Mechanisms of IhERG/IKr Modulation by α1-Adrenoceptors in HEK293 Cells and Cardiac Myocytes
| Autor: | Aintzane Alday, José A. Sánchez-Chapula, Iván A. Aréchiga-Figueroa, L Layse Malagueta-Vieira, Janire Urrutia, Oscar Casis, Mónica Gallego |
|---|---|
| Jazyk: | angličtina |
| Rok vydání: | 2016 |
| Předmět: |
0301 basic medicine
Phosphatidylinositol 4 5-Diphosphate IKr Physiology hERG Cardiac metabolism Protein Serine-Threonine Kinases lcsh:Physiology lcsh:Biochemistry 03 medical and health sciences Phenylephrine Receptors Adrenergic alpha-1 Myocyte Animals Humans Myocytes Cardiac PKA lcsh:QD415-436 cardiovascular diseases Phosphorylation PKC Protein kinase C Protein Kinase C biology lcsh:QP1-981 Chemistry HEK 293 cells α1 adrenoceptor Potassium channel Ether-A-Go-Go Potassium Channels Cell biology Enzyme Activation 030104 developmental biology Delayed rectifier HEK293 Cells Potassium Channels Voltage-Gated Type C Phospholipases biology.protein Cats Phosphatidylinositol 4 5-bisphosphate Ion Channel Gating Signal Transduction Src |
| Zdroj: | Cellular Physiology and Biochemistry, Vol 40, Iss 6, Pp 1261-1273 (2016) |
| ISSN: | 1421-9778 1015-8987 |
| Popis: | Background: The rapid delayed rectifier K+ current (IKr), carried by the hERG protein, is one of the main repolarising currents in the human heart and a reduction of this current increases the risk of ventricular fibrillation. α1-adrenoceptors (α1-AR) activation reduces IKr but, despite the clear relationship between an increase in the sympathetic tone and arrhythmias, the mechanisms underlying the α1-AR regulation of the hERG channel are controversial. Thus, we aimed to investigate the mechanisms by which α1-AR stimulation regulates IKr. Methods: α1-adrenoceptors, hERG channels, auxiliary subunits minK and MIRP1, the non PIP2-interacting mutant D-hERG (with a deletion of the 883-894 amino acids) in the C-terminal and the non PKC-phosphorylable mutant N-terminal truncated-hERG (NTK-hERG) were transfected in HEK293 cells. Cell membranes were extracted by centrifugation and the different proteins were visualized by Western blot. Potassium currents were recorded by the patch-clamp technique. IKr was recorded in isolated feline cardiac myocytes. Results: Activation of the α1-AR reduces the amplitude of IhERG and IKr through a positive shift in the activation half voltage, which reduces the channel availability at physiological membrane potentials. The intracellular pathway connecting the α1-AR to the hERG channel in HEK293 cells includes activation of the Gαq protein, PLC activation and PIP2 hydrolysis, activation of PKC and direct phosphorylation of the hERG channel N-terminal. The PKC-mediated IKr channel phosphorylation and subsequent IKr reduction after α1-AR stimulation was corroborated in feline cardiac myocytes. Conclusions: These findings clarify the link between sympathetic nervous system hyperactivity and IKr reduction, one of the best characterized causes of torsades de pointes and ventricular fibrillation. |
| Databáze: | OpenAIRE |
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