Nav: Home

TSRI researchers uncover culprit in Parkinson's brain cell die-off

March 05, 2018

JUPITER, FL -- March 5, 2018 -- An estimated 10 million people worldwide are living with Parkinson's disease--an incurable neurodegenerative disorder that leads to an increasing loss of motor control.

If we could peer into the brains of these patients, we'd see two hallmarks of the disease. First, we'd see a die-off of the brain cells that produce a chemical called dopamine. We'd also see protein clumps called Lewy bodies inside the neurons.

Corinne Lasmézas, DVM, PhD, a professor on the Florida campus of The Scripps Research Institute (TSRI), believes a key to treating Parkinson's is to study possible links between these two phenomena.

Now her group has discovered a connection between neuronal death and Lewy bodies. The research, published recently in the journal Proceedings of the National Academy of Sciences, offers an explanation for why neurons die off in the first place.

'This study identifies the missing link between Lewy bodies and the type of damage that's been observed in neurons affected by Parkinson's," says Lasmézas, senior author of the study. "Parkinson's is a disorder of the mitochondria, and we discovered how Lewy bodies are releasing a partial break-down product that has a high tropism for the mitochondria and destroys their ability to produce energy."

Toxic protein travels to mitochondria to do damage

Lewy bodies were described a century ago, but it was not until 1997 that scientists discovered they were made of clumps of a misfolded protein called α-synuclein. When it's not misfolded, α-synuclein is believed to carry out functions related to the transmission of signals between neurons.

Lasmézas' research focuses on neurological disorders caused by misfolded proteins, such as Alzheimer's, Parkinson's, prion diseases, frontotemporal dementia and amyotrophic lateral sclerosis (ALS, Lou Gehrig's disease). She uses lab models, including cell cultures and mice, to study these diseases.

In the current study, Lasmézas and her team looked at cell cultures of neurons that were induced to accumulate fibrils made of misfolded α-synuclein, mimicking Lewy bodies in patients with Parkinson's. They discovered that when α-synuclein fibrils are broken down, it often creates a smaller protein clump, which they named pα-syn* (pronounced "P-alpha-syn-star").

"Sometimes the nerve cells can efficiently degrade the α-synuclein fibrils, but if they get overwhelmed, the degradation may be incomplete," she explains. "And it turns out that the result of that partial degradation, pα-syn*, is toxic."

Diego Grassi, PhD, a research associate in Lasmézas' lab, made this discovery by labeling the pα-syn* with an antibody so he could follow it throughout the cell after it was created. He observed that pα-syn* traveled and attached itself to the mitochondria. Further investigation revealed that once the pα-syn* attached, the mitochondria started to break down. These fragmented mitochondria lose their ability to carry an electrochemical signal and produce energy.

The researchers followed up with an analysis of mouse and human brain samples. They confirmed the existence of pα-syn* in the dopamine-producing neurons.

"The Lewy bodies are big aggregates and they're sitting in the cell, but they don't come into direct contact with the mitochondria in the way pα-syn* does," Lasmézas explains. "With Diego's discovery, we've made a direct connection between the protein α-synuclein and the downstream effects that are observed when brain cells become damaged in Parkinson's."

Lasmézas plans to continue studying the connection between misfolded proteins and the destruction of mitochondria in neurons. "What we found may not be the only mechanism of toxicity, but we know it's important," she says. "This paper is about identifying where pα-syn* comes from and what it does to the mitochondria, but there's obviously, mechanistically, a lot that we still don't know."

She says that these findings also have implications for designing treatments for Parkinson's, noting that some drugs currently under development are focused on getting rid of larger fibrils that make up Lewy bodies.

"It's important to be aware that when Lewy bodies are broken down, these toxic substances may be created," Lasmézas says. In addition, she adds, the discovery of pα-syn* as an important component of the disease process points to a new target for creating drugs slowing disease progression.
-end-
First author of the study, "Identification of a highly neurotoxic α-synuclein species inducing mitochondrial damage and mitophagy in Parkinson's disease," was Diego Grassi. Other authors were Shannon Howard, Minghai Zhou, Natalia Diaz-Perez, and Philip LoGrasso of The Scripps Research Institute; Nicolai T. Urban, Debbie Guerrero-Given, and Naomi Kamasawa of the Max Planck Florida Institute for Neuroscience; and Laura Volpicelli-Daley of the University of Alabama at Birmingham.

This research was funded by the National Institute of Neurological Disorders and Stroke (grant R01NS085223), the Michael J. Fox Foundation and the Saul and Theresa Esman Foundation.

About The Scripps Research Institute

The Scripps Research Institute (TSRI) is one of the world's largest independent, not-for-profit organizations focusing on research in the biomedical sciences. TSRI is internationally recognized for its contributions to science and health, including its role in laying the foundation for new treatments for cancer, rheumatoid arthritis, hemophilia, and other diseases. An institution that evolved from the Scripps Metabolic Clinic founded by philanthropist Ellen Browning Scripps in 1924, the institute now employs more than 2,500 people on its campuses in La Jolla, CA, and Jupiter, FL, where its renowned scientists--including two Nobel laureates and 20 members of the National Academies of Science, Engineering or Medicine--work toward their next discoveries. The institute's graduate program, which awards PhD degrees in biology and chemistry, ranks among the top ten of its kind in the nation. In October 2016, TSRI announced a strategic affiliation with the California Institute for Biomedical Research (Calibr), representing a renewed commitment to the discovery and development of new medicines to address unmet medical needs. For more information, see http://www.scripps.edu.

Scripps Research Institute

Related Neurons Articles:

How do we get so many different types of neurons in our brain?
SMU (Southern Methodist University) researchers have discovered another layer of complexity in gene expression, which could help explain how we're able to have so many billions of neurons in our brain.
These neurons affect how much you do, or don't, want to eat
University of Arizona researchers have identified a network of neurons that coordinate with other brain regions to influence eating behaviors.
Mood neurons mature during adolescence
Researchers have discovered a mysterious group of neurons in the amygdala -- a key center for emotional processing in the brain -- that stay in an immature, prenatal developmental state throughout childhood.
Astrocytes protect neurons from toxic buildup
Neurons off-load toxic by-products to astrocytes, which process and recycle them.
Connecting neurons in the brain
Leuven researchers uncover new mechanisms of brain development that determine when, where and how strongly distinct brain cells interconnect.
The salt-craving neurons
Pass the potato chips, please! New research discovers neural circuits that regulate craving and satiation for salty tastes.
When neurons are out of shape, antidepressants may not work
Selective serotonin reuptake inhibitors (SSRIs) are the most commonly prescribed medication for major depressive disorder (MDD), yet scientists still do not understand why the treatment does not work in nearly thirty percent of patients with MDD.
Losing neurons can sometimes not be that bad
Current thinking about Alzheimer's disease is that neuronal cell death in the brain is to blame for the cognitive havoc caused by the disease.
Neurons that fire together, don't always wire together
As the adage goes 'neurons that fire together, wire together,' but a new paper published today in Neuron demonstrates that, in addition to response similarity, projection target also constrains local connectivity.
Scientists accidentally reprogram mature mouse GABA neurons into dopaminergic-like neurons
Attempting to make dopamine-producing neurons out of glial cells in mouse brains, a group of researchers instead converted mature inhibitory neurons into dopaminergic cells.
More Neurons News and Neurons Current Events

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

Rethinking Anger
Anger is universal and complex: it can be quiet, festering, justified, vengeful, and destructive. This hour, TED speakers explore the many sides of anger, why we need it, and who's allowed to feel it. Guests include psychologists Ryan Martin and Russell Kolts, writer Soraya Chemaly, former talk radio host Lisa Fritsch, and business professor Dan Moshavi.
Now Playing: Science for the People

#538 Nobels and Astrophysics
This week we start with this year's physics Nobel Prize awarded to Jim Peebles, Michel Mayor, and Didier Queloz and finish with a discussion of the Nobel Prizes as a way to award and highlight important science. Are they still relevant? When science breakthroughs are built on the backs of hundreds -- and sometimes thousands -- of people's hard work, how do you pick just three to highlight? Join host Rachelle Saunders and astrophysicist, author, and science communicator Ethan Siegel for their chat about astrophysics and Nobel Prizes.