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Schilling S, August A, Meleux M, Conradt C, Tremmel LM, Teigler S, Adam V, Müller UC, Koo EH, Kins S, Eggert S. APP family member dimeric complexes are formed predominantly in synaptic compartments. Cell Biosci 2023; 13:141. [PMID: 37533067 PMCID: PMC10398996 DOI: 10.1186/s13578-023-01092-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2023] [Accepted: 07/21/2023] [Indexed: 08/04/2023] Open
Abstract
BACKGROUND The amyloid precursor protein (APP), a key player in Alzheimer's disease (AD), is part of a larger gene family, including the APP like proteins APLP1 and APLP2. They share similar structures, form homo- and heterotypic dimers and exhibit overlapping functions. RESULTS We investigated complex formation of the APP family members via two inducible dimerization systems, the FKBP-rapamycin based dimerization as well as cysteine induced dimerization, combined with co-immunoprecipitations and Blue Native (BN) gel analyses. Within the APP family, APLP1 shows the highest degree of dimerization and high molecular weight (HMW) complex formation. Interestingly, only about 20% of APP is dimerized in cultured cells whereas up to 50% of APP is dimerized in mouse brains, independent of age and splice forms. Furthermore, we could show that dimerized APP originates mostly from neurons and is enriched in synaptosomes. Finally, BN gel analysis of human cortex samples shows a significant decrease of APP dimers in AD patients compared to controls. CONCLUSIONS Together, we suggest that loss of full-length APP dimers might correlate with loss of synapses in the process of AD.
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Affiliation(s)
- Sandra Schilling
- Department of Human Biology and Human Genetics, University of Kaiserslautern, 67663, Kaiserslautern, Germany
| | - Alexander August
- Department of Human Biology and Human Genetics, University of Kaiserslautern, 67663, Kaiserslautern, Germany
| | - Mathieu Meleux
- Department of Human Biology and Human Genetics, University of Kaiserslautern, 67663, Kaiserslautern, Germany
| | - Carolin Conradt
- Department of Human Biology and Human Genetics, University of Kaiserslautern, 67663, Kaiserslautern, Germany
| | - Luisa M Tremmel
- Department of Human Biology and Human Genetics, University of Kaiserslautern, 67663, Kaiserslautern, Germany
- Medical, Biochemistry & Molecular Biology, Center for Molecular Signaling (PZMS), Saarland University, 66421, Homburg, Germany
| | - Sandra Teigler
- Department of Human Biology and Human Genetics, University of Kaiserslautern, 67663, Kaiserslautern, Germany
| | - Virginie Adam
- Department of Human Biology and Human Genetics, University of Kaiserslautern, 67663, Kaiserslautern, Germany
| | - Ulrike C Müller
- Institute for Pharmacy and Molecular Biotechnology, University of Heidelberg, 69120, Heidelberg, Germany
| | - Edward H Koo
- Department of Neuroscience, University of California, San Diego (UCSD), La Jolla, CA, 92093-0662, USA
| | - Stefan Kins
- Department of Human Biology and Human Genetics, University of Kaiserslautern, 67663, Kaiserslautern, Germany
| | - Simone Eggert
- Department of Human Biology and Human Genetics, University of Kaiserslautern, 67663, Kaiserslautern, Germany.
- Department of Neurogenetics, Max-Planck-Institute for Multidisciplinary Sciences, City-Campus, Hermann-Rein-Str. 3, 37075, Göttingen, Germany.
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