TY - JOUR
T1 - Phosphatidylcholine-specific phospholipase C inhibitor, tricyclodecan-9- yl xanthogenate (D609), increases phospholipase D-mediated phosphatidylcholine hydrolysis in UMR-106 osteoblastic osteosarcoma cells
AU - Singh, Amareshwar T.K.
AU - Radeff, Julie M.
AU - Kunnel, Joseph G.
AU - Stern, Paula H.
N1 - Funding Information:
This work was supported by a grant from the National Institutes of Health (AR-11262) to PHS.
PY - 2000/9/27
Y1 - 2000/9/27
N2 - Our previous studies have shown that parathyroid hormone (PTH) stimulates phosphatidylcholine (PC) hydrolysis by phospholipase D (PLD) and transphosphatidylation in UMR-106 osteoblastic cells. To determine whether phospholipase C (PLC) is also involved in the PTH-mediated PC hydrolysis, we used the inhibitor, tricyclodecan-9-yl xanthogenate (D609), a putatively selective antagonist of this pathway. Consistent with this proposed mechanism, D609 decreased 3H-phosphocholine in extracts from UMR-106 cells prelabeled with 3H-choline. Unexpectedly, D609 enhanced PC hydrolysis and transphosphatidylation, suggesting that either there was a compensatory increase in PLD activity when PLC was inhibited, or that D609 directly increased PLD activity. The D609-stimulated increase in PC hydrolysis was rapid, being seen as early as 2 min. The effect of D609 was temperature- sensitive, consistent with an enzymatic mechanism. The D609-stimulated increase in PC hydrolysis was PKC-independent, based upon the lack of effect of down-regulation of PKC by phorbol 12,13-dibutyrate on the response. The studies reveal a novel action of this inhibitor on signaling in osteoblastic cells which might influence downstream responses. (C) 2000 Elsevier Science B.V.
AB - Our previous studies have shown that parathyroid hormone (PTH) stimulates phosphatidylcholine (PC) hydrolysis by phospholipase D (PLD) and transphosphatidylation in UMR-106 osteoblastic cells. To determine whether phospholipase C (PLC) is also involved in the PTH-mediated PC hydrolysis, we used the inhibitor, tricyclodecan-9-yl xanthogenate (D609), a putatively selective antagonist of this pathway. Consistent with this proposed mechanism, D609 decreased 3H-phosphocholine in extracts from UMR-106 cells prelabeled with 3H-choline. Unexpectedly, D609 enhanced PC hydrolysis and transphosphatidylation, suggesting that either there was a compensatory increase in PLD activity when PLC was inhibited, or that D609 directly increased PLD activity. The D609-stimulated increase in PC hydrolysis was rapid, being seen as early as 2 min. The effect of D609 was temperature- sensitive, consistent with an enzymatic mechanism. The D609-stimulated increase in PC hydrolysis was PKC-independent, based upon the lack of effect of down-regulation of PKC by phorbol 12,13-dibutyrate on the response. The studies reveal a novel action of this inhibitor on signaling in osteoblastic cells which might influence downstream responses. (C) 2000 Elsevier Science B.V.
KW - Osteoblast
KW - Parathyroid hormone
KW - Phosphatidylcholine
KW - Phospholipase C
KW - Phospholipase D
KW - Protein kinase C
KW - Tricyclodecan-9-yl xanthogenate
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U2 - 10.1016/S1388-1981(00)00096-2
DO - 10.1016/S1388-1981(00)00096-2
M3 - Article
C2 - 11018472
AN - SCOPUS:0034721516
SN - 1388-1981
VL - 1487
SP - 201
EP - 208
JO - Biochimica et Biophysica Acta - Molecular and Cell Biology of Lipids
JF - Biochimica et Biophysica Acta - Molecular and Cell Biology of Lipids
IS - 2-3
ER -