DJ-1 Knockout Mice Research Articles

Growth of B16F10 cells is enhanced in DJ-1-deficiency pancreas

Association between cancer risk and Parkinson's disease is still debated. DJ-1, a Parkinson's disease (PD)-related gene, is encoded by PARK-7 gene and its deficiency causes early-onset PD. In our last studies, it was found that the immunosuppressive microenvironment established in DJ-1 knockout (KO) mice can enhance metastasis of melanoma cells to lungs. Therefore, we wanted to further examine whether there were some niche in other organs of DJ-1-deficiency mouse to facilitate cell growth of tumors. We used in vivo tissue-specific models of tumor growth and in vitro cellular model to verify the hypothesis. We also used protein blot assay, cell-adhesion assay and bioinformatic tools to conduct experiments. In the mouse model of subcutaneous injection, there was no difference on tumor growth between WT and DJ-1 KO mice. Moreover, the results of experimental liver metastasis by intrasplenic injection model showed that there was no difference of nodules number in both mice, but a dramatic enhancement of nodule formation and increased mucin4 levels were found in pancreas of DJ-1 KO mice. In cell cultures, we further found that B16F10 cells indeed tended to adhere well to primary DJ-1-deficiency pancreatic epithelial cells, which had higher protein levels of mucin4. Notably, a human database also showed the inverse relationship in human pancreas between DJ-1 and mucin4, and mucin4 down-regulation can reverse the enhanced cellular adhesion in DJ-1 KO pancreatic epithelial cells. These results indicated that DJ-1 KO pancreatic tissue creating an appropriate microenvironment benefited development of the cancer cells.

Altered prefrontal neurochemistry in the DJ-1 knockout mouse model of Parkinson's disease: complementary semi-quantitative analyses with in vivo magnetic resonance spectroscopy and MALDI-MSI.

In vivo proton magnetic resonance spectroscopy (1H-MRS) and matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI-MSI) are two semi-quantitative analytical methods commonly used in neurochemical research. In this study, the two methods were used complementarily, in parallel, to investigate neurochemical perturbations in the medial prefrontal cortex (mPFC) of 9-month-old DJ-1 knockout mice, a well-established transgenic model for Parkinson's diseases. Convergingly, the results obtained with the two methods demonstrated that, compared with the wild-type (WT) mice, the DJ-1 knockout mice had significantly increased glutathione (GSH) level and GSH/glutamate (Glu) ratio in the mPFC, which likely presented an astrocytic compensatory mechanism in response to elevated regional oxidative stress induced by the loss of DJ-1 function. The results from this study also highlighted (1) the need to be cautious when interpreting the in vivo 1H-MRS results obtained from aged transgenic animals, in which the concentration of internal reference, being whether water or total creatine, could no longer be assumed to be the same as that in the age-matched WT animals, and (2) the necessity and importance of complementary analyses with more than one method under such circumstances.

DJ-1 governs airway progenitor cell/eosinophil interactions to promote allergic inflammation

DJ-1 is an antioxidant protein known to regulate mast cell-mediated allergic response, but its role in airway eosinophilic interactions and allergic inflammation is not known. The aim of this study was to investigate the role of DJ-1 in airway eosinophilic inflammation invitro and invivo. Ovalbumin-induced airway allergic inflammation was established in mice. ELISA was adopted to analyze DJ-1 and cytokine levels in mouse bronchoalveolar lavage fluid. Transcriptional profiling of mouse lung tissues was conducted by single-cell RNA-sequencing technology. The role of DJ-1 in the differentiation of airway progenitor cells into goblet cells was examined by organoid cultures, immunofluorescence staining, quantitative PCR, and cell transplantation in normal, DJ-1 knockout (KO), or conditional DJ-1 KO mice. This study observed that DJ-1 was increased in the lung tissues of ovalbumin-sensitized and challenged mice. DJ-1 KO mice exhibited reduced airway eosinophil infiltration and goblet cell differentiation. Mechanistically, we discovered that eosinophil-club cell interactions are reduced in the absence of DJ-1. Organoid cultures indicated that eosinophils impair the proliferative potential of club cells. Intratracheal transplantation of DJ-1-deficient eosinophils suppresses airway goblet cell differentiation. Loss of DJ-1 inhibits the metabolism of arachidonic acid into cysteinyl leukotrienes in eosinophils while these secreted metabolites promote airway goblet cell fate in organoid cultures and invivo. DJ-1-mediated interactions between airway epithelial progenitor cells and immune cells are essential in controlling airway goblet cell metaplasia and eosinophilia. Blockade of the DJ-1 pathway is protective against airway allergic inflammation.

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.

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

Background & AimsDJ-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.MethodsIn 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.ResultsWe 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.ConclusionsDj-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.

DJ-1 (Park7) affects the gut microbiome, metabolites and the development of innate lymphoid cells (ILCs)

The proper communication between gut and brain is pivotal for the maintenance of health and, dysregulation of the gut-brain axis can lead to several clinical disorders. In Parkinson’s disease (PD) 85% of all patients experienced constipation many years before showing any signs of motor phenotypes. For differential diagnosis and preventive treatment, there is an urgent need for the identification of biomarkers indicating early disease stages long before the disease phenotype manifests. DJ-1 is a chaperone protein involved in the protection against PD and genetic mutations in this protein have been shown to cause familial PD. However, how the deficiency of DJ-1 influences the risk of PD remains incompletely understood. In the present study, we provide evidence that DJ-1 is implicated in shaping the gut microbiome including; their metabolite production, inflammation and innate immune cells (ILCs) development. We revealed that deficiency of DJ-1 leads to a significant increase in two specific genera/species, namely Alistipes and Rikenella. In DJ-1 knock-out (DJ-1-/-) mice the production of fecal calprotectin and MCP-1 inflammatory proteins were elevated. Fecal and serum metabolic profile showed that malonate which influences the immune system was significantly more abundant in DJ-1−/− mice. DJ-1 appeared also to be involved in ILCs development. Further, inflammatory genes related to PD were augmented in the midbrain of DJ-1−/− mice. Our data suggest that metabolites and inflammation produced in the gut could be used as biomarkers for PD detection. Perhaps, these metabolites and inflammatory mediators could be involved in triggering inflammation resulting in PD pathology.

Oxidative stress in the retina and retinal pigment epithelium (RPE): Role of aging, and DJ-1

High levels of oxidative radicals generated by daily light exposure and high metabolic rate suggest that the antioxidant machinery of the retina and retinal pigment epithelium (RPE) is crucial for their survival. DJ-1 is a redox-sensitive protein that has been shown to have neuroprotective function in the brain in Parkinson's disease and other neurodegenerative diseases. Here, we analyzed the role of DJ-1 in the retina during oxidative stress and aging. We induced low-level oxidative stress in young (3-month-old) and old (15-month-old) C57BL/6J (WT) and DJ-1 knockout (KO) mice and evaluated effects in the RPE and retina. Absence of DJ-1 resulted in increased retinal dysfunction in response to low levels of oxidative stress. Our findings suggest that loss of DJ-1 affects the RPE antioxidant machinery, rendering it unable to combat and neutralize low-level oxidative stress, irrespective of age. Moreover, they draw a parallel to the retinal degeneration observed in AMD, where the occurrence of genetic variants may leave the retina and RPE unable to fight sustained, low-levels of oxidative stress.

Real-time and in-situ intracellular ATP assay with polyimidazolium brush-modified nanopipette

The level and dynamics of adenosine 5-triphosphate (ATP) in single living cells are closely related to many kinds of important physiological and pathological processes. Herein, we report a nanosensor based on polyimidazolium brush (PimB)-modified nanopipette for intracellular ATP assay, which shows good selectivity, high spatiotemporal resolution and excellent stability. Both the specific supramolecular interaction between polyimidazolium and ATP, and the rationally tunable property of the ion transport at a confined nanopipette enable the selective assay of ATP even in complex intracellular environment. Moreover, the tiny tip ( ca. 300 nm) and the low polarized current (e.g., 1 nA) essentially make the as-prepared nanosensor safe to the living cells. The nanosensor is demonstrated to be useful for in-situ monitoring the basal ATP levels of chromaffin cells from wild-type mice and DJ-1 knockout mice, and for real-time monitoring the metabolism process of intracellular ATP.

DJ-1 regulates the integrity and function of ER-mitochondria association through interaction with IP3R3-Grp75-VDAC1

Loss-of-function mutations in DJ-1 are associated with autosomal recessive early onset Parkinson's disease (PD), yet the underlying pathogenic mechanism remains elusive. Here we demonstrate that DJ-1 localized to the mitochondria-associated membrane (MAM) both in vitro and in vivo. In fact, DJ-1 physically interacts with and is an essential component of the IP3R3-Grp75-VDAC1 complexes at MAM. Loss of DJ-1 disrupted the IP3R3-Grp75-VDAC1 complex and led to reduced endoplasmic reticulum (ER)-mitochondria association and disturbed function of MAM and mitochondria in vitro. These deficits could be rescued by wild-type DJ-1 but not by the familial PD-associated L166P mutant which had demonstrated reduced interaction with IP3R3-Grp75. Furthermore, DJ-1 ablation disturbed calcium efflux-induced IP3R3 degradation after carbachol treatment and caused IP3R3 accumulation at the MAM in vitro. Importantly, similar deficits in IP3R3-Grp75-VDAC1 complexes and MAM were found in the brain of DJ-1 knockout mice in vivo. The DJ-1 level was reduced in the substantia nigra of sporadic PD patients, which was associated with reduced IP3R3-DJ-1 interaction and ER-mitochondria association. Together, these findings offer insights into the cellular mechanism in the involvement of DJ-1 in the regulation of the integrity and calcium cross-talk between ER and mitochondria and suggests that impaired ER-mitochondria association could contribute to the pathogenesis of PD.

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.

The relationship between DJ-1 and S100A8 in human primary alveolar type II cells in emphysema.

Pulmonary emphysema is characterized by alveolar type II (ATII) cell death, destruction of alveolar wall septa, and irreversible airflow limitation. Cigarette smoke induces oxidative stress and is the main risk factor for this disease development. ATII cells isolated from nonsmokers, smokers, and patients with emphysema were used for this study. ATII cell apoptosis in individuals with this disease was detected. DJ-1 and S100A8 have cytoprotective functions against oxidative stress-induced cell injury. Reduced DJ-1 and S100A8 interaction was found in ATII cells in patients with emphysema. The molecular function of S100A8 was determined by an analysis of the oxidation status of its cysteine residues using chemoselective probes. Decreased S100A8 sulfination was observed in emphysema patients. In addition, its lower levels correlated with higher cell apoptosis induced by cigarette smoke extract in vitro. Cysteine at position 106 within DJ-1 is a central redox-sensitive residue. DJ-1 C106A mutant construct abolished the cytoprotective activity of DJ-1 against cell injury induced by cigarette smoke extract. Furthermore, a molecular and complementary relationship between DJ-1 and S100A8 was detected using gain- and loss-of-function studies. DJ-1 knockdown sensitized cells to apoptosis induced by cigarette smoke extract, and S100A8 overexpression provided cytoprotection in the absence of DJ-1. DJ-1 knockout mice were more susceptible to ATII cell apoptosis induced by cigarette smoke compared with wild-type mice. Our results indicate that the impairment of DJ-1 and S100A8 function may contribute to cigarette smoke-induced ATII cell injury and emphysema pathogenesis.

DJ-1 regulates tyrosine hydroxylase expression through CaMKKβ/CaMKIV/CREB1 pathway in vitro and in vivo.

Lack of dopamine production and neurodegeneration of dopaminergic neurons in the substantia nigra are considered as the major characteristics of Parkinson's disease, a prevalent movement disorder worldwide. DJ-1 mutation leading to loss of its protein functions is a genetic factor of PD. In this study, our results illustrated that DJ-1 can directly interact with Ca2+ /calmodulin-dependent protein kinase kinase β (CaMKKβ) and modifies the cAMP-responsive element binding protein 1 (CREB1) activity, thus regulates tyrosine hydroxylase (TH) expression. In Dj-1 knockout mouse substantia nigra, the levels of TH and the phosphorylation of CREB1 Ser133 are significantly decreased. Moreover, Dj-1 deficiency suppresses the phosphorylation of CaMKIV (Thr196/200) and CREB1 (Ser133), subsequently inhibits TH expression in vitro. Furthermore, Knockdown of Creb1 abolishes the effects of DJ-1 on TH regulation. Our data reveal a novel pathway in which DJ-1 regulates CaMKKβ/CaMKIV/CREB1 activities to facilitate TH expression.

Structure and function of DJ-1 and its role in Parkinson's disease

Parkinson's disease (PD) is a neurodegenerative movement disorder mainly due to degeneration of dopaminergic neurons in the substantia nigra. Most PD cases are sporadic and only 5%-10% of patients carry mutations with inheritance. Among them, the mutation of DJ-1 is related to the autosomal recessive early-onset parkinsonism. DJ-1, the Parkinson's disease-related protein, plays important roles in different physiopathological processes, including oxidative stress, cell translocation and regulation of transcription and translation. DJ-1 is known to be widely expressed in different areas of brain, including hippocampus, amygdala, substantia nigra and cortical areas. Several researchers have tried to demonstrate the clinical and neuroimaging features of DJ-1 related parkinsonism. The DJ-1 knockout mouse model was established to further explore the mechanisms of different functions. Moreover, the search for different forms of DJ-1 as potential biomarkers of PD also provides guidance for its accurate diagnosis and treatment in the future.

Impact of Dopamine Oxidation on Dopaminergic Neurodegeneration.

Parkinson's disease (PD) is the second most common neurodegenerative disease. The characteristic feature of PD is the progressive degeneration of the dopaminergic (DAergic) neurons in the substantia nigra (SN). DAergic neurons in the SN accumulate black and insoluble membrane structures known as neuromelanin during aging. The oxidation of dopamine (DA) to form neuromelanin generates many o-quinones, including DA o-quinones, aminochrome, and 5,6-indolequinone. The focus of this review is to discuss the role of DA oxidation in association with PD. The oxidation of DA produces oxidative products, inducing mitochondrial dysfunction, impaired protein degradation, α-synuclein aggregation into neurotoxic oligomers, and oxidative stress, in vitro. Recent studies have demonstrated that the DA content is critical for both DJ-1 knockout and A53T α-synuclein transgenic mice to develop PD pathological features, providing evidence for DA action in PD pathogenesis in vivo. The effects of L-DOPA, as the most effective anti-PD drug, are also briefly discussed.

309 - Analysis of oxidative stress-mediated degeneration in retina and RPE using sodium iodate (NaIO3) Model

In the eye, the retina and RPE (retinal pigmented epithelium) are exposed to high levels of oxidative radicals generated by light exposure and high metabolic rate. Degeneration of these cells due to cumulative oxidative damage plays an important role in diseases like AMD (Age-related Macular Degeneration) and subsequent blindness. The underlying mechanisms of AMD remain unclear, and therefore extensive studies are needed to help combat the disease. We use sodium iodate, an oxidizing agent that preferentially degenerate RPE, to induce oxidative stress in young and old mice. DJ-1, Parkinson’s Disease (PD)-associated gene protects neurons from oxidative damages. High levels of DJ-1 were observed in RPE and photoreceptors of adult mice retina. DJ-1 loss results in age-related mild structural and physiological changes in retinas of DJ-1 knockout mice. Control (C57BL/6) and DJ-1 knockout 3- and 15- month-old mice were injected with 10mg/kg sodium iodate to gain insight into oxidative stress mechanisms in RPE and retina.Histological sections revealed that oxidative stress in DJ-1 knockout resulted in increased RPE and photoreceptor cells degeneration compared to controls. Gene expression analysis for antioxidant genes was carried out. The transcript levels of these genes were significantly upregulated in RPE of DJ-1 knockout compared to control but downregulated in the retina in 3-month-old mice. In 15-month-old mice, transcript levels of these genes were significantly downregulated in RPE of DJ-1 knockout compared to control but remained unchanged in the retina. Injection of mice with 10mg/Kg NaIO3 differentially regulated the expression of these transcripts in the RPE and retinas. Overall, our data suggest that loss of DJ-1 renders RPE and retina more susceptible to oxidative damage.

Ablation of DJ-1 impairs brown fat function in diet-induced obese mice

This study was conducted to investigate the effects of DJ-1 deficiency on brown adipose tissue (BAT) function in mice. DJ-1 knockout (KO) mouse models and wild-type littermates placed on a normal diet or high-fat diet were utilized to demonstrate the direct consequences of DJ-1 deletion on BAT characteristics, thermogenic ability, lipid metabolism, and microenvironment regulation. Global DJ-1 KO mice had defective brown adipose tissue activity culminating in a profound whitening of BAT. Despite aberrations in inactive BAT associated with greater lipid accretion, decreased sympathetic activity, mitochondrial dysfunction, reduced vascularity, and autophagy activation, we found that the body weight and energy balance were unaffected in male mice depleted of DJ-1. Taken together, the results of this study suggest that male DJ-1 KO mice exhibit defects in BAT activity but do not gain more weight, revealing that BAT activity is not necessarily required for predisposing DJ-1 KO mice to obesity. Therefore, therapeutic targeting of DJ-1 in BAT could provide novel insights into the treatment of obesity.

Loss of DJ-1 promotes browning of white adipose tissue in diet-induced obese mice

The seminal discovery of browning of white adipose tissue (WAT) holds great promise for the treatment of obesity and metabolic syndrome. DJ-1 is evolutionarily conserved across species, and mutations in DJ-1 have been identified in Parkinson's disease. Higher levels of DJ-1 are associated with obesity, but the underlying mechanism is less understood. Here, we report the previously unappreciated role of DJ-1 in white adipocyte biology in mature models of obesity. We used DJ-1 knockout (KO) mouse models and wild-type littermates maintained on a normal diet or high-fat diet as well as in vitro cell models to show the direct effects of DJ-1 depletion on adipocyte phenotype, thermogenic capacity, fat metabolism, and microenvironment profile. Global DJ-1 KO mice show increased sympathetic input to WAT and β3-adrenergic receptor intracellular signaling, leading to a previously unrecognized compensatory mechanism through browning of WAT with associated characteristics, including high mitochondrial contents, reduced lipid accumulation, adequate vascularization and attenuated autophagy. DJ-1 KO mice had normal body weight, energy balance, and adiposity, which were associated with protective effects on healthy WAT expansion by hyperplasia. Our findings revealed that browning of inguinal WAT occurred in DJ-1 KO mice that do not show increased predisposition to obesity and suggest that such potential mechanism may overcome the adverse metabolic consequences of obesity independent of an effect on body weight. Here, we provide the first direct evidence that targeting DJ-1 in adipocyte metabolic health may offer a unique therapeutic strategy for the treatment of obesity.

Parkinson's disease-related DJ-1 modulates the expression of uncoupling protein 4 against oxidative stress.

Loss of function mutations of DJ-1 (PARK7) have been linked to the pathogenesis of Parkinson's disease. Antioxidative stress is one of the multi-protective functions of DJ-1, and oxidation of cysteine 106 has been proposed to regulate the protective activity of DJ-1. Uncoupling protein 4 (UCP4) is located in the inner membrane of mitochondria and functions to protect against oxidative stress. In this study, we used neuronal (SH-SY5Y) cells and DJ-1 knockout mice to elucidate whether DJ-1 regulated oxidative stress via modulating the expression of UCP4, and the underlying mechanism. The downstream products of oxidative stress, mitochondrial membrane potential (ΔΨm) and cell viability were also investigated. We found that UCP4 was up-regulated upon 1-methyl-4-phenylpyridinium (MPP+ ) stimulation in SH-SY5Y cells, which was enhanced by wild type DJ-1 and alleviated by DJ-1 knockdown. Expression of UCP4 in DJ-1 knockout mice was lower compared with wild-type mice. In addition, up-regulation of UCP4 was alleviated by inhibition of oxidized DJ-1, and enhanced by increase in oxidized DJ-1 under conditions of oxidative stress using western blot analysis. Moreover, over-expression of UCP4 in DJ-1 knockdown cells partially reversed the decrease in cell viability, ΔΨm, as well as the increase in products of oxidative stress upon MPP+ stimulation. Furthermore analysis showed that DJ-1 regulated transcriptional activity of UCP4 partially via Nuclear factor-kappa B (NF-κB) pathway in the presence of MPP+ . Together, our results suggested DJ-1 might regulate the expression of UCP4 by oxidation of DJ-1 and partially via NF-κB pathway in its protective response to oxidative stress.

DJ-1 is involved in epigenetic control of sphingosine-1-phosphate receptor expression in vascular neointima formation.

DJ-1 and sphingosine-1-phosphate (S1P) receptors (S1PRs) are implicated in the control of physiology and pathophysiology of cardiovascular systems such as blood pressure, atherosclerosis, and restenosis. Here, we investigated whether DJ-1 with antioxidant function participates in the regulation of S1PR1 and S1PR2 expression in vascular smooth muscle cells (VSMCs) and whether this response is related to vascular neointima formation. In vitro studies used cellular migration assay, western blot, reverse transcriptase and real-time PCR analysis, and immunocytochemistry. In vivo studies were performed using the carotid artery ligation model together with immunohistochemistry in DJ-1 knockout (DJKO) and corresponding wild-type (DJWT) mice. S1P stimulated migration of VSMCs from DJKO and DJWT mice. VSMC migration was suppressed by S1PR1 inhibitor but was elevated by S1PR2 inhibitor. Compared with DJWT mice, S1PR1 expression was higher in VSMCs and neointimal plaque from DJKO mice, but S1PR2 expression was lower. Overexpression of DJ-1 in DJKO VSMCs reduced S1PR1 expression and elevated S1PR2 expression. Compared with DJWT mice, histone deacetylase-1 recruitment and histone H3 acetylation at the S1PR1 promoter region were lower and higher, respectively, but this pattern was reversed at the S1PR2 promoter region in DJKO VSMCs. S1PR expressions and epigenetic changes at S1PR promoter regions in DJWT VSMCs treated with H2O2 showed similar patterns to those in DJKO VSMCs. Our findings suggest that DJ-1 may be involved in the regulation of S1PR1 and S1PR2 expression via H2O2-mediated histone modification in VSMCs. Consequently, this modification may affect S1P-induced VSMC migration and be related to vascular neointima formation.