Regulation of parathyroid hormone (PTH)/PTH-related peptide receptor messenger ribonucleic acid by glucocorticoids and PTH in ROS 17/2.8 and OK cells.
To study mechanisms controlling the expression of PTH/PTH-related peptide (PTHrP) receptors in ROS 17/2.8 and OK cells, we investigated the regulation of PTH/PTHrP receptor availability and receptor mRNA levels by glucocorticoids and PTH. Treatment of ROS 17/2.8 cells with dexamethasone (1 microM) for 2, 4, and 6 days increased specific binding of PTH to 148 +/- 12%, 203 +/- 10%, and 344 +/- 9% (mean +/- SD), respectively, compared to that in untreated control cells. PTH-stimulated cAMP accumulation also increased with dexamethasone treatment (1 microM) from 230 +/- 15%, 382 +/- 9%, and 820 +/- 9% after 2, 4 and 6 days, respectively, compared to that in untreated cells. Treatment of ROS 17/2.8 cells with [Nle8,Nle18,Tyr34]bovine PTH-(1-34) amide (NlePTH; 100 nM) alone or together with dexamethasone (1 microM), however, markedly decreased PTH binding and PTH-stimulated cAMP accumulation. Northern blot analysis showed that dexamethasone dramatically increased steady state levels of PTH/PTHrP receptor mRNA in a time- and dose-dependent manner, which did not occur when NlePTH (100 nM) was added concomitantly to the cultures. As previously reported, daily NlePTH treatment of ROS 17/2.8 cells reduced PTH/PTHrP receptor availability and PTH-stimulated cAMP accumulation markedly within 2 days, which remained at these low levels during continued PTH treatment. In contrast, the identical treatment reduced steady state levels of PTH/PTHrP receptor mRNA in ROS 17/2.8 transiently and to only a slight extent, which then returned to pretreatment levels. Treatment of OK cells with NlePTH (100 nM) for 1, 2, and 4 days decreased PTH binding to 56 +/- 6%, 44 +/- 4%, and 64 +/- 4% (mean +/- SD) and PTH-stimulated cAMP accumulation to 42 +/- 6%, 19 +/- 4%, and 21 +/- 3% (mean +/- SD), respectively, compared to values in untreated control cells. The same treatment, however, had no significant effect on steady state levels of PTH/PTHrP receptor transcripts. In contrast to its effects in ROS 17/2.8 cells, dexamethasone (1 microM) treatment of OK cells for 1-4 days did not affect PTH binding, nor did it significantly affect steady state levels of PTH/PTHrP receptor mRNA, although the latter was slightly lowered by dexamethasone treatment. PTH-stimulated cAMP accumulation was unchanged after 1-day treatment with dexamethasone and modestly rose to 142 +/- 4% of the control value by day 4 of glucocorticoid exposure.(ABSTRACT TRUNCATED AT 400 WORDS)
Ureña
P
P
Endocrine Unit, Massachusetts General Hospital, Boston 02114.
Iida-Klein
A
A
Kong
X F
XF
Jüppner
H
H
Kronenberg
H M
HM
Abou-Samra
A B
AB
Segre
G V
GV
D000818:Animals; D001483:Base Sequence; D002460:Cell Line; D000242:Cyclic AMP / Q000378:metabolism; D003907:Dexamethasone / Q000494:pharmacology*; D007668:Kidney / Q000166:cytology / Q000378:metabolism*; D008969:Molecular Sequence Data; D015345:Oligonucleotide Probes / Q000235:genetics; D009893:Opossums; D010281:Parathyroid Hormone / Q000494:pharmacology*; D010446:Peptide Fragments / Q000494:pharmacology; D012333:RNA, Messenger / Q000037:antagonists & inhibitors / Q000378:metabolism*; D018016:Receptors, Parathyroid Hormone / Q000037:antagonists & inhibitors / Q000235:genetics* / Q000378:metabolism; D019379:Teriparatide / Q000031:analogs & derivatives; D014407:Tumor Cells, Cultured; D015854:Up-Regulation / Q000187:drug effects
D015345:Oligonucleotide Probes; D010281:Parathyroid Hormone; D010446:Peptide Fragments; D012333:RNA, Messenger; D018016:Receptors, Parathyroid Hormone; D019379:Teriparatide; D003907:Dexamethasone; C061438:parathyroid hormone (1-34)amide, Nle(8), Nle(18), Tyr(34)-; D000242:Cyclic AMP