A new modality of calcium-mediated presynaptic transmitter release

Posted by:

Alfredo Pereira Jr (group admin)

Date:

11 December 2007

Comments:

1 comment

From Nature Neuroscience

Sensors and synchronicity

Ruth Heildelbeger

Synaptic communication is triggered by action potentials, but
neurons also
talk to each other in between action potentials. Specific
intracellular-calcium sensors regulate these conversations… In the
presynaptic neuron, voltage-gated calcium channels are activated in
response
to an action potential, allowing the entry of extracellular calcium.
This
triggers the fusion of neurotransmitter-laden synaptic vesicles with
the
plasma membrane and the release of neurotransmitter molecules. Released
molecules bind to receptors on the postsynaptic neuron, initiating a
postsynaptic response. The close proximity of release sites, calcium
channels and synaptic vesicles, and the use of a calcium sensor for
release
with five low-affinity calcium-binding sites, lead to the generation
of a
burst of neurotransmitter release synchronous with the
stimulus1.
But neurons also secrete neurotransmitter through another, much less
well-understood mechanism called asynchronous release. On page
676of
this issue, Sun et
al. shed
light on asynchronous release, showing that it is mediated by an
unidentified calcium sensor with unexpected properties (...)

Nature 450, 676-682 (29 November 2007) | doi:10.1038/nature06308;

A dual-Ca2+-sensor model for neurotransmitter release in a central
synapse

Jianyuan Sun, Zhiping P.Pang, Dengkui Qin, Abigail T. Fahim, Roberto Adachi & Thomas C. Südhof
Abstract
Ca2+-triggered synchronous neurotransmitter release is well
described, but asynchronous release—in fact, its very
existence—remains
enigmatic. Here we report a quantitative description of asynchronous
neurotransmitter release in calyx-of-Held synapses. We show that
deletion of
synaptotagmin 2 (Syt2) in mice selectively abolishes synchronous
release,
allowing us to study pure asynchronous release in isolation (...)

[thanks to Malcolm Dean for calling my attention to this discovery – Alfredo]

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