ORALS
SESSION: ElectrochemistryMonPM1-R2
| Amatore International Symposium on Electrochemistry for Sustainable Development |
| Mon Nov, 5 2018 / Room: Copacabana B (150/1st) | |
| Session Chairs: Wei-Hua Huang; Session Monitor: TBA |
14:50: [ElectrochemistryMonPM107]
Quantitative Analysis of Fusion Pore Dynamics During Vesicular Exocytosis in Neuroendocrine Cells Alexander
Oleinick1 ;
Irina
Svir2 ;
Christian
Amatore3 ;
1CNRS-ENS-SU UMR 8640 PASTEUR, CNRS, Paris, France;
2Ecole Normale Superieure, Department Chemistry, PARIS, France;
3CNRS & PSL, French Academy of Sciences, Paris, France;
Paper Id: 98
[Abstract] Vesicular exocytosis is a key biological mechanism through which cells communicate with each other or with their environment. It is involved in many systems in our body (e.g. nervous, endocrine, digestive, etc.), which makes its understanding of paramount importance from both fundamental and practical points of view. Amperometric measurements of vesicular exocytosis with ultramicroelectrode in artificial synapse configuration [1] provide two important advantages: unsurpassed temporal resolution on emitted fluxes of neurotransmitter during single exocytotic events and possibility to obtain massive data. These two advantages allow statistical analysis of exocytotic events and observe trends in different cell types and/or under various physico-chemical conditions (osmotic shocks, effect of drugs etc.). However, generally statistical analysis is restricted to the examination of some shape features of the amperometric spikes (half-peak time width, charge released etc.) representing individual exocytotic events, even though all relevant physico-chemical parameters are intricately convoluted in the monitored current. Extraction of these thought parameters is extremely difficult, due to the fact that each exocytotic event is unique in terms of vesicle size, its internal composition, neurotransmitter load etc. We developed a theoretical framework providing means to extract statistically sound fusion pore sizes during exocytotic event from individual amperometric spikes [2-3], that is the information hardly accessible or not accessible by other approaches. This permits us to analyze and quantify vesicle pore sizes from amperometric data obtained at bovine chromaffin cells [4].
Recently we dramatically simplified the fusion pore size extraction procedure (without sacrificing its accuracy) so that it can be easily implemented by the experimentalists, e.g. in spreadsheet or general purpose mathematical software. This advance allow us to address a larger data set of spikes obtained at chromaffin cells and reveal statistical changes in fusion pores topology under modified conditions (osmotic stress, modification of cell membrane with exogeneous lipids) with respect to control conditions. Of high interest was the finding that in all considered cases the fusion pore radius was never larger than 30 nm, that is much smaller to the average radius of the chromaffin cell vesicle (156 nm). Taking into account significant size of the data set (more than 1000 spikes) this questions the 'inevitable full fusion' paradigm and statistically support a mode of exocytosis where the pore size is significantly smaller the vesicle size [4].
References:
[1] C. Amatore, S. Arbault, M. Guille, F. Lemaitre. Chem. Rev. 108 (2008) 2585-2621.
[2] C. Amatore, A. Oleinick, I. Svir. ChemPhysChem 11 (2010) 149-158; 159-174.
[3] A. Oleinick, F. Lemaitre, M. Guille Collignon, I. Svir, C. Amatore. Faraday Discuss. 164 (2013) 33-55.
[4] A. Oleinick, I. Svir, C. Amatore. Proc. Roy. Soc. A 473 (2017) 20160684.
