A MYSTERY protein that may be a major cause of the brain damage found in
Alzheimer鈥檚 disease has come to light.
Until now, the damage has been blamed on the build-up of amyloid plaques and
on intracellular 鈥渢angles鈥� of another protein called tau. To try to find out
more about these, a team led by John Trojanowski of University of Pennsylvania
made antibodies to diseased tissue from the brains of Alzheimer鈥檚 patients.
To their surprise, the researchers found that the antibodies grabbed hold of
a previously unknown protein. In this month鈥檚 issue of the American Journal
of Pathology the team reports that the new protein makes up as much as a
third of the diseased brain tissue in patients with Alzheimer鈥檚.
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鈥淚t occupies as much of the Alzheimer鈥檚 brain as amyloid plaques do,鈥� says
Trojanowski. 鈥淲e have every reason to suspect that this pathology plays a
crucial role in the development and progression of Alzheimer鈥檚.鈥�
The researchers speculate that the new protein, which they have called AMY,
has remained undetected until now because it does not show up in standard
laboratory tests. While the previously known proteins show up using staining
techniques, AMY does not.
After examining brains from many elderly patients the team found that all of
those with AMY plaques had at least some amyloid fibrils. However, brains
without AMY plaques contained no amyloid fibrils. The researchers suspect that
AMY plaques may lead to beta-amyloid deposition.