CIITA REGULATION IN B LYMPHOCYTES AND MULTIPLE MYELOMA

描述：（改编自摘要）转录反激活因子II类反激活因子（CIITA）作为“主调节剂”激活多种基因的表达，这些基因编码参与MHC II类抗原加工和递呈途径的蛋白质。CIITA基因的失活消除了MHC II类和这些其他因子的组成和诱导表达，这是某些类型裸淋巴细胞综合征的分子基础。本文主要研究CIITA基因在B系中的表达调控。CIITA在成熟的B细胞系中表达，但在骨髓瘤中不表达，这似乎解释了后者缺乏MHC II表达的原因。CIITA基因在B细胞和骨髓瘤中的表达调控机制尚不清楚，这也是本研究的重点。在Aim 1中，研究者建议继续研究，其目标是剖析CIITA基因上游的各种正调控元件和负调控元件，该区域显示包含主要在B细胞中使用的启动子。该目标将涉及启动子缺失和位点特异性突变，其位置将由体内足迹研究揭示的转录因子结合相互作用信息指导。第二部分将研究CIITA抑制的机制。主调控因子PRDI-BF1 （Blimp-1）参与驱动B细胞向浆细胞表型的终端分化，也可能直接参与抑制CIITA基因的表达。Wright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的过表达，该因子的显性阴性形式的表达，改变其在CIITA启动子中的结合位点的位置，以及使用反义方法抑制其表达。在最后的目标中，研究者建议使用凝胶转移法等方法来表征诱导B细胞中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克隆和表征这些因子之一。

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.