A short circuit in how cells digest and recycle damaged proteins could trigger the symptoms of Parkinson's, U.S. researchers said in a finding that could lead to new tretments for the incurable disease.

 

The team focused on a process called autophagy in which cells digest and recycle damaged molecules, including proteins, that develop as cells grow older. This system essentially renews cells to keep them functioning properly.

 

This mechanism is also important for nerve cells in the brain where defective proteins can kill cells and cause the debilitating symptoms of Parkinson's, such as tremors, said Ana Maria Cuervo, a cell biologist who led the study.

 

"We have found in Parkinson's there are problems in removing abnormal proteins," said Cuervo of the Albert Einstein College of Medicine of Yeshiva University.

 

The finding could lead to drugs to treat the symptoms but not cure the disease, which affects more than a million patients in the United States alone and is marked by the death of brain cells that produce dopamine. Dopamine is a neurotransmitter, or message-carrying chemical, associated with movement.

 

Cuervo had previously shown how mutant forms of a protein called alpha-synuclein -- found in a tiny percentage of Parkinson's patients -- blocked the breakdown of substances and prevented cells from clearing damaged proteins.

 

In the study in The Journal of Clinical Investigation on Wednesday, the team showed how in the majority of patients dopamine modifies normal proteins to act like the mutated ones to trigger tremors and other symptoms.

 

Cuervo said a drug to fix the breakdown in Parkinson's patients was years away because it would take researchers time to understand fully how the process worked.

 

(Xinhua News Agency January 3, 2008)