Decidual lymphatic endothelial cell-derived granulocyte-macrophage colony-stimulating factor induces M1 macrophage polarization via the NF-κB pathway in severe pre-eclampsia

PROBLEM

Direct interactions between macrophages and lymphatic vessels have been shown previously. In pre-eclampsia (PE), macrophages are dominantly polarized into a proinflammatory M1 phenotype and lymphangiogenesis is defective in the decidua. Here, we investigated whether decidual lymphatic endothelial cells (dLECs) affect macrophage polarization in PE.

METHOD OF STUDY

THP-1 macrophages were cocultured with dLECs or cultured in the conditioned medium (CM) of dLECs. Macrophage polarization was measured using flow cytometry. Granulocyte-macrophage colony-stimulating factor (GM-CSF) expression in dLECs was measured using qRT-PCR and ELISA. The activation of nuclear translocation of nuclear factor-κ (NF-κB), an upstream signaling molecule of GM-CSF, was assessed by immunocytochemical localization of p65. Through GM-CSF knockdown and NF-κB inhibition in dLEC, we evaluated whether the GM-CSF/NF-κB pathway of PE dLEC affects decidual macrophage polarization.

RESULTS

The ratio of inflammatory M1 macrophages with HLA-DR⁺ /CD80⁺ markers significantly increased following coculturing with PE dLECs or culturing in PE dLEC CM, indicating that the PE dLEC-derived soluble factor acts in a paracrine manner. GM-CSF expression was significantly upregulated in PE dLECs. Recombinant human GM-CSF induced macrophage polarization toward an M1-like phenotype, whereas its knockdown in PE dLECs suppressed it, suggesting PE dLECs induce M1 macrophage polarization by secreting GM-CSF. The NF-κB p65 significantly increased in PE dLECs compared to the control, and pretreatment with an NF-κB inhibitor significantly suppressed GM-CSF production from PE dLECs.

CONCLUSIONS

In PE, dLECs expressing high levels of GM-CSF via the NF-κB-dependent pathway play a role in inducing decidual M1 macrophage polarization.

Vorinostat-induced acetylation of RUNX3 reshapes transcriptional profile through long-range enhancer-promoter interactions in natural killer cells

Natural killer (NK) cells are an essential part of the innate immune system that helps control infections and tumors. Recent studies have shown that Vorinostat, a histone deacetylase (HDAC) inhibitor, can cause significant changes in gene expression and signaling pathways in NK cells. Since gene expression in eukaryotic cells is closely linked to the complex three-dimensional (3D) chromatin architecture, an integrative analysis of the transcriptome, histone profiling, chromatin accessibility, and 3D genome organization is needed to gain a more comprehensive understanding of how Vorinostat impacts transcription regulation of NK cells from a chromatin-based perspective. The results demonstrate that Vorinostat treatment reprograms the enhancer landscapes of the human NK-92 NK cell line while overall 3D genome organization remains largely stable. Moreover, we identified that the Vorinostat-induced RUNX3 acetylation is linked to the increased enhancer activity, leading to elevated expression of immune response-related genes via long-range enhancerpromoter chromatin interactions. In summary, these findings have important implications in the development of new therapies for cancer and immune-related diseases by shedding light on the mechanisms underlying Vorinostat's impact on transcriptional regulation in NK cells within the context of 3D enhancer network. [BMB Reports 2023; 56(7): 398-403].

Human induced pluripotent stem cell line YCMi007-A generated from a dilated cardiomyopathy patient with a heterozygous dominant c.613C > T (p. Arg205Trp) variant of the TNNT2 gene

Cardiac muscle troponin T protein binds to tropomyosin and regulates the calcium-dependent actin-myosin interaction on thin filaments in cardiomyocytes. Recent genetic studies have revealed that TNNT2 mutations are strongly linked to dilated cardiomyopathy (DCM). In this study, we generated YCMi007-A, a human induced pluripotent stem cell (hiPSC) line from a DCM patient with a p. Arg205Trp mutation in the TNNT2 gene. The YCMi007-A cells show high expression of pluripotent markers, normal karyotype, and differentiation into three germ layers. Thus, YCMi007-A-an established iPSC-could be useful for the investigation of DCM.

An induced pluripotent stem cell line (YCMi006-A) generated from a patient with hypertrophic cardiomyopathy who carries the ACTA1 mutation p.Ile343Met

Hypertrophic cardiomyopathy (HCM) is a common inherited cardiovascular disease and is characterized by hypertrophy of the left ventricle. We reprogrammed peripheral blood mononuclear cells (PBMCs) from a HCM patient into pluripotent stem cells (iPSC) (YCMi006-A) carrying a heterozygous c.1029C > G mutation in ACTA1. The YCMi006-A cells expressed high levels of pluripotent markers, had a normal 46XX karyotype and demonstrated the capacity to differentiate into derivatives of all three germ layers. This cell line can be a valuable tool for investigating the pathogenesis of HCM.

CTCF-mediated chromatin looping provides a topological framework for the formation of phase-separated transcriptional condensates

CTCF is crucial to the organization of mammalian genomes into loop structures. According to recent studies, the transcription apparatus is compartmentalized and concentrated at super-enhancers to form phase-separated condensates and drive the expression of cell-identity genes. However, it remains unclear whether and how transcriptional condensates are coupled to higher-order chromatin organization. Here, we show that CTCF is essential for RNA polymerase II (Pol II)-mediated chromatin interactions, which occur as hyperconnected spatial clusters at super-enhancers. We also demonstrate that CTCF clustering, unlike Pol II clustering, is independent of liquid-liquid phase-separation and resistant to perturbation of transcription. Interestingly, clusters of Pol II, BRD4, and MED1 were found to dissolve upon CTCF depletion, but were reinstated upon restoration of CTCF, suggesting a potent instructive function for CTCF in the formation of transcriptional condensates. Overall, we provide evidence suggesting that CTCF-mediated chromatin looping acts as an architectural prerequisite for the assembly of phase-separated transcriptional condensates.

Liver-Specific Deletion of Mouse CTCF Leads to Hepatic Steatosis via Augmented PPARγ Signaling

BACKGROUND & AIMS

The liver is the major organ for metabolizing lipids, and malfunction of the liver leads to various diseases. Nonalcoholic fatty liver disease is rapidly becoming a major health concern worldwide and is characterized by abnormal retention of excess lipids in the liver. CCCTC-binding factor (CTCF) is a highly conserved zinc finger protein that regulates higher-order chromatin organization and is involved in various gene regulation processes. Here, we sought to determine the physiological role of CTCF in hepatic lipid metabolism.

METHODS

We generated liver-specific, CTCF-ablated and/or CD36 whole-body knockout mice. Overexpression or knockdown of peroxisome proliferator-activated receptor (PPAR)γ in the liver was achieved using adenovirus. Mice were examined for development of hepatic steatosis and inflammation. RNA sequencing was performed to identify genes affected by CTCF depletion. Genome-wide occupancy of H3K27 acetylation, PPARγ, and CTCF were analyzed by chromatin immunoprecipitation sequencing. Genome-wide chromatin interactions were analyzed by in situ Hi-C.

RESULTS

Liver-specific, CTCF-deficient mice developed hepatic steatosis and inflammation when fed a standard chow diet. Global analysis of the transcriptome and enhancer landscape revealed that CTCF-depleted liver showed enhanced accumulation of PPARγ in the nucleus, which leads to increased expression of its downstream target genes, including fat storage-related gene CD36, which is involved in the lipid metabolic process. Hepatic steatosis developed in liver-specific, CTCF-deficient mice was ameliorated by repression of PPARγ via pharmacologic blockade or adenovirus-mediated knockdown, but hardly rescued by additional knockout of CD36.

CONCLUSIONS

Our data indicate that liver-specific deletion of CTCF leads to hepatosteatosis through augmented PPARγ DNA-binding activity, which up-regulates its downstream target genes associated with the lipid metabolic process.

p53 expression confers sensitivity to 5-fluorouracil via distinct chromatin accessibility dynamics in human colorectal cancer

One of the most commonly used drugs in chemotherapy, 5-fluorouracil (5-FU) has been shown to be effective in only 10-15% of patients with colon cancer. Thus, studies of the mechanisms affecting 5-FU sensitivity in these patients are necessary. The tumor suppressor protein p53 is a transcription factor that serves important roles in cell apoptosis by regulating the cell cycle. It has also been characterized as a key factor influencing drug sensitivity. Furthermore, accessible chromatin is a hallmark of active DNA regulatory elements and functions as a crucial epigenetic factor regulating cancer mechanisms. The present study assessed the genetic regulatory landscape in colon cancer by performing RNA sequencing and Assay for Transposase-Accessible Chromatin sequencing, and investigated the effects of 5-FU on chromatin accessibility and gene expression. Notably, while treatment with 5-FU mediated global increases in chromatin accessibility, chromatin organization in several genomic regions differed depending on the expression status of p53. Since the occupancy of p53 does not overlap with accessible chromatin regions, the 5-FU-mediated changes in chromatin accessibility were not regulated by direct binding of p53. In the p53-expressing condition, the 5-FU-mediated accessible chromatin region was primarily associated with genes encoding cell death pathways. Additionally, 5-FU was revealed to induce open chromatin conformation at regions containing binding motifs for AP-1 family transcription factors, which may drive expression of apoptosis pathway genes. In conclusion, expression of p53 may confer 5-FU sensitivity by regulating chromatin accessibility of distinct genes associated with cell apoptosis in a transcription-independent manner.

Depletion of CTCF induces craniofacial malformations in mouse embryos

Increasing evidence implicates chromatin structure and epigenetic regulation in various human developmental disorders, including facial abnormalities and intellectual disability. Mutations in CCCTC-binding factor (CTCF) demonstrate its role in craniofacial development, but early lethality precludes the use of Ctcf mutant mice for phenotypic investigations. In this study, we deleted Ctcf specifically in neural crest cells, the multipotent cells that give rise to many structures of the skeleton and connective tissues in the developing head. Although the pharyngeal arches were initially morphologically normal, many of the neural crest cell-derived skeletal and non-skeletal components were truncated in the Wnt1-Cre; Ctcf^fl/fl mutant mice. The expression level of chondrogenic and osteogenic-related genes were significantly decreased. Our results implicate CTCF in two distinct events in craniofacial development; first, in the regulation of outgrowth and morphogenesis by cell survival and proliferation, and second, in the differentiation of the facial skeleton. Our findings highlight the important contribution of CTCF to craniofacial pathologies.

CCCTC-binding factor regulates the development and function of dendritic cells

Dendritic cells (DCs) are professional antigen presenting cells, which present antigen to cognate T cells. DC activation through diverse toll-like receptors is prerequisite for triggering efficient immune responses to foreign antigens. CCCTC-binding factor (CTCF) is a DNA binding protein that regulates 3D genome structure which is believed to be important to control of gene expression. Here we described that CTCF is required for development and function in DCs. CTCF is critically required for the FLT3L-dependent CD11c+ DCs (FL-DCs) development, unlike for those in the GM-CSF-dependent CD11c+ DC (GM-DCs) development. However, the resultant CTCF-deficient DC number was decreased by 50% in both FLT3L- and GM-CSF-supplemented culture conditions. Although CTCF was required for bone marrow (BM) progenitor proliferation in both FLT3L-and GM-CSF-supplemented cultures, CTCF-deficient GM-DCs showed normal cellular apoptosis rate and higher CD11c+ DC differentiation. Upon TLR4 ligation, CTCF-deficient DCs showed higher expression levels of surface MHCII and co-stimulatory molecules compared to those WT DCs. Thus, our data indicate that CTCF plays a critical role in the overall differentiation, survival, and maturation of DCs.

CTCF deficiency causes expansion of the sensory domain in the mouse cochlea

The cochlea in the mammalian inner ear is a sensitive and sharply organized sound-detecting structure. The proper specification of neurosensory-competent domain in the otic epithelium is required for the formation of mature neuronal and sensory domains. Genetic studies have provided many insights into inner ear development, but there have been few epigenetic studies of inner ear development. CTCF is an epigenetic factor that plays a pivotal role in the organization of global chromatin conformation. To determine the role of CTCF in the otic sensory formation, we made a conditional knockout of Ctcf in the developing otic epithelium by crossing Ctcf^fl/fl mice with Pax2-Cre mice. Ctcf deficiency resulted in extra rows of auditory hair cells in the shortened cochlea on mouse embryonic day 14.5 (E14.5) and E17.5. The massive and ectopic expression of sensory specifiers such as Jag1 and Sox2 indicated that the sensory domain was expanded in the Ctcf-deficient cochlea. Other regulators of the sensory domain such as Bmp4, Gata3, and Fgf10 were not affected. These results suggest that CTCF plays a role in the regulation of the sensory domain in mammalian cochlear development.

CTCF is required for maintenance of auditory hair cells and hearing function in the mouse cochlea

Auditory hair cells play an essential role in hearing. These cells convert sound waves, mechanical stimuli, into electrical signals that are conveyed to the brain via spiral ganglion neurons. The hair cells are located in the organ of Corti within the cochlea. They assemble in a special arrangement with three rows of outer hair cells and one row of inner hair cells. The proper differentiation and preservation of auditory hair cells are essential for acquiring and maintaining hearing function, respectively. Many genetic regulatory mechanisms underlying hair-cell differentiation and maintenance have been elucidated to date. However, the role of epigenetic regulation in hair-cell differentiation and maintenance has not been definitively demonstrated. CTCF is an essential epigenetic component that plays a primary role in the organization of global chromatin architecture. To determine the role of CTCF in mammalian hair cells, we specifically deleted Ctcf in developing hair cells by crossing Ctcf^fl/fl mice with Gfi1^Cre/+ mice. Gfi1^Cre; Ctcf^fl/fl mice did not exhibit obvious developmental defects in hair cells until postnatal day 8. However, at 3 weeks, the Ctcf deficiency caused intermittent degeneration of the stereociliary bundles of outer hair cells, resulting in profound hearing impairment. At 5 weeks, most hair cells were degenerated in Gfi1^Cre; Ctcf^fl/fl mice, and defects in other structures of the organ of Corti, such as the tunnel of Corti and Nuel's space, became apparent. These results suggest that CTCF plays an essential role in maintaining hair cells and hearing function in mammalian cochlea.

CTCF Regulates Otic Neurogenesis via Histone Modification in the Neurog1 Locus

The inner ear is a complex sensory organ responsible for hearing and balance. Formation of the inner ear is dependent on tight regulation of spatial and temporal expression of genes that direct a series of developmental processes. Recently, epigenetic regulation has emerged as a crucial regulator of the development of various organs. However, what roles higher-order chromatin organization and its regulator molecules play in inner ear development are unclear. CCCTC-binding factor (CTCF) is a highly conserved 11-zinc finger protein that regulates the three-dimensional architecture of chromatin, and is involved in various gene regulation processes. To delineate the role of CTCF in inner ear development, the present study investigated inner ear-specific Ctcf knockout mouse embryos (Pax2-Cre; Ctcffl/fl ). The loss of Ctcf resulted in multiple defects of inner ear development and severely compromised otic neurogenesis, which was partly due to a loss of Neurog1 expression. Furthermore, reduced Neurog1 gene expression by CTCF knockdown was found to be associated with changes in histone modification at the gene's promoter, as well as its upstream enhancer. The results of the present study demonstrate that CTCF plays an essential role in otic neurogenesis by modulating histone modification in the Neurog1 locus.

Effects of the Th2-dominant milieu on allergic responses in Der f 1-activated mouse basophils and mast cells

Although basophils and mast cells share similar phenotypic and functional properties, little is known about the difference in the initial Th2 immune responses of these cells following exposure to proteolytic allergens. Here, we investigated the mechanisms of Th2-mediated immune responses in mouse bone marrow-derived basophils (BMBs) and mast cells (BMMCs) via stimulation with the cysteine protease allergen Der f 1. Our results showed that Th2 cytokines were induced from BMBs by active recombinant Der f 1 (rDer f 1 independently with Toll-like receptor (TLR) 2 and TLR4. Although both BMBs and BMMCs expressed protease-activated receptors on their surfaces, PAR expression following exposure to rDer f 1 was altered only in basophils. G protein-coupled receptors in basophils were found to be associated with interleukin (IL)-4 and IL-13 production from BMBs upon Der f 1 treatment. Secretion of Th2 cytokines from rDer f 1-treated basophils was mediated by G protein βγ and phosphatidylinositol 3-kinase γ through the extracellular signal-regulated kinase and c-Jun N-terminal kinase pathways. These findings provide insights into the roles of cysteine proteases in Th2 immune responses, such as allergic diseases, and improve our understanding of the mechanisms of Th2 cytokine production.

Tumor Necrosis Factor-producing T-regulatory Cells Are Associated With Severe Liver Injury in Patients With Acute Hepatitis A

BACKGROUND AND AIMS

CD4⁺CD25⁺Foxp3⁺ T-regulatory (Treg) cells control immune responses and maintain immune homeostasis. However, under inflammatory conditions, Treg cells produce cytokines that promote inflammation. We investigated production of tumor necrosis factor (TNF) by Treg cells in patients with acute hepatitis A (AHA), and examined the characteristics of these cells and association with clinical factors.

METHODS

We analyzed blood samples collected from 63 patients with AHA at the time of hospitalization (and some at later time points) and 19 healthy donors in South Korea. Liver tissues were collected from patients with fulminant AHA during liver transplantation. Peripheral blood mononuclear cells were isolated from whole blood and lymphocytes were isolated from liver tissues and analyzed by flow cytometry. Cytokine production from Treg cells (CD4⁺CD25⁺Foxp3⁺) was measured by immunofluorescence levels following stimulation with anti-CD3 and anti-CD28. Epigenetic stability of Treg cells was determined based on DNA methylation patterns. Phenotypes of Treg cells were analyzed by flow cytometry and an RORγt inhibitor, ML-209, was used to inhibit TNF production. Treg cell suppression assay was performed by co-culture of Treg-depleted peripheral blood mononuclear cells s and isolated Treg cells.

RESULTS

A higher proportion of CD4⁺CD25⁺Foxp3⁺ Treg cells from patients with AHA compared with controls produced TNF upon stimulation with anti-CD3 and anti-CD28 (11.2% vs 2.8%). DNA methylation analysis confirmed the identity of the Treg cells. TNF-producing Treg cells had features of T-helper 17 cells, including up-regulation of RORγt, which was required for TNF production. The Treg cells had reduced suppressive functions compared with Treg cells from controls. The frequency of TNF-producing Treg cells in AHA patients' blood correlated with their serum level of alanine aminotransferase.

CONCLUSIONS

Treg cells from patients with AHA have altered functions compared with Treg cells from healthy individuals. Treg cells from patients with AHA produce higher levels of TNF, gain features of T-helper 17 cells, and have reduced suppressive activity. The presence of these cells is associated with severe liver injury in patients with AHA.

Skin-Specific CD301b+ Dermal Dendritic Cells Drive IL-17-Mediated Psoriasis-Like Immune Response in Mice

Conventional dendritic cells (cDCs) are composed of heterogeneous subsets commonly arising from dendritic cell (DC)-committed progenitors. A population of CD301b-expressing DCs has recently been identified in non-lymphoid barrier tissues such as skin. However, whether CD301b⁺ DCs in the skin represent an ontogenetically unique subpopulation of migratory cDCs has not been fully addressed. Here, we demonstrated that CD301b⁺ dermal DCs were distinct subpopulation of FMS-like tyrosine kinase 3 ligand (FLT3L)-dependent CD11b⁺ cDC2 lineage, which required an additional GM-CSF cue for the adequate development. Although the majority of lymphoid-resident cDC2 lacked CD301b expression, dermal migratory cDC2 contained a substantial fraction of CD301b⁺ subset. Similar to CD301b^- population, CD301b⁺ dermal DC development was closely regulated by FLT3 signaling, suggesting their common origin from FLT3L-responsive cDC progenitors. However, FLT3L-driven cDC progenitor culture was not sufficient, but additional GM-CSF treatment was required to produce CD301b⁺ cDC2. In vivo development of CD301b⁺ cDC2 was significantly augmented by exogenous GM-CSF, while the repopulation of CD301b⁺ dermal cDC2 was abrogated by GM-CSF neutralization. Functionally, CD301b⁺ cDC2 was capable of producing a high level of IL-23, and the depletion of CD301b⁺ cDC2 effectively prevented IL-17-mediated psoriasiform dermatitis. Therefore, our findings highlight the differentiation program of a distinct CD301b⁺ dermal cDC2 subset in the skin and its involvement in psoriatic inflammation.

CCCTC-binding factor is essential to the maintenance and quiescence of hematopoietic stem cells in mice

Hematopoiesis involves a series of lineage differentiation programs initiated in hematopoietic stem cells (HSCs) found in bone marrow (BM). To ensure lifelong hematopoiesis, various molecular mechanisms are needed to maintain the HSC pool. CCCTC-binding factor (CTCF) is a DNA-binding, zinc-finger protein that regulates the expression of its target gene by organizing higher order chromatin structures. Currently, the role of CTCF in controlling HSC homeostasis is unknown. Using a tamoxifen-inducible CTCF conditional knockout mouse system, we aimed to determine whether CTCF regulates the homeostatic maintenance of HSCs. In adult mice, acute systemic CTCF ablation led to severe BM failure and the rapid shrinkage of multiple c-Kit^hi progenitor populations, including Sca-1⁺ HSCs. Similarly, hematopoietic system-confined CTCF depletion caused an acute loss of HSCs and highly increased mortality. Mixed BM chimeras reconstituted with supporting BM demonstrated that CTCF deficiency-mediated HSC depletion has both cell-extrinsic and cell-intrinsic effects. Although c-Kit^hi myeloid progenitor cell populations were severely reduced after ablating Ctcf, c-Kit^int common lymphoid progenitors and their progenies were less affected by the lack of CTCF. Whole-transcriptome microarray and cell cycle analyses indicated that CTCF deficiency results in the enhanced expression of the cell cycle-promoting program, and that CTCF-depleted HSCs express higher levels of reactive oxygen species (ROS). Importantly, in vivo treatment with an antioxidant partially rescued c-Kit^hi cell populations and their quiescence. Altogether, our results suggest that CTCF is indispensable for maintaining adult HSC pools, likely by regulating ROS-dependent HSC quiescence.

Keap1 knockdown in melanocytes induces cell proliferation and survival via HO-1-associated β-catenin signaling

BACKGROUND

Nrf2-Keap1 signaling pathway protects cells against photo-oxidative stress. Yet in recent works, its role in melanogenesis together with cell protection functions against oxidative stress has been gaining interest. However, its effect on melanogenesis still has contradictory results from different studies.

OBJECTIVE

The aims of our study were to investigate the effect of Keap1 silencing in melanocyte on melanogenesis and its associated mechanism.

METHODS

Primary human epidermal melanocytes and melan-a cell line were used for this experiment. RNA sequencing was done to identify genes involved in melanocyte biology using Keap1 knockdown through siRNA techniques. And melanogenesis and the expression of melanogenesis-associated molecules were evaluated in Keap1 silenced melanocyte to examine the effects of Keap1 on melanogenesis, melanocyte growth, and related pathways.

RESULTS

RNA-sequencing data revealed that Keap1 knockdown in primary human epidermal melanocytes (PHEMs) induced cell survival-related gene expression. Additionally, siRNA-mediated inhibition of Keap1 led to upregulation of MITF and melanogenesis-associated molecules along with Nrf2 activation in PHEMs. HO-1, a major gene that is upregulated in RNA-sequencing using Keap1-silenced PHEMs, protected melanocytes against H₂O₂-induced cell death and upregulated MITF and β-catenin expression. Further, increased expression of melanogenesis-associated molecules after Keap1 silencing was validated to occur through HO-1-associated β-catenin activation in a Keap1 and HO-1 double knockdown experiment.

CONCLUSION

This work suggests that Keap1 silencing in melanocytes induced melanogenesis and the expression of melanogenesis-associated molecules through HO-1-associated β-catenin activation. Keap1 downregulation in melanocytes is important for cell proliferation and survival.

Epigenome mapping highlights chromatin-mediated gene regulation in the protozoan parasite Trichomonas vaginalis

Trichomonas vaginalis is an extracellular flagellated protozoan parasite that causes trichomoniasis, one of the most common non-viral sexually transmitted diseases. To survive and to maintain infection, T. vaginalis adapts to a hostile host environment by regulating gene expression. However, the mechanisms of transcriptional regulation are poorly understood for this parasite. Histone modification has a marked effect on chromatin structure and directs the recruitment of transcriptional machinery, thereby regulating essential cellular processes. In this study, we aimed to outline modes of chromatin-mediated gene regulation in T. vaginalis. Inhibition of histone deacetylase (HDAC) alters global transcriptional responses and induces hyperacetylation of histones and hypermethylation of H3K4. Analysis of the genome of T. vaginalis revealed that a number of enzymes regulate histone modification, suggesting that epigenetic mechanisms are important to controlling gene expression in this organism. Additionally, we describe the genome-wide localization of two histone H3 modifications (H3K4me3 and H3K27Ac), which we found to be positively associated with active gene expression in both steady and dynamic transcriptional states. These results provide the first direct evidence that histone modifications play an essential role in transcriptional regulation of T. vaginalis, and may help guide future epigenetic research into therapeutic intervention strategies against this parasite.

Epigenetic regulation of long noncoding RNA UCA1 by SATB1 in breast cancer

Special AT-rich sequence binding protein 1 (SATB1) is a nuclear matrix-associated DNA-binding protein that functions as a chromatin organizer. SATB1 is highly expressed in aggressive breast cancer cells and promotes growth and metastasis by reprograming gene expression. Through genomewide cross-examination of gene expression and histone methylation, we identified SATB1 target genes for which expression is associated with altered epigenetic marks. Among the identified genes, long noncoding RNA urothelial carcinoma-associated 1 (UCA1) was upregulated by SATB1 depletion. Upregulation of UCA1 coincided with increased H3K4 trimethylation (H3K4me3) levels and decreased H3K27 trimethylation (H3K27me3) levels. Our study showed that SATB1 binds to the upstream region of UCA1 in vivo, and that its promoter activity increases with SATB1 depletion. Furthermore, simultaneous depletion of SATB1 and UCA1 potentiated suppression of tumor growth and cell survival. Thus, SATB1 repressed the expression of oncogenic UCA1, suppressing growth and survival of breast cancer cells. [BMB Reports 2016; 49(10): 578-583].

Dynamic Long-Range Chromatin Interaction Controls Expression of IL-21 in CD4+ T Cells

IL-21, a pleiotropic cytokine strongly linked with autoimmunity and inflammation, regulates diverse immune responses. IL-21 can be potently induced in CD4(+) T cells by IL-6; however, very little is known about the mechanisms underlying the transcriptional regulation of the Il21 gene at the chromatin level. In this study, we demonstrated that a conserved noncoding sequence located 49 kb upstream of the Il21 gene contains an enhancer element that can upregulate Il21 gene expression in a STAT3- and NFAT-dependent manner. Additionally, we identified enhancer-blocking insulator elements in the Il21 locus, which constitutively bind CTCF and cohesin. In naive CD4(+) T cells, these upstream and downstream CTCF binding sites interact with each other to make a DNA loop; however, the Il21 promoter does not interact with any cis-elements in the Il21 locus. In contrast, stimulation of CD4(+) T cells with IL-6 leads to recruitment of STAT3 to the promoter and novel distal enhancer region. This induces dynamic changes in chromatin configuration, bringing the promoter and the regulatory elements in close spatial proximity. The long-range interaction between the promoter and distal enhancer region was dependent on IL-6/STAT3 signaling pathway but was disrupted in regulatory T cells, where IL-21 expression was repressed. Thus, our work uncovers a novel topological chromatin framework underlying proper transcriptional regulation of the Il21 gene.

Programmed cell death-ligand 1 ameliorates psoriatic inflammation by inhibiting TCR-induced IL-17A production of T cells overexpressing PD-1

Psoriasis is one of the most common chronic inflammatory diseases in the skin. Recently, IL-17-producing T cells have been shown to play a critical role in psoriatic inflammation. Programmed cell death-1 (PD-1) is a co-inhibitory receptor expressed on T cells in various chronic inflammatory diseases; however, it remains to be elucidated whether PD-1 is overexpressed on T cells in psoriasis and whether PD-1 agonist alleviates psoriatic inflammation. We examined PD-1 expression on IL-17A-producing T cells from Imiquimod (IMQ)-treated mice and psoriasis patients. Additionally, we investigated the therapeutic effect of recombinant programmed cell death ligand-1-Fc (PD-L1-Fc) protein on IMQ-induced psoriatic inflammation. During IMQ-induced psoriatic inflammation, PD-1 is overexpressed on CD27−Vγ1− γδ T cells. Further, PD-1 expression on IL-17A+ T cells was confirmed in tissue samples from patients with psoriatic skin. In the CD27−Vγ1−γδ T cell population, Vγ4−γδ T cells with Vγ6 mRNA expression showed a high level of PD-1 expression. Further, these PD-1hiVγ4−(Vγ6+) γδ T cells were specialized for T-cell receptor (TCR)-induced IL-17A production, which was inhibited by PD-L1-Fc protein treatment. In IMQ-treated mice, PD-L1-Fc protein reduced psoriatic inflammation when given alone and enhanced the therapeutic effect of anti-p40 when given in combination. In conclusion, PD-1 is overexpressed in IL-17A-producing T cells in both IMQ-treated mice and psoriasis patients, and recombinant PD-L1-Fc protein alleviates psoriatic inflammation in IMQ-treated mice.

Programmed cell death ligand 1 alleviates psoriatic inflammation by suppressing IL-17A production from programmed cell death 1-high T cells

BACKGROUND

Psoriasis is one of the most common chronic inflammatory diseases of the skin. Recently, IL-17-producing T cells have been shown to play a critical role in psoriatic inflammation. Programmed cell death 1 (PD-1) is a coinhibitory receptor expressed on T cells in various chronic inflammatory diseases; however, the expression and function of PD-1 during psoriatic inflammation have not previously been characterized.

OBJECTIVE

We examined PD-1 expression on IL-17A-producing T cells from imiquimod-treated mice and patients with psoriasis. Additionally, we investigated the therapeutic effect of recombinant programmed cell death ligand 1 (PD-L1) protein on imiquimod-induced psoriatic inflammation.

METHODS

PD-1 expression on IL-17A-producing γδ T cells from imiquimod-treated mice was examined by means of multicolor flow cytometric analysis. In the psoriatic skin of patients, PD-1 and IL-17A expression was analyzed by using immunofluorescence. The therapeutic effect of PD-L1-Fc fusion protein (PD-L1-Fc) was assessed in imiquimod-treated mice ex vivo and in vivo.

RESULTS

During imiquimod-induced psoriatic inflammation, PD-1 is overexpressed on CD27(-)Vγ1(-) γδ T cells. Furthermore, PD-1 expression on IL-17A(+) T cells was confirmed in psoriatic skin tissues from patients and imiquimod-treated mice. In the CD27(-)Vγ1(-) γδ T-cell population, Vγ4(-) γδ T cells with Vγ6 mRNA expression showed a high level of PD-1 expression. Furthermore, these PD-1(hi)Vγ4(-) (Vγ6(+)) γδ T cells were specialized for anti-CD3-induced IL-17A production, which was inhibited by PD-L1-Fc treatment. In imiquimod-treated mice PD-L1-Fc reduced psoriatic inflammation when given alone and enhanced the therapeutic effect of anti-p40 when given in combination.

CONCLUSION

PD-1 is overexpressed in IL-17A-producing T cells in both imiquimod-treated mice and patients with psoriasis. Moreover, recombinant PD-L1-Fc alleviates psoriatic inflammation in imiquimod-treated mice.

Abstract A28: NFATC3-PLA2G15 fusion transcript identified by RNA-sequencing promotes tumor progression in colorectal cancer cells

In order to identify novel fusion transcripts in colorectal cancer, we carried out paired-end RNA sequencing in 28 human colorectal cancer cell lines. Fusion transcript candidates were identified using ChimeraScan and FusionMap tools. We obtained 1380 candidates having 4 or more read counts and spanning reads. Among the candidates, we selected 27 candidates for validation which harbors genes related to the Wnt signaling pathway or kinases according to KEGG or DAVID. After the targeted gene filtering step, validation using RT-PCR with fusion specific primers finally resulted in 2 intra- and 1 inter-fusion transcripts. Intra-fusion transcripts were NFATC3-PLA2G15 and AKAP13-PDE8A and inter-fusion transcript was KRT8-PKM2 each identified in colo-320, SW-480 and SNU-1235, respectively. The fusion junctions were confirmed by Sanger sequencing. NFATC3-PLA2G15 fusion transcripts consisted of exon 1-9 of NFATC3 (nuclear factor of activated T-cells, cytoplasmic 3) gene and exon 2-6 of the PLA2G15 (Phospholipase A2, Group 5) gene and both located on the same chromosome 16q. NFATC3 is known as transcription factor in the Wnt signaling pathway and regulates function of the target genes like cell proliferation, invasion and epithelial-to-mesenchymal transition (EMT). Under the experiments using siRNA in the colo-320 cell carrying fusion transcript, knockdown of the NFATC3-PLA2G15 fusion transcript decreased mRNA and protein expression of mesenchymal markers, namely vimentin (VIM), Twist-related protein 1 (TWIST1) and fibronectin (FN), and increased epithelial markers, E-cadherin (CDH1) and claudin-1 (CLDN1). Fusion transcripts knockdown also led to decrease of the invasion ability regulated by above markers. Moreover, soft agar assay showed inhibition of colony formation after fusion transcript knockdown. Fusion transcript downregulation also resulted in decrease of cell proliferation and mRNA and protein expression of cyclin D but increase in p27 level. The knockdown did not have influence in the fusion negative cell line. Collectively, these results suggest that the NFATC3-PLA2G15 fusion transcript is involved in invasion and proliferation of colorectal cancer cells.

Citation Format: JE Jang, HP Kim, SH Lee, DW Lee, YJ Lim, SW Han, TY Kim. NFATC3-PLA2G15 fusion transcript identified by RNA-sequencing promotes tumor progression in colorectal cancer cells. [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2015 Nov 5-9; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2015;14(12 Suppl 2):Abstract nr A28.

Modulation of dendritic cell function by Trichomonas vaginalis-derived secretory products

Trichomoniasis caused by the parasitic protozoan Trichomonas vaginalis is the most common sexually transmitted disease in the world. Dendritic cells are antigen presenting cells that initiate immune responses by directing the activation and differentiation of naïve T cells. In this study, we analyzed the effect of Trichomonas vaginalis-derived Secretory Products on the differentiation and function of dendritic cells. Differentiation of bone marrow-derived dendritic cells in the presence of T. vaginalis-derived Secretory Products resulted in inhibition of lipopolysaccharide-induced maturation of dendritic cells, down-regulation of IL-12, and up-regulation of IL-10. The protein components of T. vaginalis-derived Secretory Products were shown to be responsible for altered function of bone marrow-derived dendritic cells. Chromatin immunoprecipitation assay demonstrated that IL-12 expression was regulated at the chromatin level in T. vaginalis-derived Secretory Productstreated dendritic cells. Our results demonstrated that T. vaginalis-derived Secretory Products modulate the maturation and cytokine production of dendritic cells leading to immune tolerance. [BMB Reports 2015; 48(2): 103-108]

Disruption of CTCF/cohesin-mediated high-order chromatin structures by DNA methylation downregulates PTGS2 expression

The CCCTC-binding factor (CTCF)/cohesin complex regulates gene transcription via high-order chromatin organization of the genome. De novo methylation of CpG islands in the promoter region is an epigenetic hallmark of gene silencing in cancer. Although the CTCF/cohesin complex preferentially targets hypomethylated DNA, it remains unclear whether the CTCF/cohesin-mediated high-order chromatin structure is affected by DNA methylation during tumorigenesis. We found that DNA methylation downregulates the expression of prostaglandin-endoperoxide synthase 2 (PTGS2), which is an inducible, rate-limiting enzyme for prostaglandin synthesis, by disrupting CTCF/cohesin-mediated chromatin looping. We show that the CTCF/cohesin complex is enriched near a CpG island associated with PTGS2 and that the PTGS2 locus forms chromatin loops through methylation-sensitive binding of the CTCF/cohesin complex. DNA methylation abolishes the association of the CTCF/cohesin complex with the PTGS2 CpG island. Disruption of chromatin looping by DNA methylation abrogates the enrichment of transcriptional components, such as positive elongation factor b, at the transcriptional start site of the PTGS2 locus. These alterations result in the downregulation of PTGS2. Our results provide evidence that CTCF/cohesin-mediated chromatin looping of the PTGS2 locus is dynamically influenced by the DNA methylation status.

Cross‑reactivity between group-5 and -21 mite allergens from Dermatophagoides farinae, Tyrophagus putrescentiae and Blomia tropicalis

Group-5 and group-21 allergens, produced by house dust mites and storage mites are 36.6-55.8% identical in their sequences and are recognized by at least 50% of immunoglobulin (Ig)E from the sera of individuals allergic to dust mites. In the present study, recombinant group-5 and ‑21 allergens from three mite species, Dermatophagoides farinae (rDer f 5 and 21), Tyrophagus putrescentiae (rTyr p 5 and 21), and Blomia tropicalis (rBlo t 5 and 21), were purified from Escherichia coli, and the IgE reactivities and cross‑reactivities of these allergen variants were assessed. The IgE binding frequencies of rDer f 5, rDer f 21, rTyr p 5, rTyr p 21, rBlo t and rBlo t 21 proteins were 64.95, 65.98, 30.41, 41.24, 30.93 and 21.65%, respectively. The IgE reactivity of rDer f 5 correlated highly with that of rDer f 21 (r=0.733). rTyr p 5 exhibited the highest level of correlation with rTyr p 21 (r=0.950), while the correlation of rBlo t 5 with rBlo t 21 was the lowest observed (r=0.104). The binding of IgE to rDer f 5 and rDer f 21 was not inhibited by any allergens but themselves. While rDer f 5 inhibited only 60.3% of IgE binding to rBlo t 5, rDer f 21 exhibited a high inhibitory effect against rTyr p 5 (93.01%), rTyr p 21 (92.12%), rBlo t 5 (86.97%) and rBlo t 21 (70.30%), implying cross‑reactivity among mite species. The results of the present study demonstrated that the majority of the IgE reactivity to group-5 and -21 storage mite allergens is due to cross‑reaction. It is therefore imperative to develop an accurate, component‑resolved diagnosis for dust mite allergies.

House dust mite allergen Der f 1 induces IL-8 in human basophilic cells via ROS-ERK and p38 signal pathways

Der f 1, a major house dust mite allergen and member of the papain-like cysteine protease family, can provoke immune responses with its proteolytic activity. To understand the role of Der f 1 in inflammatory immune responses, we studied the mechanism of the regulation of interleukin (IL)-8 expressions in human basophilic cell KU812 by proteolytically active recombinant Der f 1. Not only production of IL-8 mRNA was induced but also the DNA binding activity of activator protein-1 (AP-1) and phosphorylation of NF-κB p65 were increased in Der f 1-treated KU812. Furthermore, Der f 1 induction of IL-8 expression was sensitive to pharmacological inhibition of ERK and p38 mitogen activated protein kinase (MAPK) pathways. Der f 1 also activated ERK and p38 MAPK phosphorylation and rapidly induced reactive oxygen species (ROS) production. The antioxidant N-acetyl-cysteine (NAC) inhibited phosphorylation of ERK, but not p38, suggesting that secretion of IL-8 in KU812 cells treated with Der f 1 is dependent on ROS, ERK MAPK and p38 MAPK. We describe the mechanism of Der f 1-induced IL-8 secretion from human basophilic cells, which are thought to be important for allergic inflammation independent of IgE antibodies. These findings improve our understanding of the inflammatory immune response in human basophils to protease allergens.

The pathophysiological role of dendritic cell subsets in psoriasis

Psoriasis is a chronic inflammatory disorder characterized by an erythematous scaly plaque of the skin and is occasionally accompanied by systemic complications. In the psoriatic lesions, an increased number of cytokine-producing dendritic cells and activated T cells are observed, which indicate that psoriasis is a prototype of an immune-mediated dermatosis. During the last decade, emerging studies demonstrate novel roles for the dendritic cell subsets in the process of disease initiation and maintenance of psoriasis. In addition, recently discovered anti-psoriatic therapies, which specifically target inflammatory cytokines produced by lesional dendritic cells, bring much better clinical improvement compared to conventional treatments. These new therapies implicate the crucial importance of dendritic cells in psoriasis pathogenesis. This review will summarize and discuss the dendritic cell subsets of the human skin and their pathophysiological involvement in psoriasis based on mouse- and patient-oriented studies. [BMB Reports 2014; 47(2): 60-68]

Transcription factors Sp1 and Sp3 regulate expression of human ABCG2 gene and chemoresistance phenotype

ABCG2 is a member of the ATP binding cassette (ABC) transmembrane proteins that plays an important role in stem cell biology and drug resistance of cancer cells. In this study, we investigated how expression of human ABCG2 gene is regulated in lung cancer A549 cells. Binding of Sp1 and Sp3 transcription factors to the ABCG2 promoter in vitro and in vivo was elucidated by electrophoretic mobility shift assay and chromatin immunoprecipitation assay. The ABCG2 promoter activity was impaired when Sp1 sites were mutated but was enhanced by overexpression of Sp1 or Sp3 proteins. Knockdown of Sp1 or Sp3 expression by short interfering RNA significantly decreased the expression of ABCG2 mRNA and protein, resulting in attenuated formation of the side population in A549 cells. In addition, Sp1 inhibition in vivo by mithramycin A suppressed the percentage of the side population fraction and sphere forming activities of A549 cells. Moreover, inhibiting Sp1- or Sp3-dependent ABCG2 expression caused chemosensitization to the anticancer drug cisplatin. Collectively, our results demonstrate that Sp1 and Sp3 transcription factors are the primary determinants for activating basal transcription of the ABCG2 gene and play an important role in maintaining the side population phenotype of lung cancer cells.

Transcriptional and epigenetic networks in the development and maturation of dendritic cells

Dendritic cells (DCs) are professional antigen-presenting cells that provide a critical link between the innate and adaptive immune responses. The genetic program required for differentiation of DCs from their hematopoietic precursors is controlled by both cytokines and transcription factors. The signals transduced from cytokines recruit specific transcription factors, enabling the expression of a distinct transcriptome that is required for specification of different DC lineages. The establishment of a distinct transcriptome also depends on chromatin modifications associated with critical cis elements of lineage-specific genes. In this review, recent advances in the understanding of the transcriptional network governing DC lineage specification are summarized, along with current views of the dynamic DC epigenome.

Biological screening of 100 plant extracts for cosmetic use (II): anti-oxidative activity and free radical scavenging activity

Methanol aqueous extracts of 100 plants were screened for anti-oxidative activity using Fenton's reagent/ethyl linoleate system and for free radical scavenging activity using the 1,1-diphenyl-2-picryl hydrazyl free radical generating system. The results suggest that 14 plants - Alpinia officinarum, Areca catechu, Brassica alba, Cannabis sativa, Curcuma longa, Curcuma aromatica, Eugenia caryophyllata, Evodia officinalis, Paeonia suffruticosa, Rhaphanus sativus, Rheum palmatum, Rhus verniciflua, Trapa bispinosa, Zanthoxylum piperitum - may be potential sources of anti-oxidants. Eight plants - Citrus aurantium, Cornus officinalis, Gleditsia japonica, Lindera strychnifolia, Phragmites communis, Prunus mume, Schizandra chinensis, Terminalia chebula - may be the potential source of free radical scavengers from natural plant.

Antihepatotoxic zeaxanthins from the fruits ofLycium chinense

A CHCl(3): MeOH extract of the fruit ofLycium chinense Mill. (Solanaceae) was found to afford significant protection against carbon tetrachloride-induced toxicity in primary cultures of rat hepatocytes. Subsequent activity-guided fractionation resulted in the isolation of zeaxanthin and zeaxanthin dipalmitate as antihepatotoxic components. Incubation of injured hepatocytes with zeaxanthin dipalmitate reduced the levels of glutamic pyruvic transaminase (GPT) and sorbitol dehydrogenase (SDH) released from damaged cells to 60.5% and 76.3% of those released from untreated controls, respectively. Zeaxanthin also reduced the levels of GPT and SDH to 68.5% and 61.3% of the levels of those released from the untreated control. The results confirm the hepatoprotective activities of zeaxanthins. Antihepatotoxic activities of zeaxanthins are comparable to that of silybin.

Biological screening of 100 plant extracts for cosmetic use (I): inhibitory activities of tyrosinase and DOPA auto-oxidation

The aim of this study was to evaluate several plant extracts with a view to developing melanogenesis inhibitors. In this study, 100 plant extracts were screened to elucidate their whitening effects using in vitro inhibition of tyrosinase and DOPA auto-oxidation activity. Several plant extracts such as Chaenomeles speciosa, Dryopteris crassirhizoma, Gastrodia ellata, Glycyrrhiza glabra, Morus alba, Myristica fragrans, Rheum palmatum and Sophora japonica showed inhibition of mushroom tyrosinase activity. Plant extracts including Bupleurum falcatum, Caragana sinica, Morus alba and Tussilago farfara showed inhibition of DOPA auto-oxidation activity.

Inhibition of arachidonate release from rat peritoneal macrophage by biflavonoids

Biflavonoid is one of unique classes of naturally-occurring bioflavonoid. Previously, certain biflavonoids were found to possess the inhibitory effects on phospholipase A(2) activity and lymphocytes proliferation(1) suggesting their anti-inflammatory/immunoregulatory potential. In this study, effects of several biflavonoids on arachidonic acid release from rat peritoneal macrophages were investigated, because arachidonic acid released from the activated macrophages is one of the indices of inflammatory conditions. When resident peritoneal macrophages labeled with [(3)H]arachidonic acid were activated by phorbol 12-myristate 13-acetate (PMA) or calcium ionophore, A23187, radioactivity released in the medium was increased approximately 4.1 approximately 7.3 fold after 120 min incubation compared to the spontaneous release in the control incubation. In this condition, biflavonoids (10 uM) such as ochnaflavone, ginkgetin and isoginkgetin, showed inhibition of arachidonate release from macrophages activated by PMA (32.5 approximately 40.0% inhibition) or A23187 (21.7 approximately 41.7% inhibition). Amentoflavone showed protection only against PMA-induced arachidonate release, while apigenin, a monomer of these biflavonoids, did not show the significant inhibition up to 10 uM. Staurosporin (1 uM), a protein kinase C inhibitor, showed an inhibitory effect only against PMA-induced arachidonate release (96.8% inhibition). Inhibition of arachidonate release from the activated macrophages may contribute to an anti-inflammatory potential of biflavonoidsin vivo.

IL-21 promotes the pathologic immune response to Pneumovirus infection (44.2)

IL-21 is a type I cytokine whose targets include both lymphoid and myeloid populations and whose role in host responses to pulmonary pathogens has not been evaluated. Pneumonia virus of mice (PVM) is a natural rodent pathogen that initiates a respiratory infection in mice that resembles severe human respiratory syncytial virus (RSV) disease. We demonstrate that IL-21 is expressed by CD4+ T cells in the lung following infection of animals with PVM. Examination of PVM-infected Il21r-/- mice revealed much less lung infiltration by neutrophils than was seen in WT mice, and consistent with this, Il21r-/- mice also had reduced levels of the chemokine CXCL1 in both bronchoalveolar lavage fluid and lung parenchyma. Both CD8+ and CD4+ T cells as well as γδ T cells were also reduced in PVM-infected Il21r-/- mice, even though CD8+ T cell cytokine responses were not diminished. Th17 cytokines were expressed at the same levels as in WT mice, but IL-6 production in response to PVM was diminished in Il21r-/- mice. Although virus recovery was similar in WT and Il21r-/- mice, the absence of IL-21 signaling conferred a survival advantage to Il21r-/- mice, indicating that IL-21 can contribute to a detrimental inflammatory state in the lung. Overall, our findings suggest that therapeutic manipulation of IL-21 signaling, such as IL-21 receptor blockade, may represent an immunomodulatory strategy for averting the negative sequelae of this and potentially other respiratory virus infections.

Abstract 2211: Accessible chromatin structure permits factors Sp1 and Sp3 to regulate human TGFBI gene expression

Transforming growth factor beta 1-induced (TGFBI) protein is an extracellular matrix (ECM) protein expressed widely in human tissues. The gene encoding this protein was first described as a major TGF-b-responsive gene in the lung adenocarcinoma cell line A549. TGFBI appears to mediate cell adhesion and migration through interaction with integrin, and increased TGFBI expression has been associated with inflammatory diseases including rheumatoid arthritis, atherosclerosis, cyclosporine nephropathy, and stab wound healing. TGFBI is ubiquitously expressed in healthy tissues, while disrupted TGFBI expression has been described in human tumor cell lines and in human primary tumor samples. A general function of this protein appears to be as a promoter or suppressor of cancer progression, depending on the tissue. Regulation of TGFBI expression by epigenetic mechanism such as DNA methylation and microRNA has been reported, but few studies have focused on how chromatin structure affects transcriptional activity relating to TGFBI expression. We show that both chromatin structure and regulatory elements in the TGFBI promoter region that bind factors Sp1 and Sp3 regulate constitutive expression of TGFBI. In this study, we investigated how human TGFBI expression is regulated in lung and breast cancer cells. We observed that the TGFBI promoter in A549 and MBA-MD-231 cells, which constitutively express TGFBI, existed in an open chromatin conformation associated with transcriptionally permissive histone modifications. Moreover, we found that TGFBI expression required Sp1 transcription elements that can bind transcription factors Sp1 and Sp3 in vitro. Occupancy of the TGFBI promoter by Sp1 and Sp3 in vivo was only observed in TGFBI-expressing cells, indicating that open chromatin conformation might facilitate the binding of Sp1 and Sp3 to the TGFBI promoter region. TGFBI promoter activity was impaired when Sp1 elements were mutated, but was increased when Sp1 or Sp3 factors was overexpressed. Furthermore, Sp1 inhibition in vivo by mithramycin A, as well as knockdown of Sp1 and/or Sp3 expression by short interfering RNA, significantly reduced TGFBI mRNA and protein levels. Thus, our data demonstrated that the expression of TGFBI is well correlated with chromatin conformation at the TGFBI promoter, and that factors Sp1 and Sp3 are the primary determinants for the control of constitutive expression of TGFBI gene.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 2211. doi:1538-7445.AM2012-2211

IL-21 promotes the pathologic immune response to pneumovirus infection

IL-21 is a cytokine with pleiotropic actions, promoting terminal differentiation of B cells, increased Ig production, and the development of Th17 and T follicular helper cells. IL-21 is also implicated in the development of autoimmune disease and has antitumor activity. In this study, we investigated the role of IL-21 in host defense to pneumonia virus of mice (PVM), which initiates an infection in mice resembling that of respiratory syncytial virus disease in humans. We found that PVM-infected mice expressed IL-21 in lung CD4(+) T cells. Following infection, Il21r(-/-) mice exhibited less lung infiltration by neutrophils than did wild-type (WT) mice and correspondingly had lower levels of the chemokine CXCL1 in bronchoalveolar lavage fluid and lung parenchyma. CD8(+), CD4(+), and γδ T cell numbers were also lower in the lungs of PVM-infected Il21r(-/-) mice than in infected WT mice, with normal Th17 cytokines but diminished IL-6 production in PVM-infected Il21r(-/-) mice. Strikingly, Il21r(-/-) mice had enhanced survival following PVM infection, and moreover, treatment of WT mice with soluble IL-21R-Fc fusion protein enhanced their survival. These data reveal that IL-21 promotes the pathogenic inflammatory effect of PVM and indicate that manipulating IL-21 signaling may represent an immunomodulatory strategy for controlling PVM and potentially other respiratory virus infections.

Accessible chromatin structure permits factors Sp1 and Sp3 to regulate human TGFBI gene expression

Transforming growth factor beta 1-induced (TGFBI) protein is an extracellular matrix (ECM) protein that is associated with other ECM proteins and functions as a ligand for various types of integrins. In this study, we investigated how human TGFBI expression is regulated in lung and breast cancer cells. We observed that the TGFBI promoter in A549 and MBA-MD-231 cells, which constitutively express TGFBI, existed in an open chromatin conformation associated with transcriptionally permissive histone modifications. Moreover, we found that TGFBI expression required Sp1 transcription elements that can bind transcription factors Sp1 and Sp3 in vitro. Occupancy of the TGFBI promoter by Sp1 and Sp3 in vivo was only observed in TGFBI-expressing cells, indicating that open chromatin conformation might facilitate the binding of Sp1 and Sp3 to the TGFBI promoter region. TGFBI promoter activity was impaired when Sp1 elements were mutated, but was increased when Sp1 or Sp3 factors was overexpressed. Furthermore, Sp1 inhibition in vivo by mithramycin A, as well as knockdown of Sp1 and/or Sp3 expression by short interfering RNA, significantly reduced TGFBI mRNA and protein levels. Thus, our data demonstrated that the expression of TGFBI is well correlated with chromatin conformation at the TGFBI promoter, and that factors Sp1 and Sp3 are the primary determinants for the control of constitutive expression of TGFBI gene.

DNA methylation-dependent regulation of TrkA, TrkB, and TrkC genes in human hepatocellular carcinoma

The tropomyosin-related kinase (Trk) family of neurotrophin receptors, TrkA, TrkB and TrkC, has been implicated in the growth and survival of human cancers. Here we report that Trks are frequently overexpressed in hepatocellular carcinoma (HCC) from patients and human liver cancer cell lines. To unravel the underlying molecular mechanism(s) for this phenomenon, DNA methylation patterns of CpG islands in TrkA, TrkB, and TrkC genes were examined in normal and cancer cell lines derived from liver. A good correlation was observed between promoter hypermethylation and lower expression of TrkA, TrkB, and TrkC genes, which was supported by the data that inhibiting DNA methylation with 5-azacytidine restored expression of those genes in normal liver cell lines. Furthermore, Trks promoted the proliferation of HepG2 and induced expression of the metastatic regulator, Twist. These results suggest that Trks may contribute to growth and metastasis of liver cancer.

TSLP polymorphisms are associated with asthma in a sex-specific fashion

BACKGROUND

Single nucleotide polymorphisms (SNPs) in thymic stromal lymphopoietin (TSLP) have been associated with IgE (in girls) and asthma (in general). We sought to determine whether TSLP SNPs are associated with asthma in a sex-specific fashion.

METHODS

We conducted regular and sex-stratified analyses of association between SNPs in TSLP and asthma in families of children with asthma in Costa Rica. Significant findings were replicated in whites and African-American participants in the Childhood Asthma Management Program, in African-Americans in the Genomic Research on Asthma in the African Diaspora study, in whites and Hispanics in the Children's Health Study, and in whites in the Framingham Heart Study (FHS).

MAIN RESULTS

Two SNPs in TSLP (rs1837253 and rs2289276) were significantly associated with a reduced risk of asthma in combined analyses of all cohorts (P values of 2 × 10(-5) and 1 × 10(-5) , respectively). In a sex-stratified analysis, the T allele of rs1837253 was significantly associated with a reduced risk of asthma in males only (P = 3 × 10(-6) ). Alternately, the T allele of rs2289276 was significantly associated with a reduced risk of asthma in females only (P = 2 × 10(-4) ). Findings for rs2289276 were consistent in all cohorts except the FHS.

CONCLUSIONS

TSLP variants are associated with asthma in a sex-specific fashion.

Analysis of interleukin-21-induced Prdm1 gene regulation reveals functional cooperation of STAT3 and IRF4 transcription factors

Interleukin-21 (IL-21) is a pleiotropic cytokine that induces expression of transcription factor BLIMP1 (encoded by Prdm1), which regulates plasma cell differentiation and T cell homeostasis. We identified an IL-21 response element downstream of Prdm1 that binds the transcription factors STAT3 and IRF4, which are required for optimal Prdm1 expression. Genome-wide ChIP-Seq mapping of STAT3- and IRF4-binding sites showed that most regions with IL-21-induced STAT3 binding also bound IRF4 in vivo and furthermore revealed that the noncanonical TTCnnnTAA GAS motif critical in Prdm1 was broadly used for STAT3 binding. Comparing genome-wide expression array data to binding sites revealed that most IL-21-regulated genes were associated with combined STAT3-IRF4 sites rather than pure STAT3 sites. Correspondingly, ChIP-Seq analysis of Irf4(-/-) T cells showed greatly diminished STAT3 binding after IL-21 treatment, and Irf4(-/-) mice showed impaired IL-21-induced Tfh cell differentiation in vivo. These results reveal broad cooperative gene regulation by STAT3 and IRF4.

IL-21 mediates suppressive effects via its induction of IL-10

IL-21 is a pleiotropic cytokine that is required for normal Ig production. We previously showed that IL-21 was elevated in BXSB-Yaa mice with systemic lupus erythematosus. These mice also had elevated IL-10 levels, and we now show that IL-21 induces IL-10 mRNA and protein, suggesting unexpected immunosuppressive activities for IL-21. Indeed, Th1 priming with IL-21 leads to accumulation of cells with immunosuppressive activity, and IL-21 overexpression decreases specific Ab production after immunization in an IL-10-dependent fashion. Moreover, we show that IL-21 signaling is required for maximal induction of IL-10 by IL-6 or IL-27. Overall, our data indicate that IL-21 regulates immune responses at least in part by inducing IL-10 and reveal unanticipated immunosuppressive actions for this cytokine.

CREB/ATF-dependent T cell receptor-induced FoxP3 gene expression: a role for DNA methylation

Regulatory T cells (T reg cells) are a population of CD4⁺ T cells that limit immune responses. FoxP3 is a master control transcription factor for development and function of these cells, but its regulation is poorly understood. We have identified a T cell receptor–responsive enhancer in the FoxP3 first intron that is dependent on a cyclic-AMP response element binding protein (CREB)/activating transcription factor (ATF) site overlapping a CpG island. Methylation of this island inversely correlates with CREB binding and FoxP3 expression. Interestingly, transforming growth factor-β, which induces T reg cell formation, decreases methylation of the CpG island and increases FoxP3 expression. Similarly, inhibiting methylation with 5-azacytidine or knocking down the DNA methyltransferase Dnmt1 also induces FoxP3 expression. Conversely, methylation of the CpG island, which decreases CREB binding or expression of dominant-negative CREB, decreases FoxP3 gene expression. Thus, T cell receptor–induced FoxP3 expression in T reg cells is controlled both by sequence-specific binding of CREB/ATF and by DNA methylation of a CpG island.

Interleukin-21 receptor gene induction in human T cells is mediated by T-cell receptor-induced Sp1 activity

Interleukin-21 (IL-21) plays important roles in regulating the immune response. IL-21 receptor (IL-21R) mRNA is expressed at a low level in human resting T cells but is rapidly induced by mitogenic stimulation. We now investigate the basis for IL21R gene regulation in T cells. We found that the -80 to -20 region critically regulates IL-21R promoter activity and corresponds to a major DNase I-hypersensitive site. Electrophoretic mobility shift assays, DNA affinity chromatography followed by mass spectrometry, and chromatin immunoprecipitation assays revealed that Sp1 binds to this region in vitro and in vivo. Moreover, mutation of the Sp1 motif markedly reduced IL-21R promoter activity, and Sp1 small interfering RNAs effectively diminished IL-21R expression in activated T cells. Interestingly, upon T-cell receptor (TCR) stimulation, T cells increased IL-21R expression and Sp1 protein levels while decreasing Sp1 phosphorylation. Moreover, phosphatase inhibitors that increased phosphorylation of Sp1 diminished IL-21R transcription. These data indicate that TCR-induced IL-21R expression is driven by TCR-mediated augmentation of Sp1 protein levels and may partly depend on the dephosphorylation of Sp1.