Human Ether á-go-go Gene Potassium Channels Are Regulated by EGFR Tyrosine Kinase

Abstract

Human ether á-go-go gene potassium channels (hEAG1) are expressed in brain and several types of human cancers and play a critical role in neuronal excitement and tumor progression. However, functional regulation of hEAG1 channels is not understood. The present study was designed to determine whether hEAG1 channels are regulated by EGFR kinase in HEK 293 cells expressing hEAG1 gene using a whole-cell patch clamp technique and a site-directed mutagenesis. It was found that EGF (100 ng/ml) slightly increased hEAG1 current in HEK 293 cells expressing WT-hEAG1. AG556 (an inhibitor of EGFR kinase) suppressed hEAG1 current in a concentration-dependent manner. The inhibitory effect was fully countered by 1 mM orthovanadate (an inhibitor of protein tyrosine phosphatases). The inhibitory effect of hEAG1 current by 10 μM AG556 (WT: 63.6±6.0%, n=6) was highly attenuated in the mutant hEAG1-Y90A (33.7±3.7%, n=7, P<0.001 vs WT), Y344A (33.1±6.0%, n=5, P<0.005 vs WT) and Y485A (21.5±3.8%, n=5, P<0.001 vs WT), but not Y376A (61.7±5.6%, n=6). These results demonstrate for the first that EGFR kinase modulates hEAG1 channel activity via phosphorylating tyrosine residues Tyr90, Try344 and Try485 and likely regulates neuronal activity and tumor growth.