A role for SNAP-25 but not VAMPs in store-mediated Ca2+ entry in human platelets
| Autor: | Pedro C, Redondo, Alan G S, Harper, Ginés M, Salido, Jose A, Pariente, Stewart O, Sage, Juan A, Rosado |
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| Rok vydání: | 2004 |
| Předmět: |
Blood Platelets
Botulinum Toxins Synaptosomal-Associated Protein 25 Cell Membrane Thrombin Membrane Proteins Receptors Cytoplasmic and Nuclear Nerve Tissue Proteins Research Papers Hemostatics R-SNARE Proteins Tetanus Toxin Humans Immunoprecipitation Inositol 1 4 5-Trisphosphate Receptors Thapsigargin Calcium Calcium Channels Enzyme Inhibitors TRPC Cation Channels |
| Zdroj: | The Journal of physiology. 558(Pt 1) |
| ISSN: | 0022-3751 |
| Popis: | Store-mediated Ca2+ entry (SMCE) is a major mechanism for Ca2+ influx in non-excitable cells. Recently, a conformational coupling mechanism allowing coupling between transient receptor potential channels (TRPCs) and IP3 receptors has been proposed to activate SMCE. Here we have investigated the role of two soluble N-ethylmaleimide-sensitive-factor attachment protein receptors (SNAREs), which are involved in membrane trafficking and docking, in SMCE in human platelets. We found that the synaptosome-associated protein (SNAP-25) and the vesicle-associated membrane proteins (VAMP) coimmunoprecipitate with hTRPC1 in platelets. Treatment with botulinum toxin (BoNT) E or with tetanus toxin (TeTx), induced cleavage and inactivation of SNAP-25 and VAMPs, respectively. BoNTs significantly reduced thapsigargin- (TG) and agonist-evoked SMCE. Treatment with BoNTs once SMCE had been activated decreased Ca2+ entry, indicating that SNAP-25 is required for the activation and maintenance of SMCE. In contrast, treatment with TeTx had no effect on either the activation or the maintenance of SMCE in platelets. Finally, treatment with BoNT E impaired the coupling between naturally expressed hTRPC1 and IP3 receptor type II in platelets. From these findings we suggest SNAP-25 has a role in SMCE in human platelets. |
| Databáze: | OpenAIRE |
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