Molecular and Cellular Biochemistry

, Volume 232, Issue 1, pp 87–95

The expression of γ-glutamyltransferase in rat colon carcinoma cells is distinctly regulated during differentiation and oxidative stress

  • Idun Merete Mikkelsen
  • Bente Mortensen
  • Yannick Laperche
  • Nils-Erik Huseby
Article

DOI: 10.1023/A:1014809607758

Cite this article as:
Mikkelsen, I.M., Mortensen, B., Laperche, Y. et al. Mol Cell Biochem (2002) 232: 87. doi:10.1023/A:1014809607758

Abstract

Gamma glutamyltransferase (GGT) is a plasma membrane bound enzyme that initiates the degradation of glutathione. The presence of several promoters in the rat GGT gene indicates strict control and regulation of its expression. The aim of this study was to investigate whether the GGT gene was regulated differently after butyrate-induced differentiation and oxidative stress exposure of rat colon carcinoma cells and whether the regulation was related to the glutathione level. The activity of GGT was upregulated in a time-and-dose dependent manner after both butyrate and menadione incubations. The presence of antioxidants blocked the menadione but not the butyrate mediated induction of the enzyme. The level of intracellular glutathione was reduced after menadione, but not after butyrate incubations. Depletion of glutathione alone did not alter GGT activity. Reactive oxygen species (ROS) were not produced after incubations with butyrate, while menadione incubations produced ROS. The multiple GGT mRNA transcripts (mRNA I–V) that originate from the five distinct promoters were all present in the cell line. Incubations with butyrate enhanced mRNA II and IV transcripts whereas a reduction in mRNA IV-1 was noted during menadione incubations. The level of total GGT mRNA (I–V) was not altered when related to the amount of total β-actin mRNA. We conclude that GGT activity can be upregulated by at least two distinct mechanisms during differentiation and oxidative stress. Apparently, the regulation of the enzyme is not directly linked to the intracellular level of glutathione.

γ-glutamyltransferase sodium butyrate differentiation oxidative stress GGT mRNA isoforms rat colon carcinoma cells 

Copyright information

© Kluwer Academic Publishers 2002

Authors and Affiliations

  • Idun Merete Mikkelsen
  • Bente Mortensen
  • Yannick Laperche
  • Nils-Erik Huseby

There are no affiliations available

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