(Press-News.org) How do nerve cells -- which can each be up to three feet long in humans -- keep from rupturing or falling apart?
Axons, the long, cable-like projections on neurons, are made stronger by a unique modification of the common molecular building block of the cell skeleton. The finding, which may help guide the search for treatments for neurodegenerative diseases, was reported in the April 10 issue of Neuron by researchers at the University of Illinois at Chicago College of Medicine.
Microtubules are long, hollow cylinders that are a component of the cytoskeleton in all cells of the body. They also support transport of molecules within the cell and facilitate growth. They are made up of polymers of a building-block substance called tubulin.
"Except for neurons, cells' microtubules are in constant dynamic flux -- being taking apart and rebuilt," says Scott Brady, professor and head of anatomy and cell biology at UIC and principal investigator on the study. But only neurons grow so long, he said, and once created they must endure throughout a person's life, as much as 80 to 100 years. The microtubules of neurons are able to withstand laboratory conditions that cause other cells' microtubules to break apart.
Brady had been able to show some time ago that the neuron's stability depended on a modification of tubulin.
"But when we tried to figure out what the modification was, we didn't have the tools," he said.
Yuyu Song, a former graduate student in Brady's lab and the first author of the study, took up the question. "It was like a detective story with many possibilities that had to be ruled out one by one," she said. Song, who is now a post-doctoral fellow at Howard Hughes Medical Institute at Yale School of Medicine, used a variety of methods to determine the nature of the modification and where it occurs.
She found that tubulin is modified by the chemical bonding of polyamines, positively charged molecules, at sites that might otherwise be chinks where tubulin could be broken down, causing the microtubules to fall apart. She was also able to show that the enzyme transglutaminase was responsible for adding the protective polyamines.
The blocking of a vulnerable site on tubulin would explain the extraordinary stability of neuron microtubules, said Brady. However, convincing others required the "thorough and elegant work" that Song brought to it, he said. "It's such a radical finding that we needed to show all the key steps along the way."
The authors also note that increased microtubule stability correlates with decreased neuronal plasticity -- and both occur in the process of aging and in some neurodegenerative diseases. Continued research, they say, may help identify novel therapeutic approaches to prevent neurodegeneration or allow regeneration.
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Laura Kirkpatrick of Lexicon Pharmaceuticals, Alexander Schilling and Donald Helseth of UIC, Jeffery W. Keillor of the University of Ottawa, and Gail Johnson of the University of Rochester Medical Center also contributed to the study.
The study was supported by grants (NS23868 and NS23320) from the National Institute of Neurological Disorders and Stroke.
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COLUMBIA, Mo. – People with an Autism Spectrum Disorder (ASD) often have trouble communicating and interacting with others because they process language, facial expressions and social cues differently. Previously, researchers found that propranolol, a drug commonly used to treat high blood pressure, anxiety and panic, could improve the language abilities and social functioning of people with an ASD. Now, University of Missouri investigators say the prescription drug also could help improve the working memory abilities of individuals with autism.
Working memory represents ...
April 15, 2013 – San Francisco - A brain-training task that increases the number of items an individual can remember over a short period of time may boost performance in other problem-solving tasks by enhancing communication between different brain areas. The new study being presented this week in San Francisco is one of a growing number of experiments on how working-memory training can measurably improve a range of skills – from multiplying in your head to reading a complex paragraph.
"Working memory is believed to be a core cognitive function on which many types of ...
AURORA, Colo. (April 15, 2013) – A newly published study of patients with pulmonary fibrosis has discovered multiple genetic variations that should help with future efforts to treat the disease.
Pulmonary fibrosis is a condition where lung tissue becomes thickened, stiff and scarred. Currently in the United States, there are no drugs approved for use in cases of the condition's most common and severe form, which is known as idiopathic pulmonary fibrosis (IPF) because the cause of the disease is not known. In those cases, the median survival time after diagnosis is two ...
As small and active flying mammals, bats have very high mass-specific energy requirements and as such continually adjust their rates of activity and metabolism in response to ambient temperature and other seasonal variation. In particular, during the autumn mating season, male bats must carefully balance time spent foraging (to gain enough fat to last the winter hibernation) with time spent finding a mate. Because both activities require significant effort, how do male bats do it? In an upcoming issue of Physiological and Biochemical Zoology, Nina Becker and colleagues ...
Specific DNA once dismissed as junk plays an important role in brain development and might be involved in several devastating neurological diseases, UC San Francisco scientists have found.
Their discovery in mice is likely to further fuel a recent scramble by researchers to identify roles for long-neglected bits of DNA within the genomes of mice and humans alike.
While researchers have been busy exploring the roles of proteins encoded by the genes identified in various genome projects, most DNA is not in genes. This so-called junk DNA has largely been pushed aside ...
AUDIO:
Learn about research on decision-making in this podcast with Carlos Brody, an associate professor of molecular biology affiliated with the Princeton Neuroscience Institute and a Howard Hughes Medical Institute Investigator....
Click here for more information.
Making decisions involves a gradual accumulation of facts that support one choice or another. A person choosing a college might weigh factors such as course selection, institutional reputation and the quality of ...
Researchers from North Carolina State University believe they have solved a puzzle that has vexed science since plants first appeared on Earth.
In a groundbreaking paper published online this week in Proceedings of the National Academy of Sciences, the researchers provide the first three-dimensional model of an enzyme that links a simple sugar, glucose, into long-chain cellulose, the basic building block within plant cell walls that gives plants structure. Cellulose is nature's most abundant renewable biomaterial and an important resource for production of biofuels that ...
AURORA, Colo. (April 15, 2013) – Researchers at the Linda Crnic Institute for Down Syndrome and the University of Colorado School of Medicine have found that a single mechanism may underlie the damaging effect of cholesterol on the brain and on blood vessels.
High levels of blood cholesterol increase the risk of both Alzheimer's disease and heart disease, but it has been unclear exactly how cholesterol damages the brain to promote Alzheimer's disease and blood vessels to promote atherosclerosis.
Using insights gained from studying two much rarer disorders, Down Syndrome ...
Projections of rainfall changes from global warming have been very uncertain because scientists could not determine how two different mechanisms will impact rainfall. The two mechanisms turn out to complement each other and together shape the spatial distribution of seasonal rainfall in the tropics, according to the study of a group of Chinese and Hawaii scientists that is published in the April 14, 2013, online issue of Nature Geoscience.
The one mechanism, called "wet-gets-wetter," predicts that rainfall should increase in regions that already have much rain, with a ...
Raising tobacco prices is one of the most effective means of reducing tobacco use, particularly among price-sensitive smokers such as young people and people with low incomes. But when the UK government has been raising cigarette taxes to increase prices and deter smoking, tobacco companies have been absorbing the tax increases on their ultra-low-price (ULP) brands to keep their prices low. As a result, real ULP cigarette prices have remained virtually unchanged since 2006 and their market share has doubled, suggesting that as cigarette taxes rise, many smokers downtrade ...
