Activin a efficiently specifies definitive endoderm from human embryonic stem cells only when phosphatidylinositol 3-kinase signaling is suppressed
Activin a efficiently specifies definitive endoderm from human embryonic stem cells only when phosphatidylinositol 3-kinase signaling is suppressed
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DOI：
10.1634/stemcells.2006-0219
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发表时间：
2007-01-01
期刊：
影响因子：
5.2
通讯作者：
Dalton, Stephen
中科院分区：
文献类型：
--
作者：
McLean, Amanda B.;D'Amour, Kevin A.;Dalton, Stephen
人类胚胎干细胞(HESCs)对决定其多能性、增殖、存活和分化状态的信号做出反应。在这篇报道中，我们证明了磷脂酰肌醇3-激酶(PI3K)拮抗hESCs对转化生长因子β家族成员如激活素A和Nodal的分化能力。抑制PI3K信号可以有效地促进人胚胎干细胞分化为中胚层，然后通过激活蛋白/结节信号使其分化为最终的内胚层(DE)。在无饲养层的小鼠胚胎成纤维细胞条件培养液中培养的人胚胎干细胞，在用PI3K途径的抑制剂如LY 294002和AKT1-II处理5天后，大约70%-80%的细胞转化为DE。基于微阵列和定量聚合酶链式反应的基因表达谱分析表明，在这些条件下最终的内胚层形成与激活素A升高和低胎牛血清(FCS)/基因敲除血清替代(KSR)的规范密切相关。胰岛素/胰岛素样生长因子(IGF)信号的减少被发现是细胞命运承诺进入DE的关键。胰岛素/胰岛素样生长因子水平存在于FCS/KSR中，通常用于促进hESCs的自我更新，但拮抗分化。综上所述，我们证明了hESC-DE的产生需要两个条件：激活素/Nodal家族成员的信号传递和PI3K通过胰岛素/IGF产生的抑制信号的释放。这些发现对我们理解hESC的自我更新和早期细胞命运决策具有重要的意义。
Human ESCs (hESCs) respond to signals that determine their pluripotency, proliferation, survival, and differentiation status. In this report, we demonstrate that phosphatidylinositol 3-kinase (PI3K) antagonizes the ability of hESCs to differentiate in response to transforming growth factor beta family members such as Activin A and Nodal. Inhibition of PI3K signaling efficiently promotes differentiation of hESCs into mesendoderm and then definitive endoderm (DE) by allowing them to be specified by Activin/Nodal signals present in hESC cultures. Under conditions where hESCs are grown in mouse embryo fibroblast-conditioned medium under feeder-free conditions, similar to 70%-80% are converted into DE following 5 days of treatment with inhibitors of the PI3K pathway, such as LY 294002 and AKT1-II. Microarray and quantitative polymerase chain reaction-based gene expression profiling demonstrates that definitive endoderm formation under these conditions closely parallels that following specification with elevated Activin A and low fetal calf serum (FCS)/knockout serum replacement (KSR). Reduced insulin/insulin-like growth factor (IGF) signaling was found to be critical for cell fate commitment into DE. Levels of insulin/IGF present in FCS/KSR, normally used to promote self-renewal of hESCs, antagonized differentiation. In summary, we show that generation of hESC-DE requires two conditions: signaling by Activin/Nodal family members and release from inhibitory signals generated by PI3K through insulin/IGF. These findings have important implications for our understanding of hESC self-renewal and early cell fate decisions.