Abnormalities of the endosomal-lysosomal system occur in Alzheimer's disease (AD). Relatively little is known about multivesicular endosomes and their contributions to AD pathogenesis and maintenance of neuronal homeostasis, including exosome biogenesis and function. Our preliminary findings suggest that endosomal-lysosomal system dysfunction in AD, which prevents efficient transport and degradation of substrates, can be compensated for by enhanced secretion of exosomes containing neuroprotective factors along with toxic proteins.
In Aim 1 we will determine whether endosomal dysfunction (examined in Projects 1 and 4) and autophagic dysfunction (Project 2) affect exosome generation and secretion in mouse disease models.
In Aim 2, using in vivo and in vitro models, we will study the effects of enhancing or inhibiting lysosomal system function on exosome secretion and the reciprocal effects of enhancing or inhibiting exosome generation on AD-related lysosomal pathology. We demonstrated that cystatin C (CysC) can induce beneficial autophagic and lysosomal degradation and can also enhance exosomal secretion, resulting in neuroprotection. Both extracellular soluble human CysC and exogenous exosomes containing CysC protect cells from death. We propose that CysC can regulate whether proteins are directed to autophagic vesicles for lysosomal degradation or for release into the extracellular space via exosomes, and that both pathways potentially rescue deleterious effects of AD-related dysfunctions of the lysosomal system.
In Aim 3 we will test this hypothesis, demonstrating that reduced CysC levels, which are associated with AD, deprive cells of the protection provided by both soluble CysC and CysC-loaded exosomes. We will further determine whether therapeutic strategies that restore or enhance CysC activity will attenuate AD pathologies. Exosomal membrane-encased proteins are more stable than soluble proteins in the extracellular environment, offering long-lived and potentially spatially distant neuroprotective effects. Thus, exosomes released from cells in the central nervous system may have important protective functions, and CysC-loaded exosomes are a potential therapeutic strategy for the treatment of AD and other neurodegenerative disorders.

Public Health Relevance

Mechanisms to eliminate toxic material are essential for cellular survival and fail In Alzheimer's disease. We will study how enhancing the secretion of exosomes, a recently identified vesicular pathway for releasing toxic material from the cell, might alleviate brain abnormalities and whether exosomes loaded with the protective protein cystatin C represent a novel therapeutic strategy for the treatment of neurodegenerative disorders.

National Institute of Health (NIH)
National Institute on Aging (NIA)
Research Program Projects (P01)
Project #
Application #
Study Section
Special Emphasis Panel (ZAG1-ZIJ-6)
Project Start
Project End
Budget Start
Budget End
Support Year
Fiscal Year
Total Cost
Indirect Cost
Nathan Kline Institute for Psychiatric Research
United States
Zip Code
Alldred, Melissa J; Chao, Helen M; Lee, Sang Han et al. (2018) CA1 pyramidal neuron gene expression mosaics in the Ts65Dn murine model of Down syndrome and Alzheimer's disease following maternal choline supplementation. Hippocampus 28:251-268
Jeanneteau, Freddy; Barrère, Christian; Vos, Mariska et al. (2018) The Stress-Induced Transcription Factor NR4A1 Adjusts Mitochondrial Function and Synapse Number in Prefrontal Cortex. J Neurosci 38:1335-1350
Peng, Katherine Y; Pérez-González, Rocío; Alldred, Melissa J et al. (2018) Apolipoprotein E4 genotype compromises brain exosome production. Brain :
Ginsberg, Stephen D; Alldred, Melissa J; Gunnam, Satya M et al. (2018) Expression profiling suggests microglial impairment in human immunodeficiency virus neuropathogenesis. Ann Neurol 83:406-417
Tiernan, Chelsea T; Ginsberg, Stephen D; He, Bin et al. (2018) Pretangle pathology within cholinergic nucleus basalis neurons coincides with neurotrophic and neurotransmitter receptor gene dysregulation during the progression of Alzheimer's disease. Neurobiol Dis 117:125-136
Kaur, Gurjinder; Gauthier, Sebastien A; Perez-Gonzalez, Rocio et al. (2018) Cystatin C prevents neuronal loss and behavioral deficits via the endosomal pathway in a mouse model of down syndrome. Neurobiol Dis 120:165-173
Colacurcio, Daniel J; Pensalfini, Anna; Jiang, Ying et al. (2018) Dysfunction of autophagy and endosomal-lysosomal pathways: Roles in pathogenesis of Down syndrome and Alzheimer's Disease. Free Radic Biol Med 114:40-51
Pacheco-Quinto, Javier; Clausen, Dana; Pérez-González, Rocío et al. (2018) Intracellular metalloprotease activity controls intraneuronal A? aggregation and limits secretion of A? via exosomes. FASEB J :fj201801319R
East, Brett S; Fleming, Gloria; Peng, Kathy et al. (2018) Human Apolipoprotein E Genotype Differentially Affects Olfactory Behavior and Sensory Physiology in Mice. Neuroscience 380:103-110
Lee, Ju-Hyun; Rao, Mala V; Yang, Dun-Sheng et al. (2018) Transgenic expression of a ratiometric autophagy probe specifically in neurons enables the interrogation of brain autophagy in vivo. Autophagy :1-15

Showing the most recent 10 out of 163 publications