Sousa Kyle M, Mira Helena, Hall Anita C, Jansson-Sjöstrand Lottie, Kusakabe Moriaki, Arenas Ernest
Laboratory of Molecular Neurobiology, Department of Medical Biochemistry and Biophysics, Karolinska Institute, Stockholm, Sweden.
Stem Cells. 2007 Feb;25(2):511-9. doi: 10.1634/stemcells.2006-0238. Epub 2006 Oct 12.
Nurr1 is an orphan nuclear receptor required for the development of midbrain dopaminergic neurons. To better understand the molecular consequences of Nurr1 expression, we compared the transcriptomes of two independent control and Nurr1-expressing NSC lines using Affymetrix cDNA microarrays. These data reveal the regulation of genes involved in promoting cell survival (trophic/growth factors and stress response genes) and in preventing cell death (decreased caspase-3 and caspase-11 expression). We found that conditioned medium from Nurr1-expressing NSC lines enhanced the survival of midbrain dopaminergic neurons in primary cultures and that Nurr1-expressing NSC lines themselves were more resistant to oxidative stress. These findings are accompanied by a dynamic pattern of gene regulation that is consistent with a role for Nurr1 in promoting both the acquisition of brain-region-specific identity (Engrailed-1) and neuronal differentiation (tubulin beta III). Interestingly, our gene expression profiles suggested that tenascin-C was regulated by Nurr1 in developing dopaminergic neurons. This was further confirmed in vitro and in Nurr1 knockout mice where low levels of tenascin-C mRNA were observed. Analysis of tenascin-C-null mice revealed an increase in the number of Nurr1(+) cells that become tyrosine hydroxylase-positive (TH(+)) dopaminergic neurons at embryonic day 11.5, suggesting that tenascin-C normally delays the acquisition of TH by Nurr1(+) precursors. Thus, our results confirm the presence of both secreted and cell-intrinsic survival signals modulated by Nurr1 and suggest that Nurr1 is a key regulator of both survival and dopaminergic differentiation.
Nurr1是中脑多巴胺能神经元发育所必需的孤儿核受体。为了更好地理解Nurr1表达的分子后果，我们使用Affymetrix cDNA微阵列比较了两个独立的对照和表达Nurr1的神经干细胞系的转录组。这些数据揭示了参与促进细胞存活（营养/生长因子和应激反应基因）和预防细胞死亡（caspase-3和caspase-11表达降低）的基因调控。我们发现，来自表达Nurr1的神经干细胞系的条件培养基可提高原代培养物中脑多巴胺能神经元的存活率，并且表达Nurr1的神经干细胞系本身对氧化应激更具抗性。这些发现伴随着动态的基因调控模式，这与Nurr1在促进脑区特异性身份（Engrailed-1）的获得和神经元分化（微管蛋白βIII）中的作用一致。有趣的是，我们的基因表达谱表明，在发育中的多巴胺能神经元中，腱生蛋白-C受Nurr1调控。这在体外和Nurr1基因敲除小鼠中得到了进一步证实，在这些小鼠中观察到腱生蛋白-C mRNA水平较低。对腱生蛋白-C基因敲除小鼠的分析显示，在胚胎第11.5天，成为酪氨酸羟化酶阳性（TH(+)）多巴胺能神经元的Nurr1(+)细胞数量增加，这表明腱生蛋白-C通常会延迟Nurr1(+)前体细胞获得TH。因此，我们的结果证实了由Nurr1调节的分泌型和细胞内在存活信号的存在，并表明Nurr1是存活和多巴胺能分化的关键调节因子。
