A biallelic mutation in CACNA2D2 associated with developmental and epileptic encephalopathy affects calcium channel-dependent as well as synaptic functions of αδ-2.

αδ proteins serve as auxiliary subunits of voltage-gated calcium channels and regulate channel membrane expression and current properties. Besides their channel function, αδ proteins regulate synapse formation, differentiation, and synaptic wiring. Considering these important functions, it is not surprising that CACNA2D1-4, the genes encoding for αδ-1 to -4 isoforms, have been implicated in neurological, neurodevelopmental, and neuropsychiatric disorders.

An ex vivo Model of Paired Cultured Hippocampal Neurons for Bi-directionally Studying Synaptic Transmission and Plasticity.

Synapses provide the main route of signal transduction within neuronal networks. Many factors regulate critical synaptic functions. These include presynaptic calcium channels, triggering neurotransmitter release, and postsynaptic ionotropic receptors, mediating excitatory and inhibitory postsynaptic potentials.

Presynaptic αδ subunits are key organizers of glutamatergic synapses.

In nerve cells the genes encoding for αδ subunits of voltage-gated calcium channels have been linked to synaptic functions and neurological disease. Here we show that αδ subunits are essential for the formation and organization of glutamatergic synapses. Using a cellular αδ subunit triple-knockout/knockdown model, we demonstrate a failure in presynaptic differentiation evidenced by defective presynaptic calcium channel clustering and calcium influx, smaller presynaptic active zones, and a strongly reduced accumulation of presynaptic vesicle-associated proteins (synapsin and vGLUT).

Neuronal αδ proteins and brain disorders.

αδ proteins are membrane-anchored extracellular glycoproteins which are abundantly expressed in the brain and the peripheral nervous system. They serve as regulatory subunits of voltage-gated calcium channels and, particularly in nerve cells, regulate presynaptic and postsynaptic functions independently from their role as channel subunits. αδ proteins are the targets of the widely prescribed anti-epileptic and anti-allodynic drugs gabapentin and pregabalin, particularly for the treatment of neuropathic pain conditions.