PIASγ represses the transcriptional activation induced by the nuclear receptor Nurr1
PIASγ represses the transcriptional activation induced by the nuclear receptor Nurr1
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DOI：
10.1074/jbc.m308113200
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发表时间：
2004-01-16
影响因子：
4.8
通讯作者：
Andrés, ME
中科院分区：
文献类型：
--
作者：
Galleguillos, D;Vecchiola, A;Andrés, ME
Nurr 1是腹侧多巴胺能神经元发育所必需的转录因子。在寻找Nurr 1功能的调节机制时，我们确定了SUMO（小泛素样修饰剂）-E3泛素蛋白异肽连接酶，PIASgamma，作为Nurr 1的相互作用伴侣。过表达的PIASgamma和Nurr 1共定位于转染细胞的细胞核中，并且它们的相互作用通过共免疫沉淀和谷胱甘肽S-转移酶下拉测定来证明。PIASgamma与Nurr 1的共表达导致人工NGFI-B反应元件（NBRE）报告基因以及由天然酪氨酸羟化酶启动子驱动的报告基因的Nurr 1依赖性转录激活的有效抑制。我们确定了两个共识SUMO化位点Nurr 1。在一个SUMO位点中赖氨酸91被精氨酸取代增强了Nurr 1的转录活性，而在第二个SUMO位点中赖氨酸577被精氨酸取代降低了Nurr 1的转录活性。有趣的是，PIASgamma诱导的Nurr 1活性抑制不需要两个sumoylation位点，因为每个突变体被有效抑制野生型Nurr 1。此外，突变不改变Nurr 1核定位。最后，我们提供的证据表明，Nurr 1和PIASgamma共存于啮齿动物中枢神经系统的几个核，通过展示Nurr 1蛋白和PIASgamma mRNA在相同的细胞中的共表达。总之，我们的研究确定PIASgamma作为Nurr 1的转录辅助调节因子，并表明这种相互作用可能在调节Nurr 1靶基因的表达中具有生理作用。
Nurr1 is a transcription factor essential for the development of ventral dopaminergic neurons. In search for regulatory mechanisms of Nurr1 function, we identified the SUMO ( small ubiquitin-like modifier)-E3 ubiquitin-protein isopeptide ligase, PIASgamma, as an interaction partner of Nurr1. Overexpressed PIASgamma and Nurr1 co-localize in the nuclei of transfected cells, and their interaction is demonstrated through co-immunoprecipitation and glutathione S-transferase pulldown assays. Co-expression of PIASgamma with Nurr1 results in a potent repression of Nurr1-dependent transcriptional activation of an artificial NGFI-B response element (NBRE) reporter as well as of a reporter driven by the native tyrosine hydroxylase promoter. We identified two consensus sumoylation sites in Nurr1. The substitution of lysine 91 by arginine in one SUMO site enhanced the transcriptional activity of Nurr1, whereas the substitution of lysine 577 by arginine in the second SUMO site decreased transcriptional activity of Nurr1. Interestingly, PIASgamma-induced repression of Nurr1 activity does not require the two sumoylation sites, because each mutant is repressed as efficiently as the wild type Nurr1. In addition, the mutations do not alter Nurr1 nuclear localization. Finally, we provide evidence that Nurr1 and PIASgamma co-exist in several nuclei of the rodent central nervous system by demonstrating the co-expression of Nurr1 protein and PIASgamma mRNA in the same cells. In conclusion, our studies identified PIASgamma as a transcriptional co-regulator of Nurr1 and suggest that this interaction may have a physiological role in regulating the expression of Nurr1 target genes.