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東京大学代謝生理化学セミナー Giovanni Levi博士


日時: 平成 17 年 11 月 4 日(金) 16:00~17:00

場所: 東大医学部本館3階 大講堂

講師: Giovanni Levi 博士
(Laboratoire de Physiologie Générale et Comparée&s_comma; Muséum National dʼHistoire Naturelle&s_comma; Paris&s_comma; France)

演題: Role and regulation of Dlx genes during craniofacial development:
evolutionary implications

Dlx genes are homeobox-containing genes involved in the control of limbs and head development. We have inactivated by homologous recombination in the mouse Dlx5&s_comma; Dlx6 and Dlx5 and 6 simultaneously. The first part of this presentation will be devoted to the comparative analysis of the craniofacial phenotypes of these mutant mice; for the first time the phenotype of Dlx6 mutant mice will be reported. The notion of a dosage effect of homeobox genes in the control of morphogenesis will be discussed. In the second part of the talk we will analyse the regulation of Dlx genes during craniofacial development. In particular the effects of Retinoic Acid (RA) on the activation of Dlx genes will be presented. Indeed&s_comma; administration of RA to pregnant females induces severe craniofacial malformations of the embryo.
The origin of these teratogenic effects was&s_comma; so far&s_comma; poorly explained as cranial neural crest cells (CNCC)&s_comma; which colonise the first branchial arch and give rise to the face&s_comma; do not express RA or its receptors. We will show how RA acts on the expression of Dlx genes through two totally separate regulatory pathways.
These deregulations of Dlx gene expression are at the basis of RA-induced craniofacial malformations. They lead to severe and complex alterations of the craniofacial architecture with appearance of structures characteristic of different vertebrate species. The evolutionary implications of these findings will be discussed.

問い合わせ先 東京大学大学院医学系研究科・代謝生理化学 栗原裕基
TEL: 03-5841-3496