Epidermal-growth-factor-induced proliferation of astrocytes requires Egr transcription factors
Epidermal-growth-factor-induced proliferation of astrocytes requires Egr transcription factors
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DOI：
10.1242/jcs.048272
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发表时间：
2009-09-15
影响因子：
4
通讯作者：
Thiel, Gerald
中科院分区：
文献类型：
--
作者：
Mayer, Sabine I.;Roessler, Oliver G.;Thiel, Gerald
表皮生长因子(EGF)刺激星形胶质细胞增殖并触发转录因子Egr-1的生物合成，涉及细胞外信号调节蛋白激酶(ERK)信号通路的激活。野生型和Egr-1基因缺陷小鼠制备的星形胶质细胞的增殖率没有差异。然而，显性-负性Egr-1突变体的表达干扰了所有Egr蛋白的DNA结合，阻止了EGF诱导的星形胶质细胞增殖。对锌指DNA结合域中两个关键半胱氨酸残基的定点突变表明，Egr-1突变体的DNA结合是抑制EGF刺激的星形胶质细胞增殖所必需的。表达的NAB2(Egr-1、Egr-2和Egr-3的负调节因子)或Elk-1的显性-负突变(Egr-1生物合成的关键调节因子)可抑制EGF诱导的星形胶质细胞增殖。染色质免疫沉淀实验表明，Egr-1、Egr-2和Egr-3与EGF刺激的星形胶质细胞表达碱性成纤维细胞生长因子(BFGF)的基因结合。在EGF刺激的星形胶质细胞中，EGR-2和Egr-3也与碱性成纤维细胞生长因子基因相互作用，表明Egr-1的丢失被其他Egr蛋白补偿。综上所述，这些数据表明，Egr转录因子对于将EGF的有丝分裂信号转化为增殖反应是必不可少的。
Stimulation of astrocytes with epidermal growth factor (EGF) induced proliferation and triggered the biosynthesis of the transcription factor Egr-1, involving the activation of the extracellular signal-regulated protein kinase (ERK) signaling pathway. No differences in the proliferation rate of astrocytes prepared from wild-type or Egr-1-deficient mice were detected. However, expression of a dominant-negative mutant of Egr-1 that interfered with DNA-binding of all Egr proteins prevented EGF-induced proliferation of astrocytes. Site-directed mutagenesis of two crucial cysteine residues within the zinc finger DNA-binding domain revealed that DNA-binding of the Egr-1 mutant was essential to inhibit proliferation of EGF-stimulated astrocytes. Expression of NAB2 (a negative coregulator of Egr-1, Egr-2 and Egr-3) or a dominant-negative mutant of Elk-1 (a key regulator of Egr-1 biosynthesis) abolished EGF-induced proliferation of astrocytes. Chromatin immunoprecipitation experiments showed that Egr-1, Egr-2 and Egr-3 bound to the gene expressing basic fibroblast growth factor (bFGF) in EGF-stimulated astrocytes. Egr-2 and Egr-3 also interacted with the bFGF gene in EGF-stimulated astrocytes prepared from Egr-1-deficient mice, indicating that loss of Egr-1 is compensated by other Egr proteins. Together, these data show that Egr transcription factors are essential for conversion of the mitogenic signal of EGF into a proliferative response.