EGR3-HDAC6-IL-27 Axis Mediates Allergic Inflammation and Is Necessary for Tumorigenic Potential of Cancer Cells Enhanced by Allergic Inflammation-Promoted Cellular Interactions

Early growth response factor 3 regulates coronary atherosclerosis through the NF-κB signaling pathway and VEGF expression

AIM

The present study was conducted to measure the expression of early growth response factor 3 (Egr3), inflammatory cytokines (IL-1β, IL-6), vascular endothelial growth factor (VEGF) and NF-κB in patients with coronary artery disease (CAD) to investigate the relationships of these molecules and Egr3 gene expression.

METHODS

We recruited 132 CAD patients and 63 healthy individuals. The expression levels of Egr3, VEGF, p50 and p65 were measured by reverse transcription quantitative polymerase chain reaction and the levels of Egr3, IL-1β and IL-6 in patients serum and in human coronary artery endothelial cells (HCAECs) were measured by enzyme-linked immunosorbent assay (ELISAs) in CAD patients. HCAECs were treated with ox-LDL to establish an in vitro atherosclerosis model. An oil red O staining assay was used to assess the lipid droplet formation. A colloidal external lumen formed by Matrigel was used to test the migration of HCAECs. The expression of Egr3, VEGF and NF-κB was determined by Western blotting.

RESULTS

The levels of serum Egr3 and IL-6 in the severe stenosis group were greater than those in the mild stenosis group and controls (p < 0.05). The level of serum IL-1β in the severe stenosis group was greater than that in the control group (p < 0.05). Moreover, Egr3 expression was positively associated with IL-6 levels (r = 0.55, p < 0.001), IL-1β levels (r = 0.21, p = 0.004) and the Gensini score (r = 0.20, p = 0.02). We also found that Egr3 expression was significantly greater in CAD patients than that in controls. And its expression was highest in the mild patients. The expression of VEGF, P50 and P65 was also greater in CAD patients. In the in vitro experiment, we found that the inhibition of Egr3 expression significantly reduced the expression levels of p50, p65, IL-6 and CRP. Moreover, the inhibition of Egr3 expression significantly reduced the lipid droplet formation and decreased capability of lumen formation.

CONCLUSIONS

In the pathogenesis of atherosclerosis, Egr3 gene expression may induce the expression of inflammatory factors and lipid droplet formation and lumen formation, which could promote the atherosclerosis development.

Nur77 Mediates Anaphylaxis by Regulating miR-21a

Nur77 belongs to the NR4A subfamily of orphan nuclear hormone receptors. It has been shown to play important roles in metabolism, cancer progression, cellular differentiation, and the regulation of immune process. However, there has yet to be research reporting on the role of Nur77 in allergic inflammations such as anaphylaxis. This study aimed to identify molecules that could mediate allergic inflammations. To this end, we performed RNA sequencing analysis employing bone marrow-derived mast cells (BMMCs). Antigen (DNP-HSA) stimulation increased the expression levels of transcription factors such as Nr4a3 (NOR1), Nr4a1 (Nur77), and Nr4a2 (Nurr1). We focused our study on Nur77. Antigen stimulation increased the expression of Nur77 in a time- and dose-dependent manner in rat basophilic leukemia cells (RBL2H3). The downregulation of Nur77 prevented both antigen-induced increase in β-hexosaminidase activity as well as hallmarks of allergic reactions such as HDAC3, COX2, and MCP1 in RBL2H3 cells. Nur77 was necessary for both passive cutaneous anaphylaxis (PCA) and passive systemic anaphylaxis (PSA). TargetScan analysis predicted that miR-21a would be a negative regulator of Nur77. miR-21a mimic negatively regulated PCA and PSA by inhibiting the hallmarks of allergic reactions. ChIP assays showed that c-JUN could bind to the promoter sequences of Nur77. Antigen stimulation increased the expression of c-JUN in RBL2H3 cells. Altogether, our findings demonstrate the regulatory role played by Nur77-miR-21a loop in allergic inflammations such as anaphylaxis, making this the first report to present the role played by Nur77 in an allergic inflammation. Our results suggest that Nur77 and miR-21 might serve as targets for developing anti-allergy drugs.

EGR3 reduces podocyte inflammatory damage in obesity related glomerulopathy by inhibiting the PRMT1pSTAT3 pathway

OBJECTIVES

Obesity related glomerulopathy (ORG) is induced by obesity, but the pathogenesis remains unclear. This study aims to investigate the expression of early growth response protein 3 (EGR3) in the renal cortex tissues of ORG patients and high-fat diet-induced obese mice, and to further explore the molecular mechanism of EGR3 in inhibiting palmitic acid (PA) induced human podocyte inflammatory damage.

METHODS

Renal cortex tissues were collected from ORG patients (n=6) who have been excluded from kidney damage caused by other diseases and confirmed by histopathology, and from obese mice induced by high-fat diet (n=10). Human and mouse podocytes were intervened with 150 μmol/L PA for 48 hours. EGR3 was overexpressed or silenced in human podocytes. Enzyme linked immunosorbent assay (ELISA) was used to detcet the levels of interleukin-6 (IL-6) and interleukin-1β (IL-1β). Real-time RT-PCR was used to detect the mRNA expressions of EGR3, podocytes molecular markers nephrosis 1 (NPHS1), nephrosis 2 (NPHS2), podocalyxin (PODXL), and podoplanin (PDPN). RNA-seq was performed to detect differentially expressed genes (DEGs) after human podocytes overexpressing EGR3 and treated with 150 μmol/L PA compared with the control group. Co-immunoprecipitation (Co-IP) combined with liquid chromatography tandem mass spectrometry (LC-MS) was used to detect potential interacting proteins of EGR3 and the intersected with the RNA-seq results. Co-IP confirmed the interaction between EGR3 and protein arginine methyltransferases 1 (PRMT1), after silencing EGR3 and PRMT1 inhibitor intervention, the secretion of IL-6 and IL-1β in PA-induced podocytes was detected. Western blotting was used to detect the expression of phosphorylated signal transducer and activator of transcription 3 (p-STAT3) after overexpression or silencing of EGR3.

RESULTS

EGR3 was significantly upregulated in renal cortex tissues of ORG patients and high-fat diet-induced obese mice (both P<0.01). In addition, after treating with 150 μmol/L PA for 48 hours, the expression of EGR3 in human and mouse podocytes was significantly upregulated (both P<0.05). Overexpression or silencing of EGR3 in human podocytes inhibited or promoted the secretion of IL-6 and IL-1β in the cell culture supernatant after PA intervention, respectively, and upregulated or downregulated the expression of NPHS1, PODXL, NPHS2,and PDPN (all P<0.05). RNA-seq showed a total of 988 DEGs, and Co-IP+LC-MS identified a total of 238 proteins that may interact with EGR3. Co-IP confirmed that PRMT1 was an interacting protein with EGR3. Furthermore, PRMT1 inhibitors could partially reduce PA-induced IL-6 and IL-1β secretion after EGR3 silencing in human podocytes (both P<0.05). Overexpression or silencing of EGR3 negatively regulated the expression of PRMT1 and p-STAT3.

CONCLUSIONS

EGR3 may reduce ORG podocyte inflammatory damage by inhibiting the PRMT1/p-STAT3 pathway.

Shift work promotes adipogenesis via cortisol-dependent downregulation of EGR3-HDAC6 pathway

The disruption of circadian rhythms caused by long-term shift work can cause metabolic diseases such as obesity. Early growth response 3 (EGR3) is a member of early growth response (EGR) family, which is involved in several cellular responses, had been reported as a circadian rhythm gene in suprachiasmatic nucleus. In this research, EGR3 was found to be widely expressed in the different tissue of human and mice, and downregulated in adipose tissue of obese subjects and high-fat diet mice. Moreover, EGR3 was found negatively regulated by cortisol. In addition, EGR3 is a key negative modulator of hADSCs and 3T3-L1 adipogenesis via regulating HDAC6, which is a downstream target gene of EGR3 and a negative regulator of adipogenesis and lipogenesis. These findings may explain how circadian rhythm disorder induced by shift works can cause obesity. Our study revealed a potential therapeutic target to alleviate metabolic disorders in shift workers and may provide better health guidance to shift workers.

HDAC6-selective inhibitor CAY10603 ameliorates cigarette smoke-induced small airway remodeling by regulating epithelial barrier dysfunction and reversing

BACKGROUND

Small airway remodelling is a vital characteristic of chronic obstructive pulmonary disease (COPD), which is mainly caused by epithelial barrier dysfunction and epithelial-mesenchymal transition (EMT). Recent studies have indicated that histone deacetylase 6 (HDAC6) plays an important role in the dysregulation of epithelial function. In this study, we investigated the therapeutic effects and underlying mechanisms of an inhibitor with high selectivity for HDAC6 in COPD.

METHODS

Cigarette smoke (CS) exposure was used to establish a CS-induced COPD mouse model. CAY10603 at doses of 2.5 and 10 mg/kg was injected intraperitoneally on alternate days. The protective effects of CAY10603 against CS-induced emphysema, epithelial barrier function and small airway remodeling were evaluated using hematoxylin and eosin (H&E) staining, Masson's trichrome staining, immunohistochemical staining, and western blot. The human lung bronchial epithelial cell line (HBE) was used to elucidate the underlying molecular mechanism of action of CAY10603.

RESULTS

HDAC6 levels in the lung homogenates of CS-exposed mice were higher than that those in control mice. Compared to the CS group, the mean linear intercept (MLI) of the CAY10603 treatment group decreased and the mean alveolar number (MAN)increased. Collagen deposition was reduced in groups treated with CAY10603. The expression of α-SMA was markedly upregulated in the CS group, which was reversed by CAY10603 treatment. Conversely, E-cadherin expression in the CS group was further downregulated, which was reversed by CAY10603 treatment. CAY10603 affects the tight junction protein expression of ZO-1 and occludin. ZO-1 and occludin expression were markedly downregulated in the CS group. After CAY10603treatment, the protein expression level of ZO-1 and occludin increased significantly. In HBE cells, Cigarette smoke extract (CSE) increased HDAC6 levels. CAY10603 significantly attenuated the release of TGF-β1 induced by CSE. CAY10603 significantly increased the E-cadherin levels in TGF-β1 treated HBE cells, while concurrently attenuated α-SMA expression. This effect was achieved through the suppression of Smad2 and Smad3 phosphorylation. CAY10603 also inhibited TGF-β1 induced cell migration.

CONCLUSIONS

These findings suggested that CAY10603 inhibited CS induced small airway remodelling by regulating epithelial barrier dysfunction and reversing EMT via the TGF-β1/Smad2/3 signalling pathway.

HDAC6-MYCN-CXCL3 axis mediates allergic inflammation and is necessary for allergic inflammation-promoted cellular interactions

Histone deacetylase 6 (HDAC6) has been shown to play an important role in allergic inflammation. This study hypothesized that novel downstream targets of HDAC6 would mediate allergic inflammation. Experiments employing HDAC6 knock out C57BL/6 mice showed that HDAC6 mediated passive cutaneous anaphylaxis (PCA) and passive systemic anaphylaxis (PSA). Antigen stimulation increased expression of N-myc (MYCN) and CXCL3 in an HDAC6-dependent manner in the bone marrow-derived mast cells. MYCN and CXCL3 were necessary for both PCA and PSA. The role of early growth response 3 (EGR3) in the regulation of HDAC6 expression has been reported. ChIP assays showed EGR3 as a direct regulator of MYCN. miR-34a-5p was predicted to be a negative regulator of MYCN. Luciferase activity assays showed miR-34a-5p as a direct regulator of MYCN. miR-34a-5p mimic negatively regulated PCA and PSA. MYCN decreased miR-34a-5p expression in antigen-stimulated rat basophilic leukemia cells (RBL2H3). MYCN was shown to bind to the promoter sequence of CXCL3. In an IgE-independent manner, recombinant CXCL3 protein increased expression of HDAC6, MYCN, and β-hexosaminidase activity in RBL2H3 cells. Mouse recombinant CXCL3 protein enhanced the angiogenic potential of the culture medium of RBL2H3. CXCL3 was necessary for the enhanced angiogenic potential of the culture medium of antigen-stimulated RBL2H3. The culture medium of RBL2H3 was able to induce M2 macrophage polarization in a CXCL3-dependent manner. Recombinant CXCL3 protein also increased the expression of markers of M2 macrophage. Thus, the identification of the novel role of HDAC6-MYCN-CXCL3 axis can help better understand the pathogenesis of anaphylaxis.

C6 Ceramide Inhibits Canine Mammary Cancer Growth and Metastasis by Targeting EGR3 through JAK1/STAT3 Signaling

Cancer is the leading cause of death in both humans and companion animals. Canine mammary tumor is an important disease with a high incidence and metastasis rate, and its poor prognosis remains a serious clinical challenge. C6 ceramide is a short-chain sphingolipid metabolite with powerful potential as a tumor suppressor. However, the specific impact of C6 ceramide on canine mammary cancer remains unclear. However, the effects of C6 ceramide in canine mammary cancer are still unclear. Therefore, we investigated the role of C6 ceramide in the progress of canine mammary cancer and explored its potential mechanism. C6 ceramide inhibited cell growth by regulating the cell cycle without involving apoptosis. Additionally, C6 ceramide inhibited the migration and invasion of CHMp cells. In vivo, C6 ceramide decreased tumor growth and metastasis in the lungs without side effects. Further investigation found that the knockdown of EGR3 expression led to a noticeable increase in proliferation and migration by upregulating the expressions of pJAK1 and pSTAT3, thus activating the JAK1/STAT3 signaling pathway. In conclusion, C6 ceramide inhibits canine mammary cancer growth and metastasis by targeting EGR3 through the regulation of the JAK1/STAT3 signaling pathway. This study implicates the mechanisms underlying the anti-tumor activity of C6 ceramide and demonstrates the potential of EGR3 as a novel target for treating canine mammary cancer.

EGR3 and estrone are involved in the tamoxifen resistance and progression of breast cancer

BACKGROUND

Tamoxifen (Tam) is an effective treatment for estrogen receptor (ER) positive breast cancer. However, a significant proportion of patients develop resistance under treatment, presenting a therapeutic challenge. The study aims to determine the role of early growth response protein (EGR) 3 in tamoxifen resistance (TamR) and elucidate its molecular mechanism.

METHODS

TamR cell models were established and NGS was used to screening signaling alternation. Western blot and qRT-PCR were used to analysis the expression of ERα, EGR3, MCL1 and factors associated with apoptosis. CCK8, colony formation and apoptosis assay were used to analysis resistance to Tam. Immunofluorescence, chromatin immunoprecipitation, and dual luciferase assays were used to investigate mechanism of regulation.

RESULTS

We observed that EGR3, a deeply rooted ERα response factor, showed increased upregulation in response to both estrone (E1) and Tam in TamR cells with elevated level of E1 and ERα expression, indicating a potential connection between EGR3 and TamR. Mechanically, manipulating EGR3 expression revealed that it imparted resistance to Tam through increased expression of the downstream molecule MCL1 (apoptosis suppressor gene) that it regulated. Mechanismly, EGR3 directly binds to the promoter of the anti-apoptotic factor MCL1 gene, facilitating its transcription. Furthermore, apoptosis assays revealed that E1 reduces Tam induced apoptosis by upregulating EGR3 expression. Importantly, clinical public database confirmed the high expression of EGR3 in breast cancer tissue and in Tam-treated patients.

CONCLUSIONS

These findings shed light on the novel estrogen/EGR3/MCL1 axis and its role in inducing TamR in ER positive breast cancer. EGR3 emerges as a promising target to overcome TamR. The elucidation of this mechanism holds potential for the development of new therapeutic modalities to overcome endocrine therapy resistance in clinical settings.

Intrafusal-fiber LRP4 for muscle spindle formation and maintenance in adult and aged animals

Proprioception is sensed by muscle spindles for precise locomotion and body posture. Unlike the neuromuscular junction (NMJ) for muscle contraction which has been well studied, mechanisms of spindle formation are not well understood. Here we show that sensory nerve terminals are disrupted by the mutation of Lrp4, a gene required for NMJ formation; inducible knockout of Lrp4 in adult mice impairs sensory synapses and movement coordination, suggesting that LRP4 is required for spindle formation and maintenance. LRP4 is critical to the expression of Egr3 during development; in adult mice, it interacts in trans with APP and APLP2 on sensory terminals. Finally, spindle sensory endings and function are impaired in aged mice, deficits that could be diminished by LRP4 expression. These observations uncovered LRP4 as an unexpected regulator of muscle spindle formation and maintenance in adult and aged animals and shed light on potential pathological mechanisms of abnormal muscle proprioception.

Functional mechanism of EGR3 in cerebral ischemia/reperfusion injury in rats by modulating transcription of pri-miR-146a/146b to miR-146 and suppressing SORT1 expression

OBJECTIVE

EGR3 is implicated in angiogenesis in rats with cerebral ischemia/reperfusion injury (CIRI). This research aimed to explore the effect and in vivo and ex vivo mechanisms of EGR3 in CIRI.

METHODS

CIRI rat models were established via middle cerebral artery occlusion. Cell models were established via oxygen-glucose deprivation/reoxygenation (OGD/R). Brain injury was assessed by neurological scoring, HE, and TTC staining. Inflammatory factors and oxidative stress markers were measured using corresponding kits. Mitochondrial membrane potential and mitochondrial respiration were examined by flow cytometry and respirometry. EGR3-miR-146 network was predicted on TransmiR v2.0 database. Target genes of miR-146 were screened on Starbase, Targetscan, and miRDB databases. miR-146 expression was determined by RT-qPCR. Levels of EGR3 and SORT1 were determined by Western blot. Binding relationships among EGR3, miR-146, and SORT1 were validated by dual-luciferase assay. EGR3, miR-146, and SORT1 levels were altered by injection or cell transfection to observe their functions.

RESULTS

EGR3 was poorly-expressed in CIRI rats and OGD/R-induced neurons. EGR3 overexpression reduced inflammatory factor levels and attenuated oxidative stress and mitochondrial injury in CIRI rats and OGD/R-induced neurons. EGR3 bound to miR-146b promoter region. EGR3 promoted pri-miR-146a/146b processing and stimulated miR-146 transcription. miR-146 overexpression ameliorated oxidative stress and mitochondrial injury and miR-146 downregulation abolished the effect of EGR3 overexpression in vitro. miR-146 targeted SORT1. SORT1 overexpression invalidated the protective function of miR-146 overexpression on oxidative stress and mitochondrial injury in vitro.

CONCLUSION

EGR3 protected against CIRI by mitigating oxidative stress and mitochondrial injury via the miR-146/SORT1 axis.

The Crosstalk between FcεRI and Sphingosine Signaling in Allergic Inflammation

Sphingolipid molecules have recently attracted attention as signaling molecules in allergic inflammation diseases. Sphingosine-1-phosphate (S1P) is synthesized by two isoforms of sphingosine kinases (SPHK 1 and SPHK2) and is known to be involved in various cellular processes. S1P levels reportedly increase in allergic inflammatory diseases, such as asthma and anaphylaxis. FcεRI signaling is necessary for allergic inflammation as it can activate the SPHKs and increase the S1P level; once S1P is secreted, it can bind to the S1P receptors (S1PRs). The role of S1P signaling in various allergic diseases is discussed. Increased levels of S1P are positively associated with asthma and anaphylaxis. S1P can either induce or suppress allergic skin diseases in a context-dependent manner. The crosstalk between FcεRI and S1P/SPHK/S1PRs is discussed. The roles of the microRNAs that regulate the expression of the components of S1P signaling in allergic inflammatory diseases are also discussed. Various reports suggest the role of S1P in FcεRI-mediated mast cell (MC) activation. Thus, S1P/SPHK/S1PRs signaling can be the target for developing anti-allergy drugs.

The Landscape of Early Growth Response Family Members 1-4 in Hepatocellular Carcinoma: Their Biological Roles and Diagnostic Utility

The incidence of hepatocellular carcinoma (HCC), which is one of the most frequent types of cancer seen all over the world, is steadily growing from year to year. EGR genes are members of the early growth response (EGR) gene family. It has been shown that EGR genes play an increasingly essential role in the development of tumors and the progression of numerous malignancies. However, the possible diagnostic and prognostic roles of EGR genes in HCC have only been examined in a limited number of studies. Expression and methylation data on EGR family members were obtained from TCGA datasets. The prognostic values of EGR members were studied. Additionally, the correlations of EGR members with immune cells were assessed through the single-sample gene set enrichment analysis (ssGSEA). In this study, we found that the expression of EGR1, EGR2, EGR3, and EGR4 was distinctly decreased in HCC specimens compared with nontumor specimens. ROC assays confirmed that they have a strong ability in screening HCC specimens from nontumor specimens. According to the findings of Pearson's correlation, EGR1, EGR2, EGR3, and EGR4 were found to have a negative association with the methylation level. Survival study revealed that EGR1, EGR2, and EGR3 were associated with the clinical outcome of HCC patients. Immune cell enrichment analysis demonstrated that the expressions of all EGR members were positively related to the levels of most types of immune cells, such as macrophages, NK cells, B cells, T cells, eosinophils, and CD8 T cells. Overall, the current work demonstrated the expression mode and prognostic value of EGR members in HCC in a comprehensive manner, offering insights for further research of the EGR family as possible clinical biomarkers in HCC.