In certain people with Parkinson's disease, mutations in the parkin gene disrupt the proper function of dopamine, the brain chemical that controls body movement.
The finding could lead to new treatments and screening methods for the disease, according to the University at Buffalo researchers.
Using live human neurons in the laboratory, the team found that parkin mutations hinder the actions of dopamine and produce more "free radicals," harmful molecules that destroy dopamine-laden brain cells, leading to Parkinson's disease.
"Once parkin is mutated, it can no longer precisely control the action of dopamine, which supports the neural computation required for our movement," study author Jian Feng, a professor of physiology and biophysics in the university's School of Medicine and Biomedical Sciences, said in a university news release.
The parkin mutation is responsible for only a small percentage of Parkinson's disease cases, Feng stressed. Nevertheless, understanding how parkin works is relevant to all Parkinson's patients, he said.
One expert agreed that the finding may not be of direct help to most Parkinson's patients at this time.
"One should be cautious in overstating the importance of this since most cases of idiopathic [arising from unknown cause] Parkinson's disease are not caused by parkin mutations," explained Dr. Andrew Feigin, director of the experimental therapeutics division of the Center for Neurosciences at The Feinstein Institute for Medical Research in Manhasset, N.Y. However, he added that, "the creation of human neurons containing a parkin mutation may provide a new means for screening potential therapies for Parkinson's disease."
The study appears in the current issue of the journal Nature Communications.
The researchers said this is the first study to use live human neurons to investigate the role that parkin plays in Parkinson's disease, and it was made possible by the use of stem cells.
The research team created human neurons using human skin cells taken from four people: two with a rare type of Parkinson's disease in which their disease is caused by the parkin mutation, and two with healthy people who served as controls.
There is no cure for Parkinson's disease, which affects at least 500,000 people in the United States.
Andrew Feigin, M.D., director, experimental therapeutics division, Center for Neurosciences, The Feinstein Institute for Medical Research, Manhasset, N.Y.; University at Buffalo, news release, Feb. 7, 2012