Tong Ran, Wang Han, Jin Ying, Li Hui
Department of Histoembryology, Genetics and Developmental Biology, Shanghai Key Laboratory of Reproductive Medicine, Shanghai Jiao Tong University School of Medicine, Shanghai, China.
Department of Histoembryology, Genetics and Developmental Biology, Shanghai Key Laboratory of Reproductive Medicine, Shanghai Jiao Tong University School of Medicine, Shanghai, China; CAS Key Laboratory of Tissue Microenvironment and Tumor, Shanghai Institute of Nutrition and Health, CAS Center for Excellence in Molecular Cell Science, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai, China; Basic Clinical Research Center, Ren Ji Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China.
Biochem Biophys Res Commun. 2022 Sep 3;619:27-33. doi: 10.1016/j.bbrc.2022.06.023. Epub 2022 Jun 9.
Transcription factors are key determinants of lineage commitment during mammalian development. However, the function and molecular mechanism for the transcription factors in the formation of three primary germ layers during human embryonic development are not fully elucidated. Here, we report that homeobox-containing transcription factor HESX1 plays a critical role in mesendodermal (ME) commitment of human embryonic stem cells (hESCs). Our results show that expression of HESX1 in hESCs is regulated by OCT4 and NANOG, and that its expression level changes with hESC differentiation. We find that knockdown of HESX1 does not disrupt the undifferentiated state of hESCs, in terms of cell morphology and expression levels of pluripotency-associated genes. However, HESX1 deficiency in hESCs impairs their ME commitment, whereas forced expression of HESX1 significantly enhances ME marker expression during ME commitment. Interestingly, HESX1 knockdown in hESCs represses ERK1/2 signaling activated by ME induction, while overexpression of HESX1 markedly enhances ERK1/2 activity during ME commitment of hESCs. Of note, MEK inhibitor PD0325901 weakens or even eliminates HESX1 overexpression-mediated promotive effects on ME induction in a dosage-dependent manner. Together, this study identifies a novel role of HESX1 in hESC commitment to ME cells and establishes the functional link between a transcription factor and lineage-associated signaling. These findings would help to better understand early human development and develop more efficient protocols to induce hESC differentiation to desired lineages.
转录因子是哺乳动物发育过程中细胞谱系定向分化的关键决定因素。然而，转录因子在人类胚胎发育过程中三胚层形成中的功能和分子机制尚未完全阐明。在此，我们报道含同源框转录因子HESX1在人类胚胎干细胞（hESC）向中内胚层（ME）分化过程中起关键作用。我们的结果表明，hESC中HESX1的表达受OCT4和NANOG调控，且其表达水平随hESC分化而变化。我们发现，敲低HESX1在细胞形态和多能性相关基因表达水平方面并不破坏hESC的未分化状态。然而，hESC中HESX1的缺失损害其向ME分化的能力，而强制表达HESX1则在ME分化过程中显著增强ME标志物的表达。有趣的是，hESC中敲低HESX1可抑制ME诱导激活的ERK1/2信号，而HESX1过表达则在hESC向ME分化过程中显著增强ERK1/2活性。值得注意的是，MEK抑制剂PD0325901以剂量依赖的方式减弱甚至消除HESX1过表达介导的对ME诱导的促进作用。总之，本研究确定了HESX1在hESC向ME细胞分化中的新作用，并建立了转录因子与谱系相关信号之间的功能联系。这些发现将有助于更好地理解人类早期发育，并开发更有效的方案来诱导hESC分化为所需谱系。
