Peptide Toxin Inhibition of Voltage Gated Calcium Channels

McDonough, Stefan I.

doi:10.1007/978-1-4419-9254-3_4

Cited by 7 publications

(11 citation statements)

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“…The toxin was included in the pipette so as to avoid uncertainty about the toxin concentration at the channels of interest that can arise during bath administration as a result of nonspecific binding of peptide toxins to the perfusion system and the slice (McDonough, 2004;Tringham et al, 2007). As described previously (Tringham et al, 2007), currents were evoked with depolarizing voltage ramps (Fig.…”

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confidence: 99%

“…One characteristic by which N-type channels in neurons have been identified and by which recombinant channels containing a Ca V 2.2 subunit have been matched to native N-type channels, is the irreversible inhibition of Ca 2ϩ or Ba 2ϩ currents by -conotoxin (CTx) GVIA (McDonough, 2004;McGivern, 2006). The property used to identify native P-type channels and recombinant channels containing a Ca V 2.1 subunit has been the irreversible inhibition of currents by -agatoxin (Aga) IVA (McDonough, 2004;McGivern, 2006).…”

Section: Introductionmentioning

confidence: 99%

“…The use of toxins originating from venoms of assorted species has aided the classification of Ca 2ϩ channels as T-, N-, L-, P-, Q-, or R-type and helped elucidate the diverse physiological roles of the different Ca 2ϩ channel classes (McDonough, 2004;McGivern, 2006). It has also helped implicate altered function of distinct types of Ca 2ϩ channels in specific pathophysiological conditions and led to the development of an -conotoxin as an N-type channel blocker that is used in the management of intractable pain (Snutch, 2005;McGivern, 2006).One characteristic by which N-type channels in neurons have been identified and by which recombinant channels containing a Ca V 2.2 subunit have been matched to native N-type channels, is the irreversible inhibition of Ca 2ϩ or Ba 2ϩ currents by -conotoxin (CTx) GVIA (McDonough, 2004;McGivern, 2006). The property used to identify native P-type channels and recombinant channels containing a Ca V 2.1 subunit has been the irreversible inhibition of currents by -agatoxin (Aga) IVA (McDonough, 2004;McGivern, 2006).…”

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“…The property used to identify native P-type channels and recombinant channels containing a Ca V 2.1 subunit has been the irreversible inhibition of currents by -agatoxin (Aga) IVA (McDonough, 2004;McGivern, 2006). The selectivity of -Aga-IVA for P-type over N-type channels is not absolute; at concentrations higher than those necessary to block P-type currents, -Aga-IVA also blocks N-type currents (Sidach and Mintz, 2000).…”

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Protease Treatment of Cerebellar Purkinje Cells Renders ω-Agatoxin IVA-Sensitive Ca²⁺ Channels Insensitive to Inhibition by ω-Conotoxin GVIA

Tringham

Dupere²,

Payne³

et al. 2007

J Pharmacol Exp Ther

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The identification of currents carried by N-and P-type Ca 2ϩ channels in the nervous system relies on the use of -conotoxin (CTx) GVIA and -agatoxin (Aga) IVA. The peptide -Aga-IVA inhibits P-type currents at nanomolar concentrations and N-type currents at micromolar concentrations. -CTx-GVIA blocks N-type currents, but there have been no reports that it can also inhibit P-type currents. To assess the effects of -CTx-GVIA on P-type channels, we made patch-clamp recordings from the soma of Purkinje cells in cerebellar slices of mature [postnatal days (P) 40 -50, P40 -50] and immature (P13-20) rats, in which P-type channels carry most of the Ca 2ϩ channel current (Ն85%). These showed that micromolar concentrations of -CTx-GVIA inhibited the current in P40 -50 cells (66%, 3 M; 78%, 10 M) and in P13-20 Purkinje cells (86%, 3 M; 89%, 10 M). The inhibition appeared to be reversible, in contrast to the known irreversible inhibition of N-type current. Exposure of slices from young animals to the enzyme commonly used to dissociate Purkinje cells, protease XXIII, abolished the inhibition by -CTx-GVIA but not by -Aga-IVA (84%, 30 nM). Our finding that micromolar concentrations of -CTx-GVIA inhibit P-type currents suggests that specific block of N-type current requires the use of submicromolar concentrations. The protease-induced removal of block by -CTx-GVIA but not by -Aga-IVA indicates a selective proteolytic action at site(s) on P-type channels with which -CTx-GVIA interacts. It also suggests that Ca 2ϩ channel pharmacology in neurons dissociated using protease may not predict that in neurons not exposed to the enzyme.Voltage-gated Ca 2ϩ channels control numerous cellular functions, including neuronal electrical activity, gene expression, and intracellular signaling. The use of toxins originating from venoms of assorted species has aided the classification of Ca 2ϩ channels as T-, N-, L-, P-, Q-, or R-type and helped elucidate the diverse physiological roles of the different Ca 2ϩ channel classes (McDonough, 2004;McGivern, 2006). It has also helped implicate altered function of distinct types of Ca 2ϩ channels in specific pathophysiological conditions and led to the development of an -conotoxin as an N-type channel blocker that is used in the management of intractable pain (Snutch, 2005;McGivern, 2006).One characteristic by which N-type channels in neurons have been identified and by which recombinant channels containing a Ca V 2.2 subunit have been matched to native N-type channels, is the irreversible inhibition of Ca 2ϩ or Ba 2ϩ currents by -conotoxin (CTx) GVIA (McDonough, 2004;McGivern, 2006). The property used to identify native P-type channels and recombinant channels containing a Ca V 2.1 subunit has been the irreversible inhibition of currents by -agatoxin (Aga) IVA (McDonough, 2004;McGivern, 2006). The selectivity of -Aga-IVA for P-type over N-type channels is not absolute; at concentrations higher than those necessary to block P-type currents, -Aga-IVA also blocks N-type currents (Sidach and Mintz, 20...

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Section: Introductionmentioning

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Protease Treatment of Cerebellar Purkinje Cells Renders ω-Agatoxin IVA-Sensitive Ca²⁺ Channels Insensitive to Inhibition by ω-Conotoxin GVIA

Tringham

Dupere²,

Payne³

et al. 2007

J Pharmacol Exp Ther

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Using Pharmabase to Perform Pharmacological Analyses of Cell Function

Smith

Remsen

2006

CP in Bioinformatics

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In this post-genomic period of biological research, the emphasis in cell biology is returning to an understanding of cell function and dynamics, particularly with regard to protein composition and function. New technologies abound, offering methods to examine protein-dependent processes in living systems, frequently in real time. Experimentally, one popular tool for defining and manipulating such activities is the use of pharmacological compounds to alter the performance of proteins within the living cell. However, using these compounds can be a daunting process, particularly to the uninitiated. Locating the correct compound, understanding its target specificity, and even knowing how to handle and prepare it for use, are frequently in the domain of the specialist. Pharmabase sets out to overcome these barriers by providing simple protocols, guiding the user through a series of choices, to a database of compound records addressing the points above.Pharmabase is a database containing detailed information on the physicochemical properties of ∼1000 pharmacologically active small molecules and compounds. The compound data are linked to the target molecules, frequently proteins, organized to display their function within a cell. For example, the database is organized so that the user can navigate to known interactions between these small molecules and their receptors within the biological system of membrane transport. This unit describes how to search and access the information in Pharmabase. The different search routes presented are based broadly on subject and/or graphic navigation. Getting started with Pharmabase and performing simple searches via subject or compound is described in Basic Protocol 1. The main way to search Pharmabase is via Membrane Transport (Basic Protocol 2). This subject navigator allows the investigator to access compounds targeting membrane transporters of ions and molecules. Transporters, in the context of this database, encompass channels, pumps, and porters (symporters, uniporters, and antiporters). (Further material on the diversity of these mechanisms and links to gene sites can be found at http://www.tcdb.org and the role of these molecules in disease can be accessed through http://www.channelopathies.org.; also see Rose and Griggs, 2001.) Four other subject-based navigators, derived by subset organization, are described in Basic Protocol 3. These are: Metabolism, Intracellular Messengers, Cell Signaling, and Cell Area. The compound database is sorted according to these subsets and their constitutive components. These secondary navigation routes are in place to provide a cross-referencing structure to other indexing methods and all share the purpose of reducing the database to a smaller subset of compounds and targets, tailored to the user's interest. (These navigators will be further expanded and and additional search routines based around Diseases and Tissues, as well as Action Terms, e.g., "ionophore" or "reporter" are under construction). Basic Protocol 4 describes the most recent ...

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Calcium ion channels: challenges and successes in drug discovery

McDonough

2012

WIREs Membr Transp Signal

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There are both opportunities and challenges in developing improved or novel therapeutics based on targeting voltage-gated calcium channels. Calcium channels are technically difficult with respect to target-based drug discovery but unquestionably are key points for influencing human physiology and pathophysiology. Many marketed drugs, including nifedipine, nimodipine, ethosuximide, pregabalin, and ziconotide, exert therapeutic efficacy via inhibition of calcium channels. Although there is no obvious path to improving these existing drugs, recent clinical results with dihydropyridine drugs point to testable strategies for treatment of Parkinson's disease and possibly other CNS disorders by inhibiting L-type calcium channels. Roles of T-type calcium channels in pain and in abnormal sleep are plausible and may soon be tested with clinical trials of novel therapeutics. Success with any of these trials certainly will be followed by intensive efforts for further refinements around the target class.

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Peptide Toxin Inhibition of Voltage Gated Calcium Channels

Cited by 7 publications

References 259 publications

Protease Treatment of Cerebellar Purkinje Cells Renders ω-Agatoxin IVA-Sensitive Ca²⁺ Channels Insensitive to Inhibition by ω-Conotoxin GVIA

Protease Treatment of Cerebellar Purkinje Cells Renders ω-Agatoxin IVA-Sensitive Ca²⁺ Channels Insensitive to Inhibition by ω-Conotoxin GVIA

Using Pharmabase to Perform Pharmacological Analyses of Cell Function

Calcium ion channels: challenges and successes in drug discovery

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Peptide Toxin Inhibition of Voltage Gated Calcium Channels

Cited by 7 publications

References 259 publications

Protease Treatment of Cerebellar Purkinje Cells Renders ω-Agatoxin IVA-Sensitive Ca2+ Channels Insensitive to Inhibition by ω-Conotoxin GVIA

Protease Treatment of Cerebellar Purkinje Cells Renders ω-Agatoxin IVA-Sensitive Ca2+ Channels Insensitive to Inhibition by ω-Conotoxin GVIA

Using Pharmabase to Perform Pharmacological Analyses of Cell Function

Calcium ion channels: challenges and successes in drug discovery

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Product

Resources

About

Protease Treatment of Cerebellar Purkinje Cells Renders ω-Agatoxin IVA-Sensitive Ca²⁺ Channels Insensitive to Inhibition by ω-Conotoxin GVIA

Protease Treatment of Cerebellar Purkinje Cells Renders ω-Agatoxin IVA-Sensitive Ca²⁺ Channels Insensitive to Inhibition by ω-Conotoxin GVIA