title: Adipose tissue depot-specific differences in adipocyte apolipoprotein E expression.
abstract: Important differences in gene expression have been documented in adipocytes derived from specific adipose tissue depots. We have previously documented an important role for adipocyte apolipoprotein E (apoE) in modulating adipocyte and adipose tissue triglyceride and lipoprotein metabolism. We now evaluate the endogenous expression of apoE in adipocytes isolated from unique adipose tissue depots in 4 different species. Adipocyte apoE expression is higher in subcutaneous fat compared with visceral fat in humans, mice, rats, and baboons. In baboons, evaluation of apoE expression in 5 adipose tissue depots (subcutaneous abdominal, subcutaneous gluteal, visceral, pericardial, epicardial) showed that, compared with subcutaneous abdominal adipocytes, the level of apoE expression is similar in subcutaneous gluteal, lower in visceral and pericardial, and higher in epicardial adipocytes. Consistent with previously demonstrated suppression of adipocyte apoE by adipose tissue inflammation, adipose tissue depots with lower apoE expression demonstrated greater infiltration of macrophages and an increased expression of tumor necrosis factor-α messenger RNA. Depot-specific differences in apoE expression were maintained after in vitro differentiation. Adipocytes isolated from depots with lower apoE expression manifested lower rates of triglyceride synthesis in the absence and presence of triglyceride-rich lipoproteins. Adenoviral-mediated increase of apoE expression in omental adipocytes increased triglyceride synthesis in these cells. Our results demonstrate significant heterogeneity in adipocyte apoE expression across adipose tissue depots in several species. Because of its role in modulating adipocyte triglyceride and lipoprotein metabolism, depot-specific differences in endogenous adipocyte apoE could have important implications for modulating the accumulation of lipid in these depots.
authors.affiliation: Department of Medicine, University of Illinois at Chicago, Chicago, IL, USA.
authors.forename: Zhi H
authors.initials: ZH
authors.lastname: Huang
authors.forename: Doris J
authors.initials: DJ
authors.lastname: Espiritu
authors.forename: Arlene
authors.initials: A
authors.lastname: Uy
authors.forename: Ai-Xuan
authors.initials: AX
authors.lastname: Holterman
authors.forename: Joseph
authors.initials: J
authors.lastname: Vitello
authors.forename: Theodore
authors.initials: T
authors.lastname: Mazzone
mesh_terms: D017667:Adipocytes / Q000378:metabolism*; D000818:Animals; D001057:Apolipoproteins E / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism*; D015153:Blotting, Western; D004041:Dietary Fats / Q000008:administration & dosage; D005260:Female; D005786:Gene Expression Regulation; D006801:Humans; D050152:Intra-Abdominal Fat / Q000378:metabolism*; D008074:Lipoproteins / Q000378:metabolism; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D009765:Obesity / Q000378:metabolism*; D010215:Papio; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D020133:Reverse Transcriptase Polymerase Chain Reaction; D050151:Subcutaneous Fat / Q000378:metabolism*; D014280:Triglycerides / Q000378:metabolism
chemical_list: D001057:Apolipoproteins E; D004041:Dietary Fats; D008074:Lipoproteins; D012333:RNA, Messenger; D014280:Triglycerides