Han Songyan, Tan Christopher, Ding Junjun, Wang Jianlong, Ma'ayan Avi, Gouon-Evans Valerie
Department of Cell, Developmental and Regenerative Biology, Black Family Stem Cell Institute, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA.
Department of Pharmacological Science, Mount Sinai Center for Bioinformatics, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA.
Stem Cell Res. 2018 Jul;30:163-170. doi: 10.1016/j.scr.2018.06.004. Epub 2018 Jun 21.
Liver organogenesis requires complex cell-cell interactions between hepatic endoderm cells and adjacent cell niches. Endothelial cells are key players for endoderm hepatic fate decision. We previously demonstrated that the endothelial cell niche promotes hepatic specification of mouse embryonic stem cell(ESC)-derived endoderm through dual repression of Wnt and Notch pathways in endoderm cells. In the present study, we dissected further the mechanisms by which endothelial cells trigger endoderm hepatic specification. Using our previously established in vitro mouse ESC system mimicking the early hepatic specification process, endoderm cells were purified and co-cultured with endothelial cells to induce hepatic specification. The comparison of transcriptome profiles between hepatic endoderm cells isolated from co-cultures and endoderm cells cultured alone revealed that VEGF signaling instructs hepatic specification of endoderm cells through endothelial VEGFR2 activation. Additionally, epigenetic mark inhibition assays upon co-cultures uncovered that histone acetylation and DNA methylation promote hepatic specification while histone methylation inhibits it. This study provides an efficient 2D platform modelling the endothelial cell niche crosstalk with endoderm, and reveals mechanisms by which endothelial cells promote hepatic specification of mouse ESC-derived endoderm cells through endothelial VEGFR2 activation and endoderm epigenetic modifications.
肝脏器官发生需要肝内胚层细胞与相邻细胞龛之间复杂的细胞间相互作用。内皮细胞是内胚层肝脏命运决定的关键参与者。我们之前证明，内皮细胞龛通过对内胚层细胞中Wnt和Notch信号通路的双重抑制来促进小鼠胚胎干细胞（ESC）来源的内胚层向肝脏的特化。在本研究中，我们进一步剖析了内皮细胞触发内胚层肝脏特化的机制。利用我们之前建立的模拟早期肝脏特化过程的体外小鼠ESC系统，纯化内胚层细胞并与内皮细胞共培养以诱导肝脏特化。对从共培养物中分离的肝内胚层细胞与单独培养的内胚层细胞的转录组图谱进行比较，发现VEGF信号通过内皮VEGFR2激活指导内胚层细胞的肝脏特化。此外，共培养后的表观遗传标记抑制试验发现，组蛋白乙酰化和DNA甲基化促进肝脏特化，而组蛋白甲基化则抑制肝脏特化。本研究提供了一个模拟内皮细胞龛与内胚层相互作用的高效二维平台，并揭示了内皮细胞通过内皮VEGFR2激活和内胚层表观遗传修饰促进小鼠ESC来源的内胚层细胞肝脏特化的机制。
