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

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Can we see monkeys from space? Emerging technologies to map biodiversity

An international team of scientists has proposed a new multi-disciplinary approach in which an array of new technologies will allow us to map biodiversity and the risks that wildlife is facing at the scale of whole landscapes. The findings are published in Nature Ecology and Evolution. This international research is led by the Kunming Institute of Zoology from China, University of East Anglia, University of Leicester and the Leibniz Institute for Zoo and Wildlife Research.

Using a combination of satellite and ground data, the team proposes that it is now possible to map biodiversity with an accuracy that has not been previously...

Im Focus: Climate satellite: Tracking methane with robust laser technology

Heatwaves in the Arctic, longer periods of vegetation in Europe, severe floods in West Africa – starting in 2021, scientists want to explore the emissions of the greenhouse gas methane with the German-French satellite MERLIN. This is made possible by a new robust laser system of the Fraunhofer Institute for Laser Technology ILT in Aachen, which achieves unprecedented measurement accuracy.

Methane is primarily the result of the decomposition of organic matter. The gas has a 25 times greater warming potential than carbon dioxide, but is not as...

Im Focus: How protons move through a fuel cell

Hydrogen is regarded as the energy source of the future: It is produced with solar power and can be used to generate heat and electricity in fuel cells. Empa researchers have now succeeded in decoding the movement of hydrogen ions in crystals – a key step towards more efficient energy conversion in the hydrogen industry of tomorrow.

As charge carriers, electrons and ions play the leading role in electrochemical energy storage devices and converters such as batteries and fuel cells. Proton...

Im Focus: A unique data centre for cosmological simulations

Scientists from the Excellence Cluster Universe at the Ludwig-Maximilians-Universität Munich have establised "Cosmowebportal", a unique data centre for cosmological simulations located at the Leibniz Supercomputing Centre (LRZ) of the Bavarian Academy of Sciences. The complete results of a series of large hydrodynamical cosmological simulations are available, with data volumes typically exceeding several hundred terabytes. Scientists worldwide can interactively explore these complex simulations via a web interface and directly access the results.

With current telescopes, scientists can observe our Universe’s galaxies and galaxy clusters and their distribution along an invisible cosmic web. From the...

Im Focus: Scientists develop molecular thermometer for contactless measurement using infrared light

Temperature measurements possible even on the smallest scale / Molecular ruby for use in material sciences, biology, and medicine

Chemists at Johannes Gutenberg University Mainz (JGU) in cooperation with researchers of the German Federal Institute for Materials Research and Testing (BAM)...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Plants are networkers

19.06.2017 | Event News

Digital Survival Training for Executives

13.06.2017 | Event News

Global Learning Council Summit 2017

13.06.2017 | Event News

 
Latest News

Supersensitive through quantum entanglement

28.06.2017 | Physics and Astronomy

X-ray photoelectron spectroscopy under real ambient pressure conditions

28.06.2017 | Physics and Astronomy

Mice provide insight into genetics of autism spectrum disorders

28.06.2017 | Health and Medicine

VideoLinks
B2B-VideoLinks
More VideoLinks >>>