The immediately releasable pool of mouse chromaffin cell vesicles is coupled to P/Q-type calcium channels via the synaptic protein interaction site

• Autores: Alvarez, Yanina Daniela; Belingheri, Ana Verónica; Perez Bay, Andrés Ezequiel; Javis, Scott E.; Tedford, H. William; Zamponi, Gerald; Marengo, Fernando Diego
• Año de publicación: 2013
• Idioma: inglés
• Tipo de recurso: artículo
• Materia: IRP; P/Q-type Ca(2+) channels; Synprint; Chromaffin cells
• Institución: Consejo Nacional de Investigaciones Científicas y Técnicas

It is generally accepted that the immediately releasable pool is a group of readily releasable vesicles that are closely associated with voltage dependent Ca(2+) channels. We have previously shown that exocytosis of this pool is specifically coupled to P/Q Ca(2+) current. Accordingly, in the present work we found that the Ca(2+) current flowing through P/Q-type Ca(2+) channels is 8 times more effective at inducing exocytosis in response to short stimuli than the current carried by L-type channels. To investigate the mechanism that underlies the coupling between the immediately releasable pool and P/Q-type channels we transiently expressed in mouse chromaffin cells peptides corresponding to the synaptic protein interaction site of Cav2.2 to competitively uncouple P/Q-type channels from the secretory vesicle release complex. This treatment reduced the efficiency of Ca(2+) current to induce exocytosis to similar values as direct inhibition of P/Q-type channels via ω-agatoxin-IVA. In addition, the same treatment markedly reduced immediately releasable pool exocytosis, but did not affect the exocytosis provoked by sustained electric or high K(+) stimulation. Together, our results indicate that the synaptic protein interaction site is a crucial factor for the establishment of the functional coupling between immediately releasable pool vesicles and P/Q-type Ca(2+) channels.
Fil: Alvarez, Yanina Daniela. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Fisiología, Biología Molecular y Neurociencias; Argentina;
Fil: Belingheri, Ana Verónica. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Fisiología, Biología Molecular y Neurociencias; Argentina;
Fil: Perez Bay, Andrés Ezequiel. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Fisiología, Biología Molecular y Neurociencias; Argentina;
Fil: Javis, Scott E.. University of Calgary. Hotchkiss Brain Institute; Canada;
Fil: Tedford, H. William. University of Calgary. Hotchkiss Brain Institute; Canada;
Fil: Zamponi, Gerald. University of Calgary. Hotchkiss Brain Institute; Canada;
Fil: Marengo, Fernando Diego. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Fisiología, Biología Molecular y Neurociencias; Argentina;