Ng 2019 J Biol Chem
| Ng J, Kaur H, Collier T, Chang K, Brooks AES, Allison JR, Brimble MA, Hickey A, Birch NP (2019) Site-specific glycations of AΞ²1-42 affect fibril formation and are neurotoxic. J Biol Chem [Epub ahead of print]. |
Ng J, Kaur H, Collier T, Chang K, Brooks AES, Allison JR, Brimble MA, Hickey A, Birch NP (2019) J Biol Chem
Abstract: Amyloid Ξ²1-42 (AΞ²1-42) peptide is involved in Alzheimer's disease (AD) pathogenesis and is prone to glycation, an irreversible process resulting in proteins with accumulated advanced glycated end products (AGEs). Nε-(carboxyethyl)lysine (CEL) is a common AD-associated AGE, occurring at either Lys-16 or Lys-28 of AΞ²1-42. Methylglyoxal is commonly used for the unspecific glycation of AΞ²1-42, which results in a complex mixture of AGE-modified peptides and makes interpretation of a causative AGE at a specific amino acid residue difficult. Here, we addressed this challenge by chemically synthesizing defined CEL glycations on AΞ²1-42 at Lys-16 (AΞ²-CEL16), Lys-28 (AΞ²-CEL28), and both Lys-16 and -28 (AΞ²-CEL16&28). We demonstrate that the double CEL glycation at Lys-16/28 of AΞ²1-42 had the most profound impact on amyloid fibril formation. In silico predictions indicated that AΞ²-CEL16&28 had a substantially decreased free-energy change, contributing to fibril destabilization, and a decreased aggregation rate. Single CEL glycations at Lys-28 had the least impact on fibril formation, and Lys-16 CEL glycations delayed fibril formation. We also tested these peptides for neuronal toxicity and impact on mitochondrial function in a retinoic acid-differentiated SH-SY5Y human neuroblastoma cell line and found that only AΞ²-CEL16 and AΞ²-CEL28 are neurotoxic, possibly through a non-mitochondrial pathway, whereas AΞ²-CEL16&28 is not neurotoxic. Interestingly, AΞ²-CEL16&28 depolarized the mitochondrial membrane potential, and AΞ²-CEL16 increased mitochondrial respiration at complex II, possibly indicating mitophagy or an alternative metabolic route, respectively. In summary, our results provide insights relevant for potential therapeutic approaches against neurotoxic CEL glycated AΞ²1-42.
Published under license by The American Society for Biochemistry and Molecular Biology, Inc. β’ Keywords: Alzheimer disease, N-epsilon-(carboxyethyl)lysine (CEL), Advanced glycated end product (AGE), Amyloid-beta (AB), Fibril, Glycation, Mitochondria, Neurodegeneration, Protein aggregation β’ Bioblast editor: Plangger M β’ O2k-Network Lab: NZ Auckland Hickey AJ
Labels: MiParea: Respiration
Pathology: Alzheimer's
Organism: Human Tissue;cell: Neuroblastoma Preparation: Permeabilized cells
Coupling state: LEAK, OXPHOS, ET
Pathway: N, S, CIV, NS, ROX
HRR: Oxygraph-2k
Labels, 2019-04
