Molecular Aspects Involved in the Mechanisms of Bothrops jararaca Venom-Induced Hyperalgesia: Participation of NK1 Receptor and Glial Cells

Accidents caused by Bothrops jararaca (Bj) snakes result in several local and systemic manifestations, with pain being a fundamental characteristic. The inflammatory process responsible for hyperalgesia induced by Bj venom (Bjv) has been studied; however, the specific roles played by the peripheral and central nervous systems in this phenomenon remain unclear. To clarify this, we induced hyperalgesia in rats using Bjv and collected tissues from dorsal root ganglia (DRGs) and spinal cord (SC) at 2 and 4 h post-induction. Samples were labeled for Iba-1 (macrophage and microglia), GFAP (satellite cells and astrocytes), EGR1 (neurons), and NK1 receptors. Additionally, we investigated the impact of minocycline, an inhibitor of microglia, and GR82334 antagonist on Bjv-induced hyperalgesia. Our findings reveal an increase in Iba1 in DRG at 2 h and EGR1 at 4 h. In the SC, markers for microglia, astrocytes, neurons, and NK1 receptors exhibited increased expression after 2 h, with EGR1 continuing to rise at 4 h. Minocycline and GR82334 inhibited venom-induced hyperalgesia, highlighting the crucial roles of microglia and NK1 receptors in this phenomenon. Our results suggest that the hyperalgesic effects of Bjv involve the participation of microglial and astrocytic cells, in addition to the activation of NK1 receptors.

ATF3/EGR1 regulates myocardial ischemia/reperfusion injury induced autophagy and inflammation in cardiomyocytes

Myocardial ischemia/reperfusion injury (MIRI) is an irreversible adverse event during the management of coronary heart disease that lacks effective controls. The underlying mechanism of MIRI still requires further investigation. Recent studies have suggested that overexpression of ATF3 protects against MIRI by regulating inflammatory responses, ferroptosis, and autophagy. The downstream target of ATF3, EGR1, also showed cardioprotective properties against MIRI by promoting autophagy. Therefore, further investigating the effect of ATF3/EGR1 pathway on MIRI-induced inflammation and autophagy is needed. Cardiomyocyte MIRI model was established by challenging H9C2 cells with hypoxia/reoxygenation (H/R). The ATF3 overexpression-H/R cell model by transfecting ATF3 plasmid into the H9C2 cell line. The transcription levels of ATF3 and EGR1 were determined using RT-qPCR, the levels of TNF-α and IL-6 were determined using ELISA kits, the protein expression of LC3 I, LC3 II, and P62 was determined via WB, and microstructure of H9C2 cell was observed by transmission electron microscopy (TEM). Overexpression of ATF3 significantly downregulated Egr1 levels, indicating that EGR1 might be the target of ATF3. By upregulating ATF3 levels, the extracellular levels of the inflammatory cytokines TNF-α and IL-6 significantly decreased, and the protein expression of the autophagy markers LC3 I, LC3 II, and P62 significantly increased. TEM results revealed that the cell line in the H/R-ATF3 group exhibited a higher abundance of autophagosome enclosures of mitochondria. The results indicated that ATF3/EGR1 may alleviate inflammation and improve autophagy in an H/R-induced MIRI model of cardiomyocytes.

GINS2 regulates temozolomide chemosensitivity via the EGR1/ECT2 axis in gliomas

Temozolomide (TMZ), a DNA alkylating agent, has become the primary treatment for glioma, the most common malignancy of the central nervous system. Although TMZ-containing regimens produce significant clinical response rates, some patients inevitably suffer from inferior treatment outcomes or disease relapse, likely because of poor chemosensitivity of glioma cells due to a robust DNA damage response (DDR). GINS2, a subunit of DNA helicase, contributes to maintaining genomic stability and is highly expressed in various cancers, promoting their development. Here, we report that GINS2 was upregulated in TMZ-treated glioma cells and co-localized with γH2AX, indicating its participation in TMZ-induced DDR. Furthermore, GINS2 regulated the malignant phenotype and TMZ sensitivity of glioma cells, mostly by promoting DNA damage repair by affecting the mRNA stability of early growth response factor 1 (EGR1), which in turn regulates the transcription of epithelial cell-transforming sequence 2 (ECT2). We constructed a GINS2-EGR1-ECT2 prognostic model, which accurately predicted patient survival. Further, we screened Palbociclib/BIX-02189 which dampens GINS2 expression and synergistically inhibits glioma cell proliferation with TMZ. These findings delineate a novel mechanism by which GINS2 regulates the TMZ sensitivity of glioma cells and propose a promising combination therapy to treat glioma.

EGR1 Regulates SHANK3 Transcription at Different Stages of Brain Development

The expression levels of SHANK3 are associated with autism spectrum disorder (ASD). The dynamic changes in SHANK3 expression during different stages of brain development may impact the progression of ASD. However, no studies or detailed analyses exploring the upstream mechanisms that regulate SHANK3 expression have been reported. In this study, we employed immunofluorescence to examine the expression of SHANK3 in brain organoids at various stages. Our results revealed elevated levels of SHANK3 expression in brain-like organoids at Day 60. Additionally, we utilized bioinformatics software to predict and analyze the SHANK3 gene's transcription start site. Through the dual luciferase reporter gene technique, we identified core transcription elements within the SHANK3 promoter. Site-directed mutations were used to identify specific transcription sites of SHANK3. To determine the physical binding of potential transcription factors to the SHANK3 promoter, we employed electrophoretic mobility shift assay (EMSA) and chromatin immunoprecipitation (ChIP). Our findings demonstrated that the transcription factor EGR1 regulates SHANK3 expression by binding to the transcription site of the SHANK3 promoter. Although this study did not investigate the pathological phenotypes of human brain organoids or animal model brains with EGR1 deficiency, which could potentially substantiate the findings observed for SHANK3 mutants, our findings provide valuable insights into the relationship between the transcription factor, EGR1, and SHANK3. This study contributes to the molecular understanding of ASD and offers potential foundations for precise targeted therapy.

EGR1 mediates MDR1 transcriptional activity regulating gemcitabine resistance in pancreatic cancer

BACKGROUND

Gemcitabine is a cornerstone drug for the treatment of all stages of pancreatic cancer and can prolong the survival of patients with pancreatic cancer, but resistance to gemcitabine in pancreatic cancer patients hinders its efficacy. The overexpression of Early growth response 1(EGR1) in pancreatic ductal adenocarcinoma as a mechanism of gemcitabine chemoresistance in pancreatic cancer has not been explored. The major mechanisms of gemcitabine chemoresistance are related to drug uptake, metabolism, and action. One of the common causes of tumor multidrug resistance (MDR) to chemotherapy in cancer cells is that transporter proteins increase intracellular drug efflux and decrease drug concentrations by inducing anti-apoptotic mechanisms. It has been reported that gemcitabine binds to MDR1 with high affinity. The purpose of this research was to investigate the potential mechanisms by which EGR1 associates with MDR1 to regulate gemcitabine resistance in pancreatic cancer cells.

METHODS

The following in vitro and in vivo techniques were used in this research to explore the potential mechanisms by which EGR1 binds to MDR1 to regulate gemcitabine resistance in pancreatic cancer cells. Cell culture; in vitro and in vivo study of EGR1 function by loss of function analysis. Binding of EGR1 to the MDR1 promoter was detected using the ChIP assay. qRT-PCR, Western blot assays to detect protein and mRNA expression; use of Annexin V apoptosis detection assay to test apoptosis; CCK8, Edu assay to test cell proliferation viability. The animal model of pancreatic cancer subcutaneous allograft was constructed and the tumours were stained with hematoxylin eosin and Ki-67 expression was detected using immunohistochemistry.

FINDINGS

We revealed that EGR1 expression was increased in different pancreatic cancer cell lines compared to normal pancreatic ductal epithelial cells. Moreover, gemcitabine treatment induced upregulation of EGR1 expression in a dose- and time-dependent manner. EGR1 is significantly enriched in the MDR1 promoter sequence.Upon knockdown of EGR1, cell proliferation was impaired in CFPAC-1 and PANC-1 cell lines, apoptosis was enhanced and MDR1 expression was decreased, thereby partially reversing gemcitabine chemoresistance. In animal experiments, knockdown of EGR1 enhanced the inhibitory effect of gemcitabine on tumor growth compared with the sh-NC group.

CONCLUSIONS

Our study suggests that EGR1 may be involved in the regulation of MDR1 to enhance gemcitabine resistance in pancreatic cancer cells. EGR1 could be a novel therapeutic target to overcome gemcitabine resistance in pancreatic cancer.

EGR1 transcriptionally regulates SVEP1 to promote proliferation and migration in human coronary artery smooth muscle cells

A low-frequency variant of sushi, von Willebrand factor type A, EGF, and pentraxin domain-containing protein 1 (SVEP1) is associated with the risk of coronary artery disease, as determined by a genome-wide association study. SVEP1 induces vascular smooth muscle cell proliferation and an inflammatory phenotype to promote atherosclerosis. In the present study, qRT‒PCR demonstrated that the mRNA expression of SVEP1 was significantly increased in atherosclerotic plaques compared to normal tissues. Bioinformatics revealed that EGR1 was a transcription factor for SVEP1. The results of the luciferase reporter assay, siRNA interference or overexpression assay, mutational analysis and ChIP confirmed that EGR1 positively regulated the transcriptional activity of SVEP1 by directly binding to its promoter. EGR1 promoted human coronary artery smooth muscle cell (HCASMC) proliferation and migration via SVEP1 in response to oxidized low-density lipoprotein (ox-LDL) treatment. Moreover, the expression level of EGR1 was increased in atherosclerotic plaques and showed a strong linear correlation with the expression of SVEP1. Our findings indicated that EGR1 binding to the promoter region drive SVEP1 transcription to promote HCASMC proliferation and migration.

PTZ-kindled rat model; evaluation of seizure, hippocampal EGR-1, and Rev-erbα gene regulation, behavioral analysis, and antioxidant capacity of Gum Arabic

BACKGROUND

Epilepsy is a neurological disease characterized by recurrent seizures, hyperexcitable neurons and various behavioral comorbidities. The electrical charge during seizures depletes the antioxidant defense mechanism in the epileptic brain and increases the oxidative burden. Natural antioxidant compounds are potential therapeutics in the treatment of two major pathologies of epilepsy with their anticonvulsant and anxiolytic effects and can modulate these targets. Gum Arabic is one of the natural plant polysaccharides that is non-toxic and biodegradable.

METHODS AND RESULTS

A total of 30 Wistar albino male rats (8-12 weeks, 350-500 g), were randomly divided into 5 groups with 6 animals in each group: 1-Control, 2-Sham (Phosphate buffer saline (PBS)), 3-PTZ, 4-Gum Arabic, 5-PTZ + Gum Arabic. PTZ was administered i.p at 35 mg/kg/day for 11 days. After 48 h, the injection was completed with 75 mg/kg PTZ. Locomotor activity, immobilization, rearing, grooming, eating, and drinking behaviors were recorded with the LABORAS behavior system for 30 min after kindling. Animals were treated with Gum Arabic (2 mg/kg/day, oral gavage) for 10 days. At the end of the period, animal behavior was recorded again. Then the hippocampus tissues were removed. Oxidative parameters (TAS and TOS), early growth response 1 (EGR1) and nuclear receptor subfamily 1 group D member 1 (Rev-erbα) gene expressions and behaviors were analyzed.

CONCLUSION

Gum Arabic increased TAS levels (P = 0.000), decreased TOS levels (P = 0.000), and thus exhibited antioxidant properties by reducing oxidative stress burden. EGR1, which was upregulated in the seizure group, was downregulated after treatment (P = 0.000), and Rev-erbα was downregulated in seizure and upregulated after treatment (P = 0.000). Gum arabic may be an antiepileptic and anxiolytic therapeutic in improving epileptic seizures by reducing oxidative stress burden through EGR1 and Rev-erbα.0.

EGR1 suppresses HCC growth and aerobic glycolysis by transcriptionally downregulating PFKL

BACKGROUND

Hepatocellular Carcinoma (HCC) is a matter of great global public health importance; however, its current therapeutic effectiveness is deemed inadequate, and the range of therapeutic targets is limited. The aim of this study was to identify early growth response 1 (EGR1) as a transcription factor target in HCC and to explore its role and assess the potential of gene therapy utilizing EGR1 for the management of HCC.

METHODS

In this study, both in vitro and in vivo assays were employed to examine the impact of EGR1 on the growth of HCC. The mouse HCC model and human organoid assay were utilized to assess the potential of EGR1 as a gene therapy for HCC. Additionally, the molecular mechanism underlying the regulation of gene expression and the suppression of HCC growth by EGR1 was investigated.

RESULTS

The results of our investigation revealed a notable decrease in the expression of EGR1 in HCC. The decrease in EGR1 expression promoted the multiplication of HCC cells and the growth of xenografted tumors. On the other hand, the excessive expression of EGR1 hindered the proliferation of HCC cells and repressed the development of xenografted tumors. Furthermore, the efficacy of EGR1 gene therapy was validated using in vivo mouse HCC models and in vitro human hepatoma organoid models, thereby providing additional substantiation for the anti-cancer role of EGR1 in HCC. The mechanistic analysis demonstrated that EGR1 interacted with the promoter region of phosphofructokinase-1, liver type (PFKL), leading to the repression of PFKL gene expression and consequent inhibition of PFKL-mediated aerobic glycolysis. Moreover, the sensitivity of HCC cells and xenografted tumors to sorafenib was found to be increased by EGR1.

CONCLUSION

Our findings suggest that EGR1 possesses therapeutic potential as a tumor suppressor gene in HCC, and that EGR1 gene therapy may offer benefits for HCC patients.

Blocking EGR1/TGF-β1 and CD44s/STAT3 Crosstalk Inhibits Peritoneal Metastasis of Gastric Cancer

Peritoneal metastasis (PM) continues to limit the clinical efficacy of gastric cancer (GC). Early growth response 1 (EGR1) plays an important role in tumor cell proliferation, angiogenesis and invasion. However, the role of EGR1 derived from the tumor microenvironment in reshaping the phenotypes of GC cells and its specific molecular mechanisms in increasing the potential for PM are still unclear. In this study, we reported that EGR1 was significantly up-regulated in mesothelial cells from GC peritoneal metastases, leading to enhanced epithelial-mesenchymal transformation (EMT) and stemness phenotypes of GC cells under co-culture conditions. These phenotypes were achieved through the transcription and secretion of TGF-β1 by EGR1 in mesothelial cells, which could regulate the expression and internalization of CD44s. After being internalized into the cytoplasm, CD44s interacted with STAT3 to promote STAT3 phosphorylation and activation, and induced EMT and stemness gene transcription, thus positively regulating the metastasis of GC cells. Moreover, TGF-β1 secretion in the PM microenvironment was significantly increased compared with the matched primary tumor. The blocking effect of SHR-1701 on TGF-β1 was verified by inhibiting peritoneal metastases in xenografts. Collectively, the interplay of EGR1/TGF-β1/CD44s/STAT3 signaling between mesothelial cells and GC cells induces EMT and stemness phenotypes, offering potential as a therapeutic target for PM of GC.

The guanine nucleotide exchange factor RapGEF2 is required for ERK-dependent immediate-early gene (Egr1) activation during fear memory formation

The MAP kinase ERK is important for neuronal plasticity underlying associative learning, yet specific molecular pathways for neuronal ERK activation are undetermined. RapGEF2 is a neuron-specific cAMP sensor that mediates ERK activation. We investigated whether it is required for cAMP-dependent ERK activation leading to other downstream neuronal signaling events occurring during associative learning, and if RapGEF2-dependent signaling impairments affect learned behavior. Camk2α-cre+/-::RapGEF2fl/fl mice with depletion of RapGEF2 in hippocampus and amygdala exhibit impairments in context- and cue-dependent fear conditioning linked to corresponding impairment in Egr1 induction in these two brain regions. Camk2α-cre+/-::RapGEF2fl/fl mice show decreased RapGEF2 expression in CA1 and dentate gyrus associated with abolition of pERK and Egr1, but not of c-Fos induction, following fear conditioning, impaired freezing to context after fear conditioning, and impaired cAMP-dependent long-term potentiation at perforant pathway and Schaffer collateral synapses in hippocampal slices ex vivo. RapGEF2 expression is largely eliminated in basolateral amygdala, also involved in fear memory, in Camk2α-cre+/-::RapGEF2fl/fl mice. Neither Egr1 nor c-fos induction in BLA after fear conditioning, nor cue-dependent fear learning, are affected by ablation of RapGEF2 in BLA. However, Egr1 induction (but not that of c-fos) in BLA is reduced after restraint stress-augmented fear conditioning, as is freezing to cue after restraint stress-augmented fear conditioning, in Camk2α-cre+/-::RapGEF2fl/fl mice. Cyclic AMP-dependent GEFs have been genetically associated as risk factors for schizophrenia, a disorder associated with cognitive deficits. Here we show a functional link between one of them, RapGEF2, and cognitive processes involved in associative learning in amygdala and hippocampus.

Ladostigil Reduces the Adenoside Triphosphate/Lipopolysaccharide-Induced Secretion of Pro-Inflammatory Cytokines from Microglia and Modulate-Immune Regulators, TNFAIP3, and EGR1

Treatment of aging rats for 6 months with ladostigil (1 mg/kg/day) prevented a decline in recognition and spatial memory and suppressed the overexpression of gene-encoding pro-inflammatory cytokines, TNFα, IL1β, and IL6 in the brain and microglial cultures. Primary cultures of mouse microglia stimulated by lipopolysaccharides (LPS, 0.75 µg/mL) and benzoyl ATPs (BzATP) were used to determine the concentration of ladostigil that reduces the secretion of these cytokine proteins. Ladostigil (1 × 10-11 M), a concentration compatible with the blood of aging rats in, prevented memory decline and reduced secretion of IL1β and IL6 by ≈50%. RNA sequencing analysis showed that BzATP/LPS upregulated 25 genes, including early-growth response protein 1, (Egr1) which increased in the brain of subjects with neurodegenerative diseases. Ladostigil significantly decreased Egr1 gene expression and levels of the protein in the nucleus and increased TNF alpha-induced protein 3 (TNFaIP3), which suppresses cytokine release, in the microglial cytoplasm. Restoration of the aberrant signaling of these proteins in ATP/LPS-activated microglia in vivo might explain the prevention by ladostigil of the morphological and inflammatory changes in the brain of aging rats.

EGR1/LINC00839/SOX5 axis modulates migration, invasion and Gemcitabine resistance of bladder cancer cells

BACKGROUND

Bladder cancer is one of the most common malignant tumors of the urinary system, and its incidence is increasing worldwide. However, the underlying mechanisms that trigger migration, invasion and chemotherapy resistance are unclear.

RESULTS

Bioinformatics analysis of bladder cancer cohort indicated that LINC00839 is deregulated in bladder cancer. LINC00839 was validated and highly expressed in bladder cancer patients and cell lines. In addition, LINC00839 induced the migration, invasion and Gemcitabine resistance of bladder cancer cells. We identified that the transcription factor EGR1 directly repressed LINC00839 and thereby suppressed the migration and invasion of bladder cancer cells. Furthermore, LINC00839 interacted with miR-142, which subsequently regulated the expression of SOX5, a well-studied oncogene and targeted by miR-142. In addition, EGR1 served as a suppressive transcription factor of SOX5. Therefore, EGR1 directly or indirectly regulates SOX5 via LINC00839/miR-142 axis. LINC00839 induced Gemcitabine resistance by promoting autophagy.

CONCLUSIONS

EGR1, LINC00839/miR-142 and SOX5 form a coherent feed-forward loop that modulates the migration, invasion and Gemcitabine resistance of bladder cancer.

Isogenic pairs of induced-pluripotent stem-derived endothelial cells identify DYRK1A/PPARG/EGR1 pathway is responsible for Down syndrome-associated pulmonary hypertension

Down syndrome (DS) is the most prevalent chromosomal disorder associated with a higher incidence of pulmonary arterial hypertension (PAH). The dysfunction of vascular endothelial cells (ECs) is known to cause pulmonary arterial remodeling in PAH, although the physiological characteristics of ECs harboring trisomy 21 (T21) are still unknown. In this study, we analyzed the human vascular ECs by utilizing the isogenic pairs of T21-induced pluripotent stem cells (iPSCs) and corrected disomy 21 (cDi21)-iPSCs. In T21-iPSC-derived ECs, apoptosis and mitochondrial reactive oxygen species (mROS) were significantly increased, and angiogenesis and oxygen consumption rate (OCR) were significantly impaired as compared with cDi21-iPSC-derived ECs. The RNA-sequencing identified that EGR1 on chromosome 5 was significantly upregulated in T21-ECs. Both EGR1 suppression by siRNA and pharmacological inhibitor could recover the apoptosis, mROS, angiogenesis, and OCR in T21-ECs. Alternately, the study also revealed that DYRK1A was responsible to increase EGR1 expression via PPARG suppression, and that chemical inhibition of DYRK1A could restore the apoptosis, mROS, angiogenesis, and OCR in T21-ECs. Finally, we demonstrated that EGR1 was significantly upregulated in the pulmonary arterial ECs from lung specimens of a patient with DS and PAH. In conclusion, DYRK1A/PPARG/EGR1 pathway could play a central role for the pulmonary EC functions and thus be associated with the pathogenesis of PAH in DS.

Transcriptome Profiling of Cardiac Glycoside Treatment Reveals EGR1 and Downstream Proteins of MAPK/ERK Signaling Pathway in Human Breast Cancer Cells

Cardiac glycosides (CGs) constitute a group of steroid-like compounds renowned for their effectiveness in treating cardiovascular ailments. In recent times, there has been growing recognition of their potential use as drug leads in cancer treatment. In our prior research, we identified three highly promising CG compounds, namely lanatoside C (LC), peruvoside (PS), and strophanthidin (STR), which exhibited significant antitumor effects in lung, liver, and breast cancer cell lines. In this study, we investigated the therapeutic response of these CGs, with a particular focus on the MCF-7 breast cancer cell line. We conducted transcriptomic profiling and further validated the gene and protein expression changes induced by treatment through qRT-PCR, immunoblotting, and immunocytochemical analysis. Additionally, we demonstrated the interactions between the ligands and target proteins using the molecular docking approach. The transcriptome analysis revealed a cluster of genes with potential therapeutic targets involved in cytotoxicity, immunomodulation, and tumor-suppressor pathways. Subsequently, we focused on cross-validating the ten most significantly expressed genes, EGR1, MAPK1, p53, CCNK, CASP9, BCL2L1, CDK7, CDK2, CDK2AP1, and CDKN1A, through qRT-PCR, and their by confirming the consistent expression pattern with RNA-Seq data. Notably, among the most variable genes, we identified EGR1, the downstream effector of the MAPK signaling pathway, which performs the regulatory function in cell proliferation, tumor invasion, and immune regulation. Furthermore, we substantiated the influence of CG compounds on translational processes, resulting in an alteration in protein expression upon treatment. An additional analysis of ligand-protein interactions provided further evidence of the robust binding affinity between LC, PS, and STR and their respective protein targets. These findings underscore the intense anticancer activity of the investigated CGs, shedding light on potential target genes and elucidating the probable mechanism of action of CGs in breast cancer.

Evaluating Gene Expression and Methylation Profiles of TCF4, MBP, and EGR1 in Peripheral Blood of Drug-Free Patients with Schizophrenia: Correlations with Psychopathology, Intelligence, and Cognitive Impairment

Discovery and validation of new, reliable diagnostic and predictive biomarkers for schizophrenia (SCZ) are an ongoing effort. Here, we assessed the mRNA expression and DNA methylation of the TCF4, MBP, and EGR1 genes in the blood of patients with SCZ and evaluated their relationships to psychopathology and cognitive impairments. Quantitative real-time PCR and quantitative methylation-specific PCR methods were used to assess the expression level and promoter DNA methylation status of these genes in 70 drug-free SCZ patients and 72 healthy controls. The correlation of molecular changes with psychopathology and cognitive performance of participants was evaluated. We observed downregulation of TCF4 and upregulation of MBP mRNA levels in SCZ cases, relative to controls in our study. DNA methylation status at the promoter region of TCF4 demonstrated an altered pattern in SCZ as well. Additionally, TCF4 mRNA levels were inversely correlated with PANSS and Stroop total errors and positively correlated with WAIS total score and working memory, consistent with previous studies by our group. In contrast, MBP mRNA level was significantly positively correlated with PANSS and Stroop total errors and inversely correlated with WAIS total score and working memory. These epigenetic and expression signatures can help to assemble a peripheral biomarker-based diagnostic panel for SCZ.

EGR1 Regulation of Vasculogenic Mimicry in the MDA-MB-231 Triple-Negative Breast Cancer Cell Line through the Upregulation of KLF4 Expression

Vasculogenic mimicry (VM) is an intriguing phenomenon observed in tumor masses, in which cancer cells organize themselves into capillary-like channels that closely resemble the structure and function of blood vessels. Although VM is believed to contribute to alternative tumor vascularization, the detailed regulatory mechanisms controlling these cellular processes remain poorly understood. Our study aimed to investigate the role of Early Growth Response 1 (EGR1) in regulating VM in aggressive cancer cells, specifically MDA-MB-231 triple-negative breast cancer cells. Our study revealed that EGR1 promotes the formation of capillary-like tubes by MDA-MB-231 cells in a 3-dimensional Matrigel matrix. EGR1 was observed to upregulate Kruppel-like factor 4 (KLF4) expression, which regulates the formation of the capillary-like tube structure. Additionally, our findings highlight the involvement of the ERK1/2 and p38 mitogen-activated protein kinase pathways in mediating the expression of EGR1 and KLF4, underscoring their crucial role in VM in MDA-MB-231 cells. Understanding these regulatory mechanisms will provide valuable insights into potential therapeutic targets for preventing VM during the treatment of triple-negative breast cancer.

Fibronectin Contributes to a BRAF Inhibitor-driven Invasive Phenotype in Thyroid Cancer through EGR1, Which Can Be Blocked by Inhibition of ERK1/2

Mutations in BRAF are common in advanced papillary and anaplastic thyroid cancer (PTC and ATC). However, patients with BRAF-mutant PTC currently lack therapies targeting this pathway. Despite the approved combination of BRAF and MEK1/2 inhibition for patients with BRAF-mutant ATC, these patients often progress. Thus, we screened a panel of BRAF-mutant thyroid cancer cell lines to identify new therapeutic strategies. We showed that thyroid cancer cells resistant to BRAF inhibition (BRAFi) exhibit an increase in invasion and a proinvasive secretome in response to BRAFi. Using reverse-phase protein array (RPPA), we identified a nearly 2-fold increase in expression of the extracellular matrix protein, fibronectin, in response to BRAFi treatment, and a corresponding 1.8- to 3.0-fold increase in fibronectin secretion. Accordingly, the addition of exogenous fibronectin phenocopied the BRAFi-induced increase in invasion while depletion of fibronectin in resistant cells resulted in loss of increased invasion. We further showed that BRAFi-induced invasion can be blocked by inhibition of ERK1/2. In a BRAFi-resistant patient-derived xenograft model, we found that dual inhibition of BRAF and ERK1/2 slowed tumor growth and decreased circulating fibronectin. Using RNA sequencing, we identified EGR1 as a top downregulated gene in response to combined BRAF/ERK1/2 inhibition, and we further showed that EGR1 is necessary for a BRAFi-induced increase in invasion and for induction of fibronectin in response to BRAFi.

IMPLICATIONS

Together, these data show that increased invasion represents a new mechanism of resistance to BRAF inhibition in thyroid cancer that can be targeted with an ERK1/2 inhibitor.

Tenogenic differentiation of human tendon-derived stem cells induced by long non-coding RNA LINCMD1 via miR-342-3p/EGR1 axis

BACKGROUND

Tendon-derived stem cells (TDSCs) are proposed as a potential cell-seed for the treatment of tendon injury due to their tenogenic differentiation potential. In this work, we defined the action of long non-coding RNA (lncRNA) muscle differentiation 1 (LINCMD1) in tenogenic differentiation of human TDSCs (hTDSCs).

METHODS

Quantitative real-time PCR (qRT-PCR) was used to assess the levels of LINCMD1, microRNA (miR)-342-3p, and early growth response-1 (EGR1) mRNA. Cell proliferation was detected by the XTT colorimetric assay. Protein expression was quantified by western blot. hTDSCs were grown in an osteogenic medium to induce osteogenic differentiation, and the extent of osteogenic differentiation was assessed by Alizarin Red Staining (ARS). The activity of alkaline phosphatase (ALP) was measured by the ALP Activity Assay Kit. Dual-luciferase reporter and RNA immunoprecipitation (RIP) assays were used to evaluate the direct relationship between miR-342-3p and LINCMD1 or EGR1.

RESULTS

Our results showed that enforced expression of LINCMD1 or suppression of miR-342-3p accelerated the proliferation and tenogenic differentiation and reduced osteogenic differentiation of hTDSCs. LINCMD1 regulated miR-342-3p expression by binding to miR-342-3p. EGR1 was identified as a direct and functional target of miR-342-3p, and knockdown of EGR1 reversed the effects of miR-342-3p suppression on cell proliferation and tenogenic and osteogenic differentiation. Furthermore, the miR-342-3p/EGR1 axis mediated the regulation of LINCMD1 on hTDSC proliferation and tenogenic and osteogenic differentiation.

CONCLUSION

Our study suggests the induction of LINCMD1 in tenogenic differentiation of hTDSCs through miR-342-3p/EGR1 axis.

Iguratimod attenuated fibrosis in systemic sclerosis via targeting early growth response 1 expression

BACKGROUND

The early growth response 1 (EGR1) is a central transcription factor involved in systemic sclerosis (SSc) pathogenesis. Iguratimod is a synthesized anti-rheumatic disease-modifying drug, which shows drastic inhibition to EGR1 expression in B cells. This study is aiming to investigate the anti-fibrotic effect of iguratimod in SSc.

METHODS

EGR1 was detected by immunofluorescence staining real-time PCR or western blot. Iguratimod was applied in EGR1 overexpressed or knockdown human dermal fibroblast, bleomycin pre-treated mice, tight skin 1 mice, and SSc skin xenografts. RNA sequencing was performed in cultured fibroblast and xenografts to identify the iguratimod regulated genes.

RESULTS

EGR1 overexpressed predominantly in non-immune cells of SSc patients. Iguratimod reduced EGR1 expression in fibroblasts and neutralized changes of EGR1 response genes regulated by TGFβ. The extracellular matrix (ECM) production and activation of fibroblasts were attenuated by iguratimod while EGR1 overexpression reversed this effect of iguratimod. Iguratimod ameliorated the skin fibrosis induced by bleomycin and hypodermal fibrosis in TSK-1 mice. Decreasing in the collagen content as well as the density of EGR1 or TGFβ positive fibroblasts of skin xenografts from naïve SSc patients was observed after local treatment of iguratimod.

CONCLUSION

Targeting EGR1 expression is a probable underlying mechanism for the anti-fibrotic effect of iguratimod.

Early growth response 1 promoted the invasion of glioblastoma multiforme by elevating HMGB1

BACKGROUND

Glioblastoma multiforme (GBM) is the most common and deadly glioma subtype. Early growth response 1 (EGR1) participates in the progression of several cancer types, but the expression and function of EGR1 in GBM was rarely investigated.

METHODS

The expressions of EGR1 in GBM were detected with qRT-PCR and immunohistochemistry in 12 pairs of fresh GBM tissues and 116 paraffin-embedded specimens. The patients were divided into high and low EGR1 groups according to the IHC score of EGR1, and the prognostic significances of different groups were evaluated with univariate and multivariate analyses. With in-vitro experiments, we assessed the role of EGR1 in the proliferation and invasion of GBM cells.

RESULTS

In our study, EGR1 was up-regulated in GBM tissues compared with tumor-adjacent normal tissues. High expression of EGR1 or HMGB1 were unfavorable prognostic biomarkers of GBM. Coexpression of EGR1 and HMGB1 could predict the prognosis of GBM more sensitively. EGR1 facilitated the proliferation and invasion of GBM cells. Moreover, EGR1 promoted the invasion, instead of proliferation, of GBM cells by elevating the expression of HMGB1.

CONCLUSIONS

ERG1 was a prognostic biomarker of GBM, and ERG1 and HMGB1 synergistically could predict the GBM prognosis more precisely. ERG1 could promote GBM cell invasion by inducing HMGB1 expression.

CNN2 silencing inhibits colorectal cancer development through promoting ubiquitination of EGR1

Colorectal cancer (CRC) is one of the most commonly diagnosed malignant tumors of the digestive tract. H2-calponin (CNN2), an actin cytoskeleton-binding protein, is an isoform of the calponin protein family whose role in CRC is still unknown. Research based on clinical samples showed the up-regulation of CNN2 in CRC and its association with tumor development, metastasis, and poor prognosis of patients. Both in vitro loss-of-function and gain-of-function experiments showed that CNN2 participates in CRC development through influencing malignant cell phenotypes. In vivo, xenografts formed by CNN2 knockdown cells also showed a slower growth rate and smaller final tumors. Furthermore, EGR1 was identified as a downstream of CNN2, forming a complex with CNN2 and YAP1 and playing an essential role in the CNN2-induced regulation of CRC development. Mechanistically, CNN2 knockdown down-regulated EGR1 expression through enhancing its ubiquitination, thus decreasing its protein stability in a YAP1-dependent manner. In summary, CNN2 plays an EGR1-dependent promotion role in the development and progression of CRC, which may be a promising therapeutic target for CRC treatment.

EGR1 induces EMT in pancreatic cancer via a P300/SNAI2 pathway

BACKGROUND

The prognosis of pancreatic cancer patients remains relatively poor. Although some patients would receive surgical resection, distant metastasis frequently occurs within one year. Epithelial-mesenchymal transition (EMT), as a pathological mechanism in cancer progression, contributed to the local and distant metastasis of pancreatic cancer.

METHODS

Tissue microarray analysis and immunohistochemistry assays were used to compare the expression of EGR1 in pancreatic cancer and normal pancreatic tissues. Transwell chambers were used to evaluated the migration and invasion ability of cancer cells. Immunofluorescence was utilized to assess the expression of E-cadherin. ChIP-qPCR assay was applied to verify the combination of EGR1 and SNAI2 promoter sequences. Dual-luciferase reporter assay was used to detect the gene promoter activation. Co-IP assay was conducted to verify the interaction of EGR1 and p300/CBP.

RESULTS

EGR1 was highly expressed in pancreatic cancer rather than normal pancreatic tissues and correlated with poor prognosis and cancer metastasis. EGR1 was proved to enhance the migration and invasion ability of pancreatic cells. Besides, EGR1 was positively correlated with EMT process in pancreatic cancer, via a SNAI2-dependent pathway. P300/CBP was found to play an auxiliary role in the transcriptional activation of the SNAI2 gene by EGR1. Finally, in vivo experiments also proved that EGR1 promoted liver metastasis of pancreatic cancer.

CONCLUSION

Our findings implied the EMT-promoting effect of EGR1 in pancreatic cancer and revealed the intrinsic mechanism. Blocking the expression of EGR1 may be a new anticancer strategy for pancreatic cancer.

EGR1 drives cell proliferation by directly stimulating TFEB transcription in response to starvation

The stress-responsive transcription factor EB (TFEB) is a master controller of lysosomal biogenesis and autophagy and plays a major role in several cancer-associated diseases. TFEB is regulated at the posttranslational level by the nutrient-sensitive kinase complex mTORC1. However, little is known about the regulation of TFEB transcription. Here, through integrative genomic approaches, we identify the immediate-early gene EGR1 as a positive transcriptional regulator of TFEB expression in human cells and demonstrate that, in the absence of EGR1, TFEB-mediated transcriptional response to starvation is impaired. Remarkably, both genetic and pharmacological inhibition of EGR1, using the MEK1/2 inhibitor Trametinib, significantly reduced the proliferation of 2D and 3D cultures of cells displaying constitutive activation of TFEB, including those from a patient with Birt-Hogg-Dubé (BHD) syndrome, a TFEB-driven inherited cancer condition. Overall, we uncover an additional layer of TFEB regulation consisting in modulating its transcription via EGR1 and propose that interfering with the EGR1-TFEB axis may represent a therapeutic strategy to counteract constitutive TFEB activation in cancer-associated conditions.

Hepatocyte Ninjurin2 promotes hepatic stellate cell activation and liver fibrosis through the IGF1R/EGR1/PDGF-BB signaling pathway

BACKGROUND

Liver fibrogenesis is orchestrated by the paracrine signaling interaction between several resident cell types regulating the activation of hepatic stellate cells (HSCs). However, the molecular mechanisms underlying paracrine regulation are largely unknown. The aim of this study is to elucidate the role of Ninjurin2 in the crosstalk between hepatocytes and HSCs and better understand the implications of Ninjurin2 in liver fibrosis.

METHODS

Ninj2 knockout mice (Ninj2^-/-) and hepatocyte-specific Ninj2 overexpression mice (Ninj2^Hep-tg) were constructed and followed by the induction of liver fibrosis using methionine- and choline-deficient (MCD) diet. The relationship between Ninjurin2 and liver fibrosis phenotype was evaluated in vivo by measurement of fibrotic markers and related genes. We used an in vitro transwell cell co-culture model to examine the impact of Ninjurin2 in hepatocytes on the crosstalk to HSCs. The interaction of Ninjurin2 and IGF1R and the regulation of PI3K-AKT-EGR1 were analyzed in vivo and in vitro. Finally, an inhibitory Ninjurin2 peptide was injected intravenously via the tail vein to investigate whether inhibiting of Ninjurin2 cascade can attenuate MCD diet-induced liver fibrosis in mice.

RESULTS

We found that hepatic Ninjurin2 expression was significantly increased in fibrotic human liver and MCD diet-induced liver injury mouse models. In the mouse model, hepatocyte-specific overexpression of Ninj2 exacerbates MCD-induced liver fibrosis, while global Ninj2 knockout reverses the phenotype. To mimic hepatocyte-HSC crosstalk during liver fibrosis, we used co-culture systems containing hepatocytes and HSCs and determined that Ninjurin2 overexpression in hepatocytes directly activates HSCs in vitro. Mechanistically, Ninjurin2 directly interacts with insulin-like growth factor 1 receptor (IGF1R) and increases the hepatocyte secretion of the fibrogenic cytokine, platelet-derived growth factor-BB (PDGF-BB) through IGF1R-PI3K-AKT-EGR1 cascade. Inhibition of PDGFRB signaling in HSCs can abolish the profibrogenic effect of Ninjurin2. In addition, we demonstrated that a specific inhibitory Ninjurin2 peptide containing an N-terminal adhesion motif mitigates liver fibrosis and improves hepatic function in the mouse models by negatively regulating the sensitivity of IGF1R to IGF1 in hepatocytes.

CONCLUSION

Hepatic Ninjurin2 plays a key role in liver fibrosis through paracrine regulation of PDGF-BB/PDGFRB signaling in HSCs, and the results suggesting Ninjurin2 may be a potential therapeutic target.

The JNK-EGR1 signaling axis promotes TNF-α-induced endothelial differentiation of human mesenchymal stem cells via VEGFR2 expression

Mesenchymal stem cells (MSCs) can differentiate into endothelial cells; however, the mechanisms underlying this process in the tumor microenvironment (TME) remain elusive. This study shows that tumor necrosis factor alpha (TNF-α), a key cytokine present in the TME, promotes the endothelial differentiation of MSCs by inducing vascular endothelial growth factor receptor 2 (VEGFR2) gene expression. EGR1 is a member of the zinc-finger transcription factor family induced by TNF-α. Our findings indicate that EGR1 directly binds to the VEGFR2 promoter and transactivates VEGFR2 expression. We also demonstrate that EGR1 forms a complex with c-JUN activated by c-JUN N-terminal kinase (JNK) to promote VEGFR2 transcription and endothelial differentiation in MSCs in response to TNF-α stimulation. The shRNA-mediated silencing of EGR1 or c-JUN abrogates TNF-α-induced VEGFR2 transcription and the endothelial differentiation of MSCs. To further evaluated the role of EGR1 in the endothelial differentiation of BM-MSCs, we used a syngenic tumor implantation model. 4T1 mouse mammary tumor cells were injected subcutaneously into BALB/c mice with primary mBM-MSCs isolated from wild-type (Egr1+/+) or Egr1-null (Egr1-/-) mice. CD31-positive cells were predominantly observed at the border of the tumor in the 4T1 plus wild-type MSC group, while staining less in the 4T1 alone or 4T1 plus Egr1-null MSC group. Collectively, these findings demonstrate that the JNK-EGR1 signaling axis plays a crucial role in the TNF-α-induced endothelial differentiation of MSCs in the TME, which could be a potential therapeutic target for solid tumors vasculatures.

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.

Integrated analysis of mRNA-seq and miRNA-seq reveals the potential roles of Egr1, Rxra and Max in kidney stone disease

Nephrolithiasis is one of the most common and frequent urologic diseases worldwide. The molecular mechanism of kidney stone formation is complex and remains to be illustrated. Transcript factors (TFs) that influenced the expression pattern of multiple genes, as well as microRNAs, important posttranscriptional modulators, play vital roles in this disease progression. Datasets of nephrolithiasis mice and kidney stone patients were acquired from Gene Expression Omnibus repository. TFs were predicted from differentially expressed genes by RcisTarget. The target genes of differential-expressed microRNAs were predicted by miRWalk. MicroRNA-mRNA network and PPI network were constructed. Functional enrichment analysis was performed via Metascape and Cytoscape identified hub genes. The assay of quantitative real-time PCR (q-PCR) and immunochemistry and the datasets of oxalate diet-induced nephrolithiasis mice kidneys and kidney stone patients' samples were utilized to validate the bioinformatic results. We identified three potential key TFs (Egr1, Rxra, Max), which can be modulated by miR-181a-5p, miR-7b-3p and miR-22-3p, respectively. The TFs and their regulated hub genes influenced the progression of nephrolithiasis via altering the expression of genes enriched in the functions of fibrosis, cell proliferation and molecular transportation and metabolism. The expression changes of transcription factors were consistent in q-PCR and immunochemistry results. For regulated hub genes, they showed consistent expression changes in oxalate diet-induced nephrolithiasis mice model and human kidneys with stones. The identified and verified three TFs, which may be modulated by microRNAs in nephrolithiasis disease progression, mainly influence biological processes responding to fibrosis, proliferation and molecular transportation and metabolism. The transcript influence showed consistency in multiple nephrolithiasis mice models and kidney stone patients.

EGR1/NOX4 pathway regulates oxidative stress and further facilitates fibrosis progression in keloids responses to TGF-β1

BACKGROUND

As classic benign fibroproliferative tumors, keloids remain a major therapeutic challenge due to their complex pathological mechanisms.

OBJECTIVE

To determine the functional role of transforming growth factor β1 (TGF-β1)/early growth response factor-1 (EGR1)/NADPH oxidases 4 (NOX4) axis in the pathogenesis of keloid fibrosis.

METHODS

Differentially expressed genes in keloid tissues and normal skins were analyzed by RNA sequencing. Then, the human skin fibroblast cell line was treated with TGF-β1 at a dose of 10 ng/mL in order to stimulate the TGF-β1/SMAD pathway and the pathway was blocked using the SB431542. Furthermore, EGR1/NOX4 was over-expressed and inhibited by transfecting overexpression plasmids and small interfering RNAs, respectively. The levels of intracellular reactive oxygen species were measured using the DCFH-DA assay, and the expression levels of fibrosis-related genes were assessed by Western blot analysis. Alternately, dual-luciferase reporter analysis verified the targeting relationship between EGR1 and NOX4.

RESULTS

The TGF-β1/SMAD signaling pathway was significantly activated in keloid tissues to promote dermal fibrosis. The level of ROS was increased in keloid fibroblasts. Moreover, TGF-β1 could facilitate the expression of EGR1 through regulating the SMAD pathway in keloids and promoting the fibrotic phenotype of keloid fibroblasts. EGR1 could regulate the production of ROS by targeting NOX4. Furthermore, NOX4-derived ROS could promote fibrotic-like phenotype of keloid fibroblasts and play an important role in keloid fibrosis.

CONCLUSION

Our findings provide new insights into the mechanisms of the TGF-β1/EGR1/NOX4 pathway in keloid fibrosis, and the TGF-β1/EGR1/NOX4 axis may serve as a potential therapeutic target for keloids.

FOCAD/miR-491-5p, downregulated by EGR1, function as tumor suppressor by inhibiting the proliferation and migration of gastric cancer cells

Gastric cancer is a common malignant tumor in China; however, its carcinogenesis remains unknown. Focadhesin (FOCAD) is a tumor suppressor gene in gliomas, its expression, role, and mechanism in gastric cancer have not been defined. The aim of the present study was to explore the expression pattern of FOCAD in human normal tissues and cancer tissues and elucidate the role and regulatory mechanism of Early Growth Response 1 (EGR1) in FOCAD and its intron, miR-491-5p, in gastric cancer. Immuno histochemical staining revealed that FOCAD is widely and highly expressed in normal gastric mucosa, but is absent in gastric cancer tissue. Based on an association analysis FOCAD expression was found to be negatively associated with lymph node metastasis (P = 0.004); higher FOCAD levels were associated with longer survival in patients with gastric cancer (P = 0.001). MTT, colony, Transwell chamber, and flow cytometry assays revealed that siFOCAD promoted cell proliferation, growth, and migration, and inhibited apoptosis. Furthermore, bioinformatic analysis, Fluorescence reporter gene and chromatin immunoprecipitation analyses confirmed that EGR1 binds to the promoter and negatively regulates FOCAD and miR-491-5p at the transcriptional level. The overexpression of EGR1 was also found to promote cell proliferation, growth, and migration, and inhibit apoptosis. Overall, FOCAD is specifically overexpressed in the gastric mucosa and is significantly downregulated in gastric cancer. To our knowledge, this is the first study to demonstrate that FOCAD is a tumor suppressor, higher FOCAD levels might be a better prognostic marker of gastric cancer, and FOCAD/miR-491-5p may be negatively regulated by EGR1.

EGR1 Haploinsufficiency Confers a Fitness Advantage to Hematopoietic Stem Cells Following Chemotherapy

Therapy-related myeloid neoplasms (t-MNs) share many clinical and molecular characteristics with AML de novo in the elderly. One common factor is that they arise in the setting of chronic inflammation, likely because of advanced age or chemotherapy-induced senescence. Here, we examined the effect of haploinsufficient loss of the del(5q) tumor suppressor gene, EGR1, commonly deleted in high-risk MNs. In mice, under the exogenous stress of either serial transplant or successive doses of the alkylating agent N-ethyl-nitrosourea (ENU), Egr1-haploinsufficient hematopoietic stem cells (HSCs) exhibit a clonal advantage. Complete loss of EGR1 function is incompatible with transformation; mutations of EGR1 are rare and are not observed in the remaining allele in del(5q) patients, and complete knockout of Egr1 in mice leads to HSC exhaustion. Using chromatin immunoprecipitation sequencing (ChIP-seq), we identified EGR1 binding sites in human CD34+ cord blood-derived stem and progenitor cells (HSPCs) and found that EGR1 binds genes critical for stem cell differentiation, inflammatory signaling, and the DNA damage response. Notably, in the chromosome 5 sequences frequently deleted in patients, there is a significant enrichment of innate and inflammatory genes, which may confer a fitness advantage in an inflammatory environment. Short hairpin RNA (shRNA)-mediated silencing of EGR1 biases HSPCs toward a self-renewal transcriptional signature. In the absence of EGR1, HSPCs are characterized by upregulated MYC-driven proliferative signals, downregulated CDKN1A (p21), disrupted DNA damage response, and downregulated inflammation-adaptations anticipated to confer a relative fitness advantage for stem cells especially in an environment of chronic inflammation.

ERK-dependent induction of the immediate-early gene Egr1 and the late gene Gpr50 contribute to two distinct phases of PACAP Gs-GPCR signaling for neuritogenesis

Gs-coupled GPCR-stimulated neuritogenesis in PC12 and NS-1 - cells depends on activation of the MAP kinase ERK. Here, we examine changes in ERK activation (phosphorylation), and the time course of ERK-dependent gene induction, to seek transcriptional determinants for this process. Quenching of ERK activation by inhibition of MEK with U0126 at any time point for at least 24 h following addition of PACAP resulted in arrest of neurite formation. Changes in the transcriptome profile throughout this time period revealed at least two phases of gene induction: an early phase dominated by induction of immediate-early genes, and a later phase of gene induction after 4-6 h of exposure to PACAP with persistent elevation of phospho-ERK levels. Genes induced by PACAP in both phases consisted in those whose induction was dependent on ERK (i.e., blocked by U0126), and some whose induction was blocked by the protein kinase A inhibitor H89. ERK-dependent "late gene" transcripts included Gpr50, implicated earlier in facilitation of NGF-induced neurite formation in NS-1 cells. Gpr50 induction by PACAP, but not NGF, was dependent on the guanine nucleotide exchange factor RapGEF2, which has been shown to be required for PACAP-induced neuritogenesis in NS-1 cells. Expression of a Gpr50-directed shRNA lowered basal levels of Gpr50 mRNA and attenuated Gpr50 mRNA and GPR50 protein induction by PACAP, with a corresponding attenuation of PACAP-induced neuritogenesis. Gs-GPCR-stimulated neuritogenesis first requires immediate-early gene induction, including that of Egr1 (Zif268/NGF1A/Krox24) as previously reported. This early phase of gene induction, however, is insufficient to maintain the neuritogenic process without ERK-dependent induction of additional late genes, including Gpr50, upon continuous exposure to neurotrophic neuropeptide. Early (Egr1) and late (Gpr50) gene induction by NGF, like that for PACAP, was inhibited by U0126, but was independent of RapGEF2, confirming distinct modes of ERK activation by Gs-coupled GPCRs and neurotrophic tyrosine receptor kinases, converging on a final common ERK-dependent signaling pathway for neuritogenesis.

<i>ASXL1</i> mutations accelerate bone marrow fibrosis via EGR1-TNFA axis mediated neoplastic fibrocyte generation in myeloproliferative neoplasms

Apart from the central role of activated JAK/STAT signaling pathway, ASXL1 mutations are the most recurrent additional mutations in myeloproliferative neoplasms (MPNs) and occurred much more common in myelofibrosis (MF) than essential thrombocythemia (ET) and polycythemia vera (PV) patients. However, the mechanism of the association with ASXL1 mutations and bone marrow (BM) fibrosis remains unknown. Here, integrating our own data of MPN patients and hematopoietic-specific Asxl1 deletion/Jak2V617F mouse model, we show that ASXL1 mutations are associated with advanced MPN phenotypes and onset of myelofibrosis. ASXL1 mutations induce skewed monocyte/macrophage and neoplastic monocyte-derived fibrocyte differentiation, consequently enhance inflammation and BM fibrosis. Consistently, the loss of ASXL1 and JAK2V617F mutation in hematopoietic stem and progenitor cells (HSPCs) leads to enhancer activation of polycomb group (PcG) target genes, such as EGR1. The upregulation of EGR1, in turn accounts for increased HSPCs commitment to monocyte/macrophage lineage. Moreover, EGR1 induces the activation of TNFA and thereby further drives the differentiation of monocytes to fibrocytes. Accordingly, combined TNFR antagonist with ruxolitinib significantly reduces fibrocytes production in vitro. Altogether, these findings demonstrate that ASXL1 mutations accelerate fibrocyte production and inflammation in MPNs via EGR1-TNFA axis, providing cellular and molecular basis for BM fibrosis and proof-of-concept for anti-fibrosis treatment.

The Effect of EGR1 on the Proliferation of Dermal Papilla Cells

Early growth response factor 1 (EGR1) is a zinc-finger transcription factor that plays a vital role in the development of hair follicles. According to our previous studies, EGR1 is a transcriptional promoter of the bone morphogenetic protein 7 (BMP7), a candidate gene involved in the proliferation of dermal papilla cells. Since hair follicles are the basis of lambskin pattern formation and dermal papilla cells (DPCs) act on hair follicle growth, in order to elucidate the role of EGR1 and hair follicles, this study aimed to investigate the biological role of EGR1 in DPCs. In our study, the EGR1 coding sequence (CDS) region was firstly cloned by polymerase chain reaction, and bioinformatics analysis was performed. Then, the function of EGR1 was detected by 5-ethynyl-2’-deoxyuridine (EDU) and Cell Counting Kit-8 (CCK8), and Western blot (WB) was conducted to analyze the cellular effect of EGR1 on DPCs. The proliferative effect of EGR1 on DPCs was also further confirmed by detecting its expression by qPCR and WB on marker genes of proliferation, including PCNA and CDK2. The sequence of the EGR1 CDS region of a lamb was successfully cloned, and its nucleic acid sequence was analyzed and found to be highly homologous to Rattus norvegicus, Mus musculus, Bos taurus and Homo sapiens. Predictive analysis of the protein encoded by EGR1 revealed that it is an extra-membrane protein, and not a secretory protein, with subcellular localization in the nucleus and cytoplasm. The proliferative effect of DPCs was significantly stronger (p < 0.01) in EGR1 up-regulated DPCs compared to the controls, while the opposite result was observed in EGR1 down-regulated DPCs. Markers of proliferation including PCNA and CDK2 also appeared to be differentially upregulated in EGR1 gene overexpression compared to the controls, with the opposite result in EGR1 gene downregulation. In summary, our study revealed that EGR1 promotes the proliferation of DPCs, and we speculate that EGR1 may be closely associated with hair follicle growth and development.

Hippocampal Egr1-Dependent Neuronal Ensembles Negatively Regulate Motor Learning

Motor skills learning is classically associated with brain regions including cerebral and cerebellar cortices and basal ganglia nuclei. Less is known about the role of the hippocampus in the acquisition and storage of motor skills. Here, we show that mice receiving a long-term training in the accelerating rotarod display marked hippocampal transcriptional changes and reduced pyramidal neurons activity in the CA1 region when compared with naive mice. Then, we use mice in which neural ensembles are permanently labeled in an Egr1 activity-dependent fashion. Using these mice, we identify a subpopulation of Egr1-expressing pyramidal neurons in CA1 activated in short-term (STT) and long-term (LTT) trained mice in the rotarod task. When Egr1 is downregulated in the CA1 or these neuronal ensembles are depleted, motor learning is improved whereas their chemogenetic stimulation impairs motor learning performance. Thus, Egr1 organizes specific CA1 neuronal ensembles during the accelerating rotarod task that limit motor learning. These evidences highlight the role of the hippocampus in the control of this type of learning and we provide a possible underlying mechanism.SIGNIFICANCE STATEMENT It is a major topic in neurosciences the deciphering of the specific circuits underlying memory systems during the encoding of new information. However, the potential role of the hippocampus in the control of motor learning and the underlying mechanisms has been poorly addressed. In the present work we show how the hippocampus responds to motor learning and how the Egr1 molecule is one of the major responsible for such phenomenon controlling the rate of motor coordination performances.

METTL7B contributes to the malignant progression of glioblastoma by inhibiting EGR1 expression

Glioblastoma (GBM), a predominant central nervous system (CNS) malignancy, is correlated with high mortality and severe morbidity. Mammalian methyltransferase-like 7B (METTL7B) as a methyltransferase has been identified to participate in cancer progression. However, its function in GBM is elusive. Accordingly, we aimed to explore the effect of METTL7B on GBM. The expression of METTL7B and EGR2 in GBM patients and GBM cells were detected by qPCR, western blots and immunohistochemical staining. Cell viability was assessed by CCK-8 assays. Cell proliferation was determined by EdU, colony formation, and tumor sphere formation assays. METTL7B shRNA was injected into the Balb/c nude mice. The size and weight of isolated tumor was measured. And the expression levels of Ki67, METTL7B and EGR1 were examined by immunohistochemical staining. METTL7B was significantly elevated, while EGR1 was downregulated in clinical GBM tissues. METTL7B upregulation was associated with the low overall survival of GBM patients. Moreover, METTL7B depletion remarkably attenuated GBM cell proliferation. Mechanistically, METTL7B overexpression inhibited EGR1 expression in GBM cells. EGR1 knockdown rescued the inhibitory effect of METTL7B depletion on GBM cell proliferation. Meanwhile, METTL7B depletion arrested more GBM cells at the G0/G1, but fewer cells at the S phase, which EGR1 knockdown reversed these effects. Furthermore, tumorigenicity analysis revealed that METTL7B promotes tumor growth of GBM cells in vivo. METTL7B contributes to the malignant progression of GBM by inhibiting EGR1 expression. METTL7B and EGR1 may be utilized as the treatment targets for GBM therapy.

Egr1 Is Necessary for Forebrain Dopaminergic Signaling during Social Behavior

Finding the link between behaviors and their regulatory molecular pathways is a major obstacle in treating neuropsychiatric disorders. The immediate early gene (IEG) EGR1 is implicated in the etiology of neuropsychiatric disorders, and is linked to gene pathways associated with social behavior. Despite extensive knowledge of EGR1 gene regulation at the molecular level, it remains unclear how EGR1 deficits might affect the social component of these disorders. Here, we examined the social behavior of zebrafish with a mutation in the homologous gene egr1 Mutant fish exhibited reduced social approach and orienting, whereas other sensorimotor behaviors were unaffected. On a molecular level, expression of the dopaminergic biosynthetic enzyme, tyrosine hydroxylase (TH), was strongly decreased in TH-positive neurons of the anterior parvocellular preoptic nucleus. These neurons are connected with basal forebrain (BF) neurons associated with social behavior. Chemogenetic ablation of around 30% of TH-positive neurons in this preoptic region reduced social attraction to a similar extent as the egr1 mutation. These results demonstrate the requirement of Egr1 and dopamine signaling during social interactions, and identify novel circuitry underlying this behavior.

Effects of early life adversity on immediate early gene expression: Systematic review and 3-level meta-analysis of rodent studies

Early-life adversity (ELA) causes long-lasting structural and functional changes to the brain, rendering affected individuals vulnerable to the development of psychopathologies later in life. Immediate-early genes (IEGs) provide a potential marker for the observed alterations, bridging the gap between activity-regulated transcription and long-lasting effects on brain structure and function. Several heterogeneous studies have used IEGs to identify differences in cellular activity after ELA; systematically investigating the literature is therefore crucial for comprehensive conclusions. Here, we performed a systematic review on 39 pre-clinical studies in rodents to study the effects of ELA (alteration of maternal care) on IEG expression. Females and IEGs other than cFos were investigated in only a handful of publications. We meta-analyzed publications investigating specifically cFos expression. ELA increased cFos expression after an acute stressor only if the animals (control and ELA) had experienced additional hits. At rest, ELA increased cFos expression irrespective of other life events, suggesting that ELA creates a phenotype similar to naïve, acutely stressed animals. We present a conceptual theoretical framework to interpret the unexpected results. Overall, ELA likely alters IEG expression across the brain, especially in interaction with other negative life events. The present review highlights current knowledge gaps and provides guidance to aid the design of future studies.

Acidosis-Induced Regulation of Egr1 and Ccn1 In Vitro and in Experimental Tumours In Vivo

Extracellular acidosis is a characteristic of solid tumours, resulting from hypoxia-induced glycolytic metabolism as well as from the "Warburg effect" (aerobic glycolysis). The acidic environment has shown to affect functional tumour properties (proliferation, migration, invasion) and thus the aim of the study was to identify signalling mechanisms, mediating these pH-dependent effects. Therefore, the serum response factor (Srf) and the activation of the serum response element (SRE) by acidosis were analysed in AT-1 prostate carcinoma cells. Furthermore, the expression of downstream targets of this cascade, namely the early growth response 1 (Egr1), which seems to be involved in tumour proliferation, and the cellular communication network factor 1 (Ccn1), which both contain SRE in their promotor region were examined in two tumour cell lines. Extracellular acidification led to an upregulation of Srf and a functional activation of the SRE. Egr1 expression was increased by acidosis in AT-1 cells whereas hypoxia had a suppressive effect. In experimental tumours, in vivo Egr1 and Ccn1 were also found to be acidosis-dependent. Also, it turned out that pH regulated expression of Egr1 was followed by comparable changes of p21, which is an important regulator of the cell cycle.This study identifies the Srf-SRE signalling cascade and downstream Egr1 and Ccn1 to be acidosis-regulated in vitro and in vivo, potentially affecting tumour progression. Especially linked expression changes of Egr1 and p21 may mediate acidosis-induced effects on cell proliferation.

MICAL1 inhibits colorectal cancer cell migration and proliferation by regulating the EGR1/β-catenin signaling pathway

MICAL1 has been reported to be involved in the malignant processes of several types of cancer cells, however, the roles of MICAL1 in colorectal cancer (CRC) have not been well-characterized. This study aims to investigate the cellular functions and molecular mechanisms of MICAL1 in CRC cells. Here, we found that both mRNA and protein levels of MICAL1 were down-regulated in colorectal cancer tissues compared with matched adjacent non-tumor tissues, and the expression level of MICAL1 was correlated with the metastatic status of colorectal cancer. Importantly, overexpression of MICAL1 significantly inhibited colorectal cancer cell migration and growth, and increased the level of E-cadherin and Occludin, and suppressed the expression level of Vimentin and N-cadherin; while silencing of MICAL1 promoted CRC cell migration and enhanced EMT. In addition, MICAL1 overexpression significantly inhibited the proliferation and growth of CRC in vitro and in vivo. Moreover, RNA sequencing and bioinformatics analysis identified that MICAL1 was closely correlated with "cell migration", "cell cycle" and "β-catenin signaling" genesets. Mechanistically, overexpression of MICAL1 downregulated the mRNA level of EGR1 and β-catenin, decreased the protein level and nuclear translocation of β-catenin, and inhibited the transcriptions of β-catenin downstream targets, c-myc and cyclin D1. The ectopic expression of EGR1 or β-catenin can significantly block the MICAL1-mediated inhibitory effects. Collectively, MICAL1 is down-regulated in CRC, and plays an inhibitory role in the migration and growth of CRC cells by suppressing the ERG1/β-catenin signaling pathway.

Single molecule characterization of the binding kinetics of a transcription factor and its modulation by DNA sequence and methylation

The interaction of transcription factors with their response elements in DNA is emerging as a highly complex process, whose characterization requires measuring the full distribution of binding and dissociation times in a well-controlled assay. Here, we present a single-molecule assay that exploits the thermal fluctuations of a DNA hairpin to detect the association and dissociation of individual, unlabeled transcription factors. We demonstrate this new approach by following the binding of Egr1 to its consensus motif and the three binding sites found in the promoter of the Lhb gene, and find that both association and dissociation are modulated by the 9 bp core motif and the sequences around it. In addition, CpG methylation modulates the dissociation kinetics in a sequence and position-dependent manner, which can both stabilize or destabilize the complex. Together, our findings show how variations in sequence and methylation patterns synergistically extend the spectrum of a protein's binding properties, and demonstrate how the proposed approach can provide new insights on the function of transcription factors.

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.

Transcriptional Regulation of GDF15 by EGR1 Promotes Head and Neck Cancer Progression through a Positive Feedback Loop

Growth and differentiation factor 15 (GDF15), a divergent member of the transforming growth factor-β (TGF-β) superfamily, has been reported to be overexpressed in different kinds of cancer types. However, the function and mechanism of GDF15 in head and neck cancer (HNC) remains unclear. The Cancer Genome Atlas (TCGA) data show that the expression of GDF15 is significantly associated with tumor AJCC stage, lymph vascular invasion and tumor grade in HNC. In this study, we confirmed that knockdown of GDF15 attenuated: cell proliferation, migration and invasion via regulation of EMT through a canonical pathway; SMAD2/3 and noncanonical pathways; PI3K/AKT and MEK/ERK in HNC cell lines. Furthermore, we found that early growth response 1 (EGR1) was a transcription factor of GDF15. Interestingly, we also demonstrated that GDF15 could regulate the expression of EGR1, which meant a positive feedback loop occurred between these two factors. Moreover, combined inhibition of both GDF15 and EGR1 in a HNC mouse xenograft model showed significantly decreased tumor volume compared to inhibition of EGR1 or GDF15 alone. Our study showed that the GDF15–EGR1 signaling axis may be a good target in HNC patients.

DNA-PKcs kinase activity stabilizes the transcription factor Egr1 in activated immune cells

DNA-dependent protein kinase catalytic subunit (DNA-PKcs) is known primarily for its function in DNA double-stranded break repair and nonhomologous end joining (NHEJ). However, DNA-PKcs also has a critical yet undefined role in immunity impacting both myeloid and lymphoid cell lineages spurring interest in targeting DNA-PKcs for therapeutic strategies in immune-related diseases. To gain insight into the function of DNA-PKcs within immune cells, we performed a quantitative phosphoproteomic screen in T cells to identify phosphorylation targets of DNA-PKcs. Our results indicate that DNA-PKcs phosphorylates the transcription factor Egr1 (early growth response protein 1) at serine 301. Expression of Egr1 is induced early upon T cell activation and dictates T cell response by modulating expression of cytokines and key costimulatory molecules such as IL (interleukin) 2, IL6, IFNγ, and NFκB. Inhibition of DNA-PKcs by treatment with a DNA-PKcs specific inhibitor NU7441 or shRNA knockdown increased proteasomal degradation of Egr1. Mutation of serine 301 to alanine via CRISPR-Cas9 reduced EGR1 protein expression and decreased Egr1-dependent transcription of IL2 in activated T cells. Our findings identify DNA-PKcs as a critical intermediary link between T cell activation and T cell fate and a novel phosphosite involved in regulating Egr1 activity.

Irf1- and Egr1-activated transcription plays a key role in macrophage polarization: A multiomics sequencing study with partial validation

BACKGROUND

Macrophage polarization has a causal role in the pathogenesis and resolution of various clinical diseases. DNA-binding transcription factors (TFs) have been identified as essential factors during gene transcription. Better insight into the TFs that regulate macrophage polarization could provide novel therapeutic targets.

METHODS

IFN-γ (50 ng/mL) or IL4 (20 ng/mL) was utilized to stimulate bone marrow-derived macrophages from mice for 24 h for M1- and M2-polarized macrophage model construction, respectively. First, ATAC-seq (Assay for Targeting Accessible-Chromatin with high throughout sequencing) and motif analysis were conducted to identify potential transcription factors (TFs) involved in M1 and M2 macrophage polarization. Second, essential TFs were identified through RNA-seq, after which, their expression was compared between M0-polarized and M1/M2-polarized macrophages. Furthermore, a multiomic analysis of RNA-seq (siRNA knock down of the identified TFs), ChIP-seq and ATAC-seq was utilized to explore the TF-regulated molecular network. GO and KEGG analyses were used to expound the main functions of the TF-regulated molecular network. Finally, the top 5 TF-regulated genes were validated through flow cytometry, ELISA and qPCR. The cut-off values for high-throughput sequencing and qPCR were FDR < 0.05 and P < 0.05, respectively.

RESULTS

Compared with M0 macrophages, 10,771 and 4,848 peaks were identified by ATAC-seq during M1 and M2 macrophage polarization, respectively (FDR < 0.05). Fifty and 62 TF binding motifs were identified for the TFs that participate in M1 and M2 macrophage polarization, respectively. The most significantly highly expressed TFs in M1 and M2 macrophages were identified by RNA-seq as Irf1 and Egr1, with LogFC values of 3.2 and 2.8, respectively. Multiomic analyses further found that Irf1 regulated the transcription of 90 genes and that Egr1 regulated the transcription of 116 genes. The Irf1-regulated molecular network played a key role in the inflammatory response and viral defence of M1 macrophages, and 116 Egr1-regulated genes included anti-inflammatory and cell proliferation genes. Validation experiments indicated that IFN-γ-induced Gbp5, Nos2, CD86, Cxcl10 and Cxcl5 expression was significantly downregulated in siIrf1-BMDMs, and IL4-induced Itgax, Nipal1, Bhlhe40, CD206 and Ffar4 expression was significantly downregulated in siEgr1-BMDMs (P < 0.05).

CONCLUSIONS

Through multiomic analyses of epigenetic sequencing and RNA-seq with partial validation, the current study found that Irf1- and Egr1-induced transcription plays key roles in M1 and M2 macrophage polarization, respectively.

CIDEC silencing attenuates diabetic nephropathy via inhibiting apoptosis and promoting autophagy

OBJECTIVE

The role of cell death-inducing DFF45-like effector C (CIDEC) in insulin resistance has been established, and it is considered to be an important trigger factor for the progression of diabetic nephropathy (DN). We intend to explore whether CIDEC plays an important role in the regulation of DN and its potential mechanism.

METHODS

High-fat diet and low dose streptozotocin were used to establish type 2 diabetic rat model. We investigate the role of CIDEC in the pathogenesis and process of DN through histopathological analysis, western blot and gene silencing. Meanwhile, the effect of CIDEC on renal tubular epithelial cells stimulated by high glucose was also verified.

RESULTS

DM group exhibited glucose and lipid metabolic disturbance, with hypertrophy of kidneys, damaged renal function, increased apoptosis, decreased autophagy, glomerulosclerosis and interstitial fibrosis. CIDEC gene silencing improved metabolic disorder and insulin resistance, alleviated renal hypertrophy and renal function damage, decreased glomerular and tubular apoptosis, increased autophagy and inhibited renal fibrosis. At the cellular level, high glucose stimulation increased CIDEC expression in renal tubular epithelial cells, accompanied by increased apoptosis and decreased autophagy. CIDEC gene silencing can improve autophagy and reduce apoptosis. At the molecular level, CIDEC gene silencing also decreased the expression of early growth response factor (EGR)1 and increased the expression of adipose triglyceride lipase (ATGL).

CONCLUSION

CIDEC gene silencing may delay the progression of DN by restoring autophagy activity and inhibiting apoptosis with the participation of EGR1and ATGL.

Knockdown of plasmacytoma variant translocation 1 (PVT1) inhibits high glucose-induced proliferation and renal fibrosis in HRMCs by regulating miR-23b-3p/early growth response factor 1 (EGR1)

Long noncoding RNAs (lncRNAs) have been reported to play critical role in the development of diabetic nephropathy (DN). However, the effects and mechanism of plasmacytoma variant translocation 1 (PVT1) remain poorly understood. The expression of PVT1, miR-23b-3p, early growth response factor 1 (EGR1), Fibronectin (FN), Collagen IV (Col IV), alpha smooth muscle actin (α-SMA), E-cadherin, and vimentin, transforming growth factor (TGF)-β1 was examined by quantitative real-time polymerase chain reaction (qRT-PCR). Cell proliferation was assessed by Cell Counting-8 (CCK-8) assay. Western blot assay was conducted to measure the protein levels of FN, Col IV, E-cadherin, α-SMA, vimentin, TGF-β1, and EGR1. The interaction between miR-23b-3p and PVT1 or EGR1 was predicted by starBase or TargetScan and confirmed by the dual luciferase reporter assay. The oxidative stress factors were analyzed by corresponding kits. We found that the expression of PVT1 and EGR1 was increased and miR-23b-3p was decreased in serum samples of DN patients and HG-induced HRMCs. Knockdown of PVT1 significantly inhibited HG-induced proliferation, extracellular matrix (ECM) accumulation, epithelial-mesenchymal transition (EMT), and oxidative stress in HRMCs, while these effects were abated by inhibiting miR-23b-3p. In addition, EGR1 was confirmed as downstream target of miR-23b-3p and miR-23b-3p could specially bind to PVT1. Besides, downregulation of PVT1 inhibited the progression of DN partially via upregulating miR-23b-3p and downregulating EGR1. In conclusion, our results suggested that PVT1 knockdown suppressed DN progression though functioning as ceRNA of miR-23b-3p to regulate EGR1 expression in vitro, providing potential value for the treatment of DN.

Single cell epigenetic visualization assay

Characterization of the epigenetic status of individual cells remains a challenge. Current sequencing approaches have limited coverage, and it is difficult to assign an epigenetic status to the transcription state of individual gene alleles in the same cell. To address these limitations, a targeted microscopy-based epigenetic visualization assay (EVA) was developed for detection and quantification of epigenetic marks at genes of interest in single cells. The assay is based on an in situ biochemical reaction between an antibody-conjugated alkaline phosphatase bound to the epigenetic mark of interest, and a 5'-phosphorylated fluorophore-labeled DNA oligo tethered to a target gene by gene-specific oligonucleotides. When the epigenetic mark is present at the gene, phosphate group removal by the phosphatase protects the oligo from λ-exonuclease activity providing a quantitative fluorescent readout. We applied EVA to measure 5-methylcytosine (5mC) and H3K9Ac levels at different genes and the HIV-1 provirus in human cell lines. To link epigenetic marks to gene transcription, EVA was combined with RNA-FISH. Higher 5mC levels at the silenced compared to transcribed XIST gene alleles in female somatic cells validated this approach and demonstrated that EVA can be used to relate epigenetic marks to the transcription status of individual gene alleles.

Isoform-specific and signaling-dependent propagation of acute myeloid leukemia by Wilms tumor 1

Acute myeloid leukemia (AML) is caused by recurrent mutations in members of the gene regulatory and signaling machinery that control hematopoietic progenitor cell growth and differentiation. Here, we show that the transcription factor WT1 forms a major node in the rewired mutation-specific gene regulatory networks of multiple AML subtypes. WT1 is frequently either mutated or upregulated in AML, and its expression is predictive for relapse. The WT1 protein exists as multiple isoforms. For two main AML subtypes, we demonstrate that these isoforms exhibit differential patterns of binding and support contrasting biological activities, including enhanced proliferation. We also show that WT1 responds to oncogenic signaling and is part of a signaling-responsive transcription factor hub that controls AML growth. WT1 therefore plays a central and widespread role in AML biology.

Liraglutide Regulates the Kidney and Liver in Diabetic Nephropathy Rats through the miR-34a/SIRT1 Pathway

PURPOSE

To explore the regulatory effects of liraglutide on the kidney and liver through the miR-34a/SIRT1 pathway with related factors in diabetic nephropathy (DN) rats.

METHODS

DN rats were randomly divided into two groups (n = 10) and were injected with liraglutide or normal saline twice a day. The 24-hour urine microalbumin content and biochemical index levels were measured. qRT-PCR was performed to detect the expression of miR-34a in the kidney and liver tissues. The levels of SIRT1, HIF-1a, Egr-1, and TGF-β1 in kidney and liver tissues were determined using qRT-PCR, western blot, and immunohistochemistry. Electron microscopy and HE staining were used to observe the ultrastructure and pathological changes.

RESULTS

Liraglutide treatment in DN rats decreased blood glucose, 24-hour urine microalbumin, TC, TG, LDL-C, UA, Cr, UREA, ALT, and AST levels and increased the level of HDL-C (P < 0.05). Compared with the control group, the miR-34a levels were significantly decreased in kidney and liver tissues followed by liraglutide treatment (P < 0.05). The levels of SIRT1 in the liraglutide group are significantly higher than those in the control group with the kidney and liver tissues (P < 0.05). Conversely, the contents of HIF-1a, Egr-1, and TGF-β1 were significantly lower in the liraglutide group than in the control group (P < 0.05). Electron microscopy showed that the kidney of the liraglutide-treated group exhibited minor broadening of the mesangial areas, fewer deposits, and a well-organized foot process. HE staining revealed that the kidney of the liraglutide-treated rats had a more regular morphology of the glomerulus and Bowman sac cavity and lighter tubular edema. Additionally, the liraglutide-treated DN rats had a clear hepatic structure, a lower degree of steatosis, and mild inflammatory cell infiltration.

CONCLUSION

Liraglutide, through its effect on the miR-34a/SIRT1 pathway, may have a protective role in the kidney and liver of DN rats.

Adult-born neurons immature during learning are necessary for remote memory reconsolidation in rats

Memory reconsolidation, the process by which memories are again stabilized after being reactivated, has strengthened the idea that memory stabilization is a highly plastic process. To date, the molecular and cellular bases of reconsolidation have been extensively investigated particularly within the hippocampus. However, the role of adult neurogenesis in memory reconsolidation is unclear. Here, we combined functional imaging, retroviral and chemogenetic approaches in rats to tag and manipulate different populations of rat adult-born neurons. We find that both mature and immature adult-born neurons are activated by remote memory retrieval. However, only specific silencing of the adult-born neurons immature during learning impairs remote memory retrieval-induced reconsolidation. Hence, our findings show that adult-born neurons immature during learning are required for the maintenance and update of remote memory reconsolidation.