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: 7173460
• 负责人: Pengbo Zhou
• 金额: $ 29.06万
• 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/7173460
• 关键词: Ablation; Acute Myelocytic Leukemia; Address; Affect; Binding; Biochemical; Bone Marrow; Bone Marrow Cells; Chromosomal translocation; Complex; DNA; Data; Development; Future; Genes; Goals; HOX protein; HOXA9 gene; HOXA9 protein; Hematopoiesis; Hematopoietic; Hematopoietic stem cells; Homeodomain Proteins; In Vitro; Incidence; Investigation; Knock-out; Knockout Mice; Leukocytes; Malignant - descriptor; Maps; Mediating; Molecular; Molecular Genetics; Mus; Myelogenous; NUP98 gene; Oncogenic; Pathogenesis; Patients; Play; Proteins; Proteolysis; Regulation; Research; Research Personnel; Resistance; Role; Signal Transduction; Site-Directed Mutagenesis; Small Interfering RNA; Stem cells; Structure; System; Testing; Transcriptional Regulation; Transplantation; Ubiquitin; Ubiquitination; Yeasts; base; cullin 4A; gene delivery system; homeodomain; in vivo; leukemia; leukemogenesis; mouse model; mutant; novel; nuclear pore complex protein 98; peripheral blood; positional cloning; programs; protein degradation; receptor; stem; tool; ubiquitin ligase; yeast two hybrid system

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同源域（HD）蛋白是造血的关键调节因子。涉及某些HOX蛋白（如HOXA 9）的异常表达或染色体易位与急性髓性白血病（AML）的发病机制有关。我们对细胞内HOX蛋白的水平和活性在造血过程中是如何控制的理解目前仅限于转录调控和信号转导。很少有人知道的翻译后控制机制，管理丰富的HOX造血调节和功能的意义，这样的规定。这项研究的长期目标是了解泛素依赖的蛋白质降解如何调节正常和恶性造血。本申请的中心假设是cullin 4A（CUL-4A）泛素连接酶通过靶向降解关键造血调节因子来控制造血发育。该假设是基于强有力的初步数据制定的，这些数据表明CUL-4A靶向HOXA 9降解，并调节骨髓分化和成熟。造血特异性敲除小鼠中的CUL-4A基因导致骨髓祖细胞和外周血白细胞的扩增增加。该建议旨在确定HOXA 9的CUL-4A依赖性蛋白水解控制和染色体易位衍生的NUP 98-HOXA 9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了独特的准备，因为我们最近产生了CUL-4A抗性HOXA 9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递送系统，用于在原代造血干细胞和祖细胞中进行有效转导。我们建议联合收割机结合周鹏波博士实验室的生物化学和分子遗传学方法以及Malcolm摩尔博士实验室在离体和体内造血分析方面的专业知识，以解决以下具体目标：（1）确定HOXA 9的CUL-4A依赖性泛素化和降解的生化机制。(2)阐明H 0XA 9被CUL-4A降解在AML发病机制中的功能意义。(3)通过致白血病NUP 98-HOXA 9融合确定CUL-4A抗性的分子基础，并评估NUP 98-HOXA 9诱导的白血病小鼠模型中CUL-4A消融的影响。由于很少有信息是关于蛋白质降解的作用在白血病发生，成功完成这一建议将代表一个重大的进步，了解一种新的翻译后机制，管理的关键造血调节功能，并提供了一个框架，为未来的调查目标蛋白质降解在正常和恶性造血。