Isolation and characterization of a novel epithelium-specific transcription factor, ESE-1, a member of the ets family

The function of the ELF3 gene and its mechanism in cancers

E74-like factor 3 (ELF3) is an important member of the E-twenty-six (ETS) transcription factor family. ELF3 is expressed in various types of cells and regulates a variety of biological behaviors, such as cell proliferation, differentiation, apoptosis, migration, and invasion, by binding to DNA to regulate the expression of other genes. In recent years, studies have shown that ELF3 plays an important role in the occurrence and development of many tumors and inflammation and immune related diseases. ELF3 has different functions and expression patterns in different tumors; it can function as a tumor suppressor gene or an oncogene, highlighting its dual effects of tumor promotion and inhibition. ELF3 also affects the levels of tumor immunity-related cytokines and is involved in the regulation and expression of multiple signaling pathways. In tumor therapy, ELF3 is a complex and multifunctional gene and has become a key focus of targeted treatment research. An in-depth study of the biological function of ELF3 can help to elucidate its role in biological processes and provide ideas and a basis for the development and clinical application of ELF3-related therapeutic methods. This review introduces the structure and physiological and cellular functions of the ELF3 gene, summarizes the mechanisms of action of ELF3 in different types of malignant tumors and its role in immune regulation, inflammation, etc., and discusses treatment methods for ELF3-related diseases, providing significant reference value for scholars studying the ELF3 gene and related diseases.

Involvement of TLRs/NF-κB/ESE-1 signaling pathway in T-2 toxin-induced cartilage matrix degradation

T-2 toxin, a highly toxic type A monotrichothecene mycotoxin, has been found in many different types of cereals and is considered to be one of the most dangerous naturally occurring forms of food contamination. Globally, consuming grain-based food tainted with T-2 toxin poses significant risks to animal and human health. Prior research has indicated that the presence of T-2 toxin may lead to the demise of chondrocytes and the deterioration of the extracellular matrix of cartilage in degenerative bone and joint conditions, such as Kashin-Beck disease. However, the mechanisms by which T-2 toxin exerts its biological toxicity on the degradation of the extracellular matrix in cartilage are not well understood. In the current study, we found original results that demonstrate an upregulation of Toll-Like Receptors (TLR-2, TLR-4) and ESE-1 expression levels in the articular cartilage of a rat model subjected to T-2 toxin exposure. Furthermore, it was revealed that the exposure to T-2 toxin resulted in an increase in the expression of TLR-2, TLR-4, and ESE-1 in human C28/I2 chondrocytes. The findings of this study indicate that the increased expression of TLR-2, TLR-4, and ESE-1 may contribute to the development of degenerative osteoarthritic disease caused by T-2 toxin. Consistent with our hypotheses, we discovered that T-2 toxin increased the expression of MMP-1 and MMP-13 in human C28/I2 chondrocytes. We used a luciferase reporter gene assay to measure the activity of the ESE-1 promoter and transfected cells with plasmids encoding TLR-2 and TLR-4 to investigate their effects on this activity. TLR-2 and TLR-4 can activate ESE-1 transcriptional gene expression, and this expression is mediated through the NF-κB pathway, additional evidence is provided for the participation of the TLRs/NF-κB/ESE-1 signaling pathway in T-2 toxin-induced cartilage matrix degradation. Together, the findings indicated that the TLRs/NF-κB/ESE-1 signaling pathway played an essential part in T-2 toxin-induced cartilage matrix degradation.

The urothelial gene regulatory network: understanding biology to improve bladder cancer management

The urothelium is a stratified epithelium composed of basal cells, one or more layers of intermediate cells, and an upper layer of differentiated umbrella cells. Most bladder cancers (BLCA) are urothelial carcinomas. Loss of urothelial lineage fidelity results in altered differentiation, highlighted by the taxonomic classification into basal and luminal tumors. There is a need to better understand the urothelial transcriptional networks. To systematically identify transcription factors (TFs) relevant for urothelial identity, we defined highly expressed TFs in normal human bladder using RNA-Seq data and inferred their genomic binding using ATAC-Seq data. To focus on epithelial TFs, we analyzed RNA-Seq data from patient-derived organoids recapitulating features of basal/luminal tumors. We classified TFs as "luminal-enriched", "basal-enriched" or "common" according to expression in organoids. We validated our classification by differential gene expression analysis in Luminal Papillary vs. Basal/Squamous tumors. Genomic analyses revealed well-known TFs associated with luminal (e.g., PPARG, GATA3, FOXA1) and basal (e.g., TP63, TFAP2) phenotypes and novel candidates to play a role in urothelial differentiation or BLCA (e.g., MECOM, TBX3). We also identified TF families (e.g., KLFs, AP1, circadian clock, sex hormone receptors) for which there is suggestive evidence of their involvement in urothelial differentiation and/or BLCA. Genomic alterations in these TFs are associated with BLCA. We uncover a TF network involved in urothelial cell identity and BLCA. We identify novel candidate TFs involved in differentiation and cancer that provide opportunities for a better understanding of the underlying biology and therapeutic intervention.

ESE1/AGR2 axis antagonizes TGF-β-induced epithelial-mesenchymal transition in low-grade pancreatic cancer

Epithelium-specific ETS transcription factor 1 (ESE1) has been implicated in epithelial homeostasis, inflammation, as well as tumorigenesis, and cancer progression. However, numerous studies have reported contradictory roles-as an oncogene or a tumor suppressor of ESE1 in different cancers, and its function in the development and progression of pancreatic ductal adenocarcinoma (PDAC) has remained largely unexplored. Herein, we report that ESE1 was found upregulated in primary PDAC compared to normal pancreatic tissue, but high expression of ESE1 correlated to better relapse-free survival in patients with PDAC. Interestingly, ESE1 was found to exhibit dual roles in regulation of malignant properties of PDAC cells in that its overexpression promoted cell proliferation, whereas its downregulation enhanced epithelial-mesenchymal transition (EMT) phenotype. In the context of TGF-β-induced EMT, ESE1 is markedly downregulated at post-transcriptional level, and reconstituted ESE1 expression partially reversed TGF-β-induced EMT marker expression. Furthermore, we identify AGR2 as a novel transcriptional target of ESE1 that participates in TGF-β-induced EMT in PDAC. Collectively, our findings reveal an ESE1/AGR2 axis that interacts with TGF-β signaling to modulate EMT phenotype in PDAC.

IL-17A and TNF synergistically drive expression of proinflammatory mediators in synovial fibroblasts via IκBζ-dependent induction of ELF3

OBJECTIVE

IL-17A and TNF act in synergy to induce proinflammatory mediators in synovial fibroblasts thus contributing to diseases associated with chronic arthritis. Many of these factors are regulated by transcription factor E74-like factor-3 (ELF3). Therefore, we sought to investigate ELF3 as a downstream target of IL-17A and TNF signalling and to characterize its role in the molecular mechanism of synergy between IL-17A and TNF.

METHODS

Regulation of ELF3 expression by IL-17A and TNF was studied in synovial fibroblasts of RA and OA patients and RA synovial explants. Signalling leading to ELF3 mRNA induction and the impact of ELF3 on the response to IL-17A and TNF were studied using siRNA, transient overexpression and signalling inhibitors in synovial fibroblasts and HEK293 cells.

RESULTS

ELF3 was marginally affected by IL-17A or TNF alone, but their combination resulted in high and sustained expression. ELF3 expression was regulated by the nuclear factor-κB (NF-κB) pathway and CCAAT/enhancer-binding protein β (C/EBPβ), but its induction required synthesis of the NF-κB co-factor IκB (inhibitor of NF-κB) ζ. siRNA-mediated depletion of ELF3 attenuated the induction of cytokines and matrix metalloproteinases by the combination of IL-17A and TNF. Overexpression of ELF3 or IκBζ showed synergistic effect with TNF in upregulating expression of chemokine (C-C motif) ligand 8 (CCL8), and depletion of ELF3 abrogated CCL8 mRNA induction by the combination of IκBζ overexpression and TNF.

CONCLUSION

Altogether, our results establish ELF3 as an important mediator of the synergistic effect of IL-17A and TNF in synovial fibroblasts. The findings provide novel information of the pathogenic mechanisms of IL-17A in chronic arthritis and implicate ELF3 as a potential therapeutic target.

MYB and ELF3 differentially modulate labor-inducing gene expression in myometrial cells

Spontaneous uterine contractions are initiated when smooth muscle cells (SMCs) within the uterine muscle, or myometrium, transition from a functionally dormant to an actively contractile phenotype at the end of the pregnancy period. We know that this process is accompanied by gestational time point-specific differences in the SMC transcriptome, which can be modulated by the activator protein 1 (AP-1), nuclear factor kappa beta (NF-κβ), estrogen receptor (ER), and progesterone receptor (PR) transcription factors. Less is known, however, about the additional proteins that might assist these factors in conferring the transcriptional changes observed at labor onset. Here, we present functional evidence for the roles of two proteins previously understudied in the SMC context-MYB and ELF3-which can contribute to the regulation of labor-driving gene transcription. We show that the MYB and ELF3 genes exhibit elevated transcript expression levels in mouse and human myometrial tissues during spontaneous term labor. The expression of both genes was also significantly increased in mouse myometrium during preterm labor induced by the progesterone antagonist mifepristone (RU486), but not during infection-simulating preterm labor induced by intrauterine infusion of lipopolysaccharide (LPS). Furthermore, both MYB and ELF3 proteins affect labor-driving gene promoter activity, although in surprisingly opposing ways: Gja1 and Fos promoter activation increases in the presence of MYB and decreases in the presence of ELF3. Collectively, our study adds to the current understanding of the transcription factor network that defines the transcriptomes of SMCs during late gestation and implicates two new players in the control of labor timing.

Elf3 deficiency during zebrafish development alters extracellular matrix organization and disrupts tissue morphogenesis

E26 transformation specific (ETS) family transcription factors are expressed during embryogenesis and are involved in various cellular processes such as proliferation, migration, differentiation, angiogenesis, apoptosis, and survival of cellular lineages to ensure appropriate development. Dysregulated expression of many of the ETS family members is detected in different cancers. The human ELF3, a member of the ETS family of transcription factors, plays a role in the induction and progression of human cancers is well studied. However, little is known about the role of ELF3 in early development. Here, the zebrafish elf3 was cloned, and its expression was analyzed during zebrafish development. Zebrafish elf3 is maternally deposited. At different developmental stages, elf3 expression was detected in different tissue, mainly neural tissues, endoderm-derived tissues, cartilage, heart, pronephric duct, blood vessels, and notochord. The expression levels were high at the tissue boundaries. Elf3 loss-of-function consequences were examined by using translation blocking antisense morpholino oligonucleotides, and effects were validated using CRISPR/Cas9 knockdown. Elf3-knockdown produced short and bent larvae with notochord, craniofacial cartilage, and fin defects. The extracellular matrix (ECM) in the fin and notochord was disorganized. Neural defects were also observed. Optic nerve fasciculation (bundling) and arborization in the optic tectum were defective in Elf3-morphants, and fragmentation of spinal motor neurons were evident. Dysregulation of genes encoding ECM proteins and matrix metalloprotease (MMP) and disorganization of ECM may play a role in the observed defects in Elf3 morphants. We conclude that zebrafish Elf3 is required for epidermal, mesenchymal, and neural tissue development.

ETS transcription factor ELF3 (ESE-1) is a cell cycle regulator in benign and malignant prostate

This study aimed to elucidate the role of ELF3, an ETS family member in normal prostate growth and prostate cancer. Silencing ELF3 in both benign prostate (BPH-1) and prostate cancer (PC3) cell lines resulted in decreased colony forming ability, inhibition of cell migration and reduced cell viability due to cell cycle arrest, establishing ELF3 as a cell cycle regulator. Increased ELF3 expression in more advanced prostate tumours was shown by immunostaining of tissue microarrays and from analysis of gene expression and genetic alteration studies. This study indicates that ELF3 functions as part of normal prostate epithelial growth but also as a potential oncogene in advanced prostate cancers.

Propofol protects against high glucose-mediated endothelial injury via inhibition of COX2 and iNOS expressions

Perioperative hyperglycemia is a common metabolic disorder in the clinic. Hyperglycemia, via upregulation of E74-like ETS transcription factor 3 (ELF3), induces cyclooxygenase 2 (COX2) and inducible nitric oxide synthase (iNOS) expressions, thus leading to endothelial apoptosis and vascular endothelial injury. Propofol is a widely used anesthetic. In the present study, we explored whether and how propofol protects against high glucose-induced COX2 and iNOS expressions in human umbilical vein endothelial cells (HUVECs). We found that high glucose level decreases cell viability and increases COX2 and iNOS expressions in HUVECs. Our data also indicated that ELF3 overexpression participates in high glucose-mediated cell viability reduction and high glucose-induced COX2 and iNOS expressions. Moreover, propofol treatment improves high glucose-mediated reduction in cell viability and decreases COX2 and iNOS expressions via inhibition of ELF3 expressions. Furthermore, specificity protein 1 (SP1) was found to regulate ELF3 expression, thus mediating endothelial injury. Propofol inhibits high glucose-induced SP1 expression. High glucose increases the abundance of SP1 bound to the ELF3 promoter, which can be reversed by propofol treatment. The protective effect of propofol is reversed by SP1 overexpression. In conclusion, propofol downregulates high glucose-induced SP1 expression, thus attenuating high glucose-induced ELF3 expression, inhibiting high glucose-induced COX2 and iNOS expressions, and improving high glucose-mediated cell viability reduction in HUVECs.

A Versatile Human Intestinal Organoid-Derived Epithelial Monolayer Model for the Study of Enteric Pathogens

Gastrointestinal infections cause significant morbidity and mortality worldwide. The complexity of human biology and limited insights into host-specific infection mechanisms are key barriers to current therapeutic development. Here, we demonstrate that two-dimensional epithelial monolayers derived from human intestinal organoids, combined with in vivo-like bacterial culturing conditions, provide significant advancements for the study of enteropathogens. Monolayers from the terminal ileum, cecum, and ascending colon recapitulated the composition of the gastrointestinal epithelium, in which several techniques were used to detect the presence of enterocytes, mucus-producing goblet cells, and other cell types following differentiation. Importantly, the addition of receptor activator of nuclear factor kappa-B ligand (RANKL) increased the presence of M cells, critical antigen-sampling cells often exploited by enteric pathogens. For infections, bacteria were grown under in vivo-like conditions known to induce virulence. Overall, interesting patterns of tissue tropism and clinical manifestations were observed. Shigella flexneri adhered efficiently to the cecum and colon; however, invasion in the colon was best following RANKL treatment. Both Salmonella enterica serovars Typhi and Typhimurium displayed different infection patterns, with S. Typhimurium causing more destruction of the terminal ileum and S. Typhi infecting the cecum more efficiently than the ileum, particularly with regard to adherence. Finally, various pathovars of Escherichia coli validated the model by confirming only adherence was observed with these strains. This work demonstrates that the combination of human-derived tissue with targeted bacterial growth conditions enables powerful analyses of human-specific infections that could lead to important insights into pathogenesis and accelerate future vaccine development. IMPORTANCE While traditional laboratory techniques and animal models have provided valuable knowledge in discerning virulence mechanisms of enteric pathogens, the complexity of the human gastrointestinal tract has hindered our understanding of physiologically relevant, human-specific interactions; and thus, has significantly delayed successful vaccine development. The human intestinal organoid-derived epithelial monolayer (HIODEM) model closely recapitulates the diverse cell populations of the intestine, allowing for the study of human-specific infections. Differentiation conditions permit the expansion of various cell populations, including M cells that are vital to immune recognition and the establishment of infection by some bacteria. We provide details of reproducible culture methods and infection conditions for the analyses of Shigella, Salmonella, and pathogenic Escherichia coli in which tissue tropism and pathogen-specific infection patterns were detected. This system will be vital for future studies that explore infection conditions, health status, or epigenetic differences and will serve as a novel screening platform for therapeutic development.

Vorinostat ameliorates IL-1α-induced reduction of type II collagen by inhibiting the expression of ELF3 in chondrocytes

Osteoarthritis (OA) is a common joint disease that ultimately causes physical disability and imposes an economic burden on society. Cartilage destruction plays a key role in the development of OA. Vorinostat is an oral histone deacetylase (HDAC) inhibitor and has been used for the treatment of T-cell lymphoma. Previous studies have reported the anti-inflammatory effect of HDAC inhibitors in both in vivo and in vitro models. However, it is unknown whether vorinostat exerts a protective effect in OA. In this study, our results demonstrate that treatment with vorinostat prevents interleukin 1α (IL-1α)-induced reduction of type II collagen at both gene and protein levels. Treatment with vorinostat reduced the IL-1α-induced production of mitochondrial reactive oxygen species (ROS) in T/C-28a2 cells. Additionally, vorinostat rescued the IL-1α-induced decrease in the expression of the collagen type II a1 (Col2a1) gene and the expression of Sry-related HMG box 9 (SOX-9). Importantly, we found that vorinostat inhibited the expression of matrix metalloproteinase-13 (MMP-13), which is responsible for the degradation of type II collagen. Furthermore, vorinostat suppressed the expression of E74-like factor 3 (ELF3), which is a key transcription factor that plays a pivotal role in the IL-1α-induced reduction of type II collagen. Also, the overexpression of ELF3 abolished the protective effects of vorinostat against IL-1α-induced loss of type 2 collagen by inhibiting the expression of SOX-9 whilst increasing the expression of MMP-13. In conclusion, our findings suggest that vorinostat might prevent cartilage destruction by rescuing the reduction of type II collagen, mediated by the suppression of ELF3.

ELF3 activated by a superenhancer and an autoregulatory feedback loop is required for high-level HLA-C expression on extravillous trophoblasts

HLA-C arose during evolution of pregnancy in the great apes 10 to 15 million years ago. It has a dual function on placental extravillous trophoblasts (EVTs) as it contributes to both tolerance and immunity at the maternal-fetal interface. The mode of its regulation is of considerable interest in connection with the biology of pregnancy and pregnancy abnormalities. First-trimester primary EVTs in which HLA-C is highly expressed, as well as JEG3, an EVT model cell line, were employed. Single-cell RNA-seq data and quantitative PCR identified high expression of the transcription factor ELF3 in those cells. Chromatin immunoprecipitation (ChIP)-PCR confirmed that both ELF3 and MED1 bound to the proximal HLA-C promoter region. However, binding of RFX5 to this region was absent or severely reduced, and the adjacent HLA-B locus remained closed. Expression of HLA-C was inhibited by ELF3 small interfering RNAs (siRNAs) and by wrenchnolol treatment. Wrenchnolol is a cell-permeable synthetic organic molecule that mimics ELF3 and is relatively specific for binding to ELF3's coactivator, MED23, as our data also showed in JEG3. Moreover, the ELF3 gene is regulated by a superenhancer that spans more than 5 Mb, identified by assay for transposase-accessible chromatin using sequencing (ATAC-seq), as well as by its sensitivity to (+)-JQ1 (inhibitor of BRD4). ELF3 bound to its own promoter, thus creating an autoregulatory feedback loop that establishes expression of ELF3 and HLA-C in trophoblasts. Wrenchnolol blocked binding of MED23 to ELF3, thus disrupting the positive-feedback loop that drives ELF3 expression, with down-regulation of HLA-C expression as a consequence.

Nanopore Sequencing Unveils Diverse Transcript Variants of the Epithelial Cell-Specific Transcription Factor Elf-3 in Human Malignancies

The human E74-like ETS transcription factor 3 (Elf-3) is an epithelium-specific member of the ETS family, all members of which are characterized by a highly conserved DNA-binding domain. Elf-3 plays a crucial role in epithelial cell differentiation by participating in morphogenesis and terminal differentiation of the murine small intestinal epithelium, and also acts as an indispensable regulator of mesenchymal to epithelial transition, underlying its significant involvement in development and in pathological states, such as cancer. Although previous research works have deciphered the functional role of Elf-3 in normal physiology as well as in tumorigenesis, the present study highlights for the first time the wide spectrum of ELF3 mRNAs that are transcribed, providing an in-depth analysis of splicing events and exon/intron boundaries in a broad panel of human cell lines. The implementation of a versatile targeted nanopore sequencing approach led to the identification of 25 novel ELF3 mRNA transcript variants (ELF3 v.3–v.27) with new alternative splicing events, as well as two novel exons. Although the current study provides a qualitative transcriptional profile regarding ELF3, further studies must be conducted, so the biological function of all novel alternative transcript variants as well as the putative protein isoforms are elucidated.

Epithelium-specific ETS transcription factor-1 regulates NANOG expression and inhibits NANOG-induced proliferation of human embryonic carcinoma cells

The epithelium-specific ETS transcription factor-1 (ESE-1) plays multiple roles in pathogenesis and normal development of epithelial tissues. NANOG, a key mediator of stem cell self-renewal and pluripotency, is also expressed in various cancers and pluripotent cells. In this study, we investigated how ESE-1 influences NANOG expression and NANOG-induced proliferation in human germ cell-derived embryonic carcinoma NCCIT cells. Endogenous ESE-1 expression in NCCIT cells significantly increased during differentiation, whereas NANOG expression decreased. In addition, NANOG expression was downregulated by exogenous overexpression of ESE-1, and increased by shRNA-mediated knockdown of ESE-1. NANOG transcriptional activity was reduced by dose-dependent ESE-1 overexpression and a putative ESE-1 binding site (EBS) was mapped within conserved region 2. Site-directed mutagenesis of the putative EBS abrogated the repressive effect of ESE-1 on NANOG promoter activity. ESE-1 directly interacted with the putative EBS to regulate transcriptional activity of NANOG. Furthermore, NANOG-induced proliferation and colony formation of NCCIT cells were inhibited by ESE-1 overexpression and stimulated by ESE-1 shRNA-mediated knockdown. Altogether, our results suggest that ESE-1 exerts an anti-proliferative effect on NCCIT cells by acting as a novel transcriptional repressor of NANOG.

Transcriptional and signalling regulation of skin epithelial stem cells in homeostasis, wounds and cancer

The epidermis and skin appendages are maintained by their resident epithelial stem cells, which undergo long-term self-renewal and multilineage differentiation. Upon injury, stem cells are activated to mediate re-epithelialization and restore tissue function. During this process, they often mount lineage plasticity and expand their fates in response to damage signals. Stem cell function is tightly controlled by transcription machineries and signalling transductions, many of which derail in degenerative, inflammatory and malignant dermatologic diseases. Here, by describing both well-characterized and newly emerged pathways, we discuss the transcriptional and signalling mechanisms governing skin epithelial homeostasis, wound repair and squamous cancer. Throughout, we highlight common themes underscoring epithelial stem cell plasticity and tissue-level crosstalk in the context of skin physiology and pathology.

High glucose mediates NLRP3 inflammasome activation via upregulation of ELF3 expression

Microtubule affinity regulating kinase 4 (MARK4) plays a crucial role in the regulation of NOD-like receptor pyrin domain 3 (NLRP3) inflammasome activation, which leads to the generation of bioactive interleukin (IL)-1β and IL-18. E74-like ETS transcription factor 3 (ELF3) participates in endothelial inflammatory processes. We hypothesized that ELF3 modulates MARK4 expression in vascular endothelial cells, thus contributing to high glucose-mediated NLRP3 inflammasome activation. Plasma IL-1β, IL-18, NLRP3 inflammasome and MARK4 expression was increased in diabetic patients and rats. An in vitro study indicated that high glucose increased IL-1β and IL-18 expression and activated the NLRP3 inflammasome via upregulation of MARK4 in human umbilical vein endothelial cells (HUVECs). Furthermore, high glucose increased ELF3 expression. ELF3 downregulation reversed the effects of high glucose treatment. Accordingly, the effects of ELF3 overexpression were similar to those of high glucose treatment and were counteracted by siMARK4. Furthermore, ELF3 was found to interact with SET8. High glucose inhibited SET8 expression and histone H4 lysine 20 methylation (H4K20me1), a downstream target of SET8. Overexpression of SET8 inhibited high glucose-induced MARK4 expression and NLRP3 inflammasome activation. The effects of shSET8 were similar to those of high glucose treatment and were counteracted by siMARK4. A mechanistic study found that ELF3 and H4K20me1 were enriched in the MARK4 promoter region. si-ELF3 attenuated MARK4 promoter activity and augmented the inhibitory effect of SET8 on MARK4 promoter activity. Furthermore, SET8 downregulation and ELF3 upregulation were confirmed in diabetic patients and rats. In conclusion, ELF3 interacted with SET8 to modulate MARK4 expression, which participated in hyperglycaemia-mediated endothelial NLRP3 inflammasome activation.

Circular RNAs in nasopharyngeal carcinoma

BACKGROUND

Nasopharyngeal carcinoma (NPC) is a geographical distributed epithelial tumor of head and neck, which is prevalent in east Africa and Asia, especially southern China. Moreover, NPC has an unfavorable clinical effect and is prone to metastasis at an advanced stage. Although the recovery rate of patients has been improved due to concurrent chemoradiotherapy, poor curative effects and low overall survival remain key issues. The precise mechanisms and pivotal regulators of NPC remain still unclear. To improve the therapeutic efficacy, we focused on related-NPC circular RNAs (circRNAs). CircRNAs are a unique type of endogenous non-coding RNAs (ncRNAs) with a covalent closed-loop structure. Their expression is rich, stable and conservative. Different circRNA have specific tissue and developmental stages and can be detected in body fluids. In addition, circRNAs are involved in multiple pathological processes, especially in cancers. In recent years, using high-throughput indicator technology and bioinformatics technology, a large number of circRNAs have been identified in NPC cells and verified to have biological functions and mechanisms of action. This article aims to provide a retrospective review of the latest research on the proliferation and migration of related-NPC circRNA. Specifically, we focused on the roles and mechanisms of circRNAs in the development and progression of NPC.

CONCLUSION

CircRNA can act as an oncogene or tumor suppressor gene and participate in NPC progression (e.g., proliferation, apoptosis, migration, and invasion). In short, circRNAs have potential as biomarkers for the diagnosis, prognosis and treatment of NPC.

miR-320/ELF3 axis inhibits the progression of breast cancer via the PI3K/AKT pathway

There is increasing evidence demonstrating that disorders affecting microRNAs (miRs) influence tumorigenesis and progression, which results in a poor prognosis in patients with breast cancer (BC). In the present study, the precise molecular mechanism underlying the role of miR-320 in the progression of BC was investigated. Reverse transcription-quantitative PCR was conducted to determine mRNA expression, and western blot analysis was used to test protein levels. An MTT assay was conducted to detect cell viability and Transwell assays were used to analyze cell migration and invasion abilities. Furthermore, E74-like factor 3 (ELF3) protein density was tested via immunohistochemistry. Tumor volume was detected by xenograft tumor formation assay. The current results indicated that miR-320 expression was downregulated in BC tissues and cells, and was associated with a poor prognosis of patients with BC. Overexpression of miR-320 inhibited cell proliferation, migration and invasion via inhibition of the epithelial-mesenchymal transition and the PI3K/AKT signaling pathway in BC cells. Furthermore, it was revealed that the tumor size and weight were smaller in nude mice that had been transfected to overexpress miR-320. The luciferase reporter assay demonstrated the direct binding of miR-320 to the 3′ untranslated region of ELF3 mRNA, which may further downregulate ELF3. Overall, the present results provided evidence that miR-320 may be a tumor suppressor in BC, and that the miR-320/ELF3 axis regulated tumor progression via the PI3K/AKT signaling pathway, which may represent a novel treatment strategy for BC.

Deducing signaling pathways from parallel actions of arsenite and antimonite in human epidermal keratinocytes

Inorganic arsenic oxides have been identified as carcinogens in several human tissues, including epidermis. Due to the chemical similarity between trivalent inorganic arsenic (arsenite) and antimony (antimonite), we hypothesized that common intracellular targets lead to similarities in cellular responses. Indeed, transcriptional and proteomic profiling revealed remarkable similarities in differentially expressed genes and proteins resulting from exposure of cultured human epidermal keratinocytes to arsenite and antimonite in contrast to comparisons of arsenite with other metal compounds. These data were analyzed to predict upstream regulators and affected signaling pathways following arsenite and antimonite treatments. A majority of the top findings in each category were identical after treatment with either compound. Inspection of the predicted upstream regulators led to previously unsuspected roles for oncostatin M, corticosteroids and ephrins in mediating cellular response. The influence of these predicted mediators was then experimentally verified. Together with predictions of transcription factor effects more generally, the analysis has led to model signaling networks largely accounting for arsenite and antimonite action. The striking parallels between responses to arsenite and antimonite indicate the skin carcinogenic risk of exposure to antimonite merits close scrutiny.

High Glucose Induces Endothelial COX2 and iNOS Expression via Inhibition of Monomethyltransferase SETD8 Expression

Cyclooxygenase 2 (COX2) and inducible nitric oxide synthase (iNOS) overexpression results in endothelial apoptosis, thus mediating vascular endothelial injury in hyperglycaemia. E26 transformation-specific sequence transcription factor-1 (ESE-1), which belongs to the E26 transformation-specific family of transcription factors, has been demonstrated to be involved in COX2 and iNOS gene transcription. Our previous study indicated that SET domain-containing protein 8 (SETD8) downregulation is involved in high glucose-mediated endothelial inflammation in human umbilical vein endothelial cells (HUVECs). Here, we report that SETD8 plays a major role in hyperglycaemia-induced COX2 and iNOS expression. In HUVECs, upregulation of ESE-1 expression was related to high glucose-mediated apoptosis and COX2 and iNOS expression. High glucose inhibited SETD8 expression, and overexpression of SETD8 diminished the effects of high glucose treatment. Consistently, RNA silencing of SETD8 led to the opposite effect. Furthermore, SETD8 was found to interact with specificity protein 1 (SP1). Blockade of SP1 protected against high glucose-mediated endothelial injury. Mechanistically, we showed that H4K20me1, a downstream target of SETD8, and SP1 were enriched at the ESE-1 promoter region by ChIP assay. Luciferase reporter assays indicated that SETD8 overexpression attenuated ESE-1 promoter activity and augmented the inhibitory effect of siSP1 on ESE-1 promoter activity. In general, our data indicate that SETD8 interacts with SP1 to coregulate ESE-1 expression, which is involved in hyperglycaemia-mediated endothelial apoptosis in HUVECs.

Epithelial tumor suppressor ELF3 is a lineage-specific amplified oncogene in lung adenocarcinoma

Gene function in cancer is often cell type-specific. The epithelial cell-specific transcription factor ELF3 is a documented tumor suppressor in many epithelial tumors yet displays oncogenic properties in others. Here, we show that ELF3 is an oncogene in the adenocarcinoma subtype of lung cancer (LUAD), providing genetic, functional, and clinical evidence of subtype specificity. We discover a region of focal amplification at chromosome 1q32.1 encompassing the ELF3 locus in LUAD which is absent in the squamous subtype. Gene dosage and promoter hypomethylation affect the locus in up to 80% of LUAD analyzed. ELF3 expression was required for tumor growth and a pan-cancer expression network analysis supports its subtype and tissue specificity. We further show that ELF3 displays strong prognostic value in LUAD but not LUSC. We conclude that, contrary to many other tumors of epithelial origin, ELF3 is an oncogene and putative therapeutic target in LUAD.

Tissue context can dictate why a gene can have seemingly opposing functions in different settings. ELF3 is tumor suppressive in many cancers of epithelial origin but in lung cancer, the authors describe an oncogenic role in the adenocarcinoma histology of non-small cell lung cancer.

Single Nucleotide Polymorphisms of NUCB2 and their Genetic Associations with Milk Production Traits in Dairy Cows

We previously used the RNA sequencing technique to detect the hepatic transcriptome of Chinese Holstein cows among the dry period, early lactation, and peak of lactation, and implied that the nucleobindin 2 (NUCB2) gene might be associated with milk production traits due to its expression being significantly increased in early lactation or peak of lactation as compared to dry period (q value < 0.05). Hence, in this study, we detected the single nucleotide polymorphisms (SNPs) of NUCB2 and analyzed their genetic associations with milk yield, fat yield, fat percentage, protein yield, and protein percentage. We re-sequenced the entire coding and 2000 bp of 5′ and 3′ flanking regions of NUCB2 by pooled sequencing, and identified ten SNPs, including one in 5′ flanking region, two in 3′ untranslated region (UTR), and seven in 3′ flanking region. The single-SNP association analysis results showed that the ten SNPs were significantly associated with milk yield, fat yield, fat percentage, protein yield, or protein percentage in the first or second lactation (p values <= 1 × 10⁻⁴ and 0.05). In addition, we estimated the linkage disequilibrium (LD) of the ten SNPs by Haploview 4.2, and found that the SNPs were highly linked in one haplotype block (D′ = 0.98–1.00), and the block was also significantly associated with at least one milk traits in the two lactations (p values: 0.0002–0.047). Further, we predicted the changes of transcription factor binding sites (TFBSs) that are caused by the SNPs in the 5′ flanking region of NUCB2, and considered that g.35735477C>T might affect the expression of NUCB2 by changing the TFBSs for ETS transcription factor 3 (ELF3), caudal type homeobox 2 (CDX2), mammalian C-type LTR TATA box (VTATA), nuclear factor of activated T-cells (NFAT), and v-ets erythroblastosis virus E26 oncogene homolog (ERG) (matrix similarity threshold, MST > 0.85). However, the further study should be performed to verify the regulatory mechanisms of NUCB2 and its polymorphisms on milk traits. Our findings first revealed the genetic effects of NUCB2 on the milk traits in dairy cows, and suggested that the significant SNPs could be used in genomic selection to improve the accuracy of selection for dairy cattle breeding.

ESE1 expression correlates with neuronal apoptosis in the hippocampus after cerebral ischemia/reperfusion injury

Epithelial-specific ETS-1 (ESE1), a member of the ETS transcription factor family, is widely expressed in multiple tissues and performs various functions in inflammation. During neuroinflammation, ESE1 promotes neuronal apoptosis; however, the expression and biological functions of ESE1 remain unclear after cerebral ischemia/reperfusion. We performed in vivo and in vitro experiments to explore the role of ESE1 in cerebral ischemic injury. A modified four vessel occlusion method was used in adult Sprague-Dawley rats. At 6, 12, 24, 48, and 72 hours after model induction, the hippocampus was collected for analysis. Western blot assays and immunohistochemistry showed that the expression of ESE1, phosphorylated p65 and active caspase-3 was significantly up-regulated after ischemia. Double immunofluorescence staining indicated that ESE1 and NeuN were mostly co-located in the hippocampus after ischemia. Furthermore, ESE1 was also co-expressed with active caspase-3. PC12 cells were stimulated with cobalt chloride (CoCl₂) to establish a chemical hypoxia model. After ESE1 knockdown by siRNA for 6 hours, cell viability was detected by 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide assays. The levels of ESE1, phosphorylated p65 and active caspase-3 were also remarkably increased in PC12 cells after CoCl₂ stimulation. After ESE1 knockdown, PC12 cell viability was increased after hypoxia. siRNA knockdown of ESE1 decreased the level of p-p65 and active caspase-3 after CoCl₂ stimulation. These data reveal that ESE1 levels are elevated in the hippocampus after cerebral ischemia/reperfusion injury. This may play a role in neuronal apoptosis via activation of the nuclear factor-κB pathway.

ELF3, ELF5, EHF and SPDEF Transcription Factors in Tissue Homeostasis and Cancer

The epithelium-specific ETS (ESE) transcription factors (ELF3, ELF5, EHF and SPDEF) are defined by their highly conserved ETS DNA binding domain and predominant epithelial-specific expression profile. ESE transcription factors maintain normal cell homeostasis and differentiation of a number of epithelial tissues, and their genetic alteration and deregulated expression has been linked to the progression of several epithelial cancers. Herein we review the normal function of the ESE transcription factors, the mechanisms by which they are dysregulated in cancers, and the current evidence for their role in cancer progression. Finally, we discuss potential therapeutic strategies for targeting or reactivating these factors as a novel means of cancer treatment.

MiR-320a-3p/ELF3 axis regulates cell metastasis and invasion in non-small cell lung cancer via PI3K/Akt pathway

MicroRNAs (miRNAs) play important roles in tumorigenesis and tumor progression. In this study, we investigated the role of miR-320a-3p in non-small cell lung cancer (NSCLC). Expressions of miR-320a-3p were firstly determined in 80 NSCLC patients' cancer tissues and adjacent normal lung tissues by qRT-PCR. Then MTT assay, cell migration and invasion assays were performed in vitro. Potential binding sites on target gene of miR-320a-3p were predicted and luciferase reporter assay was used to identify the potential binding sites. Tumorigenesis assay were performed in nude mice by injecting A549 cells which stably express miR-320a-3p. Results indicated that high expression of miR-320a-3p suppresses cell proliferation, migration and invasion through the inactivation of PI3K/Akt signaling pathway in NSCLC cells. Smaller tumor size and lighter weight were also found in nude mice which had miR-320a-3p higher expressed. Furthermore, data from luciferase reporter assay proved the direct binding of miR-320a-3p on the 3'UTR region of ELF3 mRNA, this could further decrease ELF3 expression transcriptionally. We provided evidence that miR-320a-3p might work as a tumor suppressor in NSCLC both in vivo and in vitro.

ELF3 promotes epithelial-mesenchymal transition by protecting ZEB1 from miR-141-3p-mediated silencing in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is one of the most common malignant cancers and currently the third leading cause of cancer-related deaths, worldwide. Epithelial-mesenchymal transition (EMT) plays a major role in HCC progression. In this study, we first found that the expression of E74-like ETS transcription factor 3 (ELF3), a member of the E-twenty-six family of transcription factors, was increased in HCC tissues, and that ELF3 overexpression was associated with poor prognoses for HCC patients. Gain-of-function and loss-of-function studies revealed that increased ELF3 expression promoted HCC cell proliferation, migration, and invasion, while these processes were inhibited when ELF3 was silenced. Additionally, ELF3 was found to promote EMT, which we demonstrated through decreased E-cadherin expression and increased N-cadherin and fibronectin expression. ELF3 knockdown reversed EMT via repressing ZEB1 expression through miR-141-3p upregulation. Chromatin immunoprecipitation assays revealed that ELF3 bound to the miR-141-3p promoter, suppressing miR-141-3p expression. Taken together, our data show that ELF3 repressed E-cadherin and promoted EMT in HCC cells by suppressing miR-141-3p, thereby activating ZEB1. Thus, ELF3 may be a potential prognostic biomarker and/or therapeutic target for HCC.

Overexpression of ELF3 facilitates cell growth and metastasis through PI3K/Akt and ERK signaling pathways in non-small cell lung cancer

ELF3 is one of the member of transcription factors from E-twenty-six family, its role varies in different types of cancer. However, the role and specific mechanisms of ELF3 in the development of non-small cell lung cancer (NSCLC) still remains largely unknown. In our study, ELF3 was observed to be upregulated in NSCLC tissues compared to the corresponding normal lung tissue at mRNA and protein levels, and its expression level was correlated with the overall survival of patients with NSCLC. Silencing of the ELF3 gene in NSCLC cells inhibited the proliferation and metastasis significantly in vitro and in vivo. Conversely, overexpression of ELF3 in NSCLC cells promoted cancer growth and metastasis in vitro. Mechanistically, ELF3 activated PI3K/AKT and ERK signaling pathways and its downstream effectors, thus regulating the cell cycle and epithelial-mesenchymal transition (EMT). Furthermore, the promotive effects of ELF3 on cellular proliferation and metastasis could be rescued by Ly294002 (inhibitor of PI3K) and U0126 (inhibitor of MEK1/2). The results show that ELF3 promotes cell growth and metastasis by regulating PI3K/Akt and ERK pathways in NSCLC and that it may be a promising new target for the treatment of NSCLC patients.

ESE-1/ELF3 mRNA expression associates with poor survival outcomes in HER2+ breast cancer patients and is critical for tumorigenesis in HER2+ breast cancer cells

ESE-1/Elf3 and HER2 appear to establish a positive feedback regulatory loop, but the precise role of ESE-1 in HER2⁺ breast tumorigenesis remains unknown. Analyzing public repositories, we found that luminal B and HER2 subtype patients with high ESE-1 mRNA levels displayed worse relapse free survival. We stably knocked down ESE-1 in HER2⁺ luminal B BT474 cells and HER2 subtype SKBR3 cells, which resulted in decreased cell proliferation, colony formation, and anchorage-independent growth in vitro. Stable ESE-1 knockdown inhibited HER2-dependent signaling in BT474 cells and inhibited mTOR activation in SKBR3 cells, but reduced Akt signaling in both cell types. Expression of a constitutively-active Myr-Akt partially rescued the anti-proliferative effect of ESE-1 knockdown in both cell lines. Furthermore, ESE-1 knockdown inhibited cyclin D1, resulting in a G1 delay in both cell lines. Finally, ESE-1 knockdown completely inhibited BT474 cell xenograft tumors in NOD/SCID female mice, which correlated with reduced in vitro tumorsphere formation. Taken together, these results reveal the ESE-1 controls transformation via distinct upstream signaling mechanisms in SKBR3 and BT474 cells, which ultimately impinge on Akt and cyclin D1 in both cell types to regulate cell proliferation. Particularly significant is that ESE-1 controls tumorigenesis and is associated with worse clinical outcomes in HER2 breast cancer.

Stem cells and the role of ETS transcription factors in the differentiation hierarchy of normal and malignant prostate epithelium

Prostate cancer is the most common cancer of men in the UK and accounts for a quarter of all new cases. Although treatment of localised cancer can be successful, there is no cure for patients presenting with invasive prostate cancer and there are less treatment options. They are generally treated with androgen-ablation therapies but eventually the tumours become hormone resistant and patients develop castration-resistant prostate cancer (CRPC) for which there are no further successful or curative treatments. This highlights the need for new treatment strategies. In order to prevent prostate cancer recurrence and treatment resistance, all the cell populations in a heterogeneous prostate tumour must be targeted, including the rare cancer stem cell (CSC) population. The ETS transcription factor family members are now recognised as a common feature in multiple cancers including prostate cancer; with aberrant expression, loss of tumour suppressor function, inactivating mutations and the formation of fusion genes observed. Most notably, the TMPRSS2-ERG gene fusion is present in approximately 50% of prostate cancers and in prostate CSCs. However, the role of other ETS transcription factors in prostate cancer is less well understood. This review will describe the prostate epithelial cell hierarchy and discuss the evidence behind prostate CSCs and their inherent resistance to conventional cancer therapies. The known and proposed roles of the ETS family of transcription factors in prostate epithelial cell differentiation and regulation of the CSC phenotype will be discussed, as well as how they might be targeted for therapy.

Hierarchical transcriptional profile of urothelial cells development and differentiation

The urothelial lining of the lower urinary tract is the most efficient permeability barrier in animals, exhibiting a highly differentiated phenotype and a remarkable regenerative capacity upon wounding. During development and possibly during repair, cells undergo a sequence of hierarchical transcriptional events that mark the transition of these cells from the least differentiated urothelial phenotype characteristic of the basal cell layer, to the most differentiated cellular phenotype characteristic of the superficial cell layer. Unraveling normal urothelial differentiation program is essential to uncover the underlying causes of many congenital abnormalities and for the development of an appropriate differentiation niche for stem cells, for future use in urinary tract tissue engineering and organ reconstruction. Kruppel like factor-5 appears to be at the top of the hierarchy activating several downstream transcription factors, the most prominent of which is peroxisome proliferator activator receptor-γ. Eventually those lead to the activation of transcription factors that directly regulate the expression of uroplakin proteins along with other proteins that mediate the permeability function of the urothelium. In this review, we discuss the most recent findings in the area of urothelial cellular differentiation and transcriptional regulation, aiming for a comprehensive overview that aids in a refined understanding of this process.

ELF3 modulates type II collagen gene (COL2A1) transcription in chondrocytes by inhibiting SOX9-CBP/p300-driven histone acetyltransferase activity

AIM

We showed previously that E74-like factor 3 (ELF3) protein levels are increased in osteoarthritic (OA) cartilage, that ELF3 accounts for inflammatory cytokine-driven MMP13 gene expression, and that, upon induction by interleukin-1β, ELF3 binds to the COL2A1 promoter and suppresses its activity in chondrocytes. Here, we aimed to further investigate the mechanism/s by which ELF3 represses COL2A1 transcription in chondrocytes.

METHODS AND RESULTS

We report that ELF3 inhibits Sox9-driven COL2A1 promoter activity by interfering with the activator functions of CBP/300 and Sox9. Co-transfection of the pGL2B-COL2A1 (-577/+3428 bp) reporter construct with Sox9 and with Sox5 and/or Sox6 increased COL2A1 promoter activity, and ELF3 overexpression significantly reduced the promoter transactivation. Co-transfection of ELF3 with the pLuc 4x48 enhancer construct, containing the 89-bp COL2A1 promoter and lacking the previously defined ELF3 binding sites, decreased both basal and Sox9-driven promoter activity. Co-transfection of ELF3 with a Gal4 reporter construct also inhibited Gal4-Sox9-driven transactivation, suggesting that ELF3 directly interacts with Sox9. Using truncated Sox9 fragments, we found that ELF3 interacts directly with the HMG domain of Sox9. Importantly, overexpression of ELF3 significantly decreased Sox9/CBP-dependent HAT activity. Finally, we show evidence that increased ELF3 mRNA expression in OA chondrocytes correlates with hypermethylation of the proximal promoter, suggesting that ELF3 transcription is subjected to epigenetic control in OA disease.

CONCLUSION

Our results highlight the contribution of ELF3 to transcriptional regulation of COL2A1 and its potential role in OA disease, and uncover epigenetic mechanisms at play in the regulation of ELF3 and its downstream targets in articular chondrocytes.

A novel regulatory relationship between RIPK4 and ELF3 in keratinocytes

Keratinocytes are central to the barrier functions of surface epithelia, such as the gingiva and epidermis. RIPK4 is a key regulator of keratinocyte differentiation; however, the signalling pathways in which it functions remain poorly defined. In this study, we identified a regulatory relationship between RIPK4 and ELF3, an ETS family transcription factor. RIPK4 was shown to be important for the upregulation of ELF3 gene expression by the PKC agonist PMA in both oral and epidermal keratinocytes. RIPK4 promotes keratinocyte differentiation in part by phosphorylating and thereby activating the IRF6 transcription factor. Significantly, silencing of IRF6 inhibited the PMA-inducible expression of ELF3. A role for the GRHL3 transcription factor, a downstream target gene of IRF6, in the regulation of ELF3 expression was similarly demonstrated. ELF3 has previously been shown to regulate the expression of SPPR1A and SPRR1B, small proline-rich proteins that contribute to the cornification of keratinocytes. Consistently, RIPK4 and IRF6 were important for the PMA-inducible expression of SPRR1A and SPRR1B. They were also important for the upregulation of TGM1, a transglutaminase that catalyses the cross-linking of proteins, including small proline-rich proteins, during keratinocyte cornification. RIPK4 was also shown to upregulate the expression of TGM2 independently of IRF6. Collectively, our findings position RIPK4 upstream of a hierarchal IRF6-GRHL3-ELF3 transcription factor pathway in keratinocytes, as well as provide insight into a potential role for RIPK4 in the regulation of keratinocyte cornification.

ESE-1 in Early Development: Approaches for the Future

E26 transformation-specific (Ets) family of transcription factors are characterized by the presence of Ets-DNA binding domain and have been found to be highly involved in hematopoiesis and various tissue differentiation. ESE-1, or Elf3 in mice, is a member of epithelium-specific Ets sub-family which is most prominently expressed in epithelial tissues such as the gut, mammary gland, and lung. The role of ESE-1 during embryogenesis had long been alluded from 30% fetal lethality in homozygous knockout mice and its high expression in preimplantation mouse embryos, but there has been no in-depth of analysis of ESE-1 function in early development. With improved proteomics, gene editing tools and increasing knowledge of ESE-1 function in adult tissues, we hereby propose future research directions for the study of ESE-1 in embryogenesis, including studying its regulation at the protein level and at the protein family level, as well as better defining the developmental phase under investigation. Understanding the role of ESE-1 in early development will provide new insights into its involvement in tissue regeneration and cancer, as well as how it functions with other Ets factors as a protein family.

E74-like factor 3 and nuclear factor-κB regulate lipocalin-2 expression in chondrocytes

KEY POINTS

E74-like factor 3 (ELF3) is a transcription factor regulated by inflammation in different physio-pathological situations. Lipocalin-2 (LCN2) emerged as a relevant adipokine involved in the regulation of inflammation. In this study we showed for the first time the involvement of ELF3 in the control of LCN2 expression and its cooperation with nuclear factor-κB (NFκB). Our results will help to better understand of the role of ELF3, NFκB and LCN2 in the pathophysiology of articular cartilage.

ABSTRACT

E74-like factor 3 (ELF3) is a transcription factor induced by inflammatory cytokines in chondrocytes that increases gene expression of catabolic and inflammatory mediators. Lipocalin 2 (LCN2) is a novel adipokine that negatively impacts articular cartilage, triggering catabolic and inflammatory responses in chondrocytes. Here, we investigated the control of LCN2 gene expression by ELF3 in the context of interleukin 1 (IL-1)-driven inflammatory responses in chondrocytes. The interaction of ELF3 and nuclear factor-κB (NFκB) in modulating LCN2 levels was also explored. LCN2 mRNA and protein levels, as well those of several other ELF3 target genes, were determined by RT-qPCR and Western blotting. Human primary chondrocytes, primary chondrocytes from wild-type and Elf3 knockout mice, and immortalized human T/C-28a2 and murine ATDC5 cell lines were used in in vitro assays. The activities of various gene reporter constructs were evaluated by luciferase assays. Gene overexpression and knockdown were performed using specific expression vectors and siRNA technology, respectively. ELF3 overexpression transactivated the LCN2 promoter and increased the IL-1-induced mRNA and protein levels of LCN2, as well as the mRNA expression of other pro-inflammatory mediators, in human and mouse chondrocytes. We also identified a collaborative loop between ELF3 and NFκB that amplifies the induction of LCN2. Our findings show a novel role for ELF3 and NFκB in the induction of the pro-inflammatory adipokine LCN2, providing additional evidence of the interaction between ELF3 and NFκB in modulating inflammatory responses, and a better understanding of the mechanisms of action of ELF3 in chondrocytes.

Intrinsic Defect in Keratinocyte Function Leads to Inflammation in Hidradenitis Suppurativa

Hidradenitis suppurativa (HS) is a chronic, inflammatory, debilitating, follicular disease of the skin. Despite a high prevalence in the general population, the physiopathology of HS remains poorly understood. The use of antibiotics and immunosuppressive agents for therapy suggests a deregulated immune response to microflora. Using cellular and gene expression analyses, we found an increased number of infiltrating CD4(+) T cells secreting IL-17 and IFN-γ in perilesional and lesional skin of patients with HS. By contrast, IL-22-secreting CD4(+) T cells are not enriched in HS lesions contrasting with increased number of those cells in the blood of patients with HS. We showed that keratinocytes isolated from hair follicles of patients with HS secreted significantly more IL-1β, IP-10, and chemokine (C-C motif) ligand 5 (RANTES) either constitutively or on pattern recognition receptor stimulations. In addition, they displayed a distinct pattern of antimicrobial peptide production. These findings point out a functional defect of keratinocytes in HS leading to a balance prone to inflammatory responses. This is likely to favor a permissive environment for bacterial infections and chronic inflammation characterizing clinical outcomes in patients with HS.

A transcriptional repressive role for epithelial-specific ETS factor ELF3 on oestrogen receptor alpha in breast cancer cells

Oestrogen receptor-α (ERα) is a ligand-dependent transcription factor that primarily mediates oestrogen (E2)-dependent gene transcription required for mammary gland development. Coregulators critically regulate ERα transcription functions by directly interacting with it. In the present study, we report that ELF3, an epithelial-specific ETS transcription factor, acts as a transcriptional repressor of ERα. Co-immunoprecipitation (Co-IP) analysis demonstrated that ELF3 strongly binds to ERα in the absence of E2, but ELF3 dissociation occurs upon E2 treatment in a dose- and time-dependent manner suggesting that E2 negatively influences such interaction. Domain mapping studies further revealed that the ETS (E-twenty six) domain of ELF3 interacts with the DNA binding domain of ERα. Accordingly, ELF3 inhibited ERα’s DNA binding activity by preventing receptor dimerization, partly explaining the mechanism by which ELF3 represses ERα transcriptional activity. Ectopic expression of ELF3 decreases ERα transcriptional activity as demonstrated by oestrogen response elements (ERE)-luciferase reporter assay or by endogenous ERα target genes. Conversely ELF3 knockdown increases ERα transcriptional activity. Consistent with these results, ELF3 ectopic expression decreases E2-dependent MCF7 cell proliferation whereas ELF3 knockdown increases it. We also found that E2 induces ELF3 expression in MCF7 cells suggesting a negative feedback regulation of ERα signalling in breast cancer cells. A small peptide sequence of ELF3 derived through functional interaction between ERα and ELF3 could inhibit DNA binding activity of ERα and breast cancer cell growth. These findings demonstrate that ELF3 is a novel transcriptional repressor of ERα in breast cancer cells. Peptide interaction studies further represent a novel therapeutic option in breast cancer therapy.

Mechanism(S) Involved in the Colon-Specific Expression of the Thiamine Pyrophosphate (Tpp) Transporter

Microbiota of the large intestine synthesizes considerable amount of vitamin B1 (thiamine) in the form of thiamine pyrophosphate (TPP). We have recently demonstrated the existence of an efficient and specific carrier-mediated uptake process for TPP in human colonocytes, identified the TPP transporter (TPPT) involved (product of the SLC44A4 gene), and shown that expression of TPPT along the gastrointestinal (GI) tract is restricted to the colon. Our aim in this study was to determine the molecular basis of the colon-specific expression of TPPT focusing on a possible epigenetic mechanism. Our results showed that the CpG island predicted in the SLC44A4 promoter is non-methylated in the human colonic epithelial NCM460 cells, but is hyper-methylated in the human duodenal epithelial HuTu80 cells (as well as in the human retinal pigment epithelial ARPE19 cells). In the mouse (where TPPT expression in the GI tract is also restricted to the colon), the CpG island predicted in the Slc44a4 promoter is non-methylated in both the jejunum and colon, thus arguing against possible contribution of DNA methylation in the colon-specific expression of TPPT. A role for histone modifications in the tissue-specific pattern of Slc44a4 expression, however, was suggested by the findings that in mouse colon, histone H3 in the 5’-regulatory region of Slc44a4 is tri-methylated at lysine 4 and acetylated at lysine 9, whereas the tri-methylation at lysine 27 modification was negligible. In contrast, in the mouse jejunum, histone H3 is hyper-trimethylated at lysine 27 (repressor mark). Similarly, possible involvement of miRNA(s) in the tissue-specific expression of TPPT was also suggested by the findings that the 3’-UTR of SLC44A4 is targeted by specific miRNAs/RNA binding proteins in non-colonic, but not in colonic, epithelial cells. These studies show, for the first time, epigenetic mechanisms (histone modifications) play a role in determining the tissue-specific pattern of expression of TPPT in the GI tract.

Pathophysiology of osteoarthritis: canonical NF-κB/IKKβ-dependent and kinase-independent effects of IKKα in cartilage degradation and chondrocyte differentiation

Osteoarthritis (OA), a whole-joint disease driven by abnormal biomechanics and attendant cell-derived and tissue-derived factors, is a rheumatic disease with the highest prevalence, representing a severe health burden with a tremendous economic impact. Members of the nuclear factor κB (NF-κB) family orchestrate mechanical, inflammatory and oxidative stress-activated processes, thus representing a potential therapeutic target in OA disease. The two pivotal kinases, IκB kinase (IKK) α and IKKβ, activate NF-κB dimers that might translocate to the nucleus and regulate the expression of specific target genes involved in extracellular matrix remodelling and terminal differentiation of chondrocytes. IKKα, required for the activation of the so-called non-canonical pathway, has a number of NF-κB-independent and kinase-independent functions in vivo and in vitro, including controlling chondrocyte hypertrophic differentiation and collagenase activity. In this short review, we will discuss the role of NF-κB signalling in OA pathology, with emphasis on the functional effects of IKKα that are independent of its kinase activity and NF-κB activation.

Epithelium-Specific Ets-Like Transcription Factor 1, ESE-1, Regulates ICAM-1 Expression in Cultured Lung Epithelial Cell Lines

Cystic fibrosis (CF) patients suffer from chronic airway inflammation with excessive neutrophil infiltration. Migration of neutrophils to the lung requires chemokine and cytokine signaling as well as cell adhesion molecules, such as intercellular adhesion molecule-1 (ICAM-1), which plays an important role in mediating adhesive interactions between effector and target cells in the immune system. In this study, we investigated the relationship between ICAM-1 and epithelium-specific ETS-like transcription factor 1 (ESE-1) and found that ICAM-1 expression is upregulated in cell lines of CF (IB3-1) as well as non-CF (BEAS-2B and A549) epithelial origin in response to inflammatory cytokine stimulation. Since ESE-1 is highly expressed in A549 cells without stimulation, we examined the effect of ESE-1 knockdown on ICAM-1 expression in these cells. We found that ICAM-1 expression was downregulated when ESE-1 was knocked down in A549 cells. We also tested the effect of ESE-1 knockdown on cell-cell interactions and demonstrate that the knocking down ESE-1 in A549 cells reduce their interactions with HL-60 cells (human promyelocytic leukemia cell line). These results suggest that ESE-1 may play a role in regulating airway inflammation by regulating ICAM-1 expression.

Dissecting the calcium-induced differentiation of human primary keratinocytes stem cells by integrative and structural network analyses

The molecular details underlying the time-dependent assembly of protein complexes in cellular networks, such as those that occur during differentiation, are largely unexplored. Focusing on the calcium-induced differentiation of primary human keratinocytes as a model system for a major cellular reorganization process, we look at the expression of genes whose products are involved in manually-annotated protein complexes. Clustering analyses revealed only moderate co-expression of functionally related proteins during differentiation. However, when we looked at protein complexes, we found that the majority (55%) are composed of non-dynamic and dynamic gene products ('di-chromatic'), 19% are non-dynamic, and 26% only dynamic. Considering three-dimensional protein structures to predict steric interactions, we found that proteins encoded by dynamic genes frequently interact with a common non-dynamic protein in a mutually exclusive fashion. This suggests that during differentiation, complex assemblies may also change through variation in the abundance of proteins that compete for binding to common proteins as found in some cases for paralogous proteins. Considering the example of the TNF-α/NFκB signaling complex, we suggest that the same core complex can guide signals into diverse context-specific outputs by addition of time specific expressed subunits, while keeping other cellular functions constant. Thus, our analysis provides evidence that complex assembly with stable core components and competition could contribute to cell differentiation.

The uncovering of ESE-1 in human neutrophils: implication of its role in neutrophil function and survival

Epithelium-specific Ets transcription factor 1 (ESE-1) is a member of the E26 transformation-specific family of transcription factors that has an epithelial-restricted constitutive expression but is induced by inflammatory stimuli in non-epithelial cells. Here we report that ESE-1 is constitutively expressed in human, but not in murine, neutrophils and that ESE-1 is modestly upregulated in septic patient neutrophils. In normal human neutrophils, ESE-1 was detected at both RNA and protein levels but was found to be an unstable nuclear protein ex vivo. ESE-1 transcription was also induced during all-trans retinoic acid-mediated HL-60 differentiation, a human promyelocytic cell line often used as an in vitro model of human neutrophils. Elf3-/- mice had normal neutrophils but a reduced number of circulating B-lymphocytes. These findings indicate a potential role of ESE-1 in regulating human neutrophil differentiation and function, and that it has different roles in the immune system of different species.

Transcriptional regulators of claudins in epithelial tight junctions

Human gastrointestinal tract is covered by a monolayer of specialized epithelial cells that constitute a protective barrier surface to external toxic and infectious agents along with metabolic and digestive functions. Intercellular junctions, among epithelial cells, such as desmosomes, adherens, gap, and tight junctions (TJs), not only provide mechanical integrity but also limit movement of molecules across the monolayer. TJ is a complex structure composed of approximately 35 different proteins that interact with each other at the apical side of two adjacent epithelial cells. Claudin family proteins are important members of TJ with so far 24 known isoforms in different species. Claudins are structural proteins of TJ that help to control the paracellular movement by forming fence and barrier across the epithelial monolayer. Altered function of claudins is implicated in different form of cancers, inflammatory bowel diseases (IBDs), and leaky diarrhea. Based on their significant role in the molecular architecture of TJ, diversity, and disease association, further understanding about claudin family proteins and their genetic/epigenetic regulators is indispensable.

Regulation of basal promoter activity of the human thiamine pyrophosphate transporter SLC44A4 in human intestinal epithelial cells

Microbiota of the large intestine synthesize considerable amount of vitamin B1 in the form of thiamine pyrophosphate (TPP). There is a specific high-affinity regulated carrier-mediated uptake system for TPP in human colonocytes (product of the SLC44A4 gene). The mechanisms of regulation of SLC44A4 gene expression are currently unknown. In this study, we characterized the SLC44A4 minimal promoter region and identified transcription factors important for basal promoter activity in colonic epithelial cells. The 5'-regulatory region of the SLC44A4 gene (1,022 bp) was cloned and showed promoter activity upon transient transfection into human colonic epithelial NCM460 cells. With the use of a series of 5'- and 3'-deletion luciferase reporter constructs, the minimal genomic region that required basal transcription of the SLC44A4 gene expression was mapped between nucleotides -178 and +88 (using the distal transcriptional start site as +1). Mutational analysis performed on putative cis-regulatory elements established the involvement of ETS/ELF3 [E26 transformation-specific sequence (ETS) proteins], cAMP-responsive element (CRE), and SP1/GC-box sequence motifs in basal SLC44A4 promoter activity. By means of EMSA, binding of ELF3 and CRE-binding protein-1 (CREB-1) transcription factors to the SLC44A4 minimal promoter was shown. Contribution of CREB into SLC44A4 promoter activity was confirmed using NCM460 cells overexpressing CREB. We also found high expression of ELF3 and CREB-1 in colonic (NCM460) compared with noncolonic (ARPE19) cells, suggesting their possible contribution to colon-specific pattern of SLC44A4 expression. This study represents the first characterization of the SLC44A4 promoter and reports the importance of both ELF3 and CREB-1 transcription factors in the maintenance of basal promoter activity in colonic epithelial cells.

Epithelium-Specific ETS (ESE)-1 upregulated GP73 expression in hepatocellular carcinoma cells

Background

Golgi protein-73 (GP73) is a Golgi transmembrane glycoprotein elevated in numerous liver diseases. Clinically, GP73 is strongly elevated in the serum of HCC patients and is thus regarded as a novel potential biomarker for HCC. However, the mechanism leading to GP73 dysregulation in liver diseases remains unknown.

Results

This study determined that epithelium-specific ETS (ESE)-1, an epithelium-specific transcription factor, and GP73 expressions were induced by IL-1β stimulation in vitro, and both were triggered during liver inflammation in vivo. In hepatocellular carcinoma cells, the overexpression of ESE-1 induced GP73 expression, whereas its knock-down did the opposite. Mechanistically, ESE-1 activated GP73 expression by directly binding to its promoter.

Conclusions

Our findings supported a novel paradigm for ESE-1 as a transcriptional mediator of GP73. This study provided a possible mechanism for GP73 upregulation in liver diseases.

Electronic supplementary material

The online version of this article (doi:10.1186/2045-3701-4-76) contains supplementary material, which is available to authorized users.

Epithelium specific ETS transcription factor, ESE-3, of Protobothrops flavoviridis snake venom gland transactivates the promoters of venom phospholipase A2 isozyme genes

Protobothrops flavoviridis (habu) (Crotalinae, Viperidae) is a Japanese venomous snake, and its venom contains the enzymes with a variety of physiological activities. The phospholipases A2 (PLA2s) are the major components and exert various toxic effects. They are expressed abundantly in the venom gland. It is thought that the venom gland-specific transcription factors play a key role for activation of PLA2 genes specifically expressed in the venom gland. Thus, the full-length cDNA library for P. flavoviridis venom gland after milking of the venom was made to explore the transcription factors therein. As a result, three cDNAs encoding epithelium-specific ETS transcription factors (ESE)-1, -2, and -3 were obtained. Among them, ESE-3 was specifically expressed in the venom gland and activated the proximal promoters of venom PLA2 genes, which are possibly regarded as the representatives of the venom gland-specific protein genes in P. flavoviridis. Interestingly, the binding specificity of ESE-3 to the ETS binding motif located near TATA box is well correlated with transcriptional activities for the venom PLA2 genes. This is the first report that venom gland-specific transcription factor could actually activate the promoters of the venom protein genes.