Discovering the role of VEGF signaling pathway in mesendodermal induction of human embryonic stem cells.

Human embryonic stem cells (hESCs) have the unique feature of unlimited self-renewal and differentiation into derivatives of all three germ layers in human body, providing a powerful in vitro model for studying cell differentiation. FGF2, BMP4 and TGF-β signaling have been shown to play crucial roles in mesendodermal differentiation of hESCs. However, their underlying molecular mechanisms and other signaling pathways potentially involved in mesendodermal differentiation of hESCs remain to be further investigated. In this study, we uncover that VEGF signaling pathway plays a critical role in the mesendodermal induction of hESCs. Treating hESCs with Lenvatinib, a pan-inhibitor of VEGF receptors (VEGFRs), impedes their mesendodermal induction. Conversely, overexpression of VEGFA165, a major human VEGF isoform, promotes the mesendodermal differentiation. Similar to the VEGFR inhibitor, MEK inhibitor PD0325901 hinders mesendodermal induction of hESCs. In contrast, overexpression of ERK2, an intrinsically active ERK2 mutant, markedly reduces the inhibitory effect of the VEGFR inhibitor. Thus, the MEK-ERK cascade plays an important role for the function of VEGF signaling pathway in the mesendodermal induction of hESCs. All together, this study identifies the critical role of VEGF signaling pathway as well as potential crosstalk of VEGF signaling pathway with other known signaling pathways in mesendodermal differentiation of hESCs.