Mechanisms of noncovalent β subunit regulation of NaV channel gating

Zhu, Wandi; Voelker, Taylor L.; Varga, Zoltán; Schubert, A.; Nerbonne, Jeanne M.; Silva, Jonathan R.

doi:10.1085/jgp.201711802

Cited by 66 publications

(138 citation statements)

References 63 publications

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“…A similarly selective electrophysiological effect of β3 on Nav1.5 inactivation has been reported when studied in Xenopus oocytes . It is also consistent with data from the Scn3b −/− mouse model that lacks β3 expression and shows distinctive conduction abnormalities .…”

Section: Discussionsupporting

confidence: 87%

“…A similarly selective electrophysiological effect of β3 on Nav1.5 inactivation has been reported when studied in Xenopus oocytes. 4,41 It is also consistent with data from the Scn3b −/− mouse model that lacks β3 expression and shows distinctive conduction abnormalities. 7,8 Thus, the electrophysiological effects described here mimic key features of the channel behavior in a whole animal model.…”

Section: Discussionsupporting

confidence: 86%

“…However, AFM images indicate that under conditions of high expression, the β3-subunit can bind at up to four separate sites symmetrically arranged around the Nav1.5 α-subunit, 10 a finding that is consistent with recent electrophysiological work that indicated more than one binding site for β3 on the Nav1.5 α-subunit. 41 The presence of multiple β-subunits around the α-subunit is likely to increase the effective "footprint" of a Nav1.5 complex and could provide a simple explanation for the increased radii distribution shown in Figure 2D.…”

Section: Discussionmentioning

confidence: 97%

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Supramolecular clustering of the cardiac sodium channel Nav1.5 in HEK293F cells, with and without the auxiliary β3‐subunit

et al. 2020

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Voltage‐gated sodium channels comprise an ion‐selective α‐subunit and one or more associated β‐subunits. The β3‐subunit (encoded by the SCN3B gene) is an important physiological regulator of the heart‐specific sodium channel, Nav1.5. We have previously shown that when expressed alone in HEK293F cells, the full‐length β3‐subunit forms trimers in the plasma membrane. We extend this result with biochemical assays and use the proximity ligation assay (PLA) to identify oligomeric β3‐subunits, not just at the plasma membrane, but throughout the secretory pathway. We then investigate the corresponding clustering properties of the α‐subunit and the effects upon these of the β3‐subunits. The oligomeric status of the Nav1.5 α‐subunit in vivo, with or without the β3‐subunit, has not been previously investigated. Using super‐resolution fluorescence imaging, we show that under conditions typically used in electrophysiological studies, the Nav1.5 α‐subunit assembles on the plasma membrane of HEK293F cells into spatially localized clusters rather than individual and randomly dispersed molecules. Quantitative analysis indicates that the β3‐subunit is not required for this clustering but β3 does significantly change the distribution of cluster sizes and nearest‐neighbor distances between Nav1.5 α‐subunits. However, when assayed by PLA, the β3‐subunit increases the number of PLA‐positive signals generated by anti‐(Nav1.5 α‐subunit) antibodies, mainly at the plasma membrane. Since PLA can be sensitive to the orientation of proteins within a cluster, we suggest that the β3‐subunit introduces a significant change in the relative alignment of individual Nav1.5 α‐subunits, but the clustering itself depends on other factors. We also show that these structural and higher‐order changes induced by the β3‐subunit do not alter the degree of electrophysiological gating cooperativity between Nav1.5 α‐subunits. Our data provide new insights into the role of the β3‐subunit and the supramolecular organization of sodium channels, in an important model cell system that is widely used to study Nav channel behavior.

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Section: Discussionsupporting

confidence: 87%

Section: Discussionsupporting

confidence: 86%

Section: Discussionmentioning

confidence: 97%

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Supramolecular clustering of the cardiac sodium channel Nav1.5 in HEK293F cells, with and without the auxiliary β3‐subunit

et al. 2020

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“…E, time constants of fast inactivation revealed by single exponential fit of inactivating current traces as shown in Fig. 2C recent studies using voltage-clamp fluorometry show that, at least in Nav1.5, the voltage-sensing domain of DIV is involved in β1 interaction as well (Zhu et al 2017). Zimmer et al have shown that different parts of β1 are necessary for interaction with Nav1.5 compared to Nav1.2 (Zimmer & Benndorf, 2002).…”

Section: Discussionmentioning

confidence: 90%

“…In addition, recent studies using voltage‐clamp fluorometry show that, at least in Nav1.5, the voltage‐sensing domain of DIV is involved in β1 interaction as well (Zhu et al . ). Zimmer et al .…”

Section: Discussionmentioning

confidence: 97%

β1 subunit stabilises sodium channel Nav1.7 against mechanical stress

Körner

Meents

Machtens

et al. 2018

The Journal of Physiology

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Voltage-gated sodium channels are key players in neuronal excitability and pain signalling. Precise gating of these channels is crucial as even small functional alterations can lead to pathological phenotypes such as pain or heart failure. Mechanical stress has been shown to affect sodium channel activation and inactivation. This suggests that stabilising components are necessary to ensure precise channel gating in living organisms. Here, we show that mechanical shear stress affects voltage dependence of activation and fast inactivation of the Nav1.7 channel. Co-expression of the β1 subunit, however, protects both gating modes of Nav1.7 against mechanical shear stress. Using molecular dynamics simulation, homology modelling and site-directed mutagenesis, we identify an intramolecular disulfide bond of β1 (Cys21-Cys43) which is partially involved in this process: the β1-C43A mutant prevents mechanical modulation of voltage dependence of activation, but not of fast inactivation. Our data emphasise the unique role of segment 6 of domain IV for sodium channel fast inactivation and confirm previous reports that the intracellular process of fast inactivation can be modified by interfering with the extracellular end of segment 6 of domain IV. Thus, our data suggest that physiological gating of Nav1.7 may be protected against mechanical stress in a living organism by assembly with the β1 subunit.

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Mechanisms of Drug Binding to Voltage-Gated Sodium Channels

O’Leary

Chahine

2017

Handbook of Experimental Pharmacology

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Voltage-gated sodium (Na) channels are expressed in virtually all electrically excitable tissues and are essential for muscle contraction and the conduction of impulses within the peripheral and central nervous systems. Genetic disorders that disrupt the function of these channels produce an array of Na channelopathies resulting in neuronal impairment, chronic pain, neuromuscular pathologies, and cardiac arrhythmias. Because of their importance to the conduction of electrical signals, Na channels are the target of a wide variety of local anesthetic, antiarrhythmic, anticonvulsant, and antidepressant drugs. The voltage-gated family of Na channels is composed of α-subunits that encode for the voltage sensor domains and the Na-selective permeation pore. In vivo, Na channel α-subunits are associated with one or more accessory β-subunits (β-β) that regulate gating properties, trafficking, and cell-surface expression of the channels. The permeation pore of Na channels is divided in two parts: the outer mouth of the pore is the site of the ion selectivity filter, while the inner cytoplasmic pore serves as the channel activation gate. The cytoplasmic lining of the permeation pore is formed by the S6 segments that include highly conserved aromatic amino acids important for drug binding. These residues are believed to undergo voltage-dependent conformational changes that alter drug binding as the channels cycle through the closed, open, and inactivated states. The purpose of this chapter is to broadly review the mechanisms of Na channel gating and the models used to describe drug binding and Na channel inhibition.

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Mechanisms of noncovalent β subunit regulation of NaV channel gating

Cited by 66 publications

References 63 publications

Supramolecular clustering of the cardiac sodium channel Nav1.5 in HEK293F cells, with and without the auxiliary β3‐subunit

Supramolecular clustering of the cardiac sodium channel Nav1.5 in HEK293F cells, with and without the auxiliary β3‐subunit

β1 subunit stabilises sodium channel Nav1.7 against mechanical stress

Mechanisms of Drug Binding to Voltage-Gated Sodium Channels

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