A Novel Mutation (T65P) in the PAS Domain of the Human Potassium Channel HERG Results in the Long QT Syndrome by Trafficking Deficiency

Paulussen, Aimée D C; Raes, Adam; Matthijs, Gert; Snyders, Dirk J.; Cohen, Nadine; Aerssens, Jeroen

doi:10.1074/jbc.m206569200

Cited by 89 publications

(98 citation statements)

References 40 publications

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“…Our data with hERG C66G and L86R are different from previous reports from oocytes that showed robust currents (14). The most likely explanation for differences in channel expression between oocytes (previous study) and HEK293 cells (this study) is a temperature-sensitive folding defect that is apparent with differences in culture temperature for oocytes (16°C) versus HEK293 cells (37°C), as described for other hERG LQT2 mutant channels (16,20,21,29).…”

Section: Discussioncontrasting

confidence: 56%

Rescue of Aberrant Gating by a Genetically Encoded PAS (Per-Arnt-Sim) Domain in Several Long QT Syndrome Mutant Human Ether-á-go-go-related Gene Potassium Channels

Gianulis

Trudeau

2011

Journal of Biological Chemistry

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Congenital long QT syndrome 2 (LQT2) is caused by loss-offunction mutations in the humanCongenital Long QT Syndrome (LQTS) 2 is a disorder of the electrical system of the heart characterized by delayed cardiac repolarization that can lead to arrhythmias, syncope, and sudden death (1). Type 2 LQTS (LQT2) is caused by genetic mutations in the human ether-á-go-go-related gene (hERG) (2-5). hERG encodes the major subunit of the rapidly activating delayed-rectifier potassium current (I Kr ), which plays an essential role in the final repolarization of the ventricular action potential (3, 4). hERG exhibits characteristic slow closing (deactivation) kinetics that are regulated by an N-terminal PerArnt-Sim (PAS) domain, which help to specialize the channels for their role in the heart (3, 6 -10).Loss of hERG function, and thus, loss of I Kr (11), can occur through a number of mechanisms, including defects in channel opening and closing (gating), ion permeation, or protein trafficking (12). hERG channels containing LQT2 mutations in the PAS domain (hERG PAS-LQT2) exhibit robust currents when studied in Xenopus oocytes (6, 13-15); however, most channels with LQT2 mutations located outside the PAS domain do not have measurable currents and show defects in maturation and trafficking when studied in mammalian cells (12, 16 -21). As only 5 hERG PAS-LQT2 channels have been functionally characterized in mammalian cells (20 -24), the mechanism for how PAS domain mutations disrupt hERG function when expressed in more physiological conditions remains unclear.Previously, we showed that slow deactivation could be restored in LQT2 mutant hERG R56Q channels by application of a genetically encoded PAS domain (NPAS) in Xenopus oocytes (15). Here, we sought to determine whether NPAS was a general mechanism for rescue of LQT2 mutant channels. To carry out this goal we investigated 1) whether 11 different hERG PAS-LQT2 mutations that were gating deficient in Xenopus oocytes resulted in a loss-of-function in a human heterologous expression system and 2) whether NPAS could restore gating in several different hERG PAS-LQT2 mutant channels with gating defects in a mammalian system. We found that the 11 hERG PAS-LQT2 channels exhibited a spectrum of deficiencies in mammalian cells, and only channels with mutations located on one face of the PAS domain were gating deficient. These mutant channels exhibited an array of gating defects, including faster deactivation kinetics and a right-shift in the steady-state inactivation relationship, the combination of which resulted in aberrant currents in response to a dynamic ramp clamp. We found that NPAS rescued gating defects in hERG PAS-LQT2 channels by inducing slower deactivation kinetics and a left-shift in the steady-state inactivation relationship, which restored wild-type-like currents during the dynamic ramp clamp. Thus, NPAS restored function to channels that had a variety of gating defects. Therefore, in this study,

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Section: Discussioncontrasting

confidence: 56%

Rescue of Aberrant Gating by a Genetically Encoded PAS (Per-Arnt-Sim) Domain in Several Long QT Syndrome Mutant Human Ether-á-go-go-related Gene Potassium Channels

Gianulis

Trudeau

2011

Journal of Biological Chemistry

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“…Is this a unique feature of CNBD or will other highly structured domains have similar effects? It has been recently shown that a mutation in the PAS domain causes ER retention (Paulussen et al, 2002). However, it has also been reported that other mutations in the PAS domain or N-terminal truncations that eliminate this domain do not always preclude generation of functional HERG channels (Morais Cabral et al, 1998;Chen et al, 1999;Wang et al, 1998;Viloria et al, 2000;Gomez-Varela et al, 2002).…”

Section: Discussionmentioning

confidence: 99%

Identification of the cyclic-nucleotide-binding domain as a conserved determinant of ion-channel cell-surface localization

Akhavan

Atanasiu

Noguchi

et al. 2005

Journal of Cell Science

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Mutations of a putative cyclic-nucleotide-binding domain (CNBD) can disrupt the function of the hyperpolarization-activated cyclic-nucleotide-gated channel (HCN2) and the human ether-a-go-go-related gene potassium channel (HERG). Loss of function caused by C-terminal truncation, which includes all or part of the CNBD in HCN and HERG, has been related to abnormal channel trafficking. Similar defects have been reported for several of the missense mutations of HERG associated with long QT syndrome type 2 (LQT2). Thus, we postulate that normal processing of these channels depends upon the presence of the CNBD. Here, we show that removal of the entire CNBD prevents Golgi transit, surface localization and function of HERG channel tetramers. This is also true when any of the structural motifs of the CNBD is deleted, suggesting that deletion of any highly conserved region along the entire length of the CNBD can disrupt channel trafficking. Furthermore, we demonstrate that defective trafficking is a consequence of all LQT2 mutations in the CNBD, including two mutations not previously assessed and two others for which there are conflicting results in the literature. The trafficking sensitivity of the CNBD might be of general significance for other ion channels because complete deletion of the CNBD or mutations at highly conserved residues within the CNBD of the related ERG3 channel and HCN2 also prevent Golgi transit. These results broadly implicate the CNBD in ion-channel trafficking that accounts for the commonly observed loss of function associated with CNBD mutants and provides a rationale for distinct genetic disorders.

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“…WT-hERG mainly labelled at the surface membrane ( Figure 2A); in contrast, the trafficking-defective G572R-hERG was mainly expressed in the cytoplasm ( Figure 2C) (20,21). Figure 2B shows that G572R-hERG/WT-hERG results in less plasma membrane fluorescence compared with the consequences of WT-hERG.…”

Section: Western Blotting and Immunocytochemistry Analysesmentioning

confidence: 99%

Novel characteristics of a trafficking-defective G572R-hERG channel linked to hereditary long QT syndrome

Lian

Huang

Zhou

et al. 2010

Canadian Journal of Cardiology

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A Novel Mutation (T65P) in the PAS Domain of the Human Potassium Channel HERG Results in the Long QT Syndrome by Trafficking Deficiency

Cited by 89 publications

References 40 publications

Rescue of Aberrant Gating by a Genetically Encoded PAS (Per-Arnt-Sim) Domain in Several Long QT Syndrome Mutant Human Ether-á-go-go-related Gene Potassium Channels

Rescue of Aberrant Gating by a Genetically Encoded PAS (Per-Arnt-Sim) Domain in Several Long QT Syndrome Mutant Human Ether-á-go-go-related Gene Potassium Channels

Identification of the cyclic-nucleotide-binding domain as a conserved determinant of ion-channel cell-surface localization

Novel characteristics of a trafficking-defective G572R-hERG channel linked to hereditary long QT syndrome

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