Zambrano N, Bruni P, Minopoli G, Mosca R, Molino D, Russo C, Schettini G, Sudol M, Russo T
Dipartimento di Biochimica e Biotecnologie Mediche, Università di Napoli Federico II, I-80131 Napoli, Italy.
J Biol Chem. 2001 Jun 8;276(23):19787-92. doi: 10.1074/jbc.M100792200. Epub 2001 Feb 21.
The cytosolic domain of the beta-amyloid precursor protein APP interacts with three PTB (phosphotyrosine binding domain)-containing adaptor proteins, Fe65, X11, and mDab1. Through these adaptors, other molecules can be recruited at the cytodomain of APP; one of them is Mena, that binds to the WW domain (a protein module with two conserved tryptophans) of Fe65. The enabled and disabled genes of Drosophila, homologues of the mammalian Mena and mDab1 genes, respectively, are genetic modulators of the phenotype observed in flies null for the Abl tyrosine kinase gene. The involvement of Mena and mDab1 in the APP-centered protein-protein interaction network suggests the possibility that Abl plays a role in APP biology. We show that Fe65, through its WW domain, binds in vitro and in vivo the active form of Abl. Furthermore, in cells expressing the active form of Abl, APP is tyrosine-phosphorylated. Phosphopeptide analysis and site-directed mutagenesis support the hypothesis that Tyr(682) of APP(695) is the target of this phosphorylation. Co-immunoprecipitation experiments demonstrate that active Abl and tyrosine-phosphorylated APP also form a stable complex, which could result from the interaction of the pYENP motif of the APP cytodomain with the SH2 domain of Abl. These results suggest that Abl, Mena, and mDab1 are involved in a common molecular machinery and that APP can play a role in tyrosine kinase-mediated signaling.
β-淀粉样前体蛋白APP的胞质结构域与三种含PTB（磷酸酪氨酸结合结构域）的衔接蛋白Fe65、X11和mDab1相互作用。通过这些衔接蛋白，其他分子可在APP的胞质结构域被招募；其中之一是Mena，它与Fe65的WW结构域（具有两个保守色氨酸的蛋白质模块）结合。果蝇的enabled和disabled基因分别是哺乳动物Mena和mDab1基因的同源物，它们是在Abl酪氨酸激酶基因缺失的果蝇中观察到的表型的遗传调节因子。Mena和mDab1参与以APP为中心的蛋白质-蛋白质相互作用网络，这表明Abl在APP生物学中发挥作用的可能性。我们发现，Fe65通过其WW结构域在体外和体内与Abl的活性形式结合。此外，在表达Abl活性形式的细胞中，APP发生酪氨酸磷酸化。磷酸肽分析和定点诱变支持以下假说：APP(695)的Tyr(682)是这种磷酸化的靶点。免疫共沉淀实验表明，活性Abl和酪氨酸磷酸化的APP也形成稳定复合物，这可能是由于APP胞质结构域的pYENP基序与Abl的SH2结构域相互作用所致。这些结果表明，Abl、Mena和mDab1参与一个共同的分子机制，并且APP可能在酪氨酸激酶介导的信号传导中发挥作用。
