Progressive loss of motor control due to reduction of dopamine producing neurons in the substantia nigra pars compacta and decreased striatal dopamine levels are the classically described features of Parkinsons disease (PD). Neuronal damage progresses also to other regions of the brain and additional non-motor dysfunctions are common. Accumulation of environmental toxins, such as pesticides and metals, are suggested risk factors for the development of typical, late onset PD, while genetic factors seem to be substantial in early onset cases. Mutations of DJ-1 are known to cause a form of recessive early onset Parkinsons disease, highlighting an important functional role for DJ-1 in early disease prevention. This study identifies human DJ-1 as a metal binding protein able to bind copper as well as toxic mercury ions in vitro. The study further characterizes the cytoprotective function of DJ-1 and PD mutated variants of DJ-1, in respect to induced metal cytotoxicity. The results show that expression of DJ-1 enhances the cells protective mechanisms against induced metal toxicity, and that this protection is lost for DJ-1 PD mutations; A104T and D149A. The study also shows that oxidation site mutated DJ-1 C106A retains its ability to protect cells. We also show that concomitant addition of dopamine exposure sensitizes cells to metal induced cytotoxicity. We also confirm that redox-active dopamine adducts enhances metal-catalyzed oxidation of intracellular proteins in vivo by use of live-cell imaging of redox sensitive S3roGFP. The study indicate that even a small genetic alteration can sensitise cells to metal induced cell death, a finding that may revive the interest in exogenous factors in the etiology of PD.
PMID: 23792957 [PubMed - as supplied by publisher]