Incorporation of amyloid precursor protein into multivesicular bodies is mediated by TSG101 and Rab27a

CAVIERES, VIVIANA; BUSTAMANTE, HIANARA; GONZALEZ, ALEXIS; OSTROWSKI, MATIAS; MARDONES, GONZALO; BURGOS, PATRICIA

Puerto Varas

Congreso; Reunión anual de Biología Celular Chilena; 2013

Sociedad Chilena de Biologia Celular

Introduction: It has been proposed that amyloid precursor protein (APP) levels contribute to Aβ production and amyloid plaque formation. Recent evidences have shown that APP is located into multivesicular bodies (MVBs), however is unclear if this localization is linked with its lysosomal degradation or secretion through exosomes. To get insights about possible molecular players that could contribute to the incorporation of APP into these pathways, we investigate the involvement of TSG101, an ESCRT component that participate in the biogenesis of intraluminal vesicles (ILVs) containing within MVBs, and Rab27a which plays a crucial role in the formation of exosomes. Material and methods: A stable neuroglioma cell line (H4) expressing APP fused to GFP was depleted of TSG101 by RNAi technique. For Rab27a depletion, APP-expressing cells were infected with lentiviral particles encoding a specific shRNA followed by selection with puromycin. These cells were used to study the levels of APP by immunoblot, FACS analysis and microscopy. Results: Depletion of TSG101 and Rab27a lead to a strong accumulation of APP in intracellular compartments positive to CD63 and Hrs. Moreover, we observed that accumulation of APP under these conditions seems to enhance its amyloidogenic proteolytic processing. Discussion: We propose that a disruption in the incorporation of APP into ILVs can facilitate amyloidogenic processing of APP by an increase in substrate availability.