Jt. Rifkin et al., Dynamic expression of neurotrophin receptors during sensory neuron genesisand differentiation, DEVELOP BIO, 227(2), 2000, pp. 465-480
To identify potential functions for neurotrophins during sensory neuron gen
esis and differentiation, we determined the temporal and spatial protein ex
pression patterns of neurotrophin receptors throughout the process of senso
ry neurogenesis in the dorsal root ganglia (DRG). We show that neurotrophin
receptors are expressed early, being first detected on subsets of migratin
g neural crest cells, and that trkC is among the earliest markers of neural
lineage specification. In the immature DRG, we find that both trkC and p75
(NTR) are expressed on subsets of dividing progenitor cells in vivo. Furthe
rmore, our data directly reveal distinct patterns of trk receptor expressio
n by individual sensory neurons from the time of their inception with all e
arly arising cells initially being trkC(+), some subsets of whom also coexp
ress either trkA or trkB or both. As sensory neurons innervate their target
s and establish their mature identities, the spectrum of trk receptors expr
essed by individual neurons is altered. The stereotyped trk receptor expres
sion profiles identified here may potentially correspond to distinct lineag
es of sensory neurons. These data, in conjunction with other studies, argue
for multiple functions for neurotrophins during the process of sensory neu
ron differentiation, including effects on both neural crest and DRG mitotic
ally active progenitor cells, in addition to possibly influencing the estab
lishment of sensory neuron identity. (C) 2000 Academic Press.