A response element for the homeodomain transcription factor Ptx3 in the tyrosine hydroxylase gene promoter
A response element for the homeodomain transcription factor Ptx3 in the tyrosine hydroxylase gene promoter
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DOI：
10.1046/j.1471-4159.2000.0741829.x
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发表时间：
2000-05-01
影响因子：
4.7
通讯作者：
Burbach, JPH
中科院分区：
文献类型：
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作者：
Cazorla, P;Smidt, MP;Burbach, JPH
酪氨酸羟化酶（Tyrosine hydroxylase，TH）是儿茶酚胺类物质生物合成的限速酶，存在于不同类型的神经系统和非神经组织。TH基因的转录调控，这是复杂的和高度可变的不同组织之间，反映了这种异质性。我们最近分离出一个同源结构域转录因子，命名为Ptx 3，这是唯一的表达在多巴胺能神经元的黑质pars腹侧被盖区，一起形成中脑多巴胺能系统。这种严格的本地化和它的一致诱导表达与TH基因在发展过程中提出了一个可能的作用，这个转录因子在TH基因的控制。我们在这里报告的Ptx 3的反应元件位于位置-50到-45大鼠TH启动子的存在。瞬时转染TH启动子构建体和电泳迁移率变动分析使用Ptx 3含有核提取物表明，该地区结合Ptx 3蛋白，并赋予TH基因的转录效果。根据细胞类型，Ptx 3的作用是在Neuro 2A神经母细胞瘤细胞中TH启动子活性增强8 - 12倍，或在非神经元人胚肾293细胞中抑制60-80%。尽管Ptx 3结合位点和TH基因中的主要环AMP反应元件密切相关，但Ptx 3和环AMP调节剂之间没有相互作用。在与孤儿核受体Nurr 1，这是所需的中脑多巴胺能神经元的TH基因的诱导相结合，TH启动子的Ptx 3的活性增强在Neuro 2A细胞。在该细胞类型中，Nurr 1单独对TH启动子仅显示出非常弱的活性。结果表明，同源结构域蛋白Ptx 3有可能作用于TH基因的启动子在一个显着的细胞类型依赖性的方式。提示Ptx 3参与中脑多巴胺能神经元TH表达的调节。
Tyrosine hydroxylase (TH) is the rate-limiting enzyme in the biosynthesis of catecholamines, which takes place in different types of neuronal systems and nonneuronal tissues. The transcriptional regulation of the TH gene, which is complex and highly variable among different tissues, reflects this heterogeneity. We recently isolated a homeodomain transcription factor, named Ptx3, that is uniquely expressed in the dopaminergic neurons of the substantia nigra pars compacta and ventral tegmental area, which together form the mesencephalic dopaminergic system. This strict localization and its coinciding induction of expression with the TH gene during development suggested a possible role for this transcription factor in the control of the TH gene. We report here the presence of a responsive element for Ptx3 located at position -50 to -45 of the rat TH promoter. Transient transfections using TH promoter constructs and electrophoretic mobility shift assays using Ptx3-containing nuclear extracts demonstrated that this region binds Ptx3 protein and confers a transcriptional effect on the TH gene. Depending on the cell type, the effect of Ptx3 was an eight- to 12-fold enhancement of TH promoter activity in Neuro2A neuroblastoma cells, or a 60-80% repression in nonneuronal human embryonic kidney 293 cells. Despite the close association of the Ptx3-binding site and the major cyclic AMP-response element in the TH gene, no interplay was found between Ptx3 and cyclic AMP-modulating agents. In combination with the orphan nuclear receptor Nurr1, which is required for the induction of the TH gene in mesencephalic dopaminergic neurons, the TH promoter activity to Ptx3 was enhanced in Neuro2A cells. Nurr1 alone displayed only very weak activity on the TH promoter in this cell type. The results demonstrate that the homeodomain protein Ptx3 has the potential to act on the promoter of the TH gene in a markedly cell type-dependent fashion. This suggests that Ptx3 contributes to the regulation of TH expression In mesencephalic dopaminergic neurons.