The Role of Zinc Finger Genes in Leukemogenesis

锌指基因在白血病发生中的作用

• 批准号: 8231832
• 负责人: Sinisa Dovat
• 金额: $ 30.12万
• 依托单位: PENNSYLVANIA STATE UNIV HERSHEY MED CTR
• 依托单位国家: 美国
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-07-01 至 2011-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8231832
• 关键词: Role; Zinc; Finger; Genes; Leukemogenesis

DESCRIPTION (provided by applicant): The Role of Zinc Finger Genes in Leukemogenesis: The objective of the proposed study is to understand normal hematopoiesis and the malignant transformation of hematopoietic cells by identifying the biological functions of Ikaros proteins. Ikaros is essential for normal hematopoiesis and T cell differentiation and acts as a tumor suppressor. The Ikaros gene is alternately spliced to generate multiple zinc finger proteins involved in gene regulation and chromatin remodeling. Our preliminary data show that: 1) Ikaros is phosphorylated at multiple evolutionarily conserved sites by CK2 and other kinases during G1 and S phase of the cell cycle 2) Phosphorylation of Ikaros at specific amino acids regulates its DNA-binding ability and subcellular localization. 3) Ikaros binds to the Bcl-xL gene promoter in vivo and disregulation of Ikaros activity is associated with upregulation of Bcl-xL gene expression. The specific aims of our proposals are: Specific Aim #1: Determine how site-specific CK2-mediated phosphorylation contributes to Ikaros' tumor suppressor activity by controlling its function as a regulator of differentiation and cell cycle progression. We hypothesize that phosphorylation of Ikaros interferes with its function in transcriptional regulation and chromatin remodeling and influences cellular proliferation. We will define the role of Ikaros phosphorylation at CK2 target sites in the chromatin remodeling of Ikaros target genes. The role of Ikaros' phosphorylation in regulating T cell differentiation and T cell proliferation will be studied in vivo. Murine stem cells from mice with targeted disruption of Ikaros will be infected with retroviral vectors containing wild type Ikaros or phosphomimetic Ikaros mutants and transplanted into sublethally irradiated Ikaros knockout mice. The ability of phosphomimetic Ikaros mutants to restore normal T cell differentiation will be compared to that of wild type Ikaros. Specific aim #2: Dissect the mechanism of CK2- Ikaros-mediated regulation of Bcl-xL expression and its contribution to Ikaros function as a tumor suppressor. Previous studies suggest that Ikaros represses Bcl-xL gene expression. We hypothesize that the negative regulation of Bcl-xL transcription by Ikaros contributes to Ikaros' function as a tumor suppressor. The role of CK2 kinase-mediated phosphorylation of Ikaros in regulation of Bcl-xL transcription will be studied. We will test whether constitutive expression of Bcl-xL interferes with Ikaros' tumor suppression in vivo using mice with targeted disruption of Ikaros as a model. These studies will provide the first detailed functional analysis of the signal transduction pathways that control the tumor suppressor function of Ikaros. Our research will provide new and important information on the mechanisms controlling the proliferation of hematopoietic cells and will yield insights into the pathophysiology and treatment of leukemia. PUBLIC HEALTH RELEVANCE: The objective of the proposed study is to understand the mechanism of normal blood formation and immune system development, and changes that lead to development of leukemia. The goal of the proposed project is to identify the function of Ikaros gene. Normal function of Ikaros is essential for normal blood forming and immune system development. Altered activity of the Ikaros gene is associated with the development of childhood acute lymphoblastic leukemia (ALL), infant leukemia and juvenile chronic lymphocytic leukemia. Thus, our results will help to gain insights into the mechanism of normal blood forming and development of leukemia. Further elucidation of the mechanism of the malignant transformation process will aid in providing novel and more effective treatment options for patients with leukemia/lymphoma.

描述(申请人提供)：锌指基因在白血病发生中的作用：建议的研究目的是通过鉴定Ikaros蛋白的生物学功能来了解正常造血和造血细胞的恶性转化。Ikaros对正常的造血和T细胞分化是必不可少的，并且是一种肿瘤抑制因子。Ikaros基因交替剪接，以产生多个参与基因调控和染色质重塑的锌指蛋白。我们的初步数据表明：1)在细胞周期的G1期和S期，Ikaros在进化上保守的多个位置被CK2和其他激酶磷酸化；2)Ikaros在特定的氨基酸上的磷酸化调节其与DNA的结合能力和亚细胞定位。3)Ikaros在体内与Bclxl基因启动子结合，Ikaros活性失调与Bclxl基因表达上调有关。我们建议的具体目标是：具体目标1：确定位点特异性CK2介导的磷酸化如何通过控制Ikaros作为分化和细胞周期进程调节器的功能来促进其肿瘤抑制活性。我们假设Ikaros的磷酸化干扰了它在转录调节和染色质重塑中的功能，并影响细胞增殖。我们将确定CK2靶点的Ikaros磷酸化在Ikaros靶基因染色质重塑中的作用。Ikaros的磷酸化在调节T细胞分化和T细胞增殖中的作用将在体内进行研究。来自靶向破坏Ikaros的小鼠的小鼠干细胞将被含有野生型Ikaros或模仿磷酸盐的Ikaros突变体的逆转录病毒载体感染，并被移植到亚致死辐射的Ikaros基因敲除小鼠体内。拟磷突变株恢复正常T细胞分化的能力将与野生型伊卡洛斯进行比较。具体目的#2：剖析CK2-Ikaros调控Bclxl表达的机制及其对Ikaros抑癌作用的影响。以往的研究表明，Ikaros抑制了Bclxl基因的表达。我们推测，Ikaros对Bclxl转录的负调控可能参与了Ikaros作为肿瘤抑制因子的作用。CK2激酶介导的Ikaros磷酸化在调控Bclxl转录中的作用将被研究。我们将以靶向破坏Ikaros的小鼠为模型，在体内测试Bclxl的结构性表达是否干扰Ikaros的肿瘤抑制。这些研究将首次对控制Ikaros肿瘤抑制功能的信号转导通路进行详细的功能分析。我们的研究将为控制造血细胞增殖的机制提供新的重要信息，并将为白血病的病理生理和治疗提供新的见解。公共卫生相关性：这项拟议研究的目标是了解正常血液形成和免疫系统发育的机制，以及导致白血病发生的变化。拟议项目的目标是确定Ikaros基因的功能。伊卡洛斯的正常功能对正常造血和免疫系统发育至关重要。Ikaros基因活性改变与儿童急性淋巴细胞白血病(ALL)、婴儿白血病和青少年慢性淋巴细胞白血病的发生有关。因此，我们的结果将有助于深入了解白血病正常造血和发展的机制。进一步阐明恶性转化过程的机制将有助于为白血病/淋巴瘤患者提供新的、更有效的治疗选择。