Résumé
We have characterized different neuronal subpopulations derived from in vitro differentiation of embryonic stem (ES) cells using as markers the expression of several homeodomain transcription factors. Following treatment of embryo-like aggregates with retinoic acid (RA), Pax-6, a protein expressed by ventral central nervous system (CNS) progenitors is induced. In contrast,
Pax-7 expressed in vivo by dorsal CNS progenitors, and
erbB3, a gene expressed by neural crest cells and its derivatives, are almost undetectable. CNS neuronal subpopulations generated expressed combinations of markers characteristic of somatic motoneurons (
Islet-1/2,
Lim-3, and
HB-9), cranial motoneurons (
Islet-1/2 and
Phox2b) and interneurons (
Lim-1/2 or
EN1). Molecular characterization of neuron subtypes generated from ES cells should considerably facilitate the identification of new genes expressed by restricted neuronal cell lineages.