Hyperglycemia-induced reactive oxygen species increase expression of the receptor for advanced glycation end products (RAGE) and RAGE ligands.
OBJECTIVE
RAGE interacts with the endogenous ligands S100 calgranulins and high mobility group box 1 (HMGB1) to induce inflammation. Since hyperglycemia-induced reactive oxygen species (ROS) activate many pathways of diabetic tissue damage, the effect of these ROS on RAGE and RAGE ligand expression was evaluated.


METHODS
Expression of RAGE, S100A8, S100A12, and HMGB1 was evaluated in human aortic endothelial cells (HAECs) incubated in normal glucose, high glucose, and high glucose after overexpression of either uncoupling protein 1 (UCP1), superoxide dismutase 2 (SOD2), or glyoxalase 1 (GLO1). Expression was also evaluated in normal glucose after knockdown of GLO1. Expression was next evaluated in high glucose after knockdown of nuclear factor (NF)-kappaB p65 (RAGE) and after knockdown of activated protein-1 (AP-1) (S100A8, S100A12, and HMGB1), and chromatin immunoprecipitation (ChIP) was performed +/- GLO1 overexpression for NFkappaB p65 (RAGE promoter) and AP-1 (S100A8, S100A12, and HMGB1 promoters). Finally, endothelial cells from nondiabetic mice, STZ diabetic mice, and STZ diabetic mice treated with the superoxide dismutase mimetic Mn(III)tetrakis(4-benzoic acid)porphyrin chloride (MnTBAP) were evaluated.


RESULTS
High glucose increased RAGE, S100A8, S100A12, and HMGB1 expression, which was normalized by overexpression of UCP1, SOD2, or GLO1. GLO1 knockdown mimicked the effect of high glucose, and in high glucose, overexpression of GLO1 normalized increased binding of NFkappaB p65 and AP-1. Diabetes increased RAGE, S100A8, and HMGB1 expression, and MnTBAP treatment normalized this.


CONCLUSIONS
These results show that hyperglycemia-induced ROS production increases expression of RAGE and RAGE ligands. This effect is mediated by ROS-induced methylglyoxal, the major substrate of glyoxalase 1.
Yao
Dachun
D
Department of Medicine, Diabetes Research Center, Albert Einstein College of Medicine, Bronx, New York, USA.
Brownlee
Michael
M
D000818:Animals; D001011:Aorta / Q000502:physiology*; D017931:DNA Primers; D003921:Diabetes Mellitus, Experimental / Q000378:metabolism; D004730:Endothelium, Vascular / Q000502:physiology*; D005822:Genetic Vectors; D024243:HMGB1 Protein / Q000235:genetics; D006801:Humans; D006943:Hyperglycemia / Q000503:physiopathology*; D007791:Lactoylglutathione Lyase / Q000235:genetics; D008665:Metalloporphyrins / Q000494:pharmacology*; D051379:Mice; D020928:Mitogen-Activated Protein Kinases; D011401:Promoter Regions, Genetic; D012333:RNA, Messenger / Q000235:genetics; D017382:Reactive Oxygen Species / Q000378:metabolism*; D000067759:Receptor for Advanced Glycation End Products / Q000187:drug effects / Q000235:genetics*; D018808:Transcription Factor AP-1 / Q000235:genetics
D017931:DNA Primers; D024243:HMGB1 Protein; D008665:Metalloporphyrins; D012333:RNA, Messenger; D017382:Reactive Oxygen Species; D000067759:Receptor for Advanced Glycation End Products; D018808:Transcription Factor AP-1; C517163:manganese(III) tetrakis(5,10,15,20-benzoic acid)porphyrin; C498977:Mok protein, mouse; D020928:Mitogen-Activated Protein Kinases; D007791:Lactoylglutathione Lyase