Cholesterol May Play a Role in Alzheimer's Disease
by Alisa Machalek, NIGMS
Scientists have long known that cholesterol plays a number of roles—both good and bad—in the body. Now, they suspect it might also contribute to the development of Alzheimer's disease.
A team of researchers at Vanderbilt University Medical Center in Nashville, Tennessee, used laboratory-made membranes and structural biology techniques to examine how this might happen.
The scientists, led by Charles Sanders, proved that cholesterol can hook up with a protein called APP in the synthesized membranes. Based on other studies, the researchers believe that cholesterol then drives APP into crowded areas of membranes known as lipid rafts. There, enzymes hack off pieces of APP, transforming it into a substance called amyloid beta. Long linked with Alzheimer's, amyloid beta accumulates in the brains of those with the disease.
The Vanderbilt scientists propose that this process leads to Alzheimer's. If so, a drug that prevents cholesterol from connecting to APP might forestall the disease. Such a drug would require many years to develop and test. But, if successful, it might be the first therapy to prevent a condition that affects up to 5 million people in the U.S.
Enzyme Could Heal Sun Damage
by Jilliene Mitchell, NIGMS
Too much sun makes your skin wrinkled, burned, and leathery. It also damages your DNA, increasing your risk for cancer. Plants and many animals have an enzyme called photolyase that can repair sun damage. Humans lack it.
Recent studies revealing the workings of photolyase provide a ray of hope for preventing or treating sun damage in people. The research was led by Dongping Zhong, a physicist and chemist at Ohio State University in Columbus.
The scientists first exposed a strand of DNA to ultraviolet (UV) light, causing the same kind of damage as the sun. Then they added photolyase. Using an ultrafast laser as a sort of high-tech flashbulb, they were able to see photolyase in action as it repaired the UV-damaged DNA.
Zhong's group discovered that photolyase sends an electron and a proton to repair the damaged genetic material. After this process, the electron and proton return to the enzyme—possibly to start over and heal other areas.
More research on photolyase might lead to new treatments for skin cancer and better sunscreen products.
"For the past five decades, scientists supported by the National Institute of General Medical Sciences have made discoveries that led to medical advances.."
by Alison Davis, NIGMS
All animals sleep, including flies. Like us, these insects need more sleep if deprived of it; they perk up with caffeine, and their primitive brains have small electrical surges while they snooze.
However, unlike people, flies breed quickly, and since researchers have a detailed knowledge of their genetics and behavior, flies are an ideal model system for studying biology. Scientists are using fruit flies to find out why we sleep—and what happens when we do.
Neuroscientists Chiara Cirelli and Giulio Tononi of the University of Wisconsin- Madison have concluded that sleep refreshes nerve cell connections that become overworked while we are awake.
They found that levels of proteins in synapses—the working ends of nerve cells— plummet at night in well-rested flies, presumably clearing away excess "noise" built up during the preceding day.
The scientists reason that the molecular housecleaning that takes place during sleep readies the brain for learning and allows it to save energy. If proven true in humans, the results could deepen understanding about insomnia and other sleep disorders.
A New View of the Flu
by Kirstie Saltsman, NIGMS
If you've ever gotten the flu, you know that we don't have many drugs to treat it. New information from scientists studying one antiflu medicine, amantadine, may pave the way for designing more such drugs.
Biophysicists Mei Hong at Iowa State University and William DeGrado at the University of Pennsylvania discovered how amantadine interacts with a flu protein called M2. This protein launches infection by creating a channel between the flu virus and a healthy cell.
When the researchers determined the detailed, 3-D structure of amantadine bound to M2, they revealed that the drug plugs this channel, preventing infection. They also noticed that amantadine fits loosely inside M2, possibly leaving room for altered versions of the protein to wiggle free and go on to infect a cell. If virus particles containing this version of M2 multiplied, they could lead to a drug-resistant strain.
Already, many strains of the flu resist treatment by amantadine. The biophysicists think that designing drugs that fit into M2 more tightly than amantadine does could provide an effective treatment for the flu that is more difficult for the virus to resist.
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