PARK7/DJ-1 deficiency impairs microglial activation in response to LPS-induced inflammation.

BACKGROUND: Specific microglia responses are thought to contribute to the development and progression of neurodegenerative diseases, including Parkinson's disease (PD). However, the phenotypic acquisition of microglial cells and their role during the underlying neuroinflammatory processes remain largely elusive. Here, according to the multiple-hit hypothesis, which stipulates that PD etiology is determined by a combination of genetics and various environmental risk factors, we investigate microglial transcriptional programs and morphological adaptations under PARK7/DJ-1 deficiency, a genetic cause of PD, during lipopolysaccharide (LPS)-induced inflammation. METHODS: Using a combination of single-cell RNA-sequencing, bulk RNA-sequencing, multicolor flow cytometry and immunofluorescence analyses, we comprehensively compared microglial cell phenotypic characteristics in PARK7/DJ-1 knock-out (KO) with wildtype littermate mice following 6- or 24-h intraperitoneal injection with LPS. For translational perspectives, we conducted corresponding analyses in human PARK7/DJ-1 mutant induced pluripotent stem cell (iPSC)-derived microglia and murine bone marrow-derived macrophages (BMDMs). RESULTS: By excluding the contribution of other immune brain resident and peripheral cells, we show that microglia acutely isolated from PARK7/DJ-1 KO mice display a distinct phenotype, specially related to type II interferon and DNA damage response signaling, when compared with wildtype microglia, in response to LPS. We also detected discrete signatures in human PARK7/DJ-1 mutant iPSC-derived microglia and BMDMs from PARK7/DJ-1 KO mice. These specific transcriptional signatures were reflected at the morphological level, with microglia in LPS-treated PARK7/DJ-1 KO mice showing a less amoeboid cell shape compared to wildtype mice, both at 6 and 24 h after acute inflammation, as also observed in BMDMs. CONCLUSIONS: Taken together, our results show that, under inflammatory conditions, PARK7/DJ-1 deficiency skews microglia towards a distinct phenotype characterized by downregulation of genes involved in type II interferon signaling and a less prominent amoeboid morphology compared to wildtype microglia. These findings suggest that the underlying oxidative stress associated with the lack of PARK7/DJ-1 affects microglia neuroinflammatory responses, which may play a causative role in PD onset and progression.

Protein deglycase DJ-1 deficiency induces phenotypic switching in vascular smooth muscle cells and exacerbates atherosclerotic plaque instability.

Protein deglycase DJ-1 (DJ-1) is a multifunctional protein involved in various biological processes. However, it is unclear whether DJ-1 influences atherosclerosis development and plaque stability. Accordingly, we evaluated the influence of DJ-1 deletion on the progression of atherosclerosis and elucidate the underlying mechanisms. We examine the expression of DJ-1 in atherosclerotic plaques of human and mouse models which showed that DJ-1 expression was significantly decreased in human plaques compared with that in healthy vessels. Consistent with this, the DJ-1 levels were persistently reduced in atherosclerotic lesions of ApoE-/- mice with the increasing time fed by western diet. Furthermore, exposure of vascular smooth muscle cells (VSMCs) to oxidized low-density lipoprotein down-regulated DJ-1 in vitro. The canonical markers of plaque stability and VSMC phenotypes were evaluated in vivo and in vitro. DJ-1 deficiency in Apoe-/- mice promoted the progression of atherosclerosis and exaggerated plaque instability. Moreover, isolated VSMCs from Apoe-/- DJ-1-/- mice showed lower expression of contractile markers (α-smooth muscle actin and calponin) and higher expression of synthetic indicators (osteopontin, vimentin and tropoelastin) and Kruppel-like factor 4 (KLF4) by comparison with Apoe-/- DJ-1+/+ mice. Furthermore, genetic inhibition of KLF4 counteracted the adverse effects of DJ-1 deletion. Therefore, our results showed that DJ-1 deletion caused phenotype switching of VSMCs and exacerbated atherosclerotic plaque instability in a KLF4-dependent manner.

Anesthetic Effects on the Progression of Parkinson Disease in the Rat DJ-1 Model.

BACKGROUND: Parkinson disease is a chronic and progressive movement disorder characterized by the loss of dopaminergic neurons in the substantia nigra pars compacta (SNpc). The causes of Parkinson disease are not clear but may involve genetic susceptibilities and environmental factors. As in other neurodegenerative disorders, individuals predisposed to Parkinson disease may have an accelerated onset of symptoms following perioperative stress such as anesthesia, surgery, pain, and inflammation. We hypothesized that anesthesia alone accelerates the onset of Parkinson disease-like pathology and symptoms. METHODS: A presymptomatic Parkinson rat model (the protein, DJ-1, encoded by the Park7 gene [DJ-1], PARK7 knockout) was exposed to a surgical plane of isoflurane or 20% oxygen balanced with nitrogen for 2 hours on 3 occasions between 6 and 7 months of age. Acute and long-term motor and neuropathological effects were examined from 7 to 12 months of age in male DJ-1 rats, using the ladder rung, rotarod, and novel object recognition assays, as well as the immunohistochemical localization of tyrosine hydroxylase in dopaminergic neurons in the substantia nigra and ionized calcium-binding adaptor protein-1 (Iba-1) microglial activation in the substantia nigra and hippocampus. RESULTS: In the acute group, after the third anesthetic exposure at 7 months of age, the isoflurane group had a significant reduction in the density of dopaminergic neurons in the SNpc compared to controls. However, this reduction was not associated with increased microglial activation in the hippocampus or substantia nigra. With the ladder rung motor skills test, there was no effect of anesthetic exposure on the total number of foot faults or the ladder rung pattern in the acute group. The rotarod test also detected no differences before and after the third exposure in controls. For the long-term group, immunohistochemical analyses detected no differences in the density of dopaminergic neurons or microglial cells compared to unexposed DJ-1 rats from 8 to 12 months of age. The ladder rung test in the long-term group showed no differences in the total number of foot faults with time and exposure or between ladder rung patterns. The rotarod test detected no significant effect of exposure with time or between groups at any time point. The novel object recognition task in the long-term group revealed no differences in short- or long-term memory or in the number of rearings as a function of exposure. CONCLUSIONS: Multiple isoflurane exposures in this rat model of Parkinson disease transiently enhanced dopaminergic neurodegeneration in the SNpc that resolved over time and had no effects on progression in this Parkinson disease-like phenotype.

Critical roles of astrocytic-CCL2-dependent monocyte infiltration in a DJ-1 knockout mouse model of delayed brain repair.

Monocyte-derived macrophages play a role in the repair of the injured brain. We previously reported that a deficiency of the Parkinson's disease (PD)-associated gene DJ-1 delays repair of brain injury produced by stereotaxic injection of ATP, a component of damage-associated molecular patterns. Here, we show that a DJ-1 deficiency attenuates monocyte infiltration into the damaged brain owing to a decrease in C-C motif chemokine ligand 2 (CCL2) expression in astrocytes. Like DJ-1-knockout (KO) mice, CCL2 receptor (CCR2)-KO mice showed defects in monocyte infiltration and delayed recovery of brain injury, as determined by 9.4 T magnetic resonance imaging analysis and immunostaining for tyrosine hydroxylase and glial fibrillary acid protein. Notably, transcriptome analyses showed that genes related to regeneration and synapse formation were similarly downregulated in injured brains of DJ-1-KO and CCR2-KO mice compared with the injured wild-type brain. These results indicate that defective astrogliosis in DJ-1-KO mice is associated with decreased CCL2 expression and attenuated monocyte infiltration, resulting in delayed repair of brain injury. Thus, delayed repair of brain injury could contribute to the development of PD. MAIN POINTS: A DJ-1 deficiency attenuates infiltration of monocytes owing to a decrease in CCL2 expression in astrocytes, which in turn led to delay in repair of brain injury.

DJ-1 deficiency causes metabolic abnormality in ornidazole-induced asthenozoospermia.

Asthenozoospermia (AS), defined as low-motility spermatozoa in the ejaculate, is a frequent cause of human male infertility. DJ-1 (also known as PARK7), a protein highly associated with male sterility, binds to the mitochondrial complex I subunit to protect mitochondrial function. However, its involvement in spermatogenesis has not been fully elucidated. Previously, the levels of DJ-1 were shown to be significantly decreased in testicular tissues of rats with ornidazole (ORN)-induced AS. Here, we used a rat model to investigate the localization and expression levels of DJ-1 and its interacting NDUFS3 and NDUFA4 mitochondrial complex I subunits, as well as AS-induced metabolic alterations in testicular tissues. ORN significantly reduced the levels of DJ-1 in the nucleus of secondary spermatocytes, while increasing the expression of NDUFS3 in the cytoplasm of primary spermatocytes. Further, NDUFA4 showed higher expression after treatment with ORN. The principal ORN-induced changes in metabolic small molecules related to the accumulation of glucose, glutamine, and N-acetyl aspartate, enhancement of purine pathway, increase of the phosphatidic acid (PA) (18:0/18:1), phosphatidylethanolamine (PE) (16:0/18:1), and PA (18:0/20:4) lipid metabolites, and imbalance in the concentrations of Na+ and K+. However, we did not observe any abnormalities of certain small metabolic molecules and metal ions in semen samples from patients with AS. In conclusion, these results suggest that DJ-1 deficiency in testicular tissues might be closely related to the localization of NDUFS3 and content of NDUFA4, thus causing abnormalities in the mitochondrial energy metabolism and multiple other metabolic pathways.

The role of DJ-1 in human primary alveolar type II cell injury induced by e-cigarette aerosol.

The alveolus participates in gas exchange, which can be impaired by environmental factors and toxins. There is an increase in using electronic cigarettes (e-cigarettes); however, their effect on human primary alveolar epithelial cells is unknown. Human lungs were obtained from nonsmoker organ donors to isolate alveolar type II (ATII) cells. ATII cells produce and secrete pulmonary surfactant and restore the epithelium after damage, and mitochondrial function is important for their metabolism. Our data indicate that human ATII cell exposure to e-cigarette aerosol increased IL-8 levels and induced DNA damage and apoptosis. We also studied the cytoprotective effect of DJ-1 against ATII cell injury. DJ-1 knockdown in human primary ATII cells sensitized cells to mitochondrial dysfunction as detected by high mitochondrial superoxide production, decreased mitochondrial membrane potential, and calcium elevation. DJ-1 knockout (KO) mice were more susceptible to ATII cell apoptosis and lung injury induced by e-cigarette aerosol compared with wild-type mice. Regulation of the oxidative phosphorylation (OXPHOS) is important for mitochondrial function and protection against oxidative stress. Major subunits of the OXPHOS system are encoded by both nuclear and mitochondrial DNA. We found dysregulation of OXPHOS complexes in DJ-1 KO mice after exposure to e-cigarette aerosol, which could disrupt the nuclear/mitochondrial stoichiometry, resulting in mitochondrial dysfunction. Together, our results indicate that DJ-1 deficiency sensitizes ATII cells to damage induced by e-cigarette aerosol leading to lung injury.

A Parkinson's disease gene, DJ-1, repairs brain injury through Sox9 stabilization and astrogliosis.

Defects in repair of damaged brain accumulate injury and contribute to slow-developing neurodegeneration. Here, we report that a deficiency of DJ-1, a Parkinson's disease (PD) gene, delays repair of brain injury due to destabilization of Sox9, a positive regulator of astrogliosis. Stereotaxic injection of ATP into the brain striatum produces similar size of acute injury in wild-type and DJ-1-knockout (KO) mice. However, recovery of the injury is delayed in KO mice, which is confirmed by 9.4T magnetic resonance imaging and tyrosine hydroxylase immunostaining. DJ-1 regulates neurite outgrowth from damaged neurons in a non-cell autonomous manner. In DJ-1 KO brains and astrocytes, Sox9 protein levels are decreased due to enhanced ubiquitination, resulting in defects in astrogliosis and glial cell-derived neurotrophic factor/ brain-derived neurotrophic factor expression in injured brain and astrocytes. These results indicate that DJ-1 deficiency causes defects in astrocyte-mediated repair of brain damage, which may contribute to the development of PD.

Oxidative Stress Regulation and DJ-1 Function in the Retinal Pigment Epithelium: Implications for AMD.

In the retina, oxidative stress can initiate a cascade of events that ultimately leads to a focal loss of RPE cells and photoreceptors, a major contributing factor in geographic atrophy. Despite these implications, the molecular regulation of RPE oxidative metabolism under physiological and pathological conditions remains largely unknown. DJ-1 functions as an antioxidant, redox-sensitive molecular chaperone, and transcription regulator, which protected cells from oxidative stress. Here we discuss our progress toward characterization of the DJ-1 function in the protection of RPE to oxidative stress.

DJ-1/Park7 Sensitive Na+ /H+ Exchanger 1 (NHE1) in CD4+ T Cells.

DJ-1/Park7 is a redox-sensitive chaperone protein counteracting oxidation and presumably contributing to the control of oxidative stress responses and thus inflammation. DJ-1 gene deletion exacerbates the progression of Parkinson's disease presumably by augmenting oxidative stress. Formation of reactive oxygen species (ROS) is paralleled by activation of the Na+ /H+ exchanger 1 (NHE1). ROS formation in CD4+ T cells plays a decisive role in regulating inflammatory responses. In the present study, we explored whether DJ-1 is expressed in CD4+ T cells, and affects ROS production as well as NHE1 in those cells. To this end, DJ-1 and NHE1 transcript, and protein levels were quantified by qRT-PCR and Western blotting, respectively, intracellular pH (pHi ) utilizing bis-(2-carboxyethyl)-5-(and-6)-carboxyfluorescein (BCECF) fluorescence, NHE activity from realkalinization after an ammonium pulse, and ROS production utilizing 2',7' -dichlorofluorescin diacetate (DCFDA) fluorescence. As a result DJ-1 was expressed in CD4+ T cells. ROS formation, NHE1 transcript levels, NHE1 protein, and NHE activity were higher in CD4+ T cells from DJ-1 deficient mice than in CD4+ T cells from wild type mice. Antioxidant N-acetyl-cysteine (NAC) and protein tyrosine kinase (PTK) inhibitor staurosporine decreased the NHE activity in DJ-1 deficient CD4+ T cells, and blunted the difference between DJ-1-/- and DJ-1+/+ CD4+ T cells, an observation pointing to a role of ROS in the up-regulation of NHE1 in DJ-1-/- CD4+ T cells. In conclusion, DJ-1 is a powerful regulator of ROS production as well as NHE1 expression and activity in CD4+ T cells. J. Cell. Physiol. 232: 3050-3059, 2017. © 2016 Wiley Periodicals, Inc.

DJ-1 deficiency impairs autophagy and reduces alpha-synuclein phagocytosis by microglia.

Parkinson's disease (PD) is a progressive neurodegenerative disorder, of which 1% of the hereditary cases are linked to mutations in DJ-1, an oxidative stress sensor. The pathological hallmark of PD is intercellular inclusions termed Lewy Bodies, composed mainly of α-Synuclein (α-Syn) protein. Recent findings have shown that α-Syn can be transmitted from cell to cell, suggesting an important role of microglia, as the main scavenger cells of the brain, in clearing α-Syn. We previously reported that the knock down (KD) of DJ-1 in microglia increased cells' neurotoxicity to dopaminergic neurons. Here, we discovered that α-Syn significantly induced elevated secretion of the proinflammatory cytokines IL-6 and IL-1ß and a significant dose-dependent elevation in the production of nitric oxide in DJ-1 KD microglia, compared to control microglia. We further investigated the ability of DJ-1 KD microglia to uptake and degrade soluble α-Syn, and discovered that DJ-1 KD reduces cell-surface lipid raft expression in microglia and impairs their ability to uptake soluble α-Syn. Autophagy is an important mechanism for degradation of intracellular proteins and organelles. We discovered that DJ-1 KD microglia exhibit an impaired autophagy-dependent degradation of p62 and LC3 proteins, and that manipulation of autophagy had less effect on α-Syn uptake and clearance in DJ-1 KD microglia, compared to control microglia. Further studies of the link between DJ-1, α-Syn uptake and autophagy may provide useful insights into the role of microglia in the etiology of the PD.

DJ-1 activates autophagy in the repression of cardiac hypertrophy.

Cardiac hypertrophy is the risk factor of heart failure when the heart is confronted with pressure overload or neurohumoral stimuli. Autophagy, a conserved degradative pathway, is one of the important mechanisms involved in the regulation of cardiac hypertrophy. DJ-1 is a traditional anti-oxidative protein and emerging evidence suggested that DJ-1 might modulate autophagy. However, the regulation of autophagy by DJ-1 in the process of cardiac hypertrophy remains unknown. In our study, we firstly discovered that the expression of DJ-1declined in the process of pressure overload cardiac hypertrophy, and its alteration was parallel with the impairment of autophagy. Furthermore, we proved that DJ-1 knockout mice exhibited a more hypertrophied phenotype than wildtype mice in cardiac hypertrophy which indicated that DJ-1 is responsible for the repression of cardiac hypertrophy. Furthermore, DJ-1 knockout significantly exacerbated pulmonary edema due to cardiac hypertrophy. In the process of cardiac hypertrophy, DJ-1 knockout significantly impaired autophagy activation and enhanced mTORC1 and mTORC2 phosphorylation were found. Similarly, our in vitro study proved that DJ-1 overexpression ameliorated phenylephrine (PE)-induced cardiac hypertrophy and promoted autophagy activation. Taken together, DJ-1 might repress both pressure overload and PE-induced cardiac hypertrophy via the activation of autophagy.

DJ-1 protects the heart against ischemia-reperfusion injury by regulating mitochondrial fission.

Recent data indicates that DJ-1 plays a role in the cellular response to stress. Here, we aimed to examine the underlying molecular mechanisms mediating the actions of DJ-1 in the heart following myocardial ischemia-reperfusion (I/R) injury. In response to I/R injury, DJ-1 KO mice displayed increased areas of infarction and worsened left ventricular function when compared to WT mice, confirming a protective role for DJ-1 in the heart. In an effort to evaluate the potential mechanism(s) responsible for the increased injury in DJ-1 KO mice, we focused on SUMOylation, a post-translational modification process that regulates various aspects of protein function. DJ-1 KO hearts after I/R injury were found to display enhanced accumulation of SUMO-1 modified proteins and reduced SUMO-2/3 modified proteins. Further analysis, revealed that the protein expression of the de-SUMOylation enzyme SENP1 was reduced, whereas the expression of SENP5 was enhanced in DJ-1 KO hearts after I/R injury. Finally, DJ-1 KO hearts were found to display enhanced SUMO-1 modification of dynamin-related protein 1, excessive mitochondrial fission, and dysfunctional mitochondria. Our data demonstrates that the activation of DJ-1 in response to myocardial I/R injury protects the heart by regulating the SUMOylation status of Drp1 and attenuating excessive mitochondrial fission.

Regulation of DJ-1 by Glutaredoxin 1 in Vivo: Implications for Parkinson's Disease.

Parkinson's disease (PD) is the second most common neurodegenerative disease worldwide, caused by the degeneration of the dopaminergic neurons in the substantia nigra. Mutations in PARK7 (DJ-1) result in early onset autosomal recessive PD, and oxidative modification of DJ-1 has been reported to regulate the protective activity of DJ-1 in vitro. Glutathionylation is a prevalent redox modification of proteins resulting from the disulfide adduction of the glutathione moiety to a reactive cysteine-SH, and glutathionylation of specific proteins has been implicated in regulation of cell viability. Glutaredoxin 1 (Grx1) is the principal deglutathionylating enzyme within cells, and it has been reported to mediate protection of dopaminergic neurons in Caenorhabditis elegans; however many of the functional downstream targets of Grx1 in vivo remain unknown. Previously, DJ-1 protein content was shown to decrease concomitantly with diminution of Grx1 protein content in cell culture of model neurons (SH-SY5Y and Neuro-2A lines). In the current study we aimed to investigate the regulation of DJ-1 by Grx1 in vivo and characterize its glutathionylation in vitro. Here, with Grx(-/-) mice we provide show that Grx1 regulates protein levels of DJ-1 in vivo. Furthermore, with model neuronal cells (SH-SY5Y) we observed decreased DJ-1 protein content in response to treatment with known glutathionylating agents, and with isolated DJ-1 we identified two distinct sites of glutathionylation. Finally, we found that overexpression of DJ-1 in the dopaminergic neurons partly compensates for the loss of the Grx1 homologue in a C. elegans in vivo model of PD. Therefore, our results reveal a novel redox modification of DJ-1 and suggest a novel regulatory mechanism for DJ-1 content in vivo.

Growth hormone is increased in the lungs and enhances experimental lung metastasis of melanoma in DJ-1 KO mice.

BACKGROUND: Growth hormone (GH) mainly serves an endocrine function to regulate somatic growth, but also serves an autocrine function in lung growth and pulmonary function. Several recent studies have demonstrated the role of autocrine GH in tumor progression in some organs. However, it is not clear whether excessive secretion of GH in the lungs is related to pulmonary nodule formation. METHODS: Firstly, the lung tissues dissected from mice were used for Western blotting and PCR measurement. Secondly, the cultured cells were used for examining effects of GH on B16F10 murine melanoma cells. Thirdly, male C57BL/6 mice were intravenously injected with B16F10 cells and then subcutaneously injected with recombinant GH twice per week for three weeks. Finally, stably transfected pool of B16F10 cells with knockdown of growth hormone receptor (GHR) was used to be injected into mice. RESULTS: We found that expression of GH was elevated in the lungs of DJ-1 knockout (KO) mice. We also examined the effects of GH on the growth of cultured melanoma cells. The results showed that GH increased proliferation, colony formation, and invasive capacity of B16F10 cells. In addition, GH also increased the expression of matrix metalloproteinases (MMPs) in B16F10 cells. Administration of GH in vivo enhanced lung nodule formation in C57/B6 mice. Increased lung nodule formation in DJ-1 KO mice following intravenous injection of melanoma cells was inhibited by GHR knockdown in B16F10 cells. CONCLUSIONS: These results indicate that up-regulation of GH in the lungs of DJ-1 KO mice may enhance the malignancy of B16F10 cells and nodule formation in pulmonary metastasis of melanoma.

Loss of park7 activity has differential effects on expression of iron responsive element (IRE) gene sets in the brain transcriptome in a zebrafish model of Parkinson's disease.

Mutation of the gene PARK7 (DJ1) causes monogenic autosomal recessive Parkinson's disease (PD) in humans. Subsequent alterations of PARK7 protein function lead to mitochondrial dysfunction, a major element in PD pathology. Homozygous mutants for the PARK7-orthologous genes in zebrafish, park7, show changes to gene expression in the oxidative phosphorylation pathway, supporting that disruption of energy production is a key feature of neurodegeneration in PD. Iron is critical for normal mitochondrial function, and we have previously used bioinformatic analysis of IRE-bearing transcripts in brain transcriptomes to find evidence supporting the existence of iron dyshomeostasis in Alzheimer's disease. Here, we analysed IRE-bearing transcripts in the transcriptome data from homozygous park7-/- mutant zebrafish brains. We found that the set of genes with "high quality" IREs in their 5' untranslated regions (UTRs, the HQ5'IRE gene set) was significantly altered in these 4-month-old park7-/- brains. However, sets of genes with IREs in their 3' UTRs appeared unaffected. The effects on HQ5'IRE genes are possibly driven by iron dyshomeostasis and/or oxidative stress, but illuminate the existence of currently unknown mechanisms with differential overall effects on 5' and 3' IREs.

DJ-1 Deficiency in Hepatocytes Improves Liver Ischemia-Reperfusion Injury by Enhancing Mitophagy.

BACKGROUND & AIMS: DJ-1 is universally expressed in various tissues and organs and is involved in the physiological processes in various liver diseases. However, the role of DJ-1 in liver ischemia-reperfusion (I/R) injury is largely unknown. METHODS: In this study, we first examined the DJ-1 expression changes in the liver tissues of mice and clinical donor after hepatic I/R by both quantitative polymerase chain reaction and Western blotting assays. Then we investigated the role of DJ-1 in I/R injury by using a murine liver I/R model. RESULTS: We demonstrated that DJ-1 down-regulation in both human and mouse liver tissues in response to I/R injury and Dj-1 deficiency in hepatocytes but not in myeloid cells could significantly ameliorate I/R induced liver injury and inflammatory responses. This hepatoprotective effect was dependent on enhanced autophagy in Dj-1 knockout mice, because inhibition of autophagy by 3-methyladenine and chloroquine could reverse the protective effect on hepatic I/R injury in Dj-1 knockout mice. CONCLUSIONS: Dj-1 deficiency in hepatocytes significantly enhanced mitochondrial accumulation and protein stability of PARKIN, which in turn promotes the onset of mitophagy resulting in elevated clearance of damaged mitochondria during I/R injury.

Myeloid DJ-1 deficiency protects acetaminophen-induced acute liver injury through decreasing inflammatory response.

BACKGROUND: DJ-1 (also known as PARK7), a noted protein implicated in modulating ROS production and immune response, has been observed to play critical roles in the pathogenesis of many forms of liver disease through multiple mechanisms. However, its role and specific mechanism in acetaminophen (APAP) -induced liver injury have not been explored. RESULTS: In this present study, by employing an acute liver injury induced by APAP overdose mouse model, we demonstrated that DJ-1 knockout (DJ-1-/-) mice showed reduced liver injury and lower mortality. In accordance with these changes, there were also alleviating inflammatory responses in both the serum and the liver of the DJ-1-/- mice compared to those of the wild-type (WT) mice. Functional experiments showed that APAP metabolism did not affected by DJ-1 deficiency. In addition, to investigate DJ-1 modulates which kind of cell types during APAP-overdose-induced acute liver injury, hepatocyte-specific DJ-1-knockout (Alb-DJ-1-/-) and myeloid-specific DJ-1-knockout (Lysm-DJ-1-/-) mice were generated. Interestingly, hepatic deletion of DJ-1 did not protect APAP-overdose induced hepatotoxicity and inflammation, whereas Lysm-DJ-1-/- mice showed similar protective effects as DJ-1-/- mice which suggest that the protective effects of deletion of DJ-1 was through modulating myeloid cell function. Consistently, there were alleviated pro-inflammatory cells infiltration and reduced reactive oxygen species (ROS) production in the liver of Lysm-DJ-1-/- mice relative to control mice. CONCLUSION: our findings clearly defined that deletion of DJ-1 protects APAP-induced acute liver injury through decreasing inflammatory response, and suggest DJ-1 as a potential therapeutic and/or prophylactic target of APAP-induced acute liver injury.

DJ-1 inhibits microglial activation and protects dopaminergic neurons in vitro and in vivo through interacting with microglial p65.

Parkinson's disease (PD), one of the most common neurodegenerative disorders, is characterized by progressive neurodegeneration of dopaminergic (DA) neurons in the substantia nigra pars compacta (SNpc). DJ-1 acts essential roles in neuronal protection and anti-neuroinflammatory response, and its loss of function is tightly associated with a familial recessive form of PD. However, the molecular mechanism of DJ-1 involved in neuroinflammation is largely unclear. Here, we found that wild-type DJ-1, rather than the pathogenic L166P mutant DJ-1, directly binds to the subunit p65 of nuclear factor-κB (NF-κB) in the cytoplasm, and loss of DJ-1 promotes p65 nuclear translocation by facilitating the dissociation between p65 and NF-κB inhibitor α (IκBα). DJ-1 knockout (DJ-1-/-) mice exhibit more microglial activation compared with wild-type littermate controls, especially in response to lipopolysaccharide (LPS) treatment. In cellular models, knockdown of DJ-1 significantly upregulates the gene expression and increases the release of LPS-treated inflammatory cytokines in primary microglia and BV2 cells. Furthermore, DJ-1 deficiency in microglia significantly enhances the neuronal toxicity in response to LPS stimulus. In addition, pharmacological blockage of NF-κB nuclear translocation by SN-50 prevents microglial activation and alleviates the damage of DA neurons induced by microglial DJ-1 deficiency in vivo and in vitro. Thus, our data illustrate a novel mechanism by which DJ-1 facilitates the interaction between IκBα and p65 by binding to p65 in microglia, and thus repressing microglial activation and exhibiting the protection of DA neurons from neuroinflammation-mediated injury in PD.

Deletion of DJ-1 in rats affects protein abundance and mitochondrial function at the synapse.

DJ-1 is a multifunctional protein affecting different biological and cellular processes. In addition, DJ-1 has roles in regulating mitochondrial function. Loss-of-function mutations in DJ-1 were found to cause an autosomal recessive form of Parkinson's disease. One of the main pathological features of PD is loss of dopamine neurons in the nigrostriatal pathway. DJ-1 knockout (KO) rats exhibit progressive nigral neurodegeneration with about 50% dopaminergic cell loss at 8 months of age. In order to assess the effects of DJ-1 deficiency on neuronal mitochondria prior to neuron loss, we performed proteomic analysis of synaptic mitochondria isolated from the striatum, the location of nigrostriatal pathway nerve terminals, of 3-month-old DJ-1 KO rats. In total, 371 mitochondrial proteins were quantified, and of these 76 were differentially expressed in DJ-1 KO rats. Proteins perturbed by the loss of DJ-1 were involved in several mitochondrial functional pathways, including the tricarboxylic acid cycle and electron transport chain. Thus, synaptic mitochondrial respiration was measured and showed a significant change due to DJ-1 deficiency. The dataset generated here highlights the role of synaptic mitochondria in PD associated with DJ-1. This study improves our understanding of DJ-1 effects in a complex tissue environment and the synaptic mitochondrial changes that accompany its loss.

Uncoupling Protein 2 Increases Blood Pressure in DJ -1 Knockout Mice.

Background The redox-sensitive chaperone DJ -1 and uncoupling protein 2 are protective against mitochondrial oxidative stress. We previously reported that renal-selective depletion and germline deletion of DJ -1 increases blood pressure in mice. This study aimed to determine the mechanisms involved in the oxidative stress-mediated hypertension in DJ -1 -/- mice. Methods and Results There were no differences in sodium excretion, renal renin expression, renal NADPH oxidase activity, and serum creatinine levels between DJ -1 -/- and wild-type mice. Renal expression of nitro-tyrosine, malondialdehyde, and urinary kidney injury marker-1 were increased in DJ -1 -/- mice relative to wild-type littermates. mRNA expression of mitochondrial heat shock protein 60 was also elevated in kidneys from DJ -1 -/- mice, indicating the presence of oxidative stress. Tempol-treated DJ -1 -/- mice presented higher serum nitrite/nitrate levels than vehicle-treated DJ -1 -/- mice, suggesting a role of the NO system in the high blood pressure of this model. Tempol treatment normalized renal kidney injury marker-1 and malondialdehyde expression as well as blood pressure in DJ -1 -/- mice, but had no effect in wild-type mice. The renal Ucp2 mRNA expression was increased in DJ -1 -/- mice versus wild-type and was also normalized by tempol. The renal-selective silencing of Ucp2 led to normalization of blood pressure and serum nitrite/nitrate ratio in DJ -1 -/- mice. Conclusions The deletion of DJ -1 leads to oxidative stress-induced hypertension associated with downregulation of NO function, and overexpression of Ucp2 in the kidney increases blood pressure in DJ -1 -/- mice. To our knowledge, this is the first report providing evidence of the role of uncoupling protein 2 in blood pressure regulation.