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 Cryo-electron microscopy achieves unprecedented resolution using new computational methods
24.03.2017 | DOE/Lawrence Berkeley National Laboratory

nachricht How cheetahs stay fit and healthy
24.03.2017 | Forschungsverbund Berlin e.V.

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Giant Magnetic Fields in the Universe

Astronomers from Bonn and Tautenburg in Thuringia (Germany) used the 100-m radio telescope at Effelsberg to observe several galaxy clusters. At the edges of these large accumulations of dark matter, stellar systems (galaxies), hot gas, and charged particles, they found magnetic fields that are exceptionally ordered over distances of many million light years. This makes them the most extended magnetic fields in the universe known so far.

The results will be published on March 22 in the journal „Astronomy & Astrophysics“.

Galaxy clusters are the largest gravitationally bound structures in the universe. With a typical extent of about 10 million light years, i.e. 100 times the...

Im Focus: Tracing down linear ubiquitination

Researchers at the Goethe University Frankfurt, together with partners from the University of Tübingen in Germany and Queen Mary University as well as Francis Crick Institute from London (UK) have developed a novel technology to decipher the secret ubiquitin code.

Ubiquitin is a small protein that can be linked to other cellular proteins, thereby controlling and modulating their functions. The attachment occurs in many...

Im Focus: Perovskite edges can be tuned for optoelectronic performance

Layered 2D material improves efficiency for solar cells and LEDs

In the eternal search for next generation high-efficiency solar cells and LEDs, scientists at Los Alamos National Laboratory and their partners are creating...

Im Focus: Polymer-coated silicon nanosheets as alternative to graphene: A perfect team for nanoelectronics

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are less stable. Now researchers at the Technical University of Munich (TUM) have, for the first time ever, produced a composite material combining silicon nanosheets and a polymer that is both UV-resistant and easy to process. This brings the scientists a significant step closer to industrial applications like flexible displays and photosensors.

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are...

Im Focus: Researchers Imitate Molecular Crowding in Cells

Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to simulate these confined natural conditions in artificial vesicles for the first time. As reported in the academic journal Small, the results are offering better insight into the development of nanoreactors and artificial organelles.

Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

International Land Use Symposium ILUS 2017: Call for Abstracts and Registration open

20.03.2017 | Event News

CONNECT 2017: International congress on connective tissue

14.03.2017 | Event News

ICTM Conference: Turbine Construction between Big Data and Additive Manufacturing

07.03.2017 | Event News

 
Latest News

Argon is not the 'dope' for metallic hydrogen

24.03.2017 | Materials Sciences

Astronomers find unexpected, dust-obscured star formation in distant galaxy

24.03.2017 | Physics and Astronomy

Gravitational wave kicks monster black hole out of galactic core

24.03.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>