Chuang Jen-Hua, Tung Li-Chu, Yin Yi, Lin Yenshou
Department of Life Science, National Taiwan Normal University, Taipei 116,Taiwan.
Stem Cell Res. 2013 Nov;11(3):1117-28. doi: 10.1016/j.scr.2013.08.003. Epub 2013 Aug 12.
Although the mammalian target of rapamycin complex 1 (mTORC1) functions as an important signaling complex in many cellular processes, the role of mTORC1 in neurons derived from embryonic stem cells (ESCs) has been less explored. Here, using a modified protocol to differentiate mouse ESCs (mESCs) into almost uniform glutamatergic neurons, we explored the importance of raptor/mTORC1 in the differentiation of mESCs. Raptor gene-trap mESCs, and raptor-knockdown mESCs formed smaller-sized embryonic bodies than the wild type and failed to undergo neuronal differentiation. Treatment with 1μM rapamycin starting at the point when neuronal precursors began to differentiate from mESCs caused the gradual loss of neurites, shrinkage of soma, and a decreased ratio of neurite length to cell number over 48 to 72h of treatment. This change was accompanied by activation of caspase-3 and S6 kinase (S6K), but not 4E-binding protein 1 (4EBP1). Knockdown of raptor during neuronal differentiation from mESCs also resulted in gradual loss of neurites and shrinkage of cell bodies. Loss of neurite density resulting from rapamycin treatment could be reversed by overexpression of S6K T389E. Taken together, these data demonstrate that raptor/mTORC1/S6K plays a critical role in the differentiation and survival of neurons derived from mESCs.
尽管雷帕霉素靶蛋白复合物1（mTORC1）在许多细胞过程中作为一种重要的信号复合物发挥作用，但mTORC1在源自胚胎干细胞（ESC）的神经元中的作用尚未得到充分研究。在这里，我们使用一种改良方案将小鼠胚胎干细胞（mESC）分化为几乎均一的谷氨酸能神经元，探讨了猛禽/ mTORC1在mESC分化中的重要性。猛禽基因陷阱mESC和猛禽敲低mESC形成的胚胎体比野生型小，并且未能进行神经元分化。从神经元前体开始从mESC分化时起用1μM雷帕霉素处理，在48至72小时的处理过程中导致神经突逐渐丧失、胞体收缩以及神经突长度与细胞数量的比率降低。这种变化伴随着半胱天冬酶-3和S6激酶（S6K）的激活，但不包括4E结合蛋白1（4EBP1）。在从mESC进行神经元分化过程中敲低猛禽也导致神经突逐渐丧失和细胞体收缩。雷帕霉素处理导致的神经突密度丧失可通过S6K T389E的过表达来逆转。综上所述，这些数据表明猛禽/ mTORC1 / S6K在源自mESC的神经元的分化和存活中起关键作用。
