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 Aβ1-42 affect fibril formation and are neurotoxic. J Biol Chem 294:8806-18.

» PMID: 30996005 Open Access

Ng J, Kaur H, Collier T, Chang K, Brooks AES, Allison JR, Brimble MA, Hickey A, Birch NP (2019) J Biol Chem

Abstract: Amyloid β1-42 (Aβ1-42) 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 Aβ1-42. Methylglyoxal is commonly used for the unspecific glycation of Aβ1-42, 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 Aβ1-42 at Lys-16 (Aβ-CEL16), Lys-28 (Aβ-CEL28), and both Lys-16 and -28 (Aβ-CEL16&28). We demonstrate that the double CEL glycation at Lys-16/28 of Aβ1-42 had the most profound impact on amyloid fibril formation. In silico predictions indicated that Aβ-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 Aβ-CEL16 and Aβ-CEL28 are neurotoxic, possibly through a non-mitochondrial pathway, whereas Aβ-CEL16&28 is not neurotoxic. Interestingly, Aβ-CEL16&28 depolarized the mitochondrial membrane potential, and Aβ-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 Aβ1-42.

Published under license by The American Society for Biochemistry and Molecular Biology, Inc. • Keywords: Alzheimer disease, N-epsilon-(carboxyethyl)lysine (CEL), Advanced glycated end product (AGE), Amyloid-beta (AB), Fibril, Glycation, Mitochondria, Neurodegeneration, Protein aggregation • Bioblast editor: Plangger M • 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