When nerve cells stop speaking

By researching fruit flies, neuroscientists of the NeuroCure Cluster of Excellence in Berlin were able to gain a better understanding of a meaningful mechanism of neuronal communication. They demonstrated the importance of a specific protein for signal transmission between nerve cells. This is of high significance as certain people with autism – a functional development disturbances of the brain – suffer from genetic defects in this protein. Therefore the findings could improve the possibility of treating this disease more effectively. The results are presented in the latest issue of the professional journal Science.

When our brain is at work, for example when we are looking at a picture or planning a movement, its nerve cells communicate with each other. For this purpose they are equipped with specific points of contact, so called synapses. Both sides of a synapse are specialised and have a complex setup which makes sure that the transmission of information from an individual synapse is only ever possible in one direction. The sender – the presynaptic side – is filled with a neurotransmitter that is released in the direction of the recipient – the postsynaptic side – upon an electric command. Although this may sound simple, it is a highly complicated biochemical process that takes place in less than a millisecond and is strictly controlled in terms of space and time. A great number of specialised proteins are required to cooperate and enable an optimal release of the neurotransmitter. The “RIM binding protein” (RBP) plays an important part in this respect. As demonstrated by the scientists of the NeuroCure Cluster of Excellence surrounding Stephan Sigrist (Freie Universität Berlin) and Dietmar Schmitz (Charité – Universitätsmedizin Berlin and Deutsches Zentrum für Neurodegenerative Erkrankungen), the RBP-protein is of great significance for releasing the neurotransmitter.

The neuroscientists used the fruit fly as a model organism. Thanks to the simple setup of its brain and synapses it is ideal for experimental examinations. At the same time, the fly’s synaptic proteins are very similar to those of humans due to common descent dating back hundreds of million years ago. Through functional experiments and a new method of high-resolution microscopy, the scientists gained insights into previously unknown areas where the transmission takes place. The neuroscientists found out that the RBP-protein holds a key position in the fruit fly’s presynapsis. It is necessary for effectively connecting the release of the neurotransmitter to the electric command, which enables the sensible communication between nerve cells.

There are more and more indications that genetic defects in the RBP-proteins are an important aspect of autism in humans. The initial functional description of the fruit fly’s RBP-protein therefore does not only extend our comprehension of neuronal communication, it also provides a reference point to help understand brain malfunctions that occur with autism. For this reason the neuroscientists are hoping to contribute to the fundamental principles of a more effective treatment.

NeuroCure is a Cluster of Excellence in the framework of the Excellence Initiative funded by the German federal and state governments since 2007. The interdisciplinary research alliance crosslinks basic neuroscience research and clinical application to translate scientific findings on the functioning of the nervous system and neurological diseases to effective therapies.