Nav: Home

Neurobiology -- sushi for synapses

July 25, 2019

Synapses between nerve cells in the brain undergo constant remodeling, which is the basis of learning. An Ludwig-Maximilians-Universitaet (LMU) in Munich team has now traced the molecules that direct remodeling and shown that they circulate in the living cell like running sushi.

The human brain is like a long-term construction site - there's always something else to be done. This is certainly true of synapses, the functional links between nerve cells, which are constantly being strengthened, attenuated or demolished. Indeed, this process termed synaptic plasticity is the basis of our ability to store and recall information - in other words, to learn. The instructions for the synthesis of necessary components, which are encoded in molecules known as messenger RNAs (mRNAs), are delivered to the specific synapses that need them by a specialized transport system. But how the blueprints reach their destinations is poorly understood. In order to learn more about the underlying mechanisms, cell biologist Professor Michael Kiebler and his group at the LMU Biomedical Center have now followed the transport of individual mRNAs to specific synapses. Their analysis shows that the same mRNA can be presented to potential addresses several times - a system which the researchers compare to running sushi, the use of an 'endless' conveyor belt to enable patrons to pick and choose from the delicacies on offer.

In order to serve the extensive network of synapses on a typically elongated process termed dendrite, the mRNAs must be transported from the nucleus in the cell body to the terminal branches at the end of the process. To monitor this process, the LMU team used cell cultures derived from neurons isolated from the hippocampus of the rat, which serves as a model for the human hippocampus. "We labelled specific mRNAs in living cells with a fluorescent dye, which enabled us to track their progress in real time," Kiebler explains. "This approach permitted us to determine, for the first time, whether or not a given molecule is delivered directly to a particular synapse, and whether different mRNAs are handled differently in this respect. In one case, we were able to follow how an mRNA entered one of the spine-like processes extended by a dendrite," he says. "Dendrites act as antennas that receive inputs from synapses on other cells." The observations revealed that one and the same mRNA may repeatedly circulate back and forth between the cell body and the nerve processes - like sushi wending its way between the tables in a restaurant - until it finds a synapse that needs it.

Certain recognition sequences located in the segment of the mRNA that follows the stop codon (which marks the end of the protein-coding blueprint) serve as both the postage stamp and the address to direct the molecule to ensure that the molecule reaches the right region of the cell. "We have also demonstrated that, if the postage stamp is left intact, transport from the cell body to the neural processes is more effective and the mRNA is brought closer to the synapse than when it has been removed," says Kiebler. In addition, RNA-binding proteins such as Staufen2 play an important role in the regulation of mRNA transport by this cellular sorting system. Earlier studies had previously shown that Staufen2 is capable of binding several different mRNAs - so that the same mechanism can distribute distinct mRNAs. In addition, the new report confirms early results which had suggested that uptake of the mRNA by the synapse depends on both the nature of the binding protein and the level of activity of the synapse. Taken together, the new data provide further details on the mechanisms underlying the delivery of proteins to synapses, and will have an impact on future efforts to understand the molecular basis of synaptic plasticity in mammals.

Ludwig-Maximilians-Universität München

Related Nerve Cells Articles:

Unique fingerprint: What makes nerve cells unmistakable?
Protein variations that result from the process of alternative splicing control the identity and function of nerve cells in the brain.
Ragweed compounds could protect nerve cells from Alzheimer's
As spring arrives in the northern hemisphere, many people are cursing ragweed, a primary culprit in seasonal allergies.
Fooling nerve cells into acting normal
In a new study, scientists at the University of Missouri have discovered that a neuron's own electrical signal, or voltage, can indicate whether the neuron is functioning normally.
How nerve cells control misfolded proteins
Researchers have identified a protein complex that marks misfolded proteins, stops them from interacting with other proteins in the cell and directs them towards disposal.
The development of brain stem cells into new nerve cells and why this can lead to cancer
Stem cells are true Jacks-of-all-trades of our bodies, as they can turn into the many different cell types of all organs.
Research confirms nerve cells made from skin cells are a valid lab model for studying disease
Researchers from the Salk Institute, along with collaborators at Stanford University and Baylor College of Medicine, have shown that cells from mice that have been induced to grow into nerve cells using a previously published method have molecular signatures matching neurons that developed naturally in the brain.
Bees can count with just four nerve cells in their brains
Bees can solve seemingly clever counting tasks with very small numbers of nerve cells in their brains, according to researchers at Queen Mary University of London.
Nerve cells in the human brain can 'count'
How do we know if we're looking at three apples or four?
How rabies virus moves through nerve cells, and how it might be stopped
Researchers found that the rabies virus travels through neurons differently than other neuron-invading viruses, and that its journey can be stopped by a drug commonly used to treat amoebic dysentery.
Direct conversion of non-neuronal cells into nerve cells
Researchers of the Mainz University Medical Center discovered that on the way to becoming neurons pericytes need to go through a neural stem cell-like state.
More Nerve Cells News and Nerve Cells Current Events

Top Science Podcasts

We have hand picked the top science podcasts of 2019.
Now Playing: TED Radio Hour

In & Out Of Love
We think of love as a mysterious, unknowable force. Something that happens to us. But what if we could control it? This hour, TED speakers on whether we can decide to fall in — and out of — love. Guests include writer Mandy Len Catron, biological anthropologist Helen Fisher, musician Dessa, One Love CEO Katie Hood, and psychologist Guy Winch.
Now Playing: Science for the People

#541 Wayfinding
These days when we want to know where we are or how to get where we want to go, most of us will pull out a smart phone with a built-in GPS and map app. Some of us old timers might still use an old school paper map from time to time. But we didn't always used to lean so heavily on maps and technology, and in some remote places of the world some people still navigate and wayfind their way without the aid of these tools... and in some cases do better without them. This week, host Rachelle Saunders...
Now Playing: Radiolab

Dolly Parton's America: Neon Moss
Today on Radiolab, we're bringing you the fourth episode of Jad's special series, Dolly Parton's America. In this episode, Jad goes back up the mountain to visit Dolly's actual Tennessee mountain home, where she tells stories about her first trips out of the holler. Back on the mountaintop, standing under the rain by the Little Pigeon River, the trip triggers memories of Jad's first visit to his father's childhood home, and opens the gateway to dizzying stories of music and migration. Support Radiolab today at