The olig family: phylogenetic analysis and early gene expression in Xenopus tropicalis.
Dev Genes Evol. 2007-06-07; 217(7): 485-497
DOI: 10.1007/s00427-007-0158-z
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Bronchain OJ(1), Pollet N, Ymlahi-Ouazzani Q, Dhorne-Pollet S, Helbling JC,
Lecarpentier JE, Percheron K, Wegnez M.
Author information:
(1)Laboratoire Développement, Morphogenèse et Evolution, CNRS UMR 8080,
Université Paris-Sud, 91405, Orsay Cedex, France.
The olig genes form a small subfamily of basic helix-loop-helix transcription
factors. They were discovered in 2000 as genes required for oligodendrocyte
lineage specification. Since then, olig genes have been identified in various
vertebrate species and corresponding sequences accumulated within genomic
databases. Until now, three groups of olig genes have been characterized. Our
phylogenetic analysis demonstrates the existence of a fourth group, which we
named olig4. Genes of the four olig groups are present in actinopterygians and
amphibians, whereas mammals only possess olig1, 2, and 3. We also found one olig
gene in hemichordates, urochordates, and cephalochordates. Our expression study
during Xenopus tropicalis embryogenesis shows that the four olig genes have very
distinct expression patterns. Olig1 is very faintly expressed before the tadpole
stage, whereas olig2, 3, and 4 are expressed from the gastrula stage onward. The
olig3 expression during neurulation suggests a role in early anteroposterior
patterning of the brain. All these results indicate that olig genes are involved
in several developmental processes during early development.