Okamoto Shu-ichi, Sherman Katerina, Bai Guang, Lipton Stuart A
Center for Neuroscience and Aging, The Burnham Institute, La Jolla, CA 92037, USA.
Brain Res Mol Brain Res. 2002 Nov 15;107(2):89-96. doi: 10.1016/s0169-328x(02)00440-0.
The silencer factor NRSF/REST has been reported to restrict expression to neurons of a variety of genes, including that encoding NMDA receptor subunit type 1 (NR1), by suppressing transcription in nonneuronal cells. However, we recently reported that in addition to the absence of NRSF/REST-binding activity, another neuron-specific mechanism is necessary for high level expression of the NR1 gene in neurons. In this study, we explored the mechanism of induction of NR1 promoter activity during neuronal differentiation of the P19 cell line. We identified a 27 base pair GC-rich region in the promoter as an important element responsible for induction of the NR1 gene after neuronal differentiation. We found that the ubiquitous transcription factors SP1 and MAZ bind to this GC-rich region. Surprisingly, the binding activities of SP1 and MAZ are not remarkably changed after neuronal differentiation. Mutations in the SP1 and MAZ sites impair binding of SP1 and MAZ proteins and also decrease NR1 promoter activity. These findings suggest that SP1 and MAZ mediate enhancement of NR1 promoter activity during neuronal differentiation despite the fact that their binding activity does not change.
沉默因子NRSF/REST据报道可通过抑制非神经元细胞中的转录，将多种基因（包括编码N-甲基-D-天冬氨酸受体1型亚基（NR1）的基因）的表达限制在神经元中。然而，我们最近报道，除了缺乏NRSF/REST结合活性外，另一种神经元特异性机制对于神经元中NR1基因的高水平表达也是必需的。在本研究中，我们探讨了P19细胞系神经元分化过程中NR1启动子活性诱导的机制。我们在启动子中鉴定出一个27个碱基对的富含GC的区域，作为神经元分化后负责诱导NR1基因的重要元件。我们发现普遍存在的转录因子SP1和MAZ与这个富含GC的区域结合。令人惊讶的是，神经元分化后SP1和MAZ的结合活性没有明显变化。SP1和MAZ位点的突变会损害SP1和MAZ蛋白的结合，并降低NR1启动子活性。这些发现表明，尽管SP1和MAZ的结合活性没有改变，但它们在神经元分化过程中介导了NR1启动子活性的增强。
