Inhibition of voltage-gated calcium (CaV) channels is a potential therapy for many neurological diseases including chronic pain.
Neuronal CaV1/CaV2 channels are composed of a, b, g and a2d subunits. The b subunits of CaV channels are cytoplasmic proteins
that increase the surface expression of the pore-forming a subunit of CaV. We targeted the high-affinity protein–protein interface of
CaVb’s pocket within the CaVa subunit. Structure-based virtual screening of 50,000 small molecule library docked to the b subunit
led to the identification of 2-(3,5-dimethylisoxazol-4-yl)-N-((4-((3-phenylpropyl)amino)quinazolin-2-yl)methyl)acetamide (IPPQ). This
small molecule bound to CaVb and inhibited its coupling wi... More
Inhibition of voltage-gated calcium (CaV) channels is a potential therapy for many neurological diseases including chronic pain.
Neuronal CaV1/CaV2 channels are composed of a, b, g and a2d subunits. The b subunits of CaV channels are cytoplasmic proteins
that increase the surface expression of the pore-forming a subunit of CaV. We targeted the high-affinity protein–protein interface of
CaVb’s pocket within the CaVa subunit. Structure-based virtual screening of 50,000 small molecule library docked to the b subunit
led to the identification of 2-(3,5-dimethylisoxazol-4-yl)-N-((4-((3-phenylpropyl)amino)quinazolin-2-yl)methyl)acetamide (IPPQ). This
small molecule bound to CaVb and inhibited its coupling with N-type voltage-gated calcium (CaV2.2) channels, leading to
a reduction in CaV2.2 currents in rat dorsal root ganglion sensory neurons, decreased presynaptic localization of CaV2.2 in vivo,
decreased frequency of spontaneous excitatory postsynaptic potentials and miniature excitatory postsynaptic potentials, and
inhibited release of the nociceptive neurotransmitter calcitonin gene–related peptide from spinal cord. IPPQ did not target opioid
receptors nor did it engage inhibitory G protein–coupled receptor signaling. IPPQ was antinociceptive in naive animals and reversed
allodynia and hyperalgesia in models of acute (postsurgical) and neuropathic (spinal nerve ligation, chemotherapy- and gp120-
induced peripheral neuropathy, and genome-edited neuropathy) pain. IPPQ did not cause akinesia or motor impairment, a common
adverse effect of CaV2.2 targeting drugs, when injected into the brain. IPPQ, a quinazoline analog, represents a novel class of
CaV2.2-targeting compounds that may serve as probes to interrogate CaVa–CaVb function and ultimately be developed as
a nonopioid therapeutic for chronic pain.
