Xie Yufen, Zhou Sichang, Jiang Zhongliang, Dai Jing, Puscheck Elizabeth E, Lee Icksoo, Parker Graham, Hüttemann Maik, Rappolee Daniel A
CS Mott Center for Human Growth and Development, Department of Ob/Gyn, Reproductive Endocrinology and Infertility, Wayne State University School of Medicine, Detroit, MI 48201, USA.
CS Mott Center for Human Growth and Development, Department of Ob/Gyn, Reproductive Endocrinology and Infertility, Wayne State University School of Medicine, Detroit, MI 48201, USA; Program for Reproductive Sciences, Department of Physiology, Wayne State University School of Medicine, Detroit, MI 48201, USA.
Stem Cell Res. 2014 Nov;13(3 Pt A):478-91. doi: 10.1016/j.scr.2014.07.007. Epub 2014 Jul 30.
Dysfunctional stem cell differentiation into placental lineages is associated with gestational diseases. Of the differentiated lineages available to trophoblast stem cells (TSC), elevated O2 and mitochondrial function are necessary to placental lineages at the maternal-placental surface and important in the etiology of preeclampsia. TSC lineage imbalance leads to embryonic failure during uterine implantation. Stress at implantation exacerbates stem cell depletion by decreasing proliferation and increasing differentiation. In an implantation site O2 is normally ~2%. In culture, exposure to 2% O2 and fibroblast growth factor 4 (FGF4) enabled the highest mouse TSC multipotency and proliferation. In contrast, hypoxic stress (0.5% O2) initiated the most TSC differentiation after 24h despite exposure to FGF4. However, hypoxic stress supported differentiation poorly after 4-7 days, despite FGF4 removal. At all tested O2 levels, FGF4 maintained Warburg metabolism; mitochondrial inactivity and aerobic glycolysis. However, hypoxic stress suppressed mitochondrial membrane potential and maintained low mitochondrial cytochrome c oxidase (oxidative phosphorylation/OxPhos), and high pyruvate kinase M2 (glycolysis) despite FGF4 removal. Inhibiting OxPhos inhibited optimum differentiation at 20% O2. Moreover, adding differentiation-inducing hyperosmolar stress failed to induce differentiation during hypoxia. Thus, differentiation depended on OxPhos at 20% O2; hypoxic and hyperosmolar stresses did not induce differentiation at 0.5% O2. Hypoxia-limited differentiation and mitochondrial inhibition and activation suggest that differentiation into two lineages of the labyrinthine placenta requires O2>0.5-2% and mitochondrial function. Stress-activated protein kinase increases an early lineage and suppresses later lineages in proportion to the deviation from optimal O2 for multipotency, thus it is the first enzyme reported to prioritize differentiation.
功能失调的干细胞向胎盘谱系的分化与妊娠疾病有关。在滋养层干细胞（TSC）可分化的谱系中，升高的氧气水平和线粒体功能对于母胎表面的胎盘谱系是必需的，并且在子痫前期的病因中起重要作用。TSC谱系失衡会导致子宫着床期间的胚胎失败。着床时的应激通过减少增殖和增加分化来加剧干细胞耗竭。在着床部位，氧气通常约为2%。在培养中，暴露于2%的氧气和成纤维细胞生长因子4（FGF4）可使小鼠TSC的多能性和增殖能力达到最高。相比之下，低氧应激（0.5%氧气）在24小时后引发了最多的TSC分化，尽管同时暴露于FGF4。然而，尽管去除了FGF4，但低氧应激在4 - 7天后对分化的支持较差。在所有测试的氧气水平下，FGF4维持了瓦伯格代谢；线粒体无活性和有氧糖酵解。然而，尽管去除了FGF4，低氧应激仍抑制了线粒体膜电位，并维持了低水平的线粒体细胞色素c氧化酶（氧化磷酸化/OxPhos）和高水平的丙酮酸激酶M2（糖酵解）。抑制氧化磷酸化会抑制20%氧气水平下的最佳分化。此外，在低氧期间添加诱导分化的高渗应激未能诱导分化。因此，在20%氧气水平下，分化依赖于氧化磷酸化；低氧和高渗应激在0.5%氧气水平下不会诱导分化。低氧限制分化以及线粒体抑制和激活表明，向迷路胎盘的两个谱系的分化需要氧气>0.5 - 2%以及线粒体功能。应激激活蛋白激酶会增加早期谱系，并根据与多能性最佳氧气水平的偏差比例抑制后期谱系，因此它是首个被报道能优先进行分化的酶。
