DJ‐1 forms complexes with mutant SOD1 and ameliorates its toxicity

Abstract

Mutations in Cu/Zn superoxide dismutase (SOD1) gene cause familial amyotrophic lateral sclerosis (ALS), which could be attributed to the toxic properties of the misfolded protein, oxidative stress, and mitochondrial dysfunction. DJ-1 -a causative agent of familial Parkinson's disease PARK7 -is responsible for inducing antioxidative reaction. In this study, we showed the up-regulation of DJ-1 protein levels in mutant SOD1 transgenic mice through the lifespan were observed in the motor neurons. We demonstrated biochemically DJ-1 formed complexes with mutant SOD1 in the cell lysates. Furthermore, DJ-1 over-expression resulted in increased cell viability and reduced cell toxicity in mutant SOD1-transfected neuronal cells, because of improvement in apoptotic pathway and reduction in oxidative stress levels. We also evaluated DJ-1 levels in CSF collected from sporadic ALS patients and controls subjects. The CSF DJ-1 levels were significantly higher in patients with sporadic ALS than in control subjects. These results show that DJ-1 may be associated with sporadic and familial ALS pathogenesis. Therefore, insight into the effects of DJ-1 on mutant SOD1-mediated toxicity may provide a therapeutic advance for the treatment of motor neuron degeneration in ALS. Keywords: amyotrophic lateral sclerosis, antiapoptotic pathway, CSF, Cu/Zn superoxide dismutase, DJ-1, oxidative stress. Therefore, we hypothesized that DJ-1 could be expressed and play a protective role against cell stress, including oxidative stress in motor neurons in mice, and that DJ-1 might also protect motor neurons from the toxicity related to mutant SOD1. Lev et al. (2008) reported that up-regulation of DJ-1 mRNA and protein levels in the brains and spinal cords of FALS mice although they did not mention the location of up-regulation of DJ-1. In the present study, we showed that the up-regulation of DJ-1 protein levels in mutant SOD1 transgenic mice through the lifespan were observed in the motor neurons. Next, using biochemical methods, we demonstrated that DJ-1 formed complexes with mutant SOD1 in the cell lysates. Furthermore, we showed that DJ-1 over-expression resulted in increased cell viability and reduced cell toxicity in a mutant SOD1-transfected neuronal cell line because of the improved apoptotic pathway and reduction of oxidative stress. ELISA revealed that CSF DJ-1 levels were significantly higher in patients with SALS than in control subjects. Materials and methods AnimalsTransgenic mice carrying a high copy number of a mutant allele human SOD1 (G93A) gene (B6SJL-TgN [SOD1-G93A]1Gur) (Gurney et al. 1994) and their wild-type non-transgenic (NTG) littermates (B6SJL) were purchased from the Jackson Laboratory (Bar Harbor, ME, USA). Genotype analysis of the SOD1 mutation was performed by PCR with a set of primers, as described by Rosen et al. (1993) All animal research was approved by the Kumamoto University Committee on Animal Research. Construction of the expression vectorsThe cDNAs of hSOD1G93A , and hSOD1 G85R were amplified by PCR us...

DJ-1 Is a Copper Chaperone Acting on SOD1 Activation

“…Through pull-down assays, Yamashita et al (15) have already suggested the existence of a direct interaction between DJ-1 and SOD1. They showed the formation of complexes of mutant SOD1 and DJ-1 in mice primary motor neuron cultures.…”

“…Multiple literature reports underline the indisputable co-participation of DJ-1 and copper-zinc superoxide dismutase (Cu 2 Zn 2 ⅐SOD1 or SOD1) 2 in the complex pathways of cellular oxidative stress response (14,15). In vivo, SOD1 is the first line of defense against reactive oxygen species, scavenging superoxide radicals (16).…”

Sporadic juvenile amyotrophic lateral sclerosis caused by mutant FUS/TLS: possible association of mental retardation with this mutation

“…Although neuropathological analysis of such patients with ALS-FUS/TLS has not been performed yet, ALS-FUS/TLS might affect broader neuroanatomical regions than expected. Twenty-four hours after transfection, immunofluorescence analyses were performed on 4% paraformaldehyde-fixed cells according to a previously reported protocol [20] using mouse anti-FLAG (1:1000;…”

Sporadic Parkinson disease and Amyotrophic Lateral Sclerosis complex (Brait–Fahn–Schwartz Disease)

“…Recently, a PD-ALS syndrome with dementia has been described to be associated with mutations of DJ-1 (Park-7), a gene causing earlyonset PD [8]. This oncogene protein is widely expressed in CNS and it plays a neuroprotective role mitochondria-mediated against oxidative stress in PD and ALS models [20,21]. Thus, there is increasing evidence that PD and ALS may share a common pathogenesis in a subgroup of patients.…”