While scientists already knew that the enzyme known as Pin1 can prevent the tangles of knotlike brain lesions associated with Alzheimer's, new research, published in the March 23 issue of Nature, finds the enzyme also plays a pivotal role in guarding against a second type of lesion, the buildup of plaque, or flat deposits on the surface of brain cells. Alzheimer's is caused by the two types of lesions, or alterations in brain tissue, occurring simultaneously.

Researchers at Cornell University, Beth Israel Deaconess Medical Center (BIDMC) and Harvard Medical School authored the study.

"The new finding provides a very specific molecular interaction that can be used as a target in drug discovery," said Linda Nicholson, co-principal investigator on the study and a Cornell associate professor of molecular biology and genetics.

Nicholson and her Cornell team observed Pin1 acting on a protein called amyloid precursor protein (APP), which appears to be the primary cause of Alzheimer's. When APP gets a phosphate group attached to its tail (a process called phosphorylation), it toggles slowly back and forth between two forms. Like a kind of molecular Dr. Jekyll and Mr. Hyde, one form leads to buildup of plaque and disease, while the other form is part of normal function and helps neurons grow and survive.

Using a powerful microscopic technique called nuclear magnetic resonance spectroscopy, Nicholson and colleagues found that Pin1 acts as a kind of molecular accelerator, allowing APP to toggle back and forth between its good and bad forms 1,000 times faster than if Pin1 were not present. In the absence of Pin1, the Hyde-like, disease-causing form of APP has a chance to build up to high levels toxic to cells, which leads to plaque les
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Contact: Blaine Friedlander Jr.
bpf2@cornell.edu
607-254-8093
Cornell University News Service
29-Mar-2006