The interactome of the Amyloid betaeta Precursor Protein family members is shaped by phosphorylation of their intracellular domains.

Department of Microbiology and Immunology, Albert Einstein College of Medicine, 1300 Morris Park Ave, Bronx, NY 10461, USA. .
Molecular Neurodegeneration (Impact Factor: 6.56). 08/2009; 4(1):28. DOI: 10.1186/1750-1326-4-28
Source: PubMed


Brain tissue from patients with Alzheimer's disease has shown an increase of phosphorylation of Tyr-682, located on the conserved Y682ENPTY motif, and Thr-668 residues, both in the intracellular domain (AID) of amyloid beta precursor protein (APP), although the role of these two residues is not yet known.
Here, we report that the phosphorylation status of Tyr-682, and in some cases Thr-668, shapes the APP interactome. It creates a docking site for SH2-domain containing proteins, such as ShcA, ShcB, ShcC, Grb7, Grb2, as well as adapter proteins, such as Crk and Nck, that regulate important biological processes, cytosolic tyrosine kinases, such as Abl, Lyn and Src, which regulate signal transduction pathways, and enzymes that control phosphatidylinositols levels and signaling, such as PLC-gamma. At the same time, it either reduces (like for JIP1, NUMB, NUMBL and ARH) or abolishes (like for Fe65, Fe65L1 and Fe65L2) binding of other APP interactors. Phosphorylation of Thr-668, unlike Tyr-682, does not seem to affect APP's ability to interact with the various proteins, with Pin1 and X11 being the exclusions. We also found that there are some differences between the interactions to AID and to ALID1 and ALID2, its two homologues.
Our data indicates that APP can regulate diverse cellular processes and that, vice versa, a network of signaling events can impact APP processing. Our results also suggest that phosphorylation of the APP Intracellular Domain will dramatically shape the APP interactome and, consequently, will regulate APP processing, APP transport and APP/AID-mediated functions.


Available from: Luciano D'adamio
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    • "When Y 682 is phosphorylated, it creates docking sites for cytosolic proteins, such as Shc, Grb2, and Grb7, and inhibits the binding of others, such as the Fe65 family. Differently, when Y 682 is dephosphorylated, the binding of proteins containing a phosphotyrosine-binding (PTB) domain is impaired (Russo et al., 2002; Tarr et al., 2002; Zhou et al., 2004, 2009; Tamayev et al., 2009; Muller and Zheng, 2012). "
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    ABSTRACT: The intracellular transport and localization of amyloid precursor protein (APP) are critical determinants of APP processing and β-amyloid peptide production, thus crucially important for the pathophysiology of Alzheimer’s disease (AD). Notably, the C-terminal Y682ENPTY687 domain of APP binds to specific adaptors controlling APP trafficking and sorting in neurons. Mutation on the Y682 residue to glycine (Y682G) leads to altered APP sorting in hippocampal neurons that favors its accumulation in intracellular compartments and the release of soluble APPα. Such alterations induce premature aging and learning and cognitive deficits in APP Y682G mutant mice (APPYG/YG). Here, we report that Y682G mutation affects formation of the APP complex with sortilin-related receptor (SorLA), resulting in endo-lysosomal dysfunctions and neuronal degeneration. Moreover, disruption of the APP/SorLA complex changes the trafficking pathway of SorLA, with its consequent increase in secretion outside neurons. Mutations in the SorLA gene are a prognostic factor in AD, and increases in SorLA levels in cerebrospinal fluid are predictive of AD in humans. These results might open new possibilities in comprehending the role played by SorLA in its interaction with APP and in the progression of neuronal degeneration. In addition, they further underline the crucial role played by Y682 residue in controlling APP trafficking in neurons.
    Frontiers in Cellular Neuroscience 03/2015; 9. DOI:10.3389/fncel.2015.00109 · 4.29 Impact Factor
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    • "Thus, it is plausible that the NH2-terminal domain of APP may have an intra-lumen function while the COOH-terminus may regulate pre-synaptic vesicle's functions via interaction with proteins expressed on the outer membrane of synaptic vesicles (i.e. the side exposed to the cytosol), the cytosolic pre-synaptic environment and/or the inner side of the pre-synaptic membrane (active zone). In this context it is worth noting that the short APP intracellular region contains motifs that function as docking domains for cytosolic as well as other membrane-bound proteins [39]–[52]. Although intra- and extra-lumen functions of APP may be both important in pre-synaptic vesicles biology, we decided to explore the potential role of the intracellular region of APP because in vivo observations have underlined the key physiological and pathological role of the APP intracellular domain. "
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    ABSTRACT: Amyloid Precursor Protein (APP) is a type I membrane protein that undergoes extensive processing by secretases, including BACE1. Although mutations in APP and genes that regulate processing of APP, such as PSENs and BRI2/ITM2B, cause dementias, the normal function of APP in synaptic transmission, synaptic plasticity and memory formation is poorly understood. To grasp the biochemical mechanisms underlying the function of APP in the central nervous system, it is important to first define the sub-cellular localization of APP in synapses and the synaptic interactome of APP. Using biochemical and electron microscopy approaches, we have found that APP is localized in pre-synaptic vesicles, where it is processed by Bace1. By means of a proteomic approach, we have characterized the synaptic interactome of the APP intracellular domain. We focused on this region of APP because in vivo data underline the central funtional and pathological role of the intracellular domain of APP. Consistent with the expression of APP in pre-synaptic vesicles, the synaptic APP intracellular domain interactome is predominantly constituted by pre-synaptic, rather than post-synaptic, proteins. This pre-synaptic interactome of the APP intracellular domain includes proteins expressed on pre-synaptic vesicles such as the vesicular SNARE Vamp2/Vamp1 and the Ca2+ sensors Synaptotagmin-1/Synaptotagmin-2, and non-vesicular pre-synaptic proteins that regulate exocytosis, endocytosis and recycling of pre-synaptic vesicles, such as target-membrane-SNAREs (Syntaxin-1b, Syntaxin-1a, Snap25 and Snap47), Munc-18, Nsf, α/β/γ-Snaps and complexin. These data are consistent with a functional role for APP, via its carboxyl-terminal domain, in exocytosis, endocytosis and/or recycling of pre-synaptic vesicles.
    PLoS ONE 09/2014; 9(9):e108576. DOI:10.1371/journal.pone.0108576 · 3.23 Impact Factor
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    • "Tyrosine 682 in the Y682ENPTY motif is crucial for the binding of Fe65 and other adaptor proteins. Phosphorylation of this residue by src, abl, trkA, and EGFR tyrosine kinases was reported to enhance the binding of SH2-domain containing adaptor proteins while abolishing binding of Fe65 [34,41-44]. Consequently, our BiFC assay revealed increased nuclear signaling when Tyrosine 682 was mutated to phenylalanine to prevent phosphorylation. "
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    ABSTRACT: The amyloid precursor protein (APP) intracellular domain (AICD) is released from full-length APP upon sequential cleavage by either α- or β-secretase followed by γ-secretase. Together with the adaptor protein Fe65 and the histone acetyltransferase Tip60, AICD forms nuclear multiprotein complexes (AFT complexes) that function in transcriptional regulation. To develop a medium-throughput machine-based assay for visualization and quantification of AFT complex formation in cultured cells. We used cotransfection of bimolecular fluorescence complementation (BiFC) fusion constructs of APP and Tip60 for analysis of subcellular localization by confocal microscopy and quantification by flow cytometry (FC). Our novel BiFC-constructs show a nuclear localization of AFT complexes that is identical to conventional fluorescence-tagged constructs. Production of the BiFC signal is dependent on the adaptor protein Fe65 resulting in fluorescence complementation only after Fe65-mediated nuclear translocation of AICD and interaction with Tip60. We applied the AFT-BiFC system to show that the Swedish APP familial Alzheimer's disease mutation increases AFT complex formation, consistent with the notion that AICD mediated nuclear signaling mainly occurs following APP processing through the amyloidogenic β-secretase pathway. Next, we studied the impact of posttranslational modifications of AICD on AFT complex formation. Mutation of tyrosine 682 in the YENPTY motif of AICD to phenylalanine prevents phosphorylation resulting in increased nuclear AFT-BiFC signals. This is consistent with the negative impact of tyrosine phosphorylation on Fe65 binding to AICD. Finally, we studied the effect of oxidative stress. Our data shows that oxidative stress, at a level that also causes cell death, leads to a reduction in AFT-BiFC signals. We established a new method for visualization and FC quantification of the interaction between AICD, Fe65 and Tip60 in the nucleus based on BiFC. It enables flow cytometric analysis of AICD nuclear signaling and is characterized by scalability and low background fluorescence.
    PLoS ONE 09/2013; 8(9):e76094. DOI:10.1371/journal.pone.0076094 · 3.23 Impact Factor
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