Differential effect of DJ-1/PARK7 on development of natural and induced regulatory T cells

DJ-1: A Potential Biomarker Related to Prognosis, Chemoresistance, and Expression of Microenvironmental Chemokine in HR-Positive Breast Cancer

DJ-1 is significantly elevated in various malignancies. However, the clinical significance of DJ-1 in hormone receptor (HR)-positive (HR+) breast cancer remains unclear. We evaluated DJ-1 expression in different databases and validated in vitro assay by RT-PCR and western blot among HR+ breast cancer. The correlations between DJ-1 level and tumor-immune were calculated. Mutational landscape, enriched signaling pathways, and drug sensitivity analyses were also assessed between DJ-1 high and low-expression groups. DJ-1 was upregulated in HR+ breast cancer, and high DJ-1 expression was significantly linked with poor prognosis. DJ-1 was correlated with the expression and function of different immune cells. The low DJ-1 group showed sensitivity to paclitaxel and docetaxel, while the high-expression group showed sensitivity to doxorubicin. CTLA4 and PD-L1 were more sensitive in high-DJ-1 group. It is involved in a range of pathways and might behave as a novel biomarker of prognostic value for the immune environment and drug sensitivity in HR+ breast cancer.

Relevance of tissue-resident memory CD8 T cells in the onset of Parkinson's disease and examination of its possible etiologies: infectious or autoimmune?

Tissue-resident memory CD8 T cells are responsible for local immune surveillance in different tissues, including the brain. They constitute the first line of defense against pathogens and cancer cells and play a role in autoimmunity. A recently published study demonstrated that CD8 T cells with markers of residency containing distinct granzymes and interferon-γ infiltrate the parenchyma of the substantia nigra and contact dopaminergic neurons in an early premotor stage of Parkinson's disease. This infiltration precedes α-synuclein aggregation and neuronal loss in the substantia nigra, suggesting a relevant role for CD8 T cells in the onset of the disease. To date, the nature of the antigen that initiates the adaptive immune response remains unknown. This review will discuss the role of tissue-resident memory CD8 T cells in brain immune homeostasis and in the onset of Parkinson's disease and other neurological diseases. We also discuss how aging and genetic factors can affect the CD8 T cell immune response and how animal models can be misleading when studying human-related immune response. Finally, we speculate about a possible infectious or autoimmune origin of Parkinson's disease.

Inflammation and immune dysfunction in Parkinson disease

Parkinson disease (PD) is a progressive neurodegenerative disease that affects peripheral organs as well as the central nervous system and involves a fundamental role of neuroinflammation in its pathophysiology. Neurohistological and neuroimaging studies support the presence of ongoing and end-stage neuroinflammatory processes in PD. Moreover, numerous studies of peripheral blood and cerebrospinal fluid from patients with PD suggest alterations in markers of inflammation and immune cell populations that could initiate or exacerbate neuroinflammation and perpetuate the neurodegenerative process. A number of disease genes and risk factors have been identified as modulators of immune function in PD and evidence is mounting for a role of viral or bacterial exposure, pesticides and alterations in gut microbiota in disease pathogenesis. This has led to the hypothesis that complex gene-by-environment interactions combine with an ageing immune system to create the 'perfect storm' that enables the development and progression of PD. We discuss the evidence for this hypothesis and opportunities to harness the emerging immunological knowledge from patients with PD to create better preclinical models with the long-term goal of enabling earlier identification of at-risk individuals to prevent, delay and more effectively treat the disease.

Immunogenetic Determinants of Parkinson’s Disease Etiology

Parkinson’s disease (PD) is increasingly recognised as a systemic disorder in which inflammation might play a causative role rather than being a consequence or an epiphenomenon of the neurodegenerative process. Although growing genetic evidence links the central and peripheral immune system with both monogenic and sporadic PD, our understanding on how the immune system contributes to PD pathogenesis remains a daunting challenge. In this review, we discuss recent literature aimed at exploring the role of known genes and susceptibility loci to PD pathogenesis through immune system related mechanisms. Furthermore, we outline shared genetic etiologies and interrelations between PD and autoimmune diseases and underlining challenges and limitations faced in the translation of relevant allelic and regulatory risk loci to immune-pathological mechanisms. Lastly, with the field of immunogenetics expanding rapidly, we place these insights into a future context highlighting the prospect of immune modulation as a promising disease-modifying strategy.

Oxidative stress and synaptic dysfunction in rodent models of Parkinson's disease

Parkinson's disease (PD) is a multifactorial disorder involving a complex interplay between a variety of genetic and environmental factors. In this scenario, mitochondrial impairment and oxidative stress are widely accepted as crucial neuropathogenic mechanisms, as also evidenced by the identification of PD-associated genes that are directly involved in mitochondrial function. The concept of mitochondrial dysfunction is closely linked to that of synaptic dysfunction. Indeed, compelling evidence supports the role of mitochondria in synaptic transmission and plasticity, although many aspects have not yet been fully elucidated. Here, we will provide a brief overview of the most relevant evidence obtained in different neurotoxin-based and genetic rodent models of PD, focusing on mitochondrial impairment and synaptopathy, an early central event preceding overt nigrostriatal neurodegeneration. The identification of early deficits occurring in PD pathogenesis is crucial in view of the development of potential disease-modifying therapeutic strategies.

DJ-1 controls T cell differentiation and osteoclastogenesis in rheumatoid arthritis

Herein, we investigated the effect of DJ-1 on helper T cell differentiation, fibroblast-like synoviocyte (FLS) activation, and osteoclastogenesis in rheumatoid arthritis (RA). Serum and synovial fluid (SF) of RA and osteoarthritis (OA) patients were collected, and DJ-1 and H₂O₂ levels were investigated. CD4⁺ cells from peripheral blood mononuclear cells (PBMCs) were cultured under type 17 helper T cell (Th17) polarization conditions, and CD4⁺ T cell differentiation, pro-inflammatory cytokine levels, and soluble receptor activator of nuclear factor kappa-Β ligand (RANKL) were assessed. RA-FLSs were stimulated with 50 μM H₂O₂, and DJ-1 (10, 50, 100 ng/mL) to evaluate MMP-9, VEGF, TNF-α, and sRANKL production, while RANKL⁺ FLSs were assessed using flow cytometry. Monocytes were cultured with RANKL or IL-17A with or without DJ-1 and H₂O₂-pretreated RA-FLS, and tartrate-resistant acid phosphatase (TRAP) staining and RT-qPCR of osteoclast-related genes were performed. The levels of DJ-1 and H₂O₂ in serum and SF of RA patients were higher than those of OA patients. Under Th17-polarizing conditions, CD4⁺RANKL⁺ and CD4⁺CCR4⁺CCR6⁺CXCR3^- T cells decreased, whereas CD4⁺CD25^highFoxp3⁺ T cell increased after DJ-1 administration. Additionally, IL-17A, TNF-α, and sRANKL levels decreased in DJ-1-treated groups. DJ-1 lowered MMP-9, VEGF, TNF-α, and sRANKL levels, and RANKL⁺ FLS in ROS-stimulated RA-FLS. Both RANKL and IL-17A stimulated osteoclast differentiation, DJ-1 decreased TRAP⁺ cell count, and the expression levels of TRAP, ATP6v0d2, NFATc1, and CTSK. These findings were also observed in in vitro osteoclastogenesis with DJ-1 pretreated RA-FLS. As DJ-1 regulates Th17/Treg imbalance, pro-inflammatory cytokine production, RA-FLS activation, and osteoclastogenesis, it holds potential for RA therapy.

PARK7/DJ-1 as a Therapeutic Target in Gut-Brain Axis Diseases

It is increasingly known that Parkinson's (PD) and Alzheimer's (AD) diseases occur more frequently in patients with inflammatory gastrointestinal diseases including inflammatory bowel (IBD) or celiac disease, indicating a pathological link between them. Although epidemiological observations suggest the existence of the gut-brain axis (GBA) involving systemic inflammatory and neural pathways, little is known about the exact molecular mechanisms. Parkinson's disease 7 (PARK7/DJ-1) is a multifunctional protein whose protective role has been widely demonstrated in neurodegenerative diseases, including PD, AD, or ischemic stroke. Recent studies also revealed the importance of PARK7/DJ-1 in the maintenance of the gut microbiome and also in the regulation of intestinal inflammation. All these findings suggest that PARK7/DJ-1 may be a link and also a potential therapeutic target in gut and brain diseases. In this review, therefore, we discuss our current knowledge about PARK7/DJ-1 in the context of GBA diseases.

PARK7/DJ-1 promotes pyruvate dehydrogenase activity and maintains Treg homeostasis during ageing

Pyruvate dehydrogenase (PDH) is the gatekeeper enzyme of the tricarboxylic acid (TCA) cycle. Here we show that the deglycase DJ-1 (encoded by PARK7, a key familial Parkinson's disease gene) is a pacemaker regulating PDH activity in CD4⁺ regulatory T cells (T_reg cells). DJ-1 binds to PDHE1-β (PDHB), inhibiting phosphorylation of PDHE1-α (PDHA), thus promoting PDH activity and oxidative phosphorylation (OXPHOS). Park7 (Dj-1) deletion impairs T_reg survival starting in young mice and reduces T_reg homeostatic proliferation and cellularity only in aged mice. This leads to increased severity in aged mice during the remission of experimental autoimmune encephalomyelitis (EAE). Dj-1 deletion also compromises differentiation of inducible T_reg cells especially in aged mice, and the impairment occurs via regulation of PDHB. These findings provide unforeseen insight into the complicated regulatory machinery of the PDH complex. As T_reg homeostasis is dysregulated in many complex diseases, the DJ-1-PDHB axis represents a potential target to maintain or re-establish T_reg homeostasis.

Immune Response Modifications in the Genetic Forms of Parkinson's Disease: What Do We Know?

Parkinson's disease (PD) is a common neurodegenerative disease characterized by loss of dopaminergic neurons in the pars compacta of the midbrain substantia nigra. PD pathophysiology is complex, multifactorial, and not fully understood yet. Nonetheless, recent data show that immune system hyperactivation with concomitant production of pro-inflammatory cytokines, both in the central nervous system (CNS) and the periphery, is a signature of idiopathic PD. About 5% of PD patients present an early onset with a determined genetic cause, with either autosomal dominant or recessive inheritance. The involvement of immunity in the genetic forms of PD has been a matter of interest in several recent studies. In this review, we will summarize the main findings of this new and promising field of research.

An immunodominant NP105-113-B*07:02 cytotoxic T cell response controls viral replication and is associated with less severe COVID-19 disease

NP105-113-B*07:02-specific CD8+ T cell responses are considered among the most dominant in SARS-CoV-2-infected individuals. We found strong association of this response with mild disease. Analysis of NP105-113-B*07:02-specific T cell clones and single-cell sequencing were performed concurrently, with functional avidity and antiviral efficacy assessed using an in vitro SARS-CoV-2 infection system, and were correlated with T cell receptor usage, transcriptome signature and disease severity (acute n = 77, convalescent n = 52). We demonstrated a beneficial association of NP105-113-B*07:02-specific T cells in COVID-19 disease progression, linked with expansion of T cell precursors, high functional avidity and antiviral effector function. Broad immune memory pools were narrowed postinfection but NP105-113-B*07:02-specific T cells were maintained 6 months after infection with preserved antiviral efficacy to the SARS-CoV-2 Victoria strain, as well as Alpha, Beta, Gamma and Delta variants. Our data show that NP105-113-B*07:02-specific T cell responses associate with mild disease and high antiviral efficacy, pointing to inclusion for future vaccine design.

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.

Cytoprotective Mechanisms of DJ-1: Implications in Cardiac Pathophysiology

DJ-1 was originally identified as an oncogene product while mutations of the gene encoding DJ-1/PARK7 were later associated with a recessive form of Parkinson's disease. Its ubiquitous expression and diversity of function suggest that DJ-1 is also involved in mechanisms outside the central nervous system. In the last decade, the contribution of DJ-1 to the protection from ischemia-reperfusion injury has been recognized and its involvement in the pathophysiology of cardiovascular disease is attracting increasing attention. This review describes the current and gaps in our knowledge of DJ-1, focusing on its role in regulating cardiovascular function. In parallel, we present original data showing an association between increased DJ-1 expression and antiapoptotic and anti-inflammatory markers following cardiac and vascular surgical procedures. Future studies should address DJ-1's role as a plausible novel therapeutic target for cardiovascular disease.

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.

PARK7 Diminishes Oxidative Stress-Induced Mucosal Damage in Celiac Disease

Coeliac disease (CD) is a chronic, immune-mediated small intestinal enteropathy, accompanied with gluten-triggered oxidative damage of duodenal mucosa. Previously, our research group reported an increased mucosal level of the antioxidant protein Parkinson's disease 7 (PARK7) in children with CD. In the present study, we investigated the role of increased PARK7 level on the epithelial cell and mucosal integrity of the small intestine. The presence of PARK7 was investigated using immunofluorescent staining on duodenal mucosa of children with CD and on FHs74Int duodenal epithelial cells. To investigate the role of oxidative stress, FHs74Int cells were treated with H₂O₂ in the absence or presence of Comp23, a PARK7-binding compound. Intracellular accumulation of reactive oxygen species (ROS) was determined by DCFDA-based assay. Cell viability was measured by MTT, LDH, and Annexin V apoptosis assays. Disruption of cytoskeleton and cell adhesion was investigated by immunofluorescence staining and by real-time RT PCR. Effect of PARK7 on mucosal permeability was investigated ex vivo using intestinal sacs derived from control and Comp-23-pretreated mice. Comp23 treatment reduced the H₂O₂-induced intracellular accumulation of ROS, thus preserving the integrity of the cytoskeleton and also the viability of the FHs74Int cells. Accordingly, Comp23 treatment increased the expression of antioxidants (NRF2, TRX1, GCLC, HMOX1, NQO1), cell-cycle regulators (TP53, CDKN1A, PCNA, BCL2, BAX), and cell adhesion molecules (ZO1, CDH1, VCL, ITGB5) of H₂O₂-treated cells. Pretreatment with Comp23 considerably decreased the small intestinal permeability. In this study, we demonstrate that PARK7-binding Comp23 reduces the oxidative damage of duodenal epithelial cells, via increased expression of NRF2- and P53-regulated genes. Our results suggest that PARK7 plays a significant role in the maintenance of mucosal integrity in CD.

Epigenetic regulation of apoptosis via the PARK7 interactome in peripheral blood mononuclear cells donated by tuberculosis patients vs. healthy controls and the response to treatment: A systems biology approach

AIMS

The aims of our study were to determine for the first time differentially expressed genes (DEGs) and enriched molecular pathways involving the PARK7 interactome in PBMCs donated from tuberculosis patients.

METHODS

Data on a previously reconstructed PARK7 interactome (Vavougios et al., 2017) from datasets GDS4966 (Case-Control) and GDS4781 (Treatment Series) were retrieved from the Gene Expression Omnibus (GEO) repository. Gene Enrichment analysis was performed via the STRING algorithm and the GeneTrail2 software.

RESULTS

17 and 22 PARK7 interactores were determined as DEGs in the active TB vs HD and Treatment Series subset analyses, correspondingly, associated with significantly enriched pathways (FDR <0.05) involving p53 and PTEN mediated, stress responsive apoptosis regulation pathways. The treatment subset was characterized by the emergence of an additional layer of transcriptional regulation mediated by polycomb proteins among others, as well as TLR-mediated and cytokine survival signaling. Finally, the enrichment of a Parkinson's disease signature including PARK7 interactors was determined by its differential regulation both in the exploratory analyses (FDR = 0.024), as well as the confirmatory analyses (FDR = 1.81e^-243).

CONCLUSIONS

Our in silico analysis revealed for the first time the role of PARK7's interactome in regulating the epigenetics of the PBMC lifecycle and Mtb symbiosis.

Role of DJ-1 in Immune and Inflammatory Diseases

The DJ-1 protein, known as an oxidative stress sensor, participates in the onset of oxidative stress-related diseases such as cancer, neurodegenerative disorders, type 2 diabetes, and male infertility. Although DJ-1 has been extensively studied for more than two decades, evidence has only recently emerged that it plays a key role in immune and inflammatory disorders. The immune regulatory function of DJ-1 is achieved by modulating the activation of several immune cells including macrophages, mast cells, and T cells via reactive oxygen species (ROS)-dependent and/or ROS-independent mechanisms. This review describes the current knowledge on DJ-1, focusing on its immune and inflammatory regulatory roles, and highlights the significance of DJ-1 as a novel therapeutic target for immune and inflammatory diseases.

DJ-1/PARK7 inhibits high glucose-induced oxidative stress to prevent retinal pericyte apoptosis via the PI3K/AKT/mTOR signaling pathway

Reactive oxygen species (ROS) act through multiple pathways to induce apoptosis of retinal capillary pericytes, which is an early marker and the primary cause of the progression of diabetic retinopathy. However, the specific molecular mechanisms behind ROS-induced retinal capillary pericyte loss in diabetic retinopathy remains elusive. In this study, we investigated the molecular regulation and effects of DJ-1/PARK7 on oxidative stress and injury of rat retinal pericytes (RRPs). To perform the research, RRPs were isolated from rat retina and cultured in medium with for 2 days: control group (5.6 mM glucose), high glucose group (30 mM glucose), hypertonic group (5.6 mM glucose + 24.4 mM mannitol). We found decreased expression of DJ-1 and increased apoptosis of RRPs in high glucose group. To further study the role of DJ-1, four groups were divided as follows: normal control group (5.6 mM glucose), high glucose (30 mM glucose), empty vector control group (pcDNA3.1,30 mM glucose), DJ-1 overexpression group (pcDNA3.1-myc-DJ-1,30 mM glucose). DJ-1, P53, p-P53, cleaved caspase-3, manganese superoxide dismutase (MnSOD), catalase (CAT) and PI3K/Akt/mTOR signaling pathway in each group was detected by Western Blot. RRPs apoptosis was detected by Terminal-deoxynucleoitidyl Transferase mediated Nick End Labeling (TUNEL) and 4'6- diamidino-2-phenylindole (DAPI). Mitochondrial function was detected by jc-1 and fluorescent probes DCFH-DA was used to determine reactive oxygen species (ROS). We found that high glucose (30 mM) lasting two days can induce significant apoptosis of RRPs, increase ROS production and expressions of p-p53 and active caspase-3, impair mitochondrial function, decrease the activities of MnSOD and CAT, and decrease expression of DJ-1, p-AKT and p-mTOR. In contrast, DJ-1/PARK7 overexpression significantly increases expression of DJ-1, p-AKT and p-mTOR, increases expression and activities of MnSOD and CAT, improves mitochondrial function, decreases expression of apoptotic gene protein p-p53 and active caspase-3, reduces ROS production and reduces the apoptotic rate of RRPs induced by high glucose. These results suggest that DJ-1 may play a role in protecting RRPs from high glucose induced-oxidative injury. DJ-1 might improve mitochondrial function, inhibit ROS production and enhance antioxidant capacity to reduce apoptosis of retinal pericytes through the PI3K/AKT/mTOR signaling pathway which may be related to early pathogenesis of diabetic retinopathy.

The Challenge of the Pathogenesis of Parkinson's Disease: Is Autoimmunity the Culprit?

The role of autoimmunity in Parkinson's disease (PD), as one of the most popular research subjects, has been intensively investigated in recent years. Although the ultimate cause of PD is unknown, one major area of interest remains identifying new therapeutic targets and options for patients suffering from PD. Herein, we present a comprehensive review of the impacts of autoimmunity in neurodegenerative diseases, especially PD, and we have composed a logical argument to substantiate that autoimmunity is actively involved in the pathogenesis of PD through several proteins, including α-synuclein, DJ-1, PINK1, and Parkin, as well as immune cells, such as dendritic cells, microglia, T cells, and B cells. Furthermore, a detailed analysis of the relevance of autoimmunity to the clinical symptoms of PD provides strong evidence for the close correlation of autoimmunity with PD. In addition, the previously identified relationships between other autoimmune diseases and PD help us to better understand the disease pattern, laying the foundation for new therapeutic solutions to PD. In summary, this review aims to integrate and present currently available data to clarify the pathogenesis of PD and discuss some controversial but innovative research perspectives on the involvement of autoimmunity in PD, as well as possible novel diagnostic methods and treatments based on autoimmunity targets.

Increased chemical acetylation of peptides and proteins in rats after daily ingestion of diacetyl analyzed by Nano-LC-MS/MS

Background

Acetylation alters several protein properties including molecular weight, stability, enzymatic activity, protein-protein interactions, and other biological functions. Our previous findings demonstrating that diacetyl/peroxynitrite can acetylate L-lysine, L-histidine, and albumin in vitro led us to investigate whether diacetyl-treated rats suffer protein acetylation as well.

Methods

Wistar rats were administered diacetyl daily for four weeks, after which they were sacrificed, and their lung proteins were extracted to be analysed by Nano-LC-MS/MS (Q-TOF). A C18 reversed-phase column and gradient elution with formic acid/acetonitrile solutions from 2 to 50% over 150 min were used to separate the proteins. Protein detection was performed using a microTOF-Q II (QTOF) equipped with captive source and an electrospray-ionization source. The data from mass spectrometry were processed using a Compass 1.7 and analyzed using Protein Scape, software that uses Mascot algorithms to perform protein searches.

Results

A set of 3,162 acetylated peptides derived from 351 acetylated proteins in the diacetyl-treated group was identified. Among them, 23 targeted proteins were significantly more acetylated in the diacetyl-treated group than in the PBS control. Protein acetylation of the group treated with 540 mg/kg/day of diacetyl was corroborated by Western blotting analysis.

Conclusions

These data support our hypothesis that diacetyl exposure in animals may lead to the generation of acetyl radicals, compounds that attach to proteins, affecting their functions and triggering adverse health problems.

The putative interplay between DJ-1/NRF2 and Dimethyl Fumarate: A potentially important pharmacological target

Recent research has outlined that Dimethyl Fumarate (DMF) functions as a gene regulator via multiple pathways, critical among which is the NRF2 cytoprotective cascade. PARK7/DJ-1 is a multifunctional protein that acts as a redox sensor and effector of multiple cytoprotective pathways, including NRF2. Specifically, it prevents the association of NRF2 with its inhibitor KEAP1, allowing NRF2 to enter the nucleus and mediate cytoprotective and antioxidant cascades. It is our hypothesis that while the NRF2-KEAP1 inhibitory complex is reported the main pharmacological target for DMF's NRF dependent functions, no study to date has explored the effects of DMF on DJ-1's expression, and vice-versa, the possibility of a regulatory inadequacy in the upstream, oxidant-responsive DJ-1 activator of the NRF2 cascade.

High expression of DJ-1 promotes growth and invasion via the PTEN-AKT pathway and predicts a poor prognosis in colorectal cancer

Cancer cell invasion and unlimited proliferation are key factors in patients with colorectal cancer (CRC). Increased protein deglycase DJ-1 in cancer cells is known to promote tumor growth; however, its role in CRC progression is not well defined. In this study, we investigated 100 CRC patients with disease stages I-IV to determine whether DJ-1 could serve as a prognostic biomarker in CRC. These results showed that DJ-1 expression in CRC tissues was higher than that in normal colon tissues and was associated with the (Tumor Node Metastasis) TNM stage. CRC patients with low DJ-1 expression had a longer overall survival than those with high expression, and multivariate and univariate analyses indicated that DJ-1 expression was an independent prognostic factor for overall survival in CRC. Furthermore, DJ-1 overexpression in two colon cancer cell lines, HCT116 and SW480, activated protein kinase AKT and downregulated tumor suppressor PTEN, whereas DJ-1 knockdown upregulated PTEN expression and effectively suppressed CRC cell invasion and proliferation both in vitro and in vivo, revealing a mechanism underlying DJ-1 pro-oncogenic activity in CRC. Treatment of MK2206, the specific AKT inhibitor, significantly decreased DJ-1-mediated cell proliferation and mobility in vitro. Taken together, these results suggest that DJ-1 may be a novel prognostic biomarker and potential therapeutic target in human CRC.

Effect of DJ-1 Downregulation on the Functions of the First Trimester Extravillous Trophoblasts

DJ-1 ( PARK7) has been reported to be causative gene of Parkinson disease and also an oncogene. A loss in DJ-1 function can lead to cell death in neurodegenerative disease, or a gain of it can cause unregulated cell survival in cancer, respectively. DJ-1 protein is known to be expressed mainly in trophoblastic cells in the placenta with increased expression in the first trimester compared to later in term. However, its role in trophoblast regulation remains unknown. This study aimed to investigate the effect of DJ-1 regulation on a first trimester extravillous trophoblast cell line, HTR-8/SVneo. The effect of DJ-1 downregulation induced by small-interfering RNA on cell apoptosis, migration, and the pathway to regulate the cell function was assessed. Data of this study showed that DJ-1 downregulation increased apoptosis and reduced migration by regulating matrix metalloproteinase 2 and matrix metalloproteinase 9 in HTR-8/SVneo cells under both ambient and oxidative stress. Changes in cell function were demonstrated to be at least partly dependent on the AKT/S6 kinase beta-1 (S6K1) pathway. In summary, DJ-1 might play a protective role in maintaining trophoblastic cell functions through the AKT/S6K1-based pathway.

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 (pH_i ) 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.

Alkaline Cytosolic pH and High Sodium Hydrogen Exchanger 1 (NHE1) Activity in Th9 Cells

CD4⁺ T helper 9 (Th9) cells are a newly discovered Th cell subset that produce the pleiotropic cytokine IL-9. Th9 cells can protect against tumors and provide resistance against helminth infections. Given their pivotal role in the adaptive immune system, understanding Th9 cell development and the regulation of IL-9 production could open novel immunotherapeutic opportunities. The Na⁺/H⁺ exchanger 1 (NHE1; gene name Slc9α1)) is critically important for regulating intracellular pH (pH_i), cell volume, migration, and cell survival. The pH_i influences cytokine secretion, activities of membrane-associated enzymes, ion transport, and other effector signaling molecules such as ATP and Ca²⁺ levels. However, whether NHE1 regulates Th9 cell development or IL-9 secretion has not yet been defined. The present study explored the role of NHE1 in Th9 cell development and function. Th cell subsets were characterized by flow cytometry and pH_i was measured using 2',7'-bis-(2-carboxyethyl)-5-(and-6)-carboxyfluorescein-acetoxymethyl ester (BCECF-AM) dye. NHE1 functional activity was estimated from the rate of realkalinization following an ammonium pulse. Surprisingly, in Th9 cells pH_i and NHE1 activity were significantly higher than in all other Th cell subsets (Th1/Th2/Th17 and induced regulatory T cells (iTregs)). NHE1 transcript levels and protein abundance were significantly higher in Th9 cells than in other Th cell subsets. Inhibition of NHE1 by siRNA-NHE1 or with cariporide in Th9 cells down-regulated IL-9 and ATP production. NHE1 activity, Th9 cell development, and IL-9 production were further blunted by pharmacological inhibition of protein kinase Akt1/Akt2. Our findings reveal that Akt1/Akt2 control of NHE1 could be an important physiological regulator of Th9 cell differentiation, IL-9 secretion, and ATP production.