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Quinone-induced oxidative stress elevates glutathione and induces gamma-glutamylcysteine synthetase activity in rat lung epithelial L2 cells.
J Biol Chem 1994; 269(42):26512-7JB

Abstract

Glutathione (GSH) is one of the most important physiological antioxidants involved in detoxification of hydrogen peroxide and lipid hydroperoxide. Previous studies have shown that cells can maintain and even increase cellular GSH content in response to sublethal oxidative stress. We hypothesized that gamma-glutamylcysteine synthetase (gamma GCS), the rate-limiting enzyme in de novo GSH synthesis, could be induced by oxidative stress. Rat lung epithelial L2 cells were challenged with 2,3-dimethoxy-1,4-naphthoquinone (DMNQ), generates O2.- and H2O2 continuously through redox cycling. Exposure of confluent L2 cells with sublethal doses of DMNQ caused sustained elevation of cellular GSH levels over a 24-h period (to 2.5-fold with 10 microM). DMNQ caused increases in gamma GCS activity (70% at 24 h with 10 microM), the gamma GCS catalytic heavy subunit (gamma GCS-HS) protein level, and gamma GCS-HS mRNA content (approximately 4-fold after 6 h with 10 microM). The elevation of gamma GCS-HS mRNA by DMNQ was eliminated by co-incubation with actinomycin D. Nuclear run-on experiments demonstrated that the transcriptional rate of the gamma GCS-HS gene was increased by 3- or 6-h exposure to 10 microM DMNQ. Our results suggested that the induction of de novo GSH synthesis by naphthoquinone-induced oxidative stress is associated with the transcriptional activation of the gamma GCS-HS gene and the subsequent elevation in gamma GCS activity. Unlike simpler quinones, DMNQ cannot form a GSH conjugate. Thus, the induction of gamma GCS-HS gene transcription does not require formation of an electrophile-glutathione conjugate.

Authors+Show Affiliations

Department of Molecular Pharmacology and Toxicology, University of Southern California, Los Angeles 90033.No affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, U.S. Gov't, P.H.S.

Language

eng

PubMed ID

7929374

Citation

Shi, M M., et al. "Quinone-induced Oxidative Stress Elevates Glutathione and Induces Gamma-glutamylcysteine Synthetase Activity in Rat Lung Epithelial L2 Cells." The Journal of Biological Chemistry, vol. 269, no. 42, 1994, pp. 26512-7.
Shi MM, Kugelman A, Iwamoto T, et al. Quinone-induced oxidative stress elevates glutathione and induces gamma-glutamylcysteine synthetase activity in rat lung epithelial L2 cells. J Biol Chem. 1994;269(42):26512-7.
Shi, M. M., Kugelman, A., Iwamoto, T., Tian, L., & Forman, H. J. (1994). Quinone-induced oxidative stress elevates glutathione and induces gamma-glutamylcysteine synthetase activity in rat lung epithelial L2 cells. The Journal of Biological Chemistry, 269(42), pp. 26512-7.
Shi MM, et al. Quinone-induced Oxidative Stress Elevates Glutathione and Induces Gamma-glutamylcysteine Synthetase Activity in Rat Lung Epithelial L2 Cells. J Biol Chem. 1994 Oct 21;269(42):26512-7. PubMed PMID: 7929374.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Quinone-induced oxidative stress elevates glutathione and induces gamma-glutamylcysteine synthetase activity in rat lung epithelial L2 cells. AU - Shi,M M, AU - Kugelman,A, AU - Iwamoto,T, AU - Tian,L, AU - Forman,H J, PY - 1994/10/21/pubmed PY - 1994/10/21/medline PY - 1994/10/21/entrez SP - 26512 EP - 7 JF - The Journal of biological chemistry JO - J. Biol. Chem. VL - 269 IS - 42 N2 - Glutathione (GSH) is one of the most important physiological antioxidants involved in detoxification of hydrogen peroxide and lipid hydroperoxide. Previous studies have shown that cells can maintain and even increase cellular GSH content in response to sublethal oxidative stress. We hypothesized that gamma-glutamylcysteine synthetase (gamma GCS), the rate-limiting enzyme in de novo GSH synthesis, could be induced by oxidative stress. Rat lung epithelial L2 cells were challenged with 2,3-dimethoxy-1,4-naphthoquinone (DMNQ), generates O2.- and H2O2 continuously through redox cycling. Exposure of confluent L2 cells with sublethal doses of DMNQ caused sustained elevation of cellular GSH levels over a 24-h period (to 2.5-fold with 10 microM). DMNQ caused increases in gamma GCS activity (70% at 24 h with 10 microM), the gamma GCS catalytic heavy subunit (gamma GCS-HS) protein level, and gamma GCS-HS mRNA content (approximately 4-fold after 6 h with 10 microM). The elevation of gamma GCS-HS mRNA by DMNQ was eliminated by co-incubation with actinomycin D. Nuclear run-on experiments demonstrated that the transcriptional rate of the gamma GCS-HS gene was increased by 3- or 6-h exposure to 10 microM DMNQ. Our results suggested that the induction of de novo GSH synthesis by naphthoquinone-induced oxidative stress is associated with the transcriptional activation of the gamma GCS-HS gene and the subsequent elevation in gamma GCS activity. Unlike simpler quinones, DMNQ cannot form a GSH conjugate. Thus, the induction of gamma GCS-HS gene transcription does not require formation of an electrophile-glutathione conjugate. SN - 0021-9258 UR - https://www.unboundmedicine.com/medline/citation/7929374/Quinone_induced_oxidative_stress_elevates_glutathione_and_induces_gamma_glutamylcysteine_synthetase_activity_in_rat_lung_epithelial_L2_cells_ L2 - http://www.jbc.org/cgi/pmidlookup?view=long&pmid=7929374 DB - PRIME DP - Unbound Medicine ER -