Notch Exhibits Ligand Bias and Maneuvers Stage-Specific Steering of Neural Differentiation in Embryonic Stem Cells

Abstract

Notch dictates multiple developmental events, including stem cell maintenance and differentiation, through intercellular communication. However, its temporal influence during early development and, of particular interest, its regulation of binary fate decision at different stages during neurogenesis are among the least explored. Here, using an embryonic stem cell (ESC) model, we have deciphered Notch ligand preference during ESC commitment to different germ layers and determined the stage-specific temporal effect of Notch during neural differentiation. ESCs during maintenance remain impervious to Notch inhibition. However, Notch activation promotes differentiation even in the presence of leukemia inhibitory factor (LIF), displaying ligand preference-associated lineage discrimination, where Jagged-1 favors neural commitment and Delta-like-4 favors the mesoderm. This differential ligand action involves a combination of Notch receptors influencing specific downstream target gene expression. Though Notch activation during early neural differentiation specifically promotes neural stem cells or early neural progenitors and delays their maturation, its inhibition promotes late neural progenitors and expedites neurogenesis, with a preference for neurons over glia. However, gliogenesis is promoted upon Notch activation only when executed in combination with ciliary neurotrophic factor. Thus, our investigation underscores a multifaceted role of Notch, demonstrating the interdependency of ligand usage and lineage specification and Notch acting as a master switch, displaying stage-specific influence on neurogenesis.