Nav: Home

New insights into pruning

June 26, 2018

During the development of the human nervous system, billions of nerve cells connect up in order to communicate with each another. To this end, they use their characteristic long processes, the axons and dendrites. Wrongly matched processes, or those which are no longer needed, degenerate again in the course of development. This degeneration is highly specific, as it affects only the part of a process that is no longer needed. But how do nerve cells determine which part of the axons or dendrites is to degenerate and which is to be preserved? Researchers at the Cells-in-Motion Cluster of Excellence at the University of Münster (Germany) have now for the first time found a correlation between the spatial organization of a nerve cell and the degeneration of its processes. Using fruit flies as a model system, they discovered that the specific arrangement of components of the cytoskeleton influences the direction in which the dendrites of a certain type of nerve cells degenerate during development. "This is the indication of how the degenerative process in neuronal processes is regulated spatially," says Dr. Sebastian Rumpf, a junior researcher group leader at the Cluster of Excellence and head of the study. In the long-term, the results will help scientists to gain a better understanding of how the nervous system develops and how neural pathways connect with each other correctly in the brain. The study has been published in the journal Development.

The detailed story:

"Pruning" is the special term that scientists use to describe the degeneration of nerve cell processes. The mechanisms underlying pruning are the major focus of a team of biologists headed by Sebastian Rumpf who are studying this process in the fruit fly Drosophila melanogaster. The team had discovered earlier that components in the cytoskeleton - the tubular microtubules - perform a key role in the pruning process. "They fall apart, and as a result of this, the dendrites then also degenerate. This process is initiated by a signalling protein that we discovered last year," explains Dr. Svende Herzmann, the lead author of both the earlier and the current studies. "What we then wanted to know," she says, "was: what spatial aspects play a role within the cell during this process?"

Looking at the spatial organization of a nerve cell

To address this question, the researchers marked the microtubules in the dendrites of fruit fly larvae with fluorescent dyes and visualized them by confocal microscopy. They then tracked the behaviour of the microtubules over time. "What we observed was that the microtubules are particularly sensitive at the branching points of the dendrites close to the cell body of the nerve cells and that they disintegrate there first," says Sebastian Rumpf. These gaps spread out into the lateral branches - correlating with the direction of the breakdown of the dendrites themselves.

"We asked ourselves whether the spatial orientation of the microtubules might be important for this," says Svende Herzmann. Microtubules have an inherent polarity: each "tube" has a so-called plus end and a minus end. It was known from earlier studies that the plus ends in the dendrites are always oriented towards the cell body. In axons, it is exactly the other way round - and in these processes, degeneration proceeds from the tips to the branchpoints, the exact opposite orientation of the dendrites.

The researchers then used genetics to inactivate kinesin, an important motor protein, thus changing the uniform alignment of the microtubules in the dendrites. Remarkably, this specific manipulation prevented dendrite degeneration. "Thus, there is a correlation between the spatial organization of the cell and the pruning process," says Sebastian Rumpf. "This is an extremely exciting hypothesis which we will consolidate in further studies." As a next step, the researchers want to use high-resolution microscopy to take a more detailed look at the special processes at the dendrite branching points - which will enable them to find out more about the mechanisms which regulate the degeneration of the nerve cell processes.
-end-
Original publication:

Herzmann S, Gotzelmann I, Reekers L-F, Rumpf S. Spatial regulation of microtubule disruption during dendrite pruning in Drosophila. Development 2018;145. DOI: 10.1242/dev.156950

University of Münster

Related Nerve Cells Articles:

Nerve cells let others "listen in"
How many ''listeners'' a nerve cell has in the brain is strictly regulated.
Nerve cells with energy saving program
Thanks to a metabolic adjustment, the cells can remain functional despite damage to the mitochondria.
Why developing nerve cells can take a wrong turn
Loss of ubiquitin-conjugating enzyme leads to impediment in growth of nerve cells / Link found between cellular machineries of protein degradation and regulation of the epigenetic landscape in human embryonic stem cells
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.
More Nerve Cells News and Nerve Cells Current Events

Trending Science News

Current Coronavirus (COVID-19) News

Top Science Podcasts

We have hand picked the top science podcasts of 2020.
Now Playing: TED Radio Hour

Listen Again: The Power Of Spaces
How do spaces shape the human experience? In what ways do our rooms, homes, and buildings give us meaning and purpose? This hour, TED speakers explore the power of the spaces we make and inhabit. Guests include architect Michael Murphy, musician David Byrne, artist Es Devlin, and architect Siamak Hariri.
Now Playing: Science for the People

#576 Science Communication in Creative Places
When you think of science communication, you might think of TED talks or museum talks or video talks, or... people giving lectures. It's a lot of people talking. But there's more to sci comm than that. This week host Bethany Brookshire talks to three people who have looked at science communication in places you might not expect it. We'll speak with Mauna Dasari, a graduate student at Notre Dame, about making mammals into a March Madness match. We'll talk with Sarah Garner, director of the Pathologists Assistant Program at Tulane University School of Medicine, who takes pathology instruction out of...
Now Playing: Radiolab

What If?
There's plenty of speculation about what Donald Trump might do in the wake of the election. Would he dispute the results if he loses? Would he simply refuse to leave office, or even try to use the military to maintain control? Last summer, Rosa Brooks got together a team of experts and political operatives from both sides of the aisle to ask a slightly different question. Rather than arguing about whether he'd do those things, they dug into what exactly would happen if he did. Part war game part choose your own adventure, Rosa's Transition Integrity Project doesn't give us any predictions, and it isn't a referendum on Trump. Instead, it's a deeply illuminating stress test on our laws, our institutions, and on the commitment to democracy written into the constitution. This episode was reported by Bethel Habte, with help from Tracie Hunte, and produced by Bethel Habte. Jeremy Bloom provided original music. Support Radiolab by becoming a member today at Radiolab.org/donate.     You can read The Transition Integrity Project's report here.