Sa12b Peptide from Solitary Wasp Inhibits ASIC Currents in Rat Dorsal Root Ganglion Neurons.

Hernández Hernández,Soto Soto,Salceda Salceda,Vega Vega,Konno Konno,Zaharenko Zaharenko

doi:10.3390/toxins11100585

Abstract

In this work, we evaluate the effect of two peptides Sa12b (EDVDHVFLRF) and Sh5b (DVDHVFLRF-NH2) on Acid-Sensing Ion Channels (ASIC). These peptides were purified from the venom of solitary wasps Sphex argentatus argentatus and Isodontia harmandi, respectively. Voltage clamp recordings of ASIC currents were performed in whole cell configuration in primary culture of dorsal root ganglion (DRG) neurons from (P7-P10) CII Long-Evans rats. The peptides were applied by preincubation for 25 s (20 s in pH 7.4 solution and 5 s in pH 6.1 solution) or by co-application (5 s in pH 6.1 solution). Sa12b inhibits ASIC current with an IC50 of 81 nM, in a concentration-dependent manner when preincubation application was used. While Sh5b did not show consistent results having both excitatory and inhibitory effects on the maximum ASIC currents, its complex effect suggests that it presents a selective action on some ASIC subunits. Despite the similarity in their sequences, the action of these peptides differs significantly. Sa12b is the first discovered wasp peptide with a significant ASIC inhibitory effect.

Highlights

Acid-sensing ion channels (ASICs) are proton-gated Na+ channels of the ENaC/Degenerin channel family characterized by their sodium permeability, sensitivity to amiloride, and voltage insensitivity [1,2,3,4]
Stable proton-gated currents were recorded from 123 dorsal root ganglion (DRG) neurons obtained from 32 rats
ASIC currents from isolated DRG neurons showed diverse characteristics, which result from the expression of ASIC heteromers and homomers of ASIC1–4 subunits in these neurons

Summary

Introduction

Acid-sensing ion channels (ASICs) are proton-gated Na+ channels of the ENaC/Degenerin channel family characterized by their sodium permeability, sensitivity to amiloride, and voltage insensitivity [1,2,3,4]. ASICs are widely distributed in the central and peripheral nervous systems, as well as in sensory and non-neuronal tissue [5]. Most functions of these channels have been described using inhibitors of ASIC channels combined with the use of knockout or knockdown animals [6]. RFa-related peptides share with FMRFa the characteristic C-terminus motive Arg-Phe-NH2 [10]. These neuropeptides are direct activators of two ion channels of the ENaC/Deg superfamily: the invertebrate FMRFa-gated Na+ channel (FaNaC) and the Hydra-RFa-gated Na+ channels (HyNaC) [11]

Methods

Results

Conclusion