Mitochondrial localization of the Parkinson's disease related protein DJ-1: implications for pathogenesis

Abstract

Both homozygous (L166P, M26I, deletion) and heterozygous mutations (D149A, A104T) in the DJ-1 gene have been identified in Parkinson's disease (PD) patients. The biochemical function and subcellular localization of DJ-1 protein have not been clarified. To date the localization of DJ-1 protein has largely been described in studies over-expressing tagged DJ-1 protein in vitro. It is not known whether the subcellular localization of over-expressed DJ-1 protein is identical to that of endogenously expressed DJ-1 protein both in vitro and in vivo. To clarify the subcellular localization and function of DJ-1, we generated three highly specific antibodies to DJ-1 protein and investigated the subcellular localization of endogenous DJ-1 protein in both mouse brain tissues and human neuroblastoma cells. We have found that DJ-1 is widely distributed and is highly expressed in the brain. By cell fractionation and immunogold electron microscopy, we have identified an endogenous pool of DJ-1 in mitochondrial matrix and inter-membrane space. To further investigate whether pathogenic mutations might prevent the distribution of DJ-1 to mitochondria, we generated human neuroblastoma cells stably transfected with wild-type (WT) or mutant (M26I, L166P, A104T, D149A) DJ-1 and performed mitochondrial fractionation and confocal co-localization imaging studies. When compared with WT and other mutants, L166P mutant exhibits largely reduced protein level. However, the pathogenic mutations do not alter the distribution of DJ-1 to mitochondria. Thus, DJ-1 is an integral mitochondrial protein that may have important functions in regulating mitochondrial physiology. Our findings of DJ-1's mitochondrial localization may have important implications for understanding the pathogenesis of PD.

RNA binding activity of the recessive parkinsonism protein DJ-1 supports involvement in multiple cellular pathways

“…The mitochondrial transcripts are also of interest because of the emerging evidence of a mitochondrial basis of recessive parkinsonism (2, 3). DJ-1 can be found on the surface of mitochondria (6) and within the mitochondrial matrix (28), supporting the idea that a small pool of DJ-1 may authentically associate with RNA in the mitochondria. However, this hypothesis requires additional confirmation.…”

Revisiting oxidative stress and mitochondrial dysfunction in the pathogenesis of Parkinson disease—resemblance to the effect of amphetamine drugs of abuse

“…DJͲ1 gene encodes a protein of 189 amino acids, belonging to the peptidase C56 family of proteins [263]. It is a cytoplasmic protein, but under stress conditions can also translocate into the mitochondria and nucleus [146,264]. WT DJͲ1 appears to exert an antioxidant function [265Ͳ268], while deletions and point mutations in the DJͲ1 gene cause a loss of its physiological function and therefore, lead to neurodegeneration in rare families [146, 269Ͳ271].…”

Stimulation of vesicular monoamine transporter 2 activity by DJ-1 in SH-SY5Y cells

“…Furthermore, we have reported that DJ-1 activated TH and DDC through direct binding to TH and DDC in an oxidative status of DJ-1-dependent manner [24] and that human DJ-1 activates TH gene expression in cultured human dopaminergic cells [15]. DJ-1 is preferentially localized in the cytoplasm and nucleus [7] and a portion of DJ-1 is localized in the mitochondria [22,[25][26][27] and synapse [28].…”