title: Synaptotagmin-12 phosphorylation by cAMP-dependent protein kinase is essential for hippocampal mossy fiber LTP.
abstract: Synaptotagmin-12 (Syt12) is an abundant synaptic vesicle protein that--different from other synaptic vesicle-associated synaptotagmins--does not bind Ca(2+). Syt12 is phosphorylated by cAMP-dependent protein kinase-A at serine-97 in an activity-dependent manner, suggesting a function for Syt12 in cAMP-dependent synaptic plasticity. To test this hypothesis, we here generated (1) Syt12 knock-out mice and (2) Syt12 knockin mice carrying a single amino-acid substitution [the serine-97-to-alanine- (S97A)-substitution]. Both Syt12 knock-out mice and Syt12 S97A-knockin mice were viable and fertile, and exhibited no measurable change in basal synaptic strength or short-term plasticity as analyzed in cultured cortical neurons or in acute hippocampal slices. However, both Syt12 knock-out and Syt12 S97A-knockin mice displayed a major impairment in cAMP-dependent mossy-fiber long-term potentiation (LTP) in the CA3 region of the hippocampus. This impairment was observed using different experimental configurations for inducing and monitoring mossy-fiber LTP. Moreover, although the Syt12 knock-out had no effect on the short-term potentiation of synaptic transmission induced by the adenylate-cyclase activator forskolin in cultured cortical neurons and in the CA1 region of the hippocampus, both the Syt12 knock-out and the Syt12 S97A-knockin impaired the long-term increase in mossy-fiber synaptic transmission induced by forskolin. Thus, Syt12 is essential for cAMP-dependent presynaptic LTP at mossy-fiber synapses, and a single amino-acid substitution that blocks the cAMP-dependent phosphorylation of Syt12 is sufficient to impair the function of Syt12 in mossy-fiber LTP, suggesting that cAMP-dependent phosphorylation of Syt12 on serine-97 contributes to the induction of mossy-fiber LTP.
authors.affiliation: Department of Molecular and Cellular Physiology, Stanford University, Stanford California 94304-5453, USA.
authors.forename: Yea Jin
authors.initials: YJ
authors.lastname: Kaeser-Woo
authors.forename: Thomas J
authors.initials: TJ
authors.lastname: Younts
authors.forename: Xiaofei
authors.initials: X
authors.lastname: Yang
authors.forename: Peng
authors.initials: P
authors.lastname: Zhou
authors.forename: Dick
authors.initials: D
authors.lastname: Wu
authors.forename: Pablo E
authors.initials: PE
authors.lastname: Castillo
authors.forename: Thomas C
authors.initials: TC
authors.lastname: Südhof
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D017868:Cyclic AMP-Dependent Protein Kinases / Q000502:physiology*; D055879:Gene Knock-In Techniques; D017774:Long-Term Potentiation / Q000502:physiology*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D019599:Mossy Fibers, Hippocampal / Q000378:metabolism*; D010766:Phosphorylation / Q000502:physiology; D050857:Synaptotagmins / Q000378:metabolism*
chemical_list: D050857:Synaptotagmins; D017868:Cyclic AMP-Dependent Protein Kinases