Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Structure-building cell signals also may influence learning, memory

11.04.2005


Ephrins may influence learning



A Burnham Institute study has found that one of the cell’s largest families of signaling molecules, called ephrins, which are known to regulate the development of nerve cells, also controls nerve cells’ ability to engulf critical chemicals and proteins for learning and memory. These findings, the first to link these molecular semaphores to this important nerve cell function, appear in the May issue of Nature Cell Biology, published in advance at the journal’s website on April 10th.

While the study’s results are not immediately applicable to treating disease, they pave the way for future experiments on the roles played by ephrins in memory, learning, and other nerve cell functions, and potentially even in certain cancers.


By inserting chicken ephrin genes into rat cells, Fumitoshi Irie, Ph.D., Professor Yu Yamaguchi, M.D., Ph.D., and their colleagues found that when the ephrin subtype EphrinB activated its EphB receptor, a cascading chemical pathway was triggered that ultimately stimulated an enzyme called synaptojanin-1. This enzyme is essential for a process known as cellular endocytosis, whereby certain chemicals, viruses or other agents are surrounded with a snippet of the cell’s membrane. Endocytosis important as it is the process by which cells take up materials such as neurotransmitters, fat molecules, and foreign bodies like viruses and toxins, from the external environment thus enabling the cell to store, transport or eliminate these materials.

Synaptojanin-1 enables endocytosis when it disassembles a molecular coating on storage vesicles, which allows the cell to continue making new vesicles as needed. "This was a new pathway for ephrin," said Yamaguchi. "Ephrin has been intensively studied for many years, with most attention being paid to its maintenance of the cell’s skeletal structure during development."

Once the biochemical pathway was determined, the researchers then looked at whether ephrin truly increased endocytosis in cells that were not altered genetically. Using rat brain cells, they found that increased signaling did indeed create more vesicles in normal cells. Most important, these new vesicles were important parts of nerve cell synapses, the sophisticated communication relay used in the nervous system.

"We looked at the glutamate receptors at the cell synapse, and depending on other activity, ephrin appeared to decrease the number of glutamate receptors," said Yamaguchi. The regulation of glutamate receptors is crucial to maintaining memory and learning. The strength of a signal through a nerve cell synapse can be enhanced (by increasing the number of receptors) or diminished (by a receptor decrease). "The balance has to be optimal, since too much memory activation can also be a problem," said Yamaguchi.

Yamaguchi’s team, which worked on this project for more than two years, had suspected that ephrins played some important part in nerve cell synapse function. Previous studies had shown that animals injected with addictive drugs had activated EphB receptors, and that there is a connection between synaptojanin-1 and bipolar disorders and schizophrenia. Until now, nobody had made the connection between EphB and the endocytosis involved in neurotransmitter regulation.

"There’s also an increased interest in endocytosis in cancer, in which the process may help diminish anti-proliferation signals and, as a result, trigger tumor progression," said Yamaguchi. "But this is a novel finding in biology, and we can only just begin to speculate on the broader implications of Ephrin and EphB’s activity."

Yamaguchi is a professor of developmental neurobiology at the Burnham Institute, where his research zeros in on the structure and activity of nerve cell synapses. Irie, the lead author of the paper, is a staff scientist in Yamaguchi’s laboratory. Their colleagues included Misako Okuno in Yamaguchi’s laboratory and Elena Pasquale, who also is a professor of developmental neurobiology at Burnham. Pasquale is an internationally known expert in ephrins and their receptors, and Yamaguchi and Pasquale have been collaborating for more than 5 years to elucidate the function of ephrins and their receptors in nerve cells.

Nancy Beddingfield | EurekAlert!
Further information:
http://www.burnham.org

More articles from Life Sciences:

nachricht Progress in Super-Resolution Microscopy
17.12.2018 | Julius-Maximilians-Universität Würzburg

nachricht Communication between neural networks
17.12.2018 | Albert-Ludwigs-Universität Freiburg im Breisgau

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

When a fish becomes fluid

17.12.2018 | Studies and Analyses

Progress in Super-Resolution Microscopy

17.12.2018 | Life Sciences

How electric heating could save CO2 emissions

17.12.2018 | Power and Electrical Engineering

VideoLinks
Science & Research
Overview of more VideoLinks >>>