Regulation of the SHP-2 tyrosine phosphatase by a novel cholesterol- and cell confluence-dependent mechanism
Regulation of the SHP-2 tyrosine phosphatase by a novel cholesterol- and cell confluence-dependent mechanism
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DOI：
10.1074/jbc.m210701200
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发表时间：
2003-05-16
影响因子：
4.8
通讯作者：
Shpetner, HS
中科院分区：
文献类型：
--
作者：
Burkart, A;Samii, B;Shpetner, HS
接近汇合的内皮细胞表现出受体酪氨酸激酶和粘附连接蛋白的酪氨酸磷酸化显著降低，这是细胞周期停滞和粘附连接稳定所需的。最近，我们证明了内皮细胞膜胆固醇和粘附连接蛋白酪氨酸磷酸化之间的密切相关性。在这里，我们探讨这种相关性的机械基础。我们发现，随着内皮细胞达到汇合，酪氨酸磷酸酶SHP-2被招募到一个低密度的膜部分在胆固醇依赖性的方式。磷酸苯酯不能消除SHP-2与该组分的结合，这强烈表明这种结合是由SHP-2的SH 2结构域以外的其他区域介导的。膜联蛋白II，以前参与胆固醇运输，与SHP-2的复合物，和两种蛋白定位于融合的内皮细胞单层的粘附带。这些研究揭示了一种新的，胆固醇依赖性的机制，通过其与膜联蛋白II的相互作用的信号蛋白的招聘到特定的质膜结构域。
Endothelial cells approaching confluence exhibit marked decreases in tyrosine phosphorylation of receptor tyrosine kinases and adherens junctions proteins, required for cell cycle arrest and adherens junctions stability. Recently, we demonstrated a close correlation in endothelial cells between membrane cholesterol and tyrosine phosphorylation of adherens junctions proteins. Here, we probe the mechanistic basis for this correlation. We find that as endothelial cells reach confluence, the tyrosine phosphatase SHP-2 is recruited to a low-density membrane fraction in a cholesterol-dependent manner. Binding of SHP-2 to this fraction was not abolished by phenyl phosphate, strongly suggesting that this binding was mediated by other regions of SHP-2 beside its SH2 domains. Annexin II, previously implicated in cholesterol trafficking, was associated in a complex with SHP-2, and both proteins localized to adhesion bands in confluent endothelial monolayers. These studies reveal a novel, cholesterol-dependent mechanism for the recruitment of signaling proteins to specific plasma membrane domains via their interactions with annexin II.