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Thursday, 24 May, 2001, 17:48 GMT 18:48 UK
Brain diseases discovery
Protein clumps in the brain are linked to Alzheimer's

Scientists have made a breakthrough that could lead to new treatments for Alzheimer's disease and other neurological conditions.

The work appears to prove that these diseases are caused, at least in part, by mysterious clumps of defective beta amyloid proteins that build up in the brain.

It has long been known that these clumps disrupt the function of nerve cells. But it was unclear whether the clumps caused disease, or were a by-product of it.

US researchers from the University of Sandford have shown that the former is true.

Master enzyme

They have proved a link between the accumulation of the protein clumps and a "master" enzyme found in cells called a proteasome.

The proteasome effectively cleans cells by disposing of unwanted and abnormal proteins.

However, the Sandford scientists showed that if abnormal proteins start to clump together, this neutralises the ability of proteasome to keep the cell clean.

In turn, this leads to ever more clumping of abnormal protein.

The build up of protein clumps in nerve cells appears to be gradual, and the scientists believe that may explain why diseases like Alzheimer's usually do not become apparent until later in life.

They produced cells which glowed green under UV light when the proteasome mechanism was not working.

When genes associated with Huntingdon's disease were inserted into the cells, they turned bright green in a matter of hours, and began to fill with protein clumps.

Second study

A similar conclusion was reached in a separate study on mice by US and Japanese scientists from the RIKEN Brain Science Institute in Wako-shi, Japan, and Harvard University Medical School in Boston, Massachusetts.

Their work suggests that it might be more effective to destroy protein clumps once they have formed, rather to try to prevent their formation in the first place.

The researchers found that even a small drop in the activity of another natural enzyme - such as that which might occur naturally with ageing - that breaks down the protein clusters led to a significant increase in their formation.

They suggested that it might be possible to develop a new treatment based on boosting the activity of this enzyme, neprilysin.

Dr Donald Lehmann, of the Alzheimer's Research Trust, said a number of important questions remained to be answered.

"Will neprilysin prove as important in human brain as it evidently is in mice?  What side-effects will result from increasing the activity of this powerful enzyme?  Most important, how central is beta amyloid to Alzheimer's?  Will blocking its accumulation prevent the disease?"

Both studies are published in the journal Science.

See also:

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