Ablation of α2δ-1 inhibits cell-surface trafficking of endogenous N-type calcium channels in the pain pathway in vivo
Nieto-Rostro M, Ramgoolam K, Pratt WS, Kulik A, Dolphin AC.
The auxiliary alpha2delta calcium channel subunits play key roles in voltage-gated calcium channel function. Independent of this, alpha2delta-1 has also been suggested to be important for synaptogenesis. Using an epitope-tagged knockin mouse strategy, we examined the effect of alpha2delta-1 on Cav2.2 localization in the pain pathway in vivo, where Cav2.2 is important for nociceptive transmission and alpha2delta-1 plays role in neuropathic pain. We find Cav2.2 is preferentially expressed on the plasma membrane of small nociceptors. This is paralleled by strong presynaptic expression of Cav2.2 in the superficial spinal cord dorsal horn. EM-immunogold localization shows Cav2.2 predominantly in active zones of glomerular primary afferent terminals. Genetic ablation of alpha2delta-1 abolishes Cav2.2 cell-surface expression in DRG neurons and dramatically reduces dorsal horn expression. There was no effect of alpha2delta-1 knockout on other dorsal horn pre- and postsynaptic markers, indicating the primary afferent pathways are not affected by alpha2delta-1 ablation.