RhoAは,p21Waf/Cip1発現を調節するために細胞外信号調節キナーゼの核局所化に影響を与えます

Brian S Zuckerbraun¹, Richard A Shapiro, Timothy R Billiar

¹University of Pittsburgh, Department of Surgery, Pittsburgh, Pa, USA. zuckerbraunbs@msx.upmc.edu

Circulation

|July 23, 2003

まとめ

小型GTPase RhoAは,細胞外信号調節キナーゼ (ERKs) の核の局所化に影響することによって,滑らかな筋肉細胞の増殖に影響を与える. 細胞骨格のRhoA調節がERKに影響する.

科学分野:

細胞生物学細胞生物学
分子シグナリング
滑らかな筋肉の生理学滑らかな筋肉の生理学

背景:

ミトゲン活性化タンパク質キナーゼ (細胞外信号調節キナーゼ,ERKs) は,滑らかな筋肉細胞 (SMC) の細胞サイクル進行を調節する.
小さなGTPase RhoAはERKの活性を調節し,SMCの増殖に影響を与えますが,正確なメカニズムは不明です.
アクチン細胞骨格の調節におけるRhoAの役割と,信号伝達経路におけるその収束は,ERK調節を理解する上で鍵となる.

研究の目的:

RhoAがERKのダウンストリームシグナル伝達とSMCの拡散をどのように調節するかを調査する.
RhoAが細胞骨格の変化と核の局所化を通してERKのシグナル伝達に影響するかどうかを判断する.
細胞骨格であるRhoAと,ERK媒介によるSMCの増殖のメカニズム的関連を解明する.

主な方法:

SMCは,RhoA.を阻害するために,クロストリジア・ボツリンウムC3エクソ酵素で治療されました.
ERKのリン酸化と核の局所化を評価した.
p21Waf1/Cip1の転写とタンパク質レベルを測定しました.
免疫抑制は,リン酸化ERKとアクチン細胞骨格を視覚化するために使用されました.
レプトミシンBは核輸出を抑制し,ERK核の蓄積を誘導するために使用されました.

主要な成果:

RhoAの阻害により,SMCの増殖が減り,p21Waf1/Cip1レベルが上昇し,ERKのリン酸化を阻害することで効果が部分的に逆転した.
RhoAの無効化は,ERKの全体的なリン酸化レベルを変えることなく,リン酸化ERKの核局所化を増加させた.
リン酸化ERKは,C3エキゾエンザイムによって破壊されたアクチン細胞骨格と結合することが判明しました.
核輸出の抑制 (レプトミシンB) もp21Waf1/Cip1レベルを上昇させた.

結論:

RhoAの阻害は,リン酸化されたERKの核レベルを高めます.
RhoAまたは核輸出の抑制は,p21Waf1/Cip1の発現の増加と,部分的にERKに依存したSMCの増殖の減少につながります.
アクチン細胞骨格に対するRhoAの調節は,ERKの細胞下部位化とSMCの増殖への影響を左右する可能性がある.

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