QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) Submit a response Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Park, I-N. Articles by Kim, S. G. Search for Related Content PubMed PubMed Citation Articles by Park, I-N. Articles by Kim, S. G.

Ceramide Negatively Regulates Glutathione S-transferase Gene Transactivation via Repression of Hepatic Nuclear Factor-1 That Is Degraded by the Ubiquitin Proteasome System

National Research Laboratory, College of Pharmacy and Research Institute of Pharmaceutical Sciences, Seoul National University, Seoul, Korea

The level of cellular ceramide, an apoptotic rheostat, is increased by sphingomyelinase or de novo synthesis. The expression of the glutathione S-transferase (GST) gene, whose induction accounts for cell viability, is regulated by activation of CCAAT/enhancer binding protein- (C/EBP) and NF-E2-related factor-2 (Nrf2). Hepatic nuclear factor-1 (HNF1) is a transcription factor necessary for cell survival. This study investigated the role of HNF1 in GSTA2 gene transactivation, the ubiquitin proteasomal degradation of HNF1, and the inhibition of activating HNF1 by ceramide for GSTA2 repression. C2-ceramide (C2), a cell-permeable analog, repressed the GSTA2 expression in H4IIE cells, whereas dihydro-C2, an inactive analog, had no effect. Immunoblot, immunocytochemical, and gel shift analyses revealed that C2 decreased the level of nuclear HNF1 and protein binding to the HNF response element (HRE). Deletion of the HRE or the GSTA2 gene promoter region containing the HRE reduced luciferase reporter expression. Immunoprecipitation and immunoblot analyses showed that C2 decreased the level of ubiquitinated HNF1, which was reversed by treatment with MG132, a proteasome inhibitor. C2 suppressed GSTA2 induction by oltipraz via inhibition of inducible HNF1 DNA binding. The functional role of HRE for C2 repression of GSTA2 gene transactivation by oltipraz was verified by both the luciferase reporter gene expression and the transfection experiment with HNF-pGL-1651 lacking the HRE. C2 similarly repressed the induction of GSTA2 promoter-luciferase by tert-butylhydroquinone via HNF1 suppression, suggesting that constitutive HNF1 activation is required for GSTA2 induction. C2 also inhibited GSTA3/5 expression. In conclusion, the HRE in the GSTA2 promoter region is functionally active for the constitutive and inducible gene expression, and ceramide inhibits GST gene transactivation through decrease in nuclear HNF1, which is degraded by the ubiquitin proteasome system.

Received December 19, 2003; accepted March 2, 2004.

Address correspondence to: Dr. Sang Geon Kim, College of Pharmacy, Seoul National University, Sillim-dong, Kwanak-gu, Seoul 151-742, South Korea. E-mail: sgk{at}snu.ac.kr

This article has been cited by other articles:

				Y.-Y. Liu, J. Y. Yu, D. Yin, G. A. Patwardhan, V. Gupta, Y. Hirabayashi, W. M. Holleran, A. E. Giuliano, S. M. Jazwinski, V. Gouaze-Andersson, et al. A role for ceramide in driving cancer cell resistance to doxorubicin FASEB J, July 1, 2008; 22(7): 2541 - 2551. [Abstract] [Full Text] [PDF]

				S. G. Kim and S. J. Lee PI3K, RSK, and mTOR Signal Networks for the GST Gene Regulation Toxicol. Sci., April 1, 2007; 96(2): 206 - 213. [Abstract] [Full Text] [PDF]

				L. Ng, K. Nichols, K. O'Rourke, A. Maslen, and G. M. Kirby Repression of Human GSTA1 by Interleukin-1beta Is Mediated by Variant Hepatic Nuclear Factor-1C Mol. Pharmacol., January 1, 2007; 71(1): 201 - 208. [Abstract] [Full Text] [PDF]

				L. Romero, L. Ng, and G. M. Kirby Chemical Inducers of Rodent Glutathione S-Transferases Down-Regulate Human GSTA1 Transcription through a Mechanism Involving Variant Hepatic Nuclear Factor 1-C Mol. Pharmacol., July 1, 2006; 70(1): 277 - 286. [Abstract] [Full Text] [PDF]

				S. H. Ki, I. J. Cho, D. W. Choi, and S. G. Kim Glucocorticoid Receptor (GR)-Associated SMRT Binding to C/EBP{beta} TAD and Nrf2 Neh4/5: Role of SMRT Recruited to GR in GSTA2 Gene Repression Mol. Cell. Biol., May 15, 2005; 25(10): 4150 - 4165. [Abstract] [Full Text] [PDF]

				I-N. Park, I. J. Cho, and S. G. Kim CERAMIDE, AN APOPTOTIC RHEOSTAT, INHIBITS CCAAT/ENHANCER BINDING PROTEIN-{beta} AND NF-E2-RELATED FACTOR-2 ACTIVATION: THE ROLE IN GLUTATHIONE S-TRANSFERASE A2 GENE REPRESSION Drug Metab. Dispos., September 1, 2004; 32(9): 893 - 897. [Abstract] [Full Text] [PDF]