Reduction in ABCG1 in Type 2 diabetic mice increases macrophage foam cell formation.
Atherosclerosis development is accelerated severalfold in patients with Type 2 diabetes. In the initial stages of disease, monocytes transmigrate into the subendothelial space and differentiate into foam cells. Scavenger receptors and ATP binding cassette (ABC) Transporters play an important role in foam cell formation as they regulate the influx and efflux of oxidized lipids. Here, we show that peritoneal macrophages isolated from Type 2 diabetic db/db mice have decreased expression of the ABC transporter ABCG1 and increased expression of the scavenger receptor CD36. We found a 2-fold increase in accumulation of esterified cholesterol in diabetic db/db macrophages compared with wild-type control macrophages. Diabetic db/db macrophages also had impaired cholesterol efflux to high density lipoprotein but not to lipid-free apo A-I, suggesting that the increased esterified cholesterol in diabetic db/db macrophages was due to a selective loss of ABCG1-mediated efflux to high density lipoprotein. Additionally, we were able to confirm down-regulation of ABCG1 using C57BL/6J peritoneal macrophages cultured in elevated glucose in vitro (25 mM glucose for 7 days), suggesting that ABCG1 expression in diabetic macrophages is regulated by chronic exposure to elevated glucose. Diabetic KK(ay) mice were also studied and were found to have decreased ABCG1 expression without an increase in CD36. These observations demonstrate that ABCG1 plays a major role in macrophage cholesterol efflux and that decreased ABCG1 function can facilitate foam cell formation in Type 2 diabetic mice.
Mauldin
Jeremy P
JP
Department of Pharmacology, University of Virginia, Charlottesville, Virginia 22908; Cardiovascular Research Center, University of Virginia, Charlottesville, Virginia 22908.
Srinivasan
Suseela
S
Division of Endocrinology & Metabolism, University of Virginia, Charlottesville, Virginia 22908; Cardiovascular Research Center, University of Virginia, Charlottesville, Virginia 22908.
Mulya
Anny
A
Department of Pathology, Wake Forest University School of Medicine, Winston-Salem, North Carolina 27106.
Gebre
Abraham
A
Department of Pathology, Wake Forest University School of Medicine, Winston-Salem, North Carolina 27106.
Parks
John S
JS
Department of Pathology, Wake Forest University School of Medicine, Winston-Salem, North Carolina 27106.
Daugherty
Alan
A
Gill Heart Institute, Division of Cardiovascular Medicine, University of Kentucky, Lexington, Kentucky 40506.
Hedrick
Catherine C
CC
Department of Pharmacology, University of Virginia, Charlottesville, Virginia 22908; Division of Endocrinology & Metabolism, University of Virginia, Charlottesville, Virginia 22908; Cardiovascular Research Center, University of Virginia, Charlottesville, Virginia 22908. Electronic address: cch6n@virginia.edu.
D000070998:ATP Binding Cassette Transporter, Subfamily G, Member 1; D018528:ATP-Binding Cassette Transporters / Q000096:biosynthesis*; D000818:Animals; D018955:CD36 Antigens / Q000096:biosynthesis; D017931:DNA Primers / Q000737:chemistry; D003924:Diabetes Mellitus, Type 2 / Q000378:metabolism*; D004195:Disease Models, Animal; D005487:Foam Cells / Q000166:cytology* / Q000378:metabolism; D005947:Glucose / Q000378:metabolism; D008074:Lipoproteins / Q000096:biosynthesis*; D008264:Macrophages / Q000378:metabolism*; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D012323:RNA Processing, Post-Transcriptional; D034741:RNA, Small Interfering / Q000378:metabolism
C487540:ABCG1 protein, mouse; D000070998:ATP Binding Cassette Transporter, Subfamily G, Member 1; D018528:ATP-Binding Cassette Transporters; D018955:CD36 Antigens; D017931:DNA Primers; D008074:Lipoproteins; D034741:RNA, Small Interfering; D005947:Glucose