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Piccolo modulation of Synapsin1a dynamics regulates synaptic vesicle exocytosis
Correspondence to C.C. Garner: cgarner{at}stanford.edu
Active zones are specialized regions of the presynaptic plasma membrane designed for the efficient and repetitive release of neurotransmitter via synaptic vesicle (SV) exocytosis. Piccolo is a high molecular weight component of the active zone that is hypothesized to participate both in active zone formation and the scaffolding of key molecules involved in SV recycling. In this study, we use interference RNAs to eliminate Piccolo expression from cultured hippocampal neurons to assess its involvement in synapse formation and function. Our data show that Piccolo is not required for glutamatergic synapse formation but does influence presynaptic function by negatively regulating SV exocytosis. Mechanistically, this regulation appears to be calmodulin kinase II–dependent and mediated through the modulation of Synapsin1a dynamics. This function is not shared by the highly homologous protein Bassoon, which indicates that Piccolo has a unique role in coupling the mobilization of SVs in the reserve pool to events within the active zone.
Abbreviations used in this paper: ANOVA, analysis of variance; AZ, active zone; CaMKII, CaM-dependent kinase II; CAZ, cytoskeletal matrix assembled at the active zone; DIV, days in vitro; MAP2, microtubule-associated protein 2; Pr, probability of release; PSD, postsynaptic density; RRP, readily releasable pool; shRNA, short hairpin RNA; SV, synaptic vesicle; TRP, total recycling pool; VAMP2, vesicle-associated membrane protein 2.
© 2008 Leal-Ortiz et al. This article is distributed under the terms of an Attribution–Noncommercial–Share Alike–No Mirror Sites license for the first six months after the publication date (see http://www.jcb.org/misc/terms.shtml). After six months it is available under a Creative Commons License (Attribution–Noncommercial–Share Alike 3.0 Unported license, as described at http://creativecommons.org/licenses/by-nc-sa/3.0/).
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