title: Inhibition of the mitochondrial enzyme ABAD restores the amyloid-β-mediated deregulation of estradiol.
abstract: Alzheimer's disease (AD) is a conformational disease that is characterized by amyloid-β (Aβ) deposition in the brain. Aβ exerts its toxicity in part by receptor-mediated interactions that cause down-stream protein misfolding and aggregation, as well as mitochondrial dysfunction. Recent reports indicate that Aβ may also interact directly with intracellular proteins such as the mitochondrial enzyme ABAD (Aβ binding alcohol dehydrogenase) in executing its toxic effects. Mitochondrial dysfunction occurs early in AD, and Aβ's toxicity is in part mediated by inhibition of ABAD as shown previously with an ABAD decoy peptide. Here, we employed AG18051, a novel small ABAD-specific compound inhibitor, to investigate the role of ABAD in Aβ toxicity. Using SH-SY5Y neuroblastoma cells, we found that AG18051 partially blocked the Aβ-ABAD interaction in a pull-down assay while it also prevented the Aβ42-induced down-regulation of ABAD activity, as measured by levels of estradiol, a known hormone and product of ABAD activity. Furthermore, AG18051 is protective against Aβ42 toxicity, as measured by LDH release and MTT absorbance. Specifically, AG18051 reduced Aβ42-induced impairment of mitochondrial respiration and oxidative stress as shown by reduced ROS (reactive oxygen species) levels. Guided by our previous finding of shared aspects of the toxicity of Aβ and human amylin (HA), with the latter forming aggregates in Type 2 diabetes mellitus (T2DM) pancreas, we determined whether AG18051 would also confer protection from HA toxicity. We found that the inhibitor conferred only partial protection from HA toxicity indicating distinct pathomechanisms of the two amyloidogenic agents. Taken together, our results present the inhibition of ABAD by compounds such as AG18051 as a promising therapeutic strategy for the prevention and treatment of AD, and suggest levels of estradiol as a suitable read-out.
authors.affiliation: Alzheimer's & Parkinson's Disease Laboratory, Brain & Mind Research Institute, University of Sydney, Camperdown, New South Wales, Australia.
authors.forename: Yun-An
authors.initials: YA
authors.lastname: Lim
authors.forename: Amandine
authors.initials: A
authors.lastname: Grimm
authors.forename: Maria
authors.initials: M
authors.lastname: Giese
authors.forename: Ayikoe Guy
authors.initials: AG
authors.lastname: Mensah-Nyagan
authors.forename: J Ernest
authors.initials: JE
authors.lastname: Villafranca
authors.forename: Lars M
authors.initials: LM
authors.lastname: Ittner
authors.forename: Anne
authors.initials: A
authors.lastname: Eckert
authors.forename: Jürgen
authors.initials: J
authors.lastname: Götz
mesh_terms: D015094:3-Hydroxyacyl CoA Dehydrogenases / Q000378:metabolism*; D016229:Amyloid beta-Peptides / Q000378:metabolism / Q000633:toxicity*; D002460:Cell Line; D019069:Cell Respiration / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D019610:Cytoprotection / Q000187:drug effects; D015536:Down-Regulation / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000737:chemistry / Q000494:pharmacology; D004958:Estradiol / Q000378:metabolism*; D006801:Humans; D058228:Islet Amyloid Polypeptide / Q000378:metabolism / Q000633:toxicity; D008928:Mitochondria / Q000187:drug effects* / Q000201:enzymology*; D010085:Oxidative Phosphorylation / Q000187:drug effects; D010101:Oxygen Consumption / Q000187:drug effects; D010446:Peptide Fragments / Q000378:metabolism / Q000633:toxicity*; D011485:Protein Binding / Q000187:drug effects; D017382:Reactive Oxygen Species / Q000378:metabolism
chemical_list: D016229:Amyloid beta-Peptides; D004791:Enzyme Inhibitors; D058228:Islet Amyloid Polypeptide; D010446:Peptide Fragments; D017382:Reactive Oxygen Species; C075222:amyloid beta-protein (1-42); D004958:Estradiol; D015094:3-Hydroxyacyl CoA Dehydrogenases; C108634:HSD17B10 protein, human