Department of Molecular Biosciences, The Wenner-Gren Institute, The Arrhenius Laboratories F3, Stockholm University, SE-106 91, Stockholm, Sweden.
Institute of Medicinal Chemistry, Helmholtz Zentrum München, German Research Center for Environmental Health (GmbH), Neuherberg, Germany; Institute of Organic Chemistry, Leibniz Universität Hannover, Hannover, Germany.
Redox Biol. 2023 Oct;66:102874. doi: 10.1016/j.redox.2023.102874. Epub 2023 Sep 2.
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.
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).
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.
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.
通过解偶联线粒体呼吸来提高脂肪组织的能量转换，这对于改善人类肥胖和其他代谢并发症具有巨大潜力。然而，肥胖患者的棕色脂肪组织及其解偶联蛋白 1（UCP1）的含量较低。最近，一类内源性分子，N-酰基氨基酸（NAAs），被鉴定为鼠脂肪细胞中的线粒体解偶联剂，可能通过腺嘌呤核苷酸转运蛋白（ANT）起作用。鉴于其潜在的转化能力，我们研究了 NAA 对人类脂肪细胞的生物能学效应，分析了其有益和不利影响、剂量范围、氨基酸衍生物和潜在机制。
用平板呼吸仪检测完整和通透的人脂肪细胞中具有中性（苯丙氨酸、亮氨酸、异亮氨酸）和极性（赖氨酸）残基的 NAA 的生物能学参数、剂量依赖性、对 UCP1 和腺嘌呤核苷酸转运蛋白（ANT）活性的干扰，以及与已建立的化学解偶联剂尼可刹米乙醇胺（NEN）和 2,4-二硝基苯酚（DNP）的差异。
具有中性氨基酸残基的 NAA 以剂量依赖性方式在人脂肪细胞中强烈诱导解偶联呼吸，即使在 UCP1 抑制剂鸟苷二磷酸（GDP）和 ANT 抑制剂羧基三甲胺（CAT）存在的情况下也是如此。然而，中性 NAA 在浓度高于 25μM 时，显著降低最大氧化速率、线粒体 ATP 生成、偶联效率，并降低脂肪细胞活力。NAAs 的体外治疗指数（以诱导质子泄漏和活力为决定因素）低于 NEN 和 DNP。
NAAs 是人类脂肪细胞中强有力的线粒体解偶联剂，独立于 UCP1 和 ANT。然而，以前未被注意到的不良反应会损害脂肪细胞的功能，降低 NAAs 在体外的治疗指数，因此在没有进一步化学修饰的情况下，质疑它们作为抗肥胖剂的适用性。
