Extracellular vesicles modulate the Amyloid β aggregation via surface-expressed Prion Protein: a structural perspective of EV-Aβ interaction
Background
Extracellular vesicles (EVs) are excellent cargo vehicles for cell-to-cell communication and are involved in crucial brain functions, such as myelin maintenance and neurotransmission. EVs also play a modulatory role in amyloid aggregation in synucleinopathies and Alzheimer’s disease. We have previously demonstrated biochemically that Aβ42 aggregation is accelerated by EVs, particularly those expressing cellular prion protein (PrPC – a neuronally expressed Aβ42 receptor). However, the mechanistic and structural intricacies of this amyloid modulation are still not well understood. Here, we aim to better understand the structural perspective of EV-Aβ interaction, and the role of PrPC in EV-mediated Aβ fibrillation.
Methods
PrPC-expressing (WT) and -deficient (KO) EVs were derived from WT and PrPC-KO Neuro-2a cells and also from WT and PrPC-KO mice brains. The EVs were then incubated with recombinant Aβ42 in various settings. Data was obtained from small angle X-ray scattering (SAXS), super-resolution microscopy (SRM), Cryo-EM tomography, correlative proteomic profiling, and associative biochemical and biophysical methods.
Results
SAXS, EM, SRM, and aggregation assays highlighted potent Aβo-sequestering activity of the WT-EVs compared to the KO-EVs. Three dimensional reconstructions of EV-Aβ complexes using cryo-EM tomography highlight empirical involvement of PrPC in the EV-Aβ interaction. Correlative proteomic profiling of N2a-derived EVs pointed towards marked differences, however no variations were found for the Aβ binding proteins between WT- and KO-EVs.
Conclusion
Our data suggest crucial role of EVs expressing PrPC in Aβ aggregation, potentially acting as a rescue mechanism against Aβo toxicity in AD.
Keywords
Prion protein, Alzheimer’s disease, Amyloid β, protein aggregation, Cryo-EM tomography
Funding/Acknowledgments
MS and MG thank the Joachim Herz Stiftung, PIER Hamburg/Boston, PIER seed grants for support. AM-A is supported by the EU’s Horizon 2020 program via Marie Skłodowska-Curie grant. HCA acknowledges support from the CJD Foundation, USA, and the Alzheimer Forschung Initiative e.V., Germany.
Authors
Mohsin Shafiq1 (Corresponding Author: m.shafiq[at]uke[dot]de), Andreu Matamoros-Angles1, Ladan Amin2, E. Karadjuzovic1, Alexander Hartmann1, Behnam Mohammadi1, Stefano Da Vela3, Susanne C. Meister1, I. Egger1, A. Zafar1, C. Seuring4, Bente Siebels5, Hannah Voß5, Hartmut Schlüter5, Isidre Ferrer6, Hermann C. Altmeppen1, David A. Harris2, D. Svergun3, M. Glatzel1 (Corresponding Author: m.glatzel[at]uke[dot]de)