The Immediately Releasable Pool of Mouse Chromaffin Cell Vesicles Is Coupled to P/Q-Type Calcium Channels via the Synaptic Protein Interaction Site

• Autores: Álvarez, Y.D.; Belingheri, A.V.; Perez Bay, A.E.; Javis, S.E.; Tedford, H.W.; Zamponi, G.; Marengo, F.D.
• Año de publicación: 2013
• Idioma: inglés
• Tipo de recurso: artículo
• Fuente: PLoS ONE 2013;8(1)
• Materia: calcium channel P type; calcium channel Q type; omega agatoxin IVA; potassium ion; animal cell; article; binding site; calcium current; cell interaction; cell vacuole; chromaffin cell; controlled study; depolarization; exocytosis; mouse; nerve cell stimulation; nonhuman; protein expression; protein interaction; sequence analysis; synapse; transient expression; Animals; Calcium; Calcium Channels, P-Type; Calcium Channels, Q-Type; Cells, Cultured; Chromaffin Cells; Exocytosis; Mice; Secretory Vesicles
• Institución: Universidad Nacional de Buenos Aires. Facultad de Ciencias Exactas y Naturales

It is generally accepted that the immediately releasable pool is a group of readily releasable vesicles that are closely associated with voltage dependent Ca2+ channels. We have previously shown that exocytosis of this pool is specifically coupled to P/Q Ca2+ current. Accordingly, in the present work we found that the Ca2+ current flowing through P/Q-type Ca2+ 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 Ca2+ 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 Ca2+ channels. © 2013 Álvarez et al.
Fil:Álvarez, Y.D. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina.
Fil:Belingheri, A.V. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina.
Fil:Perez Bay, A.E. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina.
Fil:Marengo, F.D. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina.