Cleaning brain sugar stores could protect against dementia

Summary: New research reveals that sugar metabolism in brain cells can be a crucial defense against Alzheimer’s and related dementias. Scientists found that neurons in flies and human models of tauopathy accumulate excess glycogen, which interrupts the management of cell stress when it cannot be broken down.

Improving glycogen enzyme phosphorylase (Glyp) helped redirect sugar metabolism in a protective pathway, reducing oxidative damage and extending useful life in model organisms. The study also found that dietary restriction and certain medications can increase Glyp’s activity, imitating this effect.

Key facts:

Glycogen accumulation: Neurons in Alzheimer’s models increase excess glycogen, worsening damage related to Tau. Protective via: Glyp activation redirects sugar in the PPP, reducing oxidative stress in neurons. Therapeutic potential: dietary restriction and pharmaceutical treatments that mimic brain health by improving both in flies and human neurons.

Source: Buck Institute

A new study by Buck Institute for research scientists has revealed an amazing player in the battle against Alzheimer’s disease and other forms of dementia: the metabolism of brain sugar.

Published in the metabolism of nature, research discovers how to break down glycogen, a glucose stored form, in neurons can protect the brain from the accumulation of toxic proteins and degeneration.

Glycogen is generally considered a reserve energy source stored in the liver and muscles. Although there are also small amounts in the brain, particularly in support cells called astrocytes, their role in neurons has been discarded for a long time as insignificant.

“This new study challenges that view, and does so with surprising implications,” says Professor Pankaj Kapahi, PhD, main scientist of the study.

“The stored glycogen not only sits there in the brain; it is involved in the pathology.”

The research team, led by Postdoc Sudipta Bar, PHD, discovered that in fly and human tauopathy models (a group of neurodegenerative diseases, including Alzheimer’s), neurons accumulate excessive glycogen.

More importantly, this accumulation seems to contribute to the progression of the disease. Bar says that Tau, the infamous protein that is grouped into tangles in patients with Alzheimer’s, seems to physically unite glycogen, catching it and avoiding its decomposition.

When glycogen cannot be broken down, neurons lose an essential mechanism to control oxidative stress, a key feature in aging and neurodegeneration. When restoring the activity of an enzyme called phosphorylase glycogen (Glyp), which begins the glycogen decomposition process, the researchers found that they could reduce the damage related to the tau in the fruits of the fruits and the neurons derived from human stem cells.

Instead of using glycogen as a fuel for energy production, these neurons supported by enzymes redired the sugar molecules on the Pentosa phosphate pathway (PPP), a critical route to generate NADPH (nicotinamide adenine Dinucleotide phosphate) and glutathione, molecules of molecules that protect against oxidative stress.

“By increasing Glyp’s activity, brain cells could better detoxify the harmful reactive oxygen species, thus reducing damage and even extending the useful life of flies of tauopathy model,” Bar said.

Even more promising, the team showed that the dietary restriction (DR), a well -known intervention to extend the useful life, naturally improved Glyp activity and improved the results related to Tau in flies.

In addition, these pharmacologically imitated using a molecule called 8-Br-Camp, which shows that the benefits of DR could be reproduced by drug-based activation of this sugar cleaning system.

“This work could explain why GLP-1 drugs, now widely used for weight loss, are promises against dementia, potentially imitating dietary restriction,” Kapahi said.

The researchers also confirmed the accumulation of similar glycogen and the protective effects of Glyp on human neurons derived from patients with frontotemporal dementia (FTD), which strengthens the potential of translational therapies.

Kapahi says that the study emphasizes the power of the fly as a model system to discover how metabolic deregulation affects neurodegeneration.

“The work in this simple animal allowed us to move to human neurons in a much more specific way,” he said.

Kapahi also recognizes Buck’s highly collaborative atmosphere as an important factor at work. His laboratory, with experience in the aging of the fly and neurodegeneration, took advantage of the experience in the proteomics in the Schilling laboratory and the Seyfried laboratory (at the University of Emory), as well as the Ellerby laboratory that has experience in IPSC human and neurodegeneration.

Kapahi says that this study not only highlights glycogen metabolism as an unexpected hero in the brain, but also opens a new direction in the search for treatments against Alzheimer’s and related diseases.

“Upon discovering how neurons handle sugar, we can have discovered a new therapeutic strategy: one that goes to the internal chemistry of the cell to combat the decline related to age,” he says.

“As we continue to get older as a society, findings like these offer hope that better understanding, and perhaps rebalance, the hidden sugar code of our brain could unlock powerful tools to combat dementia.”

Co -authors: Buck additional collaborators include Kenneth A. Wilson, Tyler Au Hilsabck, Sydney Alderfer, Jordan B Burton, Samah Shah, Anja Holtz, Enrique M. Carrera, Jennifer N. Beck, Jackson H Chen, Grant Kauwe, Tara E. Tracy, Birgit Schilling and Lisa M. Clarby. Other collaborators include Eric B. Dammer, Fatemeh Seifar and Nicholas T. Seyfried, Emory Center for Neurodegenerative Diseases, Faculty of Medicine of the University of Emory, Atlanta, GA and Ananth Shantaraman, Department of Biochemistry, Faculty of Medicine of the University of Emory, Atlanta, GA, GA, GA, GA, GA, GA.

Financing: The work was supported by NIH Subsidies R01AG038688, R21AG054121, AG045835, R01AG071995, R01AG070193, T32AG000266-23, R01AG061879, P01AG066591 and 1S10 OD016281. Another support came from the Hevolution Foundation, the American Federation of Aging Research, the Larry L. Hillblom Foundation and the Alex and Bob Griswold Catalystx Prize

On this news of metabolism and dementia research

Author: Kris Rebillot
Source: Buck Institute
Contact: Kris Rebillot – Buck Institute
Image: The image is accredited to Neuroscience News

Original research: closed access.
“The decomposition of neuronal glycogen mitigates tauopathy through the reduction of oxidative stress mediated by the Pentosa phosphate route” by Sudipta Bar et al. Nature metabolism

Abstract

The decomposition of neuronal glycogen mitigates tauopathy through the reduction of oxidative stress mediated by the Pentose phosphate pathway

Tauopatías cover a range of neurodegenerative disorders, such as Alzheimer’s disease (AD) and lobular frontotemporal degeneration with inclusions of Tau (FTLD-TAU), for which there are currently no successful treatments.

Here, we show a deteriorated glycogen metabolism in the brain of a Drosophila Melanogaster and people with EA tauopathy model, which indicates a link between the tauopathies and the metabolism of the glycogen.

We demonstrate that the decomposition of neuronal glycogen improves the phenotypes of tauopathy in flies and neurons derived from pluripotent stem cells (IPSC) of people with FTLD-TAU. Glycogen decomposition redirects glucose flow to the Pentosa phosphate pathway and relieves oxidative stress.

Our findings discover a fundamental role for the neuroprotective effects of the dietary restriction (DR) by increasing the decomposition of glycogen.

Mechanically, we show a potential interaction between the Tau protein and glycogen, which suggests a vicious circle in which the union of Tau promotes the accumulation of glycogen in neurons, which in turn exacerbates the accumulation of Tau that further interrupts cell homeostasis.

Our studies identify deteriorated glycogen metabolism as a key seal for tauopathies and offer a promising therapeutic objective in tauopathy and other neurodegenerative diseases.