Snapin, a new regulator of receptor signaling, augments alpha1A-adrenoceptor-operated calcium influx through TRPC6.
Activation of G(q)-protein-coupled receptors, including the alpha(1A)-adrenoceptor (alpha(1A)-AR), causes a sustained Ca(2+) influx via receptor-operated Ca(2+) (ROC) channels, following the transient release of intracellular Ca(2+). 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 Ca(2+) via TRPCs is not yet fully understood. We identified Snapin as a protein interacting with the C terminus of the alpha(1A)-AR. In receptor-expressing PC12 cells, co-transfection of Snapin augmented alpha(1A)-AR-stimulated sustained increases in intracellular Ca(2+) ([Ca(2+)](i)) via ROC channels. By altering the Snapin binding C-terminal domain of the alpha(1A)-AR or by reducing cellular Snapin with short interfering RNA, the sustained increase in [Ca(2+)](i) in Snapin-alpha(1A)-AR co-expressing PC12 cells was attenuated. Snapin co-immunoprecipitated with TRPC6 and alpha(1A)-AR, and these interactions were augmented upon alpha(1A)-AR activation, increasing the recruitment of TRPC6 to the cell surface. Our data suggest a new receptor-operated signaling mechanism where Snapin links the alpha(1A)-AR to TRPC6, augmenting Ca(2+) influx via ROC channels.
Division of Pharmacology, Department of Biochemistry and Bioinformative Sciences, School of Medicine, University of Fukui, 23-3 Matsuoka-Shimoaizuki, Eiheiji, Fukui 910-1193, Japan.
Fumiko
F
Suzuki
Shigeru
S
Morishima
Takashi
T
Tanaka
Ikunobu
I
Muramatsu
D000818:Animals; D002118:Calcium / Q000378:metabolism; D002462:Cell Membrane / Q000378:metabolism; D006801:Humans; D008954:Models, Biological; D016716:PC12 Cells; D017434:Protein Structure, Tertiary; D051381:Rats; D018340:Receptors, Adrenergic, alpha-1 / Q000378:metabolism*; D015398:Signal Transduction; D050052:TRPC Cation Channels / Q000378:metabolism*; D000074287:TRPC6 Cation Channel; D020798:Two-Hybrid System Techniques; D033921:Vesicular Transport Proteins / Q000502:physiology*
D018340:Receptors, Adrenergic, alpha-1; C118519:SNAPIN protein, human; C498452:Snapin protein, rat; D050052:TRPC Cation Channels; D000074287:TRPC6 Cation Channel; C117032:TRPC6 protein, human; C492145:Trpc6 protein, rat; D033921:Vesicular Transport Proteins; D002118:Calcium