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Temperature Dependence of Fusion Kinetics and Fusion Pores in Ca(2+)-triggered Exocytosis from PC12 Cells

The temperature dependence of Ca(2+)-triggered exocytosis was studied using carbon fiber amperometry to record the release of norepinephrine from PC12 cells. Single-vesicle fusion events were examined at temperatures varying from 12 to 28°C, and with release elicited by depolarization. Measurements...

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Detalles Bibliográficos
Autores principales: Zhang, Zhen, Jackson, Meyer B.
Formato: Texto
Lenguaje:English
Publicado: The Rockefeller University Press 2008
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2213568/
https://www.ncbi.nlm.nih.gov/pubmed/18195388
http://dx.doi.org/10.1085/jgp.200709891
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author Zhang, Zhen
Jackson, Meyer B.
author_facet Zhang, Zhen
Jackson, Meyer B.
author_sort Zhang, Zhen
collection PubMed
description The temperature dependence of Ca(2+)-triggered exocytosis was studied using carbon fiber amperometry to record the release of norepinephrine from PC12 cells. Single-vesicle fusion events were examined at temperatures varying from 12 to 28°C, and with release elicited by depolarization. Measurements were made of the initial and maximum frequencies of exocytotic events, of fusion pore lifetime, flux through the open fusion pore, kiss-and-run versus full-fusion probability, and parameters associated with the shapes of amperometric spikes. The fusion pore open-state flux, and all parameters associated with spike shape, including area, rise time, and decay time, had weak temperature dependences and activation energies in the range expected for bulk diffusion in an aqueous solution. Kiss-and-run events also varied with temperature, with lower temperatures increasing the relative probability of kiss-and-run events by ∼50%. By contrast, kinetic parameters relating to the frequency of exocytotic events and fusion pore transitions depended much more strongly on temperature, suggesting that these processes entail structural rearrangements of proteins or lipids or both. The weak temperature dependence of spike shape suggests that after the fusion pore has started to expand, structural transitions of membrane components are no longer kinetically limiting. This indicates that the content of a vesicle is expelled completely after fusion pore expansion.
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spelling pubmed-22135682008-08-01 Temperature Dependence of Fusion Kinetics and Fusion Pores in Ca(2+)-triggered Exocytosis from PC12 Cells Zhang, Zhen Jackson, Meyer B. J Gen Physiol Articles The temperature dependence of Ca(2+)-triggered exocytosis was studied using carbon fiber amperometry to record the release of norepinephrine from PC12 cells. Single-vesicle fusion events were examined at temperatures varying from 12 to 28°C, and with release elicited by depolarization. Measurements were made of the initial and maximum frequencies of exocytotic events, of fusion pore lifetime, flux through the open fusion pore, kiss-and-run versus full-fusion probability, and parameters associated with the shapes of amperometric spikes. The fusion pore open-state flux, and all parameters associated with spike shape, including area, rise time, and decay time, had weak temperature dependences and activation energies in the range expected for bulk diffusion in an aqueous solution. Kiss-and-run events also varied with temperature, with lower temperatures increasing the relative probability of kiss-and-run events by ∼50%. By contrast, kinetic parameters relating to the frequency of exocytotic events and fusion pore transitions depended much more strongly on temperature, suggesting that these processes entail structural rearrangements of proteins or lipids or both. The weak temperature dependence of spike shape suggests that after the fusion pore has started to expand, structural transitions of membrane components are no longer kinetically limiting. This indicates that the content of a vesicle is expelled completely after fusion pore expansion. The Rockefeller University Press 2008-02 /pmc/articles/PMC2213568/ /pubmed/18195388 http://dx.doi.org/10.1085/jgp.200709891 Text en Copyright © 2008, The Rockefeller University Press 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.rupress.org/terms). After six months it is available under a Creative Commons License (Attribution–Noncommercial–Share Alike 4.0 Unported license, as described at http://creativecommons.org/licenses/by-nc-sa/4.0/).
spellingShingle Articles
Zhang, Zhen
Jackson, Meyer B.
Temperature Dependence of Fusion Kinetics and Fusion Pores in Ca(2+)-triggered Exocytosis from PC12 Cells
title Temperature Dependence of Fusion Kinetics and Fusion Pores in Ca(2+)-triggered Exocytosis from PC12 Cells
title_full Temperature Dependence of Fusion Kinetics and Fusion Pores in Ca(2+)-triggered Exocytosis from PC12 Cells
title_fullStr Temperature Dependence of Fusion Kinetics and Fusion Pores in Ca(2+)-triggered Exocytosis from PC12 Cells
title_full_unstemmed Temperature Dependence of Fusion Kinetics and Fusion Pores in Ca(2+)-triggered Exocytosis from PC12 Cells
title_short Temperature Dependence of Fusion Kinetics and Fusion Pores in Ca(2+)-triggered Exocytosis from PC12 Cells
title_sort temperature dependence of fusion kinetics and fusion pores in ca(2+)-triggered exocytosis from pc12 cells
topic Articles
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2213568/
https://www.ncbi.nlm.nih.gov/pubmed/18195388
http://dx.doi.org/10.1085/jgp.200709891
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