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Transforming growth factor-beta1 is a potent inhibitor of glutathione synthesis in the lung epithelial cell line A549: transcriptional effect on the GSH rate-limiting enzyme gamma-glutamylcysteine synthetase.
Am J Respir Cell Mol Biol. 1997 Nov; 17(5):599-607.AJ

Abstract

Glutathione (GSH) is an essential antioxidant tripeptide that protects mammalian cells against oxidants and xenobiotics. Patients with fibrotic lung disorders have very low levels of GSH in their alveolar epithelial lining fluid (ELF), whereas transforming growth factor (TGF)-beta is overexpressed in their alveolar epithelial cells. We observed that TGF-beta1 increased susceptibility of the human alveolar epithelial cell line A549 to H2O2-mediated cytotoxicity (P < 0.05), decreased the activities of the antioxidant enzymes glutathione reductase and catalase by 31%, and markedly decreased GSH content in A549 cells (P < 0.01). GSH depletion was associated with an equivalent decrease in the activity of the rate-limiting enzyme in GSH synthesis, gamma-glutamylcysteine synthetase (gamma-GCS) (P < 0.01). Western blot analysis confirmed that the loss of gamma-GCS activity was associated with a marked decrease in gamma-GCS heavy subunit (gamma-GCShs) protein. TGF-beta1 suppressed the steady-state level of messenger RNA (mRNA) for the gamma-GCShs gene, with a maximal effect at 24 h. The half-life of gamma-GCShs mRNA was not affected by TGF-beta1, but transcription of the gene was downregulated as determined with nuclear run-on assays. Our findings indicate for the first time that TGF-beta1 is a potent inhibitor of GSH synthesis in human lung epithelial cells, and that the inhibition is mediated, at least in part, by a transcriptional effect on the gene encoding gamma-GCShs. Regulation of gamma-GCShs gene expression by TGF-beta1 is likely to play an important role in lower respiratory tract GSH homeostasis, and may represent a novel target for therapeutic efforts in lung fibrosis.

Authors+Show Affiliations

Department of Medicine, Université of Sherbrooke, Quebec, Canada.No affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

9374111

Citation

Arsalane, K, et al. "Transforming Growth Factor-beta1 Is a Potent Inhibitor of Glutathione Synthesis in the Lung Epithelial Cell Line A549: Transcriptional Effect On the GSH Rate-limiting Enzyme Gamma-glutamylcysteine Synthetase." American Journal of Respiratory Cell and Molecular Biology, vol. 17, no. 5, 1997, pp. 599-607.
Arsalane K, Dubois CM, Muanza T, et al. Transforming growth factor-beta1 is a potent inhibitor of glutathione synthesis in the lung epithelial cell line A549: transcriptional effect on the GSH rate-limiting enzyme gamma-glutamylcysteine synthetase. Am J Respir Cell Mol Biol. 1997;17(5):599-607.
Arsalane, K., Dubois, C. M., Muanza, T., Bégin, R., Boudreau, F., Asselin, C., & Cantin, A. M. (1997). Transforming growth factor-beta1 is a potent inhibitor of glutathione synthesis in the lung epithelial cell line A549: transcriptional effect on the GSH rate-limiting enzyme gamma-glutamylcysteine synthetase. American Journal of Respiratory Cell and Molecular Biology, 17(5), 599-607.
Arsalane K, et al. Transforming Growth Factor-beta1 Is a Potent Inhibitor of Glutathione Synthesis in the Lung Epithelial Cell Line A549: Transcriptional Effect On the GSH Rate-limiting Enzyme Gamma-glutamylcysteine Synthetase. Am J Respir Cell Mol Biol. 1997;17(5):599-607. PubMed PMID: 9374111.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Transforming growth factor-beta1 is a potent inhibitor of glutathione synthesis in the lung epithelial cell line A549: transcriptional effect on the GSH rate-limiting enzyme gamma-glutamylcysteine synthetase. AU - Arsalane,K, AU - Dubois,C M, AU - Muanza,T, AU - Bégin,R, AU - Boudreau,F, AU - Asselin,C, AU - Cantin,A M, PY - 1997/11/28/pubmed PY - 1997/11/28/medline PY - 1997/11/28/entrez SP - 599 EP - 607 JF - American journal of respiratory cell and molecular biology JO - Am. J. Respir. Cell Mol. Biol. VL - 17 IS - 5 N2 - Glutathione (GSH) is an essential antioxidant tripeptide that protects mammalian cells against oxidants and xenobiotics. Patients with fibrotic lung disorders have very low levels of GSH in their alveolar epithelial lining fluid (ELF), whereas transforming growth factor (TGF)-beta is overexpressed in their alveolar epithelial cells. We observed that TGF-beta1 increased susceptibility of the human alveolar epithelial cell line A549 to H2O2-mediated cytotoxicity (P < 0.05), decreased the activities of the antioxidant enzymes glutathione reductase and catalase by 31%, and markedly decreased GSH content in A549 cells (P < 0.01). GSH depletion was associated with an equivalent decrease in the activity of the rate-limiting enzyme in GSH synthesis, gamma-glutamylcysteine synthetase (gamma-GCS) (P < 0.01). Western blot analysis confirmed that the loss of gamma-GCS activity was associated with a marked decrease in gamma-GCS heavy subunit (gamma-GCShs) protein. TGF-beta1 suppressed the steady-state level of messenger RNA (mRNA) for the gamma-GCShs gene, with a maximal effect at 24 h. The half-life of gamma-GCShs mRNA was not affected by TGF-beta1, but transcription of the gene was downregulated as determined with nuclear run-on assays. Our findings indicate for the first time that TGF-beta1 is a potent inhibitor of GSH synthesis in human lung epithelial cells, and that the inhibition is mediated, at least in part, by a transcriptional effect on the gene encoding gamma-GCShs. Regulation of gamma-GCShs gene expression by TGF-beta1 is likely to play an important role in lower respiratory tract GSH homeostasis, and may represent a novel target for therapeutic efforts in lung fibrosis. SN - 1044-1549 UR - https://www.unboundmedicine.com/medline/citation/9374111/Transforming_growth_factor_beta1_is_a_potent_inhibitor_of_glutathione_synthesis_in_the_lung_epithelial_cell_line_A549:_transcriptional_effect_on_the_GSH_rate_limiting_enzyme_gamma_glutamylcysteine_synthetase_ L2 - http://www.atsjournals.org/doi/full/10.1165/ajrcmb.17.5.2833?url_ver=Z39.88-2003&amp;rfr_id=ori:rid:crossref.org&amp;rfr_dat=cr_pub=pubmed DB - PRIME DP - Unbound Medicine ER -