Activation of Gq-protein-coupled receptors, including the α1A-adrenoceptor (α1A-AR), causes a sustained Ca2+ influx via receptor-operated Ca2+ (ROC) channels, following the transient release of intracellular Ca2+. Transient receptor potential canonical (TRPC) channel is one of the candidate proteins constituting the ROC channels, but the precise mechanism linking receptor activation to increased influx of Ca2+ via TRPCs is not yet fully understood. We identified Snapin as a protein interacting with the C terminus of the α1A-AR. In receptor-expressing PC12 cells, co-transfection of Snapin augmented α1A-AR-stimulated sustained increases in intracellular Ca2+ ([Ca2+]i) via ROC channels. By altering the Snapin binding C-terminal domain of the α1A-AR or by reducing cellular Snapin with short interfering RNA, the sustained increase in [Ca2+]i in Snapin-α1A-AR co-expressing PC12 cells was attenuated. Snapin co-immunoprecipitated with TRPC6 and α1A-AR, and these interactions were augmented upon α1A-AR activation, increasing the recruitment of TRPC6 to the cell surface. Our data suggest a new receptor-operated signaling mechanism where Snapin links the α1A-AR to TRPC6, augmenting Ca2+ influx via ROC channels.
This work was supported in part by grant-in-aid for scientific research from the Japan Society of the Promotion of Science (to F. S. and I. M.) and by the 21st Center of Excellence research program (Medical Science). The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked “advertisement” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.
