REGULATION OF MYELIN BASIC PROTEIN GENE EXPRESSION

髓鞘碱性蛋白（MBP）基因的MBI调控序列 相对于所述核苷酸序列，跨越核苷酸-14至-50之间。 转录起始位点对于细胞类型特异性转录至关重要 编码髓鞘主要蛋白成分的MBP基因 中枢神经系统（CNS）的鞘。 我们最近的研究 表明MB 1序列与发育控制的 来自小鼠脑的DNA结合蛋白，命名为MEF-1/Pur alpha。 MEF- 1/Pur α在体外增加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/Pur alpha展品 与JCV早期蛋白、T抗原的结合能力。 过表达 少突胶质细胞系中的JCV T抗原废除转录 通过MEF-1/Pur α激活MBP启动子。 JCV是人类 嗜神经病毒，其在CNS中复制时诱导 由于少突胶质细胞的溶解性破坏导致脱髓鞘。 在 此外，转基因动物的结果表明， 缺乏完整的病毒基因组，JCV-T抗原的表达， 少突胶质细胞引起CNS的髓鞘形成障碍。 生化研究 已经表明髓磷脂基因水平的显著降低 这些动物的表情。 因此，我们假设， JCV T-抗原与MEF-1/Pur α的结合可使MEF-1功能性失活。 1/Pur α并导致MBP和其他髓鞘的异常表达 实验动物的基因。 蛋白质-蛋白质研究结果 已经表明MEF-1/Pur α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降低了 MBP基因转录，提示p107可能代表了细胞内 JCV T抗原的同源物，其可以调节MEF的活性， 1/Pur α转录因子在脑发育过程中的作用。 评价 我们的假设，我们计划：I）确定MEF-1/Pur α的水平 基因表达及其与MBP的MB 1基序的关系 转基因小鼠在大脑发育过程中; ii）检查 转基因小鼠和对照中的MEF-1/Pur α和JCV T抗原 在大脑发育的不同阶段的同窝仔; iii）鉴定蛋白质 T-抗原需要结合和抑制的区域 MEF-1/Pur α的转录功能; iv）确定MEF-1/Pur α的转录功能。 持续表达T抗原以获得MEF的要求- 1/Pur α并诱导CNS的髓鞘形成不足;和v）研究 p107通过MEF调节MBP基因转录的潜力- 1/Pur α途径，并确定和表征其他潜在的 细胞蛋白，其在与MEF-1/Pur α相互作用后， 大脑发育过程中的活动。 JCV T-抗原在一种 转基因小鼠模型提供了一个极好的机会， 髓磷脂基因调控机制 在正常和疾病状态下表达。

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.