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是淋巴细胞生成的主要调节者，并设定T细胞活化的阈值。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同种型，其抑制全长Ikaros DNA结合。Ikaros DNA结合能力的降低可能会下调能够调节T细胞增殖的基因子集。最近，我们证明了VPACR-1的基因，一种在幼稚CD 4 T细胞上表达的G蛋白偶联的抗增殖受体，是Ikaros的新基因靶点。通过抗增殖性VPACR-1受体的信号传导可以天然地阻碍CD 4 T细胞中的细胞周期进入。因此，在淋巴细胞白血病的某些病因中，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如何在幼稚和活化的CD 4 T细胞中调节VPACR-1可能1。提供对Ikaros的关键下游事件的深入了解，该事件导致造血疾病中不受控制的增殖，以及2.）导致了解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（包括胃肠道系统）中的旁观者T细胞活化。因此，本研究的目的是1）。证实Ikaros对初级幼稚和活化的CD 4 T淋巴细胞中VPACR-1表达的双向作用，2.）证明哪些PKC途径信号传导蛋白介导TCR依赖性VPACR-1下调，以及3.）鉴定在T细胞活化期间介导IK募集到异染色质IK磷酸受体残基

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