Deconstructing cell determination: proneural genes and neuronal identity.
Vertebrates express scores of bHLH proteins during neural development. Earlier studies inspired by the established role of "proneural" genes in fly neurogenesis, as well as by the vertebrate bHLH myogenic program, focused on the reconstruction of bHLH gene cascades, which are thought to control successive steps leading to neuronal differentiation. Little attention has been paid thus far to the relationship between the diversity of neural bHLH genes and the diversity of neuronal phenotypes. This article reviews recent evidence that, akin to their fly counterparts, vertebrate neural bHLH genes probably confer not only "generic" neuronal properties, but also neuronal type-specific properties, inextricably linking neural determination and the specification of neuronal identity. We also speculate on the relations between positional information and gene activity, and on the evolutionary significance of the diversity of bHLH genes.
Brunet
J F
JF
Institut de Biologie du Développement de Marseille, CNRS-INSERM-Université de la Méditerranée, France.
Ghysen
A
A
D000818:Animals; D051792:Basic Helix-Loop-Helix Proteins; D002454:Cell Differentiation / Q000235:genetics; D004268:DNA-Binding Proteins / Q000235:genetics*; D004330:Drosophila / Q000166:cytology / Q000235:genetics; D018257:Helix-Loop-Helix Motifs; D008959:Models, Neurological; D009474:Neurons / Q000166:cytology*; D014157:Transcription Factors / Q000235:genetics*; D014714:Vertebrates
D051792:Basic Helix-Loop-Helix Proteins; D004268:DNA-Binding Proteins; D014157:Transcription Factors