neurogenins,a Novel Family ofatonal-Related bHLH Transcription Factors, Are Putative Mammalian Neuronal Determination Genes That Reveal Progenitor Cell Heterogeneity in the Developing CNS and PNS

Neurogenin2 identifies a transplantable dopamine neuron precursor in the developing ventral mesencephalon

“…In the heterozygous Ngn2-GFP +/-mice, GFP is expressed in discrete regions of the developing cortex, diencephalon and lower brainstem-spinal cord, consistent with the previously described expression of Ngn2 (15,33), as well as the VM (Fig. 4A-C).…”

“…3B,C). As previously described (15,33), Ngn2 expression extends rostrally into the developing diencephalon where it is expressed outside the zone of dopaminergic neurogenesis. Mash1, another bHLH transcription factor of the proneural family, displays an expression pattern complementary to Ngn2 in the forebrain and has recently been shown to be necessary for the development of brainstem serotonergic neurons (26).…”

Thyroid hormone promotes neurogenesis in the Xenopus spinal cord

“…Simultaneously, the expression domains of XNeuroD and XMyT1 expand in a region lateral to the ventricular zone, similar to NeuroD expression in the mammalian spinal cord (Lee et al, 1995;Ma et al, 1996), suggesting that neurons are determined and begin to differentiate while they are displaced laterally from the ventricular zone. However, unlike mammalian Neurogenin1 and Neurogenin2 Sommer et al, 1996;Simmons et al, 2001;Scardigli et al, 2001;Gowan et al, 2001), X-NGNR-1 is not expressed in broad domains of the ventricular zone during this third phase, suggesting that spinal neurogenesis in larvae is largely regulated by other neuronal determination genes (see e.g., Lee, 1997;Guillemot, 1999;Brunet and Ghysen, 1999).…”

Induction of neurogenin‐1 expression by sonic hedgehog: Its role in development of trigeminal sensory neurons

“…They are formed by the cephalic neural crest located in posterior mesencephalic and most-anterior rhombencephalic axial levels (trigeminal neural crest cells) and by the trigeminal placode, which is of ectodermal origin (Le Douarin and Kalcheim, 1999). It has been shown that sensory neurons, including trigeminal sensory neurons are specified by neurogenin-1 and -2 (ngn-1 and ngn-2), transcription factors that belong to Drosophila atonal-related basic helixloop-helix (bHLH) type factors (Sommer et al, 1996;Anderson, 1999). Trigeminal ganglia are completely lost in ngn-1 null mutants.…”