Identification of IQM-266, a Novel DREAM Ligand That Modulates KV4 Currents.

Diego A Peraza,José R Naranjo,Alejandro López-Hurtado,Pablo Miaja,Antonio R Artalejo,Marta Gutiérrez-Rodríguez,Mercedes Martín-Martínez,Laura Lagartera,Carmen Valenzuela,Paula G Socuéllamos,Pilar Cercós,Yaiza G Merinero,Sara A Sánchez,Luis A Olivos-Oré,Carolina Izquierdo García

doi:10.3389/fnmol.2019.00011

Abstract

Downstream Regulatory Element Antagonist Modulator (DREAM)/KChIP3/calsenilin is a neuronal calcium sensor (NCS) with multiple functions, including the regulation of A-type outward potassium currents (IA). This effect is mediated by the interaction between DREAM and KV4 potassium channels and it has been shown that small molecules that bind to DREAM modify channel function. A-type outward potassium current (IA) is responsible of the fast repolarization of neuron action potentials and frequency of firing. Using surface plasmon resonance (SPR) assays and electrophysiological recordings of KV4.3/DREAM channels, we have identified IQM-266 as a DREAM ligand. IQM-266 inhibited the KV4.3/DREAM current in a concentration-, voltage-, and time-dependent-manner. By decreasing the peak current and slowing the inactivation kinetics, IQM-266 led to an increase in the transmembrane charge () at a certain range of concentrations. The slowing of the recovery process and the increase of the inactivation from the closed-state inactivation degree are consistent with a preferential binding of IQM-266 to a pre-activated closed state of KV4.3/DREAM channels. Finally, in rat dorsal root ganglion neurons, IQM-266 inhibited the peak amplitude and slowed the inactivation of IA. Overall, the results presented here identify IQM-266 as a new chemical tool that might allow a better understanding of DREAM physiological role as well as modulation of neuronal IA in pathological processes.

Highlights

The Downstream Regulatory Element Antagonist Modulator (DREAM; Carrion et al, 1999), known as KChIP3 (An et al, 2000) or calsenilin (Buxbaum et al, 1998), is a member of the KV channel interacting proteins (KChIPs) belonging to the neuronal calcium sensor (NCS) family (Burgoyne, 2007)
As part of our program of medicinal chemistry searching for DREAM ligands, we performed a high throughput screening of our chemical libraries to evaluate their binding to DREAM using surface plasmon resonance (SPR)
We selected the novel compound 3-(2-(3Phenoxyphenyl)acetamido)-2-naphthoic acid, IQM-266, which showed a KD = 4.63 ± 0.73 μM, and we have investigated its effect on the KV4/DREAM channels currents (Figure 1; for synthesis and full characterization of IQM-266 see ‘‘Materials and Methods’’ section)

Summary

Introduction

The Downstream Regulatory Element Antagonist Modulator (DREAM; Carrion et al, 1999), known as KChIP3 (An et al, 2000) or calsenilin (Buxbaum et al, 1998), is a member of the KV channel interacting proteins (KChIPs) belonging to the neuronal calcium sensor (NCS) family (Burgoyne, 2007). Among other KChIPs, DREAM binding to KV4 channels regulates potassium currents, and neuronal excitability, in response to changes in intracellular calcium. Small molecules that bind to DREAM modify channel function (Gonzalez et al, 2014; Naranjo et al, 2016). In this regard, repaglinide and CL-888 showed an inhibition of the IA (Naranjo et al, 2016), whereas NS5806 is the only described DREAM ligand showing a potentiation of IA under certain conditions (Witzel et al, 2012). It would be of great interest to have broader range of chemical tools that might allow a better understanding of the physiological role of DREAM and the modulation of neuron IA in pathological processes

Methods

Results

Conclusion