Alfonso-García Alba, Pfisterer Simon G, Riezman Howard, Ikonen Elina, Potma Eric O
University of California, Irvine, Department of Biomedical Engineering, Irvine, California 92697, United States.
University of Helsinki, Finland and Minerva Foundation Institute for Medical Research, Department of Anatomy and Research Programs Unit, Faculty of Medicine, Helsinki 00290, Finland.
J Biomed Opt. 2016 Jun;21(6):61003. doi: 10.1117/1.JBO.21.6.061003.
We generated a highly deuterated cholesterol analog (D38-cholesterol) and demonstrated its use for selective vibrational imaging of cholesterol storage in mammalian cells. D38-cholesterol produces detectable signals in stimulated Raman scattering (SRS) imaging, is rapidly taken up by cells, and is efficiently metabolized by acyl-CoA cholesterol acyltransferase to form cholesteryl esters. Using hyperspectral SRS imaging of D38-cholesterol, we visualized cholesterol storage in lipid droplets. We found that some lipid droplets accumulated preferentially unesterified D38-cholesterol, whereas others stored D38-cholesteryl esters. In steroidogenic cells, D38-cholesteryl esters and triacylglycerols were partitioned into distinct sets of lipid droplets. Thus, hyperspectral SRS imaging of D38-cholesterol demonstrates a heterogeneous incorporation of neutral lipid species, i.e., free cholesterol, cholesteryl esters, and triacylglycerols, between individual lipid droplets in a cell.
我们生成了一种高度氘代的胆固醇类似物（D38-胆固醇），并证明了其在哺乳动物细胞中用于胆固醇储存的选择性振动成像的用途。D38-胆固醇在受激拉曼散射（SRS）成像中产生可检测信号，能迅速被细胞摄取，并被酰基辅酶A胆固醇酰基转移酶有效代谢形成胆固醇酯。利用D38-胆固醇的高光谱SRS成像，我们观察到脂质滴中的胆固醇储存情况。我们发现，一些脂质滴优先积累未酯化的D38-胆固醇，而其他脂质滴则储存D38-胆固醇酯。在类固醇生成细胞中，D38-胆固醇酯和三酰甘油被分隔到不同的脂质滴组中。因此，D38-胆固醇的高光谱SRS成像显示了细胞内单个脂质滴之间中性脂质种类（即游离胆固醇、胆固醇酯和三酰甘油）的异质掺入情况。
