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（由申请人提供）：锌指基因在白血病发生中的作用：拟议研究的目的是通过鉴定 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 对于正常造血和 T 细胞分化至关重要，并充当肿瘤抑制剂。 Ikaros 基因交替剪接产生多种锌指蛋白，参与基因调控和染色质重塑。我们的初步数据表明：1) Ikaros 在细胞周期的 G1 和 S 期被 CK2 和其他激酶在多个进化保守位点磷酸化。 2) Ikaros 在特定氨基酸处的磷酸化调节其 DNA 结合能力和亚细胞定位。 3) Ikaros 在体内与 Bcl-xL 基因启动子结合，Ikaros 活性的失调与 Bcl-xL 基因表达的上调相关。我们提案的具体目标是： 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展调节剂的功能来促进 Ikaros 的肿瘤抑制活性。我们假设 Ikaros 的磷酸化会干扰其转录调节和染色质重塑的功能并影响细胞增殖。我们将定义 CK2 靶位点 Ikaros 磷酸化在 Ikaros 靶基因染色质重塑中的作用。将在体内研究 Ikaros 磷酸化在调节 T 细胞分化和 T 细胞增殖中的作用。来自靶向破坏 Ikaros 的小鼠的鼠干细胞将被含有野生型 Ikaros 或拟磷 Ikaros 突变体的逆转录病毒载体感染，并移植到亚致死照射的 Ikaros 基因敲除小鼠中。将拟磷化 Ikaros 突变体恢复正常 T 细胞分化的能力与野生型 Ikaros 进行比较。具体目标#2：剖析 CK2-Ikaros 介导的 Bcl-xL 表达调节机制及其对 Ikaros 肿瘤抑制因子功能的贡献。先前的研究表明 Ikaros 抑制 Bcl-xL 基因表达。我们假设 Ikaros 对 Bcl-xL 转录的负调控有助于 Ikaros 作为肿瘤抑制因子的功能。将研究 CK2 激酶介导的 Ikaros 磷酸化在 Bcl-xL 转录调节中的作用。我们将使用靶向破坏 Ikaros 的小鼠作为模型，测试 Bcl-xL 的组成型表达是否干扰 Ikaros 的体内肿瘤抑制。这些研究将对控制 Ikaros 肿瘤抑制功能的信号转导途径进行首次详细的功能分析。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，并将深入了解白血病的病理生理学和治疗。公共健康相关性：拟议研究的目的是了解正常血液形成和免疫系统发育的机制，以及导致白血病发展的变化。该项目的目标是确定 Ikaros 基因的功能。 Ikaros 的正常功能对于正常的血液形成和免疫系统发育至关重要。 Ikaros 基因活性的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正常血液形成和白血病发展的机制。进一步阐明恶性转化过程的机制将有助于为白血病/淋巴瘤患者提供新颖且更有效的治疗选择。