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Adverse bioenergetic effects of N-acyl amino acids in human adipocytes overshadow beneficial mitochondrial uncoupling.
Redox Biol. 66:102874 (2023)
Objective: Enhancing energy turnover via uncoupled mitochondrial respiration in adipose tissue has great potential to improve human obesity and other metabolic complications. However, the amount of human brown adipose tissue and its uncoupling protein 1 (UCP1) is low in obese patients. Recently, a class of endogenous molecules, N-acyl amino acids (NAAs), was identified as mitochondrial uncouplers in murine adipocytes, presumably acting via the adenine nucleotide translocator (ANT). Given the translational potential, we investigated the bioenergetic effects of NAAs in human adipocytes, characterizing beneficial and adverse effects, dose ranges, amino acid derivatives and underlying mechanisms. Method: NAAs with neutral (phenylalanine, leucine, isoleucine) and polar (lysine) residues were synthetized and assessed in intact and permeabilized human adipocytes using plate-based respirometry. The Seahorse technology was applied to measure bioenergetic parameters, dose-dependency, interference with UCP1 and adenine nucleotide translocase (ANT) activity, as well as differences to the established chemical uncouplers niclosamide ethanolamine (NEN) and 2,4-dinitrophenol (DNP). Result: NAAs with neutral amino acid residues potently induce uncoupled respiration in human adipocytes in a dose-dependent manner, even in the presence of the UCP1-inhibitor guanosine diphosphate (GDP) and the ANT-inhibitor carboxyatractylate (CAT). However, neutral NAAs significantly reduce maximal oxidation rates, mitochondrial ATP-production, coupling efficiency and reduce adipocyte viability at concentrations above 25 μM. The in vitro therapeutic index (using induced proton leak and viability as determinants) of NAAs is lower than that of NEN and DNP. Conclusion: NAAs are potent mitochondrial uncouplers in human adipocytes, independent of UCP1 and ANT. However, previously unnoticed adverse effects harm adipocyte functionality, reduce the therapeutic index of NAAs in vitro and therefore question their suitability as anti-obesity agents without further chemical modifications.
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Publication type
Article: Journal article
Document type
Scientific Article
Keywords
Adipocytes ; Metabolism ; Mitochondria ; Obesity ; Ucp1 ; Uncoupling; Brown Adipose-tissue; Metabolism
ISSN (print) / ISBN
2213-2317
e-ISSN
2213-2317
Journal
Redox Biology
Quellenangaben
Volume: 66,
Article Number: 102874
Publisher
Elsevier
Publishing Place
Amsterdam [u.a.]
Non-patent literature
Publications
Reviewing status
Peer reviewed
Institute(s)
Institute of Medicinal Chemistry (IMC)
Grants
Novo Nordisk Research foundation
Ake Wiberg Stiftelse
Ake Wiberg Stiftelse