加齢医学研究所雑誌第55巻第1号 平成16年3月

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 総  説
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Tbx 遺伝子 進化と発生のdriving force

東北大学加齢医学研究所 神経機能情報研究分野

小 椋 利 彦

要  旨
 Tbx遺伝子はT-boxをDNA結合ドメインとしてもつ転写因子をコードしている.Tbx遺伝子は,ショウジョウバエからヒトに至る広範な生物種に見つかり,きわめて大きな遺伝子群を作っている.ヒトなどの高等脊椎動物では20程度の遺伝子が確認されており,それぞれの遺伝子は多様な組織,器官に発現しており,組織の発生や分化に重要な働きを持っている.一つの祖先遺伝子から進化し,これほど多くのTbx遺伝子が分岐してきたことは,そのまま脊椎動物が進化の過程で形態の多様化,複雑化を起こしてきたことに関連している.本説では,Tbx遺伝子がもつ多彩な機能を論じ,また先天性形態異常との関連についても言及して,この遺伝子群がもつ特異な性質を概説したい.

加齢研誌55(1), 1-6, 2004.

 

Tbx genes as a driving force for the evolution and the development

Toshihiko OGURA

Department of Developmental Neurobiology, Division of Brain Sciences,
Institute of Development, Aging and Cancer, Tohoku University

  T-box (Tbx) genes play key roles during organogenesis and pattern formation in both vertebrate and invertebrate embryos. They encode a group of transcription factors characterized by a highly conserved DNA-binding motif (T-box) and its unusual mode of DNA recognition. By a combination of embryological and genetic approaches, a picture is emerging that Tbx genes belong to highly conserved genetic networks.
  Tbx2, Tbx3, Tbx4 and Tbx5 genes are derived from a common ancestral gene, which gave rise to a small gene complex by two duplication events during evolution of tetrapod animals. Due to heterochronic evolution, these four Tbx genes show unique and definitive expression in various tissues, such as limb buds, retina and hearts. Recent studies have shown that the diversification of these Tbx genes have been involved in the evolution of body plans.
  This review presents data on the functional roles played by these Tbx genes during vertebrate development, highlighting the Tbx genes as a key player for the evolution and the diversification of vertebrate body plans.

Key words: Tbx genes, limb, heart, evolution, development

Kareiigaku Kenkyusho Zasshi 55(1), 1-6, 2004.