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 Link Discovered between Immune System, Brain Structure and Memory
26.04.2017 | Universität Basel

nachricht Researchers develop eco-friendly, 4-in-1 catalyst
25.04.2017 | Brown 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: Making lightweight construction suitable for series production

More and more automobile companies are focusing on body parts made of carbon fiber reinforced plastics (CFRP). However, manufacturing and repair costs must be further reduced in order to make CFRP more economical in use. Together with the Volkswagen AG and five other partners in the project HolQueSt 3D, the Laser Zentrum Hannover e.V. (LZH) has developed laser processes for the automatic trimming, drilling and repair of three-dimensional components.

Automated manufacturing processes are the basis for ultimately establishing the series production of CFRP components. In the project HolQueSt 3D, the LZH has...

Im Focus: Wonder material? Novel nanotube structure strengthens thin films for flexible electronics

Reflecting the structure of composites found in nature and the ancient world, researchers at the University of Illinois at Urbana-Champaign have synthesized thin carbon nanotube (CNT) textiles that exhibit both high electrical conductivity and a level of toughness that is about fifty times higher than copper films, currently used in electronics.

"The structural robustness of thin metal films has significant importance for the reliable operation of smart skin and flexible electronics including...

Im Focus: Deep inside Galaxy M87

The nearby, giant radio galaxy M87 hosts a supermassive black hole (BH) and is well-known for its bright jet dominating the spectrum over ten orders of magnitude in frequency. Due to its proximity, jet prominence, and the large black hole mass, M87 is the best laboratory for investigating the formation, acceleration, and collimation of relativistic jets. A research team led by Silke Britzen from the Max Planck Institute for Radio Astronomy in Bonn, Germany, has found strong indication for turbulent processes connecting the accretion disk and the jet of that galaxy providing insights into the longstanding problem of the origin of astrophysical jets.

Supermassive black holes form some of the most enigmatic phenomena in astrophysics. Their enormous energy output is supposed to be generated by the...

Im Focus: A Quantum Low Pass for Photons

Physicists in Garching observe novel quantum effect that limits the number of emitted photons.

The probability to find a certain number of photons inside a laser pulse usually corresponds to a classical distribution of independent events, the so-called...

Im Focus: Microprocessors based on a layer of just three atoms

Microprocessors based on atomically thin materials hold the promise of the evolution of traditional processors as well as new applications in the field of flexible electronics. Now, a TU Wien research team led by Thomas Müller has made a breakthrough in this field as part of an ongoing research project.

Two-dimensional materials, or 2D materials for short, are extremely versatile, although – or often more precisely because – they are made up of just one or a...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Expert meeting “Health Business Connect” will connect international medical technology companies

20.04.2017 | Event News

Wenn der Computer das Gehirn austrickst

18.04.2017 | Event News

7th International Conference on Crystalline Silicon Photovoltaics in Freiburg on April 3-5, 2017

03.04.2017 | Event News

 
Latest News

Scientist invents way to trigger artificial photosynthesis to clean air

26.04.2017 | Materials Sciences

Ammonium nitrogen input increases the synthesis of anticarcinogenic compounds in broccoli

26.04.2017 | Agricultural and Forestry Science

SwRI-led team discovers lull in Mars' giant impact history

26.04.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>