Synaptic efficacy and precision are influenced by the coupling of voltage-gated Ca2+ channels (VGCCs) to vesicles. But because the topography of VGCCs and their proximity to vesicles is unknown, a quantitative understanding of the determinants of vesicular release at nanometer scale is lacking. To investigate this, we combined freeze-fracture replica immunogold labeling of Cav2.1 channels, local [Ca2+] imaging, and patch pipette perfusion of EGTA at the calyx of Held. Between postnatal day 7 and 21, VGCCs formed variable sized clusters and vesicular release became less sensitive to EGTA, whereas fixed Ca2+ buffer properties remained constant. Experimentally constrained reaction-diffusion simulations suggest that Ca2+ sensors for vesicular release are located at the perimeter of VGCC clusters (<30nm) and predict that VGCC number per cluster determines vesicular release probability without altering release time course. This "perimeter release model" provides a unifying framework accounting for developmental changes in both synaptic efficacy and time course.
This work was supported by the Core Research for Evolutional Science and Technology (CREST) of Japan Science and Technology Agency to T.T. and R.S.; by the funding provided by Okinawa Institute of Science and Technology (OIST) to T.T. and Y.N.; by JSPS Core-to-Core Program, A. Advanced Networks to T.T.; by the Grant-in-Aid for Young Scientists from the Japanese Ministry of Education, Culture, Sports, Science and Technology (#23700474) to Y.N.; by the Centre National de la Recherche Scientifique through the Actions Thematiques et Initatives sur Programme, Fondation Fyssen, Fondation pour la Recherche Medicale, Federation pour la Recherche sur le Cerveau, Agence Nationale de la Recherche (ANR-2007-Neuro-008-01 and ANR-2010-BLAN-1411-01) to D.D. and Y.N.; and by the European Commission Coordination Action ENINET (LSHM-CT-2005-19063) to D.D. and R.A.S. R.A.S. and J.S.R. were funded by Wellcome Trust Senior (064413) and Principal (095667) Research Fellowship and an ERC advance grant (294667) to RAS.
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Nakamura Y, Harada H, Kamasawa N, et al. Nanoscale distribution of presynaptic Ca2+ channels and its impact on vesicular release during development. Neuron. 2015;85(1):145-158. doi:10.1016/j.neuron.2014.11.019
Nakamura, Y., Harada, H., Kamasawa, N., Matsui, K., Rothman, J., Shigemoto, R., … Takahashi, T. (2015). Nanoscale distribution of presynaptic Ca2+ channels and its impact on vesicular release during development. Neuron, 85(1), 145–158. https://doi.org/10.1016/j.neuron.2014.11.019
Nakamura, Yukihiro, Harumi Harada, Naomi Kamasawa, Ko Matsui, Jason Rothman, Ryuichi Shigemoto, R Angus Silver, David Digregorio, and Tomoyuki Takahashi. “Nanoscale Distribution of Presynaptic Ca2+ Channels and Its Impact on Vesicular Release during Development.” Neuron 85, no. 1 (2015): 145–58. https://doi.org/10.1016/j.neuron.2014.11.019.
Y. Nakamura et al., “Nanoscale distribution of presynaptic Ca2+ channels and its impact on vesicular release during development,” Neuron, vol. 85, no. 1, pp. 145–158, 2015.
Nakamura Y, Harada H, Kamasawa N, Matsui K, Rothman J, Shigemoto R, Silver RA, Digregorio D, Takahashi T. 2015. Nanoscale distribution of presynaptic Ca2+ channels and its impact on vesicular release during development. Neuron. 85(1), 145–158.
Nakamura, Yukihiro, et al. “Nanoscale Distribution of Presynaptic Ca2+ Channels and Its Impact on Vesicular Release during Development.” Neuron, vol. 85, no. 1, Elsevier, 2015, pp. 145–58, doi:10.1016/j.neuron.2014.11.019.