Structure Optimization of the Toxic Conformation Model of Amyloid β42 by Intramolecular Disulfide Bond Formation

• Published in: Chembiochem : a European journal of chemical biology 2022-04, Vol.23 (8), p.e202200029-n/a
• Main Authors: Matsushima, Yuka, Irie, Yumi, Kageyama, Yusuke, Bellier, Jean‐Pierre, Tooyama, Ikuo, Maki, Takahito, Kume, Toshiaki, Yanagita, Ryo C., Irie, Kazuhiro
• Format: Article
• Language: English
• Subjects: Alzheimer Disease - pathology; Alzheimer's disease; Amyloid - chemistry; Amyloid beta-Peptides - chemistry; Amyloid beta-Peptides - toxicity; amyloid-beta; Cell culture; Conformation; Cysteine; Cytotoxicity; disulfide bonds; Disulfides - chemistry; Electrophoresis; Gel electrophoresis; Homocysteine; Humans; Neurodegenerative diseases; Oligomers; Optimization; Peptide Fragments - chemistry; Peptide Fragments - toxicity; toxic conformations; Toxicity
• ISSN: 1439-4227; 1439-7633
• DOI: 10.1002/cbic.202200029

Amyloid β (Aβ) oligomers play a critical role in the pathology of Alzheimer's disease. Recently, we reported that a conformation‐restricted Aβ42 with an intramolecular disulfide bond through cysteine residues at positions 17/28 formed stable oligomers with potent cytotoxicity. To further optimize this compound as a toxic conformer model, we synthesized three analogues with a combination of cysteine and homocysteine at positions 17/28. The analogues with Cys‐Cys, Cys‐homoCys, or homoCys‐Cys, but not the homoCys‐homoCys analogue, exhibited potent cytotoxicity against SH‐SY5Y and THP‐1 cells even at 10 nM. In contrast, the cytotoxicity of conformation‐restricted analogues at positions 16/29 or 18/27 was significantly weaker than that of wild‐type Aβ42. Furthermore, thioflavin‐T assay, non‐denaturing gel electrophoresis, and morphological studies suggested that the majority of these conformation‐restricted analogues exists in an oligomeric state in cell culture medium, indicating that the toxic conformation of Aβ42, rather than the oligomeric state, is essential to induce cytotoxicity. The conformation‐restricted analogues of amyloid β42 (1–6) with an intramolecular disulfide bridge exist in an oligomeric state (250–800 kDa) in a cell culture medium. Nevertheless, only 1–3 with a Cys‐Cys or homoCys‐Cys bridge at positions 17/28 exhibit potent cytotoxicity against SH‐SY5Y and THP‐1 cells, suggesting that the formation of oligomers is not a necessary and sufficient condition to induce cytotoxicity.