Hirai Hiroyuki, Firpo Meri, Kikyo Nobuaki
Stem Cell Institute, University of Minnesota, Minneapolis, Minnesota 55455, USA; Department of Genetics, Cell Biology and Development, University of Minnesota, Minneapolis, Minnesota 55455, USA.
Stem Cell Institute, University of Minnesota, Minneapolis, Minnesota 55455, USA; Division of Endocrinology, Department of Medicine, University of Minnesota, Minneapolis, Minnesota 55455, USA.
Stem Cell Res. 2015 Nov;15(3):469-480. doi: 10.1016/j.scr.2015.09.002. Epub 2015 Sep 12.
Leukemia inhibitory factor (LIF) is widely used to establish and maintain naïve pluripotent stem cells, including mouse embryonic stem cells (ESCs) and induced pluripotent stem cells (iPSCs). Although the combination of chemical inhibitors called 2i can establish mouse iPSCs without LIF from primed pluripotent stem cells, it has been difficult, if not impossible, to establish mouse iPSCs from differentiated somatic cells without LIF. We previously showed that the fusion gene of the transactivation domain of MyoD and the full-length Oct4 (M3O) increases the efficiency of making iPSCs when transduced into fibroblasts along with Sox2, Klf4, and c-Myc (M3O-SKM). Here, we report that M3O-SKM allows for establishment of iPSCs without exogenous LIF from mouse embryonic fibroblasts. The established iPSCs remained undifferentiated and maintained pluripotency over 90 days without LIF as long as M3O was expressed. The iPSCs upregulated miR-205-5p, which was potentially involved in the LIF-independence by suppressing the two signaling pathways inhibited by 2i. The result indicates that potentiated Oct4 can substitute for the LIF signaling pathway, providing a novel model to link Oct4 and LIF, two of the most significant players in naïve pluripotency.
白血病抑制因子（LIF）被广泛用于建立和维持未分化的多能干细胞，包括小鼠胚胎干细胞（ESCs）和诱导多能干细胞（iPSCs）。尽管名为2i的化学抑制剂组合能够从已分化的多能干细胞中建立无需LIF的小鼠iPSCs，但从分化的体细胞中建立无LIF的小鼠iPSCs即便并非不可能，也一直颇具难度。我们之前表明，MyoD的反式激活结构域与全长Oct4的融合基因（M3O）在与Sox2、Klf4和c-Myc（M3O-SKM）一起转导至成纤维细胞时，可提高生成iPSCs的效率。在此，我们报告M3O-SKM能够从小鼠胚胎成纤维细胞中建立无需外源性LIF的iPSCs。所建立的iPSCs在无LIF的情况下保持未分化状态并维持多能性超过90天，只要M3O表达即可。这些iPSCs上调了miR-205-5p，其可能通过抑制2i所抑制的两条信号通路参与LIF非依赖性。该结果表明增强的Oct4可以替代LIF信号通路，提供了一个将Oct4和LIF联系起来的新模型，Oct4和LIF是未分化多能性中两个最重要的因素。
