Regulators and Regulation of MHC class II genes

描述(申请人提供)：主要组织相容性复合体II类基因转录受到严格调控，以确保有效的免疫系统活动。这些基因的不适当表达可能导致自身免疫性疾病。了解MHC II转录的分子机制可能会为许多人类疾病创造基于免疫的新疗法。基因特异的转录因子聚集在MHC II启动子上，启动转录。至关重要的是异三聚体调节因子X(RFX)复合体和第二类反式激活蛋白(CUTA)。CIITA和RFX的一个亚基RFXAP都与染色质重塑因子Brahma相关基因-1(BRG1)相互作用。RFXAP-BRG1相互作用是否导致染色质重塑似乎取决于细胞类型。为了解释这一观察结果，假设RFXAPBRG1的MHC II启动子必须存在适当的组蛋白修饰，才能有效地重塑染色质。在具体目标1中，组蛋白修饰和负责这些修饰的酶将在MHC II启动子中进行表征。观察到的修饰将与RFXAP-BRG1和CIITA-BRG1相互作用重塑染色质的能力相关。研究结果将为深入了解控制MHC II转录的细胞类型特异性调控机制提供依据。 在特定目标2中，将鉴定一种新的针对MHC II类基因的转录调节蛋白。最近克隆了一种与CIITA C-末端结合的新蛋白的编码基因。这种锌指蛋白被称为CCB1。CCB1的过度表达导致CIITA对MHC I类和II类基因的过度激活。CCB1很可能与DNA结合，实际上可能与MHC启动子的W-box相互作用。利用生化和遗传技术，CCB1改变MHC II类转录和CIITA活性的方式将被解决。此外，还将探索CCB1在MHC基因以外的基因调控中的更广泛作用。

DESCRIPTION (provided by applicant): Major histocompatibility complex class II gene transcription is tightly regulated, to ensure effective immune system activity. Inappropriate expression of these genes can result in autoimmune disease. Understanding the molecular mechanisms of MHC II transcription may allow the creation of novel immune based therapies for many human diseases. Gene-specific transcription factors assemble at MHC II promoters, to initiate transcription. Of critical importance are the heterotrimeric regulatory factors X (RFX) complex and the class II trans-activator protein (CUTA). CIITA, and one subunit of RFX known as RFXAP, both interact with a chromatin remodeling factor, brahma related gene-1 (BRG1). Whether the RFXAP-BRG1 interaction leads to chromatin remodeling appears to be dependent on cell-type. To explain this observation, it is hypothesized that the appropriate histone modifications must be present at MHC II promoters for RFXAPBRG1 to effectively remodel chromatin. In specific aim 1, histone modifications, and the enzymes responsible for those modifications, will be characterized at MHC II promoters. The observed modifications will be correlated with the ability of RFXAP-BRG1 and CIITA-BRG1 interactions to remodel chromatin. Results will provide insight into cell-type specific regulatory mechanisms controlling MHC II transcription. In the specific aim 2, a new transcriptional regulatory protein for MHC class II genes will be characterized. A cDNA that codes for a novel protein that binds the C-terminus of CIITA was recently cloned. This zinc finger protein is called CCB1. Over-expression of CCB1 results in super-activation of MHC class I and class II genes by CIITA. It is likely that CCB1 binds DNA, and may in fact interact with the W-box of MHC promoters. Employing biochemical and genetic techniques, the manner in which CCB1 alters MHC class II transcription, and CIITA activity, will be addressed. In addition, a broader role for CCB1 in gene regulation, beyond MHC genes, will be explored.