Targeting the neuronal calcium sensor DREAM with small-molecules for Huntington’s disease treatment

Abstract

DREAM, a neuronal calcium sensor protein, has multiple cellular roles including the regulation of Ca 2+ and protein homeostasis. We recently showed that reduced DREAM expression or blockade of DREAM activity by repaglinide is neuroprotective in Huntington’s disease (HD). Here we used structure-based drug design to guide the identification of IQM-PC330, which was more potent and had longer lasting effects than repaglinide to inhibit DREAM in cellular and in vivo HD models. We disclosed and validated an unexplored ligand binding site, showing Tyr118 and Tyr130 as critical residues for binding and modulation of DREAM activity. IQM-PC330 binding de-repressed c-fos gene expression, silenced the DREAM effect on K V 4.3 channel gating and blocked the ATF6/DREAM interaction. Our results validate DREAM as a valuable target and propose more effective molecules for HD treatment.

Pharmacological Approaches for the Modulation of the Potassium Channel KV4.x and KChIPs

“…In these experiments, both concentrations produced a negligible inhibition of the current measured both at the charge or at the peak current ( Figure 7 C,D). Thus, these site-directed mutagenesis results are in agreement with the binding pocket derived from the theoretical studies [ 69 ].…”

“…In addition, IQM-PC330 and IQM-PC332 were identified as KChIP3 ligands by a multidisciplinary approach that involved structure-based drug design, organic synthesis, single-site directed mutagenesis, and surface plasmon resonance (SPR) experiments [ 69 ]. Starting from CL-888, the urea linker was replaced by an amide linker, and based on computational studies, a virtual compound library was designed, in which an additional substituted-phenyl ring was incorporated to provide further features for a more efficient interaction with KChIP3.…”

“…However, at greater concentrations than 1 μM, IQM-PC332 produced opposite effects over the inactivation process and, therefore, its inhibitory effects on the current were greater when measured at the maximum peak current than when measured at the charge. Both compounds slowed the recovery process towards values very close to those recorded on K V 4.3 in the absence of KChIP3 [ 69 ]. In this study, the effect of the Tyr to Ala mutations in the K V 4.3/KChIP3 channel complex was also analyzed.…”

“… Binding site of IQM-PC330 and IQM-PC332 [ 69 ]. ( A ) Cartoon representation of the molecular docking complex of KChIP3 bound to IQM-PC330 (right) and IQM-PC332 (left).…”

“… Electrophysiological effects of IQM-PC330 on K V 4.3 and K V 4.3/KChIP3 channels [ 69 ]. ( A ) Bar chart comparing the inhibition of K V 4.3/KChIP3 currents produced by IQM-PC330, measured at the maximum peak current and at the charge.…”