García-Arcos Itsaso, González-Kother Paola, Aspichueta Patricia, Rueda Yuri, Ochoa Begoña, Fresnedo Olatz
Department of Physiology, Faculty of Medicine and Dentistry, University of the Basque Country, B Sarriena sn, Leioa, 48940, Spain.
Lipids. 2010 Dec;45(12):1101-8. doi: 10.1007/s11745-010-3492-2. Epub 2010 Nov 10.
The mammalian liver, a key organ in lipid homeostasis, can accumulate increased amounts of lipids in certain physiological conditions including liver regeneration. Lipid droplets (LD), the lipid storage organelles in the cytoplasm, are composed of a core of neutral lipids (mainly triacylglycerols and cholesteryl esters) surrounded by a monolayer of phospholipids and cholesterol with associated proteins. It is recognized that LD lipid composition is cell- and environment-specific and enables LD to carry out specific functions, but few descriptive studies aiming to interpret such differences have been published. We characterized eight density fractions of LD isolated from quiescent (control) and regenerating liver after partial hepatectomy, and grouped populations according to their lipid composition. LD from quiescent liver resembled the cholesteryl ester storage LD found in steroidogenic tissues, whereas in the regenerating tissue they were similar to adipocyte LD. Specifically, there were large, light LD with increased triacylglycerol content, the hallmark of liver regeneration. The apparent volume of the dense LD was, however, lower than in the quiescent density-matched populations, concomitant with increased phosphatidylcholine and phosphatidylethanolamine and decreased neutral lipid content. Analysis of the lipid profile of LD populations from quiescent and regenerating tissue leads us to define four physiological LD phenotypes for rat liver.
哺乳动物的肝脏是脂质稳态的关键器官，在包括肝脏再生在内的某些生理条件下会积累更多的脂质。脂滴（LD）是细胞质中的脂质储存细胞器，由中性脂质（主要是三酰甘油和胆固醇酯）核心组成，周围是一层磷脂和胆固醇以及相关蛋白质。人们认识到脂滴的脂质组成具有细胞和环境特异性，使脂滴能够执行特定功能，但很少有旨在解释这些差异的描述性研究发表。我们对部分肝切除术后从静止（对照）肝脏和再生肝脏中分离出的八个脂滴密度级分进行了表征，并根据它们的脂质组成对群体进行了分组。静止肝脏中的脂滴类似于在类固醇生成组织中发现的胆固醇酯储存脂滴，而在再生组织中，它们类似于脂肪细胞脂滴。具体而言，存在大量、较轻且三酰甘油含量增加的脂滴，这是肝脏再生的标志。然而，致密脂滴的表观体积低于静止状态下密度匹配的群体，同时磷脂酰胆碱和磷脂酰乙醇胺增加，中性脂质含量降低。对静止和再生组织中脂滴群体的脂质谱分析使我们能够定义大鼠肝脏的四种生理脂滴表型。
