info:eu-repo/semantics/article
Ca2+-independent and voltage-dependent exocytosis in mouse chromaffin cells
Fecha
2020-04Registro en:
Moya Diaz, José Abelino; Bayonés, Lucas; Montenegro, Mauricio Norman; Cárdenas, Ana M; Koch, Henner; et al.; Ca2+-independent and voltage-dependent exocytosis in mouse chromaffin cells; Wiley Blackwell Publishing, Inc; Acta Physiologica; 228; 4; 4-2020; 1-19
1748-1708
CONICET Digital
CONICET
Autor
Moya Diaz, José Abelino
Bayonés, Lucas
Montenegro, Mauricio Norman
Cárdenas, Ana M
Koch, Henner
Doi, Atsushi
Marengo, Fernando Diego
Resumen
Aim: It is widely accepted that the exocytosis of synaptic and secretory vesicles is triggered by Ca2+ entry through voltage-dependent Ca2+ channels. However, there is evidence of an alternative mode of exocytosis induced by membrane depolarization but lacking Ca2+ current and intracellular Ca2+ increase. In this work we investigated if such a mechanism contributes to secretory vesicle exocytosis in mouse chromaffin cells. Methods: Exocytosis was evaluated by patch-clamp membrane capacitance measurements, carbon fibre amperometry and TIRF. Cytosolic Ca2+ was estimated using epifluorescence microscopy and fluo-8 (salt form). Results: Cells stimulated by brief depolatizations in absence of extracellular Ca+2 show moderate but consistent exocytosis, even in presence of high cytosolic BAPTA concentration and pharmacological inhibition of Ca+2 release from intracellular stores. This exocytosis is tightly dependent on membrane potential, is inhibited by neurotoxin Bont-B (cleaves the v-SNARE synaptobrevin), is very fast (saturates with time constant <10 ms), it is followed by a fast endocytosis sensitive to the application of an anti-dynamin monoclonal antibody, and recovers after depletion in <5 s. Finally, this exocytosis was inhibited by: (i) ω-agatoxin IVA (blocks P/Q-type Ca2+ channel gating), (ii) in cells from knock-out P/Q-type Ca2+ channel mice, and (iii) transfection of free synprint peptide (interferes in P/Q channel-exocytic proteins association). Conclusion: We demonstrated that Ca2+-independent and voltage-dependent exocytosis is present in chromaffin cells. This process is tightly coupled to membrane depolarization, and is able to support secretion during action potentials at low basal rates. P/Q-type Ca2+ channels can operate as voltage sensors of this process.