Jung Ji-Hye, Kang Ka-Won, Kim Jihea, Hong Soon-Chul, Park Yong, Kim Byung Soo
1 Institute of Stem Cell Research, Korea University , Seoul, Korea.
2 Department of Biomedical Science, Graduate School of Medicine, Korea University , Seoul, Korea.
Stem Cells Dev. 2016 Jul 1;25(13):1006-19. doi: 10.1089/scd.2015.0395.
On the basis of our previous report verifying that chemokine (C-X-C motif) receptor 2 (CXCR2) ligands in human placenta-derived cell conditioned medium (hPCCM) support human pluripotent stem cell (hPSC) propagation without exogenous basic fibroblast growth factor (bFGF), this study was designed to identify the effect of CXCR2 manipulation on the fate of hPSCs and the underlying mechanism, which had not been previously determined. We observed that CXCR2 inhibition in hPSCs induces predominant differentiation to mesoderm and endoderm with concomitant loss of hPSC characteristics and accompanying decreased expression of mammalian target of rapamycin (mTOR), β-catenin, and human telomerase reverse transcriptase (hTERT). These phenomena are recapitulated in hPSCs propagated in conventional culture conditions, including bFGF as well as those in hPCCM without exogenous bFGF, suggesting that the action of CXCR2 on hPSCs might not be associated with a bFGF-related mechanism. In addition, the specific CXCR2 ligand growth-related oncogene α (GROα) markedly increased the expression of ectodermal markers in differentiation-committed embryoid bodies derived from hPSCs. This finding suggests that CXCR2 inhibition in hPSCs prohibits the propagation of hPSCs and leads to predominant differentiation to mesoderm and endoderm owing to the blockage of ectodermal differentiation. Taken together, our results indicate that CXCR2 preferentially supports the maintenance of hPSC characteristics as well as facilitates ectodermal differentiation after the commitment to differentiation, and the mechanism might be associated with mTOR, β-catenin, and hTERT activities.
基于我们之前的报告，该报告证实人胎盘来源细胞条件培养基（hPCCM）中的趋化因子（C-X-C基序）受体2（CXCR2）配体可在无外源性碱性成纤维细胞生长因子（bFGF）的情况下支持人多能干细胞（hPSC）的增殖，本研究旨在确定CXCR2调控对hPSC命运的影响及其潜在机制，而这在之前尚未确定。我们观察到，hPSC中CXCR2的抑制会诱导其主要分化为中胚层和内胚层，同时丧失hPSC特征，并伴随雷帕霉素哺乳动物靶标（mTOR）、β-连环蛋白和人端粒酶逆转录酶（hTERT）表达的降低。这些现象在传统培养条件下（包括添加bFGF）以及无外源性bFGF的hPCCM中培养的hPSC中均有重现，这表明CXCR2对hPSC的作用可能与bFGF相关机制无关。此外，特异性CXCR2配体生长相关癌基因α（GROα）显著增加了源自hPSC的分化定型胚状体中外胚层标志物的表达。这一发现表明，hPSC中CXCR2的抑制会阻止hPSC的增殖，并由于外胚层分化受阻而导致主要分化为中胚层和内胚层。综上所述，我们的结果表明，CXCR2优先支持hPSC特征的维持，并在分化定型后促进外胚层分化，其机制可能与mTOR、β-连环蛋白和hTERT的活性有关。
