Small-molecule Ca _V α ₁ ⋅Ca _V β antagonist suppresses neuronal voltage-gated calcium-channel trafficking

Abstract

Extracellular calcium flow through neuronal voltage-gated CaV2.2 calcium channels converts action potential-encoded information to the release of pronociceptive neurotransmitters in the dorsal horn of the spinal cord, culminating in excitation of the postsynaptic central nociceptive neurons. The CaV2.2 channel is composed of a pore-forming α1subunit (CaVα1) that is engaged in protein–protein interactions with auxiliary α2/δ and β subunits. The high-affinity CaV2.2α1⋅CaVβ3protein–protein interaction is essential for proper trafficking of CaV2.2 channels to the plasma membrane. Here, structure-based computational screening led to small molecules that disrupt the CaV2.2α1⋅CaVβ3protein–protein interaction. The binding mode of these compounds reveals that three substituents closely mimic the side chains of hot-spot residues located on the α-helix of CaV2.2α1. Site-directed mutagenesis confirmed the critical nature of a salt-bridge interaction between the compounds and CaVβ3Arg-307. In cells, compounds decreased trafficking of CaV2.2 channels to the plasma membrane and modulated the functions of the channel. In a rodent neuropathic pain model, the compounds suppressed pain responses. Small-molecule α-helical mimetics targeting ion channel protein–protein interactions may represent a strategy for developing nonopioid analgesia and for treatment of other neurological disorders associated with calcium-channel trafficking.

Partners in Crime: Towards New Ways of Targeting Calcium Channels

“…As a conclusion, many approaches using permeant peptides but also nonpeptidic synthetic molecules [42,43] have managed to alter the interaction between voltage-dependent calcium channel partners in order to successfully reverse various symptoms associated with different pathologies. These interactions are summarized in Figure 1.…”

Emerging roles for multifunctional ion channel auxiliary subunits in cancer

“…In general, Ca v βs increase current density and regulate activation/inactivation kinetics. For instance, disruption of the Ca v β 3 -Ca V 2.2 interaction by a small molecule inhibitor results in a decrease in current density and a depolarised shift in the voltage threshold of activation and inactivation [ 29 ]. In comparison, Ca v β 2 enhances the current density more than Ca v β 3 , potentially through increased membrane expression as Ca v β 2a , unlike Ca v β 3 , contains a palmitoylation site [ 30 ].…”

A potent voltage-gated calcium channel inhibitor engineered from a nanobody targeted to auxiliary CaVβ subunits

“…For example, gabapentin, which is clinically utilized for treating epilepsy and neuropathic pain, targets HVACC α 2 -δ subunits (Gee et al, 1996). Based on the presumption that the association of α 1 with β is obligatory for the formation of surface-targeted functional HVACCs as indicated by heterologous expression experiments (Buraei and Yang, 2010), disruption of the α 1 -β interaction has been long pursued as a strategy to develop HVACC inhibitors (Young et al, 1998; Findeisen et al, 2017; Chen, 2018; Khanna et al, 2019). To this end, over-expression of peptides derived from the α 1 -interaction domain (AID) which contains the amino acid sequence responsible for high-affinity α 1 -β association (Pragnell et al, 1994; Van Petegem et al, 2004; Chen et al, 2004; Opatowsky et al, 2003), has been utilized by several groups as putative genetically-encoded HVACC inhibitors (Findeisen et al, 2017; Yang et al, 2019).…”