Molecular basis for class Ib anti-arrhythmic inhibition of cardiac sodium channels

Pless, Stephan A.; Galpin, Jason D.; Frankel, Adam; Ahern, Christopher A.

doi:10.1038/ncomms1351

Cited by 88 publications

(86 citation statements)

References 56 publications

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“…However, our assay condition was tuned to set up membrane voltages that can minimize the influence from these differences. In the SoCal fluorescent assay, consistent with the literature (Pless et al, 2011), class Ib antiarrhythmics (such as lidocaine) has more than 10-fold change in IC 50 values by F1760A mutation, whereas class Ia and Ic antiarrhythmics (such as flecainide, quinidine, and propafenone) only show five-to sevenfold change (Supplemental Fig. 4B).…”

Section: Discussionsupporting

confidence: 74%

“…For instance, the number of drug binding sites in Nav channels is still controversial (Mike and Lukacs, 2010). Furthermore, the most well recognized residue for drug binding, F1760 in Nav1.5, was reported to be more important for an inhibitory effect of class Ib antiarrhythmics but not as important for class Ia and Ic antiarrhythmics (Pless et al, 2011). Therefore, it would be of great interest to systemically evaluate the promiscuity of Nav channels and examine the site dependence using structurally diverse libraries in a high-throughput manner.…”

Section: Introductionmentioning

confidence: 99%

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Reporting Sodium Channel Activity Using Calcium Flux: Pharmacological Promiscuity of Cardiac Nav1.5

Zhang

Zou

et al. 2014

Mol Pharmacol

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Voltage-gated sodium (Nav) channels are essential for membrane excitability and represent therapeutic targets for treating human diseases. Recent reports suggest that these channels, e.g., Nav1.3 and Nav1.5, are inhibited by multiple structurally distinctive small molecule drugs. These studies give reason to wonder whether these drugs collectively target a single site or multiple sites in manifesting such pharmacological promiscuity. We thus investigate the pharmacological profile of Nav1.5 through systemic analysis of its sensitivity to diverse compound collections. Here, we report a dual-color fluorescent method that exploits a customized Nav1.5 [calcium permeable Nav channel, subtype 5 (SoCal5)] with engineered-enhanced calcium permeability. SoCal5 retains wildtype (WT) Nav1.5 pharmacological profiles. WT SoCal5 and SoCal5 with the local anesthetics binding site mutated (F1760A) could be expressed in separate cells, each with a differentcolored genetically encoded calcium sensor, which allows a simultaneous report of compound activity and site dependence. The pharmacological profile of SoCal5 reveals a hit rate (.50% inhibition) of around 13% at 10 mM, comparable to that of hERG. The channel activity is susceptible to blockage by known drugs and structurally diverse compounds. The broad inhibition profile is highly dependent on the F1760 residue in the inner cavity, which is a residue conserved among all nine subtypes of Nav channels. Both promiscuity and dependence on F1760 seen in Nav1.5 were replicated in Nav1.4. Our evidence of a broad inhibition profile of Nav channels suggests a need to consider off-target effects on Nav channels. The site-dependent promiscuity forms a foundation to better understand Nav channels and compound interactions.

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Section: Discussionsupporting

confidence: 74%

Section: Introductionmentioning

confidence: 99%

Reporting Sodium Channel Activity Using Calcium Flux: Pharmacological Promiscuity of Cardiac Nav1.5

Zhang

Zou

et al. 2014

Mol Pharmacol

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“…Mutation of this residue to a nonaromatic alanine dramatically altered TEA inhibition but did not abolish it completely (wild-type: 14% versus F649A: 35% of current remaining at 300 M TEA). However, because of the apparent intolerance of the TRPV1 channels at the Phe649 site to the in vivo nonsense suppression method, required for the expression of fluorinated phenylalanine residues, we were unable to directly test for a possible cationinteraction between Phe649 and TEA (data not shown), similar to that demonstrated between lidocaine and a conserved phenylalanine residue in sodium channels (Ahern et al, 2008;Pless et al, 2011). Next, we turned our attention to Glu648, the residue that aligns directly with Thr449 in Shaker and has also been shown to be critical for protonevoked TRP channel activation without affecting heat or capsaicin sensitivity (Jordt et al, 2000).…”

Section: Extracellular Quaternary Ammonium Block Of Trpv1mentioning

confidence: 97%

Extracellular Quaternary Ammonium Blockade of Transient Receptor Potential Vanilloid Subtype 1 Channels Expressed in Xenopus laevis Oocytes

et al. 2012

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Transient receptor potential vanilloid subtype 1 (TRPV1) channels are essential nociceptive integrators in primary afferent neurons. These nonselective cation channels are inhibited by local anesthetic compounds through an undefined mechanism. Here, we show that lidocaine inhibits TRPV1 channels expressed in Xenopus laevis oocytes, whereas the neutral local anesthetic, benzocaine, does not, suggesting that a titratable amine is required for high-affinity inhibition. Consistent with this possibility, extracellular tetraethylammonium (TEA) and tetramethylammonium application produces potent, voltage-dependent pore block. Alanine substitutions at Phe649 and Glu648, residues in the putative TRPV1 pore region, significantly abrogated the concentration-dependent TEA inhibition. The results suggest that large cations, shown previously to enter cells through activated transient receptor potential channels, can also act as channel blockers.

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“…Surprisingly, tetracaine is predicted to bind in a pose that lies horizontally across the central cavity, with its positively charged ammonium group in the center of the cavity near the focus of the partially negatively charged ends of the four P helices and its aromatic group in the crevice between domains III and IV (Bruhova et al, 2008). In this position, the aromatic group makes p-p interactions with the highly conserved Phe residue, which was previously implicated in drug binding by site-directed mutagenesis with substitutions of natural and unnatural amino acid residues (Ragsdale et al, 1994;Pless et al, 2011). Further structural work with bacterial and mammalian Na V channels with bound drugs should give a more detailed picture of this important drug-receptor interaction.…”

Section: Drug Receptor Sites In Sodium Channelsmentioning

confidence: 99%

Structural Basis for Pharmacology of Voltage-Gated Sodium and Calcium Channels

2015

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Voltage-gated sodium channels initiate action potentials in nerve, muscle, and other electrically excitable cells. Voltage-gated calcium channels are activated by depolarization during action potentials, and calcium influx through them is the key second messenger of electrical signaling, initiating secretion, contraction, neurotransmission, gene transcription, and many other intracellular processes. Drugs that block sodium channels are used in local anesthesia and the treatment of epilepsy, bipolar disorder, chronic pain, and cardiac arrhythmia. Drugs that block calcium channels are used in the treatment of epilepsy, chronic pain, and cardiovascular disorders, including hypertension, angina pectoris, and cardiac arrhythmia. The principal pore-forming subunits of voltage-gated sodium and calcium channels are structurally related and likely to have evolved from ancestral voltage-gated sodium channels that are widely expressed in prokaryotes. Determination of the structure of a bacterial ancestor of voltage-gated sodium and calcium channels at high resolution now provides a three-dimensional view of the binding sites for drugs acting on sodium and calcium channels. In this minireview, we outline the different classes of sodium and calcium channel drugs, review studies that have identified amino acid residues that are required for their binding and therapeutic actions, and illustrate how the analogs of those key amino acid residues may form drug-binding sites in threedimensional models derived from bacterial channels.

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Molecular basis for class Ib anti-arrhythmic inhibition of cardiac sodium channels

Cited by 88 publications

References 56 publications

Reporting Sodium Channel Activity Using Calcium Flux: Pharmacological Promiscuity of Cardiac Nav1.5

Reporting Sodium Channel Activity Using Calcium Flux: Pharmacological Promiscuity of Cardiac Nav1.5

Extracellular Quaternary Ammonium Blockade of Transient Receptor Potential Vanilloid Subtype 1 Channels Expressed in Xenopus laevis Oocytes

Structural Basis for Pharmacology of Voltage-Gated Sodium and Calcium Channels

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