Graduate School of Humanities and Sciences, Ochanomizu University, Tokyo 112-8610, Japan.
J Biochem. 2013 Sep;154(3):281-9. doi: 10.1093/jb/mvt051. Epub 2013 Jun 12.
Lipid droplets (LDs) are independent organelles in adipocytes that are composed of a lipid ester core surrounded by a phospholipid monolayer. The fatty acid composition of the phospholipid monolayer should determine the metabolism and dynamics of LDs. In this study, we examined the fatty acid composition of phospholipid monolayer in LDs during the differentiation of 3T3-L1 adipocytes. The levels of saturated fatty acids (SFAs), such as 16:0 and 18:0, in phosphatidylcholine (PC) and phosphatidylethanolamine (PE) of LDs decreased during differentiation. In contrast, the levels of monounsaturated fatty acids (MUFAs) such as 16:1n-7 and 18:1n-9 in PC and PE of LDs and the level of polyunsaturated fatty acids (PUFAs) such as 20:3n-6, 20:4n-6 and 22:6n-3 in PE of LDs increased during differentiation. These results suggest that the phospholipid monolayer in mature LDs is more fluid than that in nascent LDs. The fatty acid compositions of the LD monolayer were different from those of the microsome bilayer in the early stage of differentiation, but similar to those of the microsome bilayer in the late stage of differentiation. These data provide evidence that biophysical properties of the phospholipid monolayer in LDs change during adipocyte differentiation.
脂滴 (LDs) 是脂肪细胞中独立的细胞器，由脂质酯核心组成，周围环绕着一层磷脂单层。磷脂单层的脂肪酸组成应该决定 LD 的代谢和动态。在这项研究中，我们研究了 3T3-L1 脂肪细胞分化过程中 LD 中磷脂单层的脂肪酸组成。在分化过程中，LD 中的磷脂酰胆碱 (PC) 和磷脂酰乙醇胺 (PE) 中的饱和脂肪酸 (SFAs)，如 16:0 和 18:0 的水平降低。相比之下，LD 中的 PC 和 PE 中的单不饱和脂肪酸 (MUFAs)，如 16:1n-7 和 18:1n-9，以及 LD 中的 PE 中的多不饱和脂肪酸 (PUFAs)，如 20:3n-6、20:4n-6 和 22:6n-3 的水平在分化过程中增加。这些结果表明，成熟 LD 中的磷脂单层比初生 LD 中的磷脂单层更具流动性。LD 单层的脂肪酸组成在分化的早期与微粒体双层的脂肪酸组成不同，但与分化后期的微粒体双层的脂肪酸组成相似。这些数据提供了证据表明，脂肪细胞分化过程中 LD 中磷脂单层的物理性质发生变化。
