Geng Zhe, Li Ping, Tan Li, Song Houyan
Key Laboratory of Molecular Medicine, Ministry of Education, Fudan University, Shanghai 200032, China ; Institute of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Lanzhou University, Gansu 730000, China.
Key Laboratory of Molecular Medicine, Ministry of Education, Fudan University, Shanghai 200032, China.
Stem Cells Int. 2015;2015:657325. doi: 10.1155/2015/657325. Epub 2015 Mar 31.
RNA-binding protein TIAR has been suggested to mediate the translational silencing of ARE-containing mRNAs. To analyze the functions of TIAR, we established RNAi and genetic rescue assays. We evaluated the expression of neuroectoderm markers Pax6 and nestin, mesoderm markers brachyury and Flk1, and hypoblast and definitive endoderm markers Sox17 and Gata6 during EB differentiation and found that knockdown TIAR expression restrained the differentiation of E14 cells. We assessed gene expression levels of Flk-1 and VE-cadherin and observed attenuated differentiation of E14 cells into endothelial cells upon downregulation of TIAR gene expression. As such, we hypothesized an essential role of TIAR related to EB differentiation. As TIAR inhibits the translation of c-myc, we proposed that downregulation of TIAR results in restrained differentiation of E14 cells, due in part to the function of c-myc. We found that TIAR inhibited c-myc expression at the translational level in E14 cells; accordingly, a reduction of TIAR expression promoted self-renewal of pluripotent cells and attenuated differentiation. Additionally, we established that TIAR inhibited TIA-1 expression at the translational level in E14 cells. Taken together, we have contributed to the understanding of the regulatory relationships between TIAR and both c-myc and TIA-1.
RNA结合蛋白TIAR被认为可介导含富AU元件（ARE）的mRNA的翻译沉默。为了分析TIAR的功能，我们建立了RNA干扰和基因拯救试验。我们评估了胚胎干细胞（EB）分化过程中神经外胚层标志物Pax6和巢蛋白、中胚层标志物短尾相关蛋白和Flk1，以及下胚层和定形内胚层标志物Sox17和Gata6的表达，发现敲低TIAR表达会抑制E14细胞的分化。我们评估了Flk-1和血管内皮钙黏蛋白的基因表达水平，观察到TIAR基因表达下调后E14细胞向内皮细胞的分化减弱。因此，我们推测TIAR在EB分化中起重要作用。由于TIAR抑制c-myc的翻译，我们提出TIAR的下调导致E14细胞分化受到抑制，部分原因是c-myc的功能。我们发现TIAR在E14细胞的翻译水平上抑制c-myc表达；因此，TIAR表达的降低促进了多能细胞的自我更新并减弱了分化。此外，我们证实TIAR在E14细胞的翻译水平上抑制TIA-1表达。综上所述，我们有助于理解TIAR与c-myc和TIA-1之间的调控关系。
