Rinia Hilde A, Burger Koert N J, Bonn Mischa, Müller Michiel
Swammerdam Institute for Life Sciences, University of Amsterdam, 1098 SM Amsterdam, The Netherlands.
Biophys J. 2008 Nov 15;95(10):4908-14. doi: 10.1529/biophysj.108.137737. Epub 2008 Aug 8.
Lipid droplets (LDs) are highly dynamic organelles that perform multiple functions, including the regulated storage and release of cholesterol and fatty acids. Information on the molecular composition of individual LDs within their cellular context is crucial in understanding the diverse biological functions of LDs, as well as their involvement in the development of metabolic disorders such as obesity, type II diabetes, and atherosclerosis. Although ensembles of LDs isolated from cells and tissues were analyzed in great detail, quantitative information on the heterogeneity in lipid composition of individual droplets, and possible variations within single lipid droplets, is lacking. Therefore, we used a label-free quantitative method to image lipids within LDs in 3T3-L1 cells. The method combines submicron spatial resolution in three dimensions, using label-free coherent anti-Stokes Raman scattering microscopy, with quantitative analysis based on the maximum entropy method. Our method allows quantitative imaging of the chemistry (level of acyl unsaturation) and physical state (acyl chain order) of individual LDs. Our results reveal variations in lipid composition and physical state between LDs contained in the same cell, and even within a single LD.
脂滴（LDs）是高度动态的细胞器，具有多种功能，包括对胆固醇和脂肪酸的调控储存与释放。在细胞环境中，关于单个脂滴分子组成的信息对于理解脂滴的多种生物学功能以及它们在肥胖、II型糖尿病和动脉粥样硬化等代谢紊乱发展过程中的作用至关重要。尽管对从细胞和组织中分离出的脂滴集合进行了详细分析，但缺乏关于单个脂滴脂质组成异质性以及单个脂滴内可能变化的定量信息。因此，我们使用一种无标记定量方法对3T3-L1细胞中的脂滴内脂质进行成像。该方法将基于无标记相干反斯托克斯拉曼散射显微镜的三维亚微米空间分辨率与基于最大熵方法的定量分析相结合。我们的方法能够对单个脂滴的化学性质（酰基不饱和度水平）和物理状态（酰基链顺序）进行定量成像。我们的结果揭示了同一细胞内的脂滴之间，甚至单个脂滴内部脂质组成和物理状态的差异。
