Parkinsonism associated deglycase
The PARK7 gene provides instructions for making the DJ-1 protein. This protein is found in many tissues and organs, including the brain. Studies indicate that the DJ-1 protein has several functions, although none are fully understood. One of the protein's functions may be to help protect cells, particularly brain cells, from oxidative stress. Oxidative stress occurs when unstable molecules called free radicals accumulate to levels that can damage or kill cells. Additionally, the DJ-1 protein may serve as a chaperone molecule that helps fold newly produced proteins into the proper 3-dimensional shape and helps refold damaged proteins. Like other chaperone molecules, the DJ-1 protein may assist in delivering selected proteins to proteasomes, which are structures within cells that break down unneeded molecules. Researchers suggest that the DJ-1 protein may also play a role in activities that produce and process RNA, a chemical cousin of DNA.
Researchers have identified more than 25 PARK7 gene mutations that can cause Parkinson disease, a condition characterized by progressive problems with movement and balance. These mutations are associated with the early-onset form of the disorder, which begins before age 50. Some PARK7 gene mutations lead to an abnormally small DJ-1 protein or change the building blocks (amino acids) used to make the protein. The altered protein is unstable and does not function properly, if at all. Other mutations delete a large portion of the PARK7 gene, preventing the production of any functional DJ-1 protein.
It is unclear how loss of functional DJ-1 protein leads to Parkinson disease. Some studies suggest that PARK7 gene mutations disrupt the protein's chaperone function, which leads to a toxic buildup of misfolded or damaged proteins and eventually to cell death. Another possibility is that PARK7 gene mutations impair the protein's ability to protect cells from destructive oxidative stress. Nerve cells that make the chemical messenger dopamine are particularly vulnerable to oxidative stress. With diminished protection, free radicals may cause enough damage to kill these nerve cells. Progressive loss of dopamine-producing nerve cells is a characteristic feature of Parkinson disease. The death of these cells weakens communication between the brain and muscles, and ultimately the brain becomes unable to control muscle movement.