Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Researchers find molecule that inhibits regrowth of spinal nerve cells

12.07.2005


A molecule that helps the body’s motor nerve cells grow along proper paths during embryonic development also plays a major role in inhibiting spinal-cord neurons from regenerating after injury, researchers at UT Southwestern Medical Center have found. In cultured cells, the researchers found that a component of myelin – a substance that normally insulates and stabilizes long nerve fibers in adult vertebrates – chemically blocks the ability of nerve cells to grow through myelin that is released when the spinal cord is damaged. While other myelin components also block nerve growth, a component called ephrin-B3 inhibits such activity as well or better than that of other known blocking agents combined, UT Southwestern researchers report in an upcoming issue of the Proceedings of the National Academy of Sciences.



"I believe that to the extent that overcoming myelin-based inhibition is going to provide some sort of functional recovery for spinal cord injury patients, understanding ephrins is a major step forward," said Dr. Luis Parada, senior author on the paper and director of the Center for Developmental Biology and the Kent Waldrep Center for Basic Research on Nerve Growth and Regeneration at UT Southwestern. A mixture of molecules and proteins, myelin insulates nerve fibers and impedes them from having contact with other nerve cells. After a spinal-cord injury, myelin is released into the tissues. Not only does myelin encourage the growth of scars – called glial scars – which physically block nerve cells from regrowing in the damaged area, but components of myelin also chemically prevent nerve cells from regrowing there as well.

Considerable research has been done in the past 10 years to identify elements in myelin that chemically inhibit the regeneration of nerve cells, Dr. Parada said. Three individual components – the molecules Nogo, MAG and OMgp – have been shown to do so in isolation. Developmental biologists at UT Southwestern have been studying how ephrin-B3 helps control how and where nerve fibers grow during early development. They previously showed that the molecule throws up "fences" that repel developing nerves and guide them along the pathways to their appropriate connections to muscles.


In 2002 Dr. Mark Henkemeyer, associate professor in the Center for Developmental Biology and of cell biology and one of the authors of the PNAS study, found that such a "fence" is erected specifically down the middle of the cortical spinal tract, which is damaged during spinal-cord injury.

In the current study, Dr. Parada and his colleagues asked: What is this molecule, whose normal function is to be repellent during embryonic development, doing in the mature system?

"To our surprise, we found that ephrin-B3, which normally is present as a ’wall’ down the middle of adult spinal cords, also is found in very high levels in adult myelin," said Dr. Parada.

The researchers knew from previous work that ephrin-B3 interacts with receptors on neurons in the cortical spinal cord. So, in the lab, led by the study’s lead author Dr. M. Douglas Benson, a postdoctoral research fellow, they cultured neurons together with isolated ephrin-B3 and confirmed that the molecule activated the neuron’s receptors. They then cultured normal myelin together with the neurons and got the same results.

However, when they cultured neurons with myelin from which the ephrin-B3 had been removed, the receptors were not activated. The findings suggest that there is much more to be learned about myelin-based inhibition, Dr. Parada said. "We firmly believe that ephrin-B3 is an important, functional, relevant component of myelin, although there may be other elements that are left to be discovered," he said.

Dr. Parada added that several factors must be overcome before spinal-cord regeneration and recovery from injury can occur in a meaningful way for patients.

"We have to figure out how to dissolve the glial scars or impede their formation," he said. "We also need to get mature neurons to be better at growing, similar to the way they do during embryonic development. And finally, we have to remove myelin-based inhibition. If and when we achieve those three things, then we’ll have robust regeneration of injured nerves."

Other Center for Developmental Biology researchers involved with the study were Dr. Mark Lush, postdoctoral research fellow, and Dr. Q. Richard Lu, assistant professor. Dr. Mario Romero, assistant professor of neurology, also contributed.

Amanda Siegfried | EurekAlert!
Further information:
http://www.utsouthwestern.edu

More articles from Life Sciences:

nachricht New RNA sequencing strategy provides insight into microbiomes
17.12.2018 | University of Chicago Medical Center

nachricht Mass spectrometry sheds new light on thallium poisoning cold case
14.12.2018 | University of Maryland

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Data storage using individual molecules

Researchers from the University of Basel have reported a new method that allows the physical state of just a few atoms or molecules within a network to be controlled. It is based on the spontaneous self-organization of molecules into extensive networks with pores about one nanometer in size. In the journal ‘small’, the physicists reported on their investigations, which could be of particular importance for the development of new storage devices.

Around the world, researchers are attempting to shrink data storage devices to achieve as large a storage capacity in as small a space as possible. In almost...

Im Focus: Data use draining your battery? Tiny device to speed up memory while also saving power

The more objects we make "smart," from watches to entire buildings, the greater the need for these devices to store and retrieve massive amounts of data quickly without consuming too much power.

Millions of new memory cells could be part of a computer chip and provide that speed and energy savings, thanks to the discovery of a previously unobserved...

Im Focus: An energy-efficient way to stay warm: Sew high-tech heating patches to your clothes

Personal patches could reduce energy waste in buildings, Rutgers-led study says

What if, instead of turning up the thermostat, you could warm up with high-tech, flexible patches sewn into your clothes - while significantly reducing your...

Im Focus: Lethal combination: Drug cocktail turns off the juice to cancer cells

A widely used diabetes medication combined with an antihypertensive drug specifically inhibits tumor growth – this was discovered by researchers from the University of Basel’s Biozentrum two years ago. In a follow-up study, recently published in “Cell Reports”, the scientists report that this drug cocktail induces cancer cell death by switching off their energy supply.

The widely used anti-diabetes drug metformin not only reduces blood sugar but also has an anti-cancer effect. However, the metformin dose commonly used in the...

Im Focus: New Foldable Drone Flies through Narrow Holes in Rescue Missions

A research team from the University of Zurich has developed a new drone that can retract its propeller arms in flight and make itself small to fit through narrow gaps and holes. This is particularly useful when searching for victims of natural disasters.

Inspecting a damaged building after an earthquake or during a fire is exactly the kind of job that human rescuers would like drones to do for them. A flying...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

ICTM Conference 2019: Digitization emerges as an engineering trend for turbomachinery construction

12.12.2018 | Event News

New Plastics Economy Investor Forum - Meeting Point for Innovations

10.12.2018 | Event News

EGU 2019 meeting: Media registration now open

06.12.2018 | Event News

 
Latest News

Formed to Meet Customers’ Needs – New Laser Beams for Glass Processing

17.12.2018 | Physics and Astronomy

Preserving soil quality in the long term

17.12.2018 | Architecture and Construction

New RNA sequencing strategy provides insight into microbiomes

17.12.2018 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>