Change in expression of MGMT during maturation of human monocytes into dendritic cells

Dendritic cells (DCs) maturated from monocytes play an important role in the immune system, not only in defense against conventional infections but also in cancer rejection. Because of the central role of DCs in tumor host defense it is highly important that DCs as well as the progenitor cell population are protected during cancer therapy. Since most anticancer drugs target DNA, the DNA repair capacity is most importance for the response of DCs and their precursor cells. Here, we studied the expression of the DNA repair protein O6-methylguanine-DNA methyltransferase (MGMT) in monocytes obtained from peripheral blood of healthy donors and DCs maturated from monocytes (moDCs). We show that MGMT is expressed at high level in monocytes, comparable to peripheral lymphocytes. The MGMT expression level declines, however, during DC maturation reaching the low level of CD34+ haematopoetic stem cells. Decline of MGMT was observed on activity, protein and RNA level. It is not related to MGMT promoter methylation, suggesting silencing of the MGMT gene in moDCs occurs by other means. Since maturation of monocytes into DCs is provoked by IL-4 and GM-CSF, the data indicate that MGMT is subject to cytokine-mediated regulation. Despite of the high MGMT level, monocytes were more sensitive to methylating agents (MNNG, temozolomide) and equally sensitive to the chloroethylating agent fotemustine than moDCs, undergoing apoptosis upon treatment. The data provide an example that high MGMT expression level does not necessarily implicate a higher level of resistance against O6-alkylating agents.     

Induction of repair enzyme O6-methylguanine-DNA methyltransferase gene expression under the influence of cytokine EMAP II in human cells in vitro

The aim of our study was to investigate the effect of recombinant human cytokine EMAP II (endothelial monocyte-activating polypeptide II) on the expression of MGMT gene, encoding repair enzyme O6-methylguanine-DNA methyltransferase (MGMT) in human cell cultures. The influence of EMAP II on cell proliferation was performed using routine MTT assay. Identification of MGMT in cell extracts was performed using Western blot analysis. We used cell lines: A102 (fibroblasts), CB-1 (umbilical cord blood stromal cells), 4BL6 (cells derived from peripheral blood). It was shown that cytokine EMAP II caused induction of MGMT expression in studied human cell lines. There was a decrease in cell number at high concentrations of this cytokine. It was found that the presence of cytokine EMAP II in serum-free growth medium leads to increasing of repair enzyme MGMT expression level in human cells in vitro.     

Definition of parameters of the condition of oxidizing stress in smooth muscle cells under influence of exogenous nitroso-glutatyon in vitro

Influence of exogenous nitroso-glutatyon on intensity of oxidizing processes in smooth muscles of colon and bronchial tubes in intact and atopic sensitised porpoises (guinea pigs) was studied. In sensitised porpoises, antioxidant protection has been initially reduced against the background of increased maintenance of products of oxidizing that reflects a picture of oxidizing damage and can be associated with an inflammatory process. In incubation with nitroso-glutatyon, a decrease in activities of syperoxiddismutase and catalase is marked and, in sensitised animals, this effect has been expressed to a lesser degree. Syperoxiddismutase and catalase are antioxidant for the enzymes participating in protection of cells from free-radical damage. A dose-dependence decrease in activity catalase and syperoxiddismutase is defined by a parity of the enzymes participating in disintegration of nitrosoglutatyon and the enzymes which have kept antioxidant activity.     

A study of the cloned human erythropoietin gene expression in mammalian cells in vitro

The human gene coding for the principal factor of erythroid cells differentiation, erythropoietin, has been isolated from the genomic phage library using an oligonucleotide probe for the gene. The construction of series of plasmids carrying the erythropoietin gene under the control of various regulatory elements is reported. Efficiency of the erythropoietin gene expression was estimated by testing of the biologically active erythropoietin in conditioned media 48 h after transient transfection of COS 1 and CHO cell lines.     

Recapitulative haematopoietic development of human pluripotent stem cells in the absence of exogenous haematopoietic cytokines

To improve the recapitulative quality of human pluripotent stem cell (hPSC) differentiation, we removed exogenous haematopoietic cytokines from the defined differentiation system. Here, we show that endogenous stimuli and VEGF are sufficient to induce robust hPSC-derived haematopoiesis, intensive generation of haematopoietic progenitors, maturation of blood cells and the emergence of definitive precursor cells including those that phenotypically identical to early human embryonic haematopoietic stem cells (HSCs). Moreover, the cytokine-free system produces significantly higher numbers of haematopoietic progenitors compared to the published protocols. The removal of cytokines revealed a broad developmental potential of the early blood cells, stabilized the hPSC-derived definitive precursors and led to spontaneous activation of inflammatory signalling. Our cytokine-free protocol is simple, efficient, reproducible and applicable for embryonic stem cells (ESCs) and induced PSCs. The spectrum of recapitulative features of the novel protocol makes the cytokine-free differentiation a preferred model for studying the early human haematopoietic development.     

Growth factors and cytokines modulate gene expression of cell-surface proteoglycans in human periodontal ligament cells

Cell-surface proteoglycans have been known to be involved in many functions including interactions with components of the extracellular microenvironment, and act as co-receptors which bind and modify the action of various growth factors and cytokines. The purpose of this study was to determine the regulation by growth factors and cytokines on cell-surface proteoglycan gene expression in cultured human periodontal ligament (PDL) cells. Subconfluent, quiescent PDL cells were treated with various concentrations of serum, bFGF, PDGF-BB, TGF-beta1, IL-beta1, and IFN-gamma. RT-PCR technique was used, complemented with Northern blot for syndecan-1, to examine the effects of these agents on the mRNA expression of five cell-surface proteoglycans (syndecan-1, syndecan-2, syndecan-4, glypican and betaglycan). Syndecan-1 mRNA levels increased in response to serum, bFGF and PDGF-BB, but decreased in response to TGF-beta1, IL-1beta and IFN-gamma. In contrast, syndecan-2 mRNA levels were upregulated by TGF-beta1 and IL-1beta stimulation, but remained unchanged with the other agents. Betaglycan gene expression decreased in response to serum, but was upregulated by TGF-beta1 and unchanged by the other stimulants. Additionally, syndecan-4 and glypican were not significantly altered in response to the regulator molecules studied, with the exception that glypican is decreased in response to IFN-gamma. These data demonstrate that the gene expression of the five cell-surface proteoglycans studied is differentially regulated in PDL cells lending support to the notion of distinct functions for these cell-surface proteoglycans.     

Regulation of gene expression by cytokines and virus in human cells lacking the type-I interferon locus.

A number of genes that are induced by type-I interferons are also activated by one or more other inducers, including double-stranded RNA, viruses, interferon-gamma, interleukin-1 and tumor necrosis factor. However, these inducers can also activate the expression of type-I interferons. Thus, the activation of type-I interferon-inducible genes by these other inducers could be direct, or a secondary consequence of the induction of interferon. To distinguish between these possibilities, we have used cell lines lacking all type-I interferon genes to study the direct effect of potential inducers on the expression of 14 interferon-inducible human genes. We show that double-stranded RNA, virus, interferon-gamma or tumor necrosis factor-alpha can act directly to induce specific subsets of type-I interferon-inducible genes in the absence of any possible type-I interferon involvement. The cis-acting element which confers inducibility by type-I interferon has been shown in some cases to confer inducibility by interferon-gamma, double-stranded RNA or virus as well. However, not all promoters containing such an element respond to both interferon and other inducers. Thus, the ability of a given gene to respond to different inducers most likely depends on the exact nature and specific combination of cis-acting elements present in its promoter.     

The dynamics of gene expression in human lung microvascular endothelial cells after stimulation with inflammatory cytokines

Vascular endothelium plays an essential role in the pathogenesis of vasoocclusion. The changes in the endothelial cell function can be triggered by changes in gene expression caused by interaction with cytokines and blood cells. Using cDNA arrays, we have recently reported complex patterns of gene expression after stimulation of endothelial cells with TNFalpha and IL-1beta. Better understanding of the time course of gene expression changes, their concentration dependence and reversibility after withdrawal of the offending cytokine is essential for successful prevention and therapy of vasoocclusion. Here we present a detailed study of the concentration dependence and time course of gene expression in endothelial cells after their exposure to TNFalpha and IL-1beta. We focus on the adhesion molecules (VCAM-1, ICAM-1, E-selectin) and cytokines (IL-6, GCP-2, MCP-1) that are likely to contribute to vasoocclusion. We report differences in the time course and intensity of their expression and in their response to TNFalpha and IL-1beta stimulation. We demonstrate that expression of the studied genes is upregulated by low TNFalpha concentrations that better reflect the TNFalpha levels detected in the plasma of patients developing vasoocclusion. These results help to understand the changes in the endothelium and to design rational prevention and therapy of vasoocclusion.     

The effect of the colostral cells on gene expression of cytokines in cord blood cells

Beneficial effect of maternal milk is acknowledged, but there is still question whether maternal milk from allergic mother is as good as from healthy one. In our study, we have assayed the effect of cells from colostrum of healthy and allergic mothers on gene expression of cytokines in cord blood cells of newborns of healthy and allergic mothers. Cytokines typical for Th1 (IL-2, IFN-gamma), Th2 (IL-4, IL-13), Tregs (IL-10, TGF-beta), and IL-8 were followed. We were not able to detect significant influence of colostral cells on gene expression of cytokines in cord blood after 2-day coculture using Transwell system. There was no difference in gene expression of cytokines in nonstimulated cord blood cells of newborns of healthy and allergic mothers, but generally increased gene expression of cytokines except IL-10 and TGF-beta after polyclonal stimulation was detected in cord blood cells of children of allergic mothers. There was no difference in IL-10 expression in stimulated cord blood cells of children of healthy and allergic mothers. Gene expression of TGF-beta was even decreased in stimulated cord blood cells of children of allergic mothers in comparison to healthy ones. We have not observed difference in the capacity of colostral cells of healthy and allergic mothers to influence gene expression of cytokines in cord blood cells, but we have described difference in the reactivity of cord blood cells between children of allergic and healthy mothers.     

MicroRNA expression profile of human periodontal ligament cells under the influence of Porphyromonas gingivalis LPS

Periodontitis is a chronic inflammatory disease which is caused by bacterial infection and leads to the destruction of periodontal tissues and resorption of alveolar bone. Thus, special attention should be paid to the mechanism under lipopolysaccharide (LPS)‐induced periodontitis because LPS is the major cause of periodontitis. However, to date, miRNA expression in the LPS‐induced periodontitis has not been well characterized. In this study, we investigated miRNA expression patterns in LPS‐treated periodontal ligament cells (PDLCs). Through miRNA array and differential analysis, 22 up‐regulated miRNAs and 28 down‐regulated miRNAs in LPS‐treated PDLCs were identified. Seven randomly selected up‐regulated (miR‐21‐5p, 498, 548a‐5p) and down‐regulated (miR‐495‐3p, 539‐5p, 34c‐3p and 7a‐2‐3p) miRNAs were examined by qRT‐PCR, and the results proved the accuracy of the miRNA array. Moreover, targets of these deregulated miRNAs were analysed using the miRWalk database. Database for Annotation, Visualization and Integration Discovery software were performed to analyse the Gene Ontology and Kyoto Encyclopaedia of Genes and Genomes pathway of differential expression miRNAs, and the results shown that Toll‐like receptor signalling pathway, cAMP signalling pathway, transforming growth factor‐beta signalling pathway, mitogen‐activated protein kinase (MAPK) signalling pathway and other pathways were involved in the molecular mechanisms underlying LPS‐induced periodontitis. In conclusion, this study provides clues for enhancing our understanding of the mechanisms and roles of miRNAs as key regulators of LPS‐induced periodontitis.     

Ceruloplasmin gene expression in human cancer cells

The copper transport protein, ceruloplasmin, is suggested to have a role in cancer since it is involved in angiogenesis and neovascularization. In order to understand the role of ceruloplasmin in malignant cells, we have recently isolated and sequenced a human ceruloplasmin cDNA clone. In the present study, we have investigated the ceruloplasmin gene expression in human colon and breast cancer cell lines. The poly (A) RNA from human colon (WiDr) and human breast (MCF-7) cancer cell lines was analyzed for the presence of ceruloplasmin mRNA. The Northern blot analysis revealed the presence of a 3.7 kb band of ceruloplasmin mRNA in these cell lines. Dot blot analysis revealed that ceruloplasmin mRNA is at least three fold more abundant in tumor cells as compared to normal rat liver.     

Determine exogenous human DDAH2 gene function in rabbit bone marrow–derived endothelial progenitor cells in vitro

The in vitro amplification of endothelial progenitor cells (EPCs) is an important method because of its role in gene transferring and regenerative medicine. In this study, we isolated rabbit bone marrow–derived EPCs to further manipulation and overexpression of dimethylarginine dimethylaminohydrolase (DDAH) in EPCs. Isolated EPCs were cultured, expanded in endothelial basal medium. Morphology of EPCs and expression levels of surface markers detected using immunocytochemistry staining and through the use of flow cytometery. Endothelial progenitor cells were transfected with plasmid vectors expressing human DDAH2 (DDAH2‐EPCs). Three days after gene transfer, positive transfected‐EPCs proliferation and DDAH activity were assayed. We observed colonies conformation and endothelium‐like morphology gradually in the third week of culture. Characterization results revealed positive expression of EPC surface markers CD106, Flk‐1, vWF, and CD34 using few identification techniques. Overexpression of DDAH2 increased citrulline production after 96 hours of transfection, 235.34 ± 0.69 vs 95.26 ± 5.76 ng/mL; P = .023. These results suggest that cell population with EPC characteristics can be simply isolated from rabbit bone marrow and successfully engineered to overexpress exogenous gene. In this study, we offer a feasible method to isolate and identify EPCs from bone marrow. In addition, an efficient transfection with a plasmid vector (without risk of interference) can be constructed a hybrid structure with EPC and DDAH2 gene to examine their function in vitro.     

Synergistic induction of interleukin-6 production and gene expression in human thymic epithelial cells by LPS and cytokines

We examined the ability of LPS and several cytokines (TNF-alpha, IL-1-beta, IFN-gamma, IL-4) to modulate IL-6 production by cultured human thymic epithelial cells (TEC). IL-6 activity was measured by the hybridoma growth factor biological activity. Moderate but detectable IL-6 activity was spontaneously produced in the presence of serum proteins. LPS as well as the cytokines TNF-alpha and IL-1-beta was a potent inducer of IL-6, increasing, respectively, IL-6 levels by 9-, 28-, and 75-fold (mean values) while IL-4 and IFN-gamma provoked no significant effect. Interestingly, clearly different kinetics were observed for IL-6 induction by the various activation agents, the maximal effect being reached at 24, 48, and 72 hr, respectively for LPS, TNF-alpha, and IL-1-beta. Moreover, a synergistic effect of TNF-alpha and either LPS or IL-1-beta was observed. Indeed, TEC incubated with the cytokines in combination at optimal doses produced 5- to 170-fold more IL-6 than TEC stimulated with the cytokines individually. Neutralizing anti-IL-6 polyclonal and monoclonal antibodies completely blocked hybridoma proliferation stimulating activity of TEC supernatants; thus, implying that this activity is essentially due to IL-6. In situ hybridization analysis of cytocentrifuged TEC with an mRNA antisense probe specific for human IL-6 and labeled with 35S demonstrated that up to 90% of TEC could be induced to express the IL-6 gene. Computer-aided quantification of IL-6 mRNA levels indicated that upon stimulation with TNF-alpha combined to LPS, both the numbers of cells expressing IL-6 mRNA and the amounts of cytoplasmic IL-6 mRNA per cell were increased. Taken altogether these results demonstrate that LPS and/or cytokines can modulate and synergistically stimulate IL-6 production. In addition to a possible role in regulating normal thymic T cell activation, the IL-6 produced by TEC could be of pathophysiological relevance in disregulated situations such as in hyperplastic thymuses from patients with myasthenia gravis.     

白血病细胞中不同启动子驱动外源基因表达能力差异分析

为了分析不同启动子在白血病细胞中驱动外源基因表达能力的差异,文章选择了4种含不同启动子EF1α、PGK、Ubiquitin和CMV驱动的GFP报告基因的慢病毒载体,用以感染4种不同的白血病细胞株——NB4、HL60、Kasumi和THP1,利用荧光显微镜、流式细胞仪和荧光定量PCR的方法检测其GFP表达效率,发现EF1α启动子驱动GFP表达的能力最强,CMV最弱,PGK和Ubiquitin则介于两者之间。该结果提示在白血病细胞中研究基因功能时,应根据不同的研究需求选择最为合适的启动子。     

In vitro study of the effects of ELF electric fields on gene expression in human epidermal cells

An acceleration of differentiation, at the expense of proliferation, is observed after exposure of various biological models to low frequency and low amplitude electric and electromagnetic fields. Following these results showing significant modifications, we try to identify the biological mechanism involved at the cell level through microarray screening. For this study, we use epidermis cultures harvested from human abdominoplasty. Two platinum electrodes are used to apply the electric signal. The gene expressions of 38,500 well‐characterized human genes are analyzed using Affymetrix® microarray U133 Plus 2.0 chips. The protocol is repeated on three different patients. After three periods of exposure, a total of 24 chips have been processed. After the application of ELF electric fields, the microarray analysis confirms a modification of the gene expression of epidermis cells. Particularly, four up‐regulated genes (DKK1, TXNRD1, ATF3, and MME) and one down‐regulated gene (MACF1) are involved in the regulation of proliferation and differentiation. Expression of these five genes was also confirmed by real‐time rtPCR in all samples used for microarray analysis. These results corroborate an acceleration of cell differentiation at the expense of cell proliferation. Bioelectromagnetics 32:28–36, 2011. © 2010 Wiley‐Liss, Inc.