Egr-1 Pathway Research Articles

Establishment and characterization of a patient-derived solitary fibrous tumor/hemangiopericytoma cell line model.

Solitary fibrous tumor/Hemangiopericytoma (SFT/HPC) is a rare subtype of soft tissue sarcoma harboring NAB2-STAT6 gene fusions. Mechanistic studies and therapeutic development on SFT/HPC are impeded by scarcity and lack of system models. In this study, we established and characterized a novel SFT/HPC patient-derived cell line (PDC), SFT-S1, and screened for potential drug candidates that could be repurposed for the treatment of SFT/HPC. Immunohistochemistry profiles of the PDC was consistent with the patient's tumor sample (CD99+/CD34+/desmin-). RNA sequencing, followed by Sanger sequencing confirmed the pathognomonic NAB2exon3-STAT6exon18 fusion in both the PDC and the original tumor. Transcriptomic data showed strong enrichment for oncogenic pathways (epithelial-mesenchymal transition, FGF, EGR1 and TGFβ signaling pathways) in the tumor. Whole genome sequencing identified potentially pathogenic somatic variants such as MAGEA10 and ABCA2. Among a panel of 14 targeted agents screened, dasatinib was identified to be the most potent small molecule inhibitor against the PDC (IC50, 473 nM), followed by osimertinib (IC50, 730 nM) and sunitinib (IC50, 1765 nM). Methylation profiling of the tumor suggests that this specific variant of SFT/HPC could lead to genome-wide hypomethylation. In conclusion, we established a novel PDC model of SFT/HPC with comprehensive characterization of its genomic, epigenomic and transcriptomic landscape, which can facilitate future preclinical studies of SFT/HPC, such as in vitro drug screening and in vivo drug testing.

S14G-Humanin ameliorates ovalbumin-induced airway inflammation in asthma mediated by inhibition of toll-like receptor 4 (TLR4) expression and the nuclear factor κ-B (NF-κB)/early growth response protein-1 (Egr-1) pathway.

Asthma is a chronic inflammatory disease with a high morbidity rate in children and significantly impacts their healthy growth. It is reported that Th2 cell-mediated airway inflammation and activated oxidative stress are involved in the pathogenesis of asthma. S14G-humanin (HNG) is a derivative of Humanin with higher activity. The present study proposes to explore the potential treating property of HNG on asthma. An asthma model was constructed in mice using ovalbumin (OVA), the mice were treated with 2.5 mg/kg and 5 mg/kg HNG for 16 days. Dramatically increased lung weight index, elevated number of monocytes, eosinophils, and neutrophils, promoted production of Th2 cytokines including interleukin-4 (IL-4), interleukin-5 (IL-5), and interleukin-13 (IL-13), and severe histological pathology were observed in OVA-challenged mice, all of which were extremely alleviated by 2.5 mg/kg and 5 mg/kg HNG. Furthermore, the increased malondialdehyde (MDA) level and declined superoxide dismutase (SOD) activity in OVA-challenged mice were abolished by 2.5 mg/kg and 5 mg/kg HNG. Lastly, the upregulated TLR4, p-NF-κB p65, and early growth response 1 (Egr-1) in lung tissues of OVA-challenged mice were pronouncedly downregulated by 2.5 mg/kg and 5 mg/kg HNG. Collectively, our data suggested that HNG ameliorated airway inflammation in asthma partially due to NF-κB and Egr-1-mediated responses.

Cholinergic drugs reduce metabolic inflammation and diabetic myocardial injury by regulating the gut bacterial component lipopolysaccharide-induced ERK/Egr-1 pathway.

Autonomic imbalance and metabolic inflammation are important pathological processes in diabetic cardiomyopathy. Gut microbiota dysbiosis and increased levels of bacterial component lipopolysaccharide (LPS) are associated with diabetic myocardial injury, but the mechanism by which gut microbes affect metabolic inflammation and cardiac injury remains unclear. We determined whether pyridostigmine (PYR), which inhibits cholinesterase to improve vagal activity, could regulate the disordered gut microbiota and attenuate gut barrier dysfunction, metabolic endotoxemia, and inflammation in diabetes. Db/db mice exhibited high blood glucose levels, insulin resistance, low vagal activity, and diabetic myocardial injury. Db/db mice also exhibited gut microbiota perturbations and subsequent disruption of gut barrier function, resulting in an influx of LPS, metabolic endotoxemia, and inflammation. PYR ameliorated the dysregulated glucose and lipid metabolism, modulated the overall structure of the gut microbiota, selectively enhanced the abundance of anti-inflammatory bacteria, and reduced the abundance of proinflammatory and potentially pathogenic bacteria in db/db mice. Importantly, PYR enhanced vagal activity, restored gut microbiota homeostasis, and alleviated gut barrier dysfunction. Therefore, the LPS-induced extracellular signal-regulated kinase (ERK)/early growth response-1 (Egr-1) pathway and consequent metabolic inflammation were inhibited, and eventually, cardiac hypertrophy, fibrosis, oxidative stress, and dysfunction were ameliorated in db/db mice. In vitro cardiomyocyte injury was induced by exposing primary neonatal rat ventricular cardiomyocytes to high glucose (HG) and LPS. In vitro analyses showed that HG + LPS induced ERK1/2 phosphorylation, Egr-1 expression, inflammation, and cell apoptosis, which were inhibited by acetylcholine (ACh). Alpha 7 nicotinic ACh receptor but not muscarinic 2 ACh receptor plays an important role in ACh-mediated anti-inflammatory effects and inhibiting the ERK/Egr-1 pathway in HG + LPS-administered neonatal rat ventricular cardiomyocytes. PYR and ACh ameliorated diabetic myocardial injury by inhibiting the LPS-induced ERK/Egr-1 pathway and metabolic inflammation. The vagus-gut-heart axis has provided new insights into the complex mechanisms of diabetes and offers novel therapeutic targets.

MOTS-c repairs myocardial damage by inhibiting the CCN1/ERK1/2/EGR1 pathway in diabetic rats.

Cardiac structure remodeling and dysfunction are common complications of diabetes, often leading to serious cardiovascular events. MOTS-c, a mitochondria-derived peptide, regulates metabolic homeostasis by accelerating glucose uptake and improving insulin sensitivity. Plasma levels of MOTS-c are decreased in patients with diabetes. MOTS-c can improve vascular endothelial function, making it a novel therapeutic target for the cardiovascular complications of diabetes. We investigated the effects of MOTS-c on cardiac structure and function and analyzed transcriptomic characteristics in diabetic rats. Our results indicate that treatment with MOTS-c for 8-week repaired myocardial mitochondrial damage and preserved cardiac systolic and diastolic function. Transcriptomic analysis revealed that MOTS-c altered 47 disease causing genes. Functional enrichment analysis indicated MOTS-c attenuated diabetic heart disease involved apoptosis, immunoregulation, angiogenesis and fatty acid metabolism. Moreover, MOTS-c reduced myocardial apoptosis by downregulating CCN1 genes and thereby inhibiting the activation of ERK1/2 and the expression of its downstream EGR1 gene. Our findings identify potential therapeutic targets for the treatment of T2D and diabetic cardiomyopathy.

Mots-c Attenuates Myocardial Mitochondrial Damage Through Inhibition Of Ccn1/erk1/2/egr1 Pathway

Mitochondrial dysfunction is considered as a major contributor to cardiac systolic and diastolic dysfunction in diabetes. As a newly identified mitochondria derived peptide, MOTS-c plays a vital role in the regulation of metabolic homeostasis and was shown to be closely related to type 2 diabetes (T2D). We hypothesized that MOTS-c could prevent myocardial mitochondrial damage and improve cardiac structure and function in T2D. PURPOSE: To explored the effects and molecular mechanisms of MOTS-c on mitochondrial damage and cardiac dysfunction in diabetes. METHODS: Thirty male Sprague Dawley rats were randomly divided into three groups: control (C, n = 10), diabetes (D, n = 10) and diabetes plus MOTS-c treatment (DM, n = 10). Diabetic rats induced by high-fat high-sugar diet combined with a low-dose streptozotocin (30 mg/kg) injection. Rats in DM group were injected with MOTS-c at a dose of 0.5 mg/kg/day and 7 days/week for 8 weeks. Echocardiography was used to measured cardiac systolic and diastolic function, and transmission electron microscopy (TEM) was used to observed myocardial ultrastructure. RNA sequencing was used to determin differentially expressed genes (DEGs). Gene Ontology (GO) were selected for functional enrichment analysis to screen out the related pathways and genes, and qRT-PCR was used to measure the mRNA expression levels of CCN1, ERK1/2 and EGR1. RESULTS: MOTS-c treatment significantly prevented mitochondrial swelling and vacuoles and repaired the disorder of myocardial fiber arrangement. There was no significant differences in ejection fraction (EF), E-wave peak, A-wave peak and E/A ratio between DM and C groups (all p > 0.05). 8-week MOTS-c treatment altered 47 causative genes in myocardium of diabetic rats. The results of GO enrichment analysis showed that CCN1 and EGR1 were highly expressed and appeared in the apoptosis related terms. CCN1 was included in the ERK1/2 cascade with the highest significance. The mRNA expression of CCN1, ERK2 and EGR1 were significantly decreased after MOTS-c treatment (p < 0.01). CONCLUSIONS: MOTS-c improves myocardial mitochondrial damage and attenuates the cardiac pathological remodeling and dysfunction. CCN1/ERK1/2/EGR1 pathway may play an important role in MOTS-c preventing myocardial damage in diabetes.

Disrupting circ-GNB4 mitigates high glucose-induced human mesangial cells injury by regulating the proliferation, ECM accumulation, inflammation and oxidative stress through circ-GNB4/miR-23c/EGR1 pathway.

Journal of Cardiovascular Pharmacology ():10.1097/FJC.0000000000001350, August 20, 2022. | DOI: 10.1097/FJC.0000000000001350

ACT001 reverses resistance of prolactinomas via AMPK-mediated EGR1 and mTOR pathways.

Dopamine agonist (DA) is the first choice for the treatment of prolactinomas, and drug resistance is unavoidable during treatment due to the heterogeneity of tumors. The two prolactinoma cell lines (GH3 cells and MMQ cells) were found to have different sensitivity and responding modes to the cabergoline (CAB) and bromocriptine (BRC). In this research, we disclosed the capability of ACT001, a derivative of parthenolide analogs, to activate AMPK by increasing the intracellular reactive oxygen species (ROS) level and AMP/ATP ratio to reverse DA resistance through dual pathways in prolactinoma cells. The results indicated that ACT001 could reverse the CAB resistance in GH3 cells by inhibiting the mTOR signaling pathway, inducing cell death through autophagy, and reverse the BRC resistance in MMQ cells by activating the EGR1 signaling pathway, inducing cell death through apoptosis. Our results suggested that ACT001 is a promising therapeutic compound for treating DA-resistant prolactinomas.

Circular RNA _NLRP1 targets mouse microRNA-199b-3p to regulate apoptosis and pyroptosis of hippocampal neuron under oxygen-glucose deprivation exposure

ABSTRACT Primary hippocampal neuronal cells were used to establish cell model of cerebral ischemia under oxygen-glucose deprivation (OGD) treatment. After the cell model was pre-treated with short hairpin (sh)-circ_NLRP1 or mmu-miR-199b-3p inhibitor, LDH release and cell apoptosis were detected by LDH kit and TUNEL staining, respectively, while the expression of NLRP3 pyroptosis-related makers was analyzed through immunofluorescence (IF) assay and Western blot, respectively. The binding sites between circ_NLRP1 and mmu-miR-199b-3p were predicted and further validated by Dual Luciferase Reporter assay. Additionally, mitogen-activated protein kinase (MAPK) pathway was also analyzed by means of Western blot assay. Neuronal cells under OGD conditions released less lactate dehydrogenase (LDH) and showed less apoptosis status by silencing circ_NLRP1. In addition, gasdermin D (GSDMD)-N immunofluorescence staining showed weaker fluorescence intensity and decreased expression of pyroptosis-related mediators. We further found that mmu-miR-199b-3p-inhibitor could alter the effects of sh-circ_NLRP1 on hippocampal neuronal cells. In addition, in this process, extracellular signal-regulated kinase (ERK)/EGR1 pathway was also significantly affected. In conclusion, OGD stimulation induced neuronal damage and pyroptosis through enhancing circ_NLRP1 expression and further downregulating mmu-miR-199b-3p levels. The present study provided a novel insight for understanding the potential mechanism of ischemia-induced neuronal damage and for developing new drugs for treating brain ischemia damage.

Insulin Treatment Forces Arteriogenesis in Diabetes Mellitus by Upregulation of the Early Growth Response-1 (Egr-1) Pathway in Mice.

The process of arteriogenesis is severely compromised in patients with diabetes mellitus (DM). Earlier studies have reported the importance of Egr-1 in promoting collateral outward remodeling. However, the role of Egr-1 in the presence of DM in outward vessel remodeling was not studied. We hypothesized that Egr-1 expression may be compromised in DM which may lead to impaired collateral vessel growth. Here, we investigated the relevance of the transcription factor Egr-1 for the process of collateral artery growth in diabetic mice. Induction of arteriogenesis by femoral artery ligation resulted in an increased expression of Egr-1 on mRNA and protein level but was severely compromised in streptozotocin-induced diabetic mice. Diabetes mellitus mice showed a significantly reduced expression of Egr-1 endothelial downstream genes Intercellular Adhesion Molecule-1 (ICAM-1) and urokinase Plasminogen Activator (uPA), relevant for extravasation of leukocytes which promote arteriogenesis. Fluorescent-activated cell sorting analyses confirmed reduced leukocyte recruitment. Diabetes mellitus mice showed a reduced expression of the proliferation marker Ki-67 in growing collaterals whose luminal diameters were also reduced. The Splicing Factor-1 (SF-1), which is critical for smooth muscle cell proliferation and phenotype switch, was found to be elevated in collaterals of DM mice. Treatment of DM mice with insulin normalized the expression of Egr-1 and its downstream targets and restored leukocyte recruitment. SF-1 expression and the diameter of growing collaterals were normalized by insulin treatment as well. In summary, our results showed that Egr-1 signaling was impaired in DM mice; however, it can be rescued by insulin treatment.

Antitumor Effect of Periplocin in TRAIL‐Resistant gastric cancer cells via upregulation of death receptor through activating ERK1/2‐EGR1 pathway

Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL), a member of the tumor necrosis factor family, induces apoptosis in a variety of cancer cells. However, gastric cancer (GC) cells are insensitive to TRAIL usually. In the previous study, we showed that Periplocin could induce apoptosis in GC cells via the activation of ERK1/2-EGR1 pathway. In the present study, we have shown that the combination of Periplocin and TRAIL had a greater inhibitory effect on gastric cancer cell viability in vitro and in vivo than Periplocin or TRAIL alone. Through upregulating the expression of DR4 and DR5 at transcriptional and protein levels, Periplocin enhanced the sensitivity of gastric cancer cells to TRAIL. Furthermore, enhanced activity of ERK1/2-EGR1 pathway was responsible for upregulating of DR4 and DR5 uponPeriplocin treatment, subsequently reducing the expression of Mcl-1 and Bcl2 and activating Bid and caspase-3/8. Collectively, these data implied that Periplocin might act as a sensitizer of TRAIL and could be a potential strategy for the treatment of GC.

BAG3 contributes to HGF-mediated cell proliferation, migration, and invasion via the Egr1 pathway in gastric cancer.

Bcl2-associated athanogene 3 (BAG3) is elevated in several types of cancers. However, the role of BAG3 in progression of gastric cancer is unknown. Therefore, the present study aims to find out the role of BAG3 in hepatocyte growth factor (HGF)-mediated tumor progression and the molecular mechanisms by which HGF regulates BAG3 expression. BAG3 mRNA and protein were measured using reverse transcription polymerase chain reaction and Western blot in the 2 human gastric cancer cell lines, NUGC3 and MKN28, treated with or without HGF. The effects of BAG3 knockdown on cell proliferation, cell invasion, and apoptosis were analyzed by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, the in vitro 2-chamber invasion assay, and flow cytometry in BAG3 short hairpin RNA (shRNA)-transfected cells and control cells. The signaling pathways involved in BAG3 that are regulated by HGF were analyzed. The chromatin immunoprecipitation assay was used to determine binding of Egr1 to the BAG3 promoter. BAG3 mRNA and protein levels were increased following treatment with HGF. HGF-mediated BAG3 upregulation increased cell proliferation and cell invasion; however, it decreased apoptosis. HGF-mediated BAG3 upregulation is regulated by an ERK and Egr1-dependent pathway. BAG3 may have an important role in HGF-mediated cell proliferation and metastasis in gastric cancer through an ERK and Egr1-dependent pathway. This pathway may provide novel therapeutic targets and provide information for further identification of other targets of therapeutic significance in gastric cancer.

Fluvastatin inhibits advanced glycation end products-induced proliferation, migration, and extracellular matrix accumulation in vascular smooth muscle cells by targeting connective tissue growth factor.

Connective tissue growth factor (CTGF) is a novel fibrotic mediator, which is considered to mediate fibrosis through extracellular matrix (ECM) synthesis in diabetic cardiovascular complications. Statins have significant immunomodulatory effects and reduce vascular injury. We therefore examined whether fluvastatin has anti-fibrotic effects in vascular smooth muscle cells (VSMCs) and elucidated its putative transduction signals. We show that advanced glycation end products (AGEs) stimulated CTGF mRNA and protein expression in a time-dependent manner. AGE-induced CTGF expression was mediated via ERK1/2, JNK, and Egr-1 pathways, but not p38; consequently, cell proliferation and migration and ECM accumulation were regulated by CTGF signaling pathway. AGE-stimulated VSMC proliferation, migration, and ECM accumulation were blocked by fluvastatin. However, the inhibitory effect of fluvastatin was restored by administration of CTGF recombinant protein. AGE-induced VSMC proliferation was dependent on cell cycle arrest, thereby increasing G1/G0 phase. Fluvastatin repressed cell cycle regulatory genes cyclin D1 and Cdk4 and augmented cyclin-dependent kinase inhibitors p27 and p21 in AGE-induced VSMCs. Taken together, fluvastatin suppressed AGE-induced VSMC proliferation, migration, and ECM accumulation by targeting CTGF signaling mechanism. These findings might be evidence for CTGF as a potential therapeutic target in diabetic vasculature complication.

Egr-1 mediates leptin-induced PPARγ reduction and proliferation of pulmonary artery smooth muscle cells.

Loss of peroxisome proliferator-activated receptor γ (PPARγ) has been found to contribute to pulmonary artery smooth muscle cell (PASMC) proliferation and pulmonary arterial remodeling therefore the development of pulmonary hypertension (PH). Yet, the molecular mechanisms underlying PPARγ reduction in PASMC remain poorly understood. Here, we demonstrated that leptin dose- and time-dependently inducued PPARγ down-regulation and proliferation of primary cultured rat PASMC, this was accompanied with the activation of extracellular regulated kinase1/2 (ERK1/2) signaling pathway and subsequent induction of early growth response-1 (Egr-1) expression. The presence of MEK inhibitors U0126 or PD98059, or prior silencing Egr-1 with small interfering RNA suppressed leptin-induced PPARγ reduction. In addition, activation of PPARγ by pioglitazone or targeting ERK1/2/Egr-1 suppressed leptin-induced PASMC proliferation. Taken together, our study indicates that ERK1/2 signaling pathway-mediated leptin-induced PPARγ reduction and PASMC proliferation through up-regulation of Egr-1 and suggests that targeting leptin/ERK1/2/Egr-1 pathway might have potential value in ameliorating vascular remodeling and benefit PH.

The p16/miR-217/EGR1 pathway modulates age-related tenogenic differentiation in tendon stem/progenitor cells.

Previous studies have shown that the differentiation potential declines with the age of progenitor cells and is linked to altered levels of senescence markers. The purpose of this study was to test whether senescence marker p16 affects age-related tenogenic differentiation in tendon stem/progenitor cells (TSPCs). Young and aged TSPCs were isolated from young/healthy and aged/degenerated human Achilles tendons, respectively. Cellular aging and capacity for tenogenic differentiation were examined. The results showed that the tenogenic differentiation capacity of TSPCs significantly decreases with advancing age. TSPCs from elderly donors showed upregulation of senescence-associated β-galactosidase and p16 and concurrently a decrease in Type I collagen concentration and in the expressions of tendon-related markers: Scx, Tnmd, Bgn, Dcn, Col1, and Col3. Overexpression of p16 significantly inhibited tenogenic differentiation of young TSPCs. Analysis of the mechanism revealed that this effect is mediated by microRNA-217 and its target EGR1. These results indicated that p16 inhibits tenogenic differentiation of TSPCs via microRNA signaling pathways, which may serve as a potential target for the prevention or treatment in the future.

Cigarette smoke extract induces placental growth factor release from human bronchial epithelial cells via ROS/MAPK (ERK-1/2)/Egr-1 axis.

Etiological evidence demonstrates that there is a significant association between cigarette smoking and chronic airway inflammatory disease. Abnormal expression of placental growth factor (PlGF) has been reported in COPD, and its downstream signaling molecules have been reported to contribute to the pathogenesis of airway epithelial cell apoptosis and emphysema. However, the signaling mechanisms underlying cigarette smoke extract (CSE)-induced PlGF expression in airway microenvironment remain unclear. Herein, we investigated the effects of reactive oxygen species (ROS)-dependent activation of the mitogen-activated protein kinase (MAPK) (extracellular signal-regulated kinase1/2 [ERK-1/2])/early growth response-1 (Egr-1) pathway on CSE-induced PlGF upregulation in human bronchial epithelium (HBE). The data obtained with quantitative reverse transcription polymerase chain reaction, Western blot, enzyme-linked immunosorbent assay (ELISA) and immunofluorescence staining analyses showed that CSE-induced Egr-1 activation was mainly mediated through production of ROS and activation of the MAPK (ERK-1/2) cascade. The binding of Egr-1 to the PlGF promoter was corroborated by an ELISA-based DNA binding activity assay. These results demonstrate that ROS activation of the MAPK (ERK-1/2)/Egr-1 pathway is a main player in the regulatory mechanism for CSE-induced PlGF production and that the use of an antioxidant could partly abolish these effects. Understanding the mechanisms of PlGF upregulation by CSE in the airway microenvironment may provide rational therapeutic interventions for cigarette smoking-related airway inflammatory diseases.

Activation of Tax protein by c-Jun-N-terminal kinase is not dependent on the presence or absence of the early growth response-1 gene product.

The Tax protein of human T cell leukemia virus type 1 plays a major role in the pathogenesis of adult T cell leukemia (ATL), an aggressive neoplasia of CD4+ T cells. In the present study, we investigated whether the EGR-1 pathway is involved in the regulation of Tax-induced JNK expression in human Jurkat T cells transfected to express the Tax protein in the presence or absence of PMA or ionomycin. Overexpression of EGR-1 in Jurkat cells transfected to express Tax, promoted the activation of several genes, with the most potent being those that contained AP-1 (Jun/c-Fos), whereas knockdown of endogenous EGR-1 by small interfering RNA (siRNA) somewhat reduced Tax-mediated JNK-1 transcription. Additionally, luciferase-based AP-1 and NF-κB reporter gene assays demonstrated that inhibition of EGR-1 expression by an siRNA did not affect the transcriptional activity of a consensus sequence of either AP-1 or NF-κB. On the other hand, the apoptosis assay, using all-trans retinoic acid (ATRA) as an inducer of apoptosis, confirmed that siRNA against EGR-1 failed to suppress ATRA-induced apoptosis in Jurkat and Jurkat-Tax cells, as noted by the low levels of both DEVDase activity and DNA fragmentation, indicating that the induction of apoptosis by ATRA was Egr-1-independent. Finally, our data showed that activation of Tax by JNK-1 was not dependent on the EGR-1 cascade of events, suggesting that EGR-1 is important but not a determinant for the activity for Tax-induced proliferation of Jurkat cells.

Evaluation of genes involved in the JAK/EGFR/ERK/EGR-1 pathway for their mRNA expression in pregnant and non-pregnant equine endometrium during the time of maternal recognition of pregnancy

Evaluation of genes involved in the JAK/EGFR/ERK/EGR-1 pathway for their mRNA expression in pregnant and non-pregnant equine endometrium during the time of maternal recognition of pregnancy

Occupational Styrene Exposure Induces Stress-Responsive Genes Involved in Cytoprotective and Cytotoxic Activities

ObjectiveThe aim of this study was to evaluate the expression of a panel of genes involved in toxicology in response to styrene exposure at levels below the occupational standard setting.MethodsWorkers in a fiber glass boat industry were evaluated for a panel of stress- and toxicity-related genes and associated with biochemical parameters related to hepatic injury. Urinary styrene metabolites (MA+PGA) of subjects and environmental sampling data collected for air at workplace were used to estimate styrene exposure.ResultsExpression array analysis revealed massive upregulation of genes encoding stress-responsive proteins (HSPA1L, EGR1, IL-6, IL-1β, TNSF10 and TNFα) in the styrene-exposed group; the levels of cytokines released were further confirmed in serum. The exposed workers were then stratified by styrene exposure levels. EGR1 gene upregulation paralleled the expression and transcriptional protein levels of IL-6, TNSF10 and TNFα in styrene exposed workers, even at low level. The activation of the EGR1 pathway observed at low-styrene exposure was associated with a slight increase of hepatic markers found in highly exposed subjects, even though they were within normal range. The ALT and AST levels were not affected by alcohol consumption, and positively correlated with urinary styrene metabolites as evaluated by multiple regression analysis.ConclusionThe pro-inflammatory cytokines IL-6 and TNFα are the primary mediators of processes involved in the hepatic injury response and regeneration. Here, we show that styrene induced stress responsive genes involved in cytoprotection and cytotoxicity at low-exposure, that proceed to a mild subclinical hepatic toxicity at high-styrene exposure.

Activation of Egr-1 in Human Lung Epithelial Cells Exposed to Silica through MAPKs Signaling Pathways

The alveolar type II epithelial cell, regarded historically as a key target cell in initial injury by silica, now appears to be important in both defense from lung damage as well as elaboration of chemokines and cytokines. The molecular basis for silica-induced epithelial cell injury is poorly understood. In this study we explored the activation of nuclear factor Egr-1 and related signal pathway. Human II alveolar epithelial line A549 cells were exposed to silica for indicated time to assay the expression and activation of Egr-1 and upstream MAPKs. Immunofluorescence, western-blot techniques, RT-PCR, Electrophoretic mobility shift assay (EMSA), transient transfection assay, kinase inhibitor experiments were performed. It was found that the expression of Egr-1 at mRNA and protein level was significantly increased in A549 cells after administration with silica and the activity of Egr-1 peaked by silica treatment for 60 minutes. Furthermore, phosphorylated-ERK1/2, P38 MAPKs (the upstream kinase of Egr-1) ballooned during 15-30minutes, 30-60minutes respectively after silica exposure in A549 cells. By administration of ERK1/2, P38 inhibitor, the expression and transcription of Egr-1 were both markedly decreased. But PKC inhibitor did not prevent the increase of Egr-1. These results indicated Egr-1 played a critical role in silica-induced pulmonary fibrosis in an ERK1/2, P38 MAPKs-dependent manner, which suggests Egr-1 is an essential regulator in silicosis, and underlines a new molecular mechanism for fibrosis induced by silica.

Melatonin attenuates scopolamine-induced memory/synaptic disorder by rescuing EPACs/miR-124/Egr1 pathway

Melatonin attenuates scopolamine-induced memory/synaptic disorder by rescuing EPACs/miR-124/Egr1 pathway