Induction of glutathione S-transferase P-form in primary cultured rat hepatocytes by epidermal growth factor and insulin.
The effects of epidermal growth factor (EGF) (10 ng/ml) and insulin (100 nM) on the expression of glutathione S-transferases (GSTs), especially the GST-P form (GST 7-7), were examined in primary cultured rat hepatocytes in serum-free medium. On culture with EGF and insulin, the GST activities towards 1-chloro-2,4-dinitrobenzene and 1,2-dichloro-4-nitrobenzene were transiently decreased on day 2 to 10% of those of freshly isolated hepatocytes and then increased to 60 to 100% of those of freshly isolated cells on day 4. Western blot analysis of GSTs revealed that GST-P, which is not present in freshly isolated hepatocytes, was markedly induced and that GST subunits 3 and 4 of the Mu class also increased after addition of EGF and/or insulin, while the subunits 1 and 2 of the Alpha class disappeared. Northern blot analysis showed that on addition of EGF and insulin the level of GST-P mRNA was also elevated and expressions of the nuclear oncogenes c-jun and c-fos were enhanced. These results suggest that the enhanced expression of GST-P induced by EGF or insulin in primary cultured rat hepatocytes might be regulated by JUN and FOS proteins.
Hatayama
I
I
Second Department of Biochemistry, Hirosaki University School of Medicine.
Yamada
Y
Y
Tanaka
K
K
Ichihara
A
A
Sato
K
K
D000818:Animals; D002478:Cells, Cultured; D004268:DNA-Binding Proteins / Q000235:genetics; D004790:Enzyme Induction; D004815:Epidermal Growth Factor / Q000494:pharmacology*; D015870:Gene Expression / Q000502:physiology; D005982:Glutathione Transferase / Q000096:biosynthesis* / Q000235:genetics / Q000378:metabolism; D007328:Insulin / Q000494:pharmacology*; D007527:Isoenzymes / Q000096:biosynthesis* / Q000235:genetics / Q000378:metabolism; D008099:Liver / Q000166:cytology / Q000187:drug effects / Q000201:enzymology*; D008297:Male; D011518:Proto-Oncogene Proteins / Q000235:genetics; D016760:Proto-Oncogene Proteins c-fos; D016755:Proto-Oncogene Proteins c-jun; D051381:Rats; D011919:Rats, Inbred Strains; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D014157:Transcription Factors / Q000235:genetics; D014158:Transcription, Genetic / Q000187:drug effects; D016212:Transforming Growth Factor beta / Q000494:pharmacology
D004268:DNA-Binding Proteins; D007328:Insulin; D007527:Isoenzymes; D011518:Proto-Oncogene Proteins; D016760:Proto-Oncogene Proteins c-fos; D016755:Proto-Oncogene Proteins c-jun; D014157:Transcription Factors; D016212:Transforming Growth Factor beta; D004815:Epidermal Growth Factor; D005982:Glutathione Transferase; D013755:Tetradecanoylphorbol Acetate