Rho-dependent Rho kinase activation increases CD44 surface expression and bone resorption in osteoclasts
Rho-dependent Rho kinase activation increases CD44 surface expression and bone resorption in osteoclasts
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DOI：
10.1074/jbc.m211074200
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发表时间：
2003-08-01
影响因子：
4.8
通讯作者：
Hruska, KA
中科院分区：
文献类型：
--
作者：
Chellaiah, MA;Biswas, RS;Hruska, KA
来自骨桥蛋白有效小鼠的破骨细胞表现出降低的CD 44表面表达。骨桥蛋白（OPN）/α（v）β（3）产生的Rho信号通路是CD 44表面表达所必需的。在这项工作中，我们显示Rho效应，Rho激酶（ROK-α），是一个有效的激活剂的CD 44表面表达。ROK-alpha激活与自身磷酸化相关，导致其易位至质膜，以及与CD 44相关。ROK-alpha通过CD 44和ezrin-radixin-moesin（ERM）蛋白的磷酸化和CD44.ERM.actin复合物的形成促进CD 44表面表达。与野生型破骨细胞相比，OPN-/-小鼠的破骨细胞表现出ROK-α磷酸化基础水平降低了55 -60%。此外，Rho（瓦尔-14）转导在刺激这些破骨细胞中的ROK-α/CD 44磷酸化以及CD 44表面表达方面仅部分有效。通过C3转移酶抑制Rho或通过特异性抑制剂Y-27632抑制ROK-alpha的研究显示，ROK-alpha和CD 44表面表达介导的磷酸化减少。α（v）、β（3）或CD 44的中和抗体抑制野生型破骨细胞的迁移和骨吸收。然而，只有抗α（v）或β（3）抗体阻断了OPN诱导的ROK-α、CD 44和ERM蛋白的磷酸化。我们的结果强烈表明ROK-alpha在alpha（v）beta（3）介导的Rho信号传导中的作用，这是磷酸化事件和CD 44表面表达所必需的。由于缺乏OPN而导致的Rho效应器的功能缺陷与CD 44表面表达降低和OPN-/-破骨细胞的低运动性相关。最后，我们发现α（v）β（3）和CD 44之间存在协同作用，促进破骨细胞运动和骨吸收。
Osteoclasts from osteopontin-efficient mice exhibit decreased CD44 surface expression. Osteopontin (OPN)/alpha(v)beta(3) generated Rho signaling pathway is required for the surface expression of CD44. In this work we show the Rho effector, Rho kinase (ROK-alpha), to be a potent activator of CD44 surface expression. ROK-alpha activation was associated with autophosphorylation, leading to its translocation to the plasma membrane, as well as its association with CD44. ROK-alpha promoted CD44 surface expression through phosphorylation of CD44 and ezrin-radixin-moesin (ERM) proteins and CD44.ERM.actin complex formation. Osteoclasts from OPN-/- mice exhibited an similar to55-60% decrease in basal level ROK-alpha phosphorylation as compared with wild type osteoclasts. Furthermore, Rho(Val-14) transduction was only partially effective in stimulating ROK-alpha/CD44 phosphorylation, as well as CD44 surface expression, in these osteoclasts. Studies on the inhibition of Rho by C3 transferase or ROK-alpha by the specific inhibitor, Y-27632, showed a decrease in the phosphorylation mediated by ROK-alpha and CD44 surface expression. Neutralizing antibodies to alpha(v), beta(3), or CD44 inhibited the migration and bone resorption of wild type osteoclasts. However, only anti-alpha(v) or -beta(3) antibodies blocked OPN-induced phosphorylation of ROK-alpha, CD44, and the ERM proteins. Our results strongly suggest a role for ROK-alpha in alpha(v)beta(3)-mediated Rho signaling, which is required for the phosphorylation events and CD44 surface expression. The functional deficiencies in the Rho effector(s) because of the lack of OPN were associated with decreased CD44 surface expression and hypomotility in the OPN-/- osteoclasts. Finally, we find that cooperativity exists between alpha(v)beta(3) and CD44 for osteoclast motility and bone resorption.