缺氧诱导内皮祖细胞中孤儿核受体基因Nur77的表达

The Orphan Nuclear Receptor Gene Nur77 Expression Induced by Hypoxia in Endothelial Progenitor Cells

孤儿核受体Nur77蛋白是早期反应转录因子之一,多种刺激因子如缺氧可诱导其迅速表达,参与调控细胞增殖、存活、分化等过程。内皮祖细胞移植可治疗缺血性疾病,缺氧是其移植后主要的早期刺激因素,缺氧诱导下内皮祖细胞的基因表达及其增殖、分化、凋亡的变化目前尚不清楚。本文研究了大鼠骨髓来源的内皮祖细胞缺氧诱导下Nur77基因的表达变化。通过RT-PCR和Western印迹方法检测Nur77mRNA、蛋白质的表达,发现正常氧浓度下内皮祖细胞中Nur77基因几乎不表达,而1%氧浓度诱导30min时Nur77基因即迅速表达,其mRNA表达量于缺氧1h达到峰值,随后下降,缺氧4h时表达量仍高于正常氧浓度下的表达量(P<0.05);其蛋白质的表达量持续增加并于4h达到峰值。本研究证实了大鼠骨髓来源的内皮祖细胞中存在Nur77基因,缺氧可诱导Nur77基因迅速表达,这种表达可能对内皮祖细胞生物学特性的改变产生影响。

Orphan nuclear receptor Nur77 was one of early response transcription factors expressed under many stimuli such as hypoxia, and has been shown to be functionally involved in cell apoptosis, proliferation and differentiation, endothelial progenitor cell （EPC） had been used to treat ischemic disease. Hypoxia was the main and early stimulation after EPC transplantation in ischemic tissue; however, the gene expression and bionomic changes of EPC under hypoxia condition had not been well understood. Therefore we studied the dynamic changes of Nur77 gene expression in EPC isolated from rat＇s bone marrow Nur77 mRNA and protein levels detected using reverse （BM-EPC） and cultured in a hypoxia environment, with transcriptase PCR and Western blotting. We found that Nur77 gene was not expressed in BM-EPC cultured in normal oxygen concentration while its expression was significantly augmented after cultured in 1% oxygen concentration for 30 min, and that mRNA achieved its highest level within 1 h, then decreased. Nevertheless, the mRNA level of Nur77 remained significantly higher in hypoxia environment 4 h, compared with that in normal oxygen concentration （P〈0.05）. However, Nur77 increased continuously and achieved its highest level within 4 h. We thereby demonstrated in this study that Nur77 gene existed in BM-EPC, and the expression of Nur77 gene was induced by hypoxia.