A novel proline-rich M-superfamily conotoxin that can simultaneously affect sodium, potassium and calcium currents

Abstract

Background Conotoxins have become a research hotspot in the neuropharmacology field for their high activity and specificity in targeting ion channels and neurotransmitter receptors. There have been reports of a conotoxin acting on two ion channels, but rare reports of a conotoxin acting on three ion channels. Methods Vr3a, a proline-rich M-superfamily conotoxin from a worm-hunting Conus varius , was obtained by solid-phase synthesis and identified by mass spectrometry. The effects of synthesized Vr3a on sodium, potassium and calcium currents were tested on rat DRG cells by patch clamp experiments. The further effects of Vr3a on human Ca v 1.2 and Ca v 2.2 currents were tested on HEK293 cells. Results About 10 μM Vr3a has no effects on the peak sodium currents, but can induce a ~10 mV shift in a polarizing direction in the current-voltage relationship. In addition, 10 μM Vr3a can increase 19.61 ± 5.12% of the peak potassium currents and do not induce a shift in the current-voltage relationship. An amount of 10 μM Vr3a can inhibit 31.26% ± 4.53% of the peak calcium currents and do not induce a shift in the current-voltage relationship. The IC 50 value of Vr3a on calcium channel currents in rat DRG neurons is 19.28 ± 4.32 μM. Moreover, 10 μM Vr3a can inhibit 15.32% ± 5.41% of the human Ca v 1.2 currents and 12.86% ± 4.93% of the human Ca v 2.2 currents. Conclusions Vr3a can simultaneously affect sodium, potassium and calcium currents. This novel triple-target conotoxin Vr3a expands understanding of conotoxin functions.

Conotoxins Targeting Voltage-Gated Sodium Ion Channels

“…Some conotoxins, such as Vr3a and SIIID, have attracted attention because of their unique targeting or structural characteristics. Vr3a is reported to act on Na V , Ca V, and K V channels (Yang et al, 2021). It has no obvious sequence homology with other conotoxins of the M-superfamily and does not affect peak sodium currents of Na V channels in rat DRG neurons, but was found to shift the I-V relationship by ~10 mV in a polarizing direction at a concentration of 10 μM (Yang et al, 2021).…”

High-Throughput Prediction and Design of Novel Conopeptides for Biomedical Research and Development

“…According to the arrangement of cysteine frameworks, every superfamily can be subdivided into several families. For example, Asuperfamily conopeptides, with four representative cysteine frameworks (namely, I, II, IV, and XIV; Figure 1), are therefore subdivided into α, αA, and κA families; M-superfamily conopeptides, with five cysteine frameworks of II, XIV, III, VI, and VII, are further subdivided into μ and ψ families; O-superfamily conopeptides have four cysteine frameworks (XII, XV, VI, and VII) and are subsequently divided into δ, μO, ω, κ, and γ families [40][41][42][43]. The high diversity of cone snails and their conopeptides, with an outline of the 29 major conopeptide superfamilies [19,21,37,44], are summarized in Figure 1 for convenient comparison.…”

O1-conotoxin Tx6.7 cloned from the genomic DNA of Conus textile that inhibits calcium currents

“…Each Conus species may contain up to 1000 conotoxins, which makes the library of bioactive conotoxin peptides very large [4,5], perhaps over 140,000 different peptides in total. Conotoxins act potently and selectively on a lot of membrane receptors and ion channels, thus showing great potential as neuropharmacology tools and therapeutic candidates, and one calcium channel inhibitor, ω-conotoxin MVIIA (Prialt TM ), was developed as a drug for treating neuropathic pain [6][7][8].…”