Egr-1 upregulates Siva-1 expression and induces cardiac fibroblast apoptosis

Early growth response-1: Key mediators of cell death and novel targets for cardiovascular disease therapy

Significance

Cardiovascular diseases are seen to be a primary cause of death, and their prevalence has significantly increased across the globe in the past few years. Several studies have shown that cell death is closely linked to the pathogenesis of cardiovascular diseases. Furthermore, many molecular and cellular mechanisms are involved in the pathogenesis of the cardiac cell death mechanism. One of the factors that played a vital role in the pathogenesis of cardiac cell death mechanisms included the early growth response-1 (Egr-1) factor.

Recent Advances

Studies have shown that abnormal Egr-1 expression is linked to different animal and human disorders like heart failure and myocardial infarction. The biosynthesis of Egr-1 regulates its activity. Egr-1 can be triggered by many factors such as serum, cytokines, hormones, growth factors, endotoxins, mechanical injury, hypoxia, and shear stress. It also displays a pro-apoptotic effect on cardiac cells, under varying stress conditions. EGR1 mediates a broad range of biological responses to oxidative stress and cell death by combining the acute changes occurring in the cellular environment with sustained changes in gene expression.

Future Directions

The primary regulatory role played by the Egr-1-targeting DNAzymes, microRNAs, and oligonucleotide decoy strategies in cardiovascular diseases were identified to provide a reference to identify novel therapeutic targets for cardiovascular diseases.

Mice with double knockout of Egr-1 and RCAN1 exhibit reduced inflammation during Pseudomonas aeruginosa lung infection

Pseudomonas aeruginosa represents one of the major opportunistic pathogens, which causes nosocomial infections in immunocompromised individuals. The molecular mechanisms controlling the host immune response to P. aeruginosa infections are not completely understood. In our previous study, early growth response 1 (Egr-1) and regulator of calcineurin 1 (RCAN1) were found to positively and negatively regulate the inflammatory responses, respectively, during P. aeruginosa pulmonary infection, and both of them had an impact on activating NF-κB pathway. Herein, we examined the inflammatory responses of Egr-1/RCAN1 double knockout mice using a mouse model of P. aeruginosa acute pneumonia. As a result, the Egr-1/RCAN1 double knockout mice showed reduced production of proinflammatory cytokines (IL-1β, IL-6, TNF and MIP-2), diminished inflammatory cell infiltration and decreased mortality, which were similar to those of Egr-1-deficienct mice but different from those of RCAN1-deficient mice. In vitro studies demonstrated that Egr-1 mRNA transcription preceded RCAN1 isoform 4 (RCAN1.4) mRNA transcription in macrophages, and the macrophages with Egr-1 deficiency exhibited decreased RCAN1.4 mRNA levels upon P. aeruginosa LPS stimulation. Moreover, Egr-1/RCAN1 double-deficient macrophages had reduced NF-κB activation compared to RCAN1-deficient macrophages. Taken together, Egr-1 predominates over RCAN1 in regulating inflammation during P. aeruginosa acute lung infection, which influences RCAN1.4 gene expression.

Expression profiling analysis reveals key microRNA-mRNA interactions in patients with transposition of the great arteries and systemic left and right ventricles

Background

Patients with transposition of the great arteries (TGA) have different connected systemic chambers and this determines the long-term morbidities and survival. Limited findings have been reported to systematically identify miRNA and mRNA expression levels in such cohorts of patients. In this study, we aimed to characterize miRNAs, mRNAs, and miRNA-mRNA interaction networks in patients with TGA, with a systemic left (LV) and right ventricle (RV).

Materials and methods

Large panel of human miRNA and mRNA microarrays were conducted to determine the genome-wide expression profiles in the blood of 16 TGA-RV patients, 16 TGA-LV patients, and 16 age and gender-matched controls. Using real-time quantitative PCR (RT-qPCR), the differential expression level of a single miRNA was validated. Enrichment analyses of altered miRNA and mRNA expression levels were identified using bioinformatics tools.

Results

Altered miRNA and mRNA expression levels were observed between TGA-RV and TGA-LV patients, together or separated, compared to controls. Among the deregulated miRNAs and mRNAs, 39 and 101 miRNAs were identified as significantly differentially expressed in patients with TGA (both TGA-RV and TGA-LV) and TGA-RV, when compared to matched controls. Furthermore, 51 miRNAs were identified as significantly differentially expressed in patients with TGA-RV when compared to patients with TGA-LV. RT-qPCR relative expression level was highly consistent with microarray analysis results. Similarly, 36 and 164 mRNAs were identified as significantly differentially expressed in patients with TGA (both TGA-RV and TGA-LV) and TGA-RV, when compared to matched controls. Additionally, miR-140-3p showed a higher expression level in patients with overt heart failure (FC = 1.54; P = 0.001) and miR-502-3p showed a higher expression level in patients died due to cardiac death (FC = 1.41; P = 0.011). Integrative analysis resulted in 21 and 23 target genes with higher and lower expression levels, respectively (r ≥ 0.50 and P < 0.05). These target genes (i.e., 21 and 23 target genes) showed an inverse direction of regulation with miRNA and exhibited a miRNA binding site position within the 3'UTR of the target gene.

Conclusion

Our findings provide new insights into a potential molecular biomarker(s) for patients with TGA that may guide better risk stratification and the development of novel targeting therapies. Future studies are needed to investigate the potential significance of miRNAs and mRNAs in TGA-related cardiovascular diseases.

miR‑let‑7c‑3p targeting on Egr‑1 contributes to the committed differentiation of leukemia cells into monocyte/macrophages

In preliminary experiments, it was found that the expression of early growth response-1 (Egr-1) was upregulated during the committed differentiation of leukemia cells into monocytes/macrophages. The cross-analysis of gene chip detection and database prediction indicated that Egr-1 was associated with upstream microRNA (miR)-let-7c-3p, thus the present study focused on the role of the miR-let-7c-3p/Egr-1 signaling axis in the committed differentiation of leukemia cells into monocytes/macrophages. Phorbol 12-myristate 13-acetate (PMA) was used to induce the directed differentiation of human K562 leukemia cells into monocytes/macrophages and the differentiation of K562 leukemia cells was determined by cell morphology observation and expression of differentiation antigens CD11b and CD14 by flow cytometry. The expression levels of Egr-1 and miR-let-7c-3p were detected by reverse transcription-quantitative PCR and the protein expression of Egr-1 was detected by western blotting. The effect of Egr-1 on the differentiation of K562 cells was detected by short interfering (si)RNA interference assay. A dual-luciferase reporter assay was used to detect target binding of miR-let-7c-3p on the 3′UTR of Egr-1. Cell transfection of miR-let-7c-3p mimics and inhibitors was used to modulate the expression of miR-let-7c-3p, as indicated by RT-qPCR assays. Western blotting was also used to examine the effect of miR-let-7c-3p on Egr-1 expression. The PMA-induced differentiation of K562 cells was transfected with miR-let-7c-3p and the expression of differentiation antigen was detected by flow cytometry. A differentiation model of K562 leukemia cells into monocytes/macrophages was induced by PMA, which was indicated by morphological observations and upregulation of CD11b and CD14 antigens. The gene or protein expression of Egr-1 was significantly higher compared with that of the control group, while the expression of miR-let-7c-3p was significantly lower compared with that of the control group. siRNA interference experiments showed that the expression of cell differentiation antigen CD14 in the 100 µg/ml PMA + si-Egr-1 group was significantly lower compared with that in the 100 µg/ml PMA + si-ctrl group. The dual luciferase reporter gene results showed that the luciferase activity of the co-transfected mimic and Egr-1 WT groups was significantly lower than that of the NC control group, while the luciferase activity of the co-transfected mimic and Egr-1 MUT groups was comparable to that of the NC control group. Therefore, the dual-luciferase reporter gene assay confirmed that miR-let-7c-3p can target Egr-1. Western blotting showed that the expression of Egr-1 following transfection with miR-let-7c-3p inhibitor was significantly higher compared with that of the negative control and the expression of Egr-1 after transfection with miR-let-7c-3p mimic was significantly lower than that of the negative control. Following exposure to PMA, the expressions of CD11b and CD14 in the miR-let-7c-3p inhibitor group were significantly higher than those in the miR-let-7c-3p NC group, as indicated by CD11b and CD14 respectively. In conclusion, miR-let-7c-3p could bind to the 3′UTR of Egr-1 and negatively regulated Egr-1 expression. The miR-let-7c-3p/Egr-1 signaling axis was closely associated with the committed differentiation of K562 cells from leukemia cells to monocytes/macrophages.

Signaling Pathways Involved in Myocardial Ischemia-Reperfusion Injury and Cardioprotection: A Systematic Review of Transcriptomic Studies in Sus scrofa

Myocardial damage in acute myocardial infarctions (AMI) is primarily the result of ischemia−reperfusion injury (IRI). Recognizing the timing of transcriptional events and their modulation by cardioprotective strategies is critical to address the pathophysiology of myocardial IRI. Despite the relevance of pigs for translational studies of AMI, only a few have identified how transcriptomic changes shape cellular signaling pathways in response to injury. We systematically reviewed transcriptomic studies of myocardial IRI and cardioprotection in Sus scrofa. Gene expression datasets were analyzed for significantly enriched terms using the Enrichr analysis tool, and statistically significant results (adjusted p-values of <0.05) for Signaling Pathways, Transcription Factors, Molecular Functions, and Biological Processes were compared between eligible studies to describe how these dynamic changes transform the myocardium from an injured and inflamed tissue into a scar. Then, we address how cardioprotective interventions distinctly modulate the myocardial transcriptome and discuss the implications of uncovering gene regulatory networks for cardiovascular pathologies and translational applications.

FAIM-L - SIVA-1: Two Modulators of XIAP in Non-Apoptotic Caspase Function

Apoptosis is crucial for the correct development of the nervous system. In adulthood, the same protein machinery involved in programmed cell death can control neuronal adaptiveness through modulation of synaptic pruning and synaptic plasticity processes. Caspases are the main executioners in these molecular pathways, and their strict regulation is essential to perform neuronal remodeling preserving cell survival. FAIM-L and SIVA-1 are regulators of caspase activation. In this review we will focus on FAIM-L and SIVA-1 as two functional antagonists that modulate non-apoptotic caspase activity in neurons. Their participation in long-term depression and neurite pruning will be described in base of the latest studies performed. In addition, the association of FAIM-L non-apoptotic functions with the neurodegeneration process will be reviewed.

EGR1 interacts with DNMT3L to inhibit the transcription of miR-195 and plays an anti-apoptotic role in the development of gastric cancer

EGR1 regulates the expression of its downstream target genes and may exert different biological effects in different tumours. We found that the expression of EGR1 was increased in gastric cancer (GC), and silencing the expression of EGR1 promoted the apoptosis of GC cells. Moreover, overexpression of EGR1 repressed the apoptosis of GC cells. Bioinformatics analysis showed that EGR1 had binding sites at the upstream promoter region of miR‐195; ChIP assays were applied to determine EGR1 occupancy of the miR‐195 promoter. The RT‐PCR results showed that EGR1 suppressed the expression of miR‐195. The mechanism by which EGR1 acts as a transcriptional repressor is still unclear. Bioinformatics analysis showed that EGR1 may interact with DNMT3L. We confirmed that EGR1 and DNMT3L formed a complex, and EGR1 was an important player in the transcriptional control of miR‐195. Overexpression of miR‐195 inhibited proliferation and promoted apoptosis in GC cells. We found a well‐matched miR‐195 binding site at the AKT3 3′‐UTR. Double luciferase reporter assays showed that AKT3 was a target of miR‐195, and silencing AKT3 repressed cell proliferation and promoted apoptosis. Our results indicated EGR1 may interact with DNMT3L to inhibit the miR‐195‐AKT3 axis and regulate the GC cell apoptosis.

Transcriptome sequencing of lncRNA, miRNA, mRNA and interaction network constructing in coronary heart disease

Background

Non-coding RNA has been shown to participate in numerous biological and pathological processes and has attracted increasing attention in recent years. Recent studies have demonstrated that long non-coding RNA and micro RNA can interact through various mechanisms to regulate mRNA. Yet the gene-gene interaction has not been investigated in coronary heart disease (CHD).

Methods

High throughput sequencing were used to identify differentially expressed (DE) lncRNA, miRNA, and mRNA profiles between CHD and healthy control. Gene Oncology (GO), KEGG enrichment analysis were performed. Gene-gene interaction network were constructed and pivotal genes were screened out. Lentivirus-induced shRNA infection and qRT-PCR were performed to validated the gene-gene interactions.

Results

A total of 62 lncRNAs, 332 miRNAs and 366 mRNAs were differentially expressed between CHD and healthy control. GO and KEGG analysis show that immune related molecular mechanisms and biological processes play a role in CHD. The gene-gene interaction network were constructed and visualized based on Pearson correlation coefficients and starBase database. 6 miRNAs in the network were significantly correlated to left ventricular ejection fraction, total choleterol and homocysteine. 2 lncRNAs (CTA-384D8.35 and CTB-114C7.4 (refseq entry LOC100128059)), 1 miRNA (miR-4497), and 1 mRNA (NR4A1) were the pivotal genes. Lentivirus-induced shRNA infection and qRT-PCR had validated the pivotal gene-gene interactions.

Conclusions

These results have shown the potential of lncRNA, miRNA, and mRNA as clinical biomarkers and in elucidating pathological mechanisms of CHD from a transcriptomic perspective.

Electronic supplementary material

The online version of this article (10.1186/s12920-019-0570-z) contains supplementary material, which is available to authorized users.

Siva plays a critical role in mouse embryonic development

The Siva protein, named after the Hindu God of Destruction, plays important roles in apoptosis in various contexts, including downstream of death receptor activation or p53 tumor suppressor engagement. The function of Siva in organismal development and homeostasis, however, has remained uncharacterized. Here, we generate Siva knockout mice to characterize the physiological function of Siva in vivo. Interestingly, we find that Siva deficiency causes early embryonic lethality accompanied by multiple phenotypes, including developmental delay, abnormal neural tube closure, and defective placenta and yolk sac formation. Examination of Siva expression during embryogenesis shows that Siva is expressed in both embryonic and extra-embryonic tissues, including within the mesoderm, which may explain the vascular defects observed in the placenta and yolk sac. The embryonic phenotypes caused by Siva loss are not rescued by p53 deficiency, nor do they resemble those of p53 null embryos, suggesting that the embryonic function of Siva is not related to the p53 pathway. Moreover, loss of the Ripk3 necroptosis protein does not rescue the observed lethality or developmental defects, suggesting that Siva may play a non-apoptotic role in development. Collectively, these studies reveal a key role for Siva in proper embryonic development.

Placental epigenetics for evaluation of fetal congenital heart defects: Ventricular Septal Defect (VSD)

Ventricular Septal Defect (VSD), the most common congenital heart defect, is characterized by a hole in the septum between the right and left ventricles. The pathogenesis of VSD is unknown in most clinical cases. There is a paucity of data relevant to epigenetic changes in VSD. The placenta is a fetal tissue crucial in cardiac development and a potentially useful surrogate for evaluating the development of heart tissue. To understand epigenetic mechanisms that may play a role in the development of VSD, genome-wide DNA methylation assay on placentas of 8 term subjects with isolated VSD and no known or suspected genetic syndromes and 10 unaffected controls was performed using the Illumina HumanMethylation450 BeadChip assay. We identified a total of 80 highly accurate potential CpGs in 80 genes for detection of VSD; area under the receiver operating characteristic curve (AUC ROC) 1.0 with significant 95% CI (FDR) p-values < 0.05 for each individual locus. The biological processes and functions for many of these differentially methylated genes are previously known to be associated with heart development or disease, including cardiac ventricle development (HEY2, ISL1), heart looping (SRF), cardiac muscle cell differentiation (ACTC1, HEY2), cardiac septum development (ISL1), heart morphogenesis (SRF, HEY2, ISL1, HEYL), Notch signaling pathway (HEY2, HEYL), cardiac chamber development (ISL1), and cardiac muscle tissue development (ACTC1, ISL1). In addition, we identified 8 microRNAs that have the potential to be biomarkers for the detection of VSD including: miR-191, miR-548F1, miR-148A, miR-423, miR-92B, miR-611, miR-2110, and miR-548H4. To our knowledge this is the first report in which placental analysis has been used for determining the pathogenesis of and predicting VSD.

Siva-1 emerges as a tissue-specific oncogene beyond its classic role of a proapoptotic gene

Siva-1 is a typical apoptotic protein commonly activated by the p53 tumor suppressor protein and should therefore participate in a barrier against the development of cancer. It has proapoptotic activities in various cell systems. Recent findings suggest that Siva-1 possesses several other apoptosis-independent functions and interacts with many other proteins not directly involved in apoptosis. It harbors the ARF E3 ubiquitin protein ligase activity, a property that is clearly prooncogenic and leads to p53 degradation through the upregulation of the Hdm2 protein level. Surprisingly, recent evidence shows that Siva-1 absence prevents the development of non-small cell lung carcinomas in a mouse model and reveals the oncogenic roles in the same types of human cells, indicating its unique function as an oncogene in the cell context-dependent manner. Herein, we review reported activities of Siva-1 in various experimental settings and comment on its ambiguous function in tumor biology.

Identification of genes and genetic networks associated with BAG3‑dependent cell proliferation and cell survival in human cervical cancer HeLa cells

Bcl‑2‑associated athanogene (BAG) 3, is a member of the BAG protein family and a known co‑chaperone of heat shock protein (HSP) 70. BAG3 serves a role in regulating a variety of cellular functions, including cell growth, proliferation and cell death including apoptosis. BAG3 is a stress‑inducible protein, however the constitutive expression level of BAG3 is increased in cancer cells compared with healthy cells. Recent proteomics technology combined with bioinformatics has revealed that BAG3 participates in an interactome with a number of proteins other than its typical partner HSP70. The functional types represented in the interactome included nucleic acid binding proteins and transcription factors, as well as chaperones, which indicated that overexpression of BAG3 may contribute to proliferation and cell survival through the alteration of gene transcription. While an increasing number of studies have addressed the function of BAG3 as a co‑chaperone protein, BAG3‑dependent alteration of gene transcription has not been studied extensively. The present study established two BAG3 knockout human cervical cancer HeLa cell clones and addressed the role of BAG3 in cell proliferation and survival through gene transcription, using DNA microarray‑based transcriptome analysis and bioinformatics. The present study also identified two genetic networks associated with 'cellular growth and proliferation' and 'cell death and survival', which are dysregulated in the absence of BAG3, and may therefore be linked to BAG3 overexpression in cancer. These findings provide a molecular basis for understanding of BAG3‑dependent cell proliferation and survival from the aspect of alteration of gene expression.

N-n-Butyl Haloperidol Iodide, a Derivative of the Anti-psychotic Haloperidol, Antagonizes Hypoxia/Reoxygenation Injury by Inhibiting an Egr-1/ROS Positive Feedback Loop in H9c2 Cells

Early growth response-1 (Egr-1), a transcription factor which often underlies the molecular basis of myocardial ischemia/reperfusion (I/R) injury, and oxidative stress, is key to myocardial I/R injury. Silent information regulator of transcription 1(SIRT1) not only interacts with and is inhibited by Egr-1, but also downregulates reactive oxygen species (ROS) via the Forkhead box O1(FOXO1)/manganese superoxide dismutase (Mn-SOD) signaling pathway. N-n-butyl haloperidol iodide (F₂), a new patented compound, protects the myocardium against myocardial I/R injury in various animal I/R models in vivo and various heart-derived cell hypoxia/reoxygenation (H/R) models in vitro. In addition, F₂ can regulate the abnormal ROS/Egr-1 signaling pathway in cardiac microvascular endothelial cells (CMECs) and H9c2 cells after H/R. We studied whether there is an inverse Egr-1/ROS signaling pathway in H9c2 cells and whether the SIRT1/FOXO1/Mn-SOD signaling pathway mediates this. We verified a ROS/Egr-1 signaling loop in H9c2 cells during H/R and that F₂ protects against myocardial H/R injury by affecting SIRT1-related signaling pathways. Knockdown of Egr-1, by siRNA interference, reduced ROS generation, and alleviated oxidative stress injury induced by H/R, as shown by upregulated mitochondrial membrane potential, increased glutathione peroxidase (GSH-px) and total SOD anti-oxidative enzyme activity, and downregulated MDA. Decreases in FOXO1 protein expression and Mn-SOD activity occurred after H/R, but could be blocked by Egr-1 siRNA. F₂ treatment attenuated H/R-induced Egr-1 expression, ROS generation and other forms of oxidative stress injury such as MDA, and prevented H/R-induced decreases in FOXO1 and Mn-SOD activity_. Nuclear co-localization between Egr-1 and SIRT1 was increased by H/R and decreased by either Egr-1 siRNA or F₂. Therefore, our results suggest that Egr-1 inhibits the SIRT1/FOXO1/Mn-SOD antioxidant signaling pathway to increase ROS and perpetuate I/R injury. F₂ inhibits induction of Egr-1 by H/R, thereby activating SIRT1/FOXO1/Mn-SOD antioxidant signaling and decreasing H/R-induced ROS, demonstrating an important mechanism by which F₂ protects against myocardial H/R injury.

IL-22 Impedes the Proliferation of Schwann cells: Transcriptome Sequencing and Bioinformatics Analysis

Schwann cells (SCs) proliferation is crucial for nerve regeneration following nerve injury. This study aims to investigate effects of interleukin-22 (IL-22) on SCs proliferation in vitro, as well as the corresponding mechanism. Rat SCs were treated with 100 ng/ml rat IL-22 for 48 h, and cell proliferation and apoptosis were detected using fluorescent staining and flow cytometry. After transcriptome sequencing, raw reads were filtered and mapped to reference genome rn5. Then, differentially expressed genes (DEGs) and long non-coding RNAs (DElncRNAs) between IL-22 and control groups were identified (tool: Cuffdiff). Functional and pathway enrichment analyses were performed (tool: GOFunction), and protein-protein interaction (PPI) network was constructed (tool: STRING and Cytoscape). Furthermore, Pearson's correlations between DEGs and DElncRNAs were analyzed, and regulatory network of DEGs, DElncRNAs, and transcription factors (TFs) was constructed. IL-22 significantly inhibited proliferation (p value < 0.05) and promoted apoptosis of Schwann cells. Totally, 932 DEGs and 118 DElncRNAs were identified, among which Ccl2 and Ccna2 were hub genes in PPI network. Up-regulated DEGs were enriched in apoptosis related terms, whereas down-regulated DEGs were enriched in proliferation related terms. DElncRNAs like NONRATT023505, NONRATG020400, and NONRATT022748 were correlated with multiple DEGs enriched in cell cycle and division. Moreover, up-regulated TFs Egr1, Cebpd, and Atf4 play crucial roles in regulatory network, and NONRATG020400-Cebpd-Ccl2, NONRATT023505/NONRATT022748-Atf4-Ccna2, and NONRATT022748-Egr1-Id1/Aldoc/Eno2/F3/Serpine1 regulatory pathways were identified in SCs after IL-22 treatment. IL-22 might influence SCs proliferation and apoptosis via regulating lncRNA-TF-gene pathways in SCs. However, more studies are required to confirm these results.

Identification of cardioprotective agents from traditional Chinese medicine against oxidative damage

Reactive oxygen species are damaging to cardiomyocytes. H9c2 cardiomyocytes are commonly used to study the cellular mechanisms and signal transduction in cardiomyocytes, and to evaluate the cardioprotective effects of drugs following oxidative damage. The present study developed a robust, automated high throughput screening (HTS) assay to identify cardioprotective agents from a traditional Chinese medicine (TCM) library using a H₂O₂-induced oxidative damage model in H9c2 cells. Using this HTS format, several hits were identified as cardioprotective by detecting changes to cell viability using the cell counting kit (CCK)-8 assay. Two TCM extracts, KY-0520 and KY-0538, were further investigated. The results of the present study demonstrated that treatment of oxidatively damaged cells with KY-0520 or KY-0538 markedly increased the cell viability and superoxide dismutase activity, decreased lactate dehydrogenase activity and malondialdehyde levels, and inhibited early growth response-1 (Egr-1) protein expression. The present study also demonstrated that KY-0520 or KY-0538 treatment protected H9c2 cells from H₂O₂-induced apoptosis by altering the Bcl-2/Bax protein expression ratio, and decreasing the levels of cleaved caspase-3. In addition, KY-0520 and KY-0538 reduced the phosphorylation of ERK1/2 and p38-MAPK proteins, and inhibited the translocation of Egr-1 from the cytoplasm to nucleus in H₂O₂-treated H9c2 cells. These findings suggested that oxidatively damaged H9c2 cells can be used for the identification of cardioprotective agents that reduce oxidative stress by measuring cell viabilities using CCK-8 in an HTS format. The underlying mechanism of the cardioprotective activities of KY-0520 and KY-0538 may be attributed to their antioxidative activity, regulation of Egr-1 and apoptosis-associated proteins, and the inhibition of ERK1/2, p38-MAPK and Egr-1 signaling pathways.

Patterns of gene expression in the sheep heart during the perinatal period revealed by transcriptomic modeling

Septa from sheep hearts at 130 days gestation, term, and 14-day-old lambs were used to model the changes in gene expression patterns during the perinatal period using Agilent 15k ovine microarrays. We used Bioconductor for R to model five major patterns of coexpressed genes. Gene ontology and transcription factor analyses using Webgestalt modeled the biological significances and transcription factors of the gene expression patterns. Modeling indicated a decreased expression of genes associated with anatomical development and differentiation during this period, whereas those associated with increased protein synthesis and growth associated with maturation of the endoplasmic reticulum rose to term but did not further increase from the near term expression. Expression of genes associated with cell responsiveness, for example, immune responses, decreased at term but expression returned by postnatal day 14. Changes in genes related to metabolism showed differential substrate-associated patterns: those related to carbohydrate metabolism rose to term and remained stable thereafter, whereas those associated with fatty acid oxidation facility rose throughout the period. The timing of many of these maturational processes was earlier in relation to birth than in the rodent. The importance of the transcription factors, estrogen-related receptors, and v-myc avian myelocytomatosis viral oncogene homolog was also highlighted in the pattern of gene expression during development of the perinatal sheep heart.

Iron deficiency upregulates Egr1 expression

Iron-deficient anemia is a prevalent disease among humans. We searched for genes regulated by iron deficiency and its regulated mechanism. cDNA microarrays were performed using Hepa1c1c7 cells treated with 100 μM desferrioxamine (DFO), an iron chelator. Early growth response 1 (Egr1) was upregulated with at least 20-fold increase within 4 h and lasted for 24 h, which was confirmed by qRT-PCR. This activation was not seen by ferric ammonium citrate (FAC). DFO increased the transcriptional activity of Egr1-luc (-604 to +160) and serum response element (SRE)-luc reporters by 2.7-folds. In addition, cycloheximide lowered DFO-induced Egr1 mRNA levels. The upregulation of Egr1 by DFO was accompanied by sustained ERK signals along with phosphorylation of Elk-1. The ERK inhibitor (PD98059) prevented the DFO-induced Egr1 mRNAs. Overexpression of Elk-1 mutant (pElk-1S383A) decreased Egr1 reporter activity. DFO lowered reactive oxygen species (ROS) production and increased caspase 3/7 activity and cell death. DFO-induced iron deficiency upregulates Egr1 in part through transcriptional activation via ERK and Elk-1 signals, which may be important in the regulation of cell death in hepatoma cells. Our study demonstrated that iron depletion controlled the expression of Egr1, which might contribute to decisions about cellular fate in response to iron deficiency.