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

 

Manyi Yang1 , Yubin Li2 , Longfei Liu3 , Maojun Zhou2

 

1 Department of Hepatobiliary and Pancreatic Surgery, NHC Key Laboratory of Nanobiological Technology, Xiangya Hospital, Central South University, Changsha, Hunan, China.

2 Department of Oncology, State Local Joint Engineering Laboratory for Anticancer Drugs, NHC Key Laboratory of Cancer Proteomics, Xiangya Hospital, Central South University, Changsha, Hunan, China.

3 Department of Urology, National Clinical Research Center for Geriatric Disorder, Xiangya Hospital, Central South University, Changsha, Hunan, China.

 

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 Cav 1.2 and Cav 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 IC50 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 Cav 1.2 currents and 12.86% ± 4.93% of the human Cav 2.2 currents.

 

Conclusions: Vr3a can simultaneously affect sodium, potassium and calcium currents. This novel triple-target conotoxin Vr3a expands understanding of conotoxin functions.

 

Keywords: Conotoxin Conopeptide Sodium currents Potassium currents Calcium currents

 

Correspondence: zhoumaojun@csu.edu.cn

 

Received: 10 November 2020; Accepted: 01 March 2021; Published online: 11 June 2021.