- Title
- Two modes of excytosis from synaptosomes are differentially regulated by protein phosphatase types 2A and 2B
- Creator
- Baldwin, Monique L.; Rostas, John A. P.; Sim, Alistair T. R.
- Relation
- Journal of Neurochemistry Vol. 85, Issue 5, p. 1190-1199
- Publisher Link
- http://dx.doi.org/10.1046/j.1471-4159.2003.01779.x
- Publisher
- Blackwell Publishing Ltd
- Resource Type
- journal article
- Date
- 2003
- Description
- The inhibitors okadaic acid (OA), fostriecin (FOS) and cyclosporin A (CsA), were used to investigate the roles of protein phosphatases in regulating exocytosis in rat brain synaptosomes by measuring glutamate release and the release of the styryl dye FM 2-10. Depolarization was induced by 30 mm KCl, or 0.3 mm or 1 mm 4-aminopyridine (4AP). OA and FOS produced a similar partial inhibition of KCl- and 0.3 mm 4AP- evoked exocytosis in both assays, but had little effect upon exocytosis evoked by 1 mm 4AP. In contrast, CsA had no effect upon KCl- and 0.3 mm 4AP-evoked exocytosis, but significantly enhanced glutamate release but not FM 2-10 dye release evoked by 1 mm 4AP. None of the phosphatase inhibitors changed calcium signals from FURA-2-loaded synaptosomes either before or after depolarization. Pretreatment with 100 nm phorbol 12-myristate 13-acetate abolished the inhibitory effect of OA on exocytosis induced by 0.3 mm 4AP. Taken together, these results show that exocytosis from synaptosomes has a phosphatase-sensitive and phosphatase-insensitive component, and that there are two modes of phosphatase-sensitive exocytosis that can be elicited by different depolarization conditions. Moreover, these two modes are differentially sensitive to phosphatase 2A and 2B.
- Subject
- exocytosis; FM 2-10; glutamate; kiss-and-run; protein phosphatase; synaptic vesicle
- Identifier
- uon:1634
- Identifier
- http://hdl.handle.net/1959.13/27401
- Identifier
- ISSN:0022-3042
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