Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:


New growth-stimulating cue identified for nerve cells


Bathed in nutrients, but in the absence of any particular cue, axons will extend from cortex nerve cells in all directions (top image). Toss in a growth stimulator like semaphorin-7a, and axon growth is heavier nearest the cue (bottom image). Credit: Johns Hopkins Medical Institutions, Nature.

For decades, scientists have hunted for signals that guide nerve cells’ tentacle-like axons, hoping to understand how these cell tips reach out to distant targets. It’s knowledge that might one day help researchers learn how to rebuild nerves lost to spinal cord injuries or diseases like Huntington’s.

Now, a Johns Hopkins team studying a family of proteins best known for repelling axons and inhibiting their growth reports finding one member that unexpectedly promotes axon growth instead. In their experiments, rat nerves in the lab grew more and longer axons on the side nearest a source of this protein, called semaphorin-7a. Moreover, in mice without semaphorin-7a, axons of some odor-sensing nerve cells never reached their targets, the scientists report in the July 24 issue of Nature.

"I’ve been studying semaphorins for about a decade and didn’t expect to find any that stimulated axon growth, certainly not to the extent we saw in the lab and in mice," says Alex Kolodkin, Ph.D., professor of neuroscience in The Johns Hopkins University School of Medicine’s Institute for Basic Biomedical Sciences. "Now we need to figure out how semaphorins balance their repulsive and attractive effects."

Part of the answer to this paradox, Kolodkin says, is that semaphorin-7a interacts with different proteins than its relatives. In experiments with rat nerve cells involved in sensing odors, first author and postdoctoral fellow Jeroen Pasterkamp, Ph.D., found that semaphorin-7a spurs axon growth by hooking onto proteins called integrins, which are found on nerves and many other cell types.

Among their many roles, integrins (pronounced IN-teh-grins) help control cells’ interactions with their surroundings by capturing chemical signals and conveying the messages to cells’ internal machinery. Even though this is the first report to link semaphorins and integrins, both protein families are rapidly being recognized as major contributors to neurological function and disease, says Kolodkin.

"Because integrins are important throughout the body, targeting them to stimulate axon growth or re-growth in a particular area of the brain or spinal cord presents many problems," notes Pasterkamp. "Our next steps are to find out exactly how semaphorin-7a’s message is passed along inside the nerve, which will hopefully reveal a useful, specific target for promoting axon growth following nerve injury or degeneration."

As the researchers learn more of the specifics about how semaphorin-7a differs from its relatives, they also hope to redraw their picture of how semaphorins as a family affect nerve development throughout life, they say.

Joanna Downer | EurekAlert!
Further information:

More articles from Life Sciences:

nachricht Biologists unravel another mystery of what makes DNA go 'loopy'
16.03.2018 | Emory Health Sciences

nachricht Scientists map the portal to the cell's nucleus
16.03.2018 | Rockefeller 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: Locomotion control with photopigments

Researchers from Göttingen University discover additional function of opsins

Animal photoreceptors capture light with photopigments. Researchers from the University of Göttingen have now discovered that these photopigments fulfill an...

Im Focus: Surveying the Arctic: Tracking down carbon particles

Researchers embark on aerial campaign over Northeast Greenland

On 15 March, the AWI research aeroplane Polar 5 will depart for Greenland. Concentrating on the furthest northeast region of the island, an international team...

Im Focus: Unique Insights into the Antarctic Ice Shelf System

Data collected on ocean-ice interactions in the little-researched regions of the far south

The world’s second-largest ice shelf was the destination for a Polarstern expedition that ended in Punta Arenas, Chile on 14th March 2018. Oceanographers from...

Im Focus: ILA 2018: Laser alternative to hexavalent chromium coating

At the 2018 ILA Berlin Air Show from April 25–29, the Fraunhofer Institute for Laser Technology ILT is showcasing extreme high-speed Laser Material Deposition (EHLA): A video documents how for metal components that are highly loaded, EHLA has already proved itself as an alternative to hard chrome plating, which is now allowed only under special conditions.

When the EU restricted the use of hexavalent chromium compounds to special applications requiring authorization, the move prompted a rethink in the surface...

Im Focus: Radar for navigation support from autonomous flying drones

At the ILA Berlin, hall 4, booth 202, Fraunhofer FHR will present two radar sensors for navigation support of drones. The sensors are valuable components in the implementation of autonomous flying drones: they function as obstacle detectors to prevent collisions. Radar sensors also operate reliably in restricted visibility, e.g. in foggy or dusty conditions. Due to their ability to measure distances with high precision, the radar sensors can also be used as altimeters when other sources of information such as barometers or GPS are not available or cannot operate optimally.

Drones play an increasingly important role in the area of logistics and services. Well-known logistic companies place great hope in these compact, aerial...

All Focus news of the innovation-report >>>



Industry & Economy
Event News

Ultrafast Wireless and Chip Design at the DATE Conference in Dresden

16.03.2018 | Event News

International Tinnitus Conference of the Tinnitus Research Initiative in Regensburg

13.03.2018 | Event News

International Virtual Reality Conference “IEEE VR 2018” comes to Reutlingen, Germany

08.03.2018 | Event News

Latest News

Wandering greenhouse gas

16.03.2018 | Earth Sciences

'Frequency combs' ID chemicals within the mid-infrared spectral region

16.03.2018 | Physics and Astronomy

Biologists unravel another mystery of what makes DNA go 'loopy'

16.03.2018 | Life Sciences

Science & Research
Overview of more VideoLinks >>>