Thromboxane A2-stimulated phospholipase D in osteoblast-like cells: Possible involvement of PKC

J. Shinoda, Atsushi Suzuki, Y. Oiso, O. Kozawa

Research output: Contribution to journalArticle

18 Citations (Scopus)

Abstract

We examined the effect of thromboxane A2 (TxA2) on phosphatidylcholine- hydrolyzing phospholipase D activity in osteoblast-like MC3T3-E1 cells. 9,11- Epithio-11,12-methanothromboxane A2 (STA2), a stable analogue of TxA2, stimulated the formations of both choline and inositol phosphates in a dose- dependent manner in the range between 10 nM and 10 μM. The formation of choline stimulated by a combination of STA2 and 12-O-tetradecanoylphorbol 13-acetate (TPA), a protein kinase C-activating phorbol ester, was not additive. 1-(5-Isoquinolinylsulfonyl)-2-methylpiperazine (H-7), an inhibitor of protein kinases, suppressed the formation of choline induced by STA2 as well as that by TPA, but 20 μM N-(2-guanidinoethyl)-5- isoquinolinesulfonamide (HA-1004), a control for H-7 as a protein kinase C inhibitor, had little effect. Calphostin C, a potent and specific inhibitor of protein kinase C, also suppressed the formation of choline induced by STA2. The STA2-induced formation of choline was significantly reduced by chelating extracellular Ca2+ with ethylene glycol-bis(β-aminoethyl ether)- N,N,N',N'-tetraacetic acid. STA2 dose dependently stimulated 45Ca2+ influx from extracellular space. STA2 stimulated DNA synthesis of MC3T3-E1 cells and increased the number of these cells. These results suggest that TxA2 stimulates phospholipase D in osteoblast-like cells, resulting in the direction of their proliferation, and that the activation of protein kinase C is involved in the stimulation of phospholipase D.

Original languageEnglish
JournalAmerican Journal of Physiology - Endocrinology and Metabolism
Volume269
Issue number3 32-3
Publication statusPublished - 01-01-1995
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Endocrinology, Diabetes and Metabolism
  • Physiology
  • Physiology (medical)

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