Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

MDC Researchers Discover Molecule Responsible for Axonal Branching

21.09.2009
The human brain consists of about 100 billion (1011) neurons, which altogether form about 100 trillion (1014) synaptic connections with each other. A crucial mechanism for the generation of this complex wiring pattern is the formation of neuronal branches. The neurobiologists Dr. Hannes Schmidt and Professor Fritz G. Rathjen at the Max Delbrück Center for Molecular Medicine (MDC) Berlin-Buch, Germany, have now discovered a molecule that regulates this vital process. At the same time they have succeeded in elucidating the signaling cascade induced by this molecule (PNAS, Early Edition, 2009, doi:10.1073)*.

Through the ramification of its fiber-like axon, a single neuron can send branches and thus transmit information into several target areas at the same time. In principle, neurobiologists distinguish between two kinds of axonal branching: branching of the growth cone at the tip of an axon and the sprouting of collaterals (interstitial branching) from the axon shaft.

Both forms of axonal branching can be observed in sensory neurons, which transmit the sensation of touch, pain and temperature, among others. When the axons of these neurons reach the spinal cord, their growth cones first split (bifurcate) and consequently the axons divide into two branches growing in opposite directions. Later new branches sprout from the shaft of these daughter axons which penetrate the gray matter of the spinal cord.

Through investigations on sensory neurons, Dr. Hannes Schmidt and his colleagues were able to identify a protein which triggers the splitting of the growth cone of the sensory axons: the peptide CNP (the abbreviation stands for C-type natriuretic peptide). In transgenic mice the scientists were able to show that CNP is formed in the spinal cord precisely when sensory neurons grow into it. In the absence of CNP bifurcation can no longer occur which results in reduced neuronal connectivity in the spinal cord.

The new findings supplement earlier discoveries of the research group of Professor Rathjen according to which a cGMP-signaling cascade is responsible for the bifurcation of sensory axons. When CNP binds to its receptor Npr2 (natriuretic peptide receptor 2) on the surface of the axons, this signaling cascade is set in motion, which in turn induces the formation of the secondary messenger molecule cGMP. This messenger molecule then activates the protein kinase cGKI (cGMP-dependent protein kinase I), which can switch on and off a whole series of target proteins. The cytoskeleton of the neurons is thus altered in such a way that their growth cone splits into two daughter axons.

Next, the researchers want to identify these target proteins. Further analyses should clarify whether the cGMP signaling cascade likewise regulates the branching of other axon systems and whether this impacts the sensation of pain.

*C-type natriuretic peptide (CNP) is a bifurcation factor for sensory neurons
Author affiliation: Hannes Schmidta, Agne Stonkutea, René Jüttnera, Doris Koeslingb, Andreas Friebeb,c, Fritz G. Rathjena
a Department of Developmental Neurobiology, Max Delbrück Center for Molecular Medicine, Robert Rössle Str. 10, D-13092 Berlin
b Institute for Pharmacology and Toxicology, Ruhr University Bochum, D-44780 Bochum
c Present address: Institute for Physiology I, University of Würzburg, Röntgenring 9, D-97070 Würzburg

Correspondence to F.G. Rathjen: rathjen@mdc-berlin.de

Barbara Bachtler
Press and Public Affairs
Max Delbrück Center for Molecular Medicine (MDC) Berlin-Buch
Robert-Rössle-Straße 10
13125 Berlin, Germany
Phone: +49 (0) 30 94 06 - 38 96
Fax: +49 (0) 30 94 06 - 38 33
e-mail: presse@mdc-berlin.de

Barbara Bachtler | idw
Further information:
http://www.mdc-berlin.de/
http://www.mdc-berlin.de/en/research/research_teams/developmental_neurobiology/Projects/index.html

More articles from Life Sciences:

nachricht Nanoparticle Exposure Can Awaken Dormant Viruses in the Lungs
16.01.2017 | Helmholtz Zentrum München - Deutsches Forschungszentrum für Gesundheit und Umwelt

nachricht Cholera bacteria infect more effectively with a simple twist of shape
13.01.2017 | Princeton University

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Interfacial Superconductivity: Magnetic and superconducting order revealed simultaneously

Researchers from the University of Hamburg in Germany, in collaboration with colleagues from the University of Aarhus in Denmark, have synthesized a new superconducting material by growing a few layers of an antiferromagnetic transition-metal chalcogenide on a bismuth-based topological insulator, both being non-superconducting materials.

While superconductivity and magnetism are generally believed to be mutually exclusive, surprisingly, in this new material, superconducting correlations...

Im Focus: Studying fundamental particles in materials

Laser-driving of semimetals allows creating novel quasiparticle states within condensed matter systems and switching between different states on ultrafast time scales

Studying properties of fundamental particles in condensed matter systems is a promising approach to quantum field theory. Quasiparticles offer the opportunity...

Im Focus: Designing Architecture with Solar Building Envelopes

Among the general public, solar thermal energy is currently associated with dark blue, rectangular collectors on building roofs. Technologies are needed for aesthetically high quality architecture which offer the architect more room for manoeuvre when it comes to low- and plus-energy buildings. With the “ArKol” project, researchers at Fraunhofer ISE together with partners are currently developing two façade collectors for solar thermal energy generation, which permit a high degree of design flexibility: a strip collector for opaque façade sections and a solar thermal blind for transparent sections. The current state of the two developments will be presented at the BAU 2017 trade fair.

As part of the “ArKol – development of architecturally highly integrated façade collectors with heat pipes” project, Fraunhofer ISE together with its partners...

Im Focus: How to inflate a hardened concrete shell with a weight of 80 t

At TU Wien, an alternative for resource intensive formwork for the construction of concrete domes was developed. It is now used in a test dome for the Austrian Federal Railways Infrastructure (ÖBB Infrastruktur).

Concrete shells are efficient structures, but not very resource efficient. The formwork for the construction of concrete domes alone requires a high amount of...

Im Focus: Bacterial Pac Man molecule snaps at sugar

Many pathogens use certain sugar compounds from their host to help conceal themselves against the immune system. Scientists at the University of Bonn have now, in cooperation with researchers at the University of York in the United Kingdom, analyzed the dynamics of a bacterial molecule that is involved in this process. They demonstrate that the protein grabs onto the sugar molecule with a Pac Man-like chewing motion and holds it until it can be used. Their results could help design therapeutics that could make the protein poorer at grabbing and holding and hence compromise the pathogen in the host. The study has now been published in “Biophysical Journal”.

The cells of the mouth, nose and intestinal mucosa produce large quantities of a chemical called sialic acid. Many bacteria possess a special transport system...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

12V, 48V, high-voltage – trends in E/E automotive architecture

10.01.2017 | Event News

2nd Conference on Non-Textual Information on 10 and 11 May 2017 in Hannover

09.01.2017 | Event News

Nothing will happen without batteries making it happen!

05.01.2017 | Event News

 
Latest News

Water - as the underlying driver of the Earth’s carbon cycle

17.01.2017 | Earth Sciences

Interfacial Superconductivity: Magnetic and superconducting order revealed simultaneously

17.01.2017 | Materials Sciences

Smart homes will “LISTEN” to your voice

17.01.2017 | Architecture and Construction

VideoLinks
B2B-VideoLinks
More VideoLinks >>>