TY - JOUR
T1 - Independent and interrelated regulation of ornithine decarboxylase by calcium and cAMP in fetal rat osteoblasts
AU - van Leeuwen, J. P.T.M.
AU - Bos, M. P.
AU - Herrmann-Erlee, M. P.M.
PY - 1988/8
Y1 - 1988/8
N2 - The present study was undertaken to determine in fetal rat osteoblasts whether and how the intracellular messengers calcium and cAMP are involved in stimulation of ornithine decarboxylase (ODC) activity. For that purpose we used different drugs affecting [Ca2+]i and cAMP concentration. A23187 stimulates ODC activity in a biphasic way, with maximal stimulation at 100 nM A23187. At that concentration no stimulation of cAMP production was observed. Basal and A23187-stimulated (100 nM) ODC activity were inhibited by EGTA and trifluoperazine. Forskolin stimulated dose-dependently both ODC activity and cAMP production. Besides these effects forskolin (1 and 10 μM) increased the [Ca2+]i via an increased calcium influx. Addition of La3+, verapamil or EGTA, but not of trifluoperazine, significantly inhibited the forskolin-stimulated (10 μM) ODC activity. When forskolin (100 nM and 1 μM) was added together with 1 μM A23187, a synergistic stimulation of ODC activity was observed. These results implicate that calcium is involved in basal ODC activity, and that ODC activity can be stimulated via (1) a cAMP-independent calcium pathway, and (2) a calcium-dependent, cAMP pathway. It is proposed that ODC activity can be stimulated via interaction between calcium and cAMP.
AB - The present study was undertaken to determine in fetal rat osteoblasts whether and how the intracellular messengers calcium and cAMP are involved in stimulation of ornithine decarboxylase (ODC) activity. For that purpose we used different drugs affecting [Ca2+]i and cAMP concentration. A23187 stimulates ODC activity in a biphasic way, with maximal stimulation at 100 nM A23187. At that concentration no stimulation of cAMP production was observed. Basal and A23187-stimulated (100 nM) ODC activity were inhibited by EGTA and trifluoperazine. Forskolin stimulated dose-dependently both ODC activity and cAMP production. Besides these effects forskolin (1 and 10 μM) increased the [Ca2+]i via an increased calcium influx. Addition of La3+, verapamil or EGTA, but not of trifluoperazine, significantly inhibited the forskolin-stimulated (10 μM) ODC activity. When forskolin (100 nM and 1 μM) was added together with 1 μM A23187, a synergistic stimulation of ODC activity was observed. These results implicate that calcium is involved in basal ODC activity, and that ODC activity can be stimulated via (1) a cAMP-independent calcium pathway, and (2) a calcium-dependent, cAMP pathway. It is proposed that ODC activity can be stimulated via interaction between calcium and cAMP.
UR - http://www.scopus.com/inward/record.url?scp=0023688178&partnerID=8YFLogxK
U2 - 10.1016/0143-4160(88)90022-X
DO - 10.1016/0143-4160(88)90022-X
M3 - Article
C2 - 2847870
AN - SCOPUS:0023688178
SN - 0143-4160
VL - 9
SP - 181
EP - 191
JO - Cell Calcium
JF - Cell Calcium
IS - 4
ER -