Expression of gamma-glutamylcysteine synthetase in the liver of copper-deficient rats.
Copper deficiency in rats increases hepatic glutathione concentration. The present study was undertaken to determine the biochemical and molecular basis for the glutathione elevation. Weanling Sprague-Dawley rats were fed a purified diet deficient in copper (0.4 micrograms/g diet) or one containing adequate copper (5.7 micrograms/g diet) for 4 weeks. Hepatic glutathione concentration, the activity of the rate-limiting enzyme in glutathione biosynthesis, gamma-glutamylcysteine synthetase (gamma-GCS) and the relative amount of mRNA for the enzyme were determined. Hepatic glutathione concentration in copper-deficient rats was significantly elevated (6.6 vs 5.6 mumol/g). The activity of hepatic gamma-GCS was 1.6 times higher in the copper-deficient than in the copper-adequate rats (58.0 vs 35.9 nmol NADH/min.mg protein). The steady-state amount of mRNA for gamma-GCS was increased 5-fold in the copper-deficient rat liver. The findings demonstrate that the elevated hepatic glutathione concentration in copper-deficient rats results from upregulation of gamma-GCS activity. This study provides further understanding of changes in hepatic glutathione metabolism induced by copper deficiency.
Chen
Y
Y
Department of Pharmacology and Toxicology, University of North Dakota School of Medicine, Grand Forks 58202, USA.
Saari
J T
JT
Kang
Y J
YJ
D000704:Analysis of Variance; D000818:Animals; D015152:Blotting, Northern; D002570:Ceruloplasmin / Q000378:metabolism; D003300:Copper / Q000172:deficiency*; D015870:Gene Expression; D005721:Glutamate-Cysteine Ligase / Q000096:biosynthesis*; D005978:Glutathione / Q000378:metabolism; D006400:Hematocrit; D006454:Hemoglobins / Q000378:metabolism; D008099:Liver / Q000201:enzymology / Q000378:metabolism*; D008297:Male; D012333:RNA, Messenger / Q000032:analysis / Q000096:biosynthesis; D051381:Rats; D017207:Rats, Sprague-Dawley; D014131:Trace Elements / Q000378:metabolism
D006454:Hemoglobins; D012333:RNA, Messenger; D014131:Trace Elements; D003300:Copper; D002570:Ceruloplasmin; D005721:Glutamate-Cysteine Ligase; D005978:Glutathione