REGULATION OF MYELIN BASIC PROTEIN GENE EXPRESSION

髓鞘碱性蛋白(MBP)基因的MBI调控序列 在核苷酸-14到-50之间的跨度 转录起始点是细胞类型特异性转录的关键 编码髓鞘主要蛋白质组分的MBP基因 中枢神经系统(CNS)中的鞘。我们最近的研究表明 表明MB1序列与发育受控的 从小鼠脑中提取的DNA结合蛋白命名为MEF-1/PURα。MEF- 1/PURα在体外增强MBP的启动子活性 转录系统，并具有刺激转录的能力 少突胶质细胞系中的MBP基因。MEF-1/PURα展示 与JCV早期蛋白、T抗原结合的能力。过度表达 少突胶质细胞系中JCVT抗原抑制转录 MEF-1/PURα激活MBP启动子。JCV是一个人类 嗜神经性病毒在中枢神经系统复制时诱导 少突胶质细胞溶解破坏所致的脱髓鞘。在……里面 此外，转基因动物的结果表明，在 病毒全基因组缺失，JCV-T抗原表达 少突胶质细胞导致中枢神经系统髓鞘功能障碍。生化研究 已经表明髓鞘基因的水平大幅下降 在这些动物身上的表达。因此，我们假设这种关联 JCVT抗原与MEF-1/PURα功能失活MEF-1 1/purα，并导致MBP和其他髓鞘的异常表达 实验动物的基因。蛋白质-蛋白质研究的结果 已经表明MEF-1/PURα与细胞蛋白相互作用 P107，属于视网膜母细胞瘤肿瘤抑制基因家族。 P107在少突胶质细胞中的过表达可降低 MBP基因转录，提示p107可能代表细胞 JCV T抗原的同源物，它可能调节MEF- 1/Purα转录因子在脑发育过程中的作用。评估 我们的假设是，我们计划：i)确定MEF-1/PURα的水平 MBP基因表达及其与MB1基序的关系 大脑发育过程中的转基因小鼠；ii)检查 转基因小鼠和对照小鼠的MEF-1/PURα和JCVT抗原 在大脑发育的不同阶段产仔；iii)识别蛋白质 T抗原需要结合和失活的区域 MEF-1/PURα的转录功能；iv)决定 T抗原持续表达对MEF-1灭活的要求 1/purα并诱导中枢神经系统髓鞘减退；以及v)研究 P107通过MEF-1调控MBP基因转录的研究 1/PURα途径，并确定和表征其他潜在的 细胞蛋白在与MEF-1/PURα相互作用时修饰 它在大脑发育过程中的活动。JCVT抗原在非霍奇金淋巴瘤中的应用 转基因小鼠模型提供了一个很好的破译机会 髓鞘基因调控的调控机制 在正常和疾病状态下的表达。

The MBI regulatory sequence of the myelin basic protein (MBP) gene spanning between nucleotides -14 to -50 with respect to the transcription start site is critical for cell type-specific transcription of the MBP gene which encodes the major protein component of the myelin sheath in the central nervous system (CNS). Our recent studies have indicated that the MB1 sequence binds to a developmentally controlled DNA-binding protein from mouse brain named MEF-1/Pur alpha. MEF- 1/Pur alpha increases the promoter activity of MBP in an in vitro transcription system and has the ability to stimulate transcription of the MBP gene in oligodendrocytic cell lines. MEF-1/Pur alpha exhibits binding ability to the JCV early protein, T-antigen. Overexpression of JCV T-antigen in oligodendrocytic cell lines abrogates transcriptional activation of the MBP promoter by MEF-1/Pur alpha. JCV is a human neurotropic virus which upon replication in the CNS induces demyelination due to the lytic destruction of oligodendrocytes. In addition, results from transgenic animals have indicated that, in the absence of the entire viral genome, expression of JCV-T antigen in oligodendrocytes causes dysmyelination of the CNS. Biochemical studies have indicated a substantial decrease in the level of myelin gene expression in these animals. Thus, we hypothesize that the association of JCV T-antigen with MEF-1/Pur alpha functionally inactivates MEF- 1/Pur alpha and results in aberrant expression of MBP and other myelin genes in experimental animals. Results from protein-protein studies have indicated that MEF-1/Pur alpha interacts with the cellular protein p107, which belongs to the retinoblastoma tumor suppressor gene family. Overexpression of p107 in oligodendrocytic cells decreases the level of MBP gene transcription, suggesting that p107 may represent the cellular homologue for JCV T-antigen, which may modulate activity of the MEF- 1/Pur alpha transcription factor during brain development. To evaluate our hypothesis, we plan to: I) determine the level of MEF-1/Pur alpha gene expression and its association with the MB1 motif of MBP in transgenic mice during brain development; ii) examine the association of MEF-1/Pur alpha and JCV T-antigen in transgenic mice and control littermates at various stages of brain development; iii) identify protein regions which are required by T-antigen to associate with and inactivate the transcriptional function of MEF-1/Pur alpha; iv) determine the requirements for continual expression of T-antigen to inactivate of MEF- 1/Pur alpha and induce hypomyelination of CNS; and v) investigate the potential of p107 in modulating MBP gene transcription through MEF- 1/Pur alpha pathway and identify and characterize other potential cellular proteins, which upon interaction with MEF-1/Pur alpha, modify its activity during brain development. The use of JCV T-antigen in a transgenic mouse model provides an excellent opportunity to decipher the regulatory mechanisms involved in the control of myelin gene expression in normal and disease states.