Browsing by Author "De Pace, Raffaella"

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    Clathrin adaptor AP-1-mediated Golgi export of amyloid precursor protein is crucial for the production of neurotoxic amyloid fragments
    (2022) Januario, Yunan C.; Eden, Jessica; de Oliveira, Luan S.; De Pace, Raffaella; Tavares, Lucas A.; da Silva-Januario, Mara E.; Apolloni, Vinicius B.; Wilby, Elise L.; Altmeyer, Randolf; Burgos, Patricia, V; Correa, Sonia A. L.; Gershlick, David C.; daSilva, Luis L. P.
    One of the hallmarks of Alzheimer's disease is the accumulation of toxic amyloid-beta (A beta) peptides in extracellular plaques. The direct precursor of A beta is the carboxyl-terminal fragment beta (or C99) of the amyloid precursor protein (APP). C99 is detected at elevated levels in Alzheimer's disease brains, and its intracellular accumulation has been linked to early neurotoxicity independently of A beta. Despite this, the causes of increased C99 levels are poorly understood. Here, we demonstrate that APP interacts with the clathrin vesicle adaptor AP-1 (adaptor protein 1), and we map the interaction sites on both proteins. Using quantitative kinetic trafficking assays, established cell lines and primary neurons, we also show that this interaction is required for the transport of APP from the trans-Golgi network to endosomes. In addition, disrupting AP-1-mediated transport of APP alters APP processing and degradation, ultimately leading to increased C99 production and A beta release. Our results indicate that AP-1 regulates the subcellular distribution of APP, altering its processing into neurotoxic fragments.
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    The Reelin receptor ApoER2 is a cargo for the adaptor protein complex AP-4: Implications for Hereditary Spastic Paraplegia
    (2024) Caracci, Mario O.; Pizarro, Hector; Alarcon-Godoy, Carlos; Fuentealba, Luz M.; Farfan, Pamela; De Pace, Raffaella; Santibanez, Natacha; Cavieres, Viviana A.; Pastor, Tammy P.; Bonifacino, Juan S.; Mardones, Gonzalo A.; Marzolo, Maria-Paz
    Adaptor protein complex 4 (AP-4) is a heterotetrameric complex that promotes export of selected cargo proteins from the trans-Golgi network. Mutations in each of the AP-4 subunits cause a complicated form of Hereditary Spastic Paraplegia (HSP). Herein, we report that ApoER2, a receptor in the Reelin signaling pathway, is a cargo of the AP-4 complex. We identify the motif ISSF/Y within the ApoER2 cytosolic domain as necessary for interaction with the canonical signal-binding pocket of the mu 4 (AP4M1) subunit of AP-4. AP4E1- knock-out (KO) HeLa cells and hippocampal neurons from Ap4e1-KO mice display increased co-localization of ApoER2 with Golgi markers. Furthermore, hippocampal neurons from Ap4e1-KO mice and AP4M1-KO human iPSC-derived cortical i3Neurons exhibit reduced ApoER2 protein expression. Analyses of biosynthetic transport of ApoER2 reveal differential post -Golgi trafficking of the receptor, with lower axonal distribution in KO compared to wild -type neurons, indicating a role of AP-4 and the ISSF/Y motif in the axonal localization of ApoER2. Finally, analyses of Reelin signaling in mouse hippocampal and human cortical KO neurons show that AP4 deficiency causes no changes in Reelin-dependent activation of the AKT pathway and only mild changes in Reelin-induced dendritic arborization, but reduces Reelin-induced ERK phosphorylation, CREB activation, and Golgi deployment. This work thus establishes ApoER2 as a novel cargo of the AP-4 complex, suggesting that defects in the trafficking of this receptor and in the Reelin signaling pathway could contribute to the pathogenesis of HSP caused by mutations in AP-4 subunits.