Heme oxygenase overexpression attenuates glucose-mediated oxidative stress in quiescent cell phase: linking heme to hyperglycemia complications.
Heme oxygenase (HO-1) is a stress protein, which has been suggested to participate in defense mechanisms against glucose induced oxidative injury. The purpose of this study was to examine the role of human HO-1 in attenuating glucose-mediated oxidative stress. We investigated the effect of high ambient glucose (15, 33 and 66 mM) on HO-1 gene expression in endothelial cells grown in a serum deprived media compared to the effect of glucose on exponentially grown cells (10% FBS). High glucose at 15 and 33 mM caused significant inhibition of HO-1 protein and activity in G0/G1 and in cells exponentially grown. Glucose concentration at 66 mM caused a significant increase in HO-1. Addition of heme (10 microM) increased HO-1 protein and bilirubin formation in G0/G1, in a time dependent manner peaking at 16 h. Glucose attenuated heme mediated increase in HO-1 proteins. RT-PCR demonstrated that glucose decreased the levels of HO-1 mRNA in both G0/G1 or cells grown in 10% FBS. The rate of HO-1 induction in response to heme was several fold higher in serum-starved cells compared to cells cultured in 10% FBS. Cells exposed to high glucose for up to 24 h had a significant increase in cellular heme and potentiated heme-mediated increase in generation of superoxide anion and 8-epi-isoprostane PGF(2alpha). HO-1 gene transduction prevented glucose-mediated elevation of 8-epi-isoprostane PGF(2alpha). These results imply that expression of HO-1 in G0/G1 cells may be a key player in decreasing cellular heme, associated with increased generation of bilirubin, and in attenuating glucose mediated oxidative stress.
Sacerdoti
David
D
University of Padova, Department of Clinical and Experimental Medicine, Italy.
Olszanecki
Rafal
R
Li Volti
Giovanni
G
Colombrita
Claudia
C
Scapagnini
Giovanni
G
Abraham
Nader G
NG
D002453:Cell Cycle / Q000502:physiology; D002478:Cells, Cultured; D003199:Computer Systems; D016895:Culture Media, Serum-Free; D015237:Dinoprost / Q000031:analogs & derivatives / Q000096:biosynthesis; D042783:Endothelial Cells / Q000166:cytology* / Q000378:metabolism*; D016193:G1 Phase; D005947:Glucose / Q000494:pharmacology*; D006418:Heme / Q000378:metabolism; D006419:Heme Oxygenase (Decyclizing) / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D006943:Hyperglycemia / Q000097:blood / Q000150:complications; D018384:Oxidative Stress / Q000187:drug effects* / Q000502:physiology; D012333:RNA, Messenger / Q000378:metabolism; D016192:Resting Phase, Cell Cycle; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013481:Superoxides / Q000378:metabolism
D016895:Culture Media, Serum-Free; D012333:RNA, Messenger; D013481:Superoxides; C075750:8-epi-prostaglandin F2alpha; D006418:Heme; D015237:Dinoprost; D006419:Heme Oxygenase (Decyclizing); D005947:Glucose