Differential effects of cholera toxin and pertussis toxin on the c-fos and c-jun mRNA expression in rat C6 glioma cells.
Cholera toxin (CTX) increased c-fos mRNA level whereas it down-regulated the c-jun mRNA level in rat C6 glioma cells. In contrast to the action of CTX, pertussis toxin (PTX) did not affect either c-fos or c-jun mRNA level. The elevated c-fos mRNA level induced by CTX was significantly inhibited by the co-treatment with dexamethasone (DEX). However, DEX did not affect CTX-induced down-regulation of c-jun mRNA level. Cycloheximide (CHX) increased c-fos and c-jun mRNA levels. CHX caused a super-induction of CTX-induced c-fos mRNA level. Our results suggest that CTX-, but not PTX-, sensitive G-proteins may play an important role for c-fos mRNA up-regulation and c-jun mRNA down-regulation. In addition, DEX appears to have a selective inhibitory action against c-fos mRNA expression regulated by CTX. Ongoing protein synthesis inhibition is required for the superinduction of c-fos, but not c-jun, mRNA induced by CTX.
Lee
J K
JK
Department of Pharmacology and Institute of Natural Medicine, College of Medicine, Hallym University, Chunchon, Korea.
Choi
M R
MR
Paek
S H
SH
Song
D K
DK
Huh
S O
SO
Kim
Y H
YH
Suh
H W
HW
D000818:Animals; D015152:Blotting, Northern; D002772:Cholera Toxin / Q000378:metabolism / Q000494:pharmacology*; D016895:Culture Media, Serum-Free; D003513:Cycloheximide / Q000494:pharmacology; D018076:DNA, Complementary; D003907:Dexamethasone / Q000494:pharmacology; D019204:GTP-Binding Proteins / Q000378:metabolism; D005786:Gene Expression Regulation / Q000187:drug effects*; D016762:Genes, fos; D016758:Genes, jun; D009457:Neuroglia / Q000166:cytology / Q000378:metabolism*; D037342:Pertussis Toxin; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D051381:Rats; D013997:Time Factors; D014407:Tumor Cells, Cultured; D010566:Virulence Factors, Bordetella / Q000378:metabolism / Q000494:pharmacology*
D016895:Culture Media, Serum-Free; D018076:DNA, Complementary; D012333:RNA, Messenger; D010566:Virulence Factors, Bordetella; D003907:Dexamethasone; D002772:Cholera Toxin; D003513:Cycloheximide; D037342:Pertussis Toxin; D019204:GTP-Binding Proteins