TRANSCRIPTIONAL REGULATION OF THE MYELIN PROTEOLIPID PROTEIN GENE

本子项目是利用由NIH/NCRR资助的中心赠款提供的资源的众多研究子项目之一。子项目和研究者（PI）可能已经从另一个NIH来源获得了主要资金，因此可以在其他CRISP条目中表示。列出的机构是中心的，不一定是研究者的机构。哺乳动物髓磷脂蛋白脂蛋白（Plp）基因的表达与少突胶质细胞的分化密切相关，并在这些细胞活跃地向中枢神经系统神经元轴突形成髓鞘的时期达到峰值。Plp基因的低水平表达也在几种非少突胶质细胞类型中被检测到，包括睾丸的间质细胞，但这种表达的功能意义尚未确定。位于Plp基因第一个内含子内的几个调控元件/区域与Plp基因表达的时空调控有关。其中一个元件，被称为抗沉默/增强子（ASE），似乎通过抵消位于第一个内含子内的负调控元件的作用，介导了少突胶质细胞中Plp基因表达的急剧上升。非少突胶质细胞中Plp表达水平较低的一个可能解释是，ASE在这些细胞中的活性要低得多，并且在抵消负调控元件方面相对无效。为了验证这一假设，我们分析了一系列Plp内含子1缺失对瞬时转染小鼠间质细胞系（TM3）中连锁报告基因（lacZ）表达的影响。这些实验结果证实，Plp内含子1的ASE元件/区域在间质细胞中活性极低，而内含子内的一般和细胞类型特异性负调控元件在抑制报告基因表达方面非常活跃。初步证据还表明，位于内含子5端附近的一个与ASE不同的正调控元件可能在间质细胞中特异性起作用。这个问题将通过观察内含子5端附近额外缺失的影响进行更深入的探讨。（从2004年6月1日开始）

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Expression of the myelin proteolipid protein (Plp) gene in mammals is intimately tied to the differentiation of oligodendrocytes and reaches a peak during the period in which these cells are actively myelinating the axons of neurons in the central nervous system. Low-level expression of the Plp gene has also been detected in several non-oligodendroglial cell types, including the Leydig cells of the testis, but the functional significance of this expression has yet to be determined. Several regulatory elements/regions, located within the first intron of the Plp gene, have been implicated in the spatial and temporal regulation of Plp gene expression. One of these elements, designated the antisilencer/enhancer (ASE), appears to mediate a dramatic upsurge in Plp gene expression in oligodendrocytes by counteracting the effects of negative regulatory elements located within the first intron. One possible explanation for the lower level of Plp expression in non-oligodendroglial cells is that the ASE is much less active in these cells and is relatively ineffective in counteracting the negative regulatory elements. To test this hypothesis, we analyzed the effects of a series of Plp intron 1 deletions on the expression of a linked reporter gene (lacZ) in a transiently transfected mouse Leydig cell line (TM3). The results of these experiments confirmed that the ASE element/region of Plp intron 1 has minimal activity in Leydig cells, while general and cell type specific negative regulatory elements within the intron are very active in repressing expression of the reporter gene. Preliminary evidence also suggests that a positive regulatory element located near the 5 end of the intron, and distinct from the ASE, may function specifically in Leydig cells. This issue will be explored in more depth by looking at the effects of additional deletions near the 5 end of the intron. (to start June 1, 2004)