Gocze P M, Freeman D A
Department of Internal Medicine, University of Oklahoma Health Sciences Center, Oklahoma City.
Cytometry. 1994 Oct 1;17(2):151-8. doi: 10.1002/cyto.990170207.
Neutral lipids accumulate in cellular lipid droplets. These droplets vary remarkably in number and amount between cells. In the present studies, the variability in lipid content was quantified by comparing the coefficient of variation of fluorescence histograms of nile red lipid-stained cells to the variability of cell size or cell protein distributions. This measure of lipid droplet variability persisted through a wide range of cell lipid content and averaged 4.4-fold more variability than cell size and 2.6-fold more variability than cell protein content. While looking for possible explanations for this variability, it was determined that cell to cell variability could not be explained by multiple clonal populations of cells or the confluence of the cell monolayer. Analysis of lipid variability using a more droplet-specific fluorescent dye, bodipy, reduced variability by about 44%. Cell cycle analysis revealed that G2 + M cells contained more lipid than S-phase cells, which in turn contained more lipid than G0 + G1 cells, but that variability was equally large throughout the cell cycle. The cholesteryl ester hydrolase inhibitor, diethylumbelliferyl phosphate, inhibited hydrolysis of both cholesteryl esters and triglycerides. Lipid content of diethylumbelliferyl phosphate-treated cells increased while the variability in lipid staining decreased by an average of 72%. Thus, the excess lipid fluorescence variability compared to cell size or protein fluorescence could in part be explained by variability in cellular hydrolysis of triglyceride and cholesteryl ester. Excess lipid fluorescent variability could be reduced by an average of 44% when a more lipid droplet-specific stain was used instead of nile red.
中性脂质在细胞脂滴中积累。这些脂滴在细胞之间的数量和含量差异显著。在本研究中，通过比较尼罗红脂质染色细胞荧光直方图的变异系数与细胞大小或细胞蛋白质分布的变异系数，对脂质含量的变异性进行了量化。这种脂滴变异性的测量方法在广泛的细胞脂质含量范围内都成立，其变异性平均比细胞大小高4.4倍，比细胞蛋白质含量高2.6倍。在寻找这种变异性的可能解释时，发现细胞间变异性不能用细胞的多个克隆群体或细胞单层的汇合来解释。使用一种更具脂滴特异性的荧光染料硼二吡咯（bodipy）分析脂质变异性，可使变异性降低约44%。细胞周期分析显示，G2+M期细胞比S期细胞含有更多脂质，而S期细胞又比G0+G1期细胞含有更多脂质，但在整个细胞周期中变异性同样很大。胆固醇酯水解酶抑制剂磷酸二乙伞形酮抑制胆固醇酯和甘油三酯的水解。磷酸二乙伞形酮处理的细胞脂质含量增加，而脂质染色的变异性平均降低72%。因此，与细胞大小或蛋白质荧光相比，脂质荧光的过量变异性部分可以用甘油三酯和胆固醇酯细胞水解的变异性来解释。当使用更具脂滴特异性的染料代替尼罗红时，过量的脂质荧光变异性平均可降低44%。
