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Genistein and tyrphostin AG556 decrease ultra‐rapidly activating delayed rectifier K + current of human atria by inhibiting EGF receptor tyrosine kinase
Author(s) -
Xiao GuoSheng,
Zhang YanHui,
Wu Wei,
Sun HaiYing,
Wang Yan,
Li GuiRong
Publication year - 2017
Publication title -
british journal of pharmacology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.432
H-Index - 211
eISSN - 1476-5381
pISSN - 0007-1188
DOI - 10.1111/bph.13710
Subject(s) - genistein , immunoprecipitation , tyrosine kinase , tyrosine kinase inhibitor , proto oncogene tyrosine protein kinase src , protein tyrosine phosphatase , hek 293 cells , tyrosine phosphorylation , phosphorylation , inward rectifier potassium ion channel , patch clamp , microbiology and biotechnology , chemistry , receptor tyrosine kinase , biology , signal transduction , receptor , medicine , endocrinology , biochemistry , ion channel , cancer , gene
Background and Purpose The ultra‐rapidly activating delayed rectifier K + current I Kur (encoded by K v 1.5 or KCNA5 ) plays an important role in human atrial repolarization. The present study investigates the regulation of this current by protein tyrosine kinases (PTKs). Experimental Approach Whole‐cell patch voltage clamp technique and immunoprecipitation and Western blotting analysis were used to investigate whether the PTK inhibitors genistein, tyrphostin AG556 (AG556) and PP2 regulate human atrial I Kur and hKv1.5 channels stably expressed in HEK 293 cells. Key Results Human atrial I Kur was decreased by genistein (a broad‐spectrum PTK inhibitor) and AG556 (a highly selective EGFR TK inhibitor) in a concentration‐dependent manner. Inhibition of I Kur induced by 30 μM genistein or 10 μM AG556 was significantly reversed by 1 mM orthovanadate (a protein tyrosine phosphatase inhibitor). Similar results were observed in HEK 293 cells stably expressing hK v 1.5 channels. On the other hand, the Src family kinase inhibitor PP2 (1 μM) slightly enhanced I Kur and hK v 1.5 current, and the current increase was also reversed by orthovanadate. Immunoprecipitation and Western blotting analysis showed that genistein, AG556, and PP2 decreased tyrosine phosphorylation of hK v 1.5 channels and that the decrease was countered by orthovanadate. Conclusion and Implications The PTK inhibitors genistein and AG556 decrease human atrial I Kur and cloned hK v 1.5 channels by inhibiting EGFR TK, whereas the Src kinase inhibitor PP2 increases I Kur and hK v 1.5 current. These results imply that EGFR TK and the soluble Src kinases may have opposite effects on human atrial I Kur .