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.
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.
|Kuzuya, Akira; Zoltowska, Katarzyna M; Post, Kathryn L et al. (2016) Identification of the novel activity-driven interaction between synaptotagmin 1 and presenilin 1 links calcium, synapse, and amyloid beta. BMC Biol 14:25|
|Bolduc, David M; Montagna, Daniel R; Gu, Yongli et al. (2016) Nicastrin functions to sterically hinder Î³-secretase-substrate interactions driven by substrate transmembrane domain. Proc Natl Acad Sci U S A 113:E509-18|
|Zhang, Jing; Lu, Dai; Wei, Han-Xun et al. (2016) Part 3: Notch-sparing Î³-secretase inhibitors: SAR studies of 2-substituted aminopyridopyrimidinones. Bioorg Med Chem Lett 26:2138-41|
|Leriche, Geoffray; Chen, Allen C; Kim, Sumin et al. (2016) Fluorescent Analogue of Batimastat Enables Imaging of Î±-Secretase in Living Cells. ACS Chem Neurosci 7:40-5|
|Zoltowska, Katarzyna Marta; Maesako, Masato; Berezovska, Oksana (2016) Interrelationship between changes in the amyloid Î² 42/40 ratio and presenilin 1 conformation. Mol Med 22:|
|Bolduc, David M; Montagna, Daniel R; Seghers, Matthew C et al. (2016) The amyloid-beta forming tripeptide cleavage mechanism of Î³-secretase. Elife 5:|
|Wei, Han-Xun; Lu, Dai; Sun, Vivien et al. (2016) Part 2. Notch-sparing Î³-secretase inhibitors: The study of novel Î³-amino naphthyl alcohols. Bioorg Med Chem Lett 26:2133-7|
|Lu, Dai; Wei, Han-Xun; Zhang, Jing et al. (2016) Part 1: Notch-sparing Î³-secretase inhibitors: The identification of novel naphthyl and benzofuranyl amide analogs. Bioorg Med Chem Lett 26:2129-32|
|Selkoe, Dennis J; Hardy, John (2016) The amyloid hypothesis of Alzheimer's disease at 25Â years. EMBO Mol Med 8:595-608|
|D'Avanzo, Carla; Aronson, Jenna; Kim, Young Hye et al. (2015) Alzheimer's in 3D culture: challenges and perspectives. Bioessays 37:1139-48|
Showing the most recent 10 out of 125 publications