Nuciferine’s dual pathway regulation of lipid metabolism: A biomechanical perspective based on HepG2 cells and <i>Caenorhabditis</i> <i>elegans</i>

The lipid-lowering properties of lotus leaf are primarily attributed to the active alkaloid, nuciferine. In this study, the role and underlying mechanisms of nuciferine in lipid metabolism regulation from a biomechanical perspective were investigated using molecular docking and in vitro and in vivo studies, employing HepG2 cells and Caenorhabditis elegans (C. elegans) as experimental models. The results indicated that nuciferine exhibited significant binding affinity to the targets Sterol Regulatory Element-Binding Protein-1c (SREBP-1c) and Peroxisome Proliferator-Activated Receptor alpha (PPARα), suggesting that it may modulate lipid metabolism via the SREBP-1c/PPARα pathway. In vitro experiments demonstrated that nuciferine significantly inhibited the oleic acid-induced accumulation of triglycerides (TG) and total cholesterol (TC) in HepG2 cells. Furthermore, atomic force microscopy (AFM) was employed to detect the changes in cell elasticity and adhesion force before and after nuciferine treatment. We hypothesized that the lipid-lowering effect of nuciferine might be related to the alterations in the mechanical properties of cells, which could further influence lipid metabolism pathways. Reverse transcription quantitative polymerase chain reaction (RT-qPCR) analysis revealed that nuciferine could regulate the expression of SREBP-1c and PPARα, as well as their downstream target genes, which further affects the biomechanical properties of cells. In vivo experiments showed that nuciferine effectively attenuated hepatic steatosis and reduced TG levels in C. elegans, while modulating the expression of Sterol regulatory element-binding protein-1 (sbp-1), Nuclear hormone receptor 49 (nhr-49), and their downstream target genes. These changes may affect lipid metabolism through intercellular mechanical signaling. Furthermore, using mutant strains defective in sbp-1, nhr-49, fatty acid and triglyceride synthase 5 (fat-5); fat mass and obesity associated-like 6 (fat-6), and fat-6; fat mass and obesity associated-like 7 (fat-7) genes, the study provided further evidence that nuciferine’s lipid-lowering effects are mediated through the sbp-1/nhr-49 pathway. This study is the first to employ molecular docking to identify SREBP-1c and PPARα as the lipid-lowering targets of nuciferine and to confirm through in vitro and in vivo experiments that its efficacy depends on the SREBP-1c/sbp-1 and PPARα/nhr-49 pathways, thereby offering a new perspective for the treatment of lipid metabolic disorders from a biomechanical perspective.