T-type channels-secretion coupling: evidence for a fast low-threshold exocytosis

Carbone, E.; Marcantoni, A.; Giancippoli, A.; Guido, D.; Carabelli, V.
December 2006
Pflugers Archiv European Journal of Physiology;Dec2006, Vol. 453 Issue 3, p373
Academic Journal
T-type channels are transient low-voltage-activated (LVA) Ca2+ channels that control Ca2+ entry in excitable cells during small depolarizations around resting potential. Studies in the past 20 years focused on the biophysical, physiological, and molecular characterization of T-type channels in most tissues. This led to a well-defined picture of the functional role of LVA channels in controlling low-threshold spikes, oscillatory cell activity, muscle contraction, hormone release, cell growth and differentiation. So far, little attention has been devoted to the role of T-type channels in transmitter release, which mainly involves channel types belonging to the high-voltage-activated (HVA) Ca2+ channel family. However, evidence is accumulating in favor of a unique participation of T-type channels in fast transmitter release. Clear data are now reported in reciprocal synapses of the retina and olfactory bulb, synaptic contacts between primary afferent and second order nociceptive neurons, rhythmic inhibitory interneurons of invertebrates and clonal cell lines transfected with recombinant α1 channel subunits. T-type channels also regulate the large dense-core vesicle release of neuroendocrine cells where Ca2+ dependence, rate of vesicle release, and size of readily releasable pool appear comparable to those associated to HVA channels. This suggests that when sufficiently expressed and properly located near the release zones, T-type channels can trigger fast low-threshold secretion. In this study, we will review the main findings that assign a specific task to T-type channels in fast exocytosis, discussing their possible involvement in the control of the Ca2+-dependent processes regulating exocytosis like vesicle depletion and vesicle recycling.


Related Articles

  • Profilin2 contributes to synaptic vesicle exocytosis, neuronal excitability, and novelty-seeking behavior. Pilo Boyl, Pietro; Di Nardo, Alessia; Mulle, Christophe; Sassoè-Pognetto, Marco; Panzanelli, Patrizia; Mele, Andrea; Kneussel, Matthias; Costantini, Vivian; Perlas, Emerald; Massimi, Marzia; Vara, Hugo; Giustetto, Maurizio; Witke, Walter // EMBO Journal;6/20/2007, Vol. 26 Issue 12, p2991 

    Profilins are actin binding proteins essential for regulating cytoskeletal dynamics, however, their function in the mammalian nervous system is unknown. Here, we provide evidence that in mouse brain profilin1 and profilin2 have distinct roles in regulating synaptic actin polymerization with...

  • Tomosyn Inhibits Synaptic Vesicle Priming in Caenorhabditis elegans. Gracheva, Elena O.; Burdina, Anna O.; Holgado, Andrea M.; Berthelot-Grosjean, Martine; Ackley, Brian D.; Hadwiger, Gayla; Nonet, Michael L.; Weimer, Robby M.; Richmond, Janet E. // PLoS Biology;Aug2006, Vol. 4 Issue 8, pe261 

    Caenorhabditis elegans TOM-1 is orthologous to vertebrate tomosyn, a cytosolic syntaxin-binding protein implicated in the modulation of both constitutive and regulated exocytosis. To investigate how TOM-1 regulates exocytosis of synaptic vesicles in vivo, we analyzed C. elegans tom-1 mutants. ...

  • Real-time measurements of vesicle-SNARE recycling in synapses of the central nervous system. Sankaranarayanan, Sethuraman; Ryan, Timothy A. // Nature Cell Biology;Apr2000, Vol. 2 Issue 4, p197 

    Following the fusion of synaptic vesicles with the presynaptic plasma membrane of nerve terminals by the process of exocytosis, synaptic-vesicle components are recycled to replenish the vesicle pool. Here we use a pH-sensitive green fluorescent protein to measure the residence time of VAMP, a...

  • Structural and Mutational Analysis of Functional Differentiation between Synaptotagmins-1 and -7. Mingshan Xue; Craig, Timothy K.; Ok-Ho Shin; Liyi Li; Brautigam, Chad A.; Tomchick, Diana R.; Südhof, Thomas C.; Rosenmund, Christian; Rizo, Josep // PLoS ONE;2010, Vol. 5 Issue 9, p1 

    Synaptotagmins are known to mediate diverse forms of Ca2+-triggered exocytosis through their C2 domains, but the principles underlying functional differentiation among them are unclear. Synaptotagmin-1 functions as a Ca2+ sensor in neurotransmitter release at central nervous system synapses, but...

  • Temporal and spatial coordination of exocytosis and endocytosis. Gundelfinger, Eckart D.; Kessels, Michael M.; Qualmann, Britta // Nature Reviews Molecular Cell Biology;Feb2003, Vol. 4 Issue 2, p127 

    In secretory cells, exocytosis and compensatory endocytosis are tightly coupled membrane trafficking processes that control the surface area and composition of the plasma membrane. While exocytic and endocytic processes have been studied independently in great detail, at present there is much...

  • Lamellar Body Exocytosis by Cell Stretch or Purinergic Stimulation: Possible Physiological Roles, Messengers and Mechanisms. Dietl, Paul; Liss, Birgit; Felder, Edward; Miklavc, Pika; Wirtz, Hubert // Cellular Physiology & Biochemistry (Karger AG);2010, Vol. 25 Issue 1, p001 

    A major function of the pulmonary alveolar type II cell is the secretion of surfactant, a lipoprotein-like substance, via exocytosis of secretory vesicles termed lamellar bodies (LBs). The process of surfactant secretion is remarkable in several aspects, considering stimulus-delayed fusion...

  • A simulation study on the Ca2+-independent but voltage-dependent exocytosis and endocytosis in dorsal root ganglion neurons. Hua Yang; Chen Zhang; Hui Zheng; Wei Xiong; Zhuan Zhou; Tao Xu; Jiu Ding // European Biophysics Journal;Nov2005, Vol. 34 Issue 8, p1007 

    In patch-clamped somata of dorsal root ganglion (DRG) neurons, two types of secretion have been proposed: Ca2+-dependent secretion and Ca2+-independent but voltage-dependent secretion (CIVDS). The Ca2+-induced and the depolarization-induced membrane capacitance ( C m) increases contribute 80 and...

  • Binding of the complexin N terminus to the SNARE complex potentiates synaptic-vesicle fusogenicity. Mingshan Xue; Craig, Timothy K.; Junjie Xu; Chao, Hsiao-Tuan; Rizo, Josep; Rosenmund, Christian // Nature Structural & Molecular Biology;May2010, Vol. 17 Issue 5, p568 

    Complexins facilitate and inhibit neurotransmitter release through distinct domains, and their function was proposed to be coupled to the Ca2+ sensor synaptotagmin-1 (Syt1). However, the mechanisms underlying complexin function remain unclear. We now uncover an interaction between the complexin...

  • The molecular machinery of synaptic vesicle exocytosis. Li, L.; Chin, L.-S. // Cellular & Molecular Life Sciences;May2003, Vol. 60 Issue 5, p942 

    : At the synapse, neurotransmitters are released via Ca2+-triggered exocytotic fusion of synaptic vesicles with the presynaptic plasma membrane. Synaptic vesicle exocytosis seems to share many basic principles and homologous proteins with other membrane fusion events. Conserved components of the...


Read the Article


Sorry, but this item is not currently available from your library.

Try another library?
Sign out of this library

Other Topics