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Possible role of Na + influx in phorbol ester‐induced down‐regulation of protein kinase C in HL60 cells
Author(s) -
Takeuchi Noriko,
Hashimoto Eikichi,
Nakamura Toru,
Takeuchi Fumito,
Sada Kiyonao,
Yamamura Hirohei
Publication year - 1993
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(93)80944-p
Subject(s) - phorbol ester , protein kinase c , chemistry , protein kinase a , microbiology and biotechnology , hl60 , phorbol , kinase , biochemistry , biology , cell
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 22 Na + uptake by HL60 cells, the higher uptake was observed after stimulation with phorbol ester compared to the control cells and this 22 Na + uptake was strongly inhibited by the addition of amiloride. However, monensin further stimulated the 22 Na + 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.