Regulation of mitochondrial cytochrome b mRNA by copper in cultured human hepatoma cells and rat liver.
Copper overload and deficiency are known to cause morphological and functional mitochondrial abnormalities. The reverse transcriptase-polymerase chain reaction (RT-PCR)-based method of differential display of mRNA was used to identify genes with altered expression in cultured human hepatoma cells (Hep G2) exposed to increasing concentrations of copper (0-100 microM, 24 h). Copper regulation of a cloned PCR product, identified as the gene for the mitochondrially encoded cytochrome b, was confirmed by Northern analysis and in situ hybridization. Copper toxicity increased cytochrome b mRNA abundance up to 3.6-fold, and copper chelation reduced it by 50%. Hepatic cytochrome b mRNA was also increased in rats fed a high-copper diet. Thapsigargin treatment resulted in a significant increase in cytochrome b mRNA, suggesting that an increase in intracellular calcium may be involved in the mechanism of copper action. Furthermore, although cyclohexamide (CHX) alone did not increase cytochrome b mRNA, the addition of CHX and copper resulted in a sixfold increase. These data suggest a role for cytochrome b in the response to increases or decreases in hepatic copper.
Levenson
C W
CW
Department of Nutrition, Food and Exercise Sciences, Florida State University, Tallahassee 32306-4340, USA.
Song
Y
Y
Narayanan
V S
VS
Fitch
C A
CA
Yeiser
E C
EC
D000818:Animals; D006528:Carcinoma, Hepatocellular / Q000188:drug therapy / Q000201:enzymology*; D002614:Chelating Agents / Q000494:pharmacology; D003300:Copper / Q000378:metabolism* / Q000494:pharmacology; D003513:Cycloheximide / Q000494:pharmacology; D003573:Cytochrome b Group / Q000235:genetics* / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D020869:Gene Expression Profiling; D005786:Gene Expression Regulation; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology; D008099:Liver / Q000187:drug effects / Q000378:metabolism; D008297:Male; D008930:Mitochondria, Liver / Q000187:drug effects / Q000201:enzymology*; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology; D012333:RNA, Messenger / Q000032:analysis*; D051381:Rats; D017207:Rats, Sprague-Dawley; D017422:Sequence Analysis, DNA; D019284:Thapsigargin / Q000494:pharmacology; D014407:Tumor Cells, Cultured; D015032:Zinc / Q000378:metabolism
D002614:Chelating Agents; D003573:Cytochrome b Group; D004791:Enzyme Inhibitors; D011500:Protein Synthesis Inhibitors; D012333:RNA, Messenger; D019284:Thapsigargin; D003300:Copper; D003513:Cycloheximide; D006861:Hydrogen Peroxide; D015032:Zinc