Open AccessTyrphostin AG 556 increases the activity of large conductance Ca 2+ ‐activated K + channels by inhibiting epidermal growth factor receptor tyrosine kinase
Author(s) -
Wang Yan,
Sun HaiYing,
Liu YingGuang,
Song Zheng,
She Gang,
Xiao GuoSheng,
Wang Yan,
Li GuiRong,
Deng XiuLing
Publication year - 2017
Publication title -
journal of cellular and molecular medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.44
H-Index - 130
eISSN - 1582-4934
pISSN - 1582-1838
DOI - 10.1111/jcmm.13103
Subject(s) - tyrosine kinase , tyrosine phosphorylation , genistein , chemistry , protein tyrosine phosphatase , phosphorylation , tyrosine kinase inhibitor , platelet derived growth factor receptor , receptor tyrosine kinase , iberiotoxin , microbiology and biotechnology , tyrosine , endocrinology , biology , signal transduction , medicine , potassium channel , biochemistry , receptor , growth factor , cancer
The present study was designed to investigate whether large conductance Ca 2+ ‐activated K + ( BK ) channels were regulated by epidermal growth factor ( EGF ) receptor ( EGFR ) tyrosine kinase. BK current and channel tyrosine phosphorylation level were measured in BK ‐ HEK 293 cells expressing both functional α‐subunits and the auxiliary β1‐subunits using electrophysiology, immunoprecipitation and Western blotting approaches, respectively, and the function of rat cerebral basilar arteries was determined with a wire myography system. We found that BK current in BK ‐ HEK 293 cells was increased by the broad spectrum protein tyrosine kinase ( PTK ) inhibitor genistein and the selective EGFR tyrosine kinase inhibitor AG 556, one of the known tyrphostin. The effect of genistein or AG 556 was antagonized by the protein tyrosine phosphatase ( PTP ) inhibitor orthovanadate. On the other hand, orthovanadate or EGF decreased BK current, and the effect was counteracted by AG 556. The tyrosine phosphorylation level of BK channels (α‐ and β1‐subunits) was increased by EGF and orthovanadate, while decreased by genistein and AG 556, and the reduced tyrosine phosphorylation of BK channels by genistein or AG 556 was reversed by orthovanadate. Interestingly, AG 556 induced a remarkable enhancement of BK current in rat cerebral artery smooth muscle cells and relaxation of pre‐contracted rat cerebral basilar arteries with denuded endothelium, and these effects were antagonized by the BK channel blocker paxilline or orthovanadate. These results demonstrate that tyrosine phosphorylation of BK channels by EGFR kinase decreases the channel activity, and inhibition of EGFR kinase by AG 556 enhances the channel activity and dilates rat cerebral basilar arteries.