A. Morales et al., TRANSCRIPTIONAL REGULATION OF THE HEAVY SUBUNIT CHAIN OF GAMMA-GLUTAMYLCYSTEINE SYNTHETASE BY IONIZING-RADIATION, FEBS letters, 427(1), 1998, pp. 15-20
Since glutathione (GSH) protects against oxidative stress, we determin
ed the regulation of cellular GSH by ionizing radiation in human hepat
oblastoma cells, HepG2, The levels of GSH increased in irradiated HepG
2 due to a greater gamma-glutamylcysteine synthetase (gamma-GCS) activ
ity, which was paralleled by gamma-GCS heavy subunit chain (gamma-GCS-
HS) mRNA levels, Transcription of deletion constructs of the gamma-GCS
-NS promoter cloned in a reporter vector was associated with activator
protein-1 (AP-1), consistent with the DNA binding of AP-1 in nuclear
extracts of irradiated HepG2, Hence, the transcriptional regulation of
gamma-GCS by ionizing radiation emerges as an adaptive mechanism, whi
ch may be of significance to control the consequences of the oxidative
stress induced by radiation. (C) 1998 Federation of European Biochemi
cal Societies.