SNAP-25 gene family members differentially support secretory vesicle fusion

• Published in: Journal of cell science Vol. 130; no. 11; pp. 1877 - 1889
• Main Authors: Arora, Swati, Saarloos, Ingrid, Kooistra, Robbelien, van de Bospoort, Rhea, Verhage, Matthijs, Toonen, Ruud F
• Format: Journal Article
• Language: English
• Published: England The Company of Biologists Ltd 01-06-2017
• Subjects: Animals; Biological Transport; Cell Death - genetics; Degeneration; Dense core vesicles; Developmental plasticity; Embryo, Nonmammalian; Exocytosis; Gene Expression Regulation; Genetic Complementation Test; Hippocampus; Hippocampus - metabolism; Hippocampus - pathology; Homology; Membrane Fusion; Mice; Mice, Knockout; Neurons; Neurons - metabolism; Neurons - pathology; Neuropeptides; Presynaptic Terminals - metabolism; Presynaptic Terminals - pathology; Primary Cell Culture; Protein Isoforms - genetics; Protein Isoforms - metabolism; Qb-SNARE Proteins - genetics; Qb-SNARE Proteins - metabolism; Qc-SNARE Proteins - genetics; Qc-SNARE Proteins - metabolism; Secretory Vesicles - metabolism; Secretory Vesicles - pathology; SNAP-23 protein; SNAP-25 protein; Survival; Synaptic Transmission; Synaptosomal-Associated Protein 25 - deficiency; Synaptosomal-Associated Protein 25 - genetics; Vesicle fusion; Viability; Hippocampal neuron; Fusion; SNAP-25; Neuropeptide vesicle
• ISSN: 0021-9533; 1477-9137
• DOI: 10.1242/jcs.201889

Neuronal dense-core vesicles (DCVs) transport and secrete neuropeptides necessary for development, plasticity and survival, but little is known about their fusion mechanism. We show that
-null mutant (SNAP-25 KO) neurons, previously shown to degenerate after 4 days
(DIV), contain fewer DCVs and have reduced DCV fusion probability in surviving neurons at DIV14. At DIV3, before degeneration, SNAP-25 KO neurons show normal DCV fusion, but one day later fusion is significantly reduced. To test if other SNAP homologs support DCV fusion, we expressed SNAP-23, SNAP-29 or SNAP-47 in SNAP-25 KO neurons. SNAP-23 and SNAP-29 rescued viability and supported DCV fusion in SNAP-25 KO neurons, but SNAP-23 did so more efficiently. SNAP-23 also rescued synaptic vesicle (SV) fusion while SNAP-29 did not. SNAP-47 failed to rescue viability and did not support DCV or SV fusion. These data demonstrate a developmental switch, in hippocampal neurons between DIV3 and DIV4, where DCV fusion becomes SNAP-25 dependent. Furthermore, SNAP-25 homologs support DCV and SV fusion and neuronal viability to variable extents - SNAP-23 most effectively, SNAP-29 less so and SNAP-47 ineffectively.