Adaptor Protein LRAP25 Mediates Myotonic Dystrophy Kinase-related Cdc42-binding Kinase (MRCK) Regulation of LIMK1 Protein in Lamellipodial F-actin Dynamics
Adaptor Protein LRAP25 Mediates Myotonic Dystrophy Kinase-related Cdc42-binding Kinase (MRCK) Regulation of LIMK1 Protein in Lamellipodial F-actin Dynamics
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DOI：
10.1074/jbc.m114.588079
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发表时间：
2014-09-26
影响因子：
4.8
通讯作者：
Tan, Ivan
中科院分区：
文献类型：
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作者：
Lee, Irene Cheng Jie;Leung, Thomas;Tan, Ivan
强直性肌营养不良激酶相关Cdc 42结合激酶（MRCK）已被证明通过与衔接蛋白亮氨酸重复衔接蛋白35 a（LRAP 35 a）的相互作用定位于哺乳动物细胞的板层，亮氨酸重复衔接蛋白35 a将其与肌球蛋白18 A（MYO 18 A）连接以激活细胞迁移所必需的板层肌动球蛋白网络。在这里，我们报告的另一个接头蛋白LRAP 25介导的MRCK协会与LIM激酶1（LIMK 1）的鉴定。位于板状伪足的LRAP 25-MRCK复合物对于调节局部LIMK 1及其下游F-肌动蛋白调节因子cofilin是必不可少的。在功能上，MRCK或LRAP 25的抑制导致LIMK 1活性的显著抑制和对B16-F1细胞中氟化铝诱导的cofilin磷酸化的下调，这最终导致板状脂质体F-肌动蛋白的失调和细胞骨架结构的重组，从而导致细胞极化和运动性的缺陷。因此，这些生物化学和功能表征强调了LRAP 25-MRCK复合物在LIMK 1-cofilin信号传导中的功能相关性以及LRAP衔接子作为MRCK细胞定位和下游特异性的关键决定因素的重要性。
Myotonic dystrophy kinase-related Cdc42-binding kinase (MRCK) has been shown to localize to the lamella of mammalian cells through its interaction with an adaptor protein, leucine repeat adaptor protein 35a (LRAP35a), which links it with myosin 18A (MYO18A) for activation of the lamellar actomyosin network essential for cell migration. Here, we report the identification of another adaptor protein LRAP25 that mediates MRCK association with LIM kinase 1 (LIMK1). The lamellipodium-localized LRAP25-MRCK complex is essential for the regulation of local LIMK1 and its downstream F-actin regulatory factor cofilin. Functionally, inhibition of either MRCK or LRAP25 resulted in a marked suppression of LIMK1 activity and down-regulation of cofilin phosphorylation in response to aluminum fluoride induction in B16-F1 cells, which eventually resulted in deregulation of lamellipodial F-actin and reorganization of cytoskeletal structures causing defects in cell polarization and motility. These biochemical and functional characterizations thus underline the functional relevance of the LRAP25-MRCK complex in LIMK1-cofilin signaling and the importance of LRAP adaptors as key determinants of MRCK cellular localization and downstream specificities.