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:

How hearing loss can change the way nerve cells are wired
Even short-term blockages in hearing can lead to remarkable changes in the auditory system, altering the behavior and structure of nerve cells that relay information from the ear to the brain, according to a new University at Buffalo study.
Lab-grown nerve cells make heart cells throb
Researchers at Johns Hopkins report that a type of lab-grown human nerve cells can partner with heart muscle cells to stimulate contractions.
Nerve-insulating cells more diverse than previously thought
Oligodendrocytes, a type of brain cell that plays a crucial role in diseases such as multiple sclerosis, are more diverse than have previously been thought, according to a new study by researchers at Karolinska Institutet in Sweden.
Aggregated protein in nerve cells can cause ALS
Persons with the serious disorder ALS, can have a genetic mutation that causes the protein SOD1 to aggregate in motor neurons in the brain and spinal cord.
Aggression causes new nerve cells to be generated in the brain
A group of neurobiologists from Russia and the USA, including Dmitry Smagin, Tatyana Michurina, and Grigori Enikolopov from Moscow Institute of Physics and Technology, have proven experimentally that aggression has an influence on the production of new nerve cells in the brain.
Researchers grow retinal nerve cells in the lab
Johns Hopkins researchers have developed a method to efficiently turn human stem cells into retinal ganglion cells, the type of nerve cells located within the retina that transmit visual signals from the eye to the brain.
Nerve cells warn brain of damage to the inner ear
Some nerve cells in the inner ear can signal tissue damage in a way similar to pain-sensing nerve cells in the body, according to new research from Johns Hopkins.
It takes a lot of nerve: Scientists make cells to aid peripheral nerve repair
Peripheral nerve injuries, such as those resulting from neuropathies, physical trauma or surgery, are common and can cause partial or complete loss of nerve function and a reduced quality of life.
Nerve cells use each other as maps
When nerve cells form in an embryo they have to be guided to their final position by navigating a kind of molecular and cellular 'map' in order to function properly.
What hundreds of biomolecules tell us about our nerve cells
Researchers at the Luxembourg Centre for Systems Biomedicine, of the University of Luxembourg, have, under Dr.

Related Nerve Cells Reading:

Best Science Podcasts 2019

We have hand picked the best science podcasts for 2019. Sit back and enjoy new science podcasts updated daily from your favorite science news services and scientists.
Now Playing: TED Radio Hour

Do animals grieve? Do they have language or consciousness? For a long time, scientists resisted the urge to look for human qualities in animals. This hour, TED speakers explore how that is changing. Guests include biological anthropologist Barbara King, dolphin researcher Denise Herzing, primatologist Frans de Waal, and ecologist Carl Safina.
Now Playing: Science for the People

#SB2 2019 Science Birthday Minisode: Mary Golda Ross
Our second annual Science Birthday is here, and this year we celebrate the wonderful Mary Golda Ross, born 9 August 1908. She died in 2008 at age 99, but left a lasting mark on the science of rocketry and space exploration as an early woman in engineering, and one of the first Native Americans in engineering. Join Rachelle and Bethany for this very special birthday minisode celebrating Mary and her achievements. Thanks to our Patreons who make this show possible! Read more about Mary G. Ross: Interview with Mary Ross on Lash Publications International, by Laurel Sheppard Meet Mary Golda...