Referenced in: none

Automatically associated channels: Kv10.1

Title: Involvement of calcium ion in elevation of mRNA for gamma-glutamylcysteine synthetase (gamma-GCS) induced by low-dose gamma-rays.

Authors: K Teshima, A Yamamoto, K Yamaoka, Y Honda, S Honda, T Sasaki, S Kojima

Journal, date & volume: Int. J. Radiat. Biol., 2000 Dec , 76, 1631-9

PubMed link: http://www.ncbi.nlm.nih.gov/pubmed/11133045

Abstract
To investigate the mechanism of the intracellular glutathione elevation induced by low-dose gamma-radiation.RAW 264.7 cells were irradiated with 1-400cGy gamma-rays. Intracellular total glutathione content was determined by DTNB-recycling assay. Expression of mRNA for intracellular glutathione synthesis-related enzymes with or without treatment with various inhibitors of second messengers of gene expression were examined by Northern blot analysis.Expression of mRNA for gamma-glutamylcysteine synthetase (gamma-GCS), a rate-limiting enzyme of the de novo glutathione synthesis pathway, was elevated much more than that of glutathione reductase (GR) mRNA after exposure to 50cGy gamma-rays. The low-dose gamma-ray-induced gamma-GCS mRNA elevation was abolished by inhibitors of protein kinase C and protein tyrosine kinase, as well as by the calcium ion channel blocker, nifedipine. Calcium-related reagents, such BAPTA/AM and EGTA, chelators of intra- and extracellular Ca2+ respectively, and a Ca2+ ionophore (A23187), also strongly blocked the elevation of gamma-GCS mRNA expression induced by gamma-rays.The increase of intracellular glutathione in RAW 264.7 soon after low-dose gamma-ray exposure mainly occurs through the operation of the de novo pathway, following by the induction of gamma-GCS mRNA, for which elevation of intracellular calcium is required.