Nuclear Factor Erythroid-derived 2 Research Articles

ERK and p38 MAPK inhibition controls NF-E2 degradation and profibrotic signaling in renal proximal tubule cells

AimsTransforming growth factor-β (TGF-β) mediates fibrotic manifestations of diabetic nephropathy. We demonstrated proteasomal degradation of anti-fibrotic protein, nuclear factor-erythroid derived 2 (NF-E2), in TGF-β treated human renal proximal tubule (HK-11) cells and in diabetic mouse kidneys. The current study examined the role of mitogen-activated protein kinase (MAPK) pathways in mediating NF-E2 proteasomal degradation and stimulating profibrotic signaling in HK-11 cells. Main methodsHK-11 cells were pretreated with vehicle or appropriate proteasome and MAPK inhibitors, MG132 (0.5 μM), SB203580 (1 μM), PD98059 (25 μM) and SP600125 (10 μM), respectively, followed by treatment with/without TGF-β (10 ng/ml, 24 h). Cell lysates and kidney homogenates from FVB and OVE26 mice treated with/without MG132 were immunoblotted with appropriate antibodies. pUse vector and pUse-NF-E2 cDNA were transfected in HK-11 cells and effects of TGF-β on JNK MAPK phosphorylation (pJNK) was examined. Key findingsWe demonstrated activation of p38, ERK, and JNK MAPK pathways in TGF-β treated HK-11 cells. Dual p38 and ERK MAPK blockade prevented TGF-β-induced pSer82Hsp27, fibronectin and connective tissue growth factor (CTGF) expression while preserving NF-E2 expression. Blockade of JNK MAPK inhibited TGF-β-induced CTGF expression without preserving NF-E2 expression. MG132 treatment prevented TGF-β-induced pJNK in HK-11 cells and in type 1 diabetic OVE26 mouse kidneys, demonstrating that TGF-β- and diabetes-induced pJNK occurs downstream of proteasome activation. A direct role for NF-E2 in modulating pJNK activation was demonstrated by NF-E2 over-expression. SignificanceERK and p38 MAPK promotes NF-E2 proteasomal degradation while proteasome activation promotes pJNK and profibrotic signaling in renal proximal tubule cells.

Loss of NF-E2 expression contributes to the induction of profibrotic signaling in diabetic kidneys

AimsThis study aimed to examine the anti-fibrotic role of Nuclear Factor-Erythroid derived 2 (NF-E2) in human renal tubule (HK-11) cells and in type 1 and type 2 diabetic (T1D, T2D) mouse kidneys. Main methodsAnti-fibrotic effects of NF-E2 were examined in transforming growth factor-β (TGF-β) treated HK-11 cells by over-expressing/silencing NF-E2 expression and determining its effects on profibrotic signaling. NF-E2 proteasomal degradation was confirmed by proteasome inhibition in HK-11 cells and diabetic mice. Clinical relevance of changes in NF-E2 expression to fibrotic changes in the kidney were assessed in T1D and T2D mouse kidneys. Key findingsNF-E2 expression was significantly decreased in TGF-β treated HK-11 cells and in kidneys of diabetic mice with concurrent increase in expression of fibrotic proteins. TGF-β treatment of HK-11 cells did not inhibit NF-E2 mRNA expression, suggesting that the post-translational changes may contribute to NF-E2 protein degradation. The down-regulation of NF-E2 expression was attributed to its proteasomal degradation, as TGF-β- and diabetes-induced NF-E2 down regulation was prevented by proteasome inhibitor treatment. In HK-11 cells TGF-β treatment decreased E-cadherin expression and induced pSer82Hsp27/NF-E2 association, likely to promote NF-E2 degradation, as Hsp27 can target proteins to the proteasome. A critical role for NF-E2 in regulation of renal fibrosis was demonstrated as over-expression of NF-E2 or silencing NF-E2 expression, decreased or increased profibrotic proteins in TGF-β-treated HK-11 cells, respectively. SignificanceNF-E2, a novel anti-fibrotic protein, is down-regulated in diabetic kidneys. Preserving/inducing NF-E2 expression in diabetic kidneys may provide a therapeutic potential to combat DN.

Ganoderma Lucidum Polysaccharides Ameliorates Hepatic Steatosis and Oxidative Stress in db/db Mice via Targeting Nuclear Factor E2 (Erythroid-Derived 2)-Related Factor-2/Heme Oxygenase-1 (HO-1) Pathway.

BackgroundType 2 diabetes mellitus (T2DM) and its comorbidities, including obesity, hypertension, and hyperlipidemia, are commonly associated with non-alcoholic fatty liver disease (NAFLD). Ganoderma lucidum polysaccharide (GDLP) is one of the central bioactive components in Ganoderma lucidum with anti-inflammatory, antioxidant, and hepatoprotective properties. However, the effect and mechanisms of GDLP in hepatic steatosis remain largely unknown. In the present study, we aimed to investigate the function of GDLP in hepatic steatosis and the underlying mechanism.Material/MethodsIn this study, male db/db mice were received with a high-fat diet (HFD) to investigate the effect of GDLP in T2DM-induced hepatic steatosis. The biological characteristics of the hepatic steatosis were evaluated through the detection of clinical indicators, including biochemical parameters, histopathology, and related cytokine levels. Additionally, the protein expression levels of Nrf2 (nuclear factor E2 (erythroid-derived 2)-related factor-2) signaling pathway were investigated by using western blotting and immunohistochemical staining.ResultsThe levels of food/water intake, body weight, fasting blood glucose, plasma lipids, urinary biomarkers, hepatic lipid accumulation, and tumor necrosis factor (TNF)-α were observably decreased in GDLP-treated db/db mice. Additionally, administration of GDLP increased the expression of various antioxidases, including superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GSH-Px), whereas it reduced the level of malonaldehyde (MDA). Furthermore, GDLP was significantly promoted protein expression level of Nrf2 and its downstream target gene HO-1 (heme oxygenase-1) while decreased TNF-α expression.ConclusionsThese results indicate that GDLP against T2DM-induced hepatic steatosis, oxidative stress, and inflammation by improving the Nrf2/HO-1 signaling pathway in db/db mice, suggesting the GDLP may serve as an effective strategy for in fatty liver treatment.

Loss of NRF2 leads to impaired mitochondrial function, decreased synaptic density and exacerbated age-related cognitive deficits

Activation of the antioxidant regulatory transcription factor NRF2 (Nuclear factor erythroid-derived 2) regulates cellular bioenergetics and improves neuronal health in aging. Yet how NRF2 participates in maintaining synaptic, mitochondrial and cognitive function has not been fully elucidated. This study investigates how loss of NRF2 affects neuronal metabolism, synaptic density and cognitive performance in aged mice. Dendritic arborization as well as synaptic and mitochondrial gene expression was evaluated in hippocampal neurons isolated from mice lacking NRF2 (NRF2KO) and from wild-type (WT) C57BL6 mice. Mitochondrial function of these neurons was evaluated using the Seahorse XF platform. Additionally learning, memory and executive function were assessed in 20month old NRF2KO and age-matched WT mice using conditioned fear response (CFR) and odor discrimination reversal learning (ODRL) tests. Hippocampal bioenergetics was profiled using mitochondria isolated from these animals and tissue was harvested for assessment of mitochondrial and synaptic genes. NRF2KO neurons had reduced dendritic complexity and diminished synaptic gene expression. This was accompanied by impaired mitochondrial function and decreased mitochondrial gene expression. Similar mitochondrial deficits were observed in the brains of aged NRF2KO mice. These animals also had significantly impaired cognitive performance and reduced synaptic gene expression as well. These data point to a role for NRF2 in maintaining mitochondrial and cognitive function during aging and suggest that the transcription factor may be a viable target for cognitive enhancing interventions. Because mitochondrial dysfunction and cognitive impairment also occur together in many neurodegenerative conditions there may be broad therapeutic potential of NRF2 activating agents.

δ-Aminolevulinate induces fetal hemoglobin expression by enhancing cellular heme biosynthesis.

Sickle cell disease (SCD) and β-thalassemia are inherited blood disorders caused by genetic defects in the β-globin gene on chromosome 11, producing severe disease in people worldwide. Induction of fetal hemoglobin consisting of two α-globin and two γ-globin chains ameliorates the clinical symptoms of both disorders. In the present study, we investigated the ability of δ-aminolevulinate (ALA), the heme precursor, to activate γ-globin gene expression as well as its effects on cellular functions in erythroid cell systems. We demonstrated that ALA induced γ-globin expression at both the transcriptional and protein levels in the KU812 erythroid cell line. Using inhibitors targeting two enzymes in the heme biosynthesis pathway, we showed that cellular heme biosynthesis was involved in ALA-mediated γ-globin activation. Moreover, the transcription factor NRF2 (nuclear factor [erythroid-derived 2]-like 2), a critical regulator of the cellular antioxidant response, was activated by ALA and contributed to mechanisms of γ-globin activation; ALA did not affect cell proliferation and was not toxic to cells. Subsequent studies demonstrated ALA-induced γ-globin activation in erythroid progenitors generated from normal human CD34+ stem cells. These data support future study to explore the potential of stimulating intracellular heme biosynthesis by ALA or similar compounds as a novel therapeutic strategy for treating SCD and β-thalassemia. Impact statement Inherited mutations in the β-globin-like genes result in the most common forms of genetic blood disease including sickle cell disease (SCD) and β-thalassemia worldwide. Therefore, effective inexpensive therapies that can be distributed widely are highly desirable. Currently, drug-mediated fetal hemoglobin (HbF) induction can ameliorate clinical symptoms of SCD and β-thalassemia and is the most effective strategy for developing new therapeutic options. In the current study, we confirmed that δ-Aminolevulinate (ALA), the precursor of heme, induces γ-globin expression at both the transcriptional and translational levels in primary human erythroid progenitors. Moreover, the results indicate activation of the transcription factor NRF2 (nuclear factor (erythroid-derived 2)-like 2) by ALA to enhance HbF expression. These data support future study to explore the potential of stimulating intracellular heme biosynthesis by ALA or similar compounds as a novel therapeutic strategy for treating SCD and β-thalassemia.

Lipoic Acid Prevents High-Fat Diet-Induced Hepatic Steatosis in Goto Kakizaki Rats by Reducing Oxidative Stress Through Nrf2 Activation.

Prevention of hepatic fat accumulation may be an important approach for liver diseases due to the increased relevance of hepatic steatosis in this field. This study was conducted to investigate the effects of the antioxidant α-lipoic acid (α-LA) on hepatic steatosis, hepatocellular function, and oxidative stress in a model of type 2 diabetes fed with a high fat diet (HFD). Goto-Kakizaki rats were randomly divided into four groups. The first group received only a standard rat diet (control GK) including groups 2 (HFD), 3 (vehicle group), and 4 (α-LA group), which were given HFD, ad libitum during three months. Wistar rats are the non-diabetic control group. Carbohydrate and lipid metabolism, liver function, plasma and liver tissue malondialdehyde (MDA), liver GSH, tumor necrosis factor-α (TNF-α) and nuclear factor E2 (erythroid-derived 2)-related factor-2 (Nrf2) levels were assessed in the different groups. Liver function was assessed using quantitative hepatobiliary scintigraphy, serum aspartate, and alanine aminotransferases (AST, ALT), alkaline phosphatase, gamma-glutamyltranspeptidase, and bilirubin levels. Histopathologically steatosis and fibrosis were evaluated. Type 2 diabetic animals fed with HFD showed a marked hepatic steatosis and a diminished hepatic extraction fraction and both were fully prevented with α-LA. Plasma and liver tissue MDA and hepatic TNF-α levels were significantly higher in the HFD group when compared with the control group and significantly lower in the α-LA group. Systemic and hepatic cholesterol, triglycerides, and serum uric acid levels were higher in hyperlipidemic GK rats and fully prevented with α-LA. In addition, nuclear Nrf2 activity was significantly diminished in GK rats and significantly augmented after α-LA treatment. In conclusion, α-LA strikingly ameliorates steatosis in this animal model of diabetes fed with HFD by decrementing the inflammatory marker TNF-α and reducing oxidative stress. α-LA might be considered a useful therapeutic tool to prevent hepatic steatosis by incrementing antioxidant defense systems through Nrf2 and consequently decreasing oxidative stress and inflammation in type 2 diabetes.

The cytoprotective role of DJ-1 and p45 NFE2 against human primary alveolar type II cell injury and emphysema

Emphysema is characterized by irreversibly enlarged airspaces and destruction of alveolar walls. One of the factors contributing to this disease pathogenesis is an elevation in extracellular matrix (ECM) degradation in the lung. Alveolar type II (ATII) cells produce and secrete pulmonary surfactants and proliferate to restore the epithelium after damage. We isolated ATII cells from control non-smokers, smokers and patients with emphysema to determine the role of NFE2 (nuclear factor, erythroid-derived 2). NFE2 is a heterodimer composed of two subunits, a 45 kDa (p45 NFE2) and 18 kDa (p18 NFE2) polypeptides. Low expression of p45 NFE2 in patients with emphysema correlated with a high ECM degradation. Moreover, we found that NFE2 knockdown increased cell death induced by cigarette smoke extract. We also studied the cross talk between p45 NFE2 and DJ-1. DJ-1 protein is a redox-sensitive chaperone that protects cells from oxidative stress. We detected that cigarette smoke significantly increased p45 NFE2 levels in DJ-1 KO mice compared to wild-type mice. Our results indicate that p45 NFE2 expression is induced by exposure to cigarette smoke, has a cytoprotective activity against cell injury, and its downregulation in human primary ATII cells may contribute to emphysema pathogenesis.

Phycocyanin Protects Against UVB-induced Apoptosis Through the PKC α/βII-Nrf-2/HO-1 Dependent Pathway in Human Primary Skin Cells.

Phycocyanin (Pc) is one of the active pigment constituents of Spirulina microalgae. It has been used for its potent antioxidant and anti-inflammatory properties. However, the protective effects of Pc against ultraviolet-B (UVB)-induced primary skin cells damage are still undefined. In the present study, we investigated whether Pc prevented UVB-induced apoptotic cell death in human dermal fibroblasts (HDF) and human epidermal keratinocytes (HEK). Pc induced the transcription of heme oxygenase-1 (HO-1). Furthermore, Pc treatments resulted in a marked increase in nuclear factor erythroid-derived 2 (NF-E2)-like 2 (Nrf-2) nuclear translocation. Also, Pc protected UVB induced apoptosis and reduced the p53 and Bax levels, as well as caspase-3 activation. Pc treatment showed a significantly enhanced effect on the phosphorylation of protein kinase C (PKC) α/β II, but not that of p38 mitogen-activated protein kinase (MAPK) or Akt. Induction of HO-1 induced by Pc was suppressed by Go6976, a selective inhibitor of PKC α/β II. In addition, knockdown of HO-1 by small interfering (siRNA) caused a significant increase in poly (ADP-ribose) polymerase 1 (PARP-1) cleavage and caspase-3 activation after Pc pretreatment. Taken together, our results demonstrate that Pc-induced expression of HO-1 is mediated by the PKC α/β II-Nrf-2/HO-1 pathway, and inhibits UVB-induced apoptotic cell death in primary skin cells.

Nuclear Factor Erythroid 2 Regulates Human HSC Self-Renewal and T Cell Differentiation by Preventing NOTCH1 Activation.

SummaryNuclear factor erythroid-derived 2 (NF-E2) has been associated with megakaryocyte maturation and platelet production. Recently, an increased in NF-E2 activity has been implicated in myeloproliferative neoplasms. Here, we investigate the role of NF-E2 in normal human hematopoiesis. Knockdown of NF-E2 in the hematopoietic stem and progenitor cells (HSPCs) not only reduced the formation of megakaryocytes but also drastically impaired hematopoietic stem cell activity, decreasing human engraftment in immunodeficient (NSG) mice. This phenotype is likely to be related to both increased cell proliferation (p21-mediated) and reduced Notch1 protein expression, which favors HSPC differentiation over self-renewal. Strikingly, although NF-E2 silencing in HSPCs did not affect their myeloid and B cell differentiation in vivo, it almost abrogated T cell production in primary hosts, as confirmed by in vitro studies. This effect is at least partly due to Notch1 downregulation in NF-E2-silenced HSPCs. Together these data reveal that NF-E2 is an important driver of human hematopoietic stem cell maintenance and T lineage differentiation.

P45 NF-E2 regulates syncytiotrophoblast differentiation by post-translational GCM1 modifications in human intrauterine growth restriction

Placental insufficiency jeopardizes prenatal development, potentially leading to intrauterine growth restriction (IUGR) and stillbirth. Surviving fetuses are at an increased risk for chronic diseases later in life. IUGR is closely linked with altered trophoblast and placental differentiation. However, due to a paucity of mechanistic insights, suitable biomarkers and specific therapies for IUGR are lacking. The transcription factor p45 NF-E2 (nuclear factor erythroid derived 2) has been recently found to regulate trophoblast differentiation in mice. The absence of p45 NF-E2 in trophoblast cells causes IUGR and placental insufficiency in mice, but mechanistic insights are incomplete and the relevance of p45 NF-E2 for human syncytiotrophoblast differentiation remains unknown. Here we show that p45 NF-E2 negatively regulates human syncytiotrophoblast differentiation and is associated with IUGR in humans. Expression of p45 NF-E2 is reduced in human placentae complicated with IUGR compared with healthy controls. Reduced p45 NF-E2 expression is associated with increased syncytiotrophoblast differentiation, enhanced glial cells missing-1 (GCM1) acetylation and GCM1 desumoylation in IUGR placentae. Induction of syncytiotrophoblast differentiation in BeWo and primary villous trophoblast cells with 8-bromo-adenosine 3′,5′-cyclic monophosphate (8-Br-cAMP) reduces p45 NF-E2 expression. Of note, p45 NF-E2 knockdown is sufficient to increase syncytiotrophoblast differentiation and GCM1 expression. Loss of p45 NF-E2 using either approach resulted in CBP-mediated GCM1 acetylation and SENP-mediated GCM1 desumoylation, demonstrating that p45 NF-E2 regulates post-translational modifications of GCM1. Functionally, reduced p45 NF-E2 expression is associated with increased cell death and caspase-3 activation in vitro and in placental tissues samples. Overexpression of p45 NF-E2 is sufficient to repress GCM1 expression, acetylation and desumoylation, even in 8-Br-cAMP exposed BeWo cells. These results suggest that p45 NF-E2 negatively regulates differentiation and apoptosis activation of human syncytiotrophoblast by modulating GCM1 acetylation and sumoylation. These studies identify a new pathomechanism related to IUGR in humans and thus provide new impetus for future studies aiming to identify new biomarkers and/or therapies of IUGR.

Nrf2 activation in the treatment of neurodegenerative diseases: a focus on its role in mitochondrial bioenergetics and function.

The nuclear factor erythroid-derived 2 (NF-E2)-related factor 2 (Nrf2) is a transcription factor well-known for its function in controlling the basal and inducible expression of a variety of antioxidant and detoxifying enzymes. As part of its cytoprotective activity, increasing evidence supports its role in metabolism and mitochondrial bioenergetics and function. Neurodegenerative diseases are excellent candidates for Nrf2-targeted treatments. Most neurodegenerative conditions such as Alzheimer's disease, Parkinson's disease, amyotrophic lateral sclerosis, frontotemporal dementia and Friedreich's ataxia are characterized by oxidative stress, misfolded protein aggregates, and chronic inflammation, the common targets of Nrf2 therapeutic strategies. Together with them, mitochondrial dysfunction is implicated in the pathogenesis of most neurodegenerative disorders. The recently recognized ability of Nrf2 to regulate intermediary metabolism and mitochondrial function makes Nrf2 activation an attractive and comprehensive strategy for the treatment of neurodegenerative disorders. This review aims to focus on the potential therapeutic role of Nrf2 activation in neurodegeneration, with special emphasis on mitochondrial bioenergetics and function, metabolism and the role of transporters, all of which collectively contribute to the cytoprotective activity of this transcription factor.

Individual and combined antioxidant effects of ginsenoside F2 and cyanidin-3-O-glucoside in human embryonic kidney 293 cells

Ginsenosides and anthocyanins have already been reported to exhibit protective effects on intracellular defense against oxidative stress. Nuclear factor erythroid-derived 2 (NF-E2)-like 2 (Nrf2) plays a key role in signal pathways to counteract oxidative stress and controls expression of antioxidant enzymes. The present study is aimed at investigating the individual and combined antioxidant effects of ginsenoside F2 (F2) and cyanidin-3-O-glucoside (C3G) against H2O2-induced oxidative stress in Human Embryonic Kidney (HEK-293) cells. Cell viability, MDA level and activities of antioxidant enzymes were measured using corresponding assay kits. A DCFH-DA fluorescent probe assay was used to measure the level of intracellular reactive oxygen species (ROS). Quantitative real-time PCR and Western blotting were used to detect the expression of Nrf2 and Kelch-like ECH associated protein 1 (Keap1). The results showed that F2 and C3G significantly inhibited the generation of MDA and intracellular ROS, and increased the activities of antioxidant enzymes. Furthermore, F2 and C3G significantly enhanced the protein and mRNA expressions of Nrf2 and reduced the expressions of Keap1 in a concentration-dependent manner. On the basis of the stronger individual effects, synergistic effects were present in the combinations of F2 and C3G. In conclusion, these results demonstrated that F2 and C3G can protect HEK-293 cells against H2O2-induced oxidative stress and possibly act synergistically through reducing intracellular ROS, as well as activating the Nrf2/Keap1 signaling pathway and increasing antioxidant enzyme levels.

Transcription Factor Nrf2: a novel target to modulate inflammatory and neuroprotective responses in Parkinson's disease.

Stopping the succession of events that lead to development of Parkinson’s disease (PD) is a principal challenge that requires a brain protective approach in early diagnosed patients. Although PD ethiopathology may not have a single causative factor, information from sporadic and familial cases together with chemical and genetic animal models strongly suggests that low-grade chronic inflammation and oxidative stress play a critical role. Our team is studying the relevance of the transcription factor NRF2 (Nuclear factor (erythroid-derived 2)-like 2), a master regulator of oxidant and inflammatory defense, as a new therapeutic target in PD. The pro-inflammatory activation of microglia and astroglia in response to LPS, MPTP and human α-synuclein over-expression is exacerbated in Nrf2-deficient mice, thus demonstrating an immunomodulatory role of this protein. In PD patients, some evidence gathered from epidemiological, genetic and anatomopathologic studies also support a protective role of NRF2. Several compounds activate NRF2 and provide an immunomodulator and cytoprotective response in preclinical animal models of PD. At this time a crucial point to translate these promising results to the clinic is the discovery of a drug with good pharmacokinetics and pharmacodynamics that fulfill criteria of safety, tolerability and efficacy. The use of repurposing drugs, such as dimethyl fumarate used nowadays for treatment of remitting relapsing multiple sclerosis, may provide excellent candidates.

The Mutatome of CBFB/MYH11-rearranged Acute Myeloid Leukemia (AML)

The fusion gene CBFB/MYH11 results from a pericentric inversion of chromosome 16, inv(16)(p13.1q22), or less commonly from a t(16;16)(p13.1;q22). This rearrangement is found in 6-8% of adult de novo AML cases and associated with favourable prognosis. Physiologically, CBFB binds to RUNX1 forming the core binding factor (CBF), which is a transcription factor essential for normal hematopoiesis and myeloid development. By disrupting transcription factor activity of CBF, the CBFB/MYH11 fusion protein causes repression of the CBF-dependent target genes resulting in a block of differentiation. Since expression of CBFB/MYH11 alone is not sufficient to cause leukemia it is likely that additional mutations are required for malignant transformation.To systematically identify non-silent mutations, which may collaborate with CBFB/MYH11 during leukemogenesis, we performed whole exome sequencing (WES) of 9 adult AML samples with inv(16) or t(16;16) and matched remission samples. Using this approach, we found 4-11 leukemia-specific sequence variants per patient (median: 6 mutations). These include mutations in genes known to cooperate with CBFB/MYH11 [e.g. NRAS (n=4), KRAS (n=4), FLT3 (n=2), KIT (n=1)] as well as in genes, which have not been described as mutated in AML so far (e.g. ZFHX4, NFE2).To test for recurrent mutations in selected genes, we designed a custom targeted resequencing assay (Haloplex, Agilent), comprising candidate genes from exome sequencing, as well as genes known to be recurrently mutated in AML (129 genes, 396.45 kbp total target sequence). We performed targeted deep amplicon sequencing on the diagnostic samples from 68 CBFB/MYH11-rearranged AML patients with a median read depth of 645. The results are summarized in Figure 1. Twenty-six genes were found mutated in at least 2 patients. The mutation frequencies of NRAS (35%), KRAS (21%), FLT3 (27%), KIT (22%) and WT1 (9%) were similar to previous reports. In addition, we found recurrent mutations with frequencies of above 5% in FAT1 (6%), PTPN11 (6%), NFE2 (6%) and ZFHX4 (6%). Recently, acquired NFE2 (Nuclear Factor, Erythroid-Derived 2) mutations were described in 2-3% of myeloproliferative neoplasms (MPN) cases. These truncating NFE2 mutations confer a proliferative advantage (Jutzi et al., 2013, JEM). ZFHX4 (Zinc Finger Homeobox 4) is required for the maintenance of tumor initiating cells in glioblastoma (Chudnovsky et al., 2014, Cell Rep). In 59% (40/68) of CBFB/MYH11-rearranged patients, more than one additional mutation was identified, but each of them at a distinct variant allele-frequency, indicating clonal heterogeneity.Recurrent mutations described in RUNX1/RUNX1T1-rearranged leukemia (Krauth et al., 2014, Leukemia, n= 139 patients, Micol et al., 2014, Blood, n= 110 patients) affecting genes such as IDH1/2 (4%), JAK2 (3%), ASXL1 (12%) and the recently described ASXL2 (23%) mutation were not found in our patients with CBFB/MYH11-rearranged CBF leukemia or considerably underrepresented (IDH1/2 0%, JAK2 0%, ASXL1 3%, ASXL2 0%). Commonly mutated genes in CBF leukemia like RAS-genes and FLT3 could be detected at higher frequency in our CBFB/MYH11 cohort (RAS-genes: 56% vs. 17%, FLT3: 27 vs. 13%), whereas KIT mutations occur in similar frequency (22% vs. 17-32%).Furthermore, we performed custom targeted resequencing in corresponding relapse samples from 7 patients with inv(16) in order to assess the clonal evolution. Surprisingly, all mutations in kinase genes [NRAS (n=1), KIT (n=2), FLT3 (n=3)] detected in 6 out of 7 cases at diagnosis were lost at relapse. Of note, one of these patients acquired mutations in WT1 and ZFHX4 and another patient acquired a CBL mutation at relapse.Taken together, our findings suggest that the mutatome of CBFB/MYH11-rearranged AML is genetically complex with co-existence of different subclones at diagnosis. Mutations in kinase genes such as NRAS, KIT, FLT3 seem to be unstable during disease progression and the actual driver of relapse remains elusive in many cases. [Display omitted] DisclosuresNo relevant conflicts of interest to declare.

RUNX1 and NF-E2 upregulation is not specific for MPNs, but is seen in polycythemic disorders with augmented HIF signaling

AbstractOverexpression of transcription factors runt-related transcription factor 1 (RUNX1) and nuclear factor, erythroid-derived 2 (NF-E2) was reported in granulocytes of patients with polycythemia vera and other myeloproliferative neoplasms (MPNs). Further, a transgenic mouse overexpressing the NF-E2 transgene was reported to be a model of MPN. We hypothesized that increased transcripts of RUNX1 and NF-E2 might characterize other polycythemic states with primary polycythemic features, that is, those with exaggerated erythropoiesis due to augmented erythropoietin (EPO) sensitivity. We tested the expression of RUNX1 and NF-E2 in polycythemic patients of diverse phenotypes and molecular causes. We report that RUNX1 and NF-E2 overexpression is not specific for MPN; these transcripts were also significantly elevated in polycythemias with augmented hypoxia-inducible factor activity whose erythroid progenitors were hypersensitive to EPO. RUNX1 and NF-E2 overexpression was not detected in patients with EPO receptor (EPOR) gain-of-function, suggesting distinct mechanisms by which erythroid progenitors in polycythemias with defects of hypoxia sensing and EPOR mutations exert their EPO hypersensitivity.

Characterization of a Novel Long Noncoding RNA, SCAL1, Induced by Cigarette Smoke and Elevated in Lung Cancer Cell Lines

The incidence of lung diseases and cancer caused by cigarette smoke is increasing. The molecular mechanisms of gene regulation induced by cigarette smoke that ultimately lead to cancer remain unclear. This report describes a novel long noncoding RNA (lncRNA) that is induced by cigarette smoke extract (CSE) both in vitro and in vivo and is elevated in numerous lung cancer cell lines. We have termed this lncRNA the smoke and cancer-associated lncRNA-1 (SCAL1). This lncRNA is located in chromosome 5, and initial sequencing analysis reveals a transcript with four exons and three introns. The expression of SCAL1 is regulated transcriptionally by nuclear factor erythroid 2-related factor (NRF2), as determined by the small, interfering RNA (siRNA) knockdown of NRF2 and kelch-like ECH-associated protein 1 (KEAP1). A nuclear factor erythroid-derived 2 (NF-E2) motif was identified in the promoter region that shows binding to NRF2 after its activation. Functionally, the siRNA knockdown of SCAL1 in human bronchial epithelial cells shows a significant potentiation of cytotoxicity induced by CSE in vitro. Altogether, these results identify a novel and intriguing new noncoding RNA that may act downstream of NRF2 to regulate gene expression and mediate oxidative stress protection in airway epithelial cells.

Nrf2 activation is associated with Z-DNA formation in the human HO-1 promoter

Using a luciferase reporter assay, we previously demonstrated that a Z-DNA-forming sequence of alternating thymine–guanine repeats in the human heme oxygenase-1 gene (HO-1) promoter is involved in nuclear factor erythroid-derived 2 (NF-E2)–related factor 2 (Nrf2)-mediated HO-1 promoter activation. However, the actual Z-DNA formation in this native genomic locus has not been experimentally demonstrated. To detect Z-DNA formation in vivo, we generated a construct containing the Z-DNA-binding domain of human adenosine deaminase acting on double-stranded RNA 1 fused with enhanced green fluorescence protein, designated as the Z-probe. A chromatin immunoprecipitation assay using an anti-GFP antibody showed that the Z-probe detects the well-characterized Z-DNA formation in the CSF1 promoter. Using this detection system, we demonstrated that the glutathione-depleting agent, diethyl maleate, induced Nrf2-dependent Z-DNA formation in the HO-1 promoter, but not in the thioredoxin reductase 1 gene promoter. Moreover, a time course analysis revealed that Z-DNA formation precedes HO-1 transcriptional activation. Concurrent with Z-DNA formation, nucleosome occupancy was reduced, and the recruitment of RNA polymerase II was enhanced in the HO-1 promoter region, suggesting that Z-DNA formation enhances HO-1 gene transcription. Furthermore, Nrf2-induced BRG1 recruitment to the HO-1 promoter temporarily occurred simultaneously with Z-DNA formation. Thus, these results implicate Nrf2-dependent Z-DNA formation in HO-1 transcriptional activation and suggest the involvement of BRG1 in Z-DNA formation.

Phosphorylation-Dependent SUMOylation of the Transcription Factor NF-E2

Nuclear factor erythroid-derived 2 (NF-E2), a heterodimer composed of p45 and p18, is a transcriptional activator in hematopoietic progenitors. The transcriptional activity of NF-E2 is not only upregulated by SUMOylation but also stimulated by the cAMP-dependent protein kinase A (PKA). However, the relationship between SUMOylation and phosphorylation in the activation of NF-E2 is unclear. In the present studies, we have demonstrated that PKA enhances NF-E2 SUMOylation in an in vitro system using purified proteins, suggesting a possible mechanism for PKA-dependent activation of the NF-E2 transcription factor through SUMOylation.

The Heme Oxygenase 1 Inducer (CoPP) Protects Human Cardiac Stem Cells against Apoptosis through Activation of the Extracellular Signal-regulated Kinase (ERK)/NRF2 Signaling Pathway and Cytokine Release

Intracoronary delivery of c-kit-positive human cardiac stem cells (hCSCs) is a promising approach to repair the infarcted heart, but it is severely limited by the poor survival of donor cells. Cobalt protoporphyrin (CoPP), a well known heme oxygenase 1 inducer, has been used to promote endogenous CO generation and protect against ischemia/reperfusion injury. Therefore, we determined whether preconditioning hCSCs with CoPP promotes CSC survival. c-kit-positive, lineage-negative hCSCs were isolated from human heart biopsies. Lactate dehydrogenase release assays demonstrated that preconditioning CSCs with CoPP markedly enhanced cell survival after oxidative stress induced by H(2)O(2), concomitant with up-regulation of heme oxygenase 1, COX-2, and anti-apoptotic proteins (BCL2, BCL2-A1, and MCL-1) and increased phosphorylation of NRF2. Apoptotic cytometric assays showed that pretreatment of CSCs with CoPP enhanced the cells' resistance to apoptosis induced by oxidative stress. Conversely, knocking down HO-1, COX-2, or NRF2 by shRNA gene silencing abrogated the cytoprotective effects of CoPP. Further, preconditioning CSCs with CoPP led to a global increase in release of cytokines, such as EGF, FGFs, colony-stimulating factors, and chemokine ligand. Conditioned medium from cells pretreated with CoPP conferred naive CSCs remarkable resistance to apoptosis, demonstrating that cytokines released by preconditioned cells play a key role in the anti-apoptotic effects of CoPP. Preconditioning CSCs with CoPP also induced an increase in the phosphorylation of Erk1/2, which are known to modulate multiple pro-survival genes. These results potentially provide a simple and effective strategy to enhance survival of CSCs after transplantation and, therefore, their efficacy in repairing infarcted myocardium.

Abnormal differentiation of erythroid precursors in p45 NF-E2−/− mice

The transcription factor p45 nuclear factor-erythroid-derived 2 (NF-E2) plays major roles in erythroid and megakaryocytic lineages. Here, we investigated the role of p45 NF-E2 in erythroid differentiation in vivo. Absence of p45 NF-E2 in mice leads to a twofold increase in serum erythropoietin levels. In the bone marrow of these animals, we found a different distribution of precursor populations compared to wild-type mice, suggesting abnormal differentiation. Loss of p45 NF-E2 was also associated with an increase in splenic erythropoiesis, as evidenced by an accumulation of early precursors, namely, late basophilic and polychromatic erythroblasts. These observations are consistent with a stress erythropoiesis phenotype and indicate that the spleen is likely compensating for ineffective erythropoiesis in the bone marrow. Analysis of bone marrow samples revealed increased GATA1 levels, as well as an increased proportion of erythroid cells arrested at the G(1) stage of cell cycle in p45 NF-E2-deficient mice. These results suggest that p45 NF-E2 is required for the differentiation of erythroid precursors.