ApoA-I induces a preferential efflux of monounsaturated phosphatidylcholine and medium chain sphingomyelin species from a cellular pool distinct from HDL₃ mediated phospholipid efflux

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• 作者：Rainer Schifferer ; Gerhard Liebisch ; Sascha B ; ulik ; Thomas Langmann ; Ashraf Dada ; Gerd Schmitz
• 关键词：Tandem mass spectrometry ; Stable isotope labeling ; Electrospray ionization ; Quantitative lipid analysis ; Lipidomics
• 刊名：Biochimica et Biophysica Acta (BBA)/Molecular and Cell Biology of Lipids
• 出版年：2007
• 出版时间：July 2007
• 年：2007
• 卷：1771
• 期：7
• 页码：853-863
• 全文大小：585 K

文摘

Electrospray ionization tandem mass spectrometry (ESI-MS/MS) was used for a detailed analysis of cellular phospholipid and cholesterol efflux in free cholesterol (FC) loaded human primary fibroblasts and human monocyte-derived macrophages (HMDM) loaded with enzymatically modified LDL (E-LDL). Although both cell models differed significantly in their cellular lipid composition, a higher apoA-I specific efflux was found for monounsaturated phosphatidylcholine (PC) species together with a decreased contribution of polyunsaturated PC species in both cell types. Moreover, medium chain sphingomyelin (SPM) species SPM 14:0 and SPM 16:1 were translocated preferentially to apoA-I in both cell types. In contrast to fibroblasts, HMDM displayed a considerable proportion of cholesteryl esters (CE) in basal and apoA-I specific efflux media, most likely due to secretion of CE associated to apoE. Analysis of HDL₃ mediated lipid efflux from HMDM using D₉-choline and ¹³C₃-FC stable isotope labeling revealed significantly different D₉-PC and D₉-SPM species pattern for apoA-I and HDL₃ specific efflux media, which indicates a contribution of distinct cellular phospholipid pools to apoA-I and HDL₃ mediated efflux. Together with a partial loading of fibroblasts and HMDM with HDL₃-derived CE species, these data add further evidence for retroendocytosis of HDL. In summary, analysis of apoA-I/ABCA1 and HDL₃ mediated lipid efflux by ESI-MS/MS demonstrated a preferential efflux of monounsaturated PC and medium chain SPM to apoA-I. Moreover, this is the first study, which provides evidence for distinct cellular phospholipid pools used for lipid transfer to apoA-I and HDL₃ from the analysis of phospholipid species pattern in HMDM.