Clinical and Translational Research Center of Shanghai First Maternity and Infant Health Hospital, Shanghai Key Laboratory of Signaling and Disease Research, School of Life Science and Technology, Tongji University, Shanghai 200092, People's Republic of China.
Proc Natl Acad Sci U S A. 2013 Feb 19;110(8):2858-63. doi: 10.1073/pnas.1212769110. Epub 2013 Feb 5.
Fibroblasts can be reprogrammed to induced pluripotent stem cells (iPSCs) by application of transcription factors octamer-binding protein 4 (Oct4), SRY-box containing gene 2 (Sox2), Kruppel-like factor 4 (Klf4), and c-Myelocytomatosis oncogene (c-Myc) (OSKM), but the underlying mechanisms remain unclear. Here, we report that exogenous Oct4 and Sox2 can bind at the promoter regions of mir-141/200c and mir-200a/b/429 cluster, respectively, and induce the transcription activation of miR-200 family during the OSKM-induced reprogramming. Functional suppression of miR-200s with specific inhibitors significantly represses the OSKM-caused mesenchymal-to-epithelial transition (MET, an early event in reprogramming of fibroblasts to iPSCs) and iPSC generation, whereas overexpression of miR-200s promotes the MET and iPSC generation. Mechanistic studies showed that miR-200s significantly repress the expression of zinc finger E-box binding homeobox 2 (ZEB2) through directly targeting its 3' UTR and direct inhibition of ZEB2 can mimic the effects of miR-200s on iPSC generation and MET process. Moreover, the effects of miR-200s during iPSC generation can be blocked by ZEB2 overexpression. Collectively, our findings not only reveal that members of the miR-200 family are unique mediators of the reprogramming factors Oct4/Sox2, but also demonstrate that the miR-200/ZEB2 pathway as one critical mechanism of Oct4/Sox2 to induce somatic cell reprogramming at the early stage.
成纤维细胞可通过应用转录因子八聚体结合蛋白 4(Oct4)、含 Sry 框基因 2(Sox2)、Krüppel 样因子 4(Klf4)和 c-Myelocytomatosis 癌基因(c-Myc)(OSKM)重编程为诱导多能干细胞(iPSCs),但其潜在机制尚不清楚。在这里,我们报告外源 Oct4 和 Sox2 可以分别结合在 mir-141/200c 和 mir-200a/b/429 簇的启动子区域,并在 OSKM 诱导的重编程过程中诱导 miR-200 家族的转录激活。用特异性抑制剂抑制 miR-200s 的功能可显著抑制 OSKM 引起的间充质向上皮转化(MET,成纤维细胞重编程为 iPSCs 的早期事件)和 iPSC 的产生,而过表达 miR-200s 则促进 MET 和 iPSC 的产生。机制研究表明,miR-200s 通过直接靶向其 3'UTR 显著抑制锌指 E 框结合同源盒 2(ZEB2)的表达,并直接抑制 ZEB2 可模拟 miR-200s 对 iPSC 产生和 MET 过程的影响。此外,miR-200s 在 iPSC 产生过程中的作用可以被 ZEB2 的过表达所阻断。总之,我们的研究结果不仅揭示了 miR-200 家族成员是重编程因子 Oct4/Sox2 的独特介质,而且还证明了 miR-200/ZEB2 途径是 Oct4/Sox2 诱导体细胞重编程的早期阶段的一个关键机制。