Lipid analysis reveals quiescent and regenerating liver-specific populations of lipid droplets.
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.
Department of Physiology, Faculty of Medicine and Dentistry, University of the Basque Country, B Sarriena sn, Leioa, 48940, Spain.
Itsaso
I
García-Arcos
Paola
P
González-Kother
Patricia
P
Aspichueta
Yuri
Y
Rueda
Begoña
B
Ochoa
Olatz
O
Fresnedo
D000818:Animals; D005260:Female; D006498:Hepatectomy; D050356:Lipid Metabolism; D008055:Lipids / Q000032:analysis / Q000737:chemistry; D008115:Liver Regeneration; D010713:Phosphatidylcholines / Q000378:metabolism; D010714:Phosphatidylethanolamines / Q000378:metabolism; D010743:Phospholipids / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D014280:Triglycerides / Q000378:metabolism
D008055:Lipids; D010713:Phosphatidylcholines; D010714:Phosphatidylethanolamines; D010743:Phospholipids; D014280:Triglycerides; C483858:phosphatidylethanolamine