Characterization of an intronic enhancer that regulates myelin proteolipid protein (Plp) gene expression in oligodendrocytes
Characterization of an intronic enhancer that regulates myelin proteolipid protein (Plp) gene expression in oligodendrocytes
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DOI：
10.1002/jnr.20640
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发表时间：
2005-11-01
影响因子：
4.2
通讯作者：
Wight, PA
中科院分区：
文献类型：
--
作者：
Meng, FX;Zolova, O;Wight, PA
髓鞘蛋白脂质蛋白（Plp）基因在少突胶质细胞中表达，编码中枢神经系统（CNS）成熟髓鞘中最丰富的蛋白质（约占50%）。Plp基因活性在发育早期低至不存在，但在CNS发育的活跃髓鞘形成期急剧增加。我们实验室的工作表明，小鼠Plp基因表达的时间调节是由位于Plp内含子1 DNA内的正调控元件介导的。我们把这个调节元件/区域称为ASE（抗沉默子/增强子）。ASE位于外显子1 DNA下游约1 kb处，包含近100 bp。为了了解ASE增强少突胶质细胞中Pip基因表达的机制，制备了Plp-lacZ构建体并转染到小鼠少突胶质细胞系（N20.1）中。本文提供的结果表明，Plp启动子/5 '侧翼DNA中的上游调控元件a.当胸苷激酶（TK）启动子取代Plp启动子时，ASE工作得非常好。然而，ASE的相对位置似乎很重要。当置于2.4kb的Plp 5 '侧翼DNA的上游或lacZ表达盒的下游时，ASE不再有效。因此，ASE可能必须在内含子的环境中才能发挥作用。为了开始鉴定ASE中的关键核苷酸，将来自大鼠、人、牛和猪Plp基因的正向序列与小鼠序列交换。结果表明，大鼠的正向同源序列可以替代小鼠的ASE，而不像人、牛或猪的ASE。(c)2005 Wiley-Liss，Inc.
The myelin proteolipid protein (Plp) gene is expressed in oligodendrocytes and encodes the most abundant protein (similar to 50%) present in mature myelin from the central nervous system (CNS). Plp gene activity is low to nonexistent early in development but sharply increases, concurrently with the active myelination period of CNS development. Work from our laboratory suggests that the temporal regulation of Plp gene expression in mice is mediated by a positive regulatory element located within Plp intron 1 DNA. We have termed this regulatory element/region ASE (for antisilencer/enhancer). The ASE is situated approximately 1 kb downstream of exon 1 DNA and encompasses nearly 100 bp. To understand the mechanisms-by which the ASE augments Pip gene expression in oligodendrocytes, Plp-lacZ constructs were generated and transfected into a mouse oligodendroglial cell line (N20.1). Results presented here demonstrate that upstream regulatory elements in the Plp promoter/5'-flanking DNA a. re not required for ASE activity; the ASE worked perfectly well when the thymidine kinase (TK) promoter was substituted for the Plp promoter. However, the relative location of the ASE appears to be important. When placed upstream of 2.4 kb of Plp 5'-flanking DNA, or downstream of the lacZ expression cassette, the ASE was no longer effective. Thus, the ASE might have to be in the context of the intron in order to function. To begin to identify the crucial nucleotides within the ASE, orthologous sequences from rat, human, cow, and pig Plp genes were swapped for the mouse sequence. Results presented here demonstrate that the orthologous sequence from rat can substitute for the mouse ASE, unlike those from human, cow, or pig. (c) 2005 Wiley-Liss, Inc.