HETEROCHROMATIN RECRUITMENT OF THE VPAC1 LOCUS BY IKAROS

本提案的重点是研究Ikaros介导的 T淋巴细胞中血管活性肠肽受体-1（VPACR-1）的转录调节。 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。伊卡洛斯变异了 小鼠模型发展为侵袭性淋巴母细胞白血病，发病率为100%。一些人类 白血病表达抑制全长Ikaros DNA结合的突变显性负性Ikaros同种型。 Ikaros DNA结合能力的降低可能会下调一个能够调节T细胞的基因亚群， 细胞增殖最近，我们证明了VPACR-1基因，一种G蛋白偶联的，抗- 增殖性受体表达于未经处理的CD 4 T细胞上，是Ikaros的新基因靶点。信令通过 抗增殖性VPACR-1受体可以天然地阻碍CD 4 T细胞中的细胞周期进入。因此，我们认为， 在某些淋巴母细胞疾病的病因过程中，Ikaros蛋白和/或DNA结合能力降低 白血病，可能下调VPACR-1，并有助于不受控制的增殖。了解如何 Ikaros可调节幼稚和活化的CD 4 T细胞中的VPACR-1。提供了一个关键的洞察力， Ikaros的下游事件，导致造血系统疾病中不受控制的增殖 和2.）了解Ikaros介导的VPACR-1调节在正常人中的作用， 免疫功能，如抑制某些器官中的旁观者T细胞活化，包括 胃肠系统因此，本研究的目的是1）。确认双向效应 Ikaros对原代幼稚和活化的CD 4 T淋巴细胞中VPACR-1表达的影响，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细胞过程中介导IK募集至异染色质IK磷酸受体残基 activation.

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, anti- proliferative receptor expressed on nah'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'fve 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 naive 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.