title: SNAP-25 Ser187 does not mediate phorbol ester enhancement of hippocampal synaptic transmission.
abstract: Phorbol esters, activators of protein kinase C (PKC), have been shown to enhance synaptic transmission. One potential downstream target of PKC in the presynaptic terminal is the soluble N-ethylmaleimide sensitive factor (NSF) attachment protein receptor (SNARE) SNAP-25, which has a PKC phosphorylation site in its C-terminal coil centered at serine 187 (S187/Ser187). We examined the role of S187 in hippocampal synaptic transmission. After proteolytic cleavage of native SNAP-25 by botulinum neurotoxin E (BoNT/E), synaptic transmission was restored in a subset of transfected CA3 pyramidal cells with a toxin-resistant form of SNAP-25 containing unaltered S187 (Swt), S187 mutated to alanine (SA) or S187 mutated to glutamate (SE). We observed that phorbol-12,13-diacetate (PDAc, 10 microM) induced potentiation of neurotransmission to a similar degree for both Swt and SA (2.4-fold and 3.1-fold increase, respectively). Furthermore, basal levels of transmission mediated by SE were reduced relative to that of Swt (failure rates of 72% and 41%, respectively). Together, these data suggest that phosphorylation of SNAP-25 S187 does not mediate the observed enhancement of neurotransmission by phorbol esters at hippocampal synapses.
authors.affiliation: Howard Hughes Medical Institute, Stanford University School of Medicine, Beckman Center B003, Stanford, CA 94305, USA. mfinley1@prdus.jnj.com
authors.forename: Michael F A
authors.initials: MF
authors.lastname: Finley
authors.forename: Richard H
authors.initials: RH
authors.lastname: Scheller
authors.forename: Daniel V
authors.initials: DV
authors.lastname: Madison
mesh_terms: D000818:Animals; D006624:Hippocampus / Q000187:drug effects / Q000378:metabolism*; D008565:Membrane Proteins / Q000235:genetics / Q000502:physiology; D051379:Mice; D009154:Mutation; D009419:Nerve Tissue Proteins / Q000235:genetics / Q000502:physiology; D010703:Phorbol Esters / Q000494:pharmacology*; D010766:Phosphorylation; D012694:Serine / Q000235:genetics / Q000502:physiology*; D009435:Synaptic Transmission / Q000187:drug effects* / Q000235:genetics; D050825:Synaptosomal-Associated Protein 25; D015854:Up-Regulation / Q000187:drug effects / Q000235:genetics
chemical_list: D008565:Membrane Proteins; D009419:Nerve Tissue Proteins; D010703:Phorbol Esters; C494209:Snap25 protein, mouse; D050825:Synaptosomal-Associated Protein 25; C008874:phorbol-12,13-diacetate; D012694:Serine