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Effect of ethanol and high-fat feeding on hepatic gamma-glutamylcysteine synthetase subunit expression in the rat.
Hepatology. 1999 Jul; 30(1):209-14.Hep

Abstract

Glutathione (GSH) is important in antioxidant defense. A major determinant of the rate of GSH synthesis is the activity of the rate-limiting enzyme, gamma-glutamylcysteine synthetase (GCS). A heavy (HS) and light subunit (LS) make up GCS; oxidative stress regulates both transcriptionally. Cis-acting elements important for the oxidative stress-induced transcriptional up-regulation of both subunits are antioxidant response element (ARE) and activator protein-1 (AP-1). Nuclear factor-kappaB (NF-kappaB) may also regulate the heavy subunit. Chronic ethanol ingestion causes oxidative stress, increases AP-1 expression, and depletes hepatic GSH. Data conflict regarding GSH synthesis and are lacking regarding GCS subunit gene expression. We examined the effect of chronic ethanol ingestion on ARE, AP-1, and NF-kappaB activity and GCS subunit expression. Male Wistar rats were fed an ethanol and high-fat (28.7% cal) diet intragastrically for 9 weeks. Liver GSH level fell by 40%, although GCS activity doubled. GCS-HS mRNA level doubled, whereas GCS-LS mRNA level remained unchanged. Electrophoretic mobility shift assay (EMSA) showed that binding to ARE, AP-1, and NF-kappaB probes all increased. In conclusion, chronic ethanol ingestion increased GCS-HS expression and GCS activity by activating cis-acting elements important for transcriptional up-regulation of GCS-HS. GCS-LS mRNA level remained unchanged despite activation of ARE and AP-1, suggesting that negative transcriptional factors may be involved or the mRNA may be unstable. Despite induction in GCS activity, GSH level fell because of alterations in the other factors important in determining the steady-state GSH level.

Authors+Show Affiliations

Division of Gastroenterology and Liver Diseases, USC Liver Disease Research Center, USC School of Medicine, Los Angeles, CA, USA. shellylu@hsc.usc.eduNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

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

Language

eng

PubMed ID

10385658

Citation

Lu, S C., et al. "Effect of Ethanol and High-fat Feeding On Hepatic Gamma-glutamylcysteine Synthetase Subunit Expression in the Rat." Hepatology (Baltimore, Md.), vol. 30, no. 1, 1999, pp. 209-14.
Lu SC, Huang ZZ, Yang JM, et al. Effect of ethanol and high-fat feeding on hepatic gamma-glutamylcysteine synthetase subunit expression in the rat. Hepatology. 1999;30(1):209-14.
Lu, S. C., Huang, Z. Z., Yang, J. M., & Tsukamoto, H. (1999). Effect of ethanol and high-fat feeding on hepatic gamma-glutamylcysteine synthetase subunit expression in the rat. Hepatology (Baltimore, Md.), 30(1), 209-14.
Lu SC, et al. Effect of Ethanol and High-fat Feeding On Hepatic Gamma-glutamylcysteine Synthetase Subunit Expression in the Rat. Hepatology. 1999;30(1):209-14. PubMed PMID: 10385658.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Effect of ethanol and high-fat feeding on hepatic gamma-glutamylcysteine synthetase subunit expression in the rat. AU - Lu,S C, AU - Huang,Z Z, AU - Yang,J M, AU - Tsukamoto,H, PY - 1999/7/1/pubmed PY - 1999/7/1/medline PY - 1999/7/1/entrez SP - 209 EP - 14 JF - Hepatology (Baltimore, Md.) JO - Hepatology VL - 30 IS - 1 N2 - Glutathione (GSH) is important in antioxidant defense. A major determinant of the rate of GSH synthesis is the activity of the rate-limiting enzyme, gamma-glutamylcysteine synthetase (GCS). A heavy (HS) and light subunit (LS) make up GCS; oxidative stress regulates both transcriptionally. Cis-acting elements important for the oxidative stress-induced transcriptional up-regulation of both subunits are antioxidant response element (ARE) and activator protein-1 (AP-1). Nuclear factor-kappaB (NF-kappaB) may also regulate the heavy subunit. Chronic ethanol ingestion causes oxidative stress, increases AP-1 expression, and depletes hepatic GSH. Data conflict regarding GSH synthesis and are lacking regarding GCS subunit gene expression. We examined the effect of chronic ethanol ingestion on ARE, AP-1, and NF-kappaB activity and GCS subunit expression. Male Wistar rats were fed an ethanol and high-fat (28.7% cal) diet intragastrically for 9 weeks. Liver GSH level fell by 40%, although GCS activity doubled. GCS-HS mRNA level doubled, whereas GCS-LS mRNA level remained unchanged. Electrophoretic mobility shift assay (EMSA) showed that binding to ARE, AP-1, and NF-kappaB probes all increased. In conclusion, chronic ethanol ingestion increased GCS-HS expression and GCS activity by activating cis-acting elements important for transcriptional up-regulation of GCS-HS. GCS-LS mRNA level remained unchanged despite activation of ARE and AP-1, suggesting that negative transcriptional factors may be involved or the mRNA may be unstable. Despite induction in GCS activity, GSH level fell because of alterations in the other factors important in determining the steady-state GSH level. SN - 0270-9139 UR - https://www.unboundmedicine.com/medline/citation/10385658/Effect_of_ethanol_and_high_fat_feeding_on_hepatic_gamma_glutamylcysteine_synthetase_subunit_expression_in_the_rat_ L2 - https://linkinghub.elsevier.com/retrieve/pii/S0270913999003286 DB - PRIME DP - Unbound Medicine ER -