Amyloid Precursor Protein Dimerization and Synaptogenic Function Depend on Copper Binding to the Growth Factor-Like Domain
Amyloid Precursor Protein Dimerization and Synaptogenic Function Depend on Copper Binding to the Growth Factor-Like Domain
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DOI：
10.1523/jneurosci.0180-14.2014
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发表时间：
2014-08-13
影响因子：
5.3
通讯作者：
Kins, Stefan
中科院分区：
文献类型：
--
作者：
Baumkoetter, Frederik;Schmidt, Nadine;Kins, Stefan
越来越多的证据表明，铜结合淀粉样前体蛋白（APP）具有重要的突触功能。APP突触发生功能依赖于细胞外E1结构域的反式二聚化，包括生长因子样结构域（GFLD）和铜结合结构域（CuBD）。在这里，我们报告的1.75埃的晶体结构的GFLD在复杂的铜离子结合具有高亲和力的扩展发夹环在二聚化界面。在免疫共沉淀试验中，铜结合促进APP相互作用，而GFLD或CuBD的铜结合位点的突变导致APP顺式二聚化的急剧减少。我们表明，铜是必不可少的，足以诱导反式定向二聚纯化APP。此外，原代神经元与HEK 293细胞表达不同的APP突变体的混合培养试验表明，APP有效地促进突触依赖于铜结合GFLD。总之，这些发现表明，铜结合到APP的GFLD是APP顺式/反式定向二聚化和APP突触发生功能所需的。因此，神经元活动或疾病相关的铜稳态变化可能与APP突触功能的改变沿着。
Accumulating evidence suggests that the copper-binding amyloid precursor protein (APP) has an essential synaptic function. APP synaptogenic function depends on trans-directed dimerization of the extracellular E1 domain encompassing a growth factor-like domain (GFLD) and a copper-binding domain (CuBD). Here we report the 1.75 angstrom crystal structure of the GFLD in complex with a copper ion bound with high affinity to an extended hairpin loop at the dimerization interface. In coimmunoprecipitation assays copper binding promotes APP interaction, whereas mutations in the copper-binding sites of either the GFLD or CuBD result in a drastic reduction in APP cis-orientated dimerization. We show that copper is essential and sufficient to induce trans-directed dimerization of purified APP. Furthermore, a mixed culture assay of primary neurons with HEK293 cells expressing different APP mutants revealed that APP potently promotes synaptogenesis depending on copper binding to the GFLD. Together, these findings demonstrate that copper binding to the GFLD of APP is required for APP cis-/trans-directed dimerization and APP synaptogenic function. Thus, neuronal activity or disease-associated changes in copper homeostasis likely go along with altered APP synaptic function.