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Possible role of Na+influx in phorbol ester-induced down-regulation of protein kinase C in HL60 cells

Authors
Journal
FEBS Letters
0014-5793
Publisher
Wiley Blackwell (John Wiley & Sons)
Publication Date
Volume
328
Issue
3
Identifiers
DOI: 10.1016/0014-5793(93)80944-p
Keywords
  • Protein Kinase C
  • Down-Regulation
  • Na+/H+Exchanger
  • Hl60 Cell
Disciplines
  • Biology

Abstract

Abstract Amiloride, an inhibitor of Na +/H + exchange, inhibited down-regulation of protein kinase C in HL60 cells induced by tumor-promoting phorbol ester in dose-dependent manner judging from immunoblot analysis. This inhibition was observed with regard to type I (γ), type II (β), and type III (α) isozymes of protein kinase C. On the other hand, monensin, a Na + ionophore, accelerated the down-regulation of protein kinase C induced by phorbol ester. When we examined 22Na + uptake by HL60 cells, the higher uptake was observed after stimulation with phorbol ester compared to the control cells and this 22Na + uptake was strongly inhibited by the addition of amiloride. However, monensin further stimulated the 22Na + uptake observed in phorbol ester-treated cells. These data suggest that the increase in intracellular Na + concentration may be one of the triggers for the induction of down regulation of protein kinase C.

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