Gopal Sowmya Shree, Eligar Sachin M, Vallikannan Baskaran, Ponesakki Ganesan
Department of Molecular Nutrition, CSIR-Central Food Technological Research Institute (CFTRI), Mysuru 570 020, India; Academy of Scientific and Innovative Research (AcSIR), Ghaziabad 201 002, India.
Academy of Scientific and Innovative Research (AcSIR), Ghaziabad 201 002, India; Department of Protein Chemistry and Technology, CSIR-Central Food Technological Research Institute (CFTRI), Mysuru 570 020, India.
Biochim Biophys Acta Mol Cell Biol Lipids. 2021 Jan;1866(1):158812. doi: 10.1016/j.bbalip.2020.158812. Epub 2020 Sep 11.
A comprehensive molecular mechanistic role of lutein on adipogenesis is not well understood. The present study focused to evaluate the effect of lutein at the early and late phase of adipocyte differentiation in vitro using a 3T3-L1 cell model. The effect of purified carotenoid on the viability of normal and differentiated 3T3-L1 cells was analyzed by WST-1 assay. Oil Red O and Nile red staining were employed to observe lipid droplets in mature adipocytes. The effect of lutein on gene and protein expression of major transcription factors and adipogenic markers was analyzed by RT-PCR and western blotting, respectively. The role of lutein on mitotic clonal expansion was analyzed by flow cytometry. The results showed a significant reduction (p < 0.05) in the accumulation of lipid droplets in lutein-treated (5 μM) cells. Inhibition in lipid accumulation was associated with down-regulated expression of CEBP-α and PPAR-γ at gene and protein levels. Subsequently, lutein repressed gene expression of FAS, FABP4, and SCD1 in mature adipocytes. Interestingly, it blocks the protein expression of CEBP-α and PPAR-γ in the initial stages of adipocyte differentiation. This early-stage inhibition of adipocyte differentiation is linked with repressed phosphorylation AKT and ERK. Further, upregulated cyclin D and down-regulated CDK4 and CDK2 in lutein treated adipocytes enumerate its role in delaying the cell cycle progression at the G0/G1 phase. Our results emphasize that adipogenesis inhibitory efficacy of lutein is potentiated by halting early phase regulators of adipocyte differentiation, which strengthens the competency of lutein besides its inevitable presence in the human body.
叶黄素在脂肪生成中的全面分子机制作用尚未完全明确。本研究聚焦于使用3T3-L1细胞模型评估叶黄素在体外脂肪细胞分化早期和晚期的作用。通过WST-1检测分析纯化类胡萝卜素对正常及分化的3T3-L1细胞活力的影响。采用油红O和尼罗红染色观察成熟脂肪细胞中的脂滴。分别通过RT-PCR和蛋白质印迹法分析叶黄素对主要转录因子和脂肪生成标志物的基因和蛋白表达的影响。通过流式细胞术分析叶黄素对有丝分裂克隆扩增的作用。结果显示，用叶黄素处理（5 μM）的细胞中脂滴积累显著减少（p < 0.05）。脂质积累的抑制与CEBP-α和PPAR-γ在基因和蛋白水平的表达下调有关。随后，叶黄素抑制成熟脂肪细胞中FAS、FABP4和SCD1的基因表达。有趣的是，它在脂肪细胞分化的初始阶段阻断CEBP-α和PPAR-γ的蛋白表达。脂肪细胞分化的这种早期抑制与AKT和ERK磷酸化的抑制有关。此外，叶黄素处理的脂肪细胞中细胞周期蛋白D上调，CDK4和CDK2下调，表明其在G0/G1期延迟细胞周期进程中的作用。我们的结果强调，叶黄素通过阻断脂肪细胞分化的早期调节因子来增强其脂肪生成抑制功效，这除了叶黄素在人体中不可避免的存在外，还增强了叶黄素的作用能力。
