HETEROCHROMATIN RECRUITMENT OF THE VPAC1 LOCUS BY IKAROS

描述(由申请人提供)： 本研究的重点是探讨Ikaros介导的T淋巴细胞血管活性肠肽受体-1(VPACR-1)转录调控的分子机制。Ikaros是淋巴生成的主要调节者，并为T细胞激活设定阈值。Ikaros突变的小鼠模型发展为侵袭性淋巴细胞白血病，发病率为100%。一些人类白血病表达突变的显性阴性Ikaros亚型，抑制全长Ikaros DNA结合。Ikaros DNA结合能力的下降可能会下调一组能够调节T细胞增殖的基因。最近，我们证明了VPACR-1基因是Ikaros的一个新的基因靶点。VPACR-1是一种表达于天然CD4T细胞上的G蛋白偶联的抗增殖受体。通过抗增殖的VPACR-1受体发出的信号可能会自然地阻碍CD4T细胞进入细胞周期。因此，在某些淋巴母细胞白血病的病因中，Ikaros蛋白和/或DNA结合能力的降低可能下调VPACR-1，并导致不受控制的增殖。了解Ikaros如何调节NA和激活的CD4T细胞中的VPACR-1可能有1。)提供对Ikaros的一个关键下游事件的洞察，该事件导致造血疾病的不受控制的增殖和2。了解Ikaros介导的VPACR-1调节在正常免疫功能中的作用，例如抑制某些器官中旁观者T细胞的激活，包括胃肠道系统。因此，本研究的目的是：1)证实Ikaros对原代和活化的CD4T淋巴细胞VPACR-1表达的双向影响，2.)说明哪些PKC途径信号蛋白介导TCR依赖的VPACR-1下调，以及3.确定在T细胞激活过程中介导IK向异染色质募集的IK磷受体残基

DESCRIPTION (provided by applicant): The focus of this proposal is to investigate the molecular mechanisms governing Ikaros-mediated transcriptional regulation of vasoactive intestinal peptide receptor - 1 (VPACR-1) in T lymphocytes. Ikaros is a master regulator of lymphopoiesis and sets the threshold for T cell activation. Ikaros mutated mouse models develop an aggressive lymphoblastic leukemia with 100% incidence. Some human leukemias express mutated dominant negative Ikaros isoforms that inhibit full-length Ikaros DNA binding. Decreases in Ikaros DNA binding capacity may downregulate a subset of genes capable of regulating T cell proliferation. Recently, we demonstrated that the gene for VPACR-1, a G protein coupled, antiproliferative receptor expressed on na¿ve CD4 T cells, is a novel gene target for Ikaros. Signaling through the anti-proliferative VPACR-1 receptor may naturally impede cell cycle entry in CD4 T cells. Therefore, a decrease in Ikaros protein and/or DNA binding capacity, during certain etiologies of lymphoblastic leukemia, may downregulate VPACR-1 and contribute to uncontrolled proliferation. Understanding how Ikaros regulates VPACR-1 in na¿ve and activated CD4T cells may 1.) provide insight into a crucial downstream event from Ikaros that contributes to uncontrolled proliferation in hematopoietic disorders and 2.) lead to an understanding of the role Ikaros-mediated regulation of VPACR-1 plays in normal immune function, such as suppressing bystander T cell activation in certain organs including the gastrointestinal system. Therefore, the aims of this research are to 1.) confirm bi-directional effects of Ikaros on VPACR-1 expression in primary na¿ve and activated CD4 T lymphocytes, 2.) demonstrate which PKC pathway signaling proteins mediate TCR-dependent VPACR-1 downregulation, and 3.) identify IK phosphoacceptor residues that mediate IK recruitment to heterochromatin during T cell activation