RT Journal Article SR Electronic T1 Muscarinic Receptor Activation Increases hERG Channel Expression through Phosphorylation of Ubiquitin Ligase Nedd4-2 JF Molecular Pharmacology JO Mol Pharmacol FD American Society for Pharmacology and Experimental Therapeutics SP 877 OP 886 DO 10.1124/mol.113.091553 VO 85 IS 6 A1 Tingzhong Wang A1 Andrew Hogan-Cann A1 Yudi Kang A1 Zhi Cui A1 Jun Guo A1 Tonghua Yang A1 Shawn M. Lamothe A1 Wentao Li A1 Aiqun Ma A1 John T. Fisher A1 Shetuan Zhang YR 2014 UL http://molpharm.aspetjournals.org/content/85/6/877.abstract AB The human ether-à-go-go–related gene (hERG) encodes the pore-forming subunit of the rapidly activating delayed rectifier potassium channel, which is important for cardiac repolarization. Reduction of hERG current due to genetic mutations or drug interferences causes long QT syndrome, leading to cardiac arrhythmias and sudden death. To date, there is no effective therapeutic method to restore or enhance hERG channel function. Using cell biology and electrophysiological methods, we found that the muscarinic receptor agonist carbachol increased the expression and function of hERG, but not ether-à-go-go or Kv1.5 channels stably expressed in human embryonic kidney cells. The carbachol-mediated increase in hERG expression was abolished by the selective M3 antagonist 4-DAMP (1,1-dimethyl-4-diphenylacetoxypiperidinium iodide) but not by the M2 antagonist AF-DX 116 (11[[2-[(diethylamino)methyl]-1-piperidinyl]-acetyl]-5,11-dihydro-6H-pyrido[2,3-b] [1,4]benzodiazepine-6-one). Treatment of cells with carbachol reduced the hERG-ubiquitin interaction and slowed the rate of hERG degradation. We previously showed that the E3 ubiquitin ligase Nedd4-2 mediates degradation of hERG channels. Here, we found that disrupting the Nedd4-2 binding domain in hERG completely eliminated the effect of carbachol on hERG channels. Carbachol treatment enhanced the phosphorylation level, but not the total level, of Nedd4-2. Blockade of the protein kinase C (PKC) pathway abolished the carbachol-induced enhancement of hERG channels. Our data suggest that muscarinic activation increases hERG channel expression by phosphorylating Nedd4-2 via the PKC pathway.