BMP and FGF‐2 regulate neurogenin‐2 expression and the differentiation of sensory neurons and glia

We have examined the effects of signaling molecules and Notch signaling on the mechanisms regulating neurogenin (ngn) ‐2 expression. This ngn‐2 is a transcription factor that is essential for the specification of early differentiating sensory neurons in the dorsal root ganglia. In the presence of bone morphogenetic protein (BMP), anti–ngn‐2‐positive cells appeared in mouse trunk neural crest cell cultures, and they expressed Brn3, indicating that ngn‐2–expressing cells are sensory neurons. These cells did not differentiate after fibroblast growth factor (FGF) ‐2 treatment or after Notch activation. The suppression of ngn‐2 expression by FGF‐2 was recovered by treatment with a Notch signaling inhibitor. Thus, FGF‐2 may prevent ngn‐2 expression through Notch activation. Whereas BMP‐4 inhibited glial differentiation, FGF‐2 promoted gliogenesis by means of Notch activation. Our data suggest that BMP and FGF‐2 act as positive and negative regulators in ngn‐2 expression, respectively, and that these signaling molecules regulate the differentiation of sensory neurons and glia. Developmental Dynamics 235:646–655, 2006. © 2006 Wiley‐Liss, Inc.