Perilipin family members preferentially sequester to either triacylglycerol- or cholesteryl ester-specific intracellular lipid storage droplets

Abstract

Perilipin family proteins (Plins) coat the surface of intracellular neutral lipid storage droplets in various cell types. Studies across diverse species demonstrate that Plins regulate lipid storage metabolism through recruitment of lipases and other regulatory proteins to lipid droplet surfaces. Mammalian genomes encode 5 distinct Plin gene members and additional protein forms derive from specific mRNA splice variants. However, it is not known if the different Plins have distinct functional properties. Using biochemical, cellular imaging, and flow cytometric analyses, we now show that within individual cells of various types, the different Plin proteins preferentially sequester to separate pools of lipid storage droplets. By examining ectopically expressed GFP fusions and all endogenous Plin protein forms, we demonstrate that different Plins sequester to lipid droplets, comprised distinctly of either triacylcerides or of cholesterol esters. Further, Plins with strong association preferences to TAG (or CE) droplets can re-direct the relative intracellular TAG/CE balance toward the targeted lipid. Our data suggest diversity of Plin function, alter previous assumptions about shared collective actions of the Plins, and indicate that each Plin can have separate and unique functions.