Featured Research

from universities, journals, and other organizations

Understanding The Neuron's Green Architecture

Date:
September 24, 2007
Source:
Howard Hughes Medical Institute
Summary:
Being green is a lifestyle. Turns out, each of your neurons is deeply committed to that green lifestyle - and you didn't even know it. In just a thousandth of a second, a neuron can dump up to 5,000 molecules of its chemical messenger - a neurotransmitter - into the synapse, where it will trigger an impulse in a neighboring nerve cell. The neuron is a recycler par excellence when it comes to these neurotransmitters. Neurons must not only ready neurotransmitter receptors to receive the signals coming fast and furious, but they must also recycle receptors that have been used. And you thought you had recycling problems?

Being green is a lifestyle. Turns out, each of your neurons is deeply committed to that green lifestyle - and you didn't even know it. In just a thousandth of a second, a neuron can dump up to 5,000 molecules of its chemical messenger - a neurotransmitter - into the synapse, where it will trigger an impulse in a neighboring nerve cell.

The neuron is a recycler par excellence when it comes to these neurotransmitters. Neurons must not only ready neurotransmitter receptors to receive the signals coming fast and furious, but they must also recycle receptors that have been used. And you thought you had recycling problems?

Researchers have now determined the identity of one of the more significant features of a neuron's green architecture. They identified a cellular anchor that keeps the recycling machinery in place in the cell membrane so that it can recycle spent neurotransmitter receptors. The anchor is critical; without it, neurons would not be able to remove used receptors and install new ones in the cell membrane. And beyond being a mere anchor, the protein is part of a larger ensemble of proteins that help neurons adjust and maintain the strength of their signaling connections.

Howard Hughes Medical Institute investigator Michael Ehlers and his colleagues published their discovery in the September 20, 2007, issue of the journal Neuron. Ehlers and his research team at Duke University Medical Center collaborated on the study with scientists from the University of North Carolina at Chapel Hill.

In their experiments, the researchers were looking for a molecule that keeps endocytic zones anchored in the neuronal membrane. These endocytic zones house the machinery for recycling neurotransmitter receptors. Neurons use neurotransmitters to communicate with one another across synapses, the junctions between them. They release neurotransmitters into a synapse to trigger or inhibit a nerve impulse in a neighboring neuron.

Ehlers said neuroscientists have been searching for a better understanding of how the recycling areas (endocytic zones) are connected to a region of the membrane called the postsynaptic density, where receptors cluster to receive neurotransmitter signals.

In previous studies, Ehlers and his colleagues established that endocytic zones are the sites where neurotransmitter receptors are recycled. “We found these hot spots of endocytosis right next to each postsynaptic density, but we wondered what molecular mechanism could couple these two membrane domains,” said Ehlers. “Understanding this coupling mechanism is crucial for beginning to understand how neurons solve the problem of modifying the strength of a single synapse.”

The coupling mechanism is also critical in permitting neurons to adjust the number of receptors on their surface—and then preserving that modification for a long period of time. “The challenge for the neuron,” said Ehlers, “is to precisely regulate the number of receptors, even as they are constantly escaping the postsynaptic density. There had to be a mechanism to capture escaped receptors for recycling.”

In searching for the anchor molecule for endocytic zones, the researchers concentrated on a protein called dynamin-3. They chose dynamin-3 because, although its function was unknown, it is well concentrated in the brain and is a member of a family of proteins that chain together to form molecular nooses that pinch off vesicles in the receptor recycling process.

The researchers employed fluorescent imaging studies that revealed that dynamin-3 concentrates at the endocytic zone and couples itself to another protein, called Homer. Homer was known to attach to the postsynaptic density. Molecular studies revealed dynamin-3 can latch onto Homer by forming chains of dynamin proteins that bridge the distance between the endocytic zone and the postsynaptic density.

Ehlers noted that one of his group's key experiments showed that the endocytic machinery uncoupled from the postsynaptic density when dynamin-3 was knocked out in the neurons. “Even though our molecular analysis showed quite clearly that dynamin-3 functions as a connector, it was really surprising that disrupting dynamin-3 so completely caused this uncoupling,” said Ehlers. “This gives a tool to do experiments nobody has done before—exploring what happens when you no longer have recycling going on right next to the postsynaptic density.”

“There are still a lot of molecular details of the dynamin-3 mechanism we don't understand,” said Ehlers. “But we now have the tools to disrupt it selectively, to further explore its function. Furthermore, we can now manipulate the pools of receptors and ask interesting questions about how availability of receptors affects the ability of the synapse to undergo critical plastic change in its strength,” he said. “This process is fundamental for normal brain development and likely goes awry in disorders of cognition and memory.”


Story Source:

The above story is based on materials provided by Howard Hughes Medical Institute. Note: Materials may be edited for content and length.


Cite This Page:

Howard Hughes Medical Institute. "Understanding The Neuron's Green Architecture." ScienceDaily. ScienceDaily, 24 September 2007. <www.sciencedaily.com/releases/2007/09/070919144501.htm>.
Howard Hughes Medical Institute. (2007, September 24). Understanding The Neuron's Green Architecture. ScienceDaily. Retrieved September 17, 2014 from www.sciencedaily.com/releases/2007/09/070919144501.htm
Howard Hughes Medical Institute. "Understanding The Neuron's Green Architecture." ScienceDaily. www.sciencedaily.com/releases/2007/09/070919144501.htm (accessed September 17, 2014).

Share This



More Mind & Brain News

Wednesday, September 17, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

FDA Eyes Skin Shocks Used at Mass. School

FDA Eyes Skin Shocks Used at Mass. School

AP (Sep. 15, 2014) The FDA is considering whether to ban devices used by the Judge Rotenberg Educational Center in Canton, Massachusetts, the only place in the country known to use electrical skin shocks as aversive conditioning for aggressive patients. (Sept. 15) Video provided by AP
Powered by NewsLook.com
Shocker: Journalists Are Utterly Addicted To Coffee

Shocker: Journalists Are Utterly Addicted To Coffee

Newsy (Sep. 13, 2014) A U.K. survey found that journalists consumed the most amount of coffee, but that's only the tip of the coffee-related statistics iceberg. Video provided by Newsy
Powered by NewsLook.com
'Magic Mushrooms' Could Help Smokers Quit

'Magic Mushrooms' Could Help Smokers Quit

Newsy (Sep. 11, 2014) In a small study, researchers found that the majority of long-time smokers quit after taking psilocybin pills and undergoing therapy sessions. Video provided by Newsy
Powered by NewsLook.com
'Fat Shaming' Might Actually Cause Weight Gain

'Fat Shaming' Might Actually Cause Weight Gain

Newsy (Sep. 11, 2014) A study for University College London suggests obese people who are discriminated against gain more weight than those who are not. Video provided by Newsy
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

    Environment News

      Technology News



      Save/Print:
      Share:

      Free Subscriptions


      Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

      Get Social & Mobile


      Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

      Have Feedback?


      Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
      Mobile: iPhone Android Web
      Follow: Facebook Twitter Google+
      Subscribe: RSS Feeds Email Newsletters
      Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins