ネズミの成長ホルモン遺伝子のc-erb-A結合部位は,甲状腺ホルモンによるトランス活性化を媒介する
C K Glass1, R Franco, C Weinberger
1Centre for Molecular Genetics, University of California, San Diego, La Jolla 92093.
Nature
|October 22, 1987
まとめ
甲状腺ホルモン (T3) は,DNAに結合する核受容体を通して,成長ホルモンの遺伝子転写を刺激する. 研究者らは,ラット成長ホルモン遺伝子の特定のT3受容体結合部位を特定し,c-erb-A遺伝子産物であることを確認した.
科学分野:
- 分子内分泌学 分子内分泌学
- 遺伝子規制 遺伝子規制
- 核受容体の機能について
背景:
- 甲状腺ホルモン (3,5,3-トリオドチロニン,T3) は,下垂体細胞における成長ホルモン (GH) 遺伝子発現を含む遺伝子転写を調節する.
- T3の作用は,DNAの調節要素に結合する核T3受容体によって媒介されるが,その浄化と特定の結合部位は,豊富度が低いため,特定することが困難である.
- 最近の研究では,c-erb-A遺伝子の産物を,受容体特性を有する高親和性甲状腺ホルモン結合体として特定しました.
研究 の 目的:
- 特定のT3受容体-DNA相互作用を検出する方法を開発する.
- ネズミの成長ホルモン (GH) 遺伝子プロモーターのT3受容体によって認識されるDNA配列を特定する.
- T3調節されたGH遺伝子転写を媒介するc-erb-A遺伝子産物の役割を調査する.
主な方法:
- 核T3受容体結合を検出するためのアビジン-バイオチン複合体のDNA結合測定法の開発.
- オリゴヌクレオチドトランスフェクションアッセイは,ネズミの垂体GC2細胞でT3調節を評価する.
- ヒトの胎盤c-erb-A遺伝子の in vitro翻訳製品を使用したインビトロ結合測定法.
主要な成果:
- アビジン-バイオチンアッセイでは,ラットの甲状腺T3受容体と,ラットのGH遺伝子開始部位から164bp上流に位置する5'CAGGGACGTGACCGCA3'のシーケンスの特定の高親和結合が検出されました.
- この配列を含むオリゴヌクレオチドは,感染した細胞内の異質なプロモーター (ヘルペスシンプレックスウイルスチミジンキナーゼ) にT3調節を与えました.
- 特定されたDNA配列は,ヒトの胎盤c-erb-A遺伝子製品にインビトロで特異的に結合した.
結論:
- 人間のc-erb-A遺伝子製品は,GH遺伝子に対するT3の転写効果の媒介者である可能性が高い.
- 特定されたDNA配列は,ネズミのGH遺伝子のT3応答要素を表しています.
- pituitary細胞の追加の核因子は,GH遺伝子T3応答要素に結合するT3受容体を調節する可能性があります.
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