Anti-inflammatory Molecules Decline in the Aging Brain

Calendar November 1, 2022 | Posted by admin

Aging involves complicated plot twists and a large cast of characters: inflammation, stress, metabolism changes, and many others.

Now, a team of Salk Institute and UC San Diego scientists reveal another factor implicated in the aging process—a class of lipids called SGDGs (3-sulfogalactosyl diacylglycerols) that decline in the brain with age and may have anti-inflammatory effects.

 

The research, published in Nature Chemical Biology, helps unravel the molecular basis of brain aging, reveals new mechanisms underlying age-related neurological diseases, and offers future opportunities for therapeutic intervention.

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Toxic Fatty Acids Play a Critical Role in Brain Cell Death

Calendar October 8, 2021 | Posted by admin

Rodent studies led by researchers at NYU Grossman School of Medicine have found that cells called astrocytes, which normally nourish neurons, also release toxic fatty acids after neurons are damaged. The team suggests that this phenomenon is likely the driving factor behind most, if not all, diseases that affect brain function, as well as the natural breakdown of brain cells seen in aging.

“Our findings show that the toxic fatty acids produced by astrocytes play a critical role in brain cell death and provide a promising new target for treating, and perhaps even preventing, many neurodegenerative diseases,” said Shane Liddelow, PhD, who is co-senior and corresponding author of the researchers’ published paper in Nature. In their report, which is titled, “Neurotoxic reactive astrocytes induce cell death via saturated lipids,” the team concluded. “The findings highlight the important role of the astrocyte reactivity response in CNS injury and neurodegenerative disease and the relatively unexplored role of lipids in CNS signaling.”

 

Astrocytes—star-shaped glial cells of the central nervous system (CNS)—undergo functional changes in response to CNS disease and injury, but the mechanisms that underlie these changes and their therapeutic relevance remain unclear, the authors noted. Interestingly, previous research has pointed to astrocytes as the culprits behind cell death seen in Parkinson’s disease and dementia, among other neurodegenerative diseases. “Astrocytes regulate the response of the central nervous system to disease and injury, and have been hypothesized to actively kill neurons in neurodegenerative disease,” the researchers stated. But while many experts believed that these cells release a neuron-killing molecule to clear away damaged brain cells, the identity of the toxin has remained a mystery.

The studies by Liddelow and colleagues now provide what they say is the first evidence that tissue damage prompts astrocytes to produce two kinds of fats, long-chain saturated free fatty acids and phosphatidylcholines. These fats then trigger cell death in damaged neurons. For their investigation, researchers analyzed the molecules released by astrocytes collected from rodents. “Previous evidence suggested that the toxic activity of reactive astrocytes is mediated by a secreted protein, so we first sought to identify the toxic agent by protein mass spectrometry of reactive versus control astrocyte conditioned medium (ACM),” they wrote.

Source: https://www.genengnews.com/

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How Do Killer Immune Cells Protect Themselves?

Calendar December 2, 2019 | Posted by admin

White blood cells, which release a toxic potion of proteins to kill cancerous and virus-infected cells, are protected from any harm by the physical properties of their cell envelopes, find scientists from UCL and the Peter MacCallum Cancer Centre in Melbourne. Until now, it has been a mystery to scientists how these white blood cells – called cytotoxic lymphocytes – avoid being killed by their own actions and the discovery could help explain why some tumours are more resistant than others to recently developed cancer immunotherapies.

The research, published in Nature Communications, highlights the role of the physical properties of the white blood cell envelope, namely the molecular order and electric charge, in providing such protection.

“Cytotoxic lymphocytes, or white blood cells, rid the body of disease by punching holes in rogue cells and by injecting poisonous enzymes inside. Remarkably, they can do this many times in a row, without harming themselves. We now know what effectively prevents these white blood cells from committing suicide every time they kill one of their targets,” according to Professor Bart Hoogenboom (London Centre for Nanotechnology, UCL Physics & Astronomy and UCL Structural & Molecular Biology), co-author of the study.

The scientists made the discovery by studying perforin, which is the protein responsible for the hole-punching. They found that perforin’s attachment to the cell surface strongly depends on the order and packing of the molecules – so-called lipids – in the membrane that surrounds and protects the white blood cells.

Source: https://www.ucl.ac.uk/

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New Theory To Prevent Alzheimer’s

Calendar August 15, 2019 | Posted by admin

Alzheimer’s disease, the most common cause of dementia among the elderly, is characterized by plaques and tangles in the brain, with most efforts at finding a cure focused on these abnormal structures. But a University of California, Riverside, research team has identified alternate chemistry that could account for the various pathologies associated with the disease. Plaques and tangles have so far been the focus of attention in this progressive disease that currently afflicts more than 5.5 million people in the United States. Plaques, deposits of a protein fragment called beta-amyloid, look like clumps in the spaces between neurons. Tangles, twisted fibers of tau, another protein, look like bundles of fibers that build up inside cells.

“The dominant theory based on beta-amyloid buildup has been around for decades, and dozens of clinical trials based on that theory have been attempted, but all have failed,” said Ryan R. Julian, a professor of chemistry who led the research team. “In addition to plaques, lysosomal storage is observed in brains of people who have Alzheimer’s disease. Neurons — fragile cells that do not undergo cell division — are susceptible to lysosomal problems, specifically, lysosomal storage, which we report is a likely cause of Alzheimer’s disease.”

An organelle within the cell, the lysosome serves as the cell’s trashcan. Old proteins and lipids get sent to the lysosome to be broken down to their building blocks, which are then shipped back out to the cell to be built into new proteins and lipids. To maintain functionality, the synthesis of proteins is balanced by the degradation of proteins.

The lysosome, however, has a weakness: If what enters does not get broken down into little pieces, then those pieces also can’t leave the lysosome. The cell decides the lysosome is not working and “stores” it, meaning the cell pushes the lysosome to the side and proceeds to make a new one. If the new lysosome also fails, the process is repeated, resulting in lysosome storage.

“The brains of people who have lysosomal storage disorder, another well-studied disease, and the brains of people who have Alzheimer’s disease are similar in terms of lysosomal storage,” Julian said. “But lysosomal storage disorder symptoms show up within a few weeks after birth and are often fatal within a couple of years. Alzheimer’s disease occurs much later in life. The time frames are, therefore, very different.”

Julian’s collaborative team of researchers in the Department of Chemistry and the Division of Biomedical Sciences at UC Riverside posits that long-lived proteins, including beta-amyloid and tau, can undergo spontaneous modifications that can make them undigestible by the lysosomes. “Long-lived proteins become more problematic as we age and could account for the lysosomal storage seen in Alzheimer’s, an age-related disease,” Julian said. “If we are correct, it would open up new avenues for treatment and prevention of this disease.”

Study results appear in ACS Central Science, a journal of the American Chemical Society.

Source: https://news.ucr.edu/

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