How small molecule can take apart Alzheimer's disease protein fibersMay 16, 2008PHILADELPHIA - Researchers from the University of Pennsylvania School of Medicine have shown, in unprecedented detail, how a small molecule is able to selectively take apart abnormally folded protein fibers connected to Alzheimer's disease and prion diseases. The findings appear online this week in the Proceedings of the National Academy of Sciences. Finding a way to dismantle misfolded proteins has implications for new treatments for a host of neurodegenerative diseases. Abnormal accumulation of amyloid fibers and other misfolded forms in the brain cause neurodegenerative diseases. Similarly, build-up of abnormally folded prion proteins between neurons causes the human version of mad cow disease, Creutzfeldt-Jakob disease. "Surprisingly, a small molecule called DAPH selectively targets the areas that hold fibers together, and converts fibers to a form that is unable to grow. Normally fibers grow from their ends, but the drug stops this activity," says senior author James Shorter, PhD, Assistant Professor of Biochemistry and Biophysics. "Our data suggest that it is possible to generate effective small molecules that can attack amyloid fibers, which are associated with so many devastating diseases." The researchers are now working on how DAPH acts as a wedge to stop the fibers from growing. "Presumably DAPH fits very neatly into the crevices between fiber subunits," explains Shorter. "When we grow yeast cells with the prion in the presence of DAPH, they begin to lose the prion. We also saw this in the test tube using pure fibers. The small molecule directly remodels fiber architecture. We've really been able to get at the mechanism by which DAPH, or any small molecule, works for the first time." DAPH was originally found in a screen of small molecules that reduce amyloid-beta toxicity in the lab of co-author Vernon Ingram, Shorter's collaborator at the Massachusetts Institute of Technology (MIT). In a test tube, if a small amount of amyloid or prion fiber is added to the normal form of the protein, it converts it to the fiber form. But when DPAH is added to the mix, the yeast prion protein does not aggregate into fibers. "It's essentially stopping fiber formation in its tracks," says Huan Wang, first author and research specialist in Shorter's lab. "We were surprised to see two very different proteins, amyloid-beta and Sup35, sensitive to this same small molecule." The next step is to identify more potent DAPH variants with greater selectivity for deleterious amyloids. Since some amyloids may turn out to be beneficial - for example, one form may be involved in long-term memory formation - it will be necessary to find a drug that does not hit all amyloids indiscriminately. "We'd need one that hits only problem amyloids, and DAPH gives us a hint that such selectivity is possible" says Shorter. University of Pennsylvania School of Medicine |
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| Related Prion Current Events and Prion News Articles Prion study reveals first direct information about the protein's molecular structure A collaboration between scientists at Vanderbilt University and the University of California, San Francisco has led to the first direct information about the molecular structure of prions. U of T led research team uncovers evolutionary origins of prion disease gene A University of Toronto-led team has uncovered the evolutionary ancestry of the prion gene, which may reveal new understandings of how the prion protein causes diseases such as bovine spongiform encephalopathy (BSE), also known as "mad cow disease." Species barrier may protect macaques from chronic wasting disease Data from an ongoing multi-year study suggest that people who consume deer and elk with chronic wasting disease (CWD) may be protected from infection by an inability of the CWD infectious agent to spread to people. A Penny for Your Prions North Carolina State University researchers have discovered a link between copper and the normal functioning of prion proteins, which are associated with transmissible spongiform encephalopathy diseases such as Cruetzfeldt-Jakob in humans or "mad cow" disease in cattle. Scripps Florida scientists devise accelerated method to determine infectious prion strainsScripps Florida scientists devise accelerated method to determine infectious prion strains Current tests to identify specific strains of infectious prions, which cause a range of transmissible diseases (such as mad cow) in animals and humans, can take anywhere from six months to a year to yield results - a time-lag that may put human populations at risk. Prevalence of variant CJD agent in Britain remains uncertain First results from a large tissue survey in Britain of the agent that causes variant Creutzfeldt-Jakob disease (vCJD) are unable so far to establish that the prevalence is lower than that given by previous estimates, concludes a study published on bmj.com today. Redefining what it means to be a prion Whitehead Institute researchers have quintupled the number of identifiable prion proteins in yeast and have further clarified the role prions play in the inheritance of both beneficial and detrimental traits. Iron is involved in prion disease-associated neuronal demise Imbalance of iron homeostasis is a common feature of prion disease-affected human, mouse, and hamster brains, according to a new study by Dr. Neena Singh and colleagues at Case Western Reserve University School of Medicine, alongside collaborators from Creighton University. Prion discovery gives clue to control of mass gene expression The discovery in common brewer's yeast of a new, infectious, misfolded protein -- or prion -- by University of Illinois at Chicago molecular biologists raises new questions about the roles played by these curious molecules, often associated with degenerative brain diseases like "mad cow" and its human counterpart, Creutzfeldt-Jakob. Antibody key to treating variant CJD, scientists find Scientists at the University of Liverpool have determined the atomic structure of the 'binding' between a brain protein and an antibody that could be key to treating patients with diseases such as variant CJD. More Prion Current Events and Prion News Articles |
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