Activation of Plp gene expression in oligodendrocytes

描述(申请人提供)：髓鞘是由中枢神经系统中的少突胶质细胞产生的，它在沿着轴突传播动作电位中的作用已经得到了很好的研究。髓鞘是神经胶质细胞质膜的延伸，但它在生物化学上是非常不同的。这种差异的一部分可以归因于特定针对髓鞘膜的蛋白质的组成。在这些蛋白质中，髓鞘蛋白脂蛋白(PLP)几乎占成人中枢神经系统髓鞘总蛋白的50%。该基因的表达受到严格的调控。在人类中，P/p基因(位于X染色体上)的突变已被证明与X连锁髓鞘障碍Pelizaeus-Merzbacher病(PMD)和某些类型的痉挛截瘫(SPG-2)有关。髓鞘功能障碍可由P/P基因表达水平升高或缺乏表达引起。因此，准确表达P/P是至关重要的，阐明P/P的调控将有助于破译某些PMD/SPG-2患者可能突变的必要转录调控元件。另一方面，阐明该基因的调控机制可以提供对PMD/SPG-2的替代原因的洞察，这些原因不是由P/P基因突变引起的。 此外，为了帮助促进脱髓鞘疾病患者的重新髓鞘形成过程，了解Gone是如何被调控的是很重要的。多发性硬化症是最常见的脱髓鞘疾病，通常发生在成人，基本上在中枢神经系统发育的活跃髓鞘时期结束后。缺失-转染分析已经证实了位于第一内含子内的调控序列的重要性，它对于调控P/p Gone的表达是必不可少的。其中一个因素，即所谓的ASE，即抗沉默/增强子，似乎在中枢神经系统发育的髓鞘形成期间(以及之后)引起P/p基因表达的显著增加。我们认为，多种因子聚集在ASE上，形成一种立体特异的核蛋白结构，称为“增强体”。为了了解ASE如何介导P/p Gone的激活，人们提出了以下具体目标：1)进一步鉴定ASE，这是位于内含子1 DNA中的一个正的顺式作用调节元件，促进少突胶质细胞中P/p基因的高水平表达；2)确定在ASE上形成转录调节复合体的核因素；3)阐明ASE核蛋白复合体激活少突胶质细胞P/p Gone表达的机制。

DESCRIPTION (provided by applicant): Myelin is produced by oligodendrocytes in the CNS, and its role in propagation of the action potential along the axon has been well studied. Myelin is an extension of the glial cell's plasma membrane, however it is biochemically very different. Part of this difference can be attributed to the composition of the proteins specifically targeted to the myelin membrane. One of these proteins, the myelin proteolipid protein (PLP) accounts for almost 50% of the total protein found in adult CNS myelin. Expression of the gene is tightly regulated. In humans, mutations in the P/p gene (which resides on the X chromosome) have been shown to be associated the X-linked dysmyelinating disorder Pelizaeus-Merzbacher disease (PMD), and some types of spastic paraplegia (SPG-2). Dysmyelination can arise from either elevated levels of P/p gene expression or lack of expression. Thus accurate expression of the P/p is critical, and elucidation of its regulation will be helpful in deciphering essential transcription regulatory elements that may be mutated in some people with PMD/SPG-2. On the other hand, elucidation of the mechanisms whereby the gene is regulated could provide insight into alternative causes of PMD/SPG-2, which do not arise from P/p gene mutations. Furthermore, it is important to understand how the gone is regulated, in order to help promote the remyelination process in people with demyelinating diseases. Multiple sclerosis, the most common demyelinating disease, generally occurs in adults substantially after the active myelination period in CNS development has ended. A deletion-transfection analysis has confirmed the importance of regulatory sequences located within the first intron that are essential for regulating P/p gone expression. One of these elements, the so-called ASE, for antisilencer/enhancer, appears to cause a dramatic increase in P/p gene expression during (and after) the myelination period of CNS development. We believe that multiple factors assemble on the ASE to form a stereospecific nucleoprotein structure termed an "enhanceosome." To understand how the ASE mediates P/p gone activation, the following specific aims have been proposed: 1) Characterize further the ASE, a positive cis-acting regulatory element located in intron 1 DNA, which promotes high levels of P/p gene expression in oligodendrocytes; 2) Identify the nuclear factors, which form a transcriptional regulatory complex on the ASE; 3) Elucidate the mechanism whereby the ASE nucleoprotein complex activates P/p gone expression in oligodendrocytes.