Identification that ADAM17 mediates proteolytic maturation of calcium channel auxiliary α2δ subunits, and enables calcium current enhancement

The auxiliary α2δ subunits of voltage-gated calcium (CaV) channels are key to augmenting expression and function of CaV1 and CaV2 channels, and are also important drug targets in several therapeutic areas, including neuropathic pain. The α2δ proteins are translated as pre-proteins encoding both α2 and δ, and post-translationally proteolysed into α2 and δ subunits, which remain associated as a complex. In this study we have identified ADAM17 as a key protease involved in proteolytic processing of pro-α2δ-1 and α2δ-3 subunits. We provide three lines of evidence: firstly, proteolytic cleavage is inhibited by chemical inhibitors of particular metalloproteases, including ADAM17. Secondly, proteolytic cleavage of both α2δ-1 and α2δ-3 is markedly reduced in cell lines by knockout of ADAM17 but not ADAM10 . Thirdly, proteolytic cleavage is reduced by the N-terminal active domain of TIMP-3 (N-TIMP-3), which selectively inhibits ADAM17. We have found previously that proteolytic cleavage into mature α2δ is essential for the enhancement of CaV function, and in agreement, knockout of ADAM17 inhibited the ability of α2δ-1 to enhance both CaV2.2 and CaV1.2 calcium currents. Thus, our study identifies ADAM17 as a key protease required for proteolytic maturation of α2δ-1 and α2δ-3, and thus a potential drug target in neuropathic pain. ### Competing Interest Statement The authors have declared no competing interest.