Regulation of neurotrophin-3 gene transcription by Sp3 and Sp4 in neurons
Regulation of neurotrophin-3 gene transcription by Sp3 and Sp4 in neurons
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DOI：
10.1111/j.1471-4159.2006.04216.x
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发表时间：
2007-01-01
影响因子：
4.7
通讯作者：
Tsuda, Masaaki
中科院分区：
文献类型：
--
作者：
Ishimaru, Naoki;Tabuchi, Akiko;Tsuda, Masaaki
神经营养因子-3 （NT-3）是神经营养因子中的一员，在神经元的发育、功能和可塑性中起着至关重要的作用。先前的研究表明，NT-3基因转录是由分别位于1A （EIA）和1B （EIB）上游的启动子A和B驱动的。然而，驱动NT-3基因转录的转录因子和DNA元件仍有待确定。在这里，我们分析了NT-3基因的启动子区域，发现含有EIB的NT-3转录物主要在优先利用启动子B的皮质神经元中表达，并且转录需要两个串联重复的gc -box，位于启动子B内的-100和-60碱基对之间。电泳迁移率转移和染色质免疫沉淀分析表明，特异性蛋白（Sp）3和Sp4都能与GC盒内的Sp1结合序列结合。皮层神经元中显性阴性Sp3和Sp4小干扰RNA的表达降低了NT-3基因启动子的活性。Sp1家族成员，特别是Sp4的过度表达导致NT-3基因启动子的增加。这些发现表明NT-3基因是Sp4在大脑中大量表达的靶基因。
Neurotrophin-3 (NT-3), a neurotrophin member, plays crucial roles in neuronal development, function and plasticity. Previous studies have demonstrated that NT-3 gene transcription is driven by alternative promoters A and B, located upstream of exons 1A (EIA) and 1B (EIB), respectively. However, the transcription factors and DNA elements that drive NT-3 gene transcription remain to be identified. Here, we analysed the promoter region of the NT-3 gene and found that an NT-3 transcript containing EIB is predominantly expressed in cortical neurons which preferentially utilize promoter B, and two tandemly repeated GC-boxes, located between -100 and -60 base pairs within promoter B, are required for the transcription. Electrophoretic mobility shift and chromatin immunoprecipitation assays revealed that both specificity protein (Sp)3 and Sp4 were able to bind to the Sp1 binding sequences within the GC boxes. Expression of dominant-negative Sp3 and Sp4 small interfering RNA in cortical neurons reduced the activity of the NT-3 gene promoter. Over-expression of Sp1 family members, especially Sp4, resulted in an increase of the NT-3 gene promoter. These findings indicate that the NT-3 gene is a target gene for Sp4 that is abundantly expressed in the brain.