The lipid peroxidation products 4-oxo-2-nonenal and 4-hydroxy-2-nonenal promote the formation of α-synuclein oligomers with distinct biochemical, morphological, and functional properties.
Oxidative stress has been implicated in the etiology of neurodegenerative disorders with α-synuclein pathology. Lipid peroxidation products such as 4-oxo-2-nonenal (ONE) and 4-hydroxy-2-nonenal (HNE) can covalently modify and structurally alter proteins. Herein, we have characterized ONE- or HNE-induced α-synuclein oligomers. Our results demonstrate that both oligomers are rich in β-sheet structure and have a molecular weight of about 2000 kDa. Atomic force microscopy analysis revealed that ONE-induced α-synuclein oligomers were relatively amorphous, with a diameter of 40-80 nm and a height of 4-8 nm. In contrast, the HNE-induced α-synuclein oligomers had a protofibril-like morphology with a width of 100-200 nm and a height of 2-4 nm. Furthermore, neither oligomer type polymerized into amyloid-like fibrils despite prolonged incubation. Although more SDS and urea stable, because of a higher degree of cross-linking, ONE-induced α-synuclein oligomers were less compact and more sensitive to proteinase K treatment. Finally, both ONE- and HNE-induced α-synuclein oligomers were cytotoxic when added exogenously to a neuroblastoma cell line, but HNE-induced α-synuclein oligomers were taken up by the cells to a significantly higher degree. Despite nearly identical chemical structures, ONE and HNE induce the formation of off-pathway α-synuclein oligomers with distinct biochemical, morphological, and functional properties.
Department of Public Health and Caring Sciences, Uppsala University, Rudbeck Laboratory, 751 85 Uppsala, Sweden.
Thomas
T
Näsström
Therese
T
Fagerqvist
Mikael
M
Barbu
Mikael
M
Karlsson
Fredrik
F
Nikolajeff
Alex
A
Kasrayan
Monica
M
Ekberg
Lars
L
Lannfelt
Martin
M
Ingelsson
Joakim
J
Bergström
D000447:Aldehydes / Q000378:metabolism / Q000494:pharmacology*; D002470:Cell Survival / Q000187:drug effects; D006801:Humans; D002479:Inclusion Bodies / Q000378:metabolism / Q000648:ultrastructure; D015227:Lipid Peroxidation; D055503:Protein Multimerization; D055550:Protein Stability; D017433:Protein Structure, Secondary; D014407:Tumor Cells, Cultured; D051844:alpha-Synuclein / Q000378:metabolism* / Q000494:pharmacology
C403894:4-oxo-2-nonenal; D000447:Aldehydes; D051844:alpha-Synuclein; C027576:4-hydroxy-2-nonenal