DJ-1, a novel regulator of the tumor suppressor PTEN

Mitochondrial ATP-Dependent Proteases-Biological Function and Potential Anti-Cancer Targets

Cells must eliminate excess or damaged proteins to maintain protein homeostasis. To ensure protein homeostasis in the cytoplasm, cells rely on the ubiquitin-proteasome system and autophagy. In the mitochondria, protein homeostasis is regulated by mitochondria proteases, including four core ATP-dependent proteases, m-AAA, i-AAA, LonP, and ClpXP, located in the mitochondrial membrane and matrix. This review will discuss the function of mitochondrial proteases, with a focus on ClpXP as a novel therapeutic target for the treatment of malignancy. ClpXP maintains the integrity of the mitochondrial respiratory chain and regulates metabolism by degrading damaged and misfolded mitochondrial proteins. Inhibiting ClpXP genetically or chemically impairs oxidative phosphorylation and is toxic to malignant cells with high ClpXP expression. Likewise, hyperactivating the protease leads to increased degradation of ClpXP substrates and kills cancer cells. Thus, targeting ClpXP through inhibition or hyperactivation may be novel approaches for patients with malignancy.

Mechanism of N-acetylcysteine in alleviating diabetic myocardial ischemia reperfusion injury by regulating PTEN/Akt pathway through promoting DJ-1

Ischemic heart disease is the main cardiovascular complication of diabetes patients which is mainly caused by oxidative stress. DJ-1 is the key regulator for myocardial protection through inhibiting phosphatase and tensin homolog deleted on chromosome 10 (PTEN) and activating Akt (also known as PKB or protein kinase B). This research is to investigate whether the antioxidant N-acetylcysteine (NAC) could alleviate diabetic myocardial ischemia/reperfusion (I/R) injury by the protective molecule DJ-1. DJ-1 in rat myocardial H9c2 cells and cardiac tissue was respectively knocked down by siRNA and adeno-associated virus (AAV). From the present study, it could be found that compared with high glucose (HG)-normal (N)/DM group, hypoxia/reoxygenation (H/R) or I/R injury can aggravate oxidative stress injury and apoptosis rate of myocardial cells, inhibit the expression of Bcl-2, activate the BAX and cleaved caspase-3 (c-caspase-3) protein and PTEN/Akt pathway. However, in the groups of HG-N, DM, HG-N+I/R and DM+I/R, NAC can significantly reduce oxidative stress injury and apoptosis rate of myocytes, promote the Bcl-2 and DJ-1 molecules, inhibit BAX and c-caspase-3 protein and PTEN/Akt pathway. Compared with HG-N+I/R+NAC and DM+I/R+NAC groups, the oxidative stress injury, apoptosis rate of myocardial cells and heart tissues increased after the knockdown of DJ-1, the expression of Bcl-2 and DJ-1 were inhibited, the BAX and c-caspase-3 expression was increased, and PTEN/Akt pathway was activated. Taken together, the findings suggest that NAC can reduce I/R injury in diabetic myocardium by up-regulating the PTEN/Akt pathway through the level of DJ-1.

The cell biology of Parkinson's disease

Parkinson's disease (PD) is a progressive neurodegenerative disorder resulting from the death of dopamine neurons in the substantia nigra pars compacta. Our understanding of PD biology has been enriched by the identification of genes involved in its rare, inheritable forms, termed PARK genes. These genes encode proteins including α-syn, LRRK2, VPS35, parkin, PINK1, and DJ1, which can cause monogenetic PD when mutated. Investigating the cellular functions of these proteins has been instrumental in identifying signaling pathways that mediate pathology in PD and neuroprotective mechanisms active during homeostatic and pathological conditions. It is now evident that many PD-associated proteins perform multiple functions in PD-associated signaling pathways in neurons. Furthermore, several PARK proteins contribute to non-cell-autonomous mechanisms of neuron death, such as neuroinflammation. A comprehensive understanding of cell-autonomous and non-cell-autonomous pathways involved in PD is essential for developing therapeutics that may slow or halt its progression.

Alterations of Nigral Dopamine Levels in Parkinson's Disease after Environmental Enrichment and PACAP Treatment in Aging Rats

The neuroprotective effects of environmental enrichment and PACAP (pituitary adenylate cyclase-activating polypeptide) are well-described in Parkinson’s disease. The aim of our study is to investigate the beneficial effects of these factors in aging parkinsonian rats. Newborn Wistar rats were divided into standard and enriched groups according to their environmental conditions. Standard animals were raised under regular conditions. During the first five postnatal weeks, enriched pups were placed in larger cages with different objects. Aging animals received (1) saline, (2) 6-hydroxidopamine (6-OHDA), or (3) 6-OHDA + PACAP injections into the left substantia nigra (s.n.). On the seventh postoperative day, the left and right s.n. were collected. The s.n. of young and aging unoperated animals were also examined in our experiment. We determined the dopamine (DA) levels by the HPLC-MS technique, while the sandwich ELISA method was used to measure the Parkinson disease protein 7 (PARK7) protein levels. In healthy animals, we found an age-related decrease of DA levels. In aging parkinsonian-enriched rats, the operation did not result in a significant DA loss. PACAP treatment could prevent the DA loss in both the standard and enriched groups. All injured PACAP-treated rats showed remarkably higher protective PARK7 levels. The protective effect of PACAP correlated with the increase of the DA and PARK7 levels.

Cancer and Parkinson's Disease: Common Targets, Emerging Hopes

Cancer and neurodegeneration are two major leading causes of morbidity and death worldwide. At first sight, the two fields do not seem to share much in common and, if anything, might be placed on opposite ends of a spectrum. Although neurodegeneration results in excessive neuronal cell death, cancer emerges from increased proliferation and resistance to cell death. Therefore, one might expect significant differences in the underlying pathophysiological mechanisms. However, the more we deepen our understanding of these two types of diseases, the more we appreciate the unexpected overlap between them. Although most epidemiological studies support an inverse association between the risk for development of neurodegenerative diseases and cancer, increasing evidence points to a positive correlation between specific types of cancer, like melanoma, and neurodegenerative diseases, like Parkinson's disease (PD). We believe that deciphering the molecular processes and pathways underlying one of these diseases may significantly increase our understanding about the other. Therefore, the identification of novel biomarkers and therapeutic approaches in cancer, may lead to improved diagnosis and treatment of neurodegeneration, and vice versa. In this Viewpoint, we summarize recent findings connecting both diseases and speculate that insights from one disease may inform on mechanisms, and help identify novel biomarkers and targets for intervention, possibly leading to improved management of both diseases. © 2020 International Parkinson and Movement Disorder Society.

DJ-1 is involved in the multidrug resistance of SGC7901 gastric cancer cells through PTEN/PI3K/Akt/Nrf2 pathway

Gastric cancer is a common malignancy worldwide. The occurrence of multidrug resistance (MDR) is the major obstacle for effective gastric cancer chemotherapy. In this study, the in-depth molecular mechanism of the DJ-1-induced MDR in SGC7901 gastric cancer cells was investigated. The results showed that DJ-1 expression level was higher in MDR variant SGC7901/VCR cells than that in its parental SGC7901 cells. Moreover, DJ-1 overexpression conferred the MDR phenotype to SGC7901 cells, while DJ-1 knockdown in SGC7901/VCR cells induced re-sensitization to adriamycin, vincristine, cisplatin, and 5-fluorouracil. These results suggested that DJ-1 mediated the development of MDR in SGC7901 gastric cancer cells. Importantly, further data revealed that the activation of PI3k/Akt and Nrf2 signaling pathway were required for the DJ-1-induced MDR phenotype in SGC7901 gastric cancer cells. Meanwhile, we found that PI3k/Akt pathway was activated probably through DJ-1 directly binding to and negatively regulating PTEN, consequently resulting in Nrf2 phosphorylation and activation, and thereby inducing Nrf2-dependent P-glycoprotein (P-gp) and Bcl-2 expressions in the DJ-1-mediated MDR of SGC7901 gastric cancer cells. Overall, these results revealed that activating PTEN/PI3K/Akt/Nrf2 pathway and subsequently upregulating P-gp and Bcl-2 expression could be a critical mechanism by which DJ-1 mediates the development of MDR in SGC7901 gastric cancer cells. The new findings may be helpful for understanding the mechanisms of MDR in gastric cancer cells, prompting its further investigation as a molecular target to overcome MDR.

PARK7 maintains the stemness of glioblastoma stem cells by stabilizing epidermal growth factor receptor variant III

PARK7 is involved in many key cellular processes, including cell proliferation, transcriptional regulation, cellular differentiation, oxidative stress protection, and mitochondrial function maintenance. Deregulation of PARK7 has been implicated in the pathogenesis of various human diseases, including cancer. Here, we aimed to clarify the effect of PARK7 on stemness and radioresistance of glioblastoma stem cells (GSCs). Serum differentiation and magnetic cell sorting of GSCs revealed that PARK7 was preferentially expressed in GSCs rather than differentiated GSCs. Immunohistochemical staining showed enhanced expression of PARK7 in glioma tissues compared to that in normal brain tissues. shRNA-mediated knockdown of PARK7 inhibited the self-renewal activity of GSCs in vitro, as evidenced by the results of neurosphere formation, limiting dilution, and soft-agar clonogenic assays. In addition, PARK7 knockdown suppressed GSC invasion and enhanced GSC sensitivity to ionizing radiation (IR). PARK7 knockdown suppressed expression of GSC signatures including nestin, epidermal growth factor receptor variant III (EGFRvIII), SOX2, NOTCH1, and OCT4. Contrarily, overexpression of PARK7 in CD133^- non-GSCs increased self-renewal activities, migration, and IR resistance, and rescued the reduction of GSC factors under shPARK7-transfected and serum-differentiation conditions. Intriguingly, PARK7 acted as a co-chaperone of HSP90 by binding to it, protecting EGFRvIII from proteasomal degradation. Knockdown of PARK7 increased the production of reactive oxygen species, inducing partial apoptosis and enhancing IR sensitivity in GSCs. Finally, PARK7 knockdown increased mouse survival and IR sensitivity in vivo. Based on these data, we propose that PARK7 plays a pivotal role in the maintenance of stemness and therapeutic resistance in GSCs.

Approaches to Investigating the Protein Interactome of PTEN

The tumor suppressor phosphatase and tensin homologue (PTEN) is a redox-sensitive dual specificity phosphatase with an essential role in the negative regulation of the PI3K-AKT signaling pathway, affecting metabolic and cell survival processes. PTEN is commonly mutated in cancer, and dysregulation in the metabolism of PIP₃ is implicated in other diseases such as diabetes. PTEN interactors are responsible for some functional roles of PTEN beyond the negative regulation of the PI3K pathway and are thus of great importance in cell biology. Both high-data content proteomics-based approaches and low-data content PPI approaches have been used to investigate the interactome of PTEN and elucidate further functions of PTEN. While low-data content approaches rely on co-immunoprecipitation and Western blotting, and as such require previously generated hypotheses, high-data content approaches such as affinity pull-down proteomic assays or the yeast 2-hybrid system are hypothesis generating. This review provides an overview of the PTEN interactome, including redox effects, and critically appraises the methods and results of high-data content investigations into the global interactome of PTEN. The biological significance of findings from recent studies is discussed and illustrates the breadth of cellular functions of PTEN that can be discovered by these approaches.

Machine learning discriminates a movement disorder in a zebrafish model of Parkinson's disease

Animal models of human disease provide an in vivo system that can reveal molecular mechanisms by which mutations cause pathology, and, moreover, have the potential to provide a valuable tool for drug development. Here, we have developed a zebrafish model of Parkinson's disease (PD) together with a novel method to screen for movement disorders in adult fish, pioneering a more efficient drug-testing route. Mutation of the PARK7 gene (which encodes DJ-1) is known to cause monogenic autosomal recessive PD in humans, and, using CRISPR/Cas9 gene editing, we generated a Dj-1 loss-of-function zebrafish with molecular hallmarks of PD. To establish whether there is a human-relevant parkinsonian phenotype in our model, we adapted proven tools used to diagnose PD in clinics and developed a novel and unbiased computational method to classify movement disorders in adult zebrafish. Using high-resolution video capture and machine learning, we extracted novel features of movement from continuous data streams and used an evolutionary algorithm to classify parkinsonian fish. This method will be widely applicable for assessing zebrafish models of human motor diseases and provide a valuable asset for the therapeutics pipeline. In addition, interrogation of RNA-seq data indicate metabolic reprogramming of brains in the absence of Dj-1, adding to growing evidence that disruption of bioenergetics is a key feature of neurodegeneration.This article has an associated First Person interview with the first author of the paper.

Upregulation of DJ-1 expression in melanoma regulates PTEN/AKT pathway for cell survival and migration

Cutaneous melanoma is known to be one of the most dangerous skin cancers because of its metastatic functions. Today, it is essential to investigate specific biomarkers for the target treatment in many diseases including cancers. DJ-1 protein, also known as Parkinson disease 7, has various functions associated with cancer progression including cell survival and migration. Phosphatase and tensin homolog (PTEN) is a tumor suppressor that regulates the PI3K/AKT signaling pathway and its mutations have been reported to frequently occur in many cancers such as thyroid, breast and skin. Recently, DJ-1 has been identified as a negative regulator of PTEN in many human cancer cells. However, the impacts and relationship of DJ-1 and PTEN have not been studied yet in melanoma. To confirm the expression of DJ-1 and PTEN in melanoma compared to normal skin tissues and find out functions of DJ-1 in melanoma cells, Western blot analysis and immunohistochemical staining were used. Transfection of G361 cells with DJ-1-specific small interfering RNA was performed to figure out the roles of DJ-1 and the relationship between DJ-1 and PTEN in melanoma cells. In our study, the DJ-1 protein was significantly increased with loss of PTEN protein in melanoma compared to that in normal skin. Inhibition of DJ-1 in G361 cells induced apoptosis, and suppressed cell survival and migration. Furthermore, suppression of DJ-1 in G361 cells increased the expression of cleaved caspase-3, cleaved PARP, Bax, p53, and Daxx as well as PTEN, while it decreased expression of survivin, caspase-3, and PARP. Also, downregulated DJ-1 inhibited phosphorylation of AKT in G361 cells. Collectively, DJ-1 overexpression could affect the proliferative and invasive capabilities of melanoma cells via regulating the PTEN/AKT pathway and apoptosis-related proteins. This study suggests that DJ-1 may be a potential target for the treatment of melanoma.

Overexpression of DJ-1 alleviates autosomal dominant polycystic kidney disease by regulating cell proliferation, apoptosis, and mitochondrial metabolism in vitro and in vivo

BACKGROUND

DJ-1 is critical for the mitochondrial function associated with autosomal dominant polycystic kidney disease (ADPKD). We aimed to investigate DJ-1's function in the pathogenesis of ADPKD.

METHODS

DJ-1 was knocked-down in IMCD3 cells to evaluate the effects of DJ-1 on cell phenotype and mitochondrial function in vitro. Furthermore, we generated three groups of mice with different expression levels of DJ-1 within an established ADPKD model: ADPKD, ADPKDpcDNA, and ADPKDpcDNA-DJ-1.

RESULTS

DJ-1 knock-down significantly increased oxidative stress as well as the proliferation and apoptosis rate of IMCD3 cells, along with Bcl-2 down-regulation and the up-regulation of Ki67, PCNA, Bax, cleaved caspase-3, and cleaved caspase-9. DJ-1 knock-down suppressed the cellular respiration, Ca2+ absorption, and mitochondrial complex I activity in mitochondria. In vivo, we verified that DJ-1 was down-regulated in ADPKD models, and its overexpression attenuated the renal dysfunction in ADPKD models. The transgenic mice had a significantly smaller renal cyst and less interstitial fibrosis than control, accompanied byα-SMA, fibronectin, and TGF-β1 up-regulation. Moreover, in vivo results confirmed DJ-1 overexpression inhibited the proliferation and apoptosis of tubular epithelial cells along with down-regulation of Ki67, PCNA, p53, intracellular Cyt c, cleaved caspase-3, and cleaved caspase-9 and the up-regulation of Bcl-2.

CONCLUSIONS

DJ-1 was down-regulated in ADPKD models, and its overexpression may attenuate the renal dysfunction and pathological damage by regulating the proliferation, apoptosis, oxidative stress and mitochondrial metabolism, which may be mediated by the p53 signaling pathway.

GDNF/RET signaling in dopamine neurons in vivo

The glial cell line-derived neurotrophic factor (GDNF) and its canonical receptor Ret can signal both in tandem and separately to exert many vital functions in the midbrain dopamine system. It is known that Ret has effects on maintenance, physiology, protection and regeneration in the midbrain dopamine system, with the physiological functions of GDNF still somewhat unclear. Notwithstanding, Ret ligands, such as GDNF, are considered as promising candidates for neuroprotection and/or regeneration in Parkinson's disease, although data from clinical trials are so far inconclusive. In this review, we discuss the current knowledge of GDNF/Ret signaling in the dopamine system in vivo as well as crosstalk with pathology-associated proteins and their signaling in mammals.

Association between a DJ-1 polymorphism and the risk of Parkinson's disease: a PRISMA-compliant systematic review and meta-analysis

Objective

In recent years, a number of case–control studies have focused on the association between the DJ-1 g.168_185del polymorphism and the risk of Parkinson's disease (PD). However, the results have been conflicting. To estimate the relationship between the DJ-1 g.168_185del polymorphism and PD susceptibility, a comprehensive meta-analysis was performed.

Methods

Eligible studies concerning the DJ-1 g.168_185del polymorphism and PD susceptibility were searched for in the PubMed, Web of Science, Embase, Wanfang, CNKI, and VIP databases. Odds ratios and 95% confidence intervals were calculated to estimate the strength of the associations. In total, 11 studies were included in this meta-analysis, including 13 case–control studies with 2890 cases and 3043 controls.

Results

This meta-analysis revealed that DJ-1 g.168_185del variants are associated with PD susceptibility in the non-Asian population, but not in the Asian population.

Conclusions

Our meta-analysis suggests that DJ-1 gene variants are not associated with the risk of PD in the overall population.

Bidirectional Relation Between Parkinson's Disease and Glioblastoma Multiforme

Cancer and Parkinson's disease (PD) define two disease entities that include opposite concepts. Indeed, the involved mechanisms are at different ends of a spectrum related to cell survival - one due to enhanced cellular proliferation and the other due to premature cell death. There is increasing evidence indicating that patients with neurodegenerative diseases like PD have a reduced incidence for most cancers. In support, epidemiological studies demonstrate an inverse association between PD and cancer. Both conditions apparently can involve the same set of genes, however, in affected tissues the expression was inversely regulated: genes that are down-regulated in PD were found to be up-regulated in cancer and vice versa, for example p53 or PARK7. When comparing glioblastoma multiforme (GBM), a malignant brain tumor with poor overall survival, with PD, astrocytes are dysregulated in both diseases in opposite ways. In addition, common genes, that are involved in both diseases and share common key pathways of cell proliferation and metabolism, were shown to be oppositely deregulated in PD and GBM. Here, we provide an overview of the involvement of PD- and GBM-associated genes in common pathways that are dysregulated in both conditions. Moreover, we illustrate why the simultaneous study of PD and GBM regarding the role of common pathways may lead to a deeper understanding of these still incurable conditions. Eventually, considering the inverse regulation of certain genes in PD and GBM will help to understand their mechanistic basis, and thus to define novel target-based strategies for causative treatments.

[Research on Analysis of Final Diagnosis and Prognostic Factors, and Development of New Therapeutic Drugs for Malignant Tumors (Especially Malignant Pediatric Tumors)]

Outcomes of treatment for malignant pediatric tumors including leukemia are improving by conventional multimodal treatment with strong chemotherapy, surgical resection, radiotherapy, and bone marrow transplantation. However, patients with advanced neuroblastoma, metastatic Ewing's sarcoma family of tumor (ESFT), and metastatic osteosarcoma continue to have an extremely poor prognosis. Therefore novel therapeutic strategies are urgently needed to improve their survival. Apoptotic cell death is a key mechanism for normal cellular homeostasis. Intact apoptotic mechanisms are pivotal for embryonic development, tissue remodeling, immune regulation, and tumor regression. Genetic aberrations disrupting programmed cell death often underpin tumorigenesis and drug resistance. Moreover, it has been suggested that apoptosis or cell differentiation proceeds to spontaneous regression in early stage neuroblastoma. Therefore apoptosis or cell differentiation is a critical event in this cancer. We extracted many compounds from natural plants (Angelica keiskei, Alpinia officiarum, Lycaria puchury-major, Brassica rapa) or synthesized cyclophane pyridine, indirubin derivatives, vitamin K3 derivatives, burchellin derivatives, and GANT61, and examined their effects on apoptosis, cell differentiation, and cell cycle in neuroblastoma and ESFT cell lines compared with normal cells. Some compounds were very effective against these tumor cells. These results suggest that they may be applicable as an efficacious and safe drug for the treatment of malignant pediatric tumors.

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.

NRF2 Regulation Processes as a Source of Potential Drug Targets against Neurodegenerative Diseases

NRF2 acts by controlling gene expression, being the master regulator of the Phase II antioxidant response, and also being key to the control of neuroinflammation. NRF2 activity is regulated at several levels, including protein degradation by the proteasome, transcription, and post-transcription. The purpose of this review is to offer a concise and critical overview of the main mechanisms of NRF2 regulation and their actual or potential use as targets for the treatment of neurodegenerative diseases.

DJ-1 promotes epithelial-to-mesenchymal transition via enhancing FGF9 expression in colorectal cancer

Tumor metastasis is the main contributor to high recurrence and mortality in colorectal cancer (CRC). In a previous study, we found that DJ-1 plays an important role in CRC metastasis, and is the main target in Ciclopirox olamine (CPX)-treated CRC. However, the mechanism underlying DJ-1-induced CRC metastasis remains elusive. In the present study, our results showed that DJ-1 could activate Wnt signaling resulting in enhanced invasive potential and epithelial-to-mesenchymal transition (EMT) in CRC cells. RNA-seq and bioinformatics analysis reveals that the DJ-1/Wnt signaling pathway may promote CRC cells' EMT by regulating fibroblast growth factor 9 (FGF9) expression. Molecular validation showed that expression of FGF9 was upregulated by the DJ-1/Wnt signaling pathway and decreasing FGF9-expression impeded DJ-1-induced CRC invasive ability and EMT, suggesting that FGF9 is involved in DJ-1-enhanced CRC metastasis. In addition, we show that FGF9 was overexpressed in CRC human specimens and was significantly associated with tumor differentiation. High FGF9 expression was correlated with worse overall survival, and a correlation exhibited between FGF9 and EMT markers (E-cadherin and Vimentin) in CRC samples. Together, our results determined that FGF9 was involved in DJ-1-induced invasion and EMT in CRC cells, and may represent a promising therapeutic candidate for CRC anti-metastatic strategies.

Mitochondrial dysfunction plays a key role in the development of neurodegenerative diseases in diabetes

Mitochondria have an essential function in cell survival due to their role in bioenergetics, reactive oxygen species generation, calcium buffering, and other metabolic activities. Mitochondrial dysfunctions are commonly found in neurodegenerative diseases (NDs), and diabetes is a risk factor for NDs. However, the role of mitochondria in diabetic neurodegeneration is still unclear. In the present study, we review the latest evidence on the role of mitochondrial dysfunctions in the development of diabetes-related NDs and the underlying molecular mechanisms. Hypoglycemic agents, especially metformin, have been proven to have neuroprotective effects in the treatment of diabetes, in which mitochondria could act as one of the underlying mechanisms. Other hypoglycemic agents, including thiazolidinediones (TZDs), dipeptidyl peptidase 4 (DPP-4) inhibitors, and glucagon-like peptide 1 (GLP-1) receptor agonists, have gained more attention because of their beneficial effects on NDs, presumably by improving mitochondrial function. Our review highlights the notion that mitochondria could be a promising therapeutic target in the treatment of NDs in patients with diabetes.

Novel Insights into PARK7 (DJ-1), a Potential Anti-Cancer Therapeutic Target, and Implications for Cancer Progression

The expression of PARK7 is upregulated in various types of cancer, suggesting its potential role as a critical regulator of the pathogenesis of cancer and in the treatment of cancer and neurodegenerative diseases, including Parkinson’s disease, Alzheimer’s disease, and Huntington disease. PARK7 activates various intracellular signaling pathways that have been implicated in the induction of tumor progression, which subsequently enhances tumor initiation, continued proliferation, metastasis, recurrence, and resistance to chemotherapy. Additionally, secreted PARK7 has been identified as a high-risk factor for the pathogenesis and survival of various cancers. This review summarizes the current understanding of the correlation between the expression of PARK7 and tumor progression.

DJ‑1 is a new prognostic marker and predicts chemotherapy efficacy in colorectal cancer

Protein/nucleic acid deglycase DJ-1 (DJ-1) is a 20-kDa conserved protein, which belongs to the DJ-1/ThiJ/Pfp I protein superfamily. Immunohistochemistry was performed to investigate the expression of DJ-1 in a colorectal cancer (CRC) tissue microarray containing tumor and corresponding adjacent normal tissues. In the present study, DJ-1 expression was significantly upregulated in CRC cells and tissues, compared with that in normal colon cells and adjacent normal tissues, respectively. In addition, patients with high DJ-1 expression levels had a worse overall survival (OS) compared with patients with low expression levels. Multivariate Cox regression analysis revealed that high DJ-1 expression levels was an independent prognostic factor for patients with CRC. Moreover, DJ-1 was able to regulate the PI3K/Akt/p27/cyclin E and PI3K/Akt/mTOR signaling pathways to promote CRC cell growth and metastasis in vitro and in vivo. In addition, DJ-1 regulated the NF-κB/Snail signaling pathway to induce CRC cell epithelial-mesenchymal transition to promote migration and invasion. Notably, patients receiving LFP treatment (oxaliplatin, 5-FU and tetrahydrofolate) had an increased OS compared with patients who underwent only surgery and low DJ-1 expression levels. The findings from the present study suggest that DJ-1 may serve as a promising prognostic marker and predicts chemotherapy efficacy in patients with CRC.

DJ‑1 promotes cell proliferation and tumor metastasis in esophageal squamous cell carcinoma via the Wnt/β‑catenin signaling pathway

DJ‑1, an oncogene, has been reported to be an independent prognostic indicator of poor survival in patients with esophageal squamous cell carcinoma (ESCC). The aim of the present study was to investigate the role of DJ‑1 in tumor cell proliferation and invasion in ESCC and its underlying mechanisms. It was observed that the expression level of DJ‑1 was upregulated and positively associated with EMT biomarkers in 84 human ESCC tissue specimens. Overexpression and knockdown experiments demonstrated that DJ‑1 was involved in proliferation, migration, invasion and EMT in ECA‑109 cells in vitro and extensive peritoneal seeding in a peritoneal dissemination mice model. Furthermore, the present data revealed that DJ‑1 could activate the Wnt/β‑catenin signaling pathway, which mediates the EMT and metastasis in ESCC. In conclusions, DJ‑1 promoted proliferation, invasion, metastasis and the EMT in ESCC via activation of the Wnt/β‑catenin signal pathway. The present results suggested DJ‑1 could represent a promising therapeutic target for the prevention and treatment of ESCC‑related metastasis.

Overexpression of DJ-1 enhances colorectal cancer cell proliferation through the cyclin-D1/MDM2-p53 signaling pathway

Emerging evidence indicates that DJ-1 is highly expressed in different cancers. It modulates cancer progression, including cell proliferation, cell apoptosis, invasion, and metastasis. However, its role in colorectal cancer (CRC) remains poorly defined. The current study noted increased DJ-1 expression in CRC tumor tissue and found that its expression was closely related to clinical-pathological features. Similarly, DJ-1 increased in CRC cells (SW480, HT-29, Caco-2, LoVo, HCT116, and SW620), and especially in SW480 and HCT116 cells. Functional analyses indicated that overexpression of DJ-1 promoted CRC cell invasion, migration, and proliferation in vitro and in vivo. Mechanistic studies indicated that DJ-1 increased in CRC cell lines, activated specific protein cyclin-D1, and modulated the MDM2/p53 signaling pathway by regulating the levels of the downstream factors Bax, Caspase-3, and Bcl-2, which are related to the cell cycle and apoptosis. Conversely, knockdown of DJ-1 upregulated p53 expression by disrupting the interaction between p53 and MDM2 and inhibiting CRC cell proliferation, revealing the pro-oncogenic mechanism of DJ-1 in CRC. In conclusion, the current findings provide compelling evidence that DJ-1 might be a promoter of CRC cell invasion, proliferation, and migration via the cyclin-D1/MDM2-p53 signaling pathway. Findings also suggest its potential role as a postoperative adjuvant therapy for patients with CRC.

Rosmarinic acid exerts an anticancer effect on osteosarcoma cells by inhibiting DJ-1 via regulation of the PTEN-PI3K-Akt signaling pathway

BACKGROUND

Osteosarcoma is the most common type of primary malignant bone tumor. This disease has exhibited a progressively lower survival rate over the past several decades, which has resulted in it becoming a main cause of death in humans. Rosmarinic acid (RA), a water-soluble polyphenolic phytochemical, exerts powerful anticancer effects against multiple types of cancer; however, its potential effects on osteosarcoma remain unknown. Hence, the present study investigated the efficacy of RA against osteosarcoma and aimed to clarify the mechanisms underlying this process.

METHODS

The effects of RA on cell viability, apoptosis, cell cycle distribution, migration, invasion, and signaling molecules were analyzed by CCK-8 assay, flowcytometric analysis, wound healing assay, Transwell assay, proteomic analysis, and use of shRNAs.

RESULTS

RA exerted anti-proliferation and pro-apoptotic effects on U2OS and MG63 osteosarcoma cells. Apoptosis was induced via extrinsic and intrinsic pathways by increasing the Bax/Bcl-2 ratio, triggering the intracellular production of reactive oxygen species (ROS), reducing the mitochondrial membrane potential (MMP), and upregulating the cleavage rates of caspase-8, caspase-9, and caspase-3. Additionally, RA suppressed the migration and invasion of osteosarcoma cells by inhibiting the expression levels of matrix metalloproteinase-2 and -9 (MMP-2 and -9), which are associated with a weakening of the epithelial-mesenchymal transition (EMT). Moreover, proteomic analyses identified DJ-1 as a potential target for RA. Several studies have indicated an oncogenic role for DJ-1 using knockdowns via the lentiviral-mediated transfection of shRNA, which caused the conspicuous suppression of cell proliferation, migration, and invasion as well as the arrest of cell cycle progression. At the molecular level, the expression levels of DJ-1, p-PI3K, and p-Akt were reduced, whereas the protein levels of phosphatase and tensin homologue (PTEN) were increased.

CONCLUSION

In conjunction with the high levels of DJ-1 expression in osteosarcoma tissues and cell lines, the present results suggested that RA exhibited anticancer effects in osteosarcoma cells by inhibiting DJ-1 via regulation of the PTEN-PI3K-Akt signaling pathway. Therefore, DJ-1 might be a biological target for RA in osteosarcoma cells.

Inhibition of MiR-122 Decreases Cerebral Ischemia-reperfusion Injury by Upregulating DJ-1-Phosphatase and Tensin Homologue Deleted on Chromosome 10 (PTEN)/Phosphonosinol-3 Kinase (PI3K)/AKT

BACKGROUND Ischemia-reperfusion injury is caused by a blood reperfusion injury in ischemic brain tissue, and usually occurs in the treatment stage of ischemic disease, which can aggravate brain tissue injury. MiR-122 is closely related to ischemia-reperfusion injury in the myocardium, kidney, and liver; however, the role in cerebral ischemia-reperfusion injury has not been established. MATERIAL AND METHODS In this study, cerebral ischemia-reperfusion injury was established in a rat model, and the control group was a sham-operated group. After ischemia-reperfusion injury for 6, 12, and 24 hours, brain tissue specimens were collected and the expression of miR-122 and DJ-1 were determined using quantitative real-time polymerase chain reaction. Flow cytometry was used to determine the reactive oxygen species (ROS) content. The modified Neurological Severity Score (mNSS) scale was used to evaluate the sensory and motor function defects of the rats. The malondialdehyde (MDA), superoxide dismutase (SOD), and enzyme activity were determined. The rats in the cerebral ischemia-reperfusion injury model were divided into 2 groups (antagomir-NC group and antagomir miR-122 group). Brain neuron RN-c cells were divided into the following 4 groups: antagomir-NC, antagomir miR-122, pIRES2-blank, and pIRES2-DJ-1. Seventy-two hours after transfection, ischemia-reperfusion treatment was carried out and conventional cultured RN-c cells were used as the control group. Flow cytometry was used to detect apoptosis and western blot was used to detect the expression of DJ-1, PTEN, AKT, and p-AKT. RESULTS The expression of miR-122 increased significantly in the process of ischemia-reperfusion damage after cerebral infarction, while the expression of DJ-1 decreased significantly. Downregulation of miR-122 significantly increased the expression of DJ-1, enhanced the activity of the PTEN/PI3K/AKT pathway, reduced cell apoptosis, and alleviated cerebral ischemia-reperfusion injury. CONCLUSIONS Inhibition of miR-122 can decrease cerebral ischemia-reperfusion injury by upregulating DJ-1-PTEN/PI3K/AKT pathway.

DJ-1 protects retinal pericytes against high glucose-induced oxidative stress through the Nrf2 signaling pathway

Oxidative stress has been associated with the etipathogenesis of Diabetic retinopathy (DR). Studies have shown that DJ-1 plays an important role in regulating the reactive oxygen species (ROS) production and resistance to oxidative stress-induced apoptosis. This study aimed to investigate whether DJ-1 upregulates oxidative stress and prevents damage to retinal capillary pericytes by increasing antioxidant capacity through the Nuclear factor erythroid 2-related factor 2 (Nrf2) signaling pathway. Nrf2 is a redox-sensitive transcription factor that encode antioxidant enzymes and phase II metabolic enzymes, activation of Nrf2 functions is one of the critical defensive mechanisms against oxidative stress in many tissues. Our results showed after DJ-1 overexpression, apoptosis of rat retinal pericytes (RRPs) decreased, the ratio of B-cell lymphoma-2 (Bcl-2) to BCL2-Associated X Protein (BAX) increased, the production of ROS decreased, and the protein expression and activity of manganese superoxide dismutase (MnSOD, also called SOD2) and catalase (CAT) increased. DJ-1 overexpression activated Nrf2 expression, however, after Nrf2 silencing, apoptosis of RRPs increased, the ratio of Bcl-2 to BAX decreased, the production of ROS increased, the protein expression of MnSOD and CAT decreased, and the expression of heme oxygenase-1 (HO-1), NADP(H) quinone oxidoreductase (NQO1), glutamate-cysteine ligase catalytic subunit (GCLC) and modifier subunit (GCLM) decreased. These data suggest that enhancement of the Nrf2 pathway is a potential protective strategy for the treatment of DR. Therefore, DJ-1 may prevent high glucose-induced oxidative stress and RRPs apoptosis through the Nrf2 signaling pathway, thereby preventing the early onset and progression of DR.

Dysregulated Interorganellar Crosstalk of Mitochondria in the Pathogenesis of Parkinson's Disease

The pathogenesis of Parkinson’s disease (PD), the second most common neurodegenerative disorder, is complex and involves the impairment of crucial intracellular physiological processes. Importantly, in addition to abnormal α-synuclein aggregation, the dysfunction of various mitochondria-dependent processes has been prominently implicated in PD pathogenesis. Besides the long-known loss of the organelles’ bioenergetics function resulting in diminished ATP synthesis, more recent studies in the field have increasingly focused on compromised mitochondrial quality control as well as impaired biochemical processes specifically localized to ER–mitochondria interfaces (such as lipid biosynthesis and calcium homeostasis). In this review, we will discuss how dysregulated mitochondrial crosstalk with other organelles contributes to PD pathogenesis.

The Parkinson's disease gene PINK1 activates Akt via PINK1 kinase-dependent regulation of the phospholipid PI(3,4,5)P3

Akt signalling is central to cell survival, metabolism, protein and lipid homeostasis, and is impaired in Parkinson's disease (PD). Akt activation is reduced in the brain in PD, and by many PD-causing genes, including PINK1 This study investigated the mechanisms by which PINK1 regulates Akt signalling. Our results reveal for the first time that PINK1 constitutively activates Akt in a PINK1-kinase dependent manner in the absence of growth factors, and enhances Akt activation in normal growth medium. In PINK1-modified MEFs, agonist-induced Akt signalling failed in the absence of PINK1, due to PINK1 kinase-dependent increases in PI(3,4,5)P₃ at both plasma membrane and Golgi being significantly impaired. In the absence of PINK1, PI(3,4,5)P₃ levels did not increase in the Golgi, and there was significant Golgi fragmentation, a recognised characteristic of PD neuropathology. PINK1 kinase activity protected the Golgi from fragmentation in an Akt-dependent fashion. This study demonstrates a new role for PINK1 as a primary upstream activator of Akt via PINK1 kinase-dependent regulation of its primary activator PI(3,4,5)P₃, providing novel mechanistic information on how loss of PINK1 impairs Akt signalling in PD.This article has an associated First Person interview with the first author of the paper.

CPX Targeting DJ-1 Triggers ROS-induced Cell Death and Protective Autophagy in Colorectal Cancer

Rationale: Colorectal cancer (CRC) is one of the most common cancers worldwide. Ciclopirox olamine (CPX) has recently been identified to be a promising anticancer candidate; however, novel activities and detailed mechanisms remain to be uncovered.

Methods: The cytotoxic potential of CPX towards CRC cells was examined in vitro and in vivo. The global gene expression pattern, ROS levels, mitochondrial function, autophagy, apoptosis, etc. were determined between control and CPX-treated CRC cells.

Results: We found that CPX inhibited CRC growth by inhibiting proliferation and inducing apoptosis both in vitro and in vivo. The anti-cancer effects of CPX involved the downregulation of DJ-1, and overexpression of DJ-1 could reverse the cytotoxic effect of CPX on CRC cells. The loss of DJ-1 resulted in mitochondrial dysfunction and ROS accumulation, thus leading to CRC growth inhibition. The cytoprotective autophagy was provoked simultaneously, and blocking autophagy pharmacologically or genetically could further enhance the anti-cancer efficacy of CPX.

Conclusion: Our study demonstrates that DJ-1 loss-induced ROS accumulation plays a pivotal role in CPX-mediated CRC inhibition, providing a further understanding for CRC treatment via modulating compensatory protective autophagy.

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.

Cistanche extracts ameliorates the neurotoxicity induced by hydrogen peroxide in new mutant DJ-1-transfected neuroblastoma cellular models

INTRODUCTION

DJ-1 mutation is a causative reason for familial Parkinson's disease (PD). Leucine166Proline (L166P) and C106S are two important DJ-1 mutations. In this study, we established hydrogen peroxide (H₂ O₂ ) induced L166P and C106S DJ-1-transfected neuroblastoma (SH-SY5Y) cellular models of PD and investigated the effects of Cistanche extracts and key bioactive compounds, including acteoside, echinacoside, caffeic acid, and Cistanche total glycosides on these two models.

METHODS

After expressing FLAG-tagged L166P and C106S DJ-1 plasmids in Escherichia coli, the expressed plasmids were collected, treated with restriction enzyme, and identified using DNA electrophoresis. After purification, the L166P DJ-1 and C106S DJ-1 plasmids were separately transfected into SH-SY5Y cells using liposomes. Transfected SH-SY5Y cells were detected by western blotting and immunocytochemistry. Cell viability was determined using MTT assay.

RESULTS

Both western blotting and immunocytochemistry showed that L166P and C106S DJ-1 were highly expressed in the transfected SH-SY5Y cells. MTT assays showed that transfection with L166P or C106S DJ-1 reduced the viability of SH-SY5Y cells exposed to H₂ O₂ , as compared to untransfected SH-SY5Y cells. In addition, Cistanche extracts and key bioactive compounds, including acteoside, echinacoside, caffeic acid, and Cistanche total glycosides, significantly inhibited the decreases of cell viability caused by H₂ O₂ in L166P and C106S DJ-1-transfected SH-SY5Y cells.

CONCLUSIONS

These findings suggest that we successfully established sensitive and stable H₂ O₂ induced L166P DJ-1- and C106S DJ-1-transfected SH-SY5Y cell models of PD and Cistanche extracts may thus be useful for treating PD.

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.

Protein Promiscuity in H2O2 Signaling

SIGNIFICANCE

Decrypting the cellular response to oxidative stress relies on a comprehensive understanding of the redox signaling pathways stimulated under oxidizing conditions. Redox signaling events can be divided into upstream sensing of oxidants, midstream redox signaling of protein function, and downstream transcriptional redox regulation. Recent Advances: A more and more accepted theory of hydrogen peroxide (H₂O₂) signaling is that of a thiol peroxidase redox relay, whereby protein thiols with low reactivity toward H₂O₂ are instead oxidized through an oxidative relay with thiol peroxidases.

CRITICAL ISSUES

These ultrareactive thiol peroxidases are the upstream redox sensors, which form the first cellular port of call for H₂O₂. Not all redox-regulated interactions between thiol peroxidases and cellular proteins involve a transfer of oxidative equivalents, and the nature of redox signaling is further complicated through promiscuous functions of redox-regulated "moonlighting" proteins, of which the precise cellular role under oxidative stress can frequently be obscured by "polygamous" interactions. An ultimate goal of redox signaling is to initiate a rapid response, and in contrast to prokaryotic oxidant-responsive transcription factors, mammalian systems have developed redox signaling pathways, which intersect both with kinase-dependent activation of transcription factors, as well as direct oxidative regulation of transcription factors through peroxiredoxin (Prx) redox relays.

FUTURE DIRECTIONS

We highlight that both transcriptional regulation and cell fate can be modulated either through oxidative regulation of kinase pathways, or through distinct redox-dependent associations involving either Prxs or redox-responsive moonlighting proteins with functional promiscuity. These protein associations form systems of crossregulatory networks with multiple nodes of potential oxidative regulation for H₂O₂-mediated signaling.

Reversible histone glycation is associated with disease-related changes in chromatin architecture

Cellular proteins continuously undergo non-enzymatic covalent modifications (NECMs) that accumulate under normal physiological conditions and are stimulated by changes in the cellular microenvironment. Glycation, the hallmark of diabetes, is a prevalent NECM associated with an array of pathologies. Histone proteins are particularly susceptible to NECMs due to their long half-lives and nucleophilic disordered tails that undergo extensive regulatory modifications; however, histone NECMs remain poorly understood. Here we perform a detailed analysis of histone glycation in vitro and in vivo and find it has global ramifications on histone enzymatic PTMs, the assembly and stability of nucleosomes, and chromatin architecture. Importantly, we identify a physiologic regulation mechanism, the enzyme DJ-1, which functions as a potent histone deglycase. Finally, we detect intense histone glycation and DJ-1 overexpression in breast cancer tumors. Collectively, our results suggest an additional mechanism for cellular metabolic damage through epigenetic perturbation, with implications in pathogenesis.

Natrium Benzoate Alleviates Neuronal Apoptosis via the DJ-1-Related Anti-oxidative Stress Pathway Involving Akt Phosphorylation in a Rat Model of Traumatic Spinal Cord Injury

This study aimed to explore the neuroprotective effects and mechanisms of natrium benzoate (NaB) and DJ-1 in attenuating reactive oxygen species (ROS)-induced neuronal apoptosis in traumatic spinal cord injury (t-SCI) in rats. T-SCI was induced by clip compression. The protein expression and neuronal apoptosis was evaluated by Western blotting, double immunofluorescence staining and transmission electron microscope (TEM). ROS level, spinal cord water content (SCWC) and Evans blue (EB) extravasation was also examined. Locomotor function was evaluated by Basso, Beattie, and Bresnahan (BBB) and inclined plane test (IPT) scores. We found that DJ-1 is expressed in spinal cord neurons and increased after t-SCI. At 24 h post-injury, the levels of DJ-1, p-Akt, SOD2, ROS, p-p38 MAPK/p38 MAPK ratio, and CC-3 increased, while the Bcl-2/Bax ratio decreased. NaB upregulated DJ-1, p-Akt, and SOD2, decreased ROS, p-p38 MAPK/p38 MAPK ratio, and CC-3, and increased the Bcl-2/Bax ratio, which were reversed by DJ-1 siRNA. The proportion of CC-3- and TUNEL-positive neurons also increased after t-SCI and was reduced by NaB. These effects were reversed by MK2206. Moreover, the level of oxDJ-1 increased after t-SCI, which was decreased by DJ-1 siRNA, NaB or the combination of them. NaB also reduced mitochondrial vacuolization, SCWC and EB extravasation, and improved locomotor function assessed by the BBB and IPT scores. In conclusion, NaB increased DJ-1, and thus reduced ROS and ROS-induced neuronal apoptosis by promoting Akt phosphorylation in t-SCI rats. NaB shows potential as a therapeutic agent for t-SCI, with DJ-1 as its main target.

miR-125b suppresses oral oncogenicity by targeting the anti-oxidative gene PRXL2A

Oral squamous cell carcinoma (OSCC) is a globally prevalent malignancy. The molecular mechanisms of this cancer are not well understood and acquire elucidation. Peroxiredoxin like 2A (PRXL2A) has been reported to be an antioxidant protein that protects cells from oxidative stress. Our previous study identified an association between PRXL2A upregulation in OSCC and a worse patient prognosis. MicroRNAs (miRNAs) are small non-coding RNAs that are involved in the modulation of biological/pathological properties. The miR-125 family of genes drive pluripotent regulation across a wide variety of cancers. In this study, we identify the oncogenic eligibility of PRXL2A and clarify miR-125b as its upstream regulator. Downregulation of miR-125b can be observed in OSCC tumors. Lower miR-125b expression in tumors results in a worse patient prognosis at the relatively early stage. Reporter assays are able to validate that PRXL2A is a direct target of miR-125b. Exogenous miR-125b expression in OSCC cells results in increased oxidative stress, increased drug sensitivity, and suppressor activity that is paralleled by the knockout of PRXL2A gene. The suppressor activity of miR-125b is able to be rescued by PRXL2A, which suggests the existence of a miR-125b-PRXL2A regulatory axis that is part of OSCC pathogenesis. Nuclear factor-erythroid 2-related factor 2 (NRF2) was found to be a downstream effector of the miR-125b-PRXL2A cascade. As a whole, this study has pinpointed novel clues demonstrating that downregulation of miR-125b suppressor underlies upregulation of PRXL2A in OSCC, and this then protects the affected tumor cells from oxidative stress.

DJ-1 modulates the unfolded protein response and cell death via upregulation of ATF4 following ER stress

The unfolded protein response (UPR) triggered by endoplasmic reticulum (ER) stress is a feature of many neurodegenerative diseases including Alzheimer’s disease, Huntington’s disease and Parkinson’s disease (PD). Although the vast majority of PD is sporadic, mutations in a number of genes including PARK7 which encodes the protein DJ-1 have been linked to early-onset, familial PD. In this regard, both PD of sporadic and genetic origins exhibit markers of ER stress-induced UPR. However, the relationship between pathogenic mutations in PARK7 and ER stress-induced UPR in PD pathogenesis remains unclear. In most contexts, DJ-1 has been shown to protect against neuronal injury. However, we find that DJ-1 deficiency ameliorates death in the context of acute ER stress in vitro and in vivo. DJ-1 loss decreases protein and transcript levels of ATF4, a transcription factor critical to the ER response and reduces the levels of CHOP and BiP, its downstream effectors. The converse is observed with DJ-1 over-expression. Importantly, we find that over-expression of wild-type and PD-associated mutant form of PARK7^L166P, enhances ER stress-induced neuronal death by regulating ATF4 transcription and translation. Our results demonstrate a previously unreported role for wild-type and mutant DJ-1 in the regulation of UPR and provides a potential link to PD pathogenesis.

Reactive oxygen species regulate activity-dependent neuronal plasticity in Drosophila

Reactive oxygen species (ROS) have been extensively studied as damaging agents associated with ageing and neurodegenerative conditions. Their role in the nervous system under non-pathological conditions has remained poorly understood. Working with the Drosophila larval locomotor network, we show that in neurons ROS act as obligate signals required for neuronal activity-dependent structural plasticity, of both pre- and postsynaptic terminals. ROS signaling is also necessary for maintaining evoked synaptic transmission at the neuromuscular junction, and for activity-regulated homeostatic adjustment of motor network output, as measured by larval crawling behavior. We identified the highly conserved Parkinson’s disease-linked protein DJ-1β as a redox sensor in neurons where it regulates structural plasticity, in part via modulation of the PTEN-PI3Kinase pathway. This study provides a new conceptual framework of neuronal ROS as second messengers required for neuronal plasticity and for network tuning, whose dysregulation in the ageing brain and under neurodegenerative conditions may contribute to synaptic dysfunction.

PARK7 regulates inflammation-induced pro-labour mediators in myometrial and amnion cells

Preterm birth is a prevalent cause of neonatal deaths worldwide. Inflammation has been implicated in spontaneous preterm birth involved in the processes of uterine contractility and membrane rupture. Parkinson protein 7 (PARK7) has been found to play an inflammatory role in non-gestational tissues. The aims of this study were to determine the expression of PARK7 in myometrium and fetal membranes with respect to term labour onset and to elucidate the effect of PARK7 silencing in primary myometrium and amnion cells on pro-inflammatory and pro-labour mediators. PARK7 mRNA expression was higher in term myometrium and fetal membranes from women in labour compared to non-labouring samples and in amnion from preterm deliveries with chorioamnionitis. In human primary myometrial cells transfected with PARK7 siRNA (siPARK7), there was a significant decrease in IL1B, TNF, fsl-1 and poly(I:C)-induced expression of pro-inflammatory cytokine IL6, chemokines (CXCL8, CCL2), adhesion molecule ICAM1, prostaglandin PGF_2α and its receptor PTGFR. Similarly, amnion cells transfected with siPARK7 displayed a decrease in IL1B-induced expression of IL6, CXCL8 and ICAM1. In myometrial cells transfected with siPARK7, there was a significant reduction of NF-κB RELA transcriptional activity when stimulated with fsl-1, flagellin and poly(I:C), but not with IL1B or TNF. Collectively, our novel data describe a role for PARK7 in regulating inflammation-induced pro-inflammatory and pro-labour mediators in human myometrial and amnion cells.

Da-Bu-Yin-Wan Improves the Ameliorative Effect of DJ-1 on Mitochondrial Dysfunction Through Augmenting the Akt Phosphorylation in a Cellular Model of Parkinson's Disease

Da-Bu-Yin-Wan (DBYW) is recorded originally in China over six centuries ago, and it is used to treat Parkinson’s disease (PD) clinically in recent decades. DJ-1 is a homodimeric protein linked to early-onset PD, and found in the mitochondria. In addition, DJ-1 could protect the cells by regulating gene transcription and modulating the Akt signal pathways. Therefore, in this research, we aimed to investigate the ameliorative effect of DBYW on mitochondria in the view of the DJ-1 and Akt signaling. Rat adrenal pheochromocytoma cell line PC-12 was transfected with the plasmid pcDNA3-Flag-DJ-1 (pDJ-1). Subsequently, PC-12 cells were exposed to the PD-related mitochondrial toxin (1-methyl-4-phenylpyridinium) without/with the DBYW. After transfected with the plasmid pDJ-1, the 1-methyl-4-phenylpyridinium-induced toxicity was decreased, and the DJ-1 expression in protein level was increased. DJ-1 overexpression not only increased the mitochondrial mass, but also improved the total ATP content. Moreover, Akt phosphorylation was augmented by DJ-1 overexpression. Additionally, DBYW enhanced the above effects. Conclusively, these findings indicate that DBYW promotes the ameliorative effects of DJ-1 on mitochondrial dysfunction at least through augmenting the Akt phosphorylation in 1-methyl-4-phenylpyridinium-treated PC-12 cells.

DJ-1 promotes survival of human colon cancer cells under hypoxia by modulating HIF-1α expression through the PI3K-AKT pathway

Background

Protein/nucleic acid deglycase (DJ-1) and hypoxia-inducible factor-1α (HIF-1α) play significant roles in the progression of various types of cancer and are associated with the phosphatidylinositol 3-kinase (PI3K) pathway. However, their functions in colorectal cancer (CRC) have not been identified. The aim of this study was to analyze the putative signaling pathway encompassing DJ-1, PI3K, and HIF-1α in a series of CRC tissues and cell lines.

Purpose

This study aimed at exploring the expression status of DJ-1 in colon cancer and its role in survival of cancer cell lines.

Methods

The expression and localization of DJ-1, PI3K-p110α, phosphorylated Akt (p-AKT), and HIF-1α were determined by immunohistochemistry in 73 resected CRC tissues. The effect of DJ-1 on cell activity was explored by in vitro knockdown and overexpression experiments in SW480 and HT-29 cells. The cells were treated with a PI3K inhibitor (LY294002 or wortmannin), and p-AKT and HIF-1α protein expression were then analyzed. Apoptosis was analyzed by flow cytometry. The expression levels of several HIF-1 target genes were assessed under hypoxic conditions by reverse transcription-PCR and Western blot. Xenograft tumor growth studies were conducted in DJ-1 knockdown or overexpression cells.

Results

High DJ-1 expression was found in 68.49% (50/73) of CRC tissues and associated with larger tumor size and advanced clinical stages. DJ-1 expression was positively associated with PI3K-p110α, p-AKT, and HIF-1α expression in CRC. HIF-1α and p-AKT protein levels were lower in SW480 and HT-29 cells with stable DJ-1 knockdown than in those with DJ-1 overexpression. PI3K inhibitors almost completely blocked DJ-1-induced AKT phosphorylation. However, the expression of HIF-1α was partially preserved after treatment with PI3K inhibitors. We also show that DJ-1 is necessary for the transcriptional ability of HIF-1α and CRC cell survival after hypoxic stress. Moreover, DJ-1 promoted the growth of established tumor xenografts in nude mice.

Conclusion

Our findings are the first to show that DJ-1 is overexpressed in CRC. We suggest a model in which DJ-1 mediates CRC cell survival by regulating the PI3K-AKT-HIF-1α pathway.

The Interplay among PINK1/PARKIN/Dj-1 Network during Mitochondrial Quality Control in Cancer Biology: Protein Interaction Analysis

PARKIN (E3 ubiquitin ligase PARK2), PINK1 (PTEN induced kinase 1) and DJ-1 (PARK7) are proteins involved in autosomal recessive parkinsonism, and carcinogenic processes. In damaged mitochondria, PINK1’s importing into the inner mitochondrial membrane is prevented, PARKIN presents a partial mitochondrial localization at the outer mitochondrial membrane and DJ-1 relocates to mitochondria when oxidative stress increases. Depletion of these proteins result in abnormal mitochondrial morphology. PINK1, PARKIN, and DJ-1 participate in mitochondrial remodeling and actively regulate mitochondrial quality control. In this review, we highlight that PARKIN, PINK1, and DJ-1 should be regarded as having an important role in Cancer Biology. The STRING database and Gene Ontology (GO) enrichment analysis were performed to consolidate knowledge of well-known protein interactions for PINK1, PARKIN, and DJ-1 and envisage new ones. The enrichment analysis of KEGG pathways showed that the PINK1/PARKIN/DJ-1 network resulted in Parkinson disease as the main feature, while the protein DJ-1 showed enrichment in prostate cancer and p53 signaling pathway. Some predicted transcription factors regulating PINK1, PARK2 (PARKIN) and PARK7 (DJ-1) gene expression are related to cell cycle control. We can therefore suggest that the interplay among PINK1/PARKIN/DJ-1 network during mitochondrial quality control in cancer biology may occur at the transcriptional level. Further analysis, like a systems biology approach, will be helpful in the understanding of PINK1/PARKIN/DJ-1 network.

Discovery and Optimization of Inhibitors of the Parkinson's Disease Associated Protein DJ-1

DJ-1 is a Parkinson's disease associated protein endowed with enzymatic, redox sensing, regulatory, chaperoning, and neuroprotective activities. Although DJ-1 has been vigorously studied for the past decade and a half, its exact role in the progression of the disease remains uncertain. In addition, little is known about the spatiotemporal regulation of DJ-1, or the biochemical basis explaining its numerous biological functions. Progress has been hampered by the lack of inhibitors with precisely known mechanisms of action. Herein, we have employed biophysical methodologies and X-ray crystallography to identify and to optimize a family of compounds inactivating the critical Cys106 residue of human DJ-1. We demonstrate these compounds are potent inhibitors of various activities of DJ-1 in vitro and in cell-based assays. This study reports a new family of DJ-1 inhibitors with a defined mechanism of action, and contributes toward the understanding of the biological function of DJ-1.

Secretome of Undifferentiated Neural Progenitor Cells Induces Histological and Motor Improvements in a Rat Model of Parkinson's Disease

Parkinson's disease (PD) is a progressive neurodegenerative movement disorder that results from the death of dopamine (DA) neurons. Over recent years, differentiated or undifferentiated neural stem cells (NSCs) transplantation has been widely used as a means of cell replacement therapy. However, compelling evidence has brought attention to the array of bioactive molecules produced by stem cells, defined as secretome. As described in the literature, other cell populations have a high‐neurotrophic activity, but little is known about NSCs. Moreover, the exploration of the stem cell secretome is only in its initial stages, particularly as applied to neurodegenerative diseases. Thus, we have characterized the secretome of human neural progenitor cells (hNPCs) through proteomic analysis and investigated its effects in a 6‐hydroxidopamine (6‐OHDA) rat model of PD in comparison with undifferentiated hNPCs transplantation. Results revealed that the injection of hNPCs secretome potentiated the histological recovery of DA neurons when compared to the untreated group 6‐OHDA and those transplanted with cells (hNPCs), thereby supporting the functional motor amelioration of 6‐OHDA PD animals. Additionally, hNPCs secretome proteomic characterization has revealed that these cells have the capacity to secrete a wide range of important molecules with neuroregulatory actions, which are most likely support the effects observed. Overall, we have concluded that the use of hNPCs secretome partially modulate DA neurons cell survival and ameliorate PD animals’ motor deficits, disclosing improved results when compared to cell transplantation approaches, indicating that the secretome itself could represent a route for new therapeutic options for PD regenerative medicine. stem cells translational medicine2018;7:829–838

DJ-1 promotes colorectal cancer progression through activating PLAGL2/Wnt/BMP4 axis

Metastasis remains a big barrier for the clinical treatment of colorectal cancer (CRC). Our previous proteomics analysis identified DJ-1 as a potential metastasis biomarker of CRC. In this study, we found that DJ-1 was upregulated in CRC. The levels of DJ-1 were closely correlated with the depths of invasion and predicted patient outcome. Enforced expression of DJ-1 could enhance CRC proliferation and metastasis in vitro and in vivo by stimulating Wnt-β-catenin signaling. Specifically, DJ-1-induced β-catenin nuclear translocation stimulated TCF transcription activity, which promoted BMP4 expression for CRC cell migration and invasion, and elevated CCND1 expression for CRC cell proliferation, respectively. Furthermore, DJ-1-induced Wnt signaling activation was dependent on PLAGL2 expression. In conclusion, our study demonstrates that DJ-1 can promote CRC metastasis by activating PLAGL2-Wnt-BMP4 axis, suggesting novel therapeutic opportunities for postoperative adjuvant therapy in CRC patients.

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.

Reduction of PINK1 or DJ-1 impair mitochondrial motility in neurites and alter ER-mitochondria contacts

Subcellular distribution of mitochondria in neurons is crucial for meeting the energetic demands, as well as the necessity to buffer Ca²⁺ within the axon, dendrites and synapses. Mitochondrial impairment is an important feature of Parkinson disease (PD), in which both familial parkinsonism genes DJ-1 and PINK1 have a great impact on mitochondrial function. We used differentiated human dopaminergic neuroblastoma cell lines with stable PINK1 or DJ-1 knockdown to study live motility of mitochondria in neurites. The frequency of anterograde and retrograde mitochondrial motility was decreased in PINK1 knockdown cells and the frequency of total mitochondrial motility events was reduced in both cell lines. However, neither the distribution nor the size of mitochondria in the neurites differed from the control cells even after downregulation of the mitochondrial fission protein, Drp1. Furthermore, mitochondria from PINK1 knockdown cells, in which motility was most impaired, had increased levels of GSK3βSer9 and higher release of mitochondrial Ca²⁺ when exposed to CCCP-induced mitochondrial uncoupling. Further analysis of the ER-mitochondria contacts involved in Ca²⁺ shuttling showed that PINK1 knockdown cells had reduced contacts between the two organelles. Our results give new insight on how PINK1 and DJ-1 influence mitochondria, thus providing clues to novel PD therapies.

The Therapeutic Potential of Metformin in Neurodegenerative Diseases

The search for treatments for neurodegenerative diseases is a major concern in light of today's aging population and an increasing burden on individuals, families, and society. Although great advances have been made in the last decades to understand the underlying genetic and biological cause of these diseases, only some symptomatic treatments are available. Metformin has long since been used to treat Type 2 Diabetes and has been shown to be beneficial in several other conditions. Metformin is well-tested in vitro and in vivo and an approved compound that targets diverse pathways including mitochondrial energy production and insulin signaling. There is growing evidence for the benefits of metformin to counteract age-related diseases such as cancer, cardiovascular disease, and neurodegenerative diseases. We will discuss evidence showing that certain neurodegenerative diseases and diabetes are explicitly linked and that metformin along with other diabetes drugs can reduce neurological symptoms in some patients and reduce disease phenotypes in animal and cell models. An interesting therapeutic factor might be how metformin is able to balance survival and death signaling in cells through pathways that are commonly associated with neurodegenerative diseases. In healthy neurons, these overarching signals keep energy metabolism, oxidative stress, and proteostasis in check, avoiding the dysfunction and neuronal death that defines neurodegenerative disease. We will discuss the biological mechanisms involved and the relevance of neuronal vulnerability and potential difficulties for future trials and development of therapies.