Smoothenedのヘッジホッグシグナル伝達活動は,タンパク質キナーゼAとカゼインキナーゼIによるリン酸化を必要とする
Jianhang Jia1, Chao Tong, Bing Wang
1Center for Developmental Biology, University of Texas Southwestern Medical Center, Dallas, Texas 75390, USA. jin.jiang@utsouthwestern.edu
Nature
|December 24, 2004
まとめ
タンパク質キナーゼA (PKA) とカゼインキナーゼI (CKI) は,スモートヘッド (Smo) をリン酸化することによってヘッジホッグ (Hh) 信号を調節する. このリン酸化は,動物の発達中にSmo細胞表面の蓄積と経路の活動を制御する.
科学分野:
- 発達生物学 発達生物学とは
- 細胞シグナル伝達 細胞信号伝達
- 分子生物学は分子生物学である.
背景:
- ヘッジホッグ (Hh) 信号伝達経路は,動物の発達に不可欠であり,細胞の成長とパターニングを制御します.
- Hh信号伝達は7つのトランスメブランタンパク質スムートヘンド (Smo) に依存しているが,その調節メカニズムは完全に理解されていない.
研究 の 目的:
- スムージド (Smo) 細胞表面の蓄積と,ヘッジホッグ (Hh) 信号に反応する細胞表面の活性を制御する規制メカニズムを解明する.
- Hh経路の調節におけるタンパク質キナーゼA (PKA) とカゼインキナーゼI (CKI) の役割を調査する.
主な方法:
- ドロソフィラの翼円盤モデルシステムを活用した.
- Smo細胞表面の蓄積とHh経路の活性に対するPKAとCKIの活性調節の影響を調査した.
- サイト固有の変異 (リン酸化欠乏型およびリン酸化模倣型) を通してSmoタンパク質のリン酸化を分析した.
主要な成果:
- PKAとCKIは,Smo細胞表面の蓄積と活動の主な調節因子として特定されました.
- PKAまたはCKIの抑制は,ドロソフィラの翼盤におけるHh誘発のSmo蓄積と経路の活性に障害をもたらします.
- 逆に,PKAの活性が増加すると,Smoの蓄積と経路の活性化が強化された.
- PKAとCKIはSmoを複数の部位で直接リン酸化し,これは細胞表面の局所化とシグナル伝達機能に不可欠である.
- リン酸化が欠けているSmo変異体は,細胞表面に蓄積し,Hh信号を伝達することができなかった.
- 酸化を模倣したSmo変異体は,構成的な細胞表面表現とシグナル伝達を示した.
結論:
- ヘッジホッグ (Hh) 信号は,PKAとCKIによってスムージド (Smo) の漸進的なリン酸化を誘導する.
- このリン酸化イベントは,Smo細胞表面レベルを上昇させ,Hh経路を活性化するために重要です.
- PKAとCKIは,Hhシグナリングカスケードの重要な規制ノードを代表し,Smoの局所化と機能を制御します.
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