Parathyroid hormone increases prostaglandin G/H synthase-2 transcription by a cyclic adenosine 3',5'-monophosphate-mediated pathway in murine osteoblastic MC3T3-E1 cells.
PTH increased PG synthase-2 transcription in osteoblastic MC3T3-E1 cells at 30 min, as assessed by nuclear run-on assays. To determine the signaling pathways used by PTH, the activity of a construct containing the PG synthase-2 gene between nucleotides -963 and +70 linked to a luciferase reporter was analyzed in stably transfected MC3T3-E1 cells. Agents that activate the cAMP-protein kinase A or protein kinase C pathways increased PG synthase-2 promoter activity. In contrast, the calcium ionophore ionomycin was ineffective. The protein kinase A inhibitor H89 blocked PTH stimulation of PG synthase-2 promoter activity, whereas an overnight pre-incubation with phorbol ester to down-regulate protein kinase C did not. PTH-(3-34), a peptide that has greatly reduced ability to activate the cAMP-protein kinase A pathway, did not increase PG synthase-2 transcription or promoter activity. PTH could induce PG synthase-2 messenger RNA accumulation and PG synthase-2 transcription in the presence of cycloheximide. In addition, PTH-stimulated PG synthase-2 transcription was maintained at a high level at 2 h in the presence of cycloheximide. We conclude that PTH rapidly increases PG synthase-2 transcription in MC3T3-E1 cells, mainly through a cAMP-protein kinase A-mediated pathway without the need for protein synthesis. In contrast, the attenuation of increased PG synthase-2 transcription by PTH requires de novo protein synthesis.
Tetradis
S
S
Department of Medicine, University of Connecticut Health Center, Farmington 06030, USA.
Pilbeam
C C
CC
Liu
Y
Y
Herschman
H R
HR
Kream
B E
BE
D000818:Animals; D002118:Calcium / Q000378:metabolism; D002460:Cell Line; D000242:Cyclic AMP / Q000378:metabolism*; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism; D003513:Cycloheximide / Q000494:pharmacology; D004790:Enzyme Induction / Q000187:drug effects; D051379:Mice; D010006:Osteoblasts / Q000201:enzymology*; D010281:Parathyroid Hormone / Q000494:pharmacology*; D010446:Peptide Fragments / Q000494:pharmacology*; D011451:Prostaglandin-Endoperoxide Synthases / Q000235:genetics*; D011493:Protein Kinase C / Q000378:metabolism; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology; D012333:RNA, Messenger / Q000378:metabolism; D015398:Signal Transduction; D014158:Transcription, Genetic / Q000187:drug effects*; D014162:Transfection
D010281:Parathyroid Hormone; D010446:Peptide Fragments; D011500:Protein Synthesis Inhibitors; D012333:RNA, Messenger; C025076:parathyroid hormone (1-34), bovine; D003513:Cycloheximide; D000242:Cyclic AMP; D011451:Prostaglandin-Endoperoxide Synthases; D017868:Cyclic AMP-Dependent Protein Kinases; D011493:Protein Kinase C; D002118:Calcium