Fyn modulation of dab1 effects on amyloid precursor protein and ApoE receptor 2 processing
Fyn modulation of dab1 effects on amyloid precursor protein and ApoE receptor 2 processing
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DOI：
10.1074/jbc.m704140200
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发表时间：
2008-03-07
影响因子：
4.8
通讯作者：
Rebeck, G. William
中科院分区：
文献类型：
--
作者：
Hoe, Hyang-Sook;Minami, S. Sakura;Rebeck, G. William
Dab1是一种细胞内接头蛋白，与淀粉样蛋白前体蛋白（APP）和载脂蛋白e受体2 （apoEr2）相互作用，增加它们在细胞表面的水平，并通过α分泌酶增加它们的裂解。为了研究APP和apoEr2加工和运输过程中这些变化的机制，我们研究了Fyn的作用，Fyn是一种Src家族酪氨酸激酶，已知与Dab1相互作用并磷酸化Dab1。共免疫沉淀、共免疫染色和荧光寿命成像显示了Fyn和APP之间的关联。Fyn诱导APP在(YENPTY762)-Y-757基序tyr1 -757位点磷酸化，并增加APP的细胞表面表达。单独过表达Fyn不会改变sAPP α或细胞质c端片段的水平，尽管它会显著降低A β的产生。然而，在Dab1存在的情况下，Fyn显著增加了sAPP α和c端片段。fyn诱导的APP磷酸化和Dab1的存在增强了APP的细胞表面水平。Fyn还诱导apoEr2磷酸化并增加其细胞表面水平，并且在Dab1存在的情况下，影响其c端片段的加工。体内研究表明，在Fyn敲除中，sAPP α减少，支持Fyn在APP加工中的作用。这些数据表明，部分由于Fyn对Dab1的影响，Fyn调节了APP和apoEr2的磷酸化、转运和加工。
Dab1 is an intracellular adaptor protein that interacts with amyloid precursor protein (APP) and apoE receptor 2 (apoEr2), increases their levels on the cell surface, and increases their cleavage by alpha-secretases. To investigate the mechanism underlying these alterations in processing and trafficking of APP and apoEr2, we examined the effect of Fyn, an Src family-tyrosine kinase known to interact with and phosphorylate Dab1. Co-immunoprecipitation, co-immunostaining, and fluorescence lifetime imaging demonstrated an association between Fyn and APP. Fyn induced phosphorylation of APP at Tyr-757 of the (YENPTY762)-Y-757 motif and increased cell surface expression of APP. Overexpression of Fyn alone did not alter levels of sAPP alpha or cytoplasmic C-terminal fragments, although it significantly decreased production of A beta. However, in the presence of Dab1, Fyn significantly increased sAPP alpha and C-terminal fragments. Fyn-induced APP phosphorylation and cell surface levels of APP were potentiated in the presence of Dab1. Fyn also induced phosphorylation of apoEr2 and increased its cell surface levels and, in the presence of Dab1, affected processing of its C-terminal fragment. In vivo studies showed that sAPP alpha was decreased in the Fyn knock-out, supporting a role for Fyn in APP processing. These data demonstrate that Fyn, due in part to its effects on Dab1, regulates the phosphorylation, trafficking, and processing of APP and apoEr2.