Cell biologists discover crucial 鈥榯raffic regulator鈥 in neurons

Important for understanding neurodegenerative diseases

Cell biologists led by Utrecht 木瓜福利影视鈥檚 Professor Casper Hoogenraad have discovered the protein that may be the crucial traffic regulator for the transport of vital molecules inside nerve cells. When this traffic regulator is removed, the flow of traffic comes to a halt. The resulting 鈥榯raffic jams鈥 are reported to play a key role in neurodegenerative diseases such as Alzheimer and Parkinson鈥檚 disease. The discovery of this traffic regulator may therefore be crucial for a better understanding of the development of neural disorders. The results of their research will be published in the scientific journal Neuron on Wednesday 19 April.

Neurons are the main cells in the nervous system. They process information by sending, receiving, and combining signals from around the brain and the body. All neurons have a cell body where molecules vital for its functioning and maintenance are produced. The axon, a long and slender extension that can reach one metre in length in humans, sends information from the nerve cell to other nerve cells. Neuronal survival is highly dependent on the transport of vital molecules within this axon. Research has shown that defects in the transport function in the axons play a key role in degenerative brain diseases such as Alzheimer.

Artist impression of transport in a neuron (NastPlas TM)
Artist impression of transport in a neuron (NastPlas)

First comprehensive map

鈥淧revious research examined transport processes in small areas of the axon, such as the very beginning or the very end. This left it unclear how the movement of molecules through the axon was regulated over long distances. In our study, we provide the first comprehensive map of transport in mammalian axons鈥, says Casper Hoogenraad, Professor of Cell Biology at Utrecht 木瓜福利影视, explaining the relevance of this study.

Stumped

In most neurons, an area between the cell body and the axon called the 鈥榓xon initial segment鈥 serves as a checkpoint: only some molecules can pass through it. This area has stumped scientists for more than a decade. Why should one type of molecule be able to pass through this area, while others cannot? The answer is to be found in the traffic regulator, a protein called MAP2. 鈥淲ith this discovery, we have answered a fundamental question about the unique functioning of nerve cells that has occupied scientists for a long time鈥, lead author of the study Dr Laura Gumy says.

Driving force

The cell biologists from Utrecht first discovered that larger quantities of MAP2 accumulate between the cell body and the axon. When they removed MAP2 from the neuron, the normal pattern of molecule movement changed. Certain molecules suddenly ceased to enter the axon, whereas others accumulated in the axon instead of passing through to the cell body. This abnormal transport indicates that MAP2 is the driving force behind transport within the axon.

Car key

The cell biologists from Utrecht 木瓜福利影视 went on to make another very important discovery. Since axons are so long, transport in the neurons is carried out by sets of proteins 鈥 known as 鈥榤otor proteins鈥 鈥 that carry packages of other proteins on their back. As it turns out, MAP2 is able to switch a specific 鈥榤otor protein鈥 on or off, like a car key. This means that MAP2 actually controls which packages of molecules may enter the axon and which may not. Targeting the activity of the transport engine allowed the researchers to make another interesting discovery: MAP2 is also able to control the delivery of molecules at specific points along the axon.

    Casper Hoogenraad
    Prof. Casper Hoogenraad

    New targets for therapies

    鈥淭ransport within axons has been shown to fail in Alzheimer, Parkinson鈥檚 disease and Huntington鈥檚 disease, as well as in many other diseases. When the neuron is no longer able to control where molecules go, or is unable to get molecules to where they need to be, it cannot do its job. By understanding how transport works, we have laid the foundation for considering new targets and potential therapies for various neurodegenerative disorders鈥, Casper Hoogenraad concludes.

    Publication

    鈥楳AP2 defines a pre-axonal filtering zone to regulate KIF1-versus KIF5-dependent cargo transport in sensory neurons鈥

    Laura F. Gumy, Eugene A. Katrukha, Ilya Grigoriev, Dick Jaarsma, Lukas C. Kapitein, Anna Akhmanova, and Casper C. Hoogenraad

    Neuron 19 maart 2017, (downloadable after the embargo has lifted)

    More information

    • Visit the website of the Cell Biology group of Utrecht 木瓜福利影视
    • This research is part of Science for Life, one of the four themes of Utrecht 木瓜福利影视鈥檚 interdisciplinary research programme Life Sciences

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