Glutathione peroxidase protein expression and activity in human islets isolated for transplantation.
BACKGROUND
Overexpression of antioxidant enzymes has been reported to protect rodent beta cells from oxidative stress. However, very little is known about protein expression and activity of antioxidant enzymes in human islets.


RESULTS
Human islet protein levels by Western analysis and enzymatic activity for the key antioxidant enzymes superoxide dismutases (SODs), catalase, and glutathione peroxidase-1 (GPx) were examined. Enzyme protein expression and activity were in the order SODs > catalase > GPx. Human islet GPx protein expression was significantly less than that found for catalase (p < 0.0001) and levels of GPx activity were virtually undetectable. As glucose and estrogens have been proposed to alter antioxidant enzyme levels, we examined islet data from male and female donors separately and under varying glucose concentrations. We found significantly less (p < 0.001) GPx protein expression in islets from females compared to males, but no significant regulation by glucose in either gender.


CONCLUSIONS
Human islets have very low protein and activity levels for GPx, the essential enzyme for protection against excessive levels of intracellular lipid peroxides. GPx mimetics may be especially valuable in providing human islets with the broadest spectrum of protection against oxidative stress during isolation and transplantation.
Tonooka
Naoko
N
Pacific Northwest Research Institute, University of Washington, WA 98122, USA.
Oseid
Elizabeth
E
Zhou
Huarong
H
Harmon
Jamie S
JS
Robertson
R Paul
RP
D000328:Adult; D000818:Animals; D015415:Biomarkers / Q000378:metabolism; D015153:Blotting, Western; D002478:Cells, Cultured; D005260:Female; D005979:Glutathione Peroxidase / Q000096:biosynthesis*; D022781:Hepatocytes / Q000166:cytology / Q000201:enzymology; D006801:Humans; D007515:Islets of Langerhans / Q000166:cytology / Q000201:enzymology*; D016381:Islets of Langerhans Transplantation; D015227:Lipid Peroxidation / Q000502:physiology; D008297:Male; D008875:Middle Aged; D051381:Rats; D017208:Rats, Wistar; D013482:Superoxide Dismutase / Q000378:metabolism
D015415:Biomarkers; D005979:Glutathione Peroxidase; D013482:Superoxide Dismutase