A case for revisiting Nodal signaling in human pluripotent stem cells

Abstract

Nodal is a transforming growth factor-β (TGF-β) superfamily member that plays a number of critical roles in mammalian embryonic development. Nodal is essential for the support of the peri-implantation epiblast in the mouse embryo, and subsequently acts to specify mesendodermal fate at the time of gastrulation, and later, left-right asymmetry. Maintenance of human pluripotent stem cells (hPSCs) in vitro is dependent on Nodal signaling. Because it has proven difficult to prepare a biologically active form of recombinant Nodal protein, Activin or TGFB1 are widely used as surrogates for NODAL in hPSC culture. Nonetheless, the expression of the components of an endogenous Nodal signaling pathway ..