Regulation of an ERG K+ current by Src tyrosine kinase.
The human "ether-a-go-go"-related gene (HERG) K(+) channel, and its homologues are present in heart, neuronal tissue, some cancer cells, and the MLS-9 rat microglia cell line (Zhou, W., Cayabyab, F. S., Pennefather, P. S., Schlichter, L. C., and DeCoursey, T. E. (1998) J. Gen. Physiol. 111, 781-794). Despite its importance, there are few studies of ERG modulation. In this first report of regulation by tyrosine phosphorylation we show that MLS-9 cells express transcripts for r-erg1 (rat homologue of HERG) and r-erg2, and an immunoreactive doublet was identified using an anti-HERG antibody. The constitutive tyrosine phosphorylation of the ERG1 protein, detected by co-immunoprecipitation, was reduced by the protein-tyrosine kinase inhibitors, lavendustin A, herbimycin A, or genistein (but not daidzein). The whole cell ERG current was reduced by protein-tyrosine kinase inhibitors or the Src-selective inhibitory peptide, src40-58, but not by a scrambled peptide. Conversely, the current was increased by the Src-activating peptide, srcpY, but not by an inactive analogue. Activating endogenous Src or transfecting constitutively active v-Src altered the voltage dependence and deactivation kinetics to produce more current at negative potentials. Co-immunoprecipitation identified an association between the channel protein and Src. Thus, r-ERG1 and Src tyrosine kinase appear to exist in a signaling complex that is well positioned to modulate this K(+) channel and affect its contribution to cellular functions.
Cayabyab
Francisco S
FS
Division of Cellular and Molecular Biology, Toronto Western Research Institute, University Health Network and Department of Physiology, University of Toronto, Toronto, Ontario M5T 2S8, Canada.
Schlichter
Lyanne C
LC
D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D016227:Benzoquinones; D015153:Blotting, Western; D027682:Cation Transport Proteins; D002460:Cell Line; D004268:DNA-Binding Proteins; D004305:Dose-Response Relationship, Drug; D000072237:ERG1 Potassium Channel; D004594:Electrophysiology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D051638:Ether-A-Go-Go Potassium Channels; D019833:Genistein / Q000494:pharmacology; D006801:Humans; D007700:Kinetics; D047029:Lactams, Macrocyclic; D010455:Peptides / Q000737:chemistry; D010636:Phenols / Q000494:pharmacology; D010766:Phosphorylation; D011188:Potassium / Q000378:metabolism*; D015221:Potassium Channels / Q000378:metabolism*; D024642:Potassium Channels, Voltage-Gated; D011233:Precipitin Tests; D011505:Protein-Tyrosine Kinases / Q000378:metabolism; D011809:Quinones / Q000494:pharmacology; D051381:Rats; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017828:Rifabutin / Q000031:analogs & derivatives; D015398:Signal Transduction; D013997:Time Factors; D015534:Trans-Activators; D000071230:Transcriptional Regulator ERG; D014162:Transfection; D014443:Tyrosine / Q000378:metabolism; D019061:src-Family Kinases / Q000378:metabolism*
D016227:Benzoquinones; D027682:Cation Transport Proteins; D004268:DNA-Binding Proteins; C072312:ERG protein, human; D000072237:ERG1 Potassium Channel; D004791:Enzyme Inhibitors; D051638:Ether-A-Go-Go Potassium Channels; C496884:KCNH1 protein, human; C000606913:KCNH2 protein, human; C092509:KCNH6 protein, human; D047029:Lactams, Macrocyclic; D010455:Peptides; D010636:Phenols; D015221:Potassium Channels; D024642:Potassium Channels, Voltage-Gated; D011809:Quinones; C573309:Src40-58 peptide; D015534:Trans-Activators; D000071230:Transcriptional Regulator ERG; D017828:Rifabutin; C062898:lavendustin A; D014443:Tyrosine; C020754:herbimycin; D000255:Adenosine Triphosphate; D019833:Genistein; D011505:Protein-Tyrosine Kinases; D019061:src-Family Kinases; D011188:Potassium