Glycoxidized low-density lipoprotein regulates the expression of scavenger receptors in THP-1 macrophages.
Low-density lipoprotein (LDL) in patients with diabetes is subject to modification by both oxidation and glycation. In contrast to oxidized LDL, the biological effects of glycoxidized LDL have not been well characterised. In this study, the effects of oxidized, glycated, glycoxidized and oxidized LDL on scavenger receptor gene expressions, and the induction of oxidized LDL uptake and cholesteryl ester accumulation in THP-1 macrophages were compared. Modified LDL was incubated with THP-1 macrophages. Gene expression of scavenger receptor class A (SR-A), CD36 and scavenger receptor class B type I (SR-BI) was determined by quantitative reverse transcriptase PCR (RT-PCR). Glycoxidized LDL was able to significantly induce SR-A and CD36 expression by 3- and 4.5-fold, respectively, in macrophages whereas SR-BI expression was suppressed by glycoxidized LDL, glycated LDL and oxidized LDL. Incubation with glycoxidized LDL enhanced the uptake of DiI-labeled oxidized LDL by macrophages to a greater extent than that of glycated LDL or oxidized LDL. Glycoxidized LDL also induced a significant degree of intracellular cholesteryl ester accumulation. Taken together, our results would suggest that glycoxidized LDL might be an important candidate in the initiation of foam cell formation and might play a significant role in the pathogenesis of atherosclerosis in diabetes mellitus.
Lam
Michael C W
MC
Department of Medicine, Queen Mary Hospital, University of Hong Kong, Pokfulam Road, Hong Kong, China.
Tan
Kathryn C B
KC
Lam
Karen S L
KS
D018955:CD36 Antigens / Q000235:genetics; D002478:Cells, Cultured; D005786:Gene Expression Regulation; D017127:Glycation End Products, Advanced; D008077:Lipoproteins, LDL / Q000502:physiology*; D008264:Macrophages / Q000737:chemistry*; D011971:Receptors, Immunologic / Q000235:genetics*; D051116:Receptors, Scavenger; D020133:Reverse Transcriptase Polymerase Chain Reaction; D051117:Scavenger Receptors, Class A; D051122:Scavenger Receptors, Class B; D000093844:Glycated Proteins
D018955:CD36 Antigens; D017127:Glycation End Products, Advanced; D008077:Lipoproteins, LDL; D011971:Receptors, Immunologic; D051116:Receptors, Scavenger; D051117:Scavenger Receptors, Class A; D051122:Scavenger Receptors, Class B; C031797:glycated lipoproteins, LDL; D000093844:Glycated Proteins; C099252:oxidized low density lipoprotein