These small gaps between nerve cell endings have to be just the right size for messages to transmit properly. Synapses that grow too large or too small are associated with motor and cognitive impairment, learning and memory difficulties, and other neurological disorders.
In a finding that sheds light on this system, researchers at the University of Wisconsin-Madison describe a gene that controls the proper development of synapses, which could help explain how the process works and why it sometimes goes wrong.
Reporting today in the journal Neuron, a team of geneticists in the College of Agricultural and Life Sciences reveal the role of a gene in fruit flies called "nervous wreck" that prevents synapses from overgrowing by damping the effects of a pro-growth signal. Mutations in a human version of "nervous wreck" have been linked to a severe genetic developmental disability, and these findings may eventually help scientists develop treatments for this and other neurological disorders.
"The precise regulation of synaptic growth - not too much and not too little - is a complex biological process," says Kate O'Connor-Giles, a postdoctoral fellow in the genetics department who led the study. "We really need to have a deep understanding of how all the factors involved are working together to develop rational treatments for neurological disorders associated with aberrant synaptic growth."
That's no small task. The brain is the most complex organ in the body, containing a hundred billion nerve cells that branch out and make trillions of connections to other neurons, muscle cells and other cell types. Although an estimated 50 million Americans have some kind of neurological disorder, in the majority of cases the underlying cause is unknown. Improper synaptic growth may explain a portion of these unknown cases.
To crack this complex system, O'Connor-Giles studies a particular type of synapse in fruit flies, known as the neuromuscular junction, which is relatively easy to examine and closely resembles the synapses found in the central nervous system of humans. She works with a particular kind of fly that is unable to produce functional Nervous wreck protein, one of a collection of mutant flies engineered more than 20 years ago by UW-Madison geneticist Barry Ganetzky, in whose laboratory the study was completed with the help of researcher Ling Ling Ho. This collection has been the source of many seminal discoveries in brain science over the years.
Using genetic, biochemical and imaging techniques, O'Connor-Giles showed that the "nervous wreck" protein appears to be part of an important protein complex that helps regulate the density of certain receptors on the surface of the nerve cell at the synapse. In particular, the new findings suggest that the protein complex decommissions receptors that respond to pro-growth signals coming from the well-studied BMP signaling pathway. When the protein complex is working properly, it moves the receptors back inside the nerve cell - where they can no longer receive and respond to the pro-growth signal - at the appropriate time.
"'Nervous wreck' and (the other proteins in the complex) work together to attenuate a positive growth signal," says O'Connor-Giles. "So when it's time for synaptic growth to stop, they are the proteins that ensure the neuron stops listening to the positive growth signal and stops growing.
When 'nervous wreck' is absent, you get synapses that are much too large." Problems with other proteins in the complex also lead to synaptic overgrowth in fruit flies and, O'Connor-Giles predicts, may contribute to developmental disabilities in humans as well.
Although her work was done in synapses undergoing initial formation, these findings likely apply to adult brain cells, too. Inside fully formed brains, neural connections grow and change over time in response to experiences, a process called plasticity.
"The presumption is that the same mechanisms that are at play during the initial formation of synapses are then recruited later in life when these synapses need to be modified in response to experience or injury," says O'Connor-Giles. "So by understanding the initial development of synapses, we may also be getting at the molecular mechanisms underlying plasticity."
These findings add to the big picture of how synaptic growth works, a picture that in the long run will help scientists develop treatments for various neurological disorders.
"Being able to manipulate synaptic growth is going to be crucial for treating traumatic spinal chord injuries," says O'Connor-Giles. "It's also going to be important for treating a broad array of other disorders, including epilepsy and developmental disabilities."
Kate O'Connor-Giles | EurekAlert!
Symbiotic bacteria: from hitchhiker to beetle bodyguard
28.04.2017 | Johannes Gutenberg-Universität Mainz
Nose2Brain – Better Therapy for Multiple Sclerosis
28.04.2017 | Fraunhofer-Institut für Grenzflächen- und Bioverfahrenstechnik IGB
More and more automobile companies are focusing on body parts made of carbon fiber reinforced plastics (CFRP). However, manufacturing and repair costs must be further reduced in order to make CFRP more economical in use. Together with the Volkswagen AG and five other partners in the project HolQueSt 3D, the Laser Zentrum Hannover e.V. (LZH) has developed laser processes for the automatic trimming, drilling and repair of three-dimensional components.
Automated manufacturing processes are the basis for ultimately establishing the series production of CFRP components. In the project HolQueSt 3D, the LZH has...
Reflecting the structure of composites found in nature and the ancient world, researchers at the University of Illinois at Urbana-Champaign have synthesized thin carbon nanotube (CNT) textiles that exhibit both high electrical conductivity and a level of toughness that is about fifty times higher than copper films, currently used in electronics.
"The structural robustness of thin metal films has significant importance for the reliable operation of smart skin and flexible electronics including...
The nearby, giant radio galaxy M87 hosts a supermassive black hole (BH) and is well-known for its bright jet dominating the spectrum over ten orders of magnitude in frequency. Due to its proximity, jet prominence, and the large black hole mass, M87 is the best laboratory for investigating the formation, acceleration, and collimation of relativistic jets. A research team led by Silke Britzen from the Max Planck Institute for Radio Astronomy in Bonn, Germany, has found strong indication for turbulent processes connecting the accretion disk and the jet of that galaxy providing insights into the longstanding problem of the origin of astrophysical jets.
Supermassive black holes form some of the most enigmatic phenomena in astrophysics. Their enormous energy output is supposed to be generated by the...
The probability to find a certain number of photons inside a laser pulse usually corresponds to a classical distribution of independent events, the so-called...
Microprocessors based on atomically thin materials hold the promise of the evolution of traditional processors as well as new applications in the field of flexible electronics. Now, a TU Wien research team led by Thomas Müller has made a breakthrough in this field as part of an ongoing research project.
Two-dimensional materials, or 2D materials for short, are extremely versatile, although – or often more precisely because – they are made up of just one or a...
28.04.2017 | Event News
20.04.2017 | Event News
18.04.2017 | Event News
28.04.2017 | Medical Engineering
28.04.2017 | Earth Sciences
28.04.2017 | Life Sciences