EGFR tyrosine kinase regulates small-conductance Ca2+-activated K+ (hSKCa1) channels expressed in HEK-293 cells

Small conductance Ca2+-activated K+ (SKCa) channels are widely distributed in different tissues including the brain, pancreatic islets, myocardium, etc., and play an important role in controlling electrical activity and cellular functions. However, intracellular signal modulation of SKCa channels is not fully understood. The present study was designed to investigate the potential regulation of hSKCa1 channels by protein tyrosine kinases (PTKs) in HEK 293 cells expressing hSKCa1 (KCNN1) gene using approaches of whole-cell patch voltage-clamp, immunoprecipitation, Western blot, and mutagenesis. We found that hSKCa1 current was inhibited by the broad spectrum PTK inhibitor genistein, the selective EGFR (epidermal growth factor receptor) kinase inhibitors T25, and AG556, but not by the Src-family kinases inhibitor PP2. The inhibitory effect of these PTK inhibitors was significantly antagonized by the protein tyrosine phosphatases (PTPs) inhibitor orthovanadate. Tyrosine phosphorylation level of hSKCa1 channels was reduced by genistein, T25, and AG556. The reduced tyrosine phosphorylation was countered by orthovanadate. Interestingly, the mutant hSKCa1 channel with Y109F lost the inhibitory response to T25 or AG556, and showed a dramatic reduction of tyrosine phosphorylation level and a reduced current density. These results demonstrate the novel information that hSKCa1 channels are inhibited by genistein, T25, and AG556 via EGFR tyrosine kinase inhibition, which is related to the...
Source: BJ Cell - Category: Biochemistry Authors: Tags: BJ Signal Source Type: research