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A role for SNAP‐25 but not VAMPs in store‐mediated Ca 2+ entry in human platelets
Author(s) -
Redondo Pedro C.,
Harper Alan G. S.,
Salido Ginés M.,
Pariente Jose A.,
Sage Stewart O.,
Rosado Juan A.
Publication year - 2004
Publication title -
the journal of physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.802
H-Index - 240
eISSN - 1469-7793
pISSN - 0022-3751
DOI - 10.1113/jphysiol.2004.064899
Subject(s) - chemistry , receptor , platelet , biophysics , vesicle , microbiology and biotechnology , agonist , cytosol , biochemistry , membrane , biology , enzyme , immunology
Store‐mediated Ca 2+ entry (SMCE) is a major mechanism for Ca 2+ influx in non‐excitable cells. Recently, a conformational coupling mechanism allowing coupling between transient receptor potential channels (TRPCs) and IP 3 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 Ca 2+ 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 IP 3 receptor type II in platelets. From these findings we suggest SNAP‐25 has a role in SMCE in human platelets.