Interaction of glycated protein and DFO mimicked hypoxia in cellular responses of HUVECs.
The accelerated non-enzymatic modification of proteins by Maillard reaction during prolonged hyperglycemia is a key player in the diabetes associated pathology. In addition, hypoxia has been implicated in the recent past as a modulating factor. Therefore we have examined the interaction of glycation modified human serum albumin (AGE-HSA) and deferoxamine (DFO) mimicked hypoxia on the expression of hypoxia inducible factor 1α (HIF-1α), and the role of RAGE (receptor for AGE) signaling in up-regulation of HIF-1α. Expression of VEGF (a downstream target of HIF-1α) and sICAM-1 (inflammatory marker) was also detected. When HUVEC were subjected to hypoxia, highest expression of HIF-1α was observed. When treated with AGE-HSA at two concentrations, higher expression was found vis-a-vis control, with 0.2 mg ml(-1) than 2.0 mg ml(-1) which was mediated in part by RAGE as determined by RAGE silencing. However, when the cells were exposed to a combination treatment of hypoxia and AGE-HSA, a biphasic effect at the two different concentrations was observed as compared to the individual treatments. VEGF was synergistically up-regulated by hypoxia and AGE-HSA. On the other hand sICAM-1 was up-regulated by AGE-HSA but down-regulated by hypoxia. These results show that AGE-HSA functions as a non-hypoxic factor which modulates the expression of HIF-1α in a concentration dependent manner in the range studied. It can be concluded that glycated serum proteins may activate HIF-1α independently in diabetes. Further, when both glycated proteins and hypoxic conditions are present, they act in opposition in regulation of HIF-1α.
Centre for Biomedical Engineering, Indian Institute of Technology, Hauz Khas, New Delhi 110 016, India. nkarm@yahoo.com
Kanchan
K
Bala
Nivedita Karmakar
NK
Gohil
D003676:Deferoxamine / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D004338:Drug Combinations; D005260:Female; D015870:Gene Expression / Q000187:drug effects; D017127:Glycation End Products, Advanced / Q000494:pharmacology*; D061307:Human Umbilical Vein Endothelial Cells; D006801:Humans; D000860:Hypoxia / Q000378:metabolism; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000235:genetics / Q000378:metabolism; D007150:Immunohistochemistry; D018799:Intercellular Adhesion Molecule-1 / Q000235:genetics / Q000378:metabolism; D008954:Models, Biological; D010100:Oxygen / Q000494:pharmacology*; D034741:RNA, Small Interfering / Q000235:genetics; D000067759:Receptor for Advanced Glycation End Products; D011971:Receptors, Immunologic / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D012709:Serum Albumin / Q000494:pharmacology*; D000075462:Serum Albumin, Human; D015398:Signal Transduction / Q000187:drug effects; D042461:Vascular Endothelial Growth Factor A / Q000235:genetics / Q000378:metabolism
D004338:Drug Combinations; D017127:Glycation End Products, Advanced; C497442:HIF1A protein, human; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D034741:RNA, Small Interfering; D000067759:Receptor for Advanced Glycation End Products; D011971:Receptors, Immunologic; D012709:Serum Albumin; C467484:VEGFA protein, human; D042461:Vascular Endothelial Growth Factor A; C109748:advanced glycation end products-human serum albumin; D018799:Intercellular Adhesion Molecule-1; D003676:Deferoxamine; D010100:Oxygen; D000075462:Serum Albumin, Human