Endothelin‐1 modulates calcium signaling by epidermal growth factor, α‐thrombin, and prostaglandin E1 in UMR‐106 osteoblastic cells

Agnes Tatrai, Paula H. Stern*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

13 Scopus citations

Abstract

Local factors play an important role in the regulation of bone metabolism. The homologous and heterologous desensitization of responses to these factors may be crucial in the modulation of bone cell signaling. In this study, the effects and interactions of endothelin‐1 (25 nM), α‐thrombin (0.9 μM), epidermal growth factor (40 nM), prostaglandin E1 (5 μM), and prostaglandin F (5 μM) were examined on calcium signaling in UMR‐106 rat osteoblastic osteosarcoma cells. Intracellular calcium was measured using fluo‐3 fluorescent dye. All agents elicited calcium transients at these concentrations and showed homologous desensitization to their repeated administration. Preincubation for 60 minutes with 500 μM monodansylcadaverine and 30 minutes or 24 h preincubation with 0.5 μM indomethacin did not affect homologous desensitization, suggesting that neither the internalization of receptors nor prostaglandins are involved in this event. Pretreatment for 3 minutes with 2 μM 4β‐phorbol‐12β,13α‐dibutyrate significantly reduced the calcium elevations elicited by the first application of these compounds, whereas an inactive phorbol, 12,13‐didecanoate, had no effect. Pretreatment for 4 minutes with 0.5 μM forskolin decreased the calcium signal response to PGE, only. Pretreatment with endothelin‐1 for 3 minutes significantly decreased the calcium signals elicited by epidermal growth factor and α‐thrombin. Prior administration of endothelin‐1 significantly increased prostaglandin E1‐stimulated calcium transients, whereas prostaglandin F responses were not affected. Preincubation with indomethacin did not alter any of the interactions. Responses to endothelin‐1 were not significantly altered by 2–3 minutes pretreatment with the other factors, nor was there cross‐desensitization among the other factors. The results could indicate that endothelin‐1 has a unique and specific role in the modulation of bone cell signaling.

Original languageEnglish (US)
Pages (from-to)943-952
Number of pages10
JournalJournal of Bone and Mineral Research
Volume8
Issue number8
DOIs
StatePublished - Aug 1993

ASJC Scopus subject areas

  • Endocrinology, Diabetes and Metabolism
  • Orthopedics and Sports Medicine

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