title: Retromer and Rab2-dependent trafficking mediate PS1 degradation by proteasomes in endocytic disturbance.
abstract: Accumulating evidence suggests that endocytic pathway deficits are involved in Alzheimer's disease pathogenesis. Several reports show that endocytic disturbance affects β-amyloid peptide (Aβ) cleavage from β-amyloid precursor protein (APP). Presenilin-1 (PS1) is the catalytic core of the γ-secretase complex required for Aβ generation. Previously, we showed that aging induces endocytic disturbance, resulting in the accumulation of Aβ and APP in enlarged endosomes. It remains unclear, however, whether PS1 localization and function are affected with endocytic disturbance. Here, we report that in endocytic disturbance, PS1 is transported from endosomes to ER/Golgi compartments via retromer trafficking, and that PS1 interacts with vacuolar protein sorting-associated protein 35 both in vitro and in vivo. Moreover, PS1 is degraded by proteasomes via a Rab2-dependent trafficking pathway, only during endocytic disturbance. These findings suggest that PS1 levels and localization in endosomes are regulated by retromer trafficking and ER-associated degradation system, even if endocytic disturbance significantly induces the endosomal accumulation of APP and β-site APP-cleaving enzyme 1. Results of this study also suggest that retromer deficiency can affect PS1 localization in endosomes, where Aβ cleavage mainly occurs, possibly leading to enhanced Aβ pathology. We proposed the following mechanism for intracellular transport of presenilin-1 (PS1). When endosome/lysosome trafficking is disturbed, PS1 is transported from endosome to endoplasmic reticulum (ER)/Golgi compartments via retromer and Rab2-mediated trafficking, and then degraded by endoplasmic reticulum-associated degradation (ERAD). Perturbations in this trafficking can cause abnormal endosomal accumulation of PS1, and then may lead to exacerbated Aβ pathology. Cover Image for this issue: doi: 10.1111/jnc.13318.
authors.affiliation: Section of Cell Biology and Pathology, Department of Alzheimer's Disease Research, Center for Development of Advanced Medicine for Dementia, National Center for Geriatrics and Gerontology (NCGG), Aichi, Japan.
authors.forename: Naoya
authors.initials: N
authors.lastname: Ueda
authors.affiliation: Laboratory of Neuropathology and Neuroscience, Graduate School of Pharmaceutical Sciences, The University of Tokyo, Tokyo, Japan.
authors.forename: Taisuke
authors.initials: T
authors.lastname: Tomita
authors.affiliation: Section of Cell Biology and Pathology, Department of Alzheimer's Disease Research, Center for Development of Advanced Medicine for Dementia, National Center for Geriatrics and Gerontology (NCGG), Aichi, Japan.
authors.forename: Katsuhiko
authors.initials: K
authors.lastname: Yanagisawa
authors.affiliation: Section of Cell Biology and Pathology, Department of Alzheimer's Disease Research, Center for Development of Advanced Medicine for Dementia, National Center for Geriatrics and Gerontology (NCGG), Aichi, Japan.
authors.forename: Nobuyuki
authors.initials: N
authors.lastname: Kimura
mesh_terms: D000818:Animals; D045744:Cell Line, Tumor; D002478:Cells, Cultured; D004705:Endocytosis / Q000502:physiology*; D004721:Endoplasmic Reticulum / Q000378:metabolism; D005260:Female; D006056:Golgi Apparatus / Q000378:metabolism; D008252:Macaca fascicularis; D051379:Mice; D008810:Mice, Inbred C57BL; D053764:Presenilin-1 / Q000378:metabolism*; D046988:Proteasome Endopeptidase Complex / Q000378:metabolism*; D021381:Protein Transport / Q000502:physiology; D059748:Proteolysis; D051381:Rats; D017207:Rats, Sprague-Dawley; D020693:rab2 GTP-Binding Protein / Q000378:metabolism*
chemical_list: D053764:Presenilin-1; C000607793:Psen1 protein, rat; D046988:Proteasome Endopeptidase Complex; D020693:rab2 GTP-Binding Protein
keywords: Alzheimer's disease; ERAD; endocytosis; presenilin-1; rab2; retromer