Prostaglandin E2-induced up-regulation of c-fos messenger ribonucleic acid is primarily mediated by 3',5'-cyclic adenosine monophosphate in MC3T3-E1 osteoblasts.
The mechanism by which the proto-oncogene, c-fos, is up-regulated in response to PGE2 in the mouse osteoblastic (MC3T3-E1) cell line was investigated using RT-PCR. c-fos messenger RNA up-regulation by dmPGE2 is rapid, starting 10 min post stimulation, and transient. The specific protein kinase A (PKA) inhibitor, H89, inhibited c-fos induction. Moreover, down-regulation of protein kinase C (PKC) activity by chronic TPA treatment had no effect on the induction of c-fos by dmPGE2. We conclude that up-regulation of c-fos by dmPGE2 is primarily dependent on PKA in MC3T3-E1 osteoblasts. In S49 lymphoma wild-type but not S49 cyc- cells, which are deficient in cAMP signaling, dmPGE2 up-regulates c-fos and increases cell growth compared with unstimulated cells. Thus in S49 lymphoma cells, c-fos induction by PGE2 is also dependent on cAMP signaling. The minimal c-fos promoter region required for dmPGE2-induced expression was identified by transfecting c-fos promoter deletion constructs coupled to the chloramphenicol acetyltransferase (CAT) reporter gene into Vero cells. Transfection of a plasmid containing 99 bp c-fos proximal promoter was sufficient to direct c-fos/CAT expression following stimulation with dmPGE2. Because induction of c-fos is mediated by cAMP, these data are consistent with activation of c-fos via the CRE/ATF cis element.
Fitzgerald
J
J
University of California, Department of Medicine, Veterans Affairs Medical Center, San Francisco 94121, USA.
Dietz
T J
TJ
Hughes-Fulford
M
M
D000818:Animals; D002460:Cell Line; D002522:Chlorocebus aethiops; D000242:Cyclic AMP / Q000502:physiology*; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism; D015232:Dinoprostone / Q000494:pharmacology*; D017930:Genes, Reporter / Q000235:genetics; D016762:Genes, fos / Q000187:drug effects*; D006801:Humans; D051379:Mice; D010011:Osteocytes / Q000187:drug effects / Q000378:metabolism*; D011401:Promoter Regions, Genetic / Q000235:genetics; D011493:Protein Kinase C / Q000378:metabolism; D000090063:Proto-Oncogene Mas; D012333:RNA, Messenger / Q000096:biosynthesis*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014162:Transfection; D015854:Up-Regulation / Q000187:drug effects*; D014709:Vero Cells
C000715470:MAS1 protein, human; D000090063:Proto-Oncogene Mas; D012333:RNA, Messenger; D000242:Cyclic AMP; D017868:Cyclic AMP-Dependent Protein Kinases; D011493:Protein Kinase C; D015232:Dinoprostone