β3 integrin phosphorylation is essential for Arp3 organization into leukocyte αvβ3-vitronectin adhesion contacts
β3 integrin phosphorylation is essential for Arp3 organization into leukocyte αvβ3-vitronectin adhesion contacts
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DOI：
10.1242/jcs.00987
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发表时间：
2004-03-15
影响因子：
4
通讯作者：
Blystone, SD
中科院分区：
文献类型：
--
作者：
Chandhoke, SK;Williams, M;Blystone, SD
整合素在自我调节造血粘附和迁移中起关键作用。白细胞β 3整合素介导的与玻连蛋白的粘附需要蛋白激酶C激活和β 3胞质尾酪氨酸747的磷酸化。我们以前已经表明，β（3）磷酸化是Rho激活所必需的。在这项研究中，磷酸化β（3）酪氨酸747特异性抗体用于定位玻连蛋白粘附结构中的磷酸化β（3）。含有磷酸化β（3）的早期粘附接触先于肌动蛋白应力纤维形成。β 3磷酸化在整个粘附过程中逐渐降低，与肌动蛋白应力纤维的出现一致。在类似的粘附结构中，观察到β（3）与酪氨酸402磷酸化Pyk2的共定位的时间依赖性增加，为下游信号复合物的形成提供了证据。令人惊讶的是，Arp3在表达野生型β 3的细胞中组织成类似的粘附接触，但在表达β 3的不可磷酸化突变体的细胞中却没有，这表明β 3磷酸化是Arp3与粘附复合物螯合所必需的。通过Rho激酶抑制剂抑制肌动蛋白应力纤维的形成，破坏了Arp3的组织，同时延长了整个粘附时间过程中的β 3磷酸化。这些数据证实了β 3磷酸化在β 3介导的与玻连蛋白的粘附中的需要，并表明β 3磷酸化允许在白细胞中肌动蛋白应力纤维形成所必需的粘附位点处的信号复合物组装。
Integrins play a pivotal role in self-regulated hematopoietic adhesion and migration. Leukocyte alphanubeta(3) integrin-mediated adhesion to vitronectin requires protein kinase C activation and phosphorylation on tyrosine 747 of the beta(3) cytoplasmic tail. We have previously shown that beta(3) phosphorylation is required for Rho activation. In this study, an antibody specific to phosphorylated beta(3) tyrosine 747 was used to localize phosphorylated alphanubeta(3) in vitronectin adhesive structures. Early adhesion contacts containing phosphorylated beta(3) preceded actin stress fiber formation. beta(3) phosphorylation decreased progressively throughout the course of adhesion coincident with the appearance of actin stress fibers. Time-dependent increases in colocalization of beta(3) with tyrosine 402 phosphorylated Pyk2 in similar adhesive structures was observed, providing evidence for downstream signaling complex formation. Surprisingly, Arp3 organized into similar adhesion contacts in cells expressing wild-type beta(3) but not in those expressing a nonphosphorylatable mutant of beta(3), suggesting that beta(3) phosphorylation is required for sequestration of Arp3 to adhesion complexes. Suppression of actin stress fiber formation by an inhibitor to Rho kinase disrupted Arp3 organization while prolonging beta(3) phosphorylation throughout the adhesion time course. These data confirm a requirement for beta(3) phosphorylation in alphanubeta(3)-mediated adhesion to vitronectin and suggest that beta(3) phosphorylation permits signaling complex assembly at the adhesion site necessary for actin stress fiber formation in leukocytes.