Regulation of glutathione S-transferase gene expression by phenobarbital in cultured adult rat hepatocytes.
Previous studies, by using Northern blotting analyses, showed that phenobarbital (PB) affects the steady-state mRNA levels of glutathione S-transferase (GST) subunits 1/2, 3/4 and 7 in both conventional cultures of adult rat hepatocytes and co-cultures, with rat liver epithelial cells [Vandenberghe et al., 1989, FEBS Lett. 251, 59-64; Morel et al., 1989, FEBS Lett. 258, 99-102]. To determine whether PB acts at the transcriptional level, nuclear 'run on' experiments using cDNA probes hybridizing to GST subunits 1/2, 3/4 and 7 mRNA were performed on purified nuclei isolated from control and PB treated hepatocytes seeded under conventional and co-culture conditions. Data from this study demonstrate that the increase in steady-state mRNA levels observed in both conventional culture and co-culture after 4 days PB exposure results from an increased transcriptional activity of the GST genes. However, a substantial increase in steady-state mRNA levels in the absence of a commensurate increase in transcriptional activity at 12 days of co-culture, indicates that the barbiturate has also a stabilizing effect in vitro on the GST mRNAs.
Vandenberghe
Y
Y
Department of Toxicology, Vrije Universiteit Brussel, Belgium.
Tee
L
L
Morel
F
F
Rogiers
V
V
Guillouzo
A
A
Yeoh
G
G
D000818:Animals; D002478:Cells, Cultured; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects*; D005982:Glutathione Transferase / Q000235:genetics* / Q000378:metabolism; D008099:Liver / Q000166:cytology / Q000201:enzymology*; D010634:Phenobarbital / Q000494:pharmacology*; D051381:Rats; D011919:Rats, Inbred Strains; D014158:Transcription, Genetic
D005982:Glutathione Transferase; D010634:Phenobarbital