Zinc finger transcription factor Egr-1 activates Flt-1 gene expression in THP-1 cells on induction for macrophage differentiation

Ginkgo biloba extracts improve choroidal circulation leading to suppression of myopia in mice

Myopia is becoming more common across the world, necessitating the development of preventive methods. We investigated the activity of early growth response 1 (EGR-1) protein and discovered that Ginkgo biloba extracts (GBEs) activated EGR-1 in vitro. In vivo, C57BL/6 J mice were fed either normal or 0.0667% GBEs (200 mg/kg) mixed chow (n = 6 each), and myopia was induced with - 30 diopter (D) lenses from 3 to 6 weeks of age. Refraction and axial length were measured by an infrared photorefractor and an SD-OCT system, respectively. In lens-induced myopia mice, oral GBEs significantly improved refractive errors (- 9.92 ± 1.53 D vs. - 1.67 ± 3.51 D, p < 0.001) and axial elongation (0.22 ± 0.02 mm vs. 0.19 ± 0.02 mm, p < 0.05). To confirm the mechanism of GBEs in preventing myopia progression, the 3-week-old mice were divided into normally fed with either myopic-induced or non-myopic-induced groups and GBEs fed with either myopic-induced or non-myopic-induced groups (n = 10 each). Choroidal blood perfusion was measured with optical coherence tomography angiography (OCTA). In both non-myopic induced groups, compared to normal chow, oral GBEs significantly improved choroidal blood perfusion (8.48 ± 15.75%Area vs. 21.74 ± 10.54%Area, p < 0.05) and expression of Egr-1 and endothelial nitric oxide synthase (eNOS) in the choroid. In both myopic-induced groups, compared to normal chow, oral GBEs also improved choroidal blood perfusion (- 9.82 ± 9.47%Area vs. 2.29 ± 11.84%Area, p < 0.05) and was positively correlated with the change in choroidal thickness. These findings suggest that GBEs may inhibit the progression of myopia by improving choroidal blood perfusion.

Equation learning to identify nano-engineered particle-cell interactions: an interpretable machine learning approach

Designing nano-engineered particles capable of the delivery of therapeutic and diagnostic agents to a specific target remains a significant challenge. Understanding how interactions between particles and cells are impacted by the physicochemical properties of the particle will help inform rational design choices. Mathematical and computational techniques allow for details regarding particle-cell interactions to be isolated from the interwoven set of biological, chemical, and physical phenomena involved in the particle delivery process. Here we present a machine learning framework capable of elucidating particle-cell interactions from experimental data. This framework employs a data-driven modelling approach, augmented by established biological knowledge. Crucially, the model of particle-cell interactions learned by the framework can be interpreted and analysed, in contrast to the 'black box' models inherent to other machine learning approaches. We apply the framework to association data for thirty different particle-cell pairs. This library of data contains both adherent and suspension cell lines, as well as a diverse collection of particles. We consider hyperbranched polymer and poly(methacrylic acid) particles, from 6 nm to 1032 nm in diameter, with small molecule, monoclonal antibody, and peptide surface functionalisations. Despite the diverse nature of the experiments, the learned models of particle-cell interactions for each particle-cell pair are remarkably consistent: out of 2048 potential models, only four unique models are learned. The models reveal that nonlinear saturation effects are a key feature governing particle-cell interactions. Further, the framework provides robust estimates of particle performance, which facilitates quantitative evaluation of particle design choices.

Analysis of the polarization states of the alveolar macrophages in chronic obstructive pulmonary disease samples based on miRNA-mRNA network signatures

Background

Multiple gene expression studies have been performed to investigate the biomarkers of chronic obstructive pulmonary disease (COPD). However, few studies have related COPD to macrophage cells.

Methods

The gene expression levels of clinical samples of COPD smokers (COPD; n=6), healthy smokers (Smoke; n=11), and never smokers (Never; n=4) were downloaded from the Gene Expression Omnibus (GEO) repository of GSE124180. The expression levels of messenger RNAs (mRNAs) and microRNAs (miRNAs) in macrophage cells of M0 (n=7), M1 (n=7), and M2 (n=7) were downloaded from the GEO repository of GSE46903 and GSE51307. Differentially expressed (DE) mRNAs (DEmRNAs) were identified by edgeR and GEO2R, with an adjusted P value <0.05 and |log₂fold change (FC)| ≥1 chosen as the cut-off threshold. The potential target genes of miRNA were identified using miRanda (v3.3a) and TargetScan (v6.0) with default settings. Gene Ontology (GO) and Reactome pathway analyses were performed.

Results

The composition of macrophages was quite different between COPD, Never, and Smoke samples. The proportion of M1 cells was lower than that of M0 and M2 cells in Smokers and COPD samples. Most of the genes specifically up-regulated in M1 are related to inflammation/immunity. The expression levels of miR-30a-5p, miR-200c-3p, miR-20b-5p, miR-199b-5p, and miR-301b-3p in M1 macrophages were all lower than that of M0. Their expression levels in M2 macrophages compared with M1 varied, with higher expression in miR-30a-5p, miR-20b-5p, and lower expression in miR-200c-3p, and miR-301b-3p. The mRNAs of the fms related receptor tyrosine kinase 1 (FLT1), cardiotrophin like cytokine factor 1 (CLCF1), phosphodiesterase 4D (PDE4D), coagulation factor III, and tissue factor (F3) were dysregulated in COPD and macrophage cells.

Conclusions

The present study mined the miRNA-mRNA signature which might play an essential role in COPD and macrophage polarization.

Aberrant retinoic acid production in the decidua: Implications for pre-eclampsia

Fine-tuning of the endometrium during the evanescent 'window of implantation' relies upon an array of diverse and redundant signaling molecules, particularly the ovarian steroids E2 and P4, but also growth factors, eicosanoids, and vitamins including the vitamin A compounds (retinoids). Pregnancy complications such as preeclampsia (PE) can result from aberrations in the production or function of these molecules that arise during this critical period of decidual development. Such aberrations may be reflected by incomplete decidualization, reduced spiral artery modification, and/or loss of immune tolerance to the developing fetus. Our understanding of the role of the active retinoid metabolite all-trans retinoic acid (RA) in maintaining immune balance in certain tissues, along with data describing its role in decidualization, present a compelling argument that aberrant RA signaling in the decidua can play a significant role in the etiology of PE. Recent findings that decidualization and expression of the anti-angiogenic gene product, 'soluble fms-like tyrosine kinase-1' (sFLT1) are negatively correlated and that sFLT1 expression is directly inhibited by RA, provide additional evidence of the critical role of this retinoid in regulating early vascular development in the decidua. This review provides insight into the production and function of RA in the decidua and how modifications in its metabolism and signaling might lead to certain pregnancy disorders such as PE.

Retinoic Acid Is a Negative Regulator of sFLT1 Expression in Decidual Stromal Cells, and Its Levels Are Reduced in Preeclamptic Decidua

sFLT1 (soluble VEGF [vascular endothelial growth factor] receptor-1) levels are increased in preeclampsia-a pathological condition of pregnancy. The mechanism of sFLT1 overexpression by gestational tissues, particularly the decidua, remains unknown. Mass spectrometry measurement of the active retinoid metabolite, all-trans retinoic acid (RA), showed significantly lower levels of RA in preeclamptic versus normotensive decidua. In this study, we investigated the involvement of RA in regulating decidual sFLT1 expression. When decidual stromal cells (DSCs) isolated from the decidua basalis of normotensive and preeclampsia placentas were treated with BMS493-a pan-RAR (RA nuclear receptor) antagonist-upregulation of sFLT1 expression was observed. Conversely, treatment with RA resulted in downregulation of sFLT1 in normotensive DSCs and preeclampsia DSCs. Unlike treatment with cAMP, which induces decidualization while downregulating sFLT1, RA treatment did not alter DSC expression of prolactin-a marker of decidualization-or FOXO1 (forkhead box protein 01)-a transcription factor required for prolactin upregulation. TFAP2A (transcription factor AP-2-alpha [activating enhancer-binding protein 2 alpha]), a different transcription factor was upregulated in normotensive DSCs but not in preeclampsia DSCs after RA treatment. Collectively, our data show that RA suppresses sFLT1 expression in DSCs independently of cellular decidualization. These findings suggest that reduced decidual RA levels may contribute to preeclampsia pathogenesis by allowing sFLT1 accumulation at the maternal-fetal interface.

Oral crocetin administration suppressed refractive shift and axial elongation in a murine model of lens-induced myopia

Increased global incidence of myopia necessitates establishment of therapeutic approaches against its progression. To explore agents which may control myopia, we screened 207 types of natural compounds and chemical reagents based on an activity of a myopia suppressive factor, early growth response protein 1 (Egr-1) in vitro. Among the candidates, crocetin showed the highest and dose-dependent activation of Egr-1. For in vivo analysis, experimental myopia was induced in 3-week-old C57BL/6 J mice with −30 diopter (D) lenses for 3 weeks. Animals were fed with normal or mixed chow containing 0.003% (n = 19) and 0.03% (n = 7) of crocetin during myopia induction. Refraction and axial length were measured at 3-week-old and the 6-week-old with an infrared photorefractor and a SD-OCT system. Compared to controls (n = 14), crocetin administration showed a significant smaller change of refractive errors (−13.62 ± 8.14 vs +0.82 ± 5.81 D for 0.003%, p < 0.01, −2.00 ± 4.52 D for 0.03%, p < 0.01) and axial elongation (0.27 ± 0.03 vs 0.22 ± 0.04 mm for 0.003%, p < 0.01, 0.23 ± 0.05 mm for 0.03%, p < 0.05). These results suggest that a dietary factor crocetin may have a preventive effect against myopia progression.

Correlations of the expressions of c-Jun and Egr-1 proteins with clinicopathological features and prognosis of patients with nasopharyngeal carcinoma

This study intended to explore the correlation of the expressions of c-Jun and Egr-1 proteins with clinicopathological features and prognosis of patients with nasopharyngeal carcinoma (NPC). From January 2008 to January 2011, 123 NPC patients and 59 patients with chronic rhinitis were enrolled in this study. Fresh NPC and normal nasopharynx tissue specimens were obtained during surgery. Immunohistochemistry (IHC) was adopted to determine the positive expressions of the c-Jun and Egr-1 proteins. A 5-year clinical follow-up was conducted on all NPC patients. The Kaplan-Meier survival curve and Cox regression model were used for survival analysis. Compared with normal nasopharynx tissues, c-Jun expression was up-regulated but Egr-1 expression was down-regulated in NPC tissues. NPC patients with stage T3-T4 or stage III-IV had higher positive rates of c-Jun expression than those with stage T1-T2 or stage I-II. However, the positive rates of Egr-1 expression was higher in patients with stage T1-T2 or stage III-IV than those with stage T3-T4 or stage I-II. The survival rate of NPC patients with high c-Jun expression was lower than those with low/negative c-Jun expression, while the survival rate of NPC patients with high Egr-1 expression was higher than those with low/negative Egr-1 expression. The Cox regression analysis revealed that stage T3-T4, high c-Jun expression, and low Egr-1 expression were risk factors for poor prognosis of NPC patients. In conclusion, our study suggests that the c-Jun and Egr-1 proteins can serve as novel potential biomarkers for the early diagnosis and prognosis prediction of NPC.

Topological organization and dynamic regulation of human tRNA genes during macrophage differentiation

Background

The human genome is hierarchically organized into local and long-range structures that help shape cell-type-specific transcription patterns. Transfer RNA (tRNA) genes (tDNAs), which are transcribed by RNA polymerase III (RNAPIII) and encode RNA molecules responsible for translation, are dispersed throughout the genome and, in many cases, linearly organized into genomic clusters with other tDNAs. Whether the location and three-dimensional organization of tDNAs contribute to the activity of these genes has remained difficult to address, due in part to unique challenges related to tRNA sequencing. We therefore devised integrated tDNA expression profiling, a method that combines RNAPIII mapping with biotin-capture of nascent tRNAs. We apply this method to the study of dynamic tRNA gene regulation during macrophage development and further integrate these data with high-resolution maps of 3D chromatin structure.

Results

Integrated tDNA expression profiling reveals domain-level and loop-based organization of tRNA gene transcription during cellular differentiation. tRNA genes connected by DNA loops, which are proximal to CTCF binding sites and expressed at elevated levels compared to non-loop tDNAs, change coordinately with tDNAs and protein-coding genes at distal ends of interactions mapped by in situ Hi-C. We find that downregulated tRNA genes are specifically marked by enhanced promoter-proximal binding of MAF1, a transcriptional repressor of RNAPIII activity, altogether revealing multiple levels of tDNA regulation during cellular differentiation.

Conclusions

We present evidence of both local and coordinated long-range regulation of human tDNA expression, suggesting the location and organization of tRNA genes contribute to dynamic tDNA activity during macrophage development.

Electronic supplementary material

The online version of this article (doi:10.1186/s13059-017-1310-3) contains supplementary material, which is available to authorized users.

Human macrophage ATP7A is localized in the trans-Golgi apparatus, controls intracellular copper levels, and mediates macrophage responses to dermal wounds

The copper transporter ATP7A has attracted significant attention since the discovery of its gene mutation leading to human Menkes disease. We previously reported that ATP7A is highly expressed in the human vasculature and identified a novel vascular function of ATP7A in modulation of the expression and activity of extracellular superoxide dismutase. We recently identified that ATP7A expression in THP-1 cells (a monocyte/macrophage model cell line) plays a role in the oxidation of low density lipoproteins, indicating that it is necessary to further investigate its expression and function in monocytes/macrophages. In the current study, we demonstrated the protein and mRNA expression of ATP7A in human peripheral blood mononuclear cell (PBMC)-derived macrophages and alveolar macrophages. ATP7A was strongly co-localized with the trans-Golgi apparatus in PBMC-derived macrophages. Intracellular copper, detected by synchrotron X-ray fluorescence microscopy, was found to be distributed to the nucleus and cytoplasm in human THP-1 cells. To confirm the role of endogenous ATP7A in macrophage copper homeostasis, we performed inductively coupled plasma mass spectrometry in murine peritoneal macrophages, which showed markedly increased intracellular copper levels in macrophages isolated from ATP7A-deficient mice versus control mice. Moreover, the role of ATP7A in regulating macrophage responses to dermal wounds was studied by introduction of control and ATP7A-downregulated THP-1 cells into dermal wounds of nude mice. Infiltration of THP-1 cells into the wounded area (detected by expression of human macrophage markers MAC2 and CD68) was reduced in response to downregulation of ATP7A, hinting decreased macrophage accumulation subsequent to dermal wounds. In summary, alongside our previous studies, these findings indicate that human macrophage ATP7A is localized in the trans-Golgi apparatus, regulates intracellular copper levels, and mediates macrophage responses to a dermal wound.

Extracellular RNA promotes leukocyte recruitment in the vascular system by mobilising proinflammatory cytokines

Extracellular RNA (eRNA), released from cells under conditions of injury or vascular disease, acts as potent prothrombotic factor and promotes vascular hyperpermeability related to oedema formation in vivo. In this study, we aimed to investigate the mechanism by which eRNA triggers inflammatory processes, particularly associated with different steps of leukocyte recruitment. Using intravital microscopy of murine cremaster muscle venules, eRNA (but not DNA) significantly induced leukocyte adhesion and transmigration in vivo, which was comparable in its effects to the function of tumour-necrosis-factor-α (TNF-α). In vitro, eRNA promoted adhesion and transmigration of monocytic cells on and across endothelial cell monolayers. eRNA-induced monocyte adhesion in vitro was mediated by activation of the vascular endothelial growth factor (VEGF)/VEGF-receptor-2 system and was abolished by neutralising antibodies against intercellular adhesion molecule-1 or the β2-integrin Mac-1. Additionally, eRNA induced the release of TNF-α from monocytic cells in a time- and concentration-dependent manner, which involved activation of TNF-α-converting enzyme (TACE) as well as the nuclear factor κB signalling machinery. In vivo, inhibiton of TACE significantly reduced eRNA-induced leukocyte adhesion. Our findings present evidence that eRNA in connection with tissue/vascular damage provokes a potent inflammatory response by inducing leukocyte recruitment and by mobilising proinflammatory cytokines from monocytes.

Plant RMR proteins: unique vacuolar sorting receptors that couple ligand sorting with membrane internalization

In receptor-mediated sorting of soluble protein ligands in the endomembrane system of eukaryotic cells, three completely different receptor proteins for mammalian (mannose 6-phosphate receptor), yeast (Vps10p) and plant cells (vacuolar sorting receptor; VSR) have in common the features of pH-dependent ligand binding and receptor recycling. In striking contrast, the plant receptor homology-transmembrane-RING-H2 (RMR) proteins serve as sorting receptors to a separate type of vacuole, the protein storage vacuole, but do not recycle, and their trafficking pathway results in their internalization into the destination vacuole. Even though plant RMR proteins share high sequence similarity with the best-characterized mammalian PA-TM-RING family proteins, these two families of proteins appear to play distinctly different roles in plant and animal cells. Thus, this minireview focuses on this unique sorting mechanism and traffic of RMR proteins via dense vesicles in various plant cell types.

Early growth response protein 1 acts as an activator of SOX18 promoter

Sex-determining region Y box 18 (Sox18/SOX18) gene is an important regulator of vascular development playing a role in endothelial cell specification or differentiation, angiogenesis and atherogenesis. The aim of this study was to perform comprehensive functional characterization of the human SOX18 promoter, including determination of transcription start point (tsp) and identification of control elements involved in the regulation of SOX18 gene expression, with an emphasis on angiogenesis-related transcription factors. Analyses were performed in HeLa cells, representing a tumor cell line, and in EA.hy926 cells used as an endothelial model system. We have determined unique tsp of SOX18 gene, located 172 nucleotides upstream from ATG codon. Further, we have shown that SOX18 promoter region, -726 to -89 bp relative to tsp, contains positive cis-regulatory element(s) that stimulates SOX18 promoter activity, while region -89 to+166 represents the minimal promoter. Within this region we have recognized the presence of essential element(s), positioned from -89 to +29, which harbors cluster of three putative early growth response 1 (EGR1) binding sites. By in vitro binding assays and functional analyses we have shown that these three putative binding sites are functionally relevant and sufficient for EGR1-induced SOX18 transcription. Mutations of these binding sites significantly impaired activity of the SOX18 promoter, particularly in EA.hy926 cells, indicating the importance of these regulatory elements for SOX18 promoter activity in endothelial setting. By data presented in this study, we have established SOX18 as a novel target gene regulated by EGR1 transcription factor, thus providing the first functional link between two transcription factors previously shown to be involved in the control of angiogenesis.

Zinc protoporphyrin regulates cyclin D1 expression independent of heme oxygenase inhibition

Zinc protoporphyrin IX (ZnPP), an endogenous heme analogue that inhibits heme oxygenase (HO) activity, represses tumor growth. It can also translocate into the nucleus and up-regulate heme oxygenase 1 (HMOX1) gene expression. Here, we demonstrate that tumor cell proliferation was inhibited by ZnPP, whereas tin protoporphyrin (SnPP), another equally potent HO-1 inhibitor, had no effect. Microarray analysis on 128 tumorigenesis related genes showed that ZnPP suppressed genes involved in cell proliferation and angiogenesis. Among these genes, CYCLIN D1 (CCND1) was specifically inhibited as were its mRNA and protein levels. Additionally, ZnPP inhibited CCND1 promoter activity through an Sp1 and Egr1 overlapping binding site (S/E). We confirmed that ZnPP modulated the S/E site, at least partially by associating with Sp1 and Egr1 proteins rather than direct binding to DNA targets. Furthermore, administration of ZnPP significantly inhibited cyclin D1 expression and progression of a B-cell leukemia/lymphoma 1 tumor in mice by preferentially targeting tumor cells. These observations show HO independent effects of ZnPP on cyclin D1 expression and tumorigenesis.

[Genes that make the endothelial identity]

The endothelium is a tissue with a distinct identity due to the specific expression of molecular markers by endothelial cells. Further, the endothelium displays a structural heterogeneity illustrated by the expression of specific markers in arteries and in veins. Here, we present a review of the transcriptional and epigenetic mechanisms regulating the expression of the main markers of endothelial cells in man and mouse, demonstrating that there is no common and unique mechanism of specific expression of genes in these cells.

Suppressed NFAT-dependent VEGFR1 expression and constitutive VEGFR2 signaling in infantile hemangioma

Infantile hemangiomas are localized and rapidly growing regions of disorganized angiogenesis. We show that expression of vascular endothelial growth factor receptor-1 (VEGFR1) in hemangioma endothelial cells (hemECs) and hemangioma tissue is markedly reduced compared to controls. Low VEGFR1 expression in hemECs results in VEGF-dependent activation of VEGFR2 and downstream signaling pathways. In hemECs, transcription of the gene encoding VEGFR1 (FLT1) is dependent on nuclear factor of activated T cells (NFAT). Low VEGFR1 expression in hemECs is caused by reduced activity of a pathway involving beta1 integrin, the integrin-like receptor tumor endothelial marker-8 (TEM8), VEGFR2 and NFAT. In a subset of individuals with hemangioma, we found missense mutations in the genes encoding VEGFR2 (KDR) and TEM8 (ANTXR1). These mutations result in increased interactions among VEGFR2, TEM8 and beta1 integrin proteins and in inhibition of integrin activity. Normalization of the constitutive VEGFR2 signaling in hemECs with soluble VEGFR1 or antibodies that neutralize VEGF or stimulate beta1 integrin suggests that local administration of these or similar agents may be effective in hemangioma treatment.

Transcription of PRDM1, the master regulator for plasma cell differentiation, depends on an SP1/SP3/EGR-1 GC-box

The positive regulatory domain containing 1, encoded by the PRDM1 gene, is a transcriptional repressor considered as a master regulator that is required and sufficient for plasma cell differentiation. In the present study we have performed sequence analysis of the upstream region of the human PRDM1 gene to detect the minimal promoter region necessary for PRDM1 gene transcription. This region comprises the region upstream of the initiation site, as well as the first exon. Collectively, deletion and mutation analysis in conjunction with luciferase reporter assays, EMSA and supershift assays identified a phylogenetically conserved GC-box as an essential element for PRDM1 expression. This GC-box element matches to a binding site for multiple transcription factors such as SP1 and SP3 isoforms as well as early growth response 1. Chromatin immunoprecipitation assays confirmed the in vivo binding capability of these factors to the human PRDM1 promoter. These studies together characterize for the first time the basal activity of the human PRDM1 promoter, through which several factors, including SP1, SP3 and early growth response 1, modulate its expression through a conserved GC-box.

Glucocorticoid-induced tumour necrosis factor receptor family related protein (GITR) mediates inflammatory activation of macrophages that can destabilize atherosclerotic plaques

Glucocorticoid-induced tumour necrosis factor receptor family related protein (GITR) is the 18th member of the tumour necrosis factor receptor superfamily (TNFRSF18) and is known to interact with its cognate ligand GITRL (TNFSF18). We investigated the potential role of GITR in the pro-inflammatory activation of macrophages. Immunohistochemistry and in situ hybridization analyses of human atherosclerotic plaques demonstrated that GITR and its ligand are expressed mainly in lipid-rich macrophages. We then investigated the role of GITR in human and mouse monocyte/macrophage functions. Stimulation of GITR caused nuclear factor (NF)-kappaB-dependent activation of matrix metalloproteinase-9 (MMP-9) and pro-inflammatory cytokine expression in both the human and mouse monocytic/macrophage cell lines, THP-1 and RAW264.7, respectively. These cellular responses were also observed when the THP-1 cells were treated with phorbol-12 myristate-13 acetate (PMA), which is known to induce macrophage differentiation. To demonstrate that these responses are not restricted to cultured cell lines, we tested primary macrophages. Both peritoneal and bone marrow-derived macrophages responded to GITR stimulation with induction of MMP-9 and tumour necrosis factor-alpha (TNF-alpha). Furthermore, the GITR staining pattern overlapped with those of MMP-9 and TNF-alpha in atherosclerotic plaques. These data indicate that GITR-mediated macrophage activation may promote atherogenesis via the induction of pro-atherogenic cytokines/chemokines, and destabilize the atherosclerotic plaques via the induction of the matrix-degrading enzyme, MMP-9.

Purification and characterization of C-terminal truncated forms of histone H2A in monocytic THP-1 cells

Histones are key components of chromatin. We investigated histone H2A-immunoreactive proteins in acute monocytic leukemia THP-1 cells using three polyclonal antibodies raised against peptides corresponding to distinct regions of H2A. Two unknown immunoreactive proteins (9- and 12-kDa proteins), H2A (14kDa) and ubiquitinated H2A (23kDa) were found in the cell lysates prepared by immediate direct addition of SDS-PAGE sample buffer to the cells as well as in the nuclear and chromatin fractions. However, they were not found in the cytoplasmic fraction. The unknown proteins were successfully purified by immunoaffinity chromatography from the cell nucleus extract and identified as 9-kDa H2A(1-87) and 12-kDa H2A(1-114), suggesting that both were produced by limited proteolysis of intact H2A(1-129). The truncated forms of H2A probably persisted as chromatin constituents, since the stability of H2A(1-87) in the chromatin fraction was sensitive to treatment with micrococcal nuclease, and H2A(1-114) was solubilized with lower ionic strength from the chromatin fraction obtained by micrococcal nuclease treatment. Truncated H2A proteins in THP-1 cells were transiently increased in amount by short-term treatment with phorbol 12-myristate 13-acetate or all-trans-retinoic acid, both of which induce macrophage-like differentiation. Furthermore, these increases were suppressed by preceding treatment with carbobenzoxy-l-leucyl-l-leucyl-l-leucinal (MG132) but not with carbobenzoxy-l-isoleucyl-gamma-t-butyl-l-glutamyl-l-alanyl-l-leucinal (PSI), both of which are generally known as proteasome inhibitors. Our results suggest that histone H2A is cleaved at least at two sites by protease(s) that remain obscure, and might affect chromatins in the early stage of THP-1 cell differentiation.

Zinc finger transcription factor Egr-1 is involved in stimulation of NHE2 gene expression by phorbol 12-myristate 13-acetate

The apical membrane Na(+)/H(+) exchanger isoforms NHE2 and NHE3 are involved in transepithelial Na(+) absorption in the intestine. However, they exhibit differences in their pattern of tissue expression and regulation of their activity by various molecular signals. To study the mechanisms involved in the transcriptional regulation of these genes, we characterized cis-acting elements within the human NHE2 promoter that regulate NHE2 promoter expression in C2BBe1 cells. A small DNA region (-85/+249) was involved in the regulation of basal transcriptional activity of the NHE2 promoter as determined by transient transfection assays. RT-PCR analysis showed that NHE2 mRNA was upregulated in response to phorbol 12-myristate 13-acetate (PMA). Results from actinomycin D-treated cells indicated that the regulation of the NHE2 gene by PMA occurs in part at the transcriptional level. Furthermore, PMA treatment led to a 100% increase in promoter activity through elements located on the -415/+249 DNA fragment. A PMA-induced nuclear factor that bound to the NHE2 promoter was identified as the transcription factor Egr-1. We identified two PMA response elements in the -415/+1 promoter region that bind to Sp1 and Sp3 in untreated nuclear extracts and to Egr-1 in PMA-treated nuclear extracts. In cotransfection experiments, Egr-1 was able to transactivate the NHE2 promoter. Our data indicate that Egr-1 may play a key role in regulated expression of the human NHE2 gene.

Chylomicron remnants regulate early growth response factor-1 in vascular smooth muscle cells

Early growth response factor-1 (Egr-1) is a zinc-finger transcription factor that induces genes that promote atherosclerosis. The goal of the present study was to determine whether Egr-1 expression is modulated by atherogenic, triglyceride rich lipoproteins known as chylomicron remnants. Chylomicron remnants induced Egr-1 mRNA and protein expression in rat cultured vascular smooth muscle cells (VSMCs) and activated extracellular signal-regulated kinase (ERK) 1/2 in VSMCs. Further, chylomicron remnant-induced Egr-1 expression was inhibited by PD98059, a selective inhibitor of MAPK kinase (MEK), suggesting that the action of chylomicron remnants on Egr-1 was dependent on the ERK/MEK pathway. Chylomicron remnants also induced mRNA expression of the pro-inflammatory cytokines, IL-2 and IFN-gamma in VSMCs. We conclude that chylomicron remnants act as atherogenic lipoproteins via induction of Egr-1 expression and via cytokine-mediated inflammation.

Sampling-dependent up-regulation of gene expression in sequential samples of human airway epithelial cells

As part of a study of in vivo gene expression levels in the human airway epithelium in response to chronic cigarette smoking, we have identified a number of genes whose expression levels are altered in a time-dependent fashion resulting from the procedure used to sample epithelial cells. Fiberoptic bronchoscopy and airway epithelium brushing were used to obtain independent samples from a single individual, 1st from the right lung, followed by sampling of the left lung. We observed that a specific subset of early response genes encoding proteins involved in transcription, signal transduction, cell cycle/growth, and apoptosis were significantly up-regulated in the left lung samples (the 2nd region to be sampled) compared with the right lung samples (the 1st region to be sampled). This response was due to the temporal nature of the sampling procedure and not to inherent gene expression differences between airway epithelium of the right and left lungs. When the order of sampling was reversed, with the left airway epithelium sampled 1st, the same subset of genes were up-regulated in the samples obtained from the right airway epithelium. The time-dependent up-regulation of these genes was likely in response to the stress of the procedure and/or the anesthesia used. Sampling-dependent uncertainty of gene expression is likely a general phenomenon relevant to the procedures used for obtaining biological samples, particularly in humans where the sampling procedures are dependent on ensuring comfort and safety.

Stretch-inducible Expression of the Angiogenic Factor CCN1 in Vascular Smooth Muscle Cells Is Mediated by Egr-1

CCN1 is an angiogenic factor that promotes cell adhesion, proliferation, and differentiation. CCN1-deficient mice suffer embryonic death because of vascular defects, demonstrating that CCN1 is required for vessel development. Because mechanical stretch may act as a trigger for vessel development, we investigated the impact of mechanical stretch on the regulatory mechanism of CCN1 expression. Mechanical stretch rapidly enhances CCN1 expression and release in vascular smooth muscle cells (VSMC) in vitro and CCN1 expression in murine aortic segments in vivo. Transfection experiments of VSMC with deletion constructs of the CCN1 promoter revealed the regulatory region responsible for the stretch-induced CCN1 expression in the approximately 200-bp promoter region upstream of the TATA-box containing potential binding sites for early growth response-1 (Egr-1), nuclear factor of activated T-cells and cAMP response element binding protein. Decoy oligonucleotides to Egr-1, but not to nuclear factor of activated T-cells or cAMP response element binding protein, abolished the stretch-induced transcription of CCN1. In addition, mutagenesis of the Egr-1 binding site within the CCN1 promoter completely blunted the stretch-induced activation of the promoter. Furthermore, mechanical stretch induced the expression and DNA-binding activity of Egr-1 in VSMC as demonstrated by Western blot and electromobility shift assay. Moreover, a pressure overload-dependent de novo synthesis of Egr-1 was observed after aortic banding. These findings indicate that mechanical stretch leads to enhanced expression of CCN1 via the mechanosensitive transcription factor Egr-1, suggesting a central role for mechanical stretch in the regulation of CCN1-dependent pro-angiogenic potency.

Decreased expression of early growth response-1 and its role in uterine leiomyoma growth

Expression of early growth response (Egr)-1, a transcriptional factor implicated in growth regulation, is suppressed in several malignant tumors. The present study investigated the expression of Egr-1 and related genes in uterine leiomyoma and normal myometrium to determine possible contributions of Egr-1 to neoplastic growth in leiomyoma cells. Levels of Egr-1 transcripts were decreased in all leiomyomas (n = 20) to approximately 10% of levels in corresponding myometrium, where basal expression was high. Preoperative leuprorelin acetate therapy increased levels of Egr-1 mRNA in normal myometrium only. Northern blot analysis using additional sample sets (n = 5) revealed the full-length Egr-1 transcript. Western blot analysis (n = 5) confirmed decreased expression of Egr-1 protein. Southern blot analysis of the Egr-1 gene and microsatellite analysis of the chromosomal location at 5q31 (D5S414, D5S500, and D5S476) revealed neither DNA recombination nor loss of heterozygosity in leiomyomas. Moreover, Egr-1 retained identical responsiveness to phorbol 12-myristate 13-acetate in primary cultures derived from both leiomyoma and normal tissues. Electrophoretic mobility shift analysis revealed that phorbol 12-myristate 13-acetate-induced Egr-1 in leiomyoma cells retained DNA binding ability. Egr-1 thus appears functionally intact in leiomyoma cells. Finally, consistent with the role of Egr-1 in growth inhibition, transfection of Egr-1 expression vector into a myometrial cell line (KW) that expresses low levels of Egr-1 and displays rapid growth inhibited thymidine uptake in these cells. Egr-1 may display tumor-suppressing activity and offers a potential target for leiomyoma management.

An angiogenic switch in breast cancer involves estrogen and soluble vascular endothelial growth factor receptor 1

Estrogen is involved in breast tumorigenesis, but the precise mechanisms for its oncogenic and angiogenic actions are poorly understood. Angiogenesis is regulated, in part, by these critical components: vascular endothelial growth factor (VEGF) and its two receptors (VEGFR-1 and VEGFR-2). VEGFR-2 is a positive angiogenic signal transducer, whereas VEGFR-1, especially its soluble form (soluble VEGFR-1), is a negative regulator of VEGF availability. We found that breast epithelial cells express soluble VEGFR-1 and hypothesized that because estrogen can regulate expression of members of the VEGF family, it might stimulate angiogenesis in breast cancer by decreasing expression of soluble VEGFR-1. Soluble VEGFR-1 expression decreased in estrogen receptor (ER)-positive but not in ER-negative breast cancer cell lines treated with estrogen. Pretreatment of the cells with the ER antagonist ICI 182,780 blocked the effect. The estrogen-mediated decrease in soluble VEGFR-1 expression was accompanied by a statistically significant increase in angiogenesis in vivo. Our data suggest that inhibition of soluble VEGFR-1 expression represents a novel mechanism--an estrogen-driven angiogenic switch--possibly responsible for breast carcinoma progression.

The combination of suicide gene therapy and radiation enhances the killing of nasopharyngeal carcinoma xenographs

Nasopharyngeal carcinoma (NPC) is very common in Southern China and Southeast Asian countries. To explore a novel and more effective approach to NPC therapy, a combined strategy of suicide genes and radiation was designed in this study. Five suicide gene expression cassettes, yeast CD, yeast CD/UPRT, and yeast CDglyTK gene controlled by CMV, and Egr-1 and a synthetic CMV-enhanced Egr-1 promoter (CE) were constructed in an expression vector p11MS. The expression of suicide genes in NPC CNE-2 cells were detected by RT-PCR and Western blot. The cytotoxicity of suicide gene therapy and radiation were analyzed by MTT assay. An animal study in which yeast CD/UPRT-expressing CNE-2 tumors in nude mice were treated with 5-FC and radiation was also developed. Our results revealed that p11MSCEyCD/UPRT and p11MSCEyCDglyTK are superior over three other constructs in the killing of NPC cells in vitro. We combined suicide gene-expressing tumors, 5-FC treatment, and radiation in vivo and found that the tumors greatly regressed, some disappeared completely in 3 nude mice in the yCD/UPRT group, and a significant difference of tumor volumes was observed between this group and the other four groups (p < 0.05). Our results indicated that suicide gene therapy and radiation have a synergic effect on NPC therapy, and the combined strategy of radiogene therapy is of great potential as a substitute for the traditional method, radiation alone, in NPC therapies.

Characterization and functional analysis of TFPI-2 gene promoter in a human choriocarcinoma cell line

Tissue factor pathway Inhibitor-2 (TFPI-2) is associated with extracellular matrices and plays a major role in cell migration and tumor invasion. In this study, a 4.8-kb human TFPI-2 gene 5'-flanking region was isolated, cloned and sequenced. Promoter region analysis revealed a high GC-rich content without canonical TATA and CAAT boxes but three transcription initiation sites were identified. Moreover, several putative binding sites for transcription factors were identified (MyoD, LYF1, NF-Y, GATA, oct-1, AP-1, Sp1, NF1, NF-kappa B and egr-1). To characterize potential regulatory regions, TFPI-2/luciferase promoter constructs were then transfected in human choriocarcinoma JEG-3 cells. We first showed that the minimal TFPI-2 promoter is located between -166 and -111 from the translation start site. Luciferase activity consistently increased after stimulation of JEG-3 cells by phorbol 12-myristate 13-acetate indicating that NF1, NF-kappa B and egr-1/Sp1 binding sites are crucial in inducible TFPI-2 expression. Moreover, negative regulatory regions included AP-1 binding sites were identified. This study demonstrates that the TFPI-2 gene promoter exhibits typical features of a housekeeping gene.

Reciprocal regulation of expression of the human adenosine 5'-triphosphate binding cassette, sub-family A, transporter 2 (ABCA2) promoter by the early growth response-1 (EGR-1) and Sp-family transcription factors

The human ABCA2 transporter gene encodes a member of a large family of ATP-binding proteins that transport a variety of macromolecules across biological membranes. We have performed luciferase reporter gene assays with promoter constructs comprising the 5'-flanking region to identify cis-regulatory DNA elements and have mapped the minimal promoter region to 321 bp upstream of the translation start site. We have discovered a functional role for two GC-boxes located in the proximal promoter of the ABCA2 gene that contain overlapping sites for the EGR-1 and Sp1 transcription factors. We observed that oligonucleotides containing overlapping EGR-1/Sp1 sites bind the Sp1, Sp3 and Sp4 transcription factors. When BE(2)-M17 cells were treated with phorbol 12-myristate 13-acetate, we observed inducible expression and binding of the EGR-1 transcription factor to the two GC-boxes. Transfection of Sp1, Sp3 or Sp4 expression constructs into Drosophila S2 induced a dose-dependent increase in transcriptional activation of the ABCA2 promoter, but transfection of EGR-1 alone failed to activate transcription. When increasing amounts of EGR-1 were transfected into the BE(2)-M17 neuroblastoma cells we observed a dose-dependent decrease in expression of the ABCA2 promoter, although expression of the endogenous ABCA2 gene increased following transfection of EGR-1.

Stimulation of the murine type II transforming growth factor-beta receptor promoter by the transcription factor Egr-1

Previous studies have demonstrated that differentiation of murine embryonal carcinoma (EC) cells leads to the appearance of high affinity receptors for transforming growth factor-beta (TGF-beta). Subsequently, it was demonstrated that differentiation of F9 EC cells leads to increases in the transcription of the type II TGF-beta-receptor gene (TbetaR-II) and leads to significant increases in the steady-state levels of TbetaR-II mRNA. Analysis of the human TbetaR-II promoter in F9-differentiated cells identified several cis-regulatory elements that influence the activity of the promoter, including a CRE/ATF site and a CCAAT box motif. In the work described in this report, we focused on the effect of the transcription factor Egr-1 on the murine TbetaR-II promoter. We have identified an Egr-1 response-element approximately 150 bp upstream of the major transcription start site of the murine TbetaR-II gene. We demonstrate by electrophoretic mobility shift analysis (EMSA) that this cis-regulatory element binds Egr-1, and we demonstrate that disruption of this site eliminates the response to Egr-1. As part of this analysis, we also examined the effect of Egr-1 on human TbetaR-II promoter. In contrast to a previous report, which reported that Egr-1 inhibits expression of human TbetaR-II promoter/reporter gene constructs, we did not observe an inhibitory effect of Egr-1 that was specific for the human TbetaR-II promoter. Taken together, the findings described in this report identify important differences between the human and the murine TbetaR-II promoter, and our findings identify an Egr-1 cis-regulatory element that is capable of stimulating the activity of the murine TbetaR-II promoter.

The reprogrammed host: Chlamydia trachomatis-induced up-regulation of glycoprotein 130 cytokines, transcription factors, and antiapoptotic genes

OBJECTIVE

Infection with Chlamydia trachomatis is a known cause of sexually transmitted diseases, eye infections (including trachoma), and reactive arthritis (ReA). Because the mechanisms of Chlamydia-induced changes leading to ReA are poorly defined, this study sought to identify the target genes involved at the molecular level.

METHODS

Chlamydia-induced changes in host cells were investigated by combining a screening technique, which utilized complementary DNA arrays on C trachomatis-infected and mock-infected epithelial HeLa cells, with real-time reverse transcription-polymerase chain reaction or enzyme-linked immunosorbent assay of gene products. Some responses were additionally demonstrated on human primary chondrocytes and a human synovial fibroblast cell line, both of which served as model cells for ReA.

RESULTS

Eighteen genes (of 1,176) were found to be up-regulated after 24 hours of infection with this obligate intracellular bacterium, among them the glycoprotein 130 family members IL-11 and LIF, the chemokine gene MIP2-alpha, the transcription factor genes EGR1, ETR101, FRA1, and c-jun, the apoptosis-related genes IEX-1L and MCL-1, adhesion molecule genes such as ICAM1, and various other functionally important genes. In the context of this rheumatic disease, the cytokines and transcription factors seem to be especially involved, since various connections to chondrocytes, synoviocytes, bone remodeling, joint pathology, and other rheumatic diseases have been demonstrated.

CONCLUSION

Infection with C trachomatis seems to reprogram the host cells (independent of activation by lipopolysaccharide or other ultraviolet-resistant bacterial components) at various key positions that act as intra- or intercellular switches, suggesting that these changes and similar Chlamydia-induced functional alterations constitute an important basis of the pathogenic inflammatory potential of these cells in ReA. Our results suggest that this approach is generally useful for the broad analysis of host-pathogen interactions involving obligate intracellular bacteria, and for the identification of target genes for therapeutic intervention in this rheumatic disease.

Elevated Egr-1 in human atherosclerotic cells transcriptionally represses the transforming growth factor-beta type II receptor

Atherosclerotic lesions may progress due to a "failure to die" by vascular repair cells. Egr-1, a zinc finger transcription factor, is elevated more than 5-fold in human carotid lesions relative to the adjacent tunica media. Lesion cells in vitro also express 2-3-fold higher Egr-1 mRNA and protein levels but express much lower levels of the transforming growth factor-beta (TGF-beta) Type II receptor (TbetaR-2) and are functionally resistant to the antiproliferative effects of TGF-beta. Lesion cells fail to express a TbetaR-2 promoter/chloramphenicol acetyltransferase (CAT) construct but overexpress an Egr-1-inducible platelet-derived growth factor-A promoter/CAT construct. Transfection of Egr-1 cDNA represses TbetaR-2/CAT constructs but induces PDGF-A/CAT. Egr-1 transfection reduces the levels of TbetaR-2 and confers resistance to the antiproliferative effect of TGF-beta1. Egr-1 can interact directly with both the -143 Sp1 site and the positive regulatory element 2 (PRE2) (ERT/ets) region of the TbetaR-2 promoter. Thus, although activating a family of stress-responsive genes, Egr-1 also transcriptionally represses one of the major inhibitory pathways that restrains vascular repair.