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同源域（HD）蛋白是造血的关键调节剂。涉及某些HOX蛋白（例如Hoxa9）的异常表达或染色体易位已与急性髓样白血病（AML）的发病机理有关。我们对造血期间HOX蛋白的细胞内水平和活性的理解限于转录调控和信号转导。关于控制HOX造血调节剂的丰度和此类法规的功能意义的翻译后控制机制知之甚少。这项研究的长期目标是了解泛素依赖性蛋白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 - 岩性酶通过针对关键造血调节剂的靶向降解来控制造血发育。该假设是基于强大的初步数据提出的，该数据表明CUL-4A靶向HOXA9用于降解，并调节髓样分化和成熟。小鼠CUL-4A基因的造血特异性敲除导致骨髓祖细胞和外周血白细胞的扩张增加。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。我们已经准备好进行拟议的研究，因为我们最近产生了耐CUL-4A的HOXA9突变体，并开发了有条件的CUL-4A敲除小鼠和CUL-4A siRNA来消除或调节CUL-4A活性。我们还优化了慢病毒和逆转录病毒的基因递送系统，以有效地转导原代造血干细胞和祖细胞。我们建议在Pengbo Zhou的实验室中结合生化和分子遗传学方法，以及在Malcolm Moore博士实验室中的体内和体内造血分析的专业知识，以解决以下具体目的：（1）以定义CUL-4A Aa Apentination ubiquiquiquiquiquiquiquiquiquiquiquiquiquiquittion和DegrAD的生物化学机制，以供hox依靠和Degrad ubiquitition in tegrad。 （2）阐明了CUL-4A在AML发病机理中hoxa9降解的功能显着性。 （3）确定白血病NUP98-HOXA9融合的CUL-4A耐药性的分子基础，并评估CUL-4A消融在NUP98-HOXA9诱导的白血病小鼠模型中的影响。由于几乎没有关于蛋白质降解在白血病发生过程中的作用的信息，因此成功完成该提案将代表理解一种新型翻译后机制的重大进步，该机制控制着关键的造血调节剂的功能，并为未来对靶向蛋白质降解的框架提供了一个正常和恶性血液中靶向蛋白质的框架。