細胞表面に発現するTGF-α前駆体は,隣接する細胞のEGF受容体と結合し,信号伝導につながります
S T Wong1, L F Winchell, B K McCune
1Lineberger Cancer Research Center, University of North Carolina School of Medicine, Chapel Hill 27514.
Cell
|February 10, 1989
まとめ
成長因子-アルファ (TGF-alpha) の前駆体形態は,完全に処理されていなくても,隣接する細胞の表皮成長因子 (EGF) 受容体を活性化することができます. この膜に結合したproTGF-alphaは,細胞信号伝達経路に影響を与える生物学的活性を示しています.
科学分野:
- 分子生物学は分子生物学である.
- 細胞シグナル伝達 細胞信号伝達
- がん研究 がん研究
背景:
- 変形成長因子アルファ (TGF-alpha) は,通常,膜に結合した前駆体からタンパク質分解によって放出されます.
- プロテアゼ活動は,特に腫瘍細胞において,TGF-α成熟の速度を制限するステップである.
研究 の 目的:
- プロテオリシス分裂前のTGF-α (proTGF-alpha) の膜結合前駆体形態の生物学的活性を調べる.
- proTGF-alphaが成熟した分泌形態とは独立して生物学的効果を発揮できるかどうかを判断する.
主な方法:
- アミノ酸置換は,発現ベクトル内のTGF-alphaのタンパク質分裂部位に導入されました.
- BHK細胞は,これらの変化した配列で感染し,成熟したTGF-αの分泌を防止しました.
- EGF受容体を発現するBHK細胞,細胞表面のproTGF-alphaを発現するA431細胞で共潜化実験を行った.
主要な成果:
- 感染したBHK細胞は,細胞表面のproTGF-alphaの高いレベルを発現したが,成熟したTGF-alphaを分泌することはなかった.
- 膜に結合するproTGF-alphaは,隣接するA431細胞の表皮成長因子 (EGF) 受容体と結合する.
- この相互作用により,EGF受容体の自己リン酸化が誘発され,A431細胞の細胞内カルシウム濃度が急速に上昇した.
結論:
- TGF-alpha (proTGF-alpha) の膜に結合した前駆体形態は,固有の生物学的活性を持っています.
- ProTGF-alphaは,タンパク質分解処理を必要とせずに,隣接細胞のEGF受容体を直接活性化することができます.
- これらの発見は,成長因子の統合膜前駆体が重要な生物学的な役割を果たす可能性があることを示唆しています.
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