Protection of pancreatic beta-cells from various stress conditions is mediated by DJ-1

A reduced proteomic signature in critically ill Covid-19 patients determined with plasma antibody micro-array and machine learning

BACKGROUND

COVID-19 is a complex, multi-system disease with varying severity and symptoms. Identifying changes in critically ill COVID-19 patients' proteomes enables a better understanding of markers associated with susceptibility, symptoms, and treatment. We performed plasma antibody microarray and machine learning analyses to identify novel proteins of COVID-19.

METHODS

A case-control study comparing the concentration of 2000 plasma proteins in age- and sex-matched COVID-19 inpatients, non-COVID-19 sepsis controls, and healthy control subjects. Machine learning was used to identify a unique proteome signature in COVID-19 patients. Protein expression was correlated with clinically relevant variables and analyzed for temporal changes over hospitalization days 1, 3, 7, and 10. Expert-curated protein expression information was analyzed with Natural language processing (NLP) to determine organ- and cell-specific expression.

RESULTS

Machine learning identified a 28-protein model that accurately differentiated COVID-19 patients from ICU non-COVID-19 patients (accuracy = 0.89, AUC = 1.00, F1 = 0.89) and healthy controls (accuracy = 0.89, AUC = 1.00, F1 = 0.88). An optimal nine-protein model (PF4V1, NUCB1, CrkL, SerpinD1, Fen1, GATA-4, ProSAAS, PARK7, and NET1) maintained high classification ability. Specific proteins correlated with hemoglobin, coagulation factors, hypertension, and high-flow nasal cannula intervention (P < 0.01). Time-course analysis of the 28 leading proteins demonstrated no significant temporal changes within the COVID-19 cohort. NLP analysis identified multi-system expression of the key proteins, with the digestive and nervous systems being the leading systems.

CONCLUSIONS

The plasma proteome of critically ill COVID-19 patients was distinguishable from that of non-COVID-19 sepsis controls and healthy control subjects. The leading 28 proteins and their subset of 9 proteins yielded accurate classification models and are expressed in multiple organ systems. The identified COVID-19 proteomic signature helps elucidate COVID-19 pathophysiology and may guide future COVID-19 treatment development.

A Systematic Review of Proteomics in Obesity: Unpacking the Molecular Puzzle

PURPOSE OF REVIEW

The present study aims to review the existing literature to identify pathophysiological proteins in obesity by conducting a systematic review of proteomics studies. Proteomics may reveal the mechanisms of obesity development and clarify the links between obesity and related diseases, improving our comprehension of obesity and its clinical implications.

RECENT FINDINGS

Most of the molecular events implicated in obesity development remain incomplete. Proteomics stands as a powerful tool for elucidating the intricate interactions among proteins in the context of obesity. This methodology has the potential to identify proteins involved in pathological processes and to evaluate changes in protein abundance during obesity development, contributing to the identification of early disease predisposition, monitoring the effectiveness of interventions and improving disease management overall. Despite many non-targeted proteomic studies exploring obesity, a comprehensive and up-to-date systematic review of the molecular events implicated in obesity development is lacking. The lack of such a review presents a significant challenge for researchers trying to interpret the existing literature. This systematic review was conducted following the PRISMA guidelines and included sixteen human proteomic studies, each of which delineated proteins exhibiting significant alterations in obesity. A total of 41 proteins were reported to be altered in obesity by at least two or more studies. These proteins were involved in metabolic pathways, oxidative stress responses, inflammatory processes, protein folding, coagulation, as well as structure/cytoskeleton. Many of the identified proteomic biomarkers of obesity have also been reported to be dysregulated in obesity-related disease. Among them, seven proteins, which belong to metabolic pathways (aldehyde dehydrogenase and apolipoprotein A1), the chaperone family (albumin, heat shock protein beta 1, protein disulfide-isomerase A3) and oxidative stress and inflammation proteins (catalase and complement C3), could potentially serve as biomarkers for the progression of obesity and the development of comorbidities, contributing to personalized medicine in the field of obesity. Our systematic review in proteomics represents a substantial step forward in unravelling the complexities of protein alterations associated with obesity. It provides valuable insights into the pathophysiological mechanisms underlying obesity, thereby opening avenues for the discovery of potential biomarkers and the development of personalized medicine in obesity.

Camel whey protein (CWP) ameliorates liver injury in type 2 diabetes mellitus rats and insulin resistance (IR) in HepG2 cells via activation of the PI3K/Akt signaling pathway

This research investigated the effects of camel whey protein (CWP) treatment on type 2 diabetes mellitus (T2DM) rats and insulin resistance (IR) HepG2 cell models. Body weight and fasting blood glucose were observed in type 2 diabetes mellitus (T2DM) rats every week, and biochemical parameters in serum samples were evaluated after 6 weeks. Antioxidant activity in the liver was estimated, and histological examination of the liver tissues was conducted. After CWP treatment, the glucose uptake and lipid accumulation were examined in insulin-resistant HepG2 cells. Our results indicated that CWP mitigated the body weight loss, reversed dyslipidemia, and inhibited the inflammatory response, in T2DM rats. Meanwhile, it protected the liver from being injured by reducing the level of oxidative stress. In the CWP group, the pathological changes were significantly reduced, while the liver lobule structure, liver cell arrangement, as well as congestion, edema, and vacuolization were improved. Our results from quantitative real-time PCR and western blot analyses showed that CWP could up-regulate the expression levels of insulin receptor substrate-2 (IRS-2), phosphoinositide3-kinase (PI3K), protein kinase B (AKT), and glycogen synthase (GS). An active protein component CWP8 was isolated and identified, which was shown to be able to stimulate glycogen synthesis and ameliorate lipid accumulation in IR HepG2 cells. These data indicate that CWP and CWP8 might act as potential natural products regulating glucose and lipid metabolism in T2DM.

Ablation of DJ-1 Enhances Oxidative Stress by Disturbing the Function of Mitochondria in Epidermal Melanocytes

Background

Oxidative stress is implicated in the pathogenesis of vitiligo. The function of DJ-1 in oxidative damage of melanocytes is still elusive.

Aims

The aim of this study was to investigate the role of DJ-1 in oxidative damage of melanocytes.

Material and Methods

The expression of DJ-1 in melanocytes was studied by reverse transcription-quantitative polymerase chain reaction and Western blot. Short-interfering RNAs (siRNA) were employed to downregulate DJ-1. The cells were pooled into three groups: mock group (cells with transfection reagent), negative control (NC) group (negative siRNA control), and siRNA group. After H₂O₂ treatment for 24 h, the morphological changes, cell viability, apoptosis, intracellular reactive oxygen species (ROS) levels, mitochondrial membrane potential (MMP), and mitochondrial respiration were measured in different groups.

Results

DJ-1 was highly expressed in PIG1 melanocytes. DJ-1 knockdown rendered PIG1 melanocytes more susceptible to oxidative stress. Loss of DJ-1 led to apoptosis of PIG1 cells by impairing the function of mitochondria, including morphological abnormalities, ROS accumulation, depolarization of MMP, less adenosine-triphosphate (ATP) production, and less proton leak.

Conclusions

DJ-1 plays a role in maintaining the antioxidative capacity in epidermal melanocytes.

DJ-1 can form β-sheet structured aggregates that co-localize with pathological amyloid deposits

The loss of native function of the DJ-1 protein has been linked to the development of Parkinson's (PD) and other neurodegenerative diseases. Here we show that DJ-1 aggregates into β-sheet structured soluble and fibrillar aggregates in vitro under physiological conditions and that this process is promoted by the oxidation of its catalytic Cys106 residue. This aggregation resulted in the loss of its native biochemical glyoxalase function and in addition oxidized DJ-1 aggregates were observed to localize within Lewy bodies, neurofibrillary tangles and amyloid plaques in human PD and Alzheimer's (AD) patients' post-mortem brain tissue. These findings suggest that the aggregation of DJ-1 may be a critical player in the development of the pathology of PD and AD and demonstrate that loss of DJ-1 function can happen through DJ-1 aggregation. This could then contribute to AD and PD disease onset and progression.

Role of DJ-1 in the mechanism of pathogenesis of Parkinson's disease

DJ-1 protein has multiple specific mechanisms to protect dopaminergic neurons against neurodegeneration in Parkinson's disease. Wild type DJ-1 can acts as oxidative stress sensor and as an antioxidant. DJ-1 exhibits the properties of molecular chaperone, protease, glyoxalase, transcriptional regulator that protects mitochondria from oxidative stress. DJ-1 increases the expression of two mitochondrial uncoupling proteins (UCP 4 and UCP5), that decrease mitochondrial membrane potential and leads to the suppression of ROS production, optimizes of a number of mitochondrial functions, and is regarded as protection for the neuronal cell survival. We discuss also the stabilizing interaction of DJ-1 with the mitochondrial Bcl-xL protein, which regulates the activity of (Inositol trisphosphate receptor) IP₃R, prevents the cytochrome c release from mitochondria and inhibits the apoptosis activation. Upon oxidative stress DJ-1 is able to regulate various transcription factors including nuclear factor Nrf2, PI3K/PKB, and p53 signal pathways. Stress-activated transcription factor Nrf2 regulates the pathways to protect cells against oxidative stress and metabolic pathways initiating the NADPH and ATP production. DJ-1 induces the Nrf2 dissociation from its inhibitor Keap1 (Kelch-like ECH-associated protein 1), promoting Nrf2 nuclear translocation and binding to antioxidant response elements. DJ-1 is shown to be a co-activator of the transcription factor NF-kB. Under nitrosative stress, DJ-1 may regulate PI3K/PKB signaling through PTEN transnitrosylation, which leads to inhibition of phosphatase activity. DJ-1 has a complex modulating effect on the p53 pathway: one side DJ-1 directly binds to p53 to restore its transcriptional activity and on the other hand DJ-1 can stimulate deacylation and suppress p53 transcriptional activity. The ability of the DJ-1 to induce activation of different transcriptional factors and change redox balance protect neurons against aggregation of α-synuclein and oligomer-induced neurodegeneration.

Insulin signaling pathway protects neuronal cell lines by Sirt3 mediated IRS2 activation

Cellular stress like ER and oxidative stress are the principle causative agents of various proteinopathies. Multifunctional protein PARK7/DJ-1 provides protection against cellular stress. Recently, insulin/IGF also has emerged as a neuro-protective molecule. However, it is not known whether DJ-1 and insulin/IGF complement each other for cellular protection in response to stress. In this study, we show for the first time, that in human and mouse neuronal cell lines, down regulation of DJ-1 for 48 h leads to compensatory upregulation of insulin/IGF signaling (IIS) pathway genes, namely, insulin receptor, insulin receptor substrate, and Akt under normal physiological conditions as well as in cellular stress conditions. Moreover, upon exogenous supply of insulin there is a marked increase in the IIS components both at gene and protein levels leading to down regulation and inactivation of GSK3β. By immunoprecipitation, it was observed that Sirt3 mediated deacetylation and activation of FoxO3a could not occur under DJ-1 downregulation. Transient DJ-1 downregulation also led to Akt mediated increased phosphorylation and nuclear exclusion of FoxO3a. When DJ-1 was downregulated increased interaction of Sirt3 with IRS2 was observed leading to its activation resulting in IIS upregulation. Thus, transient downregulation of DJ-1 leads to stimulation of IIS pathway by Sirt3 mediated IRS2 activation. Consequently, antiapoptotic program is triggered in neuronal cells via Akt-GSK3β-FoxO3a axis. © 2018 BioFactors, 44(3):224-236, 2018.

Novel association of DJ-1 with HER3 potentiates HER3 activation and signaling in cancer

HER3/ErbB3 has emerged as a new therapeutic target for cancer. Currently, more than a dozen anti-HER3 antibodies are in clinical trials for treatment of various cancers. However, limited understanding of the complex HER3 signaling in cancer and lack of established biomarkers have made it challenging to stratify cancer patients who can benefit from HER3 targeted therapies. In this study, we identified DJ-1/PARK7 (Parkinson Protein 7) as a novel interaction partner of HER3 and demonstrated the potential of DJ-1 as a biomarker for anti-HER3 cancer therapy. DJ-1 association with HER3 protects HER3 from ubiquitination and degradation through the proteasomal pathway in breast cancer cells. However, neuregulin 1 (NRG-1) mediated HER3 activation results in a reduced association of DJ-1 with HER3. DJ-1 shRNA knockdown in cancer cells resulted in decreased levels of HER3 and its downstream signaling through the PI3K/AKT and Ras/Raf/ERK pathways. DJ-1 shRNA knockdown cancer cells significantly reduced cell proliferation and migration in vitro and tumor growth in vivo. Conversely, overexpression of DJ-1 increased HER3 levels and promoted cancer cell proliferation in vitro and tumor growth in vivo. Notably, cancer cells with high DJ-1 expression showed more sensitivity than DJ-1 knockdown cells to anti-HER3 antibody inhibition. In addition, there was a significant co-expression of HER3 and DJ-1 in tumor tissues of breast cancer patients. Taken together, these results suggest that high DJ-1 expression in breast cancer cells predicts elevated HER3 signaling and may therefore serve as a biomarker for HER3 targeted antibody cancer therapies.

Structural features of human DJ-1 in distinct Cys106 oxidative states and their relevance to its loss of function in disease

DJ-1 (PARK7) is a multifunctional protein linked to the onset and progression of a number of diseases, most of which are associated with high oxidative stress. The Cys106 of DJ-1 is unusually reactive and thus sensitive to oxidation, and due to high oxidative stress it was observed to be in various oxidized states in disease condition. The oxidation state of Cys106 of DJ-1 is believed to determine the specific functions of the protein in normal and disease conditions. Here we report molecular dynamics simulation and biophysical experimental studies on DJ-1 in reduced (Cys106, S^-), oxidized (Cys106, SO₂^-), and over-oxidized (Cys106, SO₃^-) states. To simulate the different oxidation states of Cys106 in DJ-1, AMBER related force field parameters were developed and reported for 3-sulfinoalanine and cysteine sulfonic acid. Our studies found that the overall structure of DJ-1 in different oxidation states was similar globally, while it differed locally significantly, which have implications on its stability, function and its link to disease on-set. Importantly, the results suggest that over-oxidation may trigger loss of functions due to local structural modification in the Cys106 containing pocket of DJ-1 and structurally destabilize the dimeric state of DJ-1, which is believed to be its bioactive conformation. Such loss of functions would result in reduced ability of DJ-1 to protect from oxidative stress insults and may lead to increased progression of disease.

DJ-1 overexpression restores ischaemic post-conditioning-mediated cardioprotection in diabetic rats: role of autophagy

IPO (ischaemic post-conditioning) is a promising method of alleviating myocardial IR (ischaemia-reperfusion) injury; however, IPO-mediated cardioprotection is lost in diabetic hearts via mechanisms that remain largely unclear. We hypothesized that decreased cardiac expression of DJ-1, a positive modulator of autophagy, compromises the effectiveness of IPO-induced cardioprotection in diabetic rats. Diabetic rats subjected to myocardial IR (30 min of coronary artery occlusion followed by 120 min of reperfusion) exhibited more severe myocardial injury, less cardiac autophagy, lower DJ-1 expression and AMPK (adenosine monophosphate-activated protein kinase)/mTOR (mammalian target of rapamycin) pathway activity than non-diabetic rats. IPO significantly attenuated myocardial injury and up-regulated cardiac DJ-1 expression, AMPK/mTOR activity and autophagy in non-diabetic rats but not in diabetic rats. AAV9 (adeno-associated virus 9)-mediated cardiac DJ-1 overexpression as well as pretreatment with the autophagy inducer rapamycin restored IPO-induced cardioprotection in diabetic rats, an effect accompanied by AMPK/mTOR activation and autophagy up-regulation. Combining HPO (hypoxic post-conditioning) with DJ-1 overexpression markedly attenuated HR (hypoxia-reoxygenation) injury in H9c2 cells with high glucose (HG, 30 mM) exposure, accompanied by AMPK/mTOR signalling activation and autophagy up-regulation. The DJ-1 overexpression-mediated preservation of HPO-induced cardioprotection was completely inhibited by the AMPK inhibitor compound C (CC) and the autophagy inhibitor 3-MA (3-methyladenine). Thus, decreased cardiac DJ-1 expression, which results in impaired AMPK/mTOR signalling and decreased autophagy, could be a major mechanism underlying the loss of IPO-induced cardioprotection in diabetes.

The Role of the Antioxidant Protein DJ-1 in Type 2 Diabetes Mellitus

Type 2 diabetes mellitus (T2DM) is a worldwide escalating health disorder resulting from insulin resistance and functional loss of insulin-producing beta cells that finally cause chronically elevated blood glucose concentrations. Here we review the role of ubiquitously expressed antioxidant protein DJ-1 in the pathogenesis of T2DM. In beta cells, DJ-1 protects against oxidative stress, endoplasmic reticulum stress, and streptozotocin- and cytokine-induced stress and preserves beta cell viability and insulin secretion. In skeletal muscle, DJ-1 controls energy metabolism and efficient fuel utilization, whereas in adipose tissue a role in adipogenesis and obesity-induced inflammation has been reported. This suggests that DJ-1 plays multiple roles in many cell types under metabolically challenging conditions as seen in obesity, insulin resistance, and T2DM.

Mitochondrial control of cell bioenergetics in Parkinson's disease

Parkinson disease (PD) is a neurodegenerative disorder characterized by a selective loss of dopaminergic neurons in the substantia nigra. The earliest biochemical signs of the disease involve failure in mitochondrial-endoplasmic reticulum cross talk and lysosomal function, mitochondrial electron chain impairment, mitochondrial dynamics alterations, and calcium and iron homeostasis abnormalities. These changes are associated with increased mitochondrial reactive oxygen species (mROS) and energy deficiency. Recently, it has been reported that, as an attempt to compensate for the mitochondrial dysfunction, neurons invoke glycolysis as a low-efficient mode of energy production in models of PD. Here, we review how mitochondria orchestrate the maintenance of cellular energetic status in PD, with special focus on the switch from oxidative phosphorylation to glycolysis, as well as the implication of endoplasmic reticulum and lysosomes in the control of bioenergetics.

Dose-related antihyperglycemic and hypolipidemic effects of two novel thiazolidin-4-ones in a rodent model of metabolic syndrome

BACKGROUND

The replacement of the thiazolidinedione moiety with a thiazolidinone may yield antidiabetic compounds with similar pleiotropic effects. Hence, the aim of the present study was to explore the dose-related antihyperglycemic and hypolipidemic effects of two synthesized novel thiazolidin-4-one derivatives, one with a nicotinamide and the other with a p-chlorophenoxyacetamide substitution at the N3 position of the thiazolidinone ring (NAT1 and PAT1, respectively), in a rodent model of metabolic syndrome (MetS).

METHODS

Metabolic syndrome was induced in Wistar rats by neonatal administration of monosodium glutamate (i.p.) on 4 consecutive days followed by high-sucrose diet feeding for 6 months. The effects of NAT1 (33 and 66 mg/kg) and molar equivalent doses of PAT1 (40 and 80 mg/kg) on relevant biochemical parameters were evaluated. Because MetS is a state of chronic low-grade inflammation, we also evaluated the effects of these compounds on proinflammatory markers, namely interleukin (IL)-6, tumor necrosis factor (TNF)-α, reactive oxygen species (ROS), and nitric oxide (NO).

RESULTS

Both NAT1 and PAT1 attenuated hyperglycemia, hypertriglyceridemia, hypoalphalipoproteinemia, and glucose intolerance. PAT1 exhibited superior antihyperglycemic and antihypoalphalipoproteinemic effects than NAT1. However, NAT1 had a better triglyceride-lowering effect. At the lower dose tested, both compounds significantly reduced elevated malondialdehyde levels. In addition, PAT1 (80 mg/kg) restored hepatic superoxide dismutase enzyme levels. There was a tendency for NAT1 and PAT1 to inhibit elevated hepatic IL-6 and TNF-α levels, but the differences did not reach statistical significance. In addition, PAT1 exhibited in vitro anti-inflammatory activity by reducing proinflammatory ROS and NO levels in RAW264.7 macrophages.

CONCLUSIONS

The novel thiazolidin-4-ones NAT1 and PAT1 could be potential pleiotropic drug candidates targeting MetS.

Tat-DJ-1 inhibits oxidative stress-mediated RINm5F cell death through suppression of NF-κB and MAPK activation

Oxidative stress is highly involved in the development of diabetes mellitus by destruction of pancreatic β-cells. DJ-1 is an antioxidant protein and DJ-1 expression levels are known to be reduced in diabetes mellitus. Thus, we examined the effects of DJ-1 protein against oxidative stress-induced pancreatic β-cell (RINm5F) death using cell permeable wild-type and mutant-type (C106A) Tat-DJ-1 proteins, which both efficiently transduced into RINm5F cells. Intracellular stability of wild-type Tat-DJ-1 persisted two times longer than C106A Tat-DJ-1. Wild-type Tat-DJ-1 protein markedly protected cells from hydrogen peroxide-induced toxicities such as cell death, reactive oxygen species generation, and DNA fragmentation. Further, wild-type Tat-DJ-1 protein significantly inhibited hydrogen peroxide-induced activation of mitogen-activated protein kinases and NF-κB signaling. On the other hand, C106A Tat-DJ-1 protein did not show the same protective effects. These results indicate that wild-type Tat-DJ-1 inhibits oxidative stress-induced cellular toxicity and activation of mitogen-activated protein kinases and NF-κB signals in RINm5F cells. These results suggest that wild-type Tat-DJ-1 protein may be a potential therapeutic agent against diabetes mellitus or toward the prevention of pancreatic β-cell destruction.

The Parkinsonism-associated protein DJ-1/Park7 prevents glycation damage in human keratinocyte

Reducing sugars and dicarbonyls form covalent adducts with proteins through a nonenzymatic process known as glycation, which inactivates proteins, is increased in diabetic patients and is associated with diabetic complications, including retinopathy, cataracts, nephropathy, neuropathy, cardiomyopathy and skin defects. We recently characterized DJ-1/Park7 as a protein deglycase that repairs proteins from glycation by glyoxal and methylglyoxal, two major glycating agents which are responsible for up to 65% of glycation events. In this study, we investigated the ability of DJ-1 to prevent protein glycation in keratinocytes. Glycation of collagen and keratinocyte proteins was tested by measuring ultraviolet absorption and fluorescence emission. Protein glycation in HaCaT keratinocytes was investigated by immunodetection with anti-advanced glycation endproduct antibodies, after DJ-1 depletion or overexpression. In vitro, DJ-1 prevented glycation of collagen and keratinocyte protein extracts. In cell culture, DJ-1 depletion by small interfering RNAs resulted in a 3-fold increase in protein glycation levels. Moreover, protein glycation levels were decreased several-fold in cells overexpressing DJ-1 after addition of the Nrf2 inducer sulforaphane or after transfection with a DJ-1 plasmid. Thus, the DJ-1 deglycase plays a major role in preventing protein glycation in eukaryotic cells and might be important for preventing skin glycation.

Myofibrillogenesis regulator-1 attenuated hypoxia/reoxygenation-induced apoptosis by inhibiting the PERK/Nrf2 pathway in neonatal rat cardiomyocytes

The purpose of this study was to investigate the role of myofibrillogenesis regulator-1 (MR-1) in cardiomyocyte apoptosis induced by hypoxia/reoxygenation (H/R), through protein kinase R-like ER kinase (PERK)/nuclear factor erythroid 2-related factor 2 (Nrf2) pathway. To address this aim, an H/R model of neonatal rat cardiomyocytes was used. MR-1 was overexpressed using an adenoviral vector system and knocked down using MR-1 specific siRNA. Apoptosis was assessed by using Annexin V/PI double staining, terminal deoxynucleotidyl transferase mediated dUTP-biotin nick end labeling assay, and the Bcl-2/Bax ratio. Western blotting was used to detect the protein levels of MR-1, glucose-regulated protein 78 (GRP78), total and phosphorylated PERK, Nrf2, activating transcription factor 4 (ATF4), C/EBP homologous protein (CHOP), Bcl-2 and Bax. Immunofluorescence staining was used to assess the subcellular location of Nrf2. We found that H/R induced significant apoptosis in neonatal rat cardiomyocytes. MR-1 overexpression attenuated H/R-induced apoptosis, decreased GRP78 (P < 0.01) and CHOP expression (P < 0.05), and increased the Bcl-2/Bax ratio (P < 0.01). MR-1 overexpression suppressed H/R-induced PERK phosphorylation, Nrf2 nuclear translocation, and ATF4 expression (P < 0.01). While MR-1 knockdown aggravated H/R-induced apoptosis, increased expression of GRP78 and CHOP (P < 0.05), and decreased the Bcl-2/Bax ratio (P < 0.01). MR-1 knockdown significantly increased H/R-induced PERK phosphorylation (P < 0.05), Nrf2 nuclear translocation, and ATF4 expression (P < 0.01). These findings suggest that MR-1 alleviates H/R-induced cardiomyocyte apoptosis through inhibition of the PERK/Nrf2 pathway.

Keap1-Nrf2 regulated redox signaling in utero: Priming of disease susceptibility in offspring

Intrauterine exposure to gestational diabetes, pre-eclampsia or intrauterine growth restriction alters the redox status of the developing fetus. Such pregnancy-related diseases in most cases do not have a readily identifiable genetic cause, and epigenetic 'priming' mechanisms in utero may predispose both mother and child to later-life onset of cardiovascular and metabolic diseases. The concept of 'fetal programing' or 'developmental priming' and its association with an increased risk of disease in childhood or adulthood has been reviewed extensively. This review focuses on adaptive changes in the in utero redox environment during normal pregnancy and the consequences of alterations in redox control associated with pregnancies characterized by oxidative stress. We evaluate the evidence that the Keap1-Nrf2 pathway is important for protecting the fetus against adverse conditions in utero and may itself be subject to epigenetic priming, potentially contributing to an increased risk of vascular disease and insulin resistance in later life.

DJ-1 Protects Pancreatic Beta Cells from Cytokine- and Streptozotocin-Mediated Cell Death

A hallmark feature of type 1 and type 2 diabetes mellitus is the progressive dysfunction and loss of insulin-producing pancreatic beta cells, and inflammatory cytokines are known to trigger beta cell death. Here we asked whether the anti-oxidant protein DJ-1 encoded by the Parkinson’s disease gene PARK7 protects islet cells from cytokine- and streptozotocin-mediated cell death. Wild type and DJ-1 knockout mice (KO) were treated with multiple low doses of streptozotocin (MLDS) to induce inflammatory beta cell stress and cell death. Subsequently, glucose tolerance tests were performed, and plasma insulin as well as fasting and random blood glucose concentrations were monitored. Mitochondrial morphology and number of insulin granules were quantified in beta cells. Moreover, islet cell damage was determined in vitro after streptozotocin and cytokine treatment of isolated wild type and DJ-1 KO islets using calcein AM/ethidium homodimer-1 staining and TUNEL staining. Compared to wild type mice, DJ-1 KO mice became diabetic following MLDS treatment. Insulin concentrations were substantially reduced, and fasting blood glucose concentrations were significantly higher in MLDS-treated DJ-1 KO mice compared to equally treated wild type mice. Rates of beta cell apoptosis upon MLDS treatment were twofold higher in DJ-1 KO mice compared to wild type mice, and in vitro inflammatory cytokines led to twice as much beta cell death in pancreatic islets from DJ-1 KO mice versus those of wild type mice. In conclusion, this study identified the anti-oxidant protein DJ-1 as being capable of protecting pancreatic islet cells from cell death induced by an inflammatory and cytotoxic setting.

Dysregulation of redox-state-regulating enzymes in melanocytic skin tumours and the surrounding microenvironment

AIMS

To investigate redox-regulating enzymes that may have a special role in melanoma pathogenesis due to continuous exposure to microenvironment-produced and ultraviolet radiation-induced oxidative stress.

METHODS AND RESULTS

We assessed immunohistochemically the expression of antioxidant enzymes peroxiredoxins (Prxs) I-IV, sulfiredoxin (Srx) and redox-regulated proto-oncogene DJ-1 in material consisting of 30 benign naevi, 14 lentigo malignas and 67 malignant melanomas. Evaluation of immunostaining was performed with special attention paid to protein expression in different tumour compartments. In particular, the expression patterns of nuclear Prx I and Prx II and cytoplasmic DJ-1 were decreased significantly in melanomas compared with dysplastic and benign naevi. In multivariate analysis, several prognostic factors were identified: Prx III expression in the cytoplasm of stromal fibroblasts was associated with shortened melanoma-specific survival [hazard ratio (HR) 6.730; 95% confidence interval (CI) 1.579-28.689], while cytoplasmic Prx IV expression in endothelial cells (HR 6.563; 95% CI 1.750-24.620) and Srx expression in the cytoplasm of keratinocytes (HR 6.988; 95% CI 1.559-31.324) were associated with better prognosis independently of ulceration, thickness of melanoma or its diagnostic type.

CONCLUSIONS

Redox-regulating enzymes have the potential to serve as novel prognostic factors and targeting them may offer new therapeutic options in malignant melanoma.

Preoperative serum 8-hydroxydeoxyguanosine is associated with chemoresistance and is a powerful prognostic factor in endometrioid-type epithelial ovarian cancer

Background

Oxidative stress is a widely seen phenomenon in several carcinomas. Increasing evidence also suggests that it has a significant role in the development of epithelial ovarian carcinoma (EOC). 8-Hydroxydeoxyguanosine (8-OHdG) is one of the main indicators of oxidative stress and increased expression of 8-OHdG has previously been seen in EOC. DJ-1 is an oncoprotein connected to oxidative stress regulation, but its role in ovarian cancer is not well known. We investigated redox status in different histotypes of EOC by measuring serum 8-OHdG and DJ-1 concentrations and their associations with known prognostic factors.

Methods

Serum samples from newly diagnosed EOC patients were collected in 1996–2009 and stored at the Department of Obstetrics and Gynecology, Oulu University Hospital. Serum 8-OHdG and DJ-1 levels were measured by using commercially available ELISA kits. Clinical data was gathered retrospectively from the patients` files. Results were analyzed by using SPSS software.

Results

In total, 112 patient samples were analyzed (38 serous, 20 mucinous, 34 endometrioid and 20 clear-cell). High serum 8-OHdG levels were associated with poor overall survival (OS) (p = 0.019), poor disease-free survival (DFS) (p = 0.020), platinum resistance (p = 0.002), serous histology versus other (p = 0.033), stage III–IV versus I–II (p = 0.009) and suboptimal surgical outcome (p = 0.012). Regarding histotypes, in the endometrioid EOC group in particular, serum 8-OHdG levels were significantly associated with poor DFS (p = 0.005), suboptimal surgical outcome (p = 0.025), and platinum resistance (p = 0.007). The prognostic significance of 8-OHdG in patients with endometrioid cancer in terms of DFS was confirmed in Cox regression analysis. High DJ-1 levels were associated with high histological grade (p = 0.029) and nonsignificantly associated with serous histology vs. other histology (p = 0.089).

Conclusions

An elevated serum 8-OHdG level is a significant predictor of poor prognosis, especially in cases of the endometrioid subtype of ovarian carcinoma. High 8-OHdG levels are associated with all traditional factors of poor prognosis in ovarian cancer and they also predict earlier development of platinum resistance. These results could be valuable when deciding the primary treatment mode for EOC patients.

DJ-1 links muscle ROS production with metabolic reprogramming and systemic energy homeostasis in mice

Reactive oxygen species (ROS) have been linked to a wide variety of pathologies, including obesity and diabetes, but ROS also act as endogenous signalling molecules, regulating numerous biological processes. DJ-1 is one of the most evolutionarily conserved proteins across species, and mutations in DJ-1 have been linked to some cases of Parkinson's disease. Here we show that DJ-1 maintains cellular metabolic homeostasis via modulating ROS levels in murine skeletal muscles, revealing a role of DJ-1 in maintaining efficient fuel utilization. We demonstrate that, in the absence of DJ-1, ROS uncouple mitochondrial respiration and activate AMP-activated protein kinase, which triggers Warburg-like metabolic reprogramming in muscle cells. Accordingly, DJ-1 knockout mice exhibit higher energy expenditure and are protected from obesity, insulin resistance and diabetes in the setting of fuel surplus. Our data suggest that promoting mitochondrial uncoupling may be a potential strategy for the treatment of obesity-associated metabolic disorders.

The protein DJ-1 is known to have antioxidant effects in cells. Here, the authors reveal that DJ-1 has a role in coupling mitochondrial respiration in skeletal muscles of mice, and show that absence of DJ-1 increases energy expenditure and protects mice from diet-induced obesity.

Gender-dimorphic regulation of DJ1 and its interactions with metabolic proteins in streptozotocin-induced diabetic rats

Regulation of DJ1 is associated with a number of human diseases. To determine the involvement of DJ1 in progression of diabetes in a gender-dependent manner, we investigated its tissue-specific expression in streptozotocin (STZ)-induced diabetic male and female rats in this study. In animal experiments, females showed greater susceptibility towards developing diabetes because of lower insulin secretion and higher blood glucose levels as compared to male diabetic rats upon exposure to STZ. Immunoblotting confirmed sexually dimorphic regulation of DJ1 in various metabolic tissues such as the liver, pancreas and skeletal muscle. Immunofluorescence analysis revealed the location as well as reinforced the gender-dependent expression of DJ1 in hepatic tissue. Co-immunoprecipitation assay identified several interacting proteins with DJ1 whose functions were shown to be involved in various metabolic pathways viz. antioxidative and stress defence system, protein and methionine metabolism, nitrogen metabolism, urea metabolism, etc. Using GeneMANIA, a predictive web interface for gene functions, we showed for the first time that DJ1 may regulate T1DM via the JNK1 pathway, suggesting DJ1 interacts with other proteins from various metabolic pathways. We anticipate that the current data will provide insights into the aetiology of T1DM.

DJ-1 as a human oncogene and potential therapeutic target

DJ-1 is a cancer- and Parkinson's disease-associated protein that participates in different intracellular signaling pathways to protect cells from toxic stresses. DJ-1 expression, oxidation, localization, and phosphorylation are often altered in human tumors, and DJ-1 has been implicated in various aspects of transformation, including uncontrolled proliferation, invasion, metastasis, and resistance to chemotherapy and apoptosis. Despite the strong relationship between DJ-1 and cancer, which made it a particularly attractive therapeutic target for cancer treatment, the detailed mechanisms of how this oncogene coordinates altered signaling with cell survival remains elusive. In this commentary, we discuss the role of DJ-1 in transformation, highlight some of the significant aspects of and prospects for therapeutically targeting the DJ-1 signaling in cancer, and describe what the future may hold.

Serum DJ-1 level is positively associated with improvements in some aspects of metabolic syndrome in Japanese women through lifestyle intervention

DJ-1 is a protein that is associated with Parkinson disease and cancer, and the reduction of DJ-1 function and expression is also thought to be a cause of diabetes and hypertension. However, little is known about the association between the plasma concentration of DJ-1 and risk of metabolic syndrome. We hypothesized that a lifestyle intervention would increase serum DJ-1 and that up-regulated DJ-1 functions will result in the prevention of metabolic syndrome. The objective of our study is to examine whether the level of serum DJ-1 is associated with the risk of metabolic syndrome. Therefore, to reveal the association between DJ-1 and metabolic syndrome, this study investigated lifestyle intervention in a control group (n = 37) and intervention group (n = 45). The results showed that body mass index, body fat ratio, waist-hip ratio, waist circumference, blood pressure, and plasma glucose level were improved in the intervention group, as compared with those in the control group. Furthermore, serum levels of DJ-1 were increased in the intervention group, when compared with those in the control group. These results suggest that serum DJ-1 is increased by lifestyle intervention and that increased serum DJ-1 prevents metabolic syndrome. Thus, the level of serum DJ-1 will become one of the indexes for the risk of metabolic syndrome.

DJ-1 contributes to adipogenesis and obesity-induced inflammation

Adipose tissue functions as an endocrine organ, and the development of systemic inflammation in adipose tissue is closely associated with metabolic diseases, such as obesity and insulin resistance. Accordingly, the fine regulation of the inflammatory response caused by obesity has therapeutic potential for the treatment of metabolic syndrome. In this study, we analyzed the role of DJ-1 (PARK7) in adipogenesis and inflammation related to obesity in vitro and in vivo. Many intracellular functions of DJ-1, including oxidative stress regulation, are known. However, the possibility of DJ-1 involvement in metabolic disease is largely unknown. Our results suggest that DJ-1 deficiency results in reduced adipogenesis and the down-regulation of pro-inflammatory cytokines in vitro. Furthermore, DJ-1-deficient mice show a low-level inflammatory response in the high-fat diet-induced obesity model. These results indicate previously unknown functions of DJ-1 in metabolism and therefore suggest that precise regulation of DJ-1 in adipose tissue might have a therapeutic advantage for metabolic disease treatment.

DJ-1 upregulates breast cancer cell invasion by repressing KLF17 expression

BACKGROUND

DJ-1 (PARK7) was reported as an oncogene in a Ras-dependent manner. Recent studies have shown that DJ-1 stimulates cell proliferation, cell invasion, and cancer metastasis. However, the molecular mehchanism by which DJ-1 induces cancer cell invasion and metastasis remains unclear.

METHODS

Breast cancer cells were transfected with DJ-1 siRNA or DJ-1 overexpression to investigate the effect of DJ-1 on KLF17 expression. ID-1 luciferase promoter assay was performed to evaluate DJ-1-dependent KLF17 expression changes. In addition, Epistasis analysis of DJ-1 and KLF17 was performed to evaluate their regulatory interactions. Ras inhibitors were pretreated to determine whether DJ-1 regulates cell invasion in a Ras-dependent manner.

RESULTS

I n the present study, we found increased DJ-1 expression in highly invasive breast cancer cells as compared with non-metastatic cells. Furthermore, DJ-1 promoted breast cancer cell invasion by downregulating E-cadherin and increasing Snail expression. Interestingly, exogenous DJ-1 overexpression markedly decreased mRNA and protein expression of KLF17, the EMT negative regulator. These data were confirmed by ID-1 promoter activity, which is directly regulated by DJ-1-dependent KLF17 transcription factor. Epistasis analysis showed that KLF17 overexpression overcomes increased cell invasion by DJ-1, suggesting that KLF17 might be one of the downstream signalling molecules of DJ-1. Acceleration of cell invasion by DJ-1 was alleviated by Ras inhibitors, suggesting that DJ-1 cooperates with Ras to increase cell invasion.

CONCLUSION

Altogether, these data suggest for the first time that DJ-1 acts as an EMT-positive regulator in breast cancer cells via regulation of the KLF17/ID-1 pathway.

Renal dopamine receptors, oxidative stress, and hypertension

Dopamine, which is synthesized in the kidney, independent of renal nerves, plays an important role in the regulation of fluid and electrolyte balance and systemic blood pressure. Lack of any of the five dopamine receptor subtypes (D1R, D2R, D3R, D4R, and D5R) results in hypertension. D1R, D2R, and D5R have been reported to be important in the maintenance of a normal redox balance. In the kidney, the antioxidant effects of these receptors are caused by direct and indirect inhibition of pro-oxidant enzymes, specifically, nicotinamide adenine dinucleotide phosphate, reduced form (NADPH) oxidase, and stimulation of anti-oxidant enzymes, which can also indirectly inhibit NADPH oxidase activity. Thus, stimulation of the D2R increases the expression of endogenous anti-oxidants, such as Parkinson protein 7 (PARK7 or DJ-1), paraoxonase 2 (PON2), and heme oxygenase 2 (HO-2), all of which can inhibit NADPH oxidase activity. The D5R decreases NADPH oxidase activity, via the inhibition of phospholipase D2, and increases the expression of HO-1, another antioxidant. D1R inhibits NADPH oxidase activity via protein kinase A and protein kinase C cross-talk. In this review, we provide an overview of the protective roles of a specific dopamine receptor subtype on renal oxidative stress, the different mechanisms involved in this effect, and the role of oxidative stress and impairment of dopamine receptor function in the hypertension that arises from the genetic ablation of a specific dopamine receptor gene in mice.

Expression of PARK7 is increased in celiac disease

Recently, it has been suggested that the gene called Parkinson's disease 7 (PARK7) might be an upstream activator of hypoxia-inducible factor (HIF)-1α, which plays a major role in sustaining intestinal barrier integrity. Furthermore, PARK7 has been proposed to participate in the Toll-like receptor (TLR)-dependent regulation of the innate immune system. Our aim was to investigate the involvement of PARK7 in the pathogenesis of coeliac disease (CD). Duodenal biopsy specimens were collected from 19 children with untreated CD, five children with treated CD (maintained on gluten-free diet), and ten children with histologically normal duodenal biopsies. PARK7 mRNA expression and protein level were determined by real-time polymerase chain reaction (PCR) and Western blot, respectively. Localization of PARK7 was visualized by immunofluorescence staining. Protein level of PARK7 increased in the duodenal mucosa of children with untreated CD compared to children with treated CD or to control biopsies (p <0.03). We detected intensive PARK7 staining in the epithelial cells and lamina propria of the duodenal mucosa of children with untreated CD compared with that in control biopsies. Our finding that mucosal expression of PARK7 is increased suggests that PARK7 is involved in the pathogenesis of gastrointestinal diseases, notably CD. Our results suggest that PARK7 may alter processes mediated by HIF-1α and TLR4, which supports a role for PARK7 in the maintenance of epithelial barrier integrity, immune homeostasis, or apoptosis.

DJ-1-dependent regulation of oxidative stress in the retinal pigment epithelium (RPE)

BACKGROUND

DJ-1 is found in many tissues, including the brain, where it has been extensively studied due to its association with Parkinson's disease. DJ-1 functions as a redox-sensitive molecular chaperone and transcription regulator that robustly protects cells from oxidative stress.

METHODOLOGY

Retinal pigment epithelial (RPE) cultures were treated with H2O2 for various times followed by biochemical and immunohistological analysis. Cells were transfected with adenoviruses carrying the full-length human DJ-1 cDNA and a mutant construct, which has the cysteine residues at amino acid 46, 53 and 106 mutated to serine (C to S) prior to stress experiments. DJ-1 localization, levels of expression and reactive oxygen species (ROS) generation were also analyzed in cells expressing exogenous DJ-1 under baseline and oxidative stress conditions. The presence of DJ-1 and oxidized DJ-1 was evaluated in human RPE total lysates. The distribution of DJ-1 was assessed in AMD and non-AMD cryosectionss and in isolated human Bruch's membrane (BM)/choroid from AMD eyes.

PRINCIPAL FINDINGS

DJ-1 in RPE cells under baseline conditions, displays a diffuse cytoplasmic and nuclear staining. After oxidative challenge, more DJ-1 was associated with mitochondria. Increasing concentrations of H2O2 resulted in a dose-dependent increase in DJ-1. Overexpression of DJ-1 but not the C to S mutant prior to exposure to oxidative stress led to significant decrease in the generation of ROS. DJ-1 and oxDJ-1 intensity of immunoreactivity was significantly higher in the RPE lysates from AMD eyes. More DJ-1 was localized to RPE cells from AMD donors with geographic atrophy and DJ-1 was also present in isolated human BM/choroid from AMD eyes.

CONCLUSIONS/SIGNIFICANCE

DJ-1 regulates RPE responses to oxidative stress. Most importantly, increased DJ-1 expression prior to oxidative stress leads to decreased generation of ROS, which will be relevant for future studies of AMD since oxidative stress is a known factor affecting this disease.

Evolution of general transcription factors

Three genes GTF2IRD1, GTF2I, and GTF2IRD2, which encode members of the GTF2I (or TFII-I) family of so-called general transcription factors, were discovered and studied during the last two decades. Chromosome location and similarity of exon-intron structures suggest that the family evolved by duplications. The initial duplication of ancestral proto-GTF2IRD1 gene likely occurred in early vertebrates prior to origin of cartilaginous fish and led to formation of GTF2I (>450 MYA), which was later lost in bony fish but successfully evolved in the land vertebrates. The second duplication event, which created GTF2IRD2, occurred prior to major radiation events of eutherian mammalian evolution (>100 MYA). During recent steps of primate evolution there was another duplication which led to formation of GTF2IRD2B (<4 MYA). Two latest duplications were coupled with inversions. Genes belonging to the family have several highly conservative repeats which are implicated in DNA binding. Phylogenetic analysis of the repeats revealed a pattern of intragenic duplications, deletions and substitutions which led to diversification of the genes and proteins. Distribution of statistically rare atypical substitutions (p ≤ 0.01) sheds some light on structural differentiation of repeats and hence evolution of the genes. The atypical substitutions are often located on secondary structures joining α-helices and affect 3D arrangement of the protein globule. Such substitutions are commonly traced at the early stages of evolution in Tetrapoda, Amniota, and Mammalia.

2'-Benzoyloxycinnamaldehyde-mediated DJ-1 upregulation protects MCF-7 cells from mitochondrial damage

2'-Benzoyloxycinnamaldehyde (BCA) is a promising antitumor agent which induces cancer cells apoptosis via reactive oxygen species (ROS) generation. BCA shows more effective antiproliferation in MDA-MB-435 than in MCF-7 breast cancer cells. DJ-1 has been known to protect cells against oxidative stress as an antioxidant because of its cysteine residues sensitive to oxidative stress. In the present study, we evaluated the mechanism of DJ-1 for cell protection from oxidative stress after BCA treatment in MCF-7 cell. BCA upregulates the expression of DJ-1 in MCF-7 cells. However, DJ-1 expression decreased continuously for 24 h after BCA treatment in MDA-MB-435 cells. DJ-1 knockdown sensitized MCF-7 cells to BCA, on the contrary, DJ-1 overexpression induced MDA-MB-435 cells less sensitive to BCA. Confocal microscopic observation showed that only in MCF-7 cells BCA increased the overlapped signal between mitochondria and DJ-1 protein. Mitochondrial membrane potential (MMP) was decreased in MDA-MB-435 cells by BCA, and DJ-1 overexpression inhibited BCA-induced MMP decrease in these cells. On the contrary, DJ-1 knockdown in MCF-7 induced MMP perturbation by BCA. These findings suggest that DJ-1 upregulation protects MCF-7 cells from BCA via inhibiting mitochondrial damage.

Comparative secretome analyses using a hollow fiber culture system with label-free quantitative proteomics indicates the influence of PARK7 on cell proliferation and migration/invasion in lung adenocarcinoma

As the leading cause of cancer death worldwide, lung cancer lacks effective diagnosis tools and treatments to prevent its metastasis. Fortunately, secretome has clinical usages as biomarkers and protein drugs. To discover the secretome that influences lung adenocarcinoma metastasis, the hollow fiber culture (HFC) system was used along with label-free proteomics approach to analyze cell secretomes between CL1-0 and CL1-5 cell lines, which exhibit low and high metastatic potentials. Among the 703 proteins quantified, 50 possessed different levels between CL1-0 and CL1-5. PARK7 was a primary focus because of the lack of research involving lung adenocarcinoma. The cell proliferation, migration, and invasion properties of CL1-0, CL1-5, and A549 cells were significantly diminished when the expression of their PARK7 proteins was reduced. Conversely, these functions were promoted when PARK7 was overexpressed in CL1-0. In clinical expression, PARK7 levels within tissue specimens and plasma samples were significantly higher in the cancer group. This represents the first time the HFC system has been used with label-free quantification to discern the elements of metastasis in lung adenocarcinoma cell secretomes. Likewise, PARK7 has never been researched for its role in promoting lung adenocarcinoma progression.

Age- and diet-dependent requirement of DJ-1 for glucose homeostasis in mice with implications for human type 2 diabetes

Elderly patients often suffer from multiple age-related diseases. Here we show that the expression of DJ-1, an antioxidant protein with reduced expression in the central nervous system of patients with Parkinson's disease, is reduced in pancreatic islets of patients with type 2 diabetes mellitus (T2DM). In contrast, under non-diabetic conditions, DJ-1 expression increases in mouse and human islets during aging. In mouse islets, we show that DJ-1 prevents an increase in reactive oxygen species levels as the mice age. This antioxidant function preserves mitochondrial integrity and physiology, prerequisites for glucose-stimulated insulin secretion. Accordingly, DJ-1-deficient mice develop glucose intolerance and reduced β cell area as they age or gain weight. Our data suggest that DJ-1 is more generally involved in age- and lifestyle-related human diseases and show for the first time that DJ-1 plays a key role in glucose homeostasis and might serve as a novel drug target for T2DM.

Inflammation-Mediated Regulation of MicroRNA Expression in Transplanted Pancreatic Islets

Nonspecific inflammation in the transplant microenvironment results in β-cell dysfunction and death influencing negatively graft outcome. MicroRNA (miRNA) expression and gene target regulation in transplanted islets are not yet well characterized. We evaluated the impact of inflammation on miRNA expression in transplanted rat islets. Islets exposed in vitro to proinflammatory cytokines and explanted syngeneic islet grafts were evaluated by miRNA arrays. A subset of 26 islet miRNAs was affected by inflammation both in vivo and in vitro. Induction of miRNAs was dependent on NF-κB, a pathway linked with cytokine-mediated islet cell death. RT-PCR confirmed expression of 8 miRNAs. The association between these miRNAs and mRNA target-predicting algorithms in genome-wide RNA studies of β-cell inflammation identified 238 potential miRNA gene targets. Several genes were ontologically associated with regulation of insulin signaling and secretion, diabetes, and islet physiology. One of the most activated miRNAs was miR-21. Overexpression of miR-21 in insulin-secreting MIN6 cells downregulated endogenous expression of the tumor suppressor Pdcd4 and of Pclo, a Ca²⁺ sensor protein involved in insulin secretion. Bioinformatics identified both as potential targets. The integrated analysis of miRNA and mRNA expression profiles revealed potential targets that may identify molecular targets for therapeutic interventions.

15-Deoxy-Δ12,14-prostaglandin J₂ modulates manganese-induced activation of the NF-κB, Nrf2, and PI3K pathways in astrocytes

Excessive exposure to manganese (Mn) increases levels of oxidative stressors and proinflammatory mediators, such as cyclooxygenase-2 and prostaglandin E(2). Mn also activates nuclear factor-κB (NF-κB), an important mediator of inflammation. The signaling molecule 15-deoxy-Δ12,14-prostaglandin J(2) (15 d-PGJ(2)) is an anti-inflammatory prostaglandin. Here, we tested the hypothesis that 15 d-PGJ(2) modulates Mn-induced activation of astrocytic intracellular signaling, including NF-κB and nuclear factor erythroid 2-related factor (Nrf2), a master regulator of antioxidant transcriptional responses. The results establish that 15 d-PGJ(2) suppresses Mn-induced NF-κB activation by interacting with several signaling pathways. The PI3K/Akt pathway, which is upstream of NF-κB, plays a role in this activation, because (i) pretreatment with 15 d-PGJ(2) (10 μM for 1h) significantly (p<0.01) inhibited Mn (500 μM)-induced PI3K/Akt activation and (ii) inhibition of the PI3K/Akt pathway with LY29004 significantly (p<0.05) decreased NF-κB activation. 15 d-PGJ(2) also significantly (p<0.05) attenuated Mn-induced astrocytic NF-κB activation by inhibiting the Mn-induced phosphorylation of IκB kinase and subsequent IκB-α degradation. Because Mn-induced oxidative stress is also associated with Nrf2 activation, additional studies addressed the ability of 15 d-PGJ(2) to modulate the Nrf2 pathway. 15 d-PGJ(2) significantly (p<0.01) increased Nrf2 expression in whole-cell lysates. Consistent with its pro-oxidant properties, Mn also increased Nrf2 expression. Nevertheless, cotreatment of whole-cell lysates with both Mn and 15 d-PGJ(2) partially suppressed (p<0.01) the 15 d-PGJ(2)-induced increase in astrocytic Nrf2 protein expression. Mn treatment also decreased (p<0.001) expression of DJ-1, a Parkinson disease-associated protein and a stabilizer of Nrf2, and 15 d-PGJ(2) attenuated Mn-induced astrocytic inhibition of DJ-1 expression. Collectively, these results demonstrate that 15d-PGJ(2) exerts a protective effect in astrocytes against Mn-induced inflammation and oxidative stress by modulating the activation of the NF-κB and Nrf2 signaling pathways.

Biochemistry and biology of the inducible multifunctional transcription factor TFII-I: 10 years later

Exactly twenty years ago TFII-I was discovered as a biochemical entity that was able to bind to and function via a core promoter element called the Initiator (Inr). Since then several different properties of this signal-induced multifunctional factor were discovered. Here I update these ever expanding functions of TFII-I--focusing primarily on the last ten years since the first review appeared in this journal.

Potential role of intravitreal human placental stem cell implants in inhibiting progression of diabetic retinopathy in type 2 diabetes: neuroprotective growth factors in the vitreous

Background:

Intravitreal injection of human mesenchymal stem cells has been shown to be effective in slowing the progression of diabetic retinopathy in an animal model of chemically induced diabetes mellitus. We studied changes in growth factor levels released from human mesenchymal stem cells in the vitreous cavity as well as changes in growth factor levels in host retinal neurons following intravitreal injection.

Methods:

Twenty-two Lewis rats were treated with an intravitreal human mesenchymal stem cell microinjection. Determination of neurotrophic factors released by human mesenchymal stem cells in the vitreous was carried out using real-time polymerase chain reaction.

Results:

Detectable levels of neurotrophic factors were identified postoperatively in the vitreous of all rats.

Conclusion:

Increased intravitreal and retinal concentrations of neuroprotective growth factors in rats confirm the neuroprotective activity of human mesenchymal stem cells in diabetic retinopathy.

Molecular basis for vulnerability to mitochondrial and oxidative stress in a neuroendocrine CRI-G1 cell line

Background

Many age-associated disorders (including diabetes, cancer, and neurodegenerative diseases) are linked to mitochondrial dysfunction, which leads to impaired cellular bioenergetics and increased oxidative stress. However, it is not known what genetic and molecular pathways underlie differential vulnerability to mitochondrial dysfunction observed among different cell types.

Methodology/Principal Findings

Starting with an insulinoma cell line as a model for a neuronal/endocrine cell type, we isolated a novel subclonal line (named CRI-G1-RS) that was more susceptible to cell death induced by mitochondrial respiratory chain inhibitors than the parental CRI-G1 line (renamed CRI-G1-RR for clarity). Compared to parental RR cells, RS cells were also more vulnerable to direct oxidative stress, but equally vulnerable to mitochondrial uncoupling and less vulnerable to protein kinase inhibition-induced apoptosis. Thus, differential vulnerability to mitochondrial toxins between these two cell types likely reflects differences in their ability to handle metabolically generated reactive oxygen species rather than differences in ATP production/utilization or in downstream apoptotic machinery. Genome-wide gene expression analysis and follow-up biochemical studies revealed that, in this experimental system, increased vulnerability to mitochondrial and oxidative stress was associated with (1) inhibition of ARE/Nrf2/Keap1 antioxidant pathway; (2) decreased expression of antioxidant and phase I/II conjugation enzymes, most of which are Nrf2 transcriptional targets; (3) increased expression of molecular chaperones, many of which are also considered Nrf2 transcriptional targets; (4) increased expression of β cell-specific genes and transcription factors that specify/maintain β cell fate; and (5) reconstitution of glucose-stimulated insulin secretion.

Conclusions/Significance

The molecular profile presented here will enable identification of individual genes or gene clusters that shape vulnerability to mitochondrial dysfunction and thus represent potential therapeutic targets for diabetes and neurodegenerative diseases. In addition, the newly identified CRI-G1-RS cell line represents a new experimental model for investigating how endogenous antioxidants affect glucose sensing and insulin release by pancreatic β cells.