Heme oxygenase-1 is an important modulator in limiting glucose-induced apoptosis in human umbilical vein endothelial cells.
Hyperglycaemia is associated with oxidative stress. The inducible isoform of heme oxygenase (HO-1) is an effective system to counteract oxidative stress, yet it is unclear how hyperglycaemia affects HO-1. In this study, we explored: 1) the HO-1 protein content and HO activity in human umbilical vein endothelial cells (HUVECs) exposed to different glucose concentrations, and 2) the mechanisms which account for the high glucose-induced effects on HO-1. We evaluated HO-1 protein expression, HO activity, apoptosis and reactive oxygen species (ROS) in HUVECs treated for 48 h with 5.5, 10 and 20 mM glucose. A dose-dependent production of reactive oxygen species was observed. At 10 mM glucose, an increase of HO-1 protein expression and HO activity was observed, whereas at 20 mM, there was no change in protein content and activity relative to at 5.5 mM glucose. HO-1 protein expression in HUVECs exposed to 20 mM of glucose was increased in the presence of 20 U/ml superoxide dismutase (SOD). HO-1 gene silencing augments ROS production both at 5.5 and 10 mM glucose, leading to an increased apoptosis. We conclude that, in endothelial cells, the regulation of HO-1 by glucose is dependent upon levels of glucose itself. Lack of homeostatic HO-1 upregulation fails to protect from oxidative damage and results in a higher rate of apoptotic cell death.
Iori
Elisabetta
E
Department of Clinical and Experimental Medicine, University of Padua, School of Medicine, Via Giustiniani 2, 35128 Padova, Italy.
Pagnin
Elisa
E
Gallo
Alessandra
A
Calò
Lorenzo
L
Murphy
Ellen
E
Ostuni
Francesca
F
Fadini
Gian Paolo
GP
Avogaro
Angelo
A
D017209:Apoptosis / Q000187:drug effects*; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D004338:Drug Combinations; D004730:Endothelium, Vascular / Q000187:drug effects / Q000201:enzymology* / Q000473:pathology; D015971:Gene Expression Regulation, Enzymologic; D020868:Gene Silencing; D005947:Glucose / Q000494:pharmacology*; D051547:Heme Oxygenase-1 / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D012333:RNA, Messenger / Q000378:metabolism; D034741:RNA, Small Interfering / Q000008:administration & dosage / Q000235:genetics; D017382:Reactive Oxygen Species / Q000378:metabolism; D013482:Superoxide Dismutase / Q000494:pharmacology; D014162:Transfection; D014471:Umbilical Veins / Q000166:cytology
D004338:Drug Combinations; D012333:RNA, Messenger; D034741:RNA, Small Interfering; D017382:Reactive Oxygen Species; D051547:Heme Oxygenase-1; D013482:Superoxide Dismutase; D005947:Glucose