前，我们对造血过程中 HOX 蛋白的细胞内水平和活性如何控制的理解仅限于转录调控和信号转导。关于控制 HOX 造血调节因子丰度的翻译后控制机制以及此类调节的功能意义，人们知之甚少。这项研究的长期目标是了解泛素依赖性蛋白质降解如何调节正常和恶性造血。该应用的中心假设是 cullin 4A (CUL-4A) 泛素连接酶通过关键造血调节因子的靶向降解来控制造血发育。该假设是在强有力的初步数据的基础上提出的，这些数据证明 CUL-4A 以 HOXA9 为目标进行降解，并调节骨髓分化和成熟。小鼠造血特异性 CUL-4A 基因敲除导致骨髓祖细胞和外周血白细胞的扩增增加。该提案旨在确定 HOXA9 的 CUL-4A 依赖性蛋白水解控制和染色体易位衍生的 NUP98-HOXA9 融合的生化机制，并阐明 CUL-4A 在抑制白血病转化中的功能意义。我们为开展拟议的研究做好了独特的准备，因为我们最近生成了 CUL-4A 抗性 HOXA9 突变体，并开发了条件性 CUL-4A 敲除小鼠和 CUL-4A siRNA 以消除或调节 CUL-4A 活性。我们还优化了基于慢病毒和逆转录病毒的基因传递系统，以便在原代造血干细胞和祖细胞中进行有效转导。我们建议将周鹏波博士实验室的生化和分子遗传学方法与Malcolm Moore博士实验室的离体和体内造血分析专业知识相结合，以实现以下具体目标：（1）定义CUL的生化机制HOXA9 的 -4A 依赖性泛素化和降解。 (2)阐明CUL-4A降解HOXA9在AML发病机制中的功能意义。 (3)确定致白血病NUP98-HOXA9融合对CUL-4A抵抗的分子基础，并评估CUL-4A消融对NUP98-HOXA9诱导的白血病小鼠模型的影响。由于关于白血病发生过程中蛋白质降解作用的信息很少，因此该提案的成功完成将代表着在理解控制关键造血调节因子功能的新型翻译后机制方面取得了重大进展，并为未来研究靶向蛋白质降解提供了框架在正常和恶性造血过程中。