ABSTRACT
Objective:To investigate the role of nicotinamide (NIC) in the differentiation of neural crest cells from human embryonic stem cells (hESCs), and lay the foundation for the induction of hESC-derived corneal endothelial cells.Methods:hESCs line H1 cultured for 5-7 days was used for induction.According to the different components of the neural crest induction medium, cells were assigned into different groups for 7-days induction, including group treated without NIC cultured in induction medium only, group treated with NIC cultured in induction medium containing 10 mmol/L NIC, NIC+ resveratrol (Res) group cultured in induction medium containing 10 mmol/L NIC and 10 μmol/L Res and Sirtinol group cultured in induction medium containing 10 μmol/L Sirtinol.Res and Sirtinol were used as SIRT1 activity agonist and inhibitor, respectively.The relative mRNA expression levels of hESCs and neural crest cell markers were detected by real-time fluorescence quantitative PCR at 1, 3, 5 and 7 days during the induction.The expression of neural crest cells markers after 7 days of induction was assayed by immunofluorescence staining.The induction efficiency of NIC and the effect of SIRT1 regulation on human natural killer 1 (HNK-1) positive cells expression were evaluated through flow cytometry analysis of percentages of nerve growth factor receptor (P75) and HNK-1 + cells. Results:Compared with the group treated without NIC, the mRNA expressions of totipotent genes octamer transcription factor 4 (OCT4) and homeodomain proteins (NANOG) were significantly decreased, and the mRNA expression levels of neural crest cell markers P75, HNK-1, SRY-related HMG box (SOX) 9 and SOX10 were significantly increased in the group treated with NIC after 5 days of induction (all at P<0.05). In the group treated without NIC, P75 was weakly expressed, and HNK-1 was sporadically expressed, and transcription factor AP-2β (AP-2β) and paired-like homeodomain transcription factor 2 (PITX2) were not detected.In the group treated with NIC, P75, HNK-1, AP-2β and PITX2 were strongly expressed.The proportion of P75 + HNK-1 + cells and P75 + cells were both significantly higher in the group treated with NIC than without NIC ( t=8.481, P=0.001; t=2.987, P=0.041). The percentage of HNK-1 + cells in groups treated without and with NIC, NIC+ Res group and Sirtinol group were (34.267±12.522)%, (89.633±1.358)%, (64.667±6.429)% and (86.300±3.460)%, respectively, with a statistically significant overall difference ( F=36.799, P<0.001). The proportion of HNK-1 + cells in NIC+ Res group was significantly lower than that in the groups treated with NIC and Sirtinol (all at P<0.05). Conclusions:NIC promotes the differentiation of hESCs-derived neural crest cells by inhibiting the activity of SIRT1 to enhance the expression of HNK-1.NIC treatment may provide a new strategy for source of seed cells in the treatment of neural crest cell-related diseases, such as corneal endothelial transplantation.
ABSTRACT
Objective To investigate the inhibiting effect of CGP77675 (CGP),a Src inhibitor,on epithelial-mesenchymal transition (EMT) of human retinal pigment epithelial (RPE) cells induced by transformation growth factor-β1 (TGF-β1).Methods Human RPE cell line (ARPE19 cells) was cultured in vitro and divided into control group,TGF-β1 group and TGF-β1 +CGP group.Corresponding agent was added into culture medium based on grouping.The morphology of the cells were examined under the optical microscope 3 days after culture.The expressions of EMT-related genes and proteins in the cells were detected by real-time quantitative PCR and Western blot,respectively,including fibronectin 1 (FN 1),and plasminogen activation inhibitor 1 (PAI1),and the expressions of zonula occludens protein 1 (ZO1) and cytoskeleton protein filamentous actin (F-actin) were detected by immunofluorescence staining.MTT assay was employed to evaluate the cell proliferation rate.The migration distance of the cells was measured by scratch test.Results The ARPE19 cells in the control group showed an epithelial-like morphology and F-actin and ZO-1 were expressed along cell membrane.In the TGF-β1 group,the cells appeared to be fibrous-like,and the fluorescence staining of F-actin was disordered and ZO-1 was discontinuous on the cell membrane.The cells in the TGF-β1 +CGP group remained to be an epithelial-like in shape with clear and complete expressions of F-actin and ZO-1.The relative expressions of FN1 mRNA and PAI1 mRNA in the cells were 0.211 ± 0.080 and 0.116±0.073,1.000±0.001 and 1.000±0.001,0.368±0.097 and 0.362±0.048 in the control group,TGF-β1 group and TGF-β1 +CGP groups,showing significant differences among the groups (F=33.14,82.92;both at P＜0.01),with the highest expressions ofFN1 mRNA and PAI1 mRNA in the TGF-β1 group (all at P＜0.05).The relative expressions of FN1 and PAI1 proteins were 0.166±0.055 and 0.327±0.066,1.000±0.001 and 1.000± 0.001,0.143 ± 0.030 and 0.260 ± 0.077 in the control group,TGF-β1 group and TGF-β1 + CGP group,with significant differences among three groups (F=181.90,48.85;both at P＜0.01),and the expressions FN1 and PAI1 proteins were significantly higher in the TGF-β1 than those in the control group and TGF-β1 +CGP group (all at P＜0.05).The cell proliferative rate in the TGF-β1+CGP group was (79.30±3.44) ％ and (54.80±7.39) ％ at the third day and seventh day after culture,which were significantly reduced in comparison with (99.50 ± 1.00)％ and (99.10±0.50)％ in the control group as well as (95.10±4.20)％ and (92.10±4.50)％ in the TGF-β1 group (all at P＜0.05).The migration distance was disappeared in the TGF-β1 group,and the scratch width was not obviously changed in the TGF-β1 +CGP group.Conclusions Src inhibitor can inhibit EMT process of ARPE19 cells induced by TGF-β1,indicating that Src signaling pathway may play a critical role in EMT of RPE cells.