alpha-Tocopherol transfer protein expression in rat liver exposed to hyperoxia.
alpha-Tochopherol transfer protein (alpha TTP), a 32 kDa protein exclusively expressed in liver cytosol, has a high binding affinity for alpha-tochopherol. The factors that regulate the expression of hepatic alpha TTP are not clearly understood. In this study, we investigated whether or not exposure to hyperoxia (> 95% O2 for 48 h) could alter the expression of hepatic alpha TTP. We also examined the association between the expression of antioxidant enzymes (hepatic glutathione peroxidase (GPX) and Mn-superoxide dismutase (Mn-SOD)) and the expression of hepatic alpha TTP. The levels of thiobarbituric acid-reactive substances (TBARS) in both plasma and liver were significantly higher after rats were exposed to hyperoxia for 48 h when compared with the levels in control rats. Northern blotting showed a decrease in the expression of alpha TTP messenger RNA (mRNA) after hyperoxia, although the alpha TTP protein level remained constant. Expression of Mn-SOD mRNA and protein, as well as the expression of GPX mRNA, were stable after hyperoxia. These findings indicate that mRNA for hepatic alpha TTP, rather than Mn-SOD or GPX, may be highly responsive to oxidative stress.
Ban
Ryoichi
R
Department of Pediatrics, Osaka Medical College, Daigaku-machi 2-7, Takatsuki, Osaka 569-8686, Japan.
Takitani
Kimitaka
K
Kim
Han-Suk
HS
Murata
Takuji
T
Morinobu
Takao
T
Ogihara
Tohru
T
Tamai
Hiroshi
H
D000410:Alanine Transaminase / Q000378:metabolism; D000818:Animals; D015152:Blotting, Northern; D015153:Blotting, Western; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism*; D005979:Glutathione Peroxidase / Q000378:metabolism; D018496:Hyperoxia / Q000378:metabolism*; D015227:Lipid Peroxidation; D008099:Liver / Q000166:cytology / Q000378:metabolism*; D008110:Liver Extracts; D008297:Male; D018384:Oxidative Stress / Q000502:physiology; D012333:RNA, Messenger / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D013482:Superoxide Dismutase / Q000378:metabolism; D024502:alpha-Tocopherol / Q000378:metabolism*
D002352:Carrier Proteins; D008110:Liver Extracts; D012333:RNA, Messenger; C017763:alpha-tocopherol transfer protein; D005979:Glutathione Peroxidase; D013482:Superoxide Dismutase; D000410:Alanine Transaminase; D024502:alpha-Tocopherol