Expression Of Early Growth Response Protein Research Articles

Oxidative stress-induced EGR1 upregulation promotes NR4A3-mediated nucleus pulposus cells apoptosis in intervertebral disc degeneration.

This study aimed to reveal the specific role of early growth response protein 1 (EGR1) and nuclear receptor 4A3 (NR4A3) in nucleus pulposus cells (NPCs) and the related molecular mechanism and to identify a new strategy for treating intervertebral disc degeneration (IVDD). Bioinformatics analysis was used to explore and predict IVDD-related differentially expressed genes, and chromatin immunoprecipitation sequencing (ChIP-seq) revealed NR4A3 as the EGR1 target gene. An in vitro NPC model induced by tributyl hydrogen peroxide (TBHP) and a rat model induced by fibrous ring acupuncture were established. Western blotting, quantitative real-time polymerase chain reaction (qRT-PCR), immunohistochemical staining, immunofluorescence staining, and flow cytometry were used to detect the effects of EGR1 and NR4A3 knockdown and overexpression on NPC apoptosis and the expression of extracellular matrix (ECM) anabolism-related proteins. Interactions between EGR1 and NR4A3 were analyzed via ChIP-qPCR and dual luciferase assays. EGR1 and NR4A3 expression levels were significantly higher in severely degenerated discs (SDD) than in mildly degenerated discs (MDD), indicating that these genes are important risk factors in IVDD progression. ChIP-seq and RNA-seq revealed NR4A3 as a direct downstream target of EGR1, and this finding was verified by ChIP-qPCR and dual luciferase reporter experiments. Remarkably, the rescue experiments showed that EGR1 promotes TBHP-induced NPC apoptosis and impairs ECM anabolism, dependent on elevated NR4A3 expression. In summary, the EGR1-NR4A3 axis mediates the progression of NPC apoptosis and ECM impairment and is a potential therapeutic target in IVDD.

Iguratimod suppresses sclerostin and receptor activator of NF-κB ligand production via the extracellular signal–regulated kinase/early growth response protein 1/tumor necrosis factor alpha pathway in osteocytes and ameliorates disuse osteoporosis in mice

Disuse osteoporosis is a prevalent complication among patients afflicted with rheumatoid arthritis (RA). Although reports have shown that the antirheumatic drug iguratimod (IGU) ameliorates osteoporosis in RA patients, details regarding its effects on osteocytes remain unclear. The current study examined the effects of IGU on osteocytes using a mouse model of disuse-induced osteoporosis, the pathology of which crucially involves osteocytes. A reduction in distal femur bone mass was achieved after 3 weeks of hindlimb unloading in mice, which was subsequently reversed by intraperitoneal IGU treatment (30 mg/kg; five times per week). Histology revealed that hindlimb-unloaded (HLU) mice had significantly increased osteoclast number and sclerostin-positive osteocyte rates, which were suppressed by IGU treatment. Moreover, HLU mice exhibited a significant decrease in osteocalcin-positive cells, which was attenuated by IGU treatment. In vitro, IGU suppressed the gene expression of receptor activator of NF-κB ligand (RANKL) and sclerostin in MLO-Y4 and Saos-2 cells, which inhibited osteoclast differentiation of mouse bone marrow cells in cocultures. Although IGU did not affect the nuclear translocation or transcriptional activity of NF-κB, RNA sequencing revealed that IGU downregulated the expression of early growth response protein 1 (EGR1) in osteocytes. HLU mice showed significantly increased EGR1- and tumor necrosis factor alpha (TNFα)-positive osteocyte rates, which were decreased by IGU treatment. EGR1 overexpression enhanced the gene expression of TNFα, RANKL, and sclerostin in osteocytes, which was suppressed by IGU. Contrarily, small interfering RNA-mediated suppression of EGR1 downregulated RANKL and sclerostin gene expression. These findings indicate that IGU inhibits the expression of EGR1, which may downregulate TNFα and consequently RANKL and sclerostin in osteocytes. These mechanisms suggest that IGU could potentially be used as a treatment option for disuse osteoporosis by targeting osteocytes.

EGR1 Promotes Ovarian Hyperstimulation Syndrome Through Upregulation of SOX9 Expression.

Angiogenesis is strongly associated with ovarian hyperstimulation syndrome (OHSS) progression. Early growth response protein 1 (EGR1) plays an important role in angiogenesis. This study aimed to investigate the function and mechanism of EGR1 involved in OHSS progression. RNA-sequencing was used to identify differentially expressed genes. In vitro OHSS cell model was induced by treating KGN cells with human chorionic gonadotropin (hCG). In vivo OHSS model was established in mice. The expression levels of EGR1, SOX1, and VEGF were determined by Quantitative Real-Time polymerase chain reaction (qRT-PCR), Western blot, immunofluorescence staining, and immunochemistry assay. The content of VEGF in the culture medium of human granulosa-like tumor cell line (KGN) cells was accessed by the ELISA assay. The regulatory effect of EGR1 on SRY-box transcription factor 9 (SOX9) was addressed by luciferase reporter assay and chromatin immunoprecipitation. The ERG1 and SOX9 levels were significantly upregulated in granulosa cells from OHSS patients and there was a positive association between EGR1 and SOX9 expression. In the ovarian tissues of OHSS mice, the levels of EGR1 and SOX9 were also remarkedly increased. Treatment with hCG elevated the levels of vascular endothelial growth factor (VEGF), EGR1, and SOX9 in KGN cells. Silencing of EGR1 reversed the promoting effect of hCG on VEGF and SOX9 expression in KGN cells. EGR1 transcriptionally regulated SOX9 expression through binding to its promoter. In addition, administration of dopamine decreased hCG-induced VEGF in KGN cells and ameliorated the progression of OHSS in mice, which were companied with decreased EGR1 and SOX9 expression. EGR1 has a promoting effect on OHSS progression and dopamine protects against OHSS through suppression of EGR1/SOX9 cascade. Our findings may provide new targets for the treatment of OHSS.

Tetrahydroxylated bile acids improve cholestatic liver and bile duct injury in the Mdr2-/- mouse model of sclerosing cholangitis via immunomodulatory effects.

Bile salt export pump (Bsep) (Abcb11) −/− mice are protected from acquired cholestatic injury due to metabolic preconditioning with a hydrophilic bile acid (BA) pool with formation of tetrahydroxylated bile acids (THBAs). We aimed to explore whether loss of Bsep and subsequent elevation of THBA levels may have immunomodulatory effects, thus improving liver injury in the multidrug resistance protein 2 (Mdr2) (Abcb4) −/− mouse. Cholestatic liver injury in Mdr2 −/− Bsep −/− double knockout (DKO), Mdr2 −/− , Bsep −/− , and wild‐type mice was studied for comparison. Mdr2 −/− mice were treated with a THBA (3α,6α,7α,12α‐Tetrahydroxycholanoic acid). RNA/protein expression of inflammatory/fibrotic markers were investigated. Serum BA‐profiling was assessed by ultra‐performance liquid chromatography tandem mass spectrometry. Hepatic immune cell profile was quantified by flow cytometric analysis (FACS). In vitro, the THBA effect on chenodeoxycholic acid (CDCA)–induced inflammatory signaling in hepatocyte and cholangiocytes as well as lipopolysaccharide (LPS)/interferon‐γ (IFN‐γ)–induced macrophage activation was analyzed. In contrast to Mdr2 −/− , DKO mice showed no features of sclerosing cholangitis. Sixty‐seven percent of serum BAs in DKO mice were polyhydroxylated (mostly THBAs), whereas Mdr2 −/− mice did not have these BAs. Compared with Mdr2 −/−, DKO animals were protected from hepatic inflammation/fibrosis. THBA feeding in Mdr2 −/− mice improved liver injury. FACS analysis in DKO and Mdr2 −/− THBA‐fed mice showed changes of the hepatic immune cell profile towards an anti‐inflammatory pattern. Early growth response 1 (EGR1) protein expression was reduced in DKO and in Mdr2 −/− THBA‐fed mice compared with Mdr2 −/− control mice. In vitro, THBA‐reduced CDCA induced EGR1 protein and mRNA expression of inflammatory markers in hepatocytes and cholangiocytes. LPS/IFN‐γ–induced macrophage activation was ameliorated by THBA. THBAs repress EGR1‐related key pro‐inflammatory pathways. Conclusion: THBA and their downstream targets may represent a potential treatment strategy for cholestatic liver diseases.

Reduced expression of neurogenesis genes as biomarkers of Parkinson's disease associated with mutations in the <i>GBA</i> gene: validation of the data analysis of transcriptome study

The objective of the study was to validate our previous results obtained during the transcriptome analysis of the primary culture of peripheral blood macrophages in patients with Parkinson's disease associated with mutations in the GBA gene (GBA-PD) in that reduced expression of the neurogenesis genes EGR1 (early growth response protein 1), NR4A2 (nuclear receptor 4A2), JUNB (transcription factor jun-B) in patients with GBA-PD.Methods and materials. The study included 14 patients with GBA-PD, 15 GBA-carriers, 30 patients with Parkinson's disease (PD) and 44 persons of the control group. The assessment of relative mRNA level of neurogenesis genes EGR1, NR4A2, JUNB in peripheral blood mononuclear cells were carried out by real-time quantitative polymerase chain reaction (PCR) using TaqMan fluorescent probes or EvaGreen fluorescent DNA dye.Results. Relative mRNA level of the JUNB gene in peripheral blood mononuclears was decreased in the group of patients with GBA-PD compared to controls (p=0.034). We found out that the relative mRNA level of the NR4A2 gene in peripheral blood mononuclears was increased in the group of patients with GBA-carriers compared to GBA-PD, patients with PD and controls (p=0.0029, p=0.00045, p=0.0024 respectively). There were no statistically significant differences in the mRNA level of the EGR1 gene between all the study groups (p>0.05).Conclusion. GBA-PD is characterized by reduced expression of the JUNB gene compared to control and of the NR4A2 gene compared to GBA-carriers.

GPR43 activation-mediated lipotoxicity contributes to podocyte injury in diabetic nephropathy by modulating the ERK/EGR1 pathway.

Background: G-protein-coupled receptor 43 (GPR43) is a posttranscriptional regulator involved in cholesterol metabolism. This study aimed to investigate the possible roles of GPR43 activation in podocyte lipotoxicity in diabetic nephropathy (DN) and explore the potential mechanisms.Methods: The experiments were conducted by using diabetic GPR43-knockout mice and a podocyte cell culture model. Lipid deposition and free cholesterol levels in kidney tissues were measured by BODIPY staining and quantitative cholesterol assays, respectively. The protein expression of GPR43, LC3II, p62, beclin1, low-density lipoprotein receptor (LDLR) and early growth response protein 1 (EGR1) in kidney tissues and podocytes was measured by real-time PCR, immunofluorescent staining and Western blotting.Results: There were increased LDL cholesterol levels in plasma and cholesterol accumulation in the kidneys of diabetic mice. However, GPR43 gene knockout inhibited these changes. An in vitro study further demonstrated that acetate treatment induced cholesterol accumulation in high glucose-stimulated podocytes, which was correlated with increased cholesterol uptake mediated by LDLR and reduced cholesterol autophagic degradation, as characterized by the inhibition of LC3 maturation, p62 degradation and autophagosome formation. Gene knockdown or pharmacological inhibition of GPR43 prevented these effects on podocytes. Furthermore, GPR43 activation increased extracellular regulated protein kinases 1/2 (ERK1/2) activity and EGR1 expression in podocytes, which resulted in an increase in cholesterol influx and autophagy inhibition. In contrast, after GPR43 deletion, these changes in podocytes were improved, as shown by the in vivo and in vitro results.Conclusion: GPR43 activation-mediated lipotoxicity contributes to podocyte injury in DN by modulating the ERK/EGR1 pathway.

Competing endogenous RNA network associated with oxygen-induced retinopathy: Expression of the network and identification of the MALAT1/miR-124–3p/EGR1 regulatory axis

Retinopathy of prematurity (ROP) is a severe retinal dysfunction in prematurely born babies. The relationship between non-coding RNAs and retinopathy of prematurity (ROP) remain unclear. Microarray analysis of lncRNAs, miRNAs, and mRNAs was conducted in a mouse model of ROP. A competing endogenous RNA (ceRNA) network was constructed. The relationship among MALAT1, miR-124–3p, and Early growth response protein 1 (EGR1) was assessed in hypoxia-induced primary human umbilical vein endothelial cells (HUVECs) and ROP mouse model. In the study, we found 2252 lncRNAs, 1239 mRNAs, and 36 miRNAs were differentially regulated. ceRNA network consisting of 21 lncRNAs, 10 miRNAs, and 19 mRNAs was established. Of the most down-regulated miRNAs, miR-124–3p was selected for additional study. miR-124–3p ceased the migration and proliferation of primary HUVECs in hypoxic conditions, and directly suppressed EGR1. Additionally, MALAT1 directly sponged miR-124–3p. Knockdown of MALAT1 decreased EGR1 expression and inhibited the migration and proliferation of primary HUVECs in hypoxia. Furthermore, these changes were rescued by depletion of miR-124–3p. In vivo, intravitreal injection of miR-124–3p, shMALAT1 decreased EGR1 expression and markedly suppressed retinal neovascularization in OIR models. Intravitreal injection of shMALAT1 and miR-124–3p antagomir at the same time can promote retinal neovascularization, which reversed the suppression of retinal neovascularization functioned by shMALAT1. In conclusion, the expression profiles of lncRNAs and miRNAs and the ceRNA network in a mouse model of ROP may be indicative of the underlying mechanisms of retinal angiogenesis and neural activity. The MALAT1/miR-124–3p/EGR1 regulatory axis is partly responsible for retinal neovascularization, which may provide a novel theoretical basis for the pathogenesis of ROP.

PFOA Exposure Prior to Hepatocyte Differentiation Leads to Gene Expression Changes Implicated in Non-Alcoholic Fatty Liver Disease

Background: Perfluorooctanoic acid (PFOA), is a persistent fluorinated compound with oil and water repelling properties found in cookware, food packaging and municipal water systems. Adult animals exposed to PFOA develop hepatomegaly, fatty liver, peroxisome proliferation, and immunotoxicity. Rodents exposed to PFCs in utero have altered hepatic lipid metabolism, increased hepatic de novo lipogenesis and susceptibility to non-alcoholic fatty liver disease (NAFLD), but underlying molecular mechanisms remain unknown. With increasing rates of obesity, diabetes, and NAFLD it is critical to examine the mechanisms by which in utero exposure to PFOA contributes to the development of metabolic syndrome in offspring. Objective: To determine mechanism by which PFOA alters gene expression in undifferentiated hepatic progenitor cells. Design/methods: HepaRG cells, a human derived hepatocyte progenitor cell line, was treated with 0.5uM PFOA or vehicle for 48 hours followed by differentiation into hepatocytes. Total RNA was extracted using the RNeasy (Qiagen) [total RNA A260/280>2 and RNA integrity number >7 (Agilent Bioanalyzer)] to generate libraries with the Illumina TruSeq stranded total RNA kit. RNA-Seq was performed using 85 bp single-end read sequencing to generate >20 million reads per sample. RNAseq data was aligned to hg38 using STAR v2.6.1a and then quantified with featureCounts v1.6.2. DESeq2 identified differentially expressed genes via FDR (false discovery rate) after Bonferroni correction. Differentially expressed gene lists were used for Ingenuity Pathway Analysis (IPA) to identify pathways of biological significance.Results: PFOA treatment resulted in increased expression of transcription factors EGR1 (early growth response protein 1), NR4A1 (nuclear receptor Nur77), EGR2 (early growth response protein 2), KLF10 (Krueppel-like factor 10) and FOSL1 (Fos-related antigen 1), key genes linked to impaired hepatic insulin signaling, hepatic lipid metabolism, steatosis and fibrosis (fold change > 1.5; q <0.05). IPA identified enrichment of canonical pathways with biological relevance including hepatic fibrosis signaling, stellate cell activation, VDR/RXR/TR activation, and Type 2 diabetes mellitus signaling (p<0.01). Conclusion: Hepatocyte progenitor cells exposed to low dose PFOA for 48 hours prior to differentiation results in changes in expression of key metabolic genes linked to the development of NAFLD and enrichment of biologically relevant pathways associated with hepatic fibrosis and hepatocellular carcinoma. These results suggest that PFOA exposure in utero may have lasting effects on hepatic glucose and lipid metabolism after differentiation. Further studies are needed to characterize the longstanding metabolic effects of in utero PFOA exposure in offspring and the mechanisms driving the persistence of these changes.

Early Growth Response Protein 1 Knockdown Alleviates the Cerebral Injury in Rats with Intracerebral Hemorrhage via STAT3/NF-κB Pathway by Reducing RXRα Acetylation Level

Brain EGR1 (early growth response protein 1) overexpression aggravates focal ischemic brain injury, but its role in intracerebral hemorrhage (ICH) induced cerebral injury remains obscure. In this study, a rat ICH model was established by injecting type VII collagenase into the brain, and EGR1 knockdown reversed the increase of hematoma area, neurological function score, brain water content, blood–brain barrier (BBB) permeability, inflammation, p300 and retinoid a X receptor-α (RXRα) protein levels, as well as RXRα acetylation level induced by ICH. EGR1 expression was up-regulated in primary brain microvascular endothelial cells (BMECs), neurons, and astrocytes after ICH induction, and the up-regulation was most significant in BMECs. We also found that EGR1 promoted RXRα acetylation level by regulating p300 in BMECs. Silencing EGR1 rescued the upregulation of cell inflammation and the reduction of cell viability and TEER (transendothelial electric resistance) caused by OGD (oxygen glucose deprivation) plus hemin via p300-mediated RXRα acetylation. Furthermore, the STAT3/NF-κB pathway was activated after treatment with OGD plus hemin, which was suppressed by silencing EGR1. Treatment with Stattic (an inhibitor of STAT3) restrained the effect of OGD plus hemin on NF-κB pathway activity, inflammation, cell viability and TEER. In conclusion, EGR1 increased RXRα acetylation level by regulating p300, thereby aggravating brain damage in ICH rat model and dysfunction in BMECs, Through the STAT3/NF-κB pathway.

Weighted gene coexpression network reveals downregulation of genes in bronchopulmonary dysplasia.

Bronchopulmonary dysplasia (BPD) is a serious lung disease observed in premature infants, known to cause considerable morbidity and mortality. Its prognosis is influenced by a complex network of genetic interactions. In this study, we determined the potential key factors in the pathogenesis of this condition. We constructed scale-free gene coexpression network using weighted gene coexpression network analysis. The analysis was carried out on the GSE8586 dataset, which contains the expression profiles of umbilical cord tissue homogenates from 20 neonates with BPD and 34 unaffected controls. Our analysis identified one significantly downregulated coexpression module related to the BPD phenotype. It was significantly enriched in genes related to human T-cell leukemia virus infection and the mitogen-activated protein kinase pathway. In this module, the expression of the following four hub genes in infants with BPD was significantly decreased: Fos proto-oncogene (FOS), BTG antiproliferation factor 2 (BTG2), Jun proto-oncogene (JUN), and early growth response protein 1 (EGR1). The downregulation of these hub genes was verified in clinical samples derived from blood and umbilical cord tissue. The decreased expression of FOS, BTG2, JUN, and EGR1 is associated with BPD and, therefore, could be used as biomarkers to diagnose early BPD.

MicroRNA-217 ameliorates inflammatory damage of endothelial cells induced by oxidized LDL by targeting EGR1.

Oxidized low-density lipoprotein (ox-LDL) modulates gene transcription and expression and induces the development of endothelium inflammation and endothelial dysfunction, in which microRNAs (miRNAs) play a crucial role. However, the mechanism of ox-LDL in inflammatory damage of endothelial cells still remains elusive. Herein, we focused on the effect of hsa-miR-217-5p (miR-217) on endothelial dysfunction induced by ox-LDL by targeting early growth response protein-1 (EGR1). In the present study, 31 upregulated miRNAs and 59 downregulated miRNAs (Fold Change > 2, P value < 0.05) were identified after 6h of 80μg/mL ox-LDL exposure in human aortic endothelial cells (HAECs) by small RNA sequencing, including miR-217 that was significantly decreased (FC = 0.2787, P value = 5.22E-16). MiR-217 knockdown inhibited cell proliferation and increased level of IL-6, IL-1β, ICAM-1 and TNF-α, while overexpression of miR-217 relieved the growth inhibition induced by ox-LDL and demonstrated anti-inflammatory effect in HAECs. EGR1 was predicted as a potential candidate target gene of miR-217 by TargetScan. The subsequent dual-luciferase reporter assay confirmed the direct binding of miR-217 to 3'UTR of EGR1. And EGR1 expression was negatively correlated with the level of miRNA-217 in HAECs after exposure to ox-LDL. Overexpression of EGR1 recapitulated the effects of miR-217 knockdown on cell proliferation inhibition and inflammation in HAECs, while knockdown EGR1 relieved the proliferative inhibition and demonstrated anti-inflammatory effect in ox-LDL-induced HAECs. The present study confirmed miR-217 ameliorates inflammatory damage of endothelial cells induced by oxidized LDL by targeting EGR1.

Transcription factor EGR-1 transactivates the MMP1 gene promoter in response to TNFα in HaCaT keratinocytes

Matrix metalloproteinase 1 (MMP-1), a calcium-dependent zinc- containing collagenase, is involved in the initial degradation of native fibrillar collagen. Tissue necrosis factor-alpha (TNFα) is a pro-inflammatory cytokine that is rapidly produced by dermal fibroblasts, monocytes/macrophages, and keratinocytes and regulates inflammation and damaged-tissue remodeling. MMP-1 is induced by TNFα and plays a critical role in tissue remodeling and skin aging processes. However, the regulation of the MMP1 gene by TNFα is not fully understood. We aimed to find additional cis-acting elements involved in the regulation of TNFα-induced MMP1 gene transcription in addition to the nuclear factor-kappa B (NF-kB) and activator protein 1 (AP1) sites. Assessments of the 5’-regulatory region of the MMP1 gene, using a series of deletion constructs, revealed the requirement of the early growth response protein 1 (EGR-1)-binding sequence (EBS) in the proximal region for proper transcription by TNFα. Ectopic expression of EGR-1, a zinc-finger transcription factor that binds to G-C rich sequences, stimulated MMP1 promoter activity. The silencing of EGR-1 by RNA interference reduced TNFα-induced MMP-1 expression. EGR-1 directly binds to the proximal region and transactivates the MMP1 gene promoter. Mutation of the EBS within the MMP1 promoter abolished EGR-1-mediated MMP-1 promoter activation. These data suggest that EGR-1 is required for TNFα-induced MMP1 transcriptional activation. In addition, we found that all three MAPKs, ERK1/2, JNK, and p38 kinase, mediate TNFα-induced MMP-1 expression via EGR-1 upregulation. These results suggest that EGR-1 may represent a good target for the development of pharmaceutical agents to reduce inflammation-induced MMP-1 expression.

Novel Tumor Suppressor PMM1 Suppresses Oral Cancer Growth through Activation Unfolding Protein Response Activator EGR1

Protein glycosylation is the common post‐translational modification in the mammalian cells. More than half proteins have their own glycosylation which increasing the protein diversity and complexity or maintaining protein stability. N‐glycosylation is a quality control marker of protein folding. Aberrant n‐glycosylation usually cause unfolding protein response and endoplasmic reticulum stress. Here, we find phosphomannomutase 1 (PMM1), which converts initiation molecule in n‐glycosylation to mannose‐1‐phosphate, serves as a tumor suppressor gene in oral squamous cell carcinoma (OSCC). PMM1 peptide sequence and enzymatic substrate are highly similar to PMM2. However, we found PMM1 might have an opposite cancer progression effect in public prognosis analysis. Ectopic wildtype PMM1 expression suppressed in vitro cancer cell proliferation, but not in the catalytic domain death PMM1‐R150H clone. Furthermore, wildtype PMM1 also suppressed the in vivo OSCC cell growth in the Nod‐SCID immunodeficient mice. Transcriptome analysis by cDNA microarray and ingenuity pathway analysis revealed that PMM1 stimulated early growth response protein 1 (EGR1) pathway activation. As we known, EGR1 is a tumor suppressor and the master activator in unfolding protein response. Our study suggests that PMM1 is a gatekeeper in cellular protein folding and OSCC tumor suppressor through regulating EGR1 expression. This study provides new insights into an important mechanism for n‐glycosylation and protein folding in oral carcinoma, which may be helpful for biomarker and therapeutic development in the future.

Soluble Klotho regulates bone differentiation by upregulating expression of the transcription factor EGR‐1

Klotho is a transmembrane protein known to regulate aging and lifespan. Soluble Klotho (sKL), a truncated form of Klotho, regulates various cell signaling pathways, including bone development. Here, we investigated the relationship between sKL and the zinc finger transcription factor early growth response protein 1 (EGR-1) on bone formation. We find that sKL induces the expression of EGR-1 mRNA and protein. Through mutational analysis, we identify the 130bp region on the EGR-1 promoter that is responsive to sKL overexpression. Additionally, sKL induces the expression of markers of bone differentiation (BMP2, RUNX2, ALP, COL1A, and osteocalcin) in osteoblast MC3T3 cells. EGR-1 siRNA decreases the bone mineralization induced by sKL or ascorbic acid/glycerol 2-phosphate in MC3T3 cells. Our results suggest that sKL may regulate bone development through EGR-1 expression.

Early growth response 1 reduction in peripheral blood involving condylar subchondral bone loss.

To detect whether early growth response 1 (EGR1) in peripheral blood leucocytes (PBLs) indicates temporomandibular joint (TMJ) osteoarthritis (OA) lesions. Egr1 mRNA expression levels in PBLs were detected in eight malocclusion patients without temporomandibular disorder (TMD) signs and 16 malocclusion patients with clinical TMD signs with (eight) or without (eight) imaging signs of TMJ OA. Twelve 6-week-old rats were randomized to a control group and a unilateral anterior crossbite (UAC) group and were sampled at 4weeks. The Egr1 mRNA expression levels in PBLs and protein expression levels in different orofacial tissues were measured. Patients with TMD signs with/without TMJ OA diagnosis showed lower Egr1 mRNA expression levels in PBLs than patients without TMD signs. The lower Egr1 mRNA expression was also found in the PBLs of UAC rats, which were induced to exhibit early histo-morphological signs of TMJ OA lesions. In subchondral bone of UAC rats, EGR1 protein expression was decreased, co-localization of EGR1 with osterix or dentin matrix protein-1 was identified, and the number of EGR1 and osterix double-positive cells was reduced (all p<.05). Egr1 reduction in PBLs potentially indicates subchondral bone OA lesions at an early stage.

MicroRNA-34a suppresses the invasion and migration of colorectal cancer cells by enhancing EGR1 and inhibiting vimentin.

MicroRNAs (miRNAs/miRs) are small non-coding RNAs that serve a post-transcriptional regulatory role in eukaryotes. Previous studies have demonstrated that the expression of miR-34a in colorectal cancer (CRC) tissues is decreased compared with that in normal colorectal tissues. However, the role of miR-34a in the invasion and metastasis of CRC remains unclear. In the present study, the levels of miR-34a expression were measured in various CRC cell lines. The cells were transfected with miR-34a mimics or inhibitors in order to assess the proliferation rate, and the colony forming, invasive and migratory abilities. Furthermore, the protein expression levels of vimentin and early growth response protein 1 (EGR1) were examined by western blot analysis. The results revealed that the expression of miR-34a was low in SW620, RKO, LoVo and Caco-2 cell lines and high in the SW480 and SW1116 cell lines. The migration, invasion and proliferation levels of SW480 cells were facilitated by decreasing the expression of miR-34a. Transient transfection with miR-34a mimics in SW620 cells caused a notable decrease in cell migration, invasion and proliferation levels compared with the control group, and a downregulation of vimentin and upregulation of EGR1 protein expression. The present study demonstrated that miR-34a was deregulated in a highly invasive CRC cell lines, and that it may attenuate the migratory, invasive and proliferative capabilities of CRC cells by enhancing the expression of EGR1 and inhibiting that of vimentin. The results of the present study represent important progress towards understanding the mechanisms of CRC recurrence and metastasis.

Increased miRNA-518b inhibits trophoblast migration and angiogenesis by targeting EGR1 in early embryonic arrest†.

Evidence indicates that microRNAs (miRNAs) play essential roles in early embryonic development. The miRNA-518 family is a special biomarker of the placenta, and miRNA-518b is abnormally expressed in placental tissue in preeclampsia. Early growth response protein 1 (EGR1), a zinc finger transcriptional factor, plays an essential role in regulating cell differentiation, angiogenesis, and migration. Moreover, earlier studies have shown that EGR1 protein plays a key role in implantation. However, little is known about the role of miR-518b and EGR1 on early embryonic arrest (EEA) in humans. In our study, increased miR-518b along with decreased EGR1 was found in human villus tissues with EEA. Furthermore, we demonstrated by luciferase assay that miR-518b is a direct regulator of EGR1. After comparing the effect of silencing EGR1, vascular endothelial growth factor (VEGF) individually, and EGR1/VEGF in combination, we found that EGR1 can inhibit migration and angiogenesis of HTR-8 SVneo cells by decreasing the VEGF expression. Hypoxia plays an initial role in early embryonic development, and we found that hypoxia reduces the expression of miR-518b and increases the expression of EGR1 and VEGF to facilitate migration and angiogenesis in a hypoxic model of HTR-8/SVneo cell line. Our findings provide new insights into the role of miR-518b in EEA and implicate the potential application of miR-518b in the diagnosis and development of intervention for EEA.

EGR1 IS NEGATIVELY ASSOCIATED WITH HNSCC CELL INVASION VIA INHIBITION OF MMP9 AND MDM2

Objectives The effect of early growth response-1 (EGR1) on cancer invasion remains controversial depending on the cancer type. EGR1 is known to slow the progression of cancer by inhibiting the expression of MMP2. However, the effect of EGR1 on MMP9, which is important for HNSCC invasion, is disputed. Our aim is to clarify the tumor suppressor role of EGR1 in downregulating MMP9. We also consider MDM2, an enhancer of MMP9 expression. Findings EGR1 mRNA and protein expression were compared in normal and HNSCC tissues using The Cancer Genome Atlas (TCGA) dataset analysis as well as immunohistochemistry (IHC). In vitro cell invasion was performed by two-dimension (2-D) and three-dimension (3-D) spheroids Matrigel invasion assay. TCGA data showed significantly higher EGR1 mRNA levels in nonmetastatic HNSCC tissues than in metastatic tissues. IHC analysis showed significantly higher levels of nuclear EGR1 expression in primary tumor tissues than in paired metastatic lymph node tissues. Transient EGR1 overexpression inhibited the Matrigel invasion of HNSCC cells, as well as decreasing mRNA of MMP9 and MDM2. Consistent with these observations, TCGA data analysis found significantly fewer metastatic patients among a subgroup of a large population presenting higher EGR1 expressions with lower MMP9 and/or MDM2. Conclusions Our data suggests that EGR1 might be a potential candidate to attenuate HNSCC metastasis.

Involvement of the Akt-dependent CREB signaling pathway in hydrogen-peroxide-induced early growth response protein-1 expression in rat vascular smooth muscle cells 1.

Increased generation of reactive oxygen species is believed to play a key role in the pathophysiology of cardiovascular diseases. Excessive growth and proliferation of vascular smooth muscle cells (VSMCs) have been suggested to be major contributors to vascular dysfunction. Potential involvement of early growth response protein-1 (Egr-1), a zinc finger transcription factor, in the development of vascular diseases has been suggested. Recent studies have shown that the reactive oxygen species hydrogen peroxide (H2O2) increases Egr-1 expression in VSMCs; however, signaling events leading to H2O2-induced Egr-1 expression are not fully understood. Therefore, we aimed to determine the signaling pathways implicated in H2O2-induced Egr-1 expression in rat VSMCs. Pharmacological blockade of the phosphatidylinositol 3-kinase/Akt pathway by wortmannin or SC66 significantly inhibited the protein and mRNA levels of Egr-1 induced by H2O2. H2O2-induced Egr-1 expression was associated with increased phosphorylation of cyclic AMP response element-binding (CREB) protein, and pharmacological inhibition or silencing of Akt attenuated both H2O2-induced CREB phosphorylation and Egr-1 expression. Moreover, RNA interference-mediated depletion of CREB almost completely suppressed the stimulatory effect of H2O2 on Egr-1 expression. Pharmacological blockade or silencing of c-Src resulted in significant suppression of H2O2-induced Egr-1 expression as well as Akt and CREB phosphorylation. These data show that H2O2 enhances the expression of Egr-1, which was associated with increased phosphorylation of Akt, and H2O2 triggers its effects on Egr-1 expression through c-Src-mediated Akt and CREB-dependent signaling events in VSMCs.

A negative feedback loop of H19/miR-675/EGR1 is involved in diabetic nephropathy by downregulating the expression of the vitamin D receptor.

We aimed to explore the regulatory relationship among the long noncoding RNA H19, micorRNA-675 (miR-675), the vitamin D (VD) receptor (VDR), and the early growth response protein 1 (EGR1)in the pathogenesis of diabetic nephropathy (DN) among patients with diabetes mellitus (DM). Expression levels of H19, miR-675, VDR, and EGR in patients or CIHP-1/HEK 293 cells were measured via quantitative reverse-transcription polymerase chain reaction and western blot analysis. Computational analysis and luciferase assays were performed to determine EGR1 as a target gene of miR-675. The relative expression of miR-675 was higher in the presence of H19, whereas the expression of both VDR and EGR1 messenger RNA was decreased in the presence of H19 or miR-675. However, relative expression of H19 and miR-675 was increased, whereas VDR expression was suppressed upon the treatment of 1,25-dihydroxyvitamin D3 or EGR1. VDR was identified as a target gene of miR-675. The H19 promoter and EGR1 increased the luciferase activity of cells transfected with wild-type VDR. Compared with DM patients free of DN, the levels of H19 and miR-675 were increased in the DN(+) group, whereas the levels of VDR and EGR1 were decreased. In summary, the above results indicate the presence of a negative feedback loop in the pathological mechanism of DN, where H19 downregulates the expression of VDR by upregulating the expression of miR-675, whereas reduced VDR expression subsequently reduced the expression of EGR1. Moreover, reduced EGR1 expression inhibits H19 expression, thus forming a negative feedback loop required to maintain the homeostasis of VDR and to reduce the incidence of DN.