Role of the Glucagon-like Peptide-1 Receptor Agonist in Maintaining Pluripotency in Human Embryonic Stem Cells

Previous studies have demonstrated that glucagon-like peptide-1 (GLP-1) stimulates β-cell formation and insulin secretion. Currently, there has been no report in understanding the effect of GLP-1 / its agonist exendin-4 in differentiation of human embryonic stem cells (hESCs) to definitive endodermal (DE). We hypothesized that exendin-4 signaling in hESCs via GLP-1 receptor (GLP-1R) may have potential role in DE differentiation. The effect of Ex-4 on pluripotent hESCs and the combined effect of Ex-4 and activin A-treated hESC-derived DE were examined. Analysis by quantitative real-time PCR (qPCR) demonstrates that Ex-4 alone was not sufficient to enhance DE formation in hESCs. On the other hand, a combinatorial treatment with activin A and Ex-4 resulted in significant decrease in expression levels of DE markers. The miRNA expression profiles between activin A-treated hESCs and activin A/Ex-4-treated hESCs after 5 days of treatment demonstrated similar expression levels of endoderm and pancreas-associated miRNAs. However, it was shown that the levels of pluripotency-associated miRNAs, miR-302a* and miR302c*, were upregulated in the presence of Ex-4. Furthermore, it was observed that exposure to bFGF and Ex-4 in apoptosis-inducing medium resulted in downregulation of CASP3 and p53. Taken together, these data revealed the possibility of Ex-4 in maintaining pluripotency and inhibiting apoptosis. The knowledge of GLP-1 signaling pathways could be useful for understanding the mechanism of GLP-1R-ligand interactions and their relevance to hESC development.