Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Helping neurons find their way

26.10.2009
Variations in the spatial distribution of cellular signaling molecules provide the information needed to steer neuron growth within the brain

As the brain develops, neuronal axons extend outward in search of other neurons, all the while receiving ‘directions’ from the extracellular environment in the form of chemical signals that indicate when and where these growing axons should turn.

For example, axons exposed to a gradient distribution of nerve growth factor (NGF) protein will automatically steer in the direction of highest NGF concentration.

“NGF is one of the most extensively studied molecules that direct axon elongation,” explains Hiroyuki Kamiguchi of the RIKEN Brain Science Institute in Wako. “However, it has remained unclear for a long time how axons change the direction of elongation in response to NGF.”

NGF-mediated turning is facilitated in part by the cellular signaling molecule inositol trisphosphate (IP3), which in turn governs the intracellular release of calcium ions—an essential component of NGF’s chemo-attractive action. By applying advanced methods for molecular-resolution live cell imaging, Kamiguchi and his colleagues have now gained valuable insights into how this process directs axonal guidance1.

The researchers cultured chick-derived neurons expressing a genetically encoded sensor that fluoresces at specific wavelengths in the presence of IP3, and then observed how individual neurons responded to an NGF gradient in the vicinity of the growth cone—the leading edge of a growing axon. They immediately noted the establishment of an asymmetric distribution of IP3 within the growth cone and an elevated signal on the growth cone side exposed to higher NGF levels; this is mirrored by a similarly uneven distribution of IP3-induced calcium release. This asymmetry correlates directly with axonal turning such that the growth cone steers in the direction established by the highest levels of NGF, IP3 and calcium ion (Ca2+) release.

The development of techniques for accurately detecting potentially subtle variations in IP3 distribution was a key component of their success in this work. “We needed to detect 1% differences in fluorescence emission from the IP3 sensor between both sides of the growth cone,” says Kamiguchi.

However, he considers even the mere existence of such a gradient across the 10–20 micron width of the growth cone to be fairly surprising. “Because IP3 diffuses so rapidly in cytoplasm, it has not been viewed as a highly localized messenger,” he says. “This suggests the existence of robust degradation machinery to localize IP3 signals to one side of the growth cone.”

These insights into how neurons establish direction-specific signaling profiles should provide helpful starting points for understanding other models of cell polarization and migration.

The corresponding author for this highlight is based at the Laboratory for Neuronal Growth Mechanisms, RIKEN Brain Science Institute.

Saeko Okada | Research asia research news
Further information:
http://www.rikenresearch.riken.jp/eng/research/6060
http://www.researchsea.com

More articles from Life Sciences:

nachricht How gut bacteria can make us ill
18.01.2017 | Helmholtz-Zentrum für Infektionsforschung

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

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: How gut bacteria can make us ill

HZI researchers decipher infection mechanisms of Yersinia and immune responses of the host

Yersiniae cause severe intestinal infections. Studies using Yersinia pseudotuberculosis as a model organism aim to elucidate the infection mechanisms of these...

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...

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

How gut bacteria can make us ill

18.01.2017 | Life Sciences

On track to heal leukaemia

18.01.2017 | Health and Medicine

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

17.01.2017 | Earth Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>