Regulation of mitochondrial cytochrome b mRNA by copper in cultured human hepatoma cells and rat liver

Biol Trace Elem Res. 1999 Nov;70(2):149-64. doi: 10.1007/BF02783856.

Abstract

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.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Carcinoma, Hepatocellular / drug therapy
  • Carcinoma, Hepatocellular / enzymology*
  • Chelating Agents / pharmacology
  • Copper / metabolism*
  • Copper / pharmacology
  • Cycloheximide / pharmacology
  • Cytochrome b Group / genetics*
  • Cytochrome b Group / metabolism
  • Enzyme Inhibitors / pharmacology
  • Gene Expression Profiling
  • Gene Expression Regulation
  • Humans
  • Hydrogen Peroxide / pharmacology
  • Liver / drug effects
  • Liver / metabolism
  • Male
  • Mitochondria, Liver / drug effects
  • Mitochondria, Liver / enzymology*
  • Protein Synthesis Inhibitors / pharmacology
  • RNA, Messenger / analysis*
  • Rats
  • Rats, Sprague-Dawley
  • Sequence Analysis, DNA
  • Thapsigargin / pharmacology
  • Tumor Cells, Cultured
  • Zinc / metabolism

Substances

  • Chelating Agents
  • Cytochrome b Group
  • Enzyme Inhibitors
  • Protein Synthesis Inhibitors
  • RNA, Messenger
  • Thapsigargin
  • Copper
  • Cycloheximide
  • Hydrogen Peroxide
  • Zinc