Xiao Lei, Yuan Xuan, Sharkis Saul J
Sidney Kimmel Comprehensive Cancer Center at Johns Hopkins, Baltimore, Maryland 21231, USA.
Stem Cells. 2006 Jun;24(6):1476-86. doi: 10.1634/stemcells.2005-0299. Epub 2006 Feb 2.
Human embryonic stem cells (hESCs) self-renew indefinitely while maintaining pluripotency. The molecular mechanism underlying hESCs self-renewal and pluripotency is poorly understood. To identify the signaling pathway molecules that maintain the proliferation of hESCs, we performed a microarray analysis comparing an aneuploid H1 hESC line (named H1T) versus euploid H1 hESC line because the H1T hESC line demonstrates a self-renewal advantage while maintaining pluripotency. We find differential gene expression for the Nodal/Activin, fibroblast growth factor (FGF), Wnt, and Hedgehog (Hh) signaling pathways in the H1T line, which implicates each of these molecules in maintaining the undifferentiated state, whereas the bone morphogenic protein (BMP) and Notch pathways could promote hESCs differentiation. Experimentally, we find that Activin A is necessary and sufficient for the maintenance of self-renewal and pluripotency of hESCs and supports long-term feeder and serum-free growth of hESCs. We show that Activin A induces the expression of Oct4, Nanog, Nodal, Wnt3, basic FGF, and FGF8 and suppresses the BMP signal. Our data indicates Activin A as a key regulator in maintenance of the stemness in hESCs. This finding will help elucidate the complex signaling network that maintains the hESC phenotype and function.
人类胚胎干细胞（hESCs）能无限自我更新，同时保持多能性。目前对hESCs自我更新和多能性的分子机制了解甚少。为了鉴定维持hESCs增殖的信号通路分子，我们进行了一项微阵列分析，比较了一个非整倍体H1 hESC系（命名为H1T）与整倍体H1 hESC系，因为H1T hESC系在保持多能性的同时表现出自我更新优势。我们发现H1T系中Nodal/激活素、成纤维细胞生长因子（FGF）、Wnt和刺猬信号通路（Hh）存在差异基因表达，这表明这些分子中的每一个都参与维持未分化状态，而骨形态发生蛋白（BMP）和Notch信号通路可促进hESCs分化。通过实验，我们发现激活素A对于维持hESCs的自我更新和多能性是必要且充分的，并支持hESCs在无饲养层和无血清条件下长期生长。我们表明激活素A可诱导Oct4、Nanog、Nodal、Wnt3、碱性FGF和FGF8的表达，并抑制BMP信号。我们的数据表明激活素A是维持hESCs干性的关键调节因子。这一发现将有助于阐明维持hESC表型和功能的复杂信号网络。
