CIITA REGULATION IN B LYMPHOCYTES AND MULTIPLE MYELOMA

描述：(摘自摘要)转录反式激活因子II类反式激活因子(CIITA)是一种“主调节因子”，可激活多种基因的表达，这些基因编码参与MHC II类抗原加工和提呈途径的蛋白质。CIITA基因的失活取消了MHC-II类和这些其他因子的结构性和诱导性表达，这是某些类型的裸淋巴细胞综合征的分子基础。这项建议集中在调节CIITA基因在B系中的表达。CIITA在成熟的B细胞系中表达，但在骨髓瘤中不表达，这似乎是后者缺乏MHC II表达的原因。关于CIITA基因在B细胞和骨髓瘤中的表达是如何调控的，人们知之甚少，这也是这项提案的重点。在目标1中，研究人员建议继续进行研究，其目标是在一个包含主要用于B细胞的启动子的区域中，剖析CIITA基因上游的各种正和负调控元件。这一目标将涉及启动子缺失和定点突变，其位置将由体内足迹研究揭示的转录因子结合相互作用的信息指导。第二个目标是研究CIITA抑制的机制。主调控子PRDI-BF1(Blimp-1)参与了B细胞向浆细胞表型的终末分化，也直接参与了对CIITA基因表达的抑制。赖特博士将使用多种方法研究该转录因子在这一过程中的作用，包括PRDI-BF1的过度表达，该因子的显性负性形式的表达，改变其在CIITA启动子中的结合位置，以及使用反义方法抑制其表达。在最终目标中，研究人员建议使用凝胶漂移分析等方法来表征在B细胞中诱导CIITA转录所需的因素。他还建议使用酵母单杂交系统或噬菌体表达文库的寡核苷酸筛选来克隆和表征其中一个因子。

DESCRIPTION: (Adapted from abstract) The transcriptional transactivator Class II transactivator (CIITA) acts a "master regulator" to activate expression of a variety of genes that encode proteins that participate in the MHC class II antigen processing and presentation pathway. Inactivation of the CIITA gene abolishes constitutive and inducible expression of MHC class II and these other factors, and this is the molecular basis for certain types of the Bare Lymphocyte Syndrome. This proposal concentrates on the regulation of expression of the CIITA gene in the B lineage. CIITA is expressed in mature B cell lines, but is not expressed in myelomas, and this appears to account for the lack of expression of MHC II in the latter. Little is known about how CIITA gene expression is regulated in B cells and myelomas, and this is the focus of this proposal. In Aim 1 the investigator proposes to continue studies whose goal is to dissect the various positive and negative regulatory elements upstream of the CIITA gene, in a region shown to contain the promoter used predominantly in B cells. This Aim will involve promoter deletions and site-specific mutations, the locations of which will be guided by information regarding transcription factor binding interactions revealed by in vivo footprinting studies. In the second Aim the mechanism of CIITA repression will be studied. The master regulator PRDI-BF1 (Blimp-1) is involved in driving terminal differentiation of B cells to plasma cell phenotype, and also appears to be directly involved in the repression of CIITA gene expression. The Dr. Wright will investigate the role of this transcription factor in this process using a variety of approaches, including overexpression of PRDI-BF1, expression of dominant negative forms of this factor, changing the location of its binding site in the CIITA promoter, and inhibition of its expression using anti-sense approaches. In the final Aim, the investigator proposes to characterize the factors required for induction of CIITA transcription in B cells using such approaches such as gel shift assays. He also proposes to clone and characterize one of these factors using the yeast one-hybrid system or oligonucleotide screening of phage expression libraries.