Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

How nerve cells grow

19.02.2010
Göttingen-based Max Planck researcher decodes a molecular process that controls the growth of nerve cells

Brain researcher Hiroshi Kawabe has discovered the workings of a process that had been completely overlooked until now, and that allows nerve cells in the brain to grow and form complex networks. The study, which has now been published in the journal Neuron, shows that an enzyme which usually controls the destruction of protein components has an unexpected function in nerve cells: it controls the structure of the cytoskeleton and thus ensures that nerve cells can form the tree-like extensions that are necessary for signal transmission in the brain. (Neuron, February 11, 2010)


In the brain of mice, which cannot produce Nedd4-1, the extensions of nerve cells are shorter and of much simpler construction (example top) than in the brain of normal mice (example bottom). Image: Hiroshi Kawabe

In order to be able to receive signals from other cells, nerve cells form complex extensions called dendrites (from the Greek ‘dendron’ meaning tree). The growth of dendrites in the human brain takes place mainly during late embryonic and infantile brain development. During this phase, dendrites, with a total length of many hundred kilometres, grow from the 100 billion nerve cells in our brain. The result is a highly-complex network of nerve cells that controls all bodily functions - from breathing to complicated learning processes.

In order that this incredible growth phase of brain development does not lead to chaos, the growth of the dendrites must be accurately controlled. In fact, a large number of signal processes control the direction and the speed of dendrite growth by influencing the structure of the cytoskeleton, which is inside the growing dendrite and responsible for its shape and extension.

The Göttingen-based brain researcher Hiroshi Kawabe has now discovered exactly how the growth of the cytoskeleton is controlled during the dendrite development. Using specially bred genetically engineered mice, the Japanese guest scientist, who conducts research at the Max Planck Institute for Experimental Medicine, discovered that the Nedd4-1 enzyme is essential for regular dendrite growth. Nedd4-1 is an enzyme that usually controls the degradation of protein components in cells by combining them with another protein called ubiquitin. The cell identifies these ubiquitinated molecules as "waste" and degrades them. In some cases, however, the ubiquitination does not lead to the degradation of the marked protein but changes its function instead.

Nedd4-1 prevents degradation of the cytoskeleton

Hiroshi Kawabe has now shown that the Nedd4-1 enzyme ubiquitinates a signal protein called Rap2, and thus prevents it causing the dismemberment of the cytoskeleton and the collapse of the dendrites. "As long as Nedd4-1 is active, the nerve cell dendrites can grow normally," reports Kawabe. "In its absence, the dendrite growth comes to a standstill and previously formed dendrites collapse, with dramatic consequences for the function of nerve cell networks in the brain." There are, however, probably a number of parallel operating signal paths which control the dendrite growth. This explains why nerve cells can also form dendrites without Nedd4-1 - albeit significantly fewer in number and shorter. The Nedd4/Rap2/TNIK mechanism would then be only one of several that can partially compensate each other.

Kawabe's discovery provides important new insight into the mechanisms which control the development of the brain. "What is surprising is that no-one has investigated this before," says the Japanese biochemist. Scientists have long been aware that Nedd4-1 is one of the most prevalent ubiquitination enzymes in nerve cells and is produced with great frequency in the developmental phase when nerve cells grow and form their dendrites. As Kawabe points out, the function of Nedd4-1 has already been investigated in dozens of studies. "But very little work has been carried out on its role in nerve cell development, which would have been the obvious thing to do."

Original work:

Kawabe, H., Neeb, A., Dimova, K., Young, S.M.Jr. Takeda, M., Katsurabayashi, S., Mitkovski, M., Malakhova, O.A., Zhang, D.-E., Umikawa, M., Kariya, K., Goebbels, S., Nave, K.-A., Rosenmund, C., Jahn, O., Rhee, J.-S. and Brose, N.
Regulation of Rap2A by the ubiquitin ligase Nedd4-1 controls neurite development in cortical neurons.

Neuron 65, 358-372 (2010)

Contact:

Dr. Hiroshi Kawabe
Max-Planck-Institute for Experimental Medicine, Göttingen
Tel.: +49 (0)551 / 3899 720
E-mail: kawabe@em.mpg.de

Barbara Abrell | EurekAlert!
Further information:
http://www.mpg.de/english/

More articles from Life Sciences:

nachricht Warming ponds could accelerate climate change
21.02.2017 | University of Exeter

nachricht An alternative to opioids? Compound from marine snail is potent pain reliever
21.02.2017 | University of Utah

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Breakthrough with a chain of gold atoms

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

Im Focus: DNA repair: a new letter in the cell alphabet

Results reveal how discoveries may be hidden in scientific “blind spots”

Cells need to repair damaged DNA in our genes to prevent the development of cancer and other diseases. Our cells therefore activate and send “repair-proteins”...

Im Focus: Dresdner scientists print tomorrow’s world

The Fraunhofer IWS Dresden and Technische Universität Dresden inaugurated their jointly operated Center for Additive Manufacturing Dresden (AMCD) with a festive ceremony on February 7, 2017. Scientists from various disciplines perform research on materials, additive manufacturing processes and innovative technologies, which build up components in a layer by layer process. This technology opens up new horizons for component design and combinations of functions. For example during fabrication, electrical conductors and sensors are already able to be additively manufactured into components. They provide information about stress conditions of a product during operation.

The 3D-printing technology, or additive manufacturing as it is often called, has long made the step out of scientific research laboratories into industrial...

Im Focus: Mimicking nature's cellular architectures via 3-D printing

Research offers new level of control over the structure of 3-D printed materials

Nature does amazing things with limited design materials. Grass, for example, can support its own weight, resist strong wind loads, and recover after being...

Im Focus: Three Magnetic States for Each Hole

Nanometer-scale magnetic perforated grids could create new possibilities for computing. Together with international colleagues, scientists from the Helmholtz Zentrum Dresden-Rossendorf (HZDR) have shown how a cobalt grid can be reliably programmed at room temperature. In addition they discovered that for every hole ("antidot") three magnetic states can be configured. The results have been published in the journal "Scientific Reports".

Physicist Dr. Rantej Bali from the HZDR, together with scientists from Singapore and Australia, designed a special grid structure in a thin layer of cobalt in...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Booth and panel discussion – The Lindau Nobel Laureate Meetings at the AAAS 2017 Annual Meeting

13.02.2017 | Event News

Complex Loading versus Hidden Reserves

10.02.2017 | Event News

International Conference on Crystal Growth in Freiburg

09.02.2017 | Event News

 
Latest News

Impacts of mass coral die-off on Indian Ocean reefs revealed

21.02.2017 | Earth Sciences

Novel breast tomosynthesis technique reduces screening recall rate

21.02.2017 | Medical Engineering

Use your Voice – and Smart Homes will “LISTEN”

21.02.2017 | Trade Fair News

VideoLinks
B2B-VideoLinks
More VideoLinks >>>