Synaptotagmin 1 directs repetitive release by coupling vesicle exocytosis to the Rab3 cycle

  1. Yunsheng Cheng
  2. Jiaming Wang
  3. Yu Wang
  4. Mei Ding  Is a corresponding author
  1. Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, China
  2. University of Chinese Academy of Sciences, China
  3. Center for Excellence in Brain Science, Chinese Academy of Sciences, China
7 figures

Figures

Figure 1 with 1 supplement
RAB-3 synaptic vesicle association requires SNT-1.

(A) Punctate distribution of GFP::RAB-3 in C. elegans motor neurons in wild-type animals (top). The GFP::RAB-3 puncta become diffuse in aex-3, rep-1, hmgs-1, and snt-1 mutants (lower panels). Yellow …

https://doi.org/10.7554/eLife.05118.003
Figure 1—figure supplement 1
snt-1 is require for RAB-3 synaptic vesicle localization.

(A) Multiple snt-1 alleles show the diffuse GFP::RAB-3 phenotype. White arrows indicate the cell bodies. (B) GFP::RAB-3 expressed pan-neuronally under the control of the Prab-3 promoter displays …

https://doi.org/10.7554/eLife.05118.004
Synaptic vesicle clustering is unaffected by loss of snt-1 function.

(A) SNB-1::GFP puncta distribution in wild type and snt-1 mutants. (B) The synaptic enrichment of SNB-1::GFP puncta is indistinguishable in wild type and snt-1. Data are presented as mean ± SD; NS, …

https://doi.org/10.7554/eLife.05118.005
The GTP-bound form of RAB-3 is decreased in snt-1 mutants.

(A) A GST-fused RBD domain of RIM2 binds active GTP-RAB-3. The amount of GTP-RAB-3 pulled down by RBD is decreased in both aex-3 and snt-1 animals. (B) Quantification of the GTP-RAB-3 level in wild …

https://doi.org/10.7554/eLife.05118.006
Figure 4 with 1 supplement
RAB-3 GAP mutations suppress the snt-1 mutant phenotype.

(A) The punctate distribution of GFP::RAB-3 is restored in rbg-1;snt-1 animals, while the aex-3 phenotype could not be suppressed by mutation of rbg-1. Yellow arrows indicate the cell bodies along …

https://doi.org/10.7554/eLife.05118.007
Figure 4—figure supplement 1
rbg-2 suppresses the snt-1 mutant phenotype.

(A) Schematic representation of the rbg-1(ok1660) deletion mutation. (B) Schematic representation of the rbg-2(ok3195) deletion mutation. Solid boxes indicate exons and thin lines indicate introns. …

https://doi.org/10.7554/eLife.05118.008
Localization of RBG-1 on synaptic vesicles requires SNT-1.

(A and B) mCherry::RBG-1 has a punctate distribution in wild type (A) but accumulates in cell bodies (yellow arrows) in unc-104 mutants (B). (C) mCherry::RBG-1 (red) is co-localized with SNB-1::GFP …

https://doi.org/10.7554/eLife.05118.009
RBG-1 associates with the C2B domain of SNT-1.

(A) RBG-1 is precipitated by the intracellular domain (C2AB) of SNT-1. (B) The SNT-1 intracellular domain is precipitated by RBG-1. (C) The C2B domain of SNT-1 binds to RBG-1. (D) SNT-1 without the …

https://doi.org/10.7554/eLife.05118.010
Figure 7 with 1 supplement
Dissociation of RAB-3 from synaptic vesicles requires the Ca2+-binding activity of SNT-1.

(A) Ca2+ treatment diminishes the binding between RBG-1 and the intracellular domain (C2AB) of SNT-1. (B) Quantification of the relative binding between RBG-1 and the C2AB domain upon Ca2+

https://doi.org/10.7554/eLife.05118.011
Figure 7—figure supplement 1
Exocytosis is uncoupled from RAB-3 synaptic vesicle dissociation in snt-1 mutants.

(A) The failure of RAB-3/SV dissociation caused by exocytosis mutants, including unc-2 and unc-13, is bypassed by mutation of snt-1. Yellow arrows indicate the cell bodies along the ventral cord. …

https://doi.org/10.7554/eLife.05118.012

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