Buechler C, Ritter M, Duong C Q, Orso E, Kapinsky M, Schmitz G
Institute of Clinical Chemistry and Laboratory Medicine, University of Regensburg, Franz-Josef-Strauss-Allee 11, D-93053, Regensburg, Germany.
Biochim Biophys Acta. 2001 May 31;1532(1-2):97-104. doi: 10.1016/s1388-1981(01)00121-4.
Adipophilin, a marker of lipid accumulation initially described in adipocytes, was recently shown to be induced in macrophage foam cells. We found that even freshly isolated blood monocytes express adipophilin and that the amount of adipophilin protein is variable in monocytes from different healthy individuals. However, the physiological expression of adipophilin does not correlate with the levels of free fatty acids, cholesterylesters or free cholesterol. Enzymatically modified low-density lipoprotein (E-LDL) induces rapid foam cell formation in monocytes and upregulates adipophilin mRNA and protein within 2 h of incubation. This rapid induction of adipophilin is accompanied by a significant increase of free fatty acids in monocytes incubated with E-LDL. Adipophilin facilitates the uptake of free fatty acids, and here we demonstrate that free fatty acids increase is related to the early upregulation of adipophilin expression in blood monocytes. Fatty acids are ligands for peroxisome proliferator-activated receptor-gamma (PPARgamma), and the upregulation of adipophilin mRNA by PPARgamma agonists like 15d-PGJ(2) and ciglitazone indicates that PPARgamma may mediate the induction of adipophilin expression in human blood monocytes.
脂联素是一种最初在脂肪细胞中发现的脂质积累标志物，最近研究表明它在巨噬细胞泡沫细胞中也会被诱导表达。我们发现，即使是刚分离出的血液单核细胞也表达脂联素，而且来自不同健康个体的单核细胞中脂联素蛋白的含量存在差异。然而，脂联素的生理性表达与游离脂肪酸、胆固醇酯或游离胆固醇的水平并无关联。酶修饰的低密度脂蛋白（E-LDL）可在单核细胞中迅速诱导泡沫细胞形成，并在孵育2小时内上调脂联素的mRNA和蛋白表达。脂联素的这种快速诱导伴随着与E-LDL共同孵育的单核细胞中游离脂肪酸的显著增加。脂联素有助于游离脂肪酸的摄取，在此我们证明游离脂肪酸的增加与血液单核细胞中脂联素表达的早期上调有关。脂肪酸是过氧化物酶体增殖物激活受体γ（PPARγ）的配体，15d-PGJ2和吡格列酮等PPARγ激动剂对脂联素mRNA的上调表明，PPARγ可能介导人血液单核细胞中脂联素表达的诱导。
