Leng Yan, Zhang Jinyi, Badour Karen, Arpaia Enrico, Freeman Spencer, Cheung Pam, Siu Michael, Siminovitch Katherine
Departments of Medicine, Immunology, Medical Genetics, and Microbiology, University of Toronto and The Samuel Lunenfeld Research Institute, Mount Sinai Hospital, Toronto, ON, Canada M5G 1X5.
Proc Natl Acad Sci U S A. 2005 Jan 25;102(4):1098-103. doi: 10.1073/pnas.0409120102. Epub 2005 Jan 18.
WAVE2 is a member of the Wiskott-Aldrich syndrome protein family of cytoskeletal regulatory proteins shown to link Rac activation to actin remodeling via induction of Arp 2/3 activity. WAVE2 is thought to be regulated by its positioning in a macromolecular complex also containing the Abelson-(Abl) interactor-1 (Abi-1) adaptor, but the molecular basis and biologic relevance of WAVE2 inclusion in this complex are ill defined. Here we show that Abi-1 binding to WAVE2 is mediated by discrete motifs in the Abi-1 coiled-coil and WAVE2 WAVE-homology domains and increases markedly in conjunction with Abi-1-WAVE2 translocation and colocalization at the leading edge in B16F1 cells after fibronectin stimulation. Abi-1 also couples WAVE2 to Abl after cell stimulation, an interaction that triggers Abl membrane translocation with WAVE2, Abi-1, and activated Rac, as well as Abl-mediated tyrosine phosphorylation and WAVE2 activation. By contrast, mutation of tyrosine residue Y150, identified here as the major site of Abl-mediated WAVE2 tyrosine phosphorylation, as well as disruption of WAVE2-Abi-1 binding, impairs induction of WAVE2-driven actin polymerization and its membrane translocation in association with activated Rac. Similarly, WAVE2 tyrosine phosphorylation and induction of membrane actin rearrangement are abrogated in fibroblasts lacking the Abl family kinase. Together, these data reveal that Abi-1-mediated coupling of Abl to WAVE2 promotes Abl-evoked WAVE2 tyrosine phosphorylation required to link WAVE2 with activated Rac and with actin polymerization and remodeling at the cell periphery.
WAVE2是细胞骨架调节蛋白的威斯科特-奥尔德里奇综合征蛋白家族的成员，已证明其通过诱导Arp 2/3活性将Rac激活与肌动蛋白重塑联系起来。WAVE2被认为受其在一个还包含阿贝尔森（Abl）相互作用蛋白1（Abi-1）衔接子的大分子复合物中的定位调节，但WAVE2包含在该复合物中的分子基础和生物学相关性尚不清楚。在这里，我们表明Abi-1与WAVE2的结合由Abi-1卷曲螺旋结构域和WAVE2 WAVE同源结构域中的离散基序介导，并且在纤连蛋白刺激后，B16F1细胞前缘的Abi-1-WAVE2易位和共定位时显著增加。细胞刺激后，Abi-1还将WAVE2与Abl偶联，这种相互作用触发Abl与WAVE2、Abi-1和活化的Rac一起向膜易位，以及Abl介导的酪氨酸磷酸化和WAVE2激活。相比之下，酪氨酸残基Y150（此处确定为Abl介导的WAVE2酪氨酸磷酸化的主要位点）的突变以及WAVE2-Abi-1结合的破坏，损害了WAVE2驱动的肌动蛋白聚合的诱导及其与活化Rac相关的膜易位。同样，在缺乏Abl家族激酶的成纤维细胞中，WAVE2酪氨酸磷酸化和膜肌动蛋白重排的诱导被消除。总之，这些数据表明Abi-1介导的Abl与WAVE2的偶联促进了Abl诱导的WAVE2酪氨酸磷酸化，这是将WAVE2与活化的Rac以及细胞周边的肌动蛋白聚合和重塑联系起来所必需的。
