Gauthier SA, Pérez-González R, Sharma A, Huang FK, Alldred MJ, Pawlik M, Kaur G, Ginsberg SD, Neubert TA, Levy E. Enhanced exosome secretion in Down syndrome brain - a protective mechanism to alleviate neuronal endosomal abnormalities.
Acta Neuropathol Commun 2017;
5:65. [PMID:
28851452 PMCID:
PMC5576289 DOI:
10.1186/s40478-017-0466-0]
[Citation(s) in RCA: 76] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2017] [Accepted: 08/17/2017] [Indexed: 12/18/2022] Open
Abstract
A dysfunctional endosomal pathway and abnormally enlarged early endosomes in neurons are an early characteristic of Down syndrome (DS) and Alzheimer's disease (AD). We have hypothesized that endosomal material can be released by endosomal multivesicular bodies (MVBs) into the extracellular space via exosomes to relieve neurons of accumulated endosomal contents when endosomal pathway function is compromised. Supporting this, we found that exosome secretion is enhanced in the brains of DS patients and a mouse model of the disease, and by DS fibroblasts. Furthermore, increased levels of the tetraspanin CD63, a regulator of exosome biogenesis, were observed in DS brains. Importantly, CD63 knockdown diminished exosome release and worsened endosomal pathology in DS fibroblasts. Taken together, these data suggest that increased CD63 expression enhances exosome release as an endogenous mechanism mitigating endosomal abnormalities in DS. Thus, the upregulation of exosome release represents a potential therapeutic goal for neurodegenerative disorders with endosomal pathology.
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