Time-dependent effects of parathyroid hormone and prostaglandin E2 on DNA synthesis by periosteal cells from embryonic chick calvaria.
Both PGE2 and PTH (1-34) caused a time- and concentration-dependent stimulation of proliferation by embryonic chick periosteal cells. Cells were exposed to the agents for different periods of time, the medium was replaced with fresh medium, and 3H-TdR incorporation was measured after 16 hours. Challenge with 10(-6) M prostaglandin E2 (PGE2) or 10(-7) M parathyroid hormone (1-34) (PTH) for 5 minutes produced 4- and 5.5-fold increases in 3H-TdR incorporation, respectively. Longer exposures, however, produced diminishing responses and after 45 minutes, only minimal effects or slight inhibitions were seen. These time-dependent effects were also seen with forskolin and dibutyryl-cAMP; TPA on the other hand stimulated DNA synthesis after both short- and long-term exposure. Both PGE2 and PTH (1-34) stimulated cAMP synthesis in periosteal cells but neither could be shown to stimulate protein kinase-C (PKC) at concentrations required for stimulation of proliferation, and dibutyryl-cyclic AMP (cAMP) effectively inhibited endogenous PKC activity. It is possible that the stimulation of proliferation by short-term exposure to PGE2 and PTH (1-34) is mediated by cAMP and that the time dependency possibly stems from the inhibition of endogenous PKC activity by increased intracellular cAMP levels.
Scutt
A
A
Department of Genetics, Gesellschaft für Biotechnologische Forschung, Braunschweig, Germany.
Duvos
C
C
Lauber
J
J
Mayer
H
H
D000818:Animals; D002455:Cell Division / Q000187:drug effects / Q000502:physiology; D002478:Cells, Cultured; D002642:Chick Embryo; D000242:Cyclic AMP / Q000032:analysis; D004247:DNA / Q000378:metabolism*; D015232:Dinoprostone / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D010281:Parathyroid Hormone / Q000097:blood / Q000494:pharmacology*; D010521:Periosteum / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism*; D011493:Protein Kinase C / Q000502:physiology; D012886:Skull / Q000166:cytology* / Q000196:embryology* / Q000378:metabolism; D013997:Time Factors; D014316:Tritium
D010281:Parathyroid Hormone; D014316:Tritium; D004247:DNA; D000242:Cyclic AMP; D011493:Protein Kinase C; D015232:Dinoprostone