Navigation Links
Loose coupling between calcium channels and sensors

This news release is available in German.

Information transmission at the synapse between neurons is a highly complex, but at the same time very fast, series of events. When a voltage change, the so-called action potential, reaches the synaptic terminal in the presynaptic neuron, calcium flows through voltage-gated calcium channels into the presynaptic neuron. This influx leads to a rise in the intracellular calcium concentration. Calcium then binds to a calcium sensor in the presynaptic terminal, which in turn triggers the release of vesicles containing neurotransmitters into the synapse. The released neurotransmitter binds to postsynaptic receptors, leading to a response in the postsynaptic neuron. The coupling between calcium channels and sensors of exocytosis is key in determining the speed, timing and probability of synaptic transmission. Two forms of coupling occur in the brain: in tight, or nanodomain" coupling, channels and sensors are located very close to each other, with 10 to 20 nm distance, while in loose, or microdomain" coupling, channel and sensor are further apart, in the region of around 100 nm. Previous research suggests that loose coupling occurs in synapses during early development, while tight coupling is observed in the mature central nervous system. In their current paper, Vyleta and Jonas ask whether, given the advantages of tight coupling including the speed, temporal precision, fidelity and energy efficiency of synaptic transmission any synapse in the mature central nervous system makes use of loose coupling? And if it does so, what are the consequences for the function of synaptic transmission?

A specific synapse in the hippocampus, the mossy fiber synapse on CA3 pyramidal neurons, which is accessible to direct recording using the patch-clamp method and shows a high degree of plasticity, was the focus in this research (Figure). To investigate whether loose or tight coupling occurs in this synapse, Vyleta and Jonas made use of calcium chelators, which capture calcium ions on their way from the source to the sensor, to investigate the timescale and distance of coupling. If only the fast-acting chelator, BAPTA, can inhibit exocytosis and synaptic transmission, but the slow chelator EGTA cannot, tight coupling is at work, while in loose coupling, both fast and slow chelators can inhibit transmission. As both fast and slow chelators suppress transmission in the synapse under investigation, results suggest loose coupling between channels and sensors, with a mean coupling distance of around 75 nm.

Why does loose coupling, which is likely slower and has less fidelity than tight coupling, exist in the mossy fiber-pyramidal neuron synapse? Further results by Vyleta and Jonas show that due to loose coupling, fast endogenous calcium buffers in the synapse can act as a brake on transmission, controlling how likely the initial release of neurotransmitter is. Loose coupling provides the time frame for endogenous buffers to act on synaptic transmission. The saturation of endogenous buffers after repeated stimulation may also promote facilitation, the phenomenon in which impulses are more likely to generate action potentials when they closely follow a prior impulse.

The new findings challenge the view that loose coupling is a developmental phenomenon, demonstrating instead that coupling is regulated in a synapse-specific way. Loose coupling is predominantly used at dynamic and plastic synapses, both in the developing and the mature brain. Together with fast endogenous calcium buffers, loose channel-sensor coupling may provide the molecular framework for presynaptic plasticity, a hallmark of hippocampal neurons.


Contact: Oliver Lehmann
Institute of Science and Technology Austria

Related biology news :

1. Natural selection enables purple loosestrife to invade northern Ontario
2. Dolphins cultivate loose alliances
3. Telecoupling science shows Chinas forest sustainability packs global impact
4. Telecoupling pulls pieces of sustainability puzzle together
5. Price Family Foundation funds research collaboration between Albert Einstein College of Medicine and University of Oklahoma
6. New study finds differences in concussion risk between football helmets
7. New study reveals links between alcoholic liver disease and the circadian clock
8. Researchers discover that coevolution between humans and bacteria reduces gastric cancer risk
9. Research uncovers key difference between our bodies fight against viruses and bacteria
10. New research: Effects of eating half an avocado with lunch on satiety & desire to eat between meals
11. Eurofins scientists discover genetic differences between identical twins
Post Your Comments:
Related Image:
Loose coupling between calcium channels and sensors
(Date:11/17/2015)... , November 17, 2015 ... au 19 novembre  2015.  --> Paris ... --> DERMALOG, le leader de l,innovation biométrique, ... la fois passeports et empreintes sur la même surface ... les passeports et l,autre pour les empreintes digitales. Désormais, ...
(Date:11/16/2015)... Nov 16, 2015  Synaptics Inc. (NASDAQ: ... solutions, today announced expansion of its TDDI product ... touch controller and display driver integration (TDDI) solutions ... These new TDDI products add to the previously-announced ... TD4302 (WQHD resolution), and TD4322 (FHD resolution) solutions. ...
(Date:11/12/2015)... 11, 2015   Growing need for low-cost, ... has been paving the way for use of ... discrete analytes in clinical, agricultural, environmental, food and ... used in medical applications, however, their adoption is ... to continuous emphasis on improving product quality and ...
Breaking Biology News(10 mins):
(Date:12/1/2015)... Dec. 1, 2015 Frost & Sullivan ... This program addresses ways companies can innovate and ... --> ... --> ... as well as the disrupting factors altering the ...
(Date:12/1/2015)... ... December 01, 2015 , ... Park Systems , world ... scanning ion conductance microscopy module to Park NX10 that is the only product ... SICM benefits virtually all materials characterization that require measurements in liquid such as ...
(Date:12/1/2015)... December 1, 2015 Dr. Harry Lander , President of ... as Chief Science Officer and recruits five distinguished ... Lander , President of Regen, expands his role to include ... recruits five distinguished scientists to join advisory team ... expands his role to include serving as ...
(Date:11/30/2015)... (PRWEB) , ... November 30, 2015 , ... Global ... and development stages of a new closed system for isolating adipose-derived stem cells. The ... vascular fraction (SVF) of adipose tissue. SVF is a component of the lipoaspirate obtained ...
Breaking Biology Technology: