Department of Biomedical and Clinical Sciences, Cell Biology, Faculty of Medicine, Linköping University, SE-58185, Linköping, Sweden.
RG Adipocyte and Metabolism, Institute for Diabetes and Obesity, Helmholtz Center Munich, 85764, Neuherberg, Germany.
Eur J Pharmacol. 2023 Dec 5;960:176158. doi: 10.1016/j.ejphar.2023.176158. Epub 2023 Oct 26.
Obesity is a worldwide epidemic and natural products may hold promise in its treatment. The chlorophyll derivative 13--hydroxypheophytine (hpa) was isolated in a screen with zebrafish larvae to identify lipid reducing molecules from cyanobacteria. However, the mechanisms underlying the lipid-reducing effects of hpa in zebrafish larvae remain poorly understood. Thus, investigating the mechanism of action of hpa and validation in other model organisms such as mice represents important initial steps. In this study, we identified 14 protein targets of hpa in zebrafish larvae by thermal proteome profiling, and selected two targets (malate dehydrogenase and pyruvate kinase) involved in cellular metabolism for further validation by enzymatic measurements. Our findings revealed a dose-dependent inhibition of pyruvate kinase by hpa exposure using protein extracts of zebrafish larvae in vitro, and in exposure experiments from 3 to 5 days post fertilization in vivo. Analysis of untargeted metabolomics of zebrafish larvae detected 940 mass peaks (66 increased, 129 decreased) and revealed that hpa induced the formation of various phospholipid species (phosphoinositol, phosphoethanolamine, phosphatidic acid). Inter-species validation showed that brown adipocytes exposed to hpa significantly reduced the size of lipid droplets, increased maximal mitochondrial respiratory capacity, and the expression of PPARy during adipocyte differentiation. In line with our data, previous work described that reduced pyruvate kinase activity lowered hepatic lipid content via reduced pyruvate and citrate, and improved mitochondrial function via phospholipids. Thus, our data provide new insights into the molecular mechanism underlying the lipid reducing activities of hpa in zebrafish larvae, and species overlapping functions in reduction of lipids.
肥胖是一种全球性的流行病，天然产物可能在其治疗中具有潜力。叶绿素衍生物 13--羟基脱植基叶绿素（hpa）在斑马鱼幼虫中进行筛选，以鉴定来自蓝藻的降脂分子，从而被分离出来。然而，hpa 在斑马鱼幼虫中降低脂肪的作用机制仍知之甚少。因此，研究 hpa 的作用机制并在其他模式生物（如小鼠）中进行验证是重要的初始步骤。在这项研究中，我们通过热蛋白质组谱鉴定了斑马鱼幼虫中 hpa 的 14 个蛋白质靶标，并选择了两个涉及细胞代谢的靶标（苹果酸脱氢酶和丙酮酸激酶）进行进一步验证。我们的研究结果显示，在体外使用斑马鱼幼虫的蛋白质提取物进行实验时，hpa 暴露会导致丙酮酸激酶呈剂量依赖性抑制，而在体内受精后 3 至 5 天的暴露实验中也观察到了这种情况。对斑马鱼幼虫的非靶向代谢组学分析检测到 940 个质量峰（66 个增加，129 个减少），并表明 hpa 诱导了各种磷脂的形成（肌醇磷酸，磷酸乙醇胺，磷脂酸）。种间验证表明，暴露于 hpa 的棕色脂肪细胞显著减小了脂肪滴的大小，增加了最大线粒体呼吸能力，并在脂肪细胞分化过程中增加了 PPARγ 的表达。与我们的数据一致，先前的工作描述了降低的丙酮酸激酶活性通过减少丙酮酸和柠檬酸降低肝脂质含量，并通过磷脂改善线粒体功能。因此，我们的数据为 hpa 在斑马鱼幼虫中降低脂肪的活性的分子机制以及在降低脂肪方面的重叠功能提供了新的见解。
