Department of Microbiology, Immunology, and Molecular Genetics, University of California, Los Angeles, California 90095, USA.
Stem Cells. 2011 Dec;29(12):1952-62. doi: 10.1002/stem.748.
Understanding the intrinsic and extrinsic signals that regulate the molecular basis of the pluripotent state may improve our understanding of mammalian embryogenesis, different states of pluripotency, and our ability to tailor lineage differentiation. Although the role of the PI3K/Akt pathway in the self-renewal and maintenance of mESCs is well-established, the specific contribution of the pathway or of its negative regulator, PTEN, in the maintenance of the human pluripotent state is less understood. To explore the PI3K/AKT pathway in human embryonic stem cell (hESC) pluripotency and differentiation, we generated stable PTEN knockdown (KD) hESCs using short hairpin RNA. Similar to mESCs, we found that PTEN KD hESCs have increased self-renewal, cell survival, and proliferation over multiple passages compared to control cells. However, in contrast to mESCs, in vitro, PTEN KD hESCs differentiated inefficiently in directed differentiation assays, in part due to the continued maintenance of OCT4 and NANOG expression. In teratoma assays, PTEN KD hESCs generated tissues from the three germ layers, although with a bias toward neuroectoderm differentiation. These results demonstrate that PTEN is a key regulator of hESC growth and differentiation, and manipulation of this pathway may improve our ability to regulate and understand the pluripotent state.
理解调节多能性状态分子基础的内在和外在信号，可能有助于我们深入了解哺乳动物胚胎发生、不同的多能性状态，以及我们对谱系分化进行定制的能力。虽然 PI3K/Akt 通路在 mESC 的自我更新和维持中的作用已得到充分证实，但该通路或其负调节剂 PTEN 在维持人类多能性状态中的具体作用还不太清楚。为了研究 PI3K/AKT 通路在人胚胎干细胞（hESC）多能性和分化中的作用，我们使用短发夹 RNA 生成了稳定的 PTEN 敲低（KD）hESC。与 mESC 相似，我们发现与对照细胞相比，PTEN KD hESC 在多次传代中具有更高的自我更新、细胞存活和增殖能力。然而，与 mESC 不同的是，在体外定向分化实验中，PTEN KD hESC 的分化效率较低，部分原因是 OCT4 和 NANOG 的表达持续维持。在畸胎瘤实验中，PTEN KD hESC 产生了来自三个胚层的组织，尽管偏向神经外胚层分化。这些结果表明，PTEN 是 hESC 生长和分化的关键调节剂，对该通路的操纵可能提高我们调控和理解多能性状态的能力。
