News

Astrocyte cells in the fruit fly brain are an on-off switch

Sarah DeGenova Ackerman
By Sarah DeGenova Ackerman
May 9, 2021

Neuroplasticity — the ability of neurons to change their structure and function in response to experiences — can be turned off and on by the cells that surround neurons in the brain, according to a new study on fruit flies that I co-authored.

Astrocyte-cells-445x219.jpg
Sarah DeGenova Ackerman, CC BY-ND
The colors in this microscope photo of a fruit fly brain show different types of neurons
and the cells that surround them in the brain.

As fruit fly larvae age, their neurons shift from a highly adaptable state to a stable state and lose their ability to change. During this process, support cells in the brain – called astrocytes — envelop the parts of the neurons that send and receive electrical information. When my team removed the astrocytes, the neurons in the fruit fly larvae remained plastic longer, hinting that somehow astrocytes suppress a neuron's ability to change. We then discovered two specific proteins that regulate neuroplasticity.

Why it matters

The human brain is made up of billions of neurons that form complex connections with one another. Flexibility at these connections is a major driver of learning and memory, but things can go wrong if it isn't tightly regulated. For example, in people, too much plasticity at the wrong time is linked to brain disorders such as epilepsy and Alzheimer's disease. Additionally, reduced levels of the two neuroplasticity-controlling proteins we identified are linked to increased susceptibility to autism and schizophrenia.

Similarly, in our fruit flies, removing the cellular brakes on plasticity permanently impaired their crawling behavior. While fruit flies are of course different from humans, their brains work in very similar ways to the human brain and can offer valuable insight.

Fruit-flies-754x488.jpg
Sarah DeGenova Ackerman, CC BY-ND
As fruit flies develop, special cells surround their neurons and seem to halt neuroplasticity.

One obvious benefit of discovering the effect of these proteins is the potential to treat some neurological diseases. But since a neuron's flexibility is closely tied to learning and memory, in theory, researchers might be able to boost plasticity in a controlled way to enhance cognition in adults. This could, for example, allow people to more easily learn a new language or musical instrument.

How we did the work

My colleagues and I focused our experiments on a specific type of neurons called motor neurons. These control movements like crawling and flying in fruit flies. To figure out how astrocytes controlled neuroplasticity, we used genetic tools to turn off specific proteins in the astrocytes one by one and then measured the effect on motor neuron structure. We found that astrocytes and motor neurons communicate with one another using a specific pair of proteins called neuroligins and neurexins. These proteins essentially function as an off button for motor neuron plasticity.

What still isn't known

My team discovered that two proteins can control neuroplasticity, but we don't know how these cues from astrocytes cause neurons to lose their ability to change.

Additionally, researchers still know very little about why neuroplasticity is so strong in younger animals and relatively weak in adulthood. In our study, we showed that prolonging plasticity beyond development can sometimes be harmful to behavior, but we don't yet know why that is, either.

Fruit-flies-brain-445x254.jpg
Sarah DeGenova Ackerman CC BY-ND
This is a caption.In this image showing a developing fruit fly brain on the right
and the attached nerve cord on the left, the astrocytes are labeled in different
colors showing their wide distribution among neurons.

What's next

I want to explore why longer periods of neuroplasticity can be harmful. Fruit flies are great study organisms for this research because it is very easy to modify the neural connections in their brains. In my team's next project, we hope to determine how changes in neuroplasticity during development can lead to long–term changes in behavior.

There is so much more work to be done, but our research is a first step toward treatments that use astrocytes to influence how neurons change in the mature brain. If researchers can understand the basic mechanisms that control neuroplasticity, they will be one step closer to developing therapies to treat a variety of neurological disorders.

This article is republished from The Conversation under a Creative Commons license. Read the original article.

The Conversation

Sarah DeGenova Ackerman
Sarah DeGenova Ackerman

Sarah DeGenova Ackerman is a postdoctoral fellow at the University of Oregon Institute of Neuroscience and Howard Hughes Medical Institute.

Join the ASBMB Today mailing list

Sign up to get updates on articles, interviews and events.

Latest in Science

Science highlights or most popular articles

A balancing game with implications for neurodegenerative disease
Journal News

A balancing game with implications for neurodegenerative disease

June 8, 2021

The relationship between two proteins, one essential to mitochondrial fission and the other found in Alzheimer’s tissue, might hold the key to how disease alters the fission–fusion balance.

Can people vaccinated against COVID-19 still spread the coronavirus?
News

Can people vaccinated against COVID-19 still spread the coronavirus?

June 6, 2021

Preliminary evidence seems to suggest that someone who’s vaccinated is less likely transmit the virus, but the proof is not yet ironclad.

Addgene expands its collection into antibodies
News

Addgene expands its collection into antibodies

June 4, 2021

The reagent repository Addgene, known for distribution and quality control of plasmids for open science, is expanding into recombinant antibodies and nanobodies in partnership with NeuroMab.

Study reveals experimental targets for lymphoma research
Journal News

Study reveals experimental targets for lymphoma research

June 3, 2021

An enzyme previously linked to lymphoma development may have more functions than previously thought.

Exploring underappreciated molecules and new cities
Interview

Exploring underappreciated molecules and new cities

June 2, 2021

Neurochemist Xianlin Han has been an associate editor for the Journal of Lipid Research since 2019.

Researchers target cell membrane for cancer research
Journal News

Researchers target cell membrane for cancer research

June 1, 2021

“The central idea is that if you alter the composition of the cell membrane, you can potentially alter the functionality of the proteins within the membrane and thus the disease overall.”