Green Center for Systems Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA.
J Cell Biol. 2009 Nov 2;187(3):375-84. doi: 10.1083/jcb.200904140. Epub 2009 Oct 26.
Increases in key components of adipogenesis and lipolysis pathways correlate at the population-averaged level during adipogenesis. However, differentiating preadipocytes are highly heterogeneous in cellular and lipid droplet (LD) morphologies, and the degree to which individual cells follow population-averaged trends is unclear. In this study, we analyze the molecular heterogeneity of differentiating 3T3-L1 preadipocytes using immunofluorescence microscopy. Unexpectedly, we only observe a small percentage of cells with high simultaneous expression of markers for adipogenesis (peroxisome proliferator-activated receptor gamma [PPARgamma], CCAAT/enhancer-binding protein alpha, and adiponectin) and lipid accumulation (hormone-sensitive lipase, perilipin A, and LDs). Instead, we identify subpopulations of cells with negatively correlated expressions of these readouts. Acute perturbation of adipocyte differentiation with PPARgamma agonists, forskolin, and fatty acids induced subpopulation-specific effects, including redistribution of the percentage of cells in observed subpopulations and differential expression levels of PPARgamma. Collectively, our results suggested that heterogeneity observed during 3T3-L1 adipogenesis reflects a dynamic mixture of subpopulations with distinct physiological states.
在脂肪生成过程中，脂肪生成和脂解途径的关键成分的增加在人群平均水平上相关。然而，分化前脂肪细胞在细胞和脂滴（LD）形态上具有高度异质性，并且个体细胞遵循群体平均趋势的程度尚不清楚。在这项研究中，我们使用免疫荧光显微镜分析了分化的 3T3-L1 前脂肪细胞的分子异质性。出乎意料的是，我们只观察到一小部分细胞同时高度表达脂肪生成标志物（过氧化物酶体增殖物激活受体γ[PPARγ]、CCAAT/增强子结合蛋白α和脂联素）和脂质积累（激素敏感脂肪酶、脂滴包被蛋白 A 和 LD）。相反，我们确定了这些读数的负相关表达的细胞亚群。用 PPARγ激动剂、forskolin 和脂肪酸急性干扰脂肪细胞分化，诱导亚群特异性效应，包括观察到的亚群中细胞百分比的重新分布和 PPARγ的差异表达水平。总的来说，我们的结果表明，3T3-L1 脂肪生成过程中观察到的异质性反映了具有不同生理状态的亚群的动态混合物。
