Numerous studies have shown that Alpha-beta accumulation leads to synaptic dysfunction and loss of synapses. Synaptic Alpha-beta and Alpha-beta oligomers have been strongly implicated in the progression of AD. Recent studies have demonstrated that gamma-secretase forms an active complex at synapses. However, proteins modulating synaptic APP processing remain largely unknown. We have performed two proteomic screens in mouse brain lysates to identify proteins interacting with the ectodomains of APP and nicastrin. These screens have identified synaptotagmins (Syt) 1, 2, and 9 as strong binding partners of both APP and nicastrin. Syt1 and 9 also interact with the large loop of PSI (Project 3). Sytl, 2, and 9 are type I Ca2+-sensing synaptic vesicle membrane proteins and play a major role in distinct membrane fusion events for synaptic vesicle release. Our further co-IP, EM, and in situ PLA studies demonstrated that full-length Syts bind to APP in cells and mouse brains. GST pulldown assays confirmed specific binding of Sytl to a the region surrounding the KPI domain of APP. Our preliminary data also show that overexpression of Syts increases Alpha-beta generation and ratios, by perhaps inducing p- and/or gamma-secretase-mediated processing of APP. Syt expression also increases palmitoylated APP levels. Here, we will test the hypothesis that Sytl, 2, and 9 act as physiological modulators of APP processing in neurons. Specifically, we will further explore the regulation of Syt binding to APP, dissect the contribution of Syts to Alpha-beta generation in neuronal models and will ask whether Syts affect the neuronal functions of gamma-secretase. In addition, we will also analyze the effect of novel APP-specific gamma-secretase inhibitors (Project 1) and gamma-secretase modulators (Project 2) on the neuronal functions of gamma-secretase with particular focus on synaptic proteins, and on the processing of non-APP gamma-secretase substrates. These experiments are aimed at identifying compounds lacking adverse effects commonly associated with gamma-secretase inhibitors. Our project will contribute to the overall goal of the program project in providing mechanistic data that may serve in the development of novel p- or gamma-secretase-based strategies forthe prevention and treatment of Alzheimer's disease.

Public Health Relevance

We have recently found that three synaptotagmins bind to the beta-amyloid precursor protein, thereby increasing toxic beta-amyloid production. This proposal directly tests the mechanism of how synaptotagmins modulate beta-amyloid generation in neuronal models of Alzheimer's disease and may contribute to the development of novel strategies for the prevention and treatment of the disease.

Agency
National Institute of Health (NIH)
Institute
National Institute on Aging (NIA)
Type
Research Program Projects (P01)
Project #
5P01AG015379-17
Application #
8738551
Study Section
Special Emphasis Panel (ZAG1)
Project Start
Project End
Budget Start
2014-07-01
Budget End
2015-06-30
Support Year
17
Fiscal Year
2014
Total Cost
Indirect Cost
Name
Brigham and Women's Hospital
Department
Type
DUNS #
City
Boston
State
MA
Country
United States
Zip Code
02199
Zoltowska, Katarzyna Marta; Berezovska, Oksana (2017) Dynamic Nature of presenilin1/?-Secretase: Implication for Alzheimer's Disease Pathogenesis. Mol Neurobiol :
Gong, Yi; Sasidharan, Nikhil; Laheji, Fiza et al. (2017) Microglial dysfunction as a key pathological change in adrenomyeloneuropathy. Ann Neurol 82:813-827
Kara, Eleanna; Marks, Jordan D; Fan, Zhanyun et al. (2017) Isoform- and cell type-specific structure of apolipoprotein E lipoparticles as revealed by a novel Forster resonance energy transfer assay. J Biol Chem 292:14720-14729
Raven, Frank; Ward, Joseph F; Zoltowska, Katarzyna M et al. (2017) Soluble Gamma-secretase Modulators Attenuate Alzheimer's ?-amyloid Pathology and Induce Conformational Changes in Presenilin 1. EBioMedicine 24:93-101
Wagner, Steven L; Rynearson, Kevin D; Duddy, Steven K et al. (2017) Pharmacological and Toxicological Properties of the Potent Oral ?-Secretase Modulator BPN-15606. J Pharmacol Exp Ther 362:31-44
Yang, Ting; Li, Shaomin; Xu, Huixin et al. (2017) Large Soluble Oligomers of Amyloid ?-Protein from Alzheimer Brain Are Far Less Neuroactive Than the Smaller Oligomers to Which They Dissociate. J Neurosci 37:152-163
Ward, Joseph; Wang, Haizhi; Saunders, Aleister J et al. (2017) Mechanisms that synergistically regulate ?-secretase processing of APP and A?-? protein levels: relevance to pathogenesis and treatment of Alzheimer's disease. Discov Med 23:121-128
Zoltowska, Katarzyna Marta; Maesako, Masato; Lushnikova, Iryna et al. (2017) Dynamic presenilin 1 and synaptotagmin 1 interaction modulates exocytosis and amyloid ? production. Mol Neurodegener 12:15
Bolduc, D M; Selkoe, D J; Wolfe, M S (2017) Enzymatic Assays for Studying Intramembrane Proteolysis. Methods Enzymol 584:295-308
Williamson, Rebecca L; Laulagnier, Karine; Miranda, André M et al. (2017) Disruption of amyloid precursor protein ubiquitination selectively increases amyloid ? (A?) 40 levels via presenilin 2-mediated cleavage. J Biol Chem 292:19873-19889

Showing the most recent 10 out of 139 publications