TY - JOUR
T1 - Deubiquitylating enzyme USP2 counteracts Nedd4-2-mediated downregulation of KCNQ1 potassium channels
AU - Krzystanek, Katarzyna
AU - Rasmussen, Hanne Borger
AU - Grunnet, Morten
AU - Staub, Olivier
AU - Olesen, Søren-Peter
AU - Abriel, Hugues
AU - Jespersen, Thomas
N1 - Copyright © 2012 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.
PY - 2012/3
Y1 - 2012/3
N2 - Background: KCNQ1 (Kv7.1), together with its KCNE β subunits, plays a pivotal role both in the repolarization of cardiac tissue and in water and salt transport across epithelial membranes. Nedd4/Nedd4-like (neuronal precursor cellexpressed developmentally downregulated 4) ubiquitinprotein ligases interact with the KCNQ1 potassium channel through a PY motif located in the C terminus of KCNQ1. This interaction induces ubiquitylation of KCNQ1, resulting in a reduced surface density of the channel. It was reported recently that the epithelial sodium channel is regulated by the reverse process-deubiquitylation- mediated by USP2 (ubiquitin-specific protease 2). Objective: In this article, we investigated whether deubiquitylation may regulate KCNQ1 channel complexes. Methods: In this study, we used electrophysiology, biochemistry, and confocal microscopy. Results: Electrophysiological investigations of KCNQ1/KCNE1 proteins coexpressed with USP2-45 or USP2-69 isoforms and Nedd4-2 in Xenopus laevis oocytes and mammalian cells revealed that both USP2 isoforms counter the Nedd4-2specific downregulation of IKs. Biochemical studies showed that the total and surface-expressed KCNQ1 protein was more abundant when coexpressed with USP2 and Nedd4-2 as compared with Nedd4-2 alone. Western blotting revealed partial protection against covalent attachment of ubiquitin moieties on KCNQ1 when USP2 was coexpressed with Nedd4-2. Coimmunoprecipitation assays suggested that USP2 can bind to KCNQ1 independently of the PY motif. Immunocytochemistry confirmed that USP2 restores the membrane localization of KCNQ1. Conclusion: These results demonstrate that USP2 can be a potent regulator of KCNQ1 surface density. USP2, which is well expressed in many tissues, may therefore be important in controlling the KCNQ1 channel dynamics in vivo.
AB - Background: KCNQ1 (Kv7.1), together with its KCNE β subunits, plays a pivotal role both in the repolarization of cardiac tissue and in water and salt transport across epithelial membranes. Nedd4/Nedd4-like (neuronal precursor cellexpressed developmentally downregulated 4) ubiquitinprotein ligases interact with the KCNQ1 potassium channel through a PY motif located in the C terminus of KCNQ1. This interaction induces ubiquitylation of KCNQ1, resulting in a reduced surface density of the channel. It was reported recently that the epithelial sodium channel is regulated by the reverse process-deubiquitylation- mediated by USP2 (ubiquitin-specific protease 2). Objective: In this article, we investigated whether deubiquitylation may regulate KCNQ1 channel complexes. Methods: In this study, we used electrophysiology, biochemistry, and confocal microscopy. Results: Electrophysiological investigations of KCNQ1/KCNE1 proteins coexpressed with USP2-45 or USP2-69 isoforms and Nedd4-2 in Xenopus laevis oocytes and mammalian cells revealed that both USP2 isoforms counter the Nedd4-2specific downregulation of IKs. Biochemical studies showed that the total and surface-expressed KCNQ1 protein was more abundant when coexpressed with USP2 and Nedd4-2 as compared with Nedd4-2 alone. Western blotting revealed partial protection against covalent attachment of ubiquitin moieties on KCNQ1 when USP2 was coexpressed with Nedd4-2. Coimmunoprecipitation assays suggested that USP2 can bind to KCNQ1 independently of the PY motif. Immunocytochemistry confirmed that USP2 restores the membrane localization of KCNQ1. Conclusion: These results demonstrate that USP2 can be a potent regulator of KCNQ1 surface density. USP2, which is well expressed in many tissues, may therefore be important in controlling the KCNQ1 channel dynamics in vivo.
U2 - 10.1016/j.hrthm.2011.10.026
DO - 10.1016/j.hrthm.2011.10.026
M3 - Journal article
C2 - 22024150
SN - 1547-5271
VL - 9
SP - 440
EP - 448
JO - Heart Rhythm
JF - Heart Rhythm
IS - 3
ER -