The Role of Zinc Finger Genes in Cellular Proliferation

描述（申请人提供）：本研究的目的是通过研究Ikaros和Helios两个基因的生物学功能，了解造血细胞的正常造血和恶性转化。Ikaros编码一种参与遗传基因沉默的锌指蛋白。基因破坏实验表明，Ikaros的表达是B和T细胞发育所必需的，并表明Ikaros可以作为肿瘤抑制因子。Helios编码的蛋白质在结构上与Ikaros相似，仅在T细胞中表达。Helios的生物学功能尚不清楚。 研究目标1：研究Ikaros影响细胞增殖和分化的分子机制。我们将鉴定这种蛋白质中组成性磷酸化的氨基酸。将进行拟磷酸化实验以研究特定氨基酸的磷酸化状态如何影响Ikaros功能。我们将研究过表达特定的拟磷酸化Ikaros突变体如何影响细胞增殖。研究目标#2：确定Ikaros蛋白在进化上保守的连接序列磷酸化的功能意义。我们将试图确定磷酸化这个保守的连接蛋白的激酶，并研究所涉及的途径。研究目标#3：确定Helios在人类恶性肿瘤中的作用。我们的初步数据表明，Helios在B细胞中的表达有助于小鼠和人类的恶性转化。将研究Helios如何促进恶性转化的分子机制。我们将确定Helios在人类恶性肿瘤中表达的发生率和意义，并确定Helios影响人类B细胞发育的分子机制。这些研究将提供重要的信息机制控制造血细胞的发展和增殖，并将产生深入了解白血病的病理生理和治疗。

DESCRIPTION (provided by applicant): The objective of the present study is to understand the normal hematopoiesis and malignant transformation of hematopoietic cells by studying biological functions of two genes, Ikaros and Helios. Ikaros encodes a zinc finger protein involved in heritable gene silencing. Gene disruption experiments have shown that expression of Ikaros is necessary for the development of both B and T cells and suggested that Ikaros can act as a tumor suppressor. Helios encodes a protein that is structurally similar to Ikaros and is only expressed in T cells. The biological function of Helios is unknown. The aims of this proposal are: Research Aim #1: Study the molecular mechanisms by which Ikaros affects cellular proliferation and differentiation. We will identify the constitutively phosphorylated amino acids in this protein. Phosphomimetic experiments will be performed to study how the phosphorylation status of particular amino acid(s) affects Ikaros function. We will study how overexpressing particular phosphomimetic Ikaros mutants affects cellular proliferation. Research Aim #2: Determine the functional significance of the phosphorylation of Ikaros protein at an evolutionarily conserved linker sequence. We will try to identify the kinase that phosphorylates this conserved linker and study the pathway involved. Research Aim #3: Determine the role of Helios in human malignancies. Our preliminary data suggest that expression of Helios in B cells contributes to malignant transformation in mouse and human. The molecular mechanism of how Helios promotes malignant transformation will be studied. We will establish the incidence and significance of Helios expression in human malignancies and determine the molecular mechanisms by which Helios affects B cell development in humans. These studies will provide important information on the mechanisms controlling development and proliferation of hematopoietic cells and will yield insights into the pathophysiology and treatment of leukemia.