Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Scientists glimpse dance of skeletons inside neurons

14.09.2010
Research provides insight into developmental disorders, including Williams syndrome

Scientists at Emory University School of Medicine have uncovered how a structural component inside neurons performs two coordinated dance moves when the connections between neurons are strengthened.

The results are published online in the journal Nature Neuroscience, and will appear in a future print issue.

In experiments with neurons in culture, the researchers can distinguish two separate steps during long-term potentiation, an enhancement of communication between neurons thought to lie behind learning and memory. Both steps involve the remodeling of the internal "skeletons" of dendritic spines, small protrusions on the surface of a neuron that receive electrical signals from neighboring cells.

The results hint at why people with Williams syndrome, a developmental disorder caused by a deletion of several genes, including one that alters dendritic spine remodeling, have such an unusual blend of cognitive strengths and weaknesses.

The senior author of the paper is James Zheng, PhD, professor of cell biology and neurology at Emory University School of Medicine. The paper's co-first authors are graduate student Jiaping Gu, now a postdoctoral researcher at New York University, postdoc Chi Wai Lee and graduate student Yanjie Fan.

"We've been looking at the remodeling of dendritic spines, which is a fundamental process for reshaping circuits in the brain," Zheng says. "The anatomy of dendritic spines is altered in many diseases, such as fragile X syndrome and schizophrenia, as well as neurodegenerative disorders like Alzheimer's."

During the process of long-term potentiation, dendritic spines both enlarge and display a greater density of neurotransmitter receptors, the receiver dishes that allow neurons to detect the waves of chemicals other neurons are sending them.

Zheng's team studied this process by engineering a type of neurotransmitter receptor to be fluorescent when introduced into neurons. This particular engineered receptor is fluorescent only when it's on the surface of a cell.

"This allows us to directly visualize the addition of these receptors to the spine surface from their internal stores," he says.

The researchers tested how the movement of the receptors was tied to remodeling of the internal skeleton of the cell, by using drugs that either loosen or freeze the actin cytoskeleton, which forms the main structural support inside dendritic spines.

They then investigated the family of proteins called ADF (actin depolymerizing factor)/cofilin, which Zheng describes as acting like a pair of scissors, severing the links of the actin cytoskeleton.

"Our results suggest that there are two activities that need to be coordinated to strengthen dendritic spines: the cell has to cut actin filaments in order to allow receptors in storage to be added to the surface, but then it has to put away the scissors and stabilize and enlarge the spines," Zheng says.

Williams syndrome is a rare developmental disorder caused by a chromosomal deletion spanning 28 genes, several of which may contribute to changes in cognitive development. One of the genes thought to be responsible encodes the enzyme LIM kinase 1. LIM kinase deactivates ADF/cofilin, which means neurons in Williams syndrome may have an altered ability to remodel dendritic spines.

Williams syndrome impairs affected individuals' perceptions of space as well as their ability to make social judgments, but tends to leave other functions relatively intact. Individuals with Williams syndrome are noted to have an affinity for language and music.

"Cytoskeletal remodeling is required for some aspects of long-term potentiation but also needs to be reigned in. If we change LIM kinase or ADF/cofilin and shift the balance of the cytoskeletal remodeling, that could affect some cognitive processes and not others," Zheng proposes. He also believes that the actin cytoskeleton and its regulation by ADF/cofilin, can be a likely target affected by many neurological disorders involving impaired brain functions.

Pharmaceutical companies have been testing inhibitors of LIM kinases as potential drugs for treating glaucoma, cancer and other diseases. Zheng's team's results indicate that manipulating LIM kinase with drugs could end up perturbing or impairing cognitive processes, he says.

"However, it also could mean that there is a window of time where you could possibly enhance learning or memory formation, based on the dynamics of dendritic spine remodeling," he says.

The research was supported by the National Institutes of Health.

Gu et al. ADF/cofilin-mediated actin dynamics regulate AMPA receptor trafficking during synaptic plasticity. Nature Neurosci. Advance online pub. (2010)

Quinn Eastman | EurekAlert!
Further information:
http://www.emory.edu

More articles from Life Sciences:

nachricht Bare bones: Making bones transparent
27.04.2017 | California Institute of Technology

nachricht Link Discovered between Immune System, Brain Structure and Memory
26.04.2017 | Universität Basel

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Making lightweight construction suitable for series production

More and more automobile companies are focusing on body parts made of carbon fiber reinforced plastics (CFRP). However, manufacturing and repair costs must be further reduced in order to make CFRP more economical in use. Together with the Volkswagen AG and five other partners in the project HolQueSt 3D, the Laser Zentrum Hannover e.V. (LZH) has developed laser processes for the automatic trimming, drilling and repair of three-dimensional components.

Automated manufacturing processes are the basis for ultimately establishing the series production of CFRP components. In the project HolQueSt 3D, the LZH has...

Im Focus: Wonder material? Novel nanotube structure strengthens thin films for flexible electronics

Reflecting the structure of composites found in nature and the ancient world, researchers at the University of Illinois at Urbana-Champaign have synthesized thin carbon nanotube (CNT) textiles that exhibit both high electrical conductivity and a level of toughness that is about fifty times higher than copper films, currently used in electronics.

"The structural robustness of thin metal films has significant importance for the reliable operation of smart skin and flexible electronics including...

Im Focus: Deep inside Galaxy M87

The nearby, giant radio galaxy M87 hosts a supermassive black hole (BH) and is well-known for its bright jet dominating the spectrum over ten orders of magnitude in frequency. Due to its proximity, jet prominence, and the large black hole mass, M87 is the best laboratory for investigating the formation, acceleration, and collimation of relativistic jets. A research team led by Silke Britzen from the Max Planck Institute for Radio Astronomy in Bonn, Germany, has found strong indication for turbulent processes connecting the accretion disk and the jet of that galaxy providing insights into the longstanding problem of the origin of astrophysical jets.

Supermassive black holes form some of the most enigmatic phenomena in astrophysics. Their enormous energy output is supposed to be generated by the...

Im Focus: A Quantum Low Pass for Photons

Physicists in Garching observe novel quantum effect that limits the number of emitted photons.

The probability to find a certain number of photons inside a laser pulse usually corresponds to a classical distribution of independent events, the so-called...

Im Focus: Microprocessors based on a layer of just three atoms

Microprocessors based on atomically thin materials hold the promise of the evolution of traditional processors as well as new applications in the field of flexible electronics. Now, a TU Wien research team led by Thomas Müller has made a breakthrough in this field as part of an ongoing research project.

Two-dimensional materials, or 2D materials for short, are extremely versatile, although – or often more precisely because – they are made up of just one or a...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Expert meeting “Health Business Connect” will connect international medical technology companies

20.04.2017 | Event News

Wenn der Computer das Gehirn austrickst

18.04.2017 | Event News

7th International Conference on Crystalline Silicon Photovoltaics in Freiburg on April 3-5, 2017

03.04.2017 | Event News

 
Latest News

Bare bones: Making bones transparent

27.04.2017 | Life Sciences

Study offers new theoretical approach to describing non-equilibrium phase transitions

27.04.2017 | Physics and Astronomy

From volcano's slope, NASA instrument looks sky high and to the future

27.04.2017 | Earth Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>