Regulation of glucocorticoid-inducible hydroxysteroid sulfotransferase (SULT2A-40/41) gene transcription in primary cultured rat hepatocytes: role of CCAAT/enhancer-binding protein liver-enriched transcription factors.
The mechanism responsible for glucocorticoid receptor (GR)-mediated induction of rat hepatic hydroxysteroid sulfotransferase (SULT2A-40/41) gene transcription was investigated. We previously reported that the region of the SULT2A-40/41 5'-flanking region delimited by -158 to -77 nucleotides relative to the transcription start site was sufficient to support GR-inducible expression. This region of the SULT2A-40/41 gene does not contain a consensus glucocorticoid receptor-responsive element, but does contain two consensus sites for liver-enriched CCAAT/enhancer-binding protein (C/EBP) transcription factors. In the present study, incubation of primary cultured rat hepatocytes with a GR-activating concentration (10(-7) M) of a potent glucocorticoid, dexamethasone or triamcinolone acetonide (TA), rapidly produced increases in C/EBPalpha and C/EBPbeta nuclear protein contents, as measured by Western blot or in vitro DNA-binding activity analysis, that preceded increases in SULT2A-40/41 mRNA and protein levels. Transient cotransfection of SULT2A-40/41 reporter plasmids with a dominant negative C/EBP expression plasmid completely blocked TA-inducible SULT2A-40/41 reporter gene expression. Linker scanning and site-directed mutagenesis of the proximal SULT2A-40/41 5'-flanking region, complemented by in vitro DNA-binding analyses, indicated that the more distal C/EBP site was important for controlling SULT2A-40/41 promoter activity. These data support a role for GR-inducible C/EBPalpha and C/EBPbeta expression in the transactivation of hepatic SULT2A-40/41 expression.
Fang
Hai-Lin
HL
Institute of Environmental Health Sciences, Wayne State University, 2727 Second Avenue, Room 4000, Detroit, MI 48201, USA.
Abdolalipour
Masumeh
M
Duanmu
Zhengbo
Z
Smigelski
Jeffrey R
JR
Weckle
Amy
A
Kocarek
Thomas A
TA
Runge-Morris
Melissa
M
D000818:Animals; D022762:CCAAT-Enhancer-Binding Proteins / Q000502:physiology*; D002478:Cells, Cultured; D004790:Enzyme Induction / Q000187:drug effects / Q000502:physiology; D005938:Glucocorticoids / Q000494:pharmacology*; D022781:Hepatocytes / Q000187:drug effects / Q000201:enzymology*; D008099:Liver / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism*; D008297:Male; D051381:Rats; D017207:Rats, Sprague-Dawley; D015238:Sulfotransferases / Q000096:biosynthesis* / Q000235:genetics; D014157:Transcription Factors / Q000378:metabolism*; D014158:Transcription, Genetic / Q000187:drug effects / Q000502:physiology*
D022762:CCAAT-Enhancer-Binding Proteins; D005938:Glucocorticoids; D014157:Transcription Factors; D015238:Sulfotransferases; C028152:alcohol sulfotransferase