Construction, Characterization and Application of Recombinant Porcine Deltacoronavirus Expressing Nanoluciferase

Porcine deltacoronavirus (PDCoV), an emerging enteropathogenic coronavirus, causes diarrhoea in suckling piglets and has the potential for cross-species transmission. No effective PDCoV vaccines or antiviral drugs are currently available. Here, we successfully generated an infectious clone of PDCoV strain CHN-HN-2014 using a combination of bacterial artificial chromosome (BAC)-based reverse genetics system with a one-step homologous recombination. The recued virus (rCHN-HN-2014) possesses similar growth characteristics to the parental virus in vitro. Based on the established infectious clone and CRISPR/Cas9 technology, a PDCoV reporter virus expressing nanoluciferase (Nluc) was constructed by replacing the NS6 gene. Using two drugs, lycorine and resveratrol, we found that the Nluc reporter virus exhibited high sensibility and easy quantification to rapid antiviral screening. We further used the Nluc reporter virus to test the susceptibility of different cell lines to PDCoV and found that cell lines derived from various host species, including human, swine, cattle and monkey enables PDCoV replication, broadening our understanding of the PDCoV cell tropism range. Taken together, our reporter viruses are available to high throughput screening for antiviral drugs and uncover the infectivity of PDCoV in various cells, which will accelerate our understanding of PDCoV.

Bioluminescence reporter for monitoring G2-phase cell cycle arrest in vivo

The bioengineered luciferase reporter has been widely used for monitoring of a variety of molecular events in living cells because of their ability to provide highly sensitive quantitation with broad linearity. In the present study, we made a cyclin A2-luciferase (CYCA-Luc) fusion protein and examined the utility of this optical reporter for monitoring G2-phase cell cycle arrest in living animals. In vitro luciferase assay and in vivo bioluminescence imaging assay showed that the lithium chloride (LiCl), G2-phase-specific drug, induced G2-phase arrest of cell cycle and increased the activity of this reporter under in vitro or in vivo conditions, and this reporter can also be potentially used in high-throughput screening efforts aimed at discovering novel anti-cancer drugs that will cause cell cycle arrest at the G2-phase in cultivated cell lines and animal models.

Injectable Biodegradable Chitosan-Alginate 3D Porous Gel Scaffold for mRNA Vaccine Delivery

mRNA vaccines have proven to be more stable, effective, and specific than protein/peptide-based vaccines in stimulating both humoral and cellular immune response. However, mRNA's fast degradation rate and low-transfection efficiency in vivo impede its potential in vaccination. Recent research in gene delivery has focused on nonviral vaccine carriers and either implantable or injectable delivery systems to improve transgene expression in vivo. Here, an injectable chitosan-alginate gel scaffold for the local delivery of mRNA vaccines is reported. Gel scaffold biodegradation rates and biocompatibility are quantified. Scaffold-mediated mRNA in vivo transgene expression as well as ovalbumin antigen specific cellular and humoral immune responses are evaluated in vivo. Luciferase reporter protein expression resulting from mRNA lipoplex-loaded gel scaffolds is five times higher than systemic injection. Compared to systemic injections of naked mRNA or mRNA:lipoplexes, elevated levels of T cell proliferation and IFN-γ secretion are seen with in vivo scaffold-mediated mRNA lipoplex delivery. Furthermore, a humoral response (ovalbumin antigen specific IgG levels) is observed as early as week 1 for scaffold-mediated mRNA lipoplex delivery, while protein-based immunization did not elicit IgG production until 2 weeks post-injection. Results suggest that injectable scaffold mRNA vaccine delivery maybe a viable alternative to traditional nucleic acid immunization methods.

Quantitative Analysis of Human T-Lymphotropic Virus Type 1 (HTLV-1) Infection Using Co-Culture with Jurkat LTR-Luciferase or Jurkat LTR-GFP Reporter Cells

Unlike HIV-1, HTLV-1 viral transmission requires cell-to-cell contacts, while cell-free virions are poorly infectious and almost absent from body fluids. Though the virus uses three nonexclusive mechanisms to infect new target cells: (1) MTOC polarization followed by formation of a virological synapse and viral transfer into a synaptic cleft, (2) genesis of a viral biofilm and its transfer of embedded viruses, or (3) HTLV-1 transmission using conduits. The Tax transactivator and the p8 viral proteins are involved in virological synapse and nanotube formation respectively.HTLV-1 transcription from the viral promoter (i.e., LTR) requires the Tax protein that is absent from the viral particle and is expressed after productive infection. The present chapter focuses on a series of protocols used to quantify HTLV-1 de novo infection of target cells. These techniques do not discriminate between the different modes of transmission, but allow an accurate measure of productive infection. We used cell lines that are stably transfected with LTR-GFP or LTR-luciferase plasmids and quantified Green Fluorescent Protein expression or luciferase activity, since both of them reflect Tax expression.

miRNAs Do Not Regulate Circadian Protein Synthesis in the Dinoflagellate Lingulodinium polyedrum

Dinoflagellates have been shown to express miRNA by bioinformatics and RNA blot (Northern) analyses. However, it is not yet known if miRNAs are able to alter gene expression in this class of organisms. We have assessed the possibility that miRNA may mediate circadian regulation of gene expression in the dinoflagellate Lingulodinium polyedrum using the Luciferin Binding Protein (LBP) as a specific example. LBP is a good candidate for regulation by miRNA since mRNA levels are constant over the daily cycle while protein synthesis is restricted by the circadian clock to a period of several hours at the start of the night phase. The transcriptome contains a potential DICER and an ARGONAUTE, suggesting the machinery for generating miRNAs is present. Furthermore, a probe directed against an abundant Symbiodinium miRNA cross reacts on Northern blots. However, L. polyedrum has no small RNAs detectable by ethidium bromide staining, even though higher plant miRNAs run in parallel are readily observed. Illumina sequencing of small RNAs showed that the majority of reads did not have a match in the L. polyedrum transcriptome, and those that did were almost all sense strand mRNA fragments. A direct search for 18-26 nucleotide long RNAs capable of forming duplexes with a 2 base 3' overhang detected 53 different potential miRNAs, none of which was able to target any of the known circadian regulated genes. Lastly, a microscopy-based test to assess synthesis of the naturally fluorescent LBP in single cells showed that neither double-stranded nor antisense lbp RNA introduced into cells by microparticle bombardment prior to the time of LBP synthesis were able to reduce the amount of LBP produced. Taken together, our results indicate that circadian control of protein synthesis in L. polyedrum is not mediated by miRNAs.

Bufalin inhibits pancreatic cancer by inducing cell cycle arrest via the c-Myc/NF-κB pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Bufalin, a cardiotonic steroid isolated from toad venom (bufo gargarizans Cantor or B. melanotictus Schneider), has widely demonstrated antitumor effects and exhibits potential antitumor activity in various human cancer cells lines.

AIMS OF THE STUDY

The main characteristic of cancers including pancreatic cancer is the ability of uncontrolled proliferation. The aim of this study is to clarify the underlying mechanism by which bufalin inhibits pancreatic cancer cell proliferation.

MATERIALS AND METHODS

The effect of bufalin on the suppression of tumor growth in vivo was studied in a bioluminescent mouse model generated using the pancreatic cancer cell line BxPC3-luc2 and the cytotoxicity was evaluated in BcPc3 and Sw1990 cells with MTT. Flow cytometry and western blotting analyses were utilized to detect the effect of bufalin on the cell cycle and to detect the cell cycle-related proteins, respectively. Then, a luciferase reporter assay was applied to screen the activity of potent transcription factors following bufalin exposure and their expression was detected by western blotting.

RESULTS

Bufalin suppressed tumor growth in a bioluminescence mouse model generated using BxPC3-luc2 cells and inhibited cell proliferation in vitro through inducing cell cycle arrest at S phase. Bufalin treatment inhibited cyclin D1 and cyclin E1 expression and therefore increased expression of p27, a regulatory molecular that controls cell cycle transition from S to G2 phase. Furthermore, luciferase reporter screening studies revealed that bufalin inhibited the expression and activity of the transcription factors c-Myc and NF-κB, which might cause cell cycle arrest at S phase and the inhibition of cell proliferation.

CONCLUSIONS

Taken together, our results indicate that bufalin can inhibit pancreatic cancer by targeting c-Myc, thus suggesting that the mechanism of c-Myc regulation by bufalin might be worthy of further study regarding its potential as a therapeutic target for pancreatic cancer treatment.

Different Types of Luciferase Reporters Show Distinct Susceptibility to T3-Evoked Downregulation

BACKGROUND

The firefly luciferase reporter protein is a crucial tool for studies targeting a broad range of biological questions. Importantly, luciferase assays are also widely used to explore mechanisms underlying thyroid hormone dependent regulation of gene expression. However, it was demonstrated that the firefly luciferase reporter is subject to triiodothyronine (T3)-evoked, promoter independent downregulation that is mediated by the thyroid hormone receptor. Since this effect can interfere with readout accuracy, the study aimed to find luciferase reporters that are not susceptible to this phenomenon.

METHODS

Luciferase reporter constructs were generated under the control of a minimal thymidine kinase (TK) promoter and transiently transfected into JEG-3 cells to test their activity upon T3 treatment.

RESULTS

Activity of the TK-(dCpG)Luc encoding a synthetic (dCpG)Luciferase and TK-NanoLuc expressing the NanoLuc reporter was not significantly changed by T3 treatment while the firefly luciferase control was suppressed by ∼2.6-fold. T3 also downregulated the activity of Renilla luciferase by ∼30%.

CONCLUSIONS

Novel types of luciferase reporters, especially the synthetic (dCpG)Luciferase, can be more accurate to study T3-regulated gene expression than the classical firefly luciferase reporter. Renilla luciferase, a popular transfection control of dual luciferase assays, should be used with caution in conditions with T3 treatment.

Drug-Encoded Biomarkers for Monitoring Biological Therapies

Blood tests are necessary, easy-to-perform and low-cost alternatives for monitoring of oncolytic virotherapy and other biological therapies in translational research. Here we assessed three candidate proteins with the potential to be used as biomarkers in biological fluids: two glucuronidases from E. coli (GusA) and Staphylococcus sp. RLH1 (GusPlus), and the luciferase from Gaussia princeps (GLuc). The three genes encoding these proteins were inserted individually into vaccinia virus GLV-1h68 genome under the control of an identical promoter. The three resulting recombinant viruses were used to infect tumor cells in cultures and human tumor xenografts in nude mice. In contrast to the actively secreted GLuc, the cytoplasmic glucuronidases GusA and GusPlus were released into the supernatants only as a result of virus-mediated oncolysis. GusPlus resulted in the most sensitive detection of enzyme activity under controlled assay conditions in samples containing as little as 1 pg/ml of GusPlus, followed by GusA (25 pg/ml) and GLuc (≥375 pg/ml). Unexpectedly, even though GusA had a lower specific activity compared to GusPlus, the substrate conversion in the serum of tumor-bearing mice injected with the GusA-encoding virus strains was substantially higher than that of GusPlus. This was attributed to a 3.2 fold and 16.2 fold longer half-life of GusA in the blood stream compared to GusPlus and GLuc respectively, thus a more sensitive monitor of virus replication than the other two enzymes. Due to the good correlation between enzymatic activity of expressed marker gene and virus titer, we conclude that the amount of the biomarker protein in the body fluid semiquantitatively represents the amount of virus in the infected tumors which was confirmed by low light imaging. We found GusA to be the most reliable biomarker for monitoring oncolytic virotherapy among the three tested markers.

Weight gain and inflammation regulate aromatase expression in male adipose tissue, as evidenced by reporter gene activity

Obesity and white adipose tissue (WAT) inflammation are associated with enhanced aromatization in women, but little is known about the regulation of aromatase (CYP19A1) gene expression in male WAT. We investigated the impact of weight gain and WAT inflammation on the regulation of CYP19A1 in males, by utilizing the hARO-Luc aromatase reporter mouse model containing a >100-kb 5'-region of the human CYP19A1 gene. We show that hARO-Luc reporter activity is enhanced in WAT of mice with increased adiposity and inflammation. Dexamethasone and TNFα, as well as forskolin and phorbol 12-myristate 13-acetate, upregulate hARO-Luc activity, suggesting the involvement of promoters I.4 and I.3/II. Furthermore, we show that diet enriched with antioxidative plant polyphenols attenuates WAT inflammation and hARO-Luc activity in obese males. In conclusion, our data suggest that obesity-associated WAT inflammation leads to increased peripheral CYP19A1 expression in males, and that polyphenol-enriched diet may have the potential to attenuate excessive aromatization in WAT of obese men.

Discovery, adaptation and transcriptional activity of two tick promoters: Construction of a dual luciferase reporter system for optimization of RNA interference in rhipicephalus (boophilus) microplus cell lines

Dual luciferase reporter systems are valuable tools for functional genomic studies, but have not previously been developed for use in tick cell culture. We evaluated expression of available luciferase constructs in tick cell cultures derived from Rhipicephalus (Boophilus) microplus, an important vector of bovine babesiosis and anaplasmosis. Commercial promoters were evaluated for transcriptional activity driving luciferase expression in the tick cell lines. The human phosphoglycerate kinase (PGK) promoter resulted in detectable firefly luciferase activity within 2 days post-transfection of the R. microplus cell line BME26, with maximal activity at 5 days post-transfection. Several other promoters were weaker or inactive in the tick cells, prompting identification and assessment of transcriptional activity of the homologous ribosomal protein L4 (rpL4, GenBank accession no.: KM516205) and elongation factor 1α (EF-1α, GenBank accession no.: KM516204) promoters cloned from R. microplus. Evaluation of luciferase expression driven by various promoters in tick cell culture resulted in selection of the R. microplus rpL4 promoter and the human PGK promoter driving transcription of sequences encoding modified firefly and NanoLuc® luciferases for construction of a dual luciferase reporter system for use in tick cell culture.

Liver suction-mediated transfection in mice using a pressure-controlled computer system

We previously developed an in vivo tissue suction-mediated transfection method (denoted as the tissue suction method) for naked nucleic acids, such as plasmid DNA (pDNA) and small interfering RNA (siRNA), in mice. However, it remains unclear whether the suction pressure conditions affect the results of this method. Therefore, in the present study, we assembled a computer system to control the suction pressure and investigate the effects of the suction pressure conditions on the efficiency of the liver suction transfection of naked pDNA that encodes luciferase in mice. Using the developed system, we examined the effects of the minimum magnitude of the suction pressure, suction pressure waveform, and suction times of the luciferase expression level in mice livers. We determined that the liver suction method at 5 kPa was not only effective but also caused the lowest hepatic toxicity in mice. Additionally, the results indicated that the suction pressure waveform affects the luciferase expression levels, and a single period of suction on the targeted portion of the liver is sufficient for transfection. Thus, the developed system is useful for performing the tissue suction method with high accuracy and safety.

Generation of luciferase-expressing Leishmania infantum chagasi and assessment of miltefosine efficacy in infected hamsters through bioimaging

Background

The only oral drug available for the treatment of leishmaniasis is miltefosine, described and approved for visceral leishmaniasis in India. Miltefosine is under evaluation for the treatment of cutaneous leishmaniasis in the Americas although its efficacy for the treatment of human visceral leishmaniasis caused by Leishmania infantum chagasi has not been described. Drug efficacy for visceral leishmaniasis is ideally tested in hamsters, an experimental model that mimics human disease. Luciferase has been validated as a quantitative tool for the determination of parasite burden in experimental leishmaniasis. However, there are no reports of luciferase detection in the model of progressive visceral leishmaniasis in hamsters. Therefore, the aims of this study were to generate recombinant Leishmania infantum chagasi expressing the luciferase gene (Lc-LUC), characterize the biological properties of this transgenic line as compared with the wild-type parasites and evaluate miltefosine effectiveness in Lc-LUC infected hamsters.

Methodology/Principal Findings

A transgenic line containing a luciferase encoding gene integrated into the ribosomal DNA locus was obtained and shown to produce bioluminescence which correlated with the number of parasites. Lc-LUC growth curves and susceptibility to pentavalent antimony and miltefosine in vitro were indistinguishable from the wild-type parasites. The effectiveness of pentavalent antimony was evaluated in Lc-LUC infected hamsters through bioimaging and determination of Leishman Donovan Units. Both methods showed concordant results. Miltefosine was effective in the treatment of Lc-LUC-infected hamsters, as demonstrated by the reduction in parasite burden in a dose-dependent manner and by prolongation of animal survival.

Conclusions/Significance

Luciferase expressing parasites are a reliable alternative for parasite burden quantification in hamsters with advantages such as the possibility of estimating parasite load before drug treatment and therefore allowing distribution of animals in groups with equivalent mean parasite burden. Miltefosine was effective in vivo in an L. infantum chagasi experimental model of infection.

Studies to determine drug efficacy in experimental models of leishmaniasis involve several difficulties. Parasite quantification in tissues is generally done by techniques that are laborious and time consuming, such as limiting dilution and microscopic counting of amastigotes in imprinting of infected organs. To overcome some of these problems, we described in this study an experimental model of visceral leishmaniasis (VL) using parasites expressing luciferase. Leishmania infantum chagasi, the etiologic agent of VL in Latin America, was genetically manipulated to express the luciferase gene in order to produce light upon addition of luciferin. We inoculated these parasites in hamsters and, about one month post-infection, we detected light in the abdominal and/or pelvic region, indicating widespread infection. We compared the data obtained by bioluminescence with microscopic counting of amastigotes in imprinting of infected spleens and both methods showed concordant results. Aiming to validate our model to be used in drug effectiveness experiments, we performed the experimental treatment with pentavalent antimony, the first choice drug for VL treatment in Latin America. We also treated infected hamsters with miltefosine, the only oral drug used for leishmaniasis treatment and for which effectiveness against L. infantum chagasi infected hamsters had not yet been reported.

Pax3 and hippo signaling coordinate melanocyte gene expression in neural crest

Loss of Pax3, a developmentally regulated transcription factor expressed in premigratory neural crest, results in severe developmental defects and embryonic lethality. Although Pax3 mutations produce profound phenotypes, the intrinsic transcriptional activation exhibited by Pax3 is surprisingly modest. We postulated the existence of transcriptional coactivators that function with Pax3 to mediate developmental functions. A high-throughput screen identified the Hippo effector proteins Taz and Yap65 as Pax3 coactivators. Synergistic coactivation of target genes by Pax3-Taz/Yap65 requires DNA binding by Pax3, is Tead independent, and is regulated by Hippo kinases Mst1 and Lats2. In vivo, Pax3 and Yap65 colocalize in the nucleus of neural crest progenitors in the dorsal neural tube. Neural crest deletion of Taz and Yap65 results in embryo-lethal neural crest defects and decreased expression of the Pax3 target gene, Mitf. These results suggest that Pax3 activity is regulated by the Hippo pathway and that Pax factors are Hippo effectors.

Development of a multifunctional luciferase reporters system for assessing endoplasmic reticulum-targeting photosensitive compounds

Photodynamic therapy (PDT) is a recently developed antitumor modality utilizing the generation of reactive oxygen species (ROS), through light irradiation of photosensitizers (PSs) localized in tumor. Interference with proper functioning of endoplasmic reticulum (ER) by ER-targeting PDT is a newly proposed strategy to achieve tumor cell death. The aim of this study is to establish a multifunctional model to screen and assess ER-targeting PSs based on luciferase reporters system. Upregulation of GRP78 is a biomarker for the onset of ER stress. CHOP is a key initiating player in ER stress-induced cell death. Here, the most sensitive fragments of GRP78 and CHOP promoters responding to ER-targeting PDT were mapped and cloned into pGL3-basic vector, forming -702/GRP78-Luc and -443/CHOP-Luc construct, respectively. We demonstrated that -702/GRP78-Luc expression can be used to indicate the ER-targeting of PSs, meanwhile estimate the ROS level induced by low-dose ER-targeting PDT. Moreover, the luciferase signaling of -443/CHOP-Luc showed highly consistence with apoptosis rate caused by ER-targeting PDT, suggesting that -443/CHOP-Luc can evaluate the antitumor properties of PSs. Hypericin, Foscan® and methylene blue were applied to verify the sensitivity and reliability of our model. These results proved that GRP78-CHOP model may be suitable to screen ER-targeting photosensitive compounds with lower cost and higher sensitivity than traditional ways.

Bioluminescence imaging of Chlamydia muridarum ascending infection in mice

Chlamydial pathogenicity in the upper genital tract relies on chlamydial ascending from the lower genital tract. To monitor chlamydial ascension, we engineered a luciferase-expressing C. muridarum. In cells infected with the luciferase-expressing C. muridarum, luciferase gene expression and enzymatic activity (measured as bioluminescence intensity) correlated well along the infection course, suggesting that bioluminescence can be used for monitoring chlamydial replication. Following an intravaginal inoculation with the luciferase-expressing C. muridarum, 8 of 10 mice displayed bioluminescence signal in the lower with 4 also in the upper genital tracts on day 3 after infection. By day 7, all 10 mice developed bioluminescence signal in the upper genital tracts. The bioluminescence signal was maintained in the upper genital tract in 6 and 2 mice by days 14 and 21, respectively. The bioluminescence signal was no longer detectable in any of the mice by day 28. The whole body imaging approach also revealed an unexpected airway infection following the intravaginal inoculation. Although the concomitant airway infection was transient and did not significantly alter the genital tract infection time courses, caution should be taken during data interpretation. The above observations have demonstrated that C. muridarum can not only achieve rapid ascending infection in the genital tract but also cause airway infection following a genital tract inoculation. These findings have laid a foundation for further optimizing the C. muridarum intravaginal infection murine model for understanding chlamydial pathogenic mechanisms.

Package of NDV-pseudotyped HIV-Luc virus and its application in the neutralization assay for NDV infection

Newcastle disease virus (NDV) is a member of the Paramyxovirinae subfamily and can infect most species of birds. It has been a great threat for the poultry industry all around the world. In this report, we successfully produced infectious pseudotyped pNL4-3-Luc-R⁻E⁻ (HIV-Luc) viruses with the HN and F envelope proteins of NDV. Further investigation revealed the cytoplasmic domains of HN and F, especially HN, plays a significant role in the infection efficiency of these pseudotyped HIV-Luc viruses. Replacement of, or direct fusion to the cytoplasmic domain of the HN protein by that of vesicular stomatitis virus G (VSV-G) could greatly enhance or destroy the infective potential of HN and F-pseudotyped (NDV-pseudotyped) HIV-Luc virus. We further established a novel neutralization assay to evaluate neutralizing antibodies against NDV with the NDV-pseudotyped HIV-Luc viruses. Comparative neutralization data indicate that the results determined by using the NDV-pseudotyped HIV-Luc viruses are as reliable as those by the conventional virus-neutralization assay (VN test) with native NDV. Moreover, the results show that the novel neutralization assay is more sensitive than the VN test.

Enhanced Expression of Apoptin by the Myc–Max Binding Motif and SV40 Enhancer for SCLC Gene Therapy

Apoptin is derived from chicken anemia virus (CAV) and known to induce tumor specific apoptosis but not normal cells. The aim of this study was to use increased expression of apoptin by the Myc-Max response element (MMRE) and SV40 enhancer in small-cell lung cancer (SCLC) gene therapy. To investigate the possibility of the utilization of the MMRE, apoptin, and SV40 promoter/enhancer in targeted cancer gene therapy, adenovirus vector expressing apoptin controlled by the MMRE, and SV40 promoter/enhancer was constructed. Ad-MMRE-apoptin-enh infected SCLC cells were significantly suppressed and induced apoptosis more than those of Ad-apoptin or Ad-apoptin-enh. Infection with Ad-MMRE-apoptin-enh of normal cells did not increase apoptosis. About 85% of SCLC tumors show overexpression of the myc family, so the increased expression of apoptin by MMRE and SV40 enhancer can be used in targeted SCLC gene therapy. These results indicate that apoptin expression was increased by the MMRE and SV40 promoter/enhancer, and that this strategy can be used in SCLC targeted cancer gene therapy.

5-Bromodeoxyuridine Increases Transient Expression of Ectopic Genes in Human Cells

Ectopic genes transferred to cells are temporally expressed, although this phenomenon has not yet been well characterized. We found that 5-bromodeoxyuridine dramatically increased transient expression of ectopic genes in human cells. This effect was elicited by adding 5-bromodeoxyuridine prior to or after transfection. No promoter specificity was observed. Real time PCR analysis showed an approximately 2-fold increase in mRNA levels. Since 5-bromodeoxyuridine decondenses heterochromatin and changes the nuclear envelope, these changes might affect transcriptional and post-transcriptional events in the gene expression of plasmids.

Functional polymorphisms of TLR8 are associated with hepatitis C virus infection

Chronic hepatitis C virus (HCV) infection is a worldwide threat to public health. Toll-like receptor 8 (TLR8) is critical for eliminating RNA viruses, and variation within the TLR8 gene may alter the function of TLR8 in response to HCV infection. Our previous study demonstrated that the TLR8-129G>C (rs3764879) and TLR8+1G>A (rs3764880) variants were in complete linkage disequilibrium, and that the frequency of TLR8-129C/+1A was significantly higher in male patients with HCV infection compared with the healthy controls. In the present study, we found that the promoter activity of TLR8-129G was higher than that of TLR8-129C in THP-1 cells. Moreover, TLR8-129G mRNA stability and competitive DNA-binding ability were significantly lower than that of TLR8-129C. To investigate the functional effects of TLR8 polymorphisms, we compared the nuclear factor-κB (NF-κB)-driven luciferase activity in HEK293 cells transfected with the TLR8 variants. TLR8+1A plasmids induced less NF-κB signalling than did those transfected with TLR8+1G after 20 μm CL075 (P = 0.011) stimulation. We also analysed the mRNA expression and cytokine production in whole blood and monocytes from people of various genotypes stimulated ex vivo by the interferon-γ and TLR7/8 agonist CL075, R848. TLR8 expression in CD14⁺ cells derived from volunteers with TLR8-129G/+1G was significantly higher than that derived from TLR8-129C/+1A, and interleukin-12p40 production was higher in volunteers with TLR8-129G/+1G after stimulation. The data indicate that variations in TLR8 genes may modulate immune responses during HCV infection.

Examination of artificial MiRNA mimics with centered-site complementarity for gene targeting

BACKGROUND

MiRNA primarily acts to repress gene expression at the post-transcriptional level through imperfect complementarity of its 5' region to the "seed site" in the 3' untranslated region of target mRNAs, with its "3'-supplementary site" and "center site" also playing important roles under certain circumstances. The aim of this study was to test if artificial miRNA mimics (miR-Mimics) that are designed to target the "centered sites" without "seed sites" complementarity are able to repress gene expression as natural miRNAs.

METHODS

We designed miR-Mimics carrying centered-site matches (CS-miR-Mimics) or seed-site matches (SS-miR-Mimics) and siRNA to two antiapoptotic genes BCL2 and AKT1. We tested the gene targeting of these constructs using real-time RT-PCR and Western blot to quantify mRNA and protein levels of BCL2 and AKT1, respectively, luciferase reporter gene assay to investigate the interaction between miR-Mimics and their target sites, and cell survival assay to study the functional outcomes of the miR-Mimics.

RESULTS

We found that CS-miR-Mimic, SS-miR-Mimic and siRNA, all down regulated the mRNA and protein levels of their cognate target BCL2 or AKT1 in a concentration-dependent manner. Luciferase reporter gene assay further confirmed the functional interactions of CS-miR-Mimic, SS-miR-Mimic and siRNA with their target sites. We then observed that the miR-Mimics and siRNAs were all able to induce cell death, as indicated by the reduced survival rate of cells.

CONCLUSIONS

We have provided evidence for the feasibility of CS-miR-Mimics for post-transcriptional repression of genes, which can be designed to have reduced numbers of seed type off-target sites compared to the number of target sites from an average endogenous seed-site miRNA. CS-miR-Mimics may be a novel approach for miRNA research requiring miRNA gain-of-function.

In vivo imaging of trypanosome-brain interactions and development of a rapid screening test for drugs against CNS stage trypanosomiasis

HUMAN AFRICAN TRYPANOSOMIASIS (HAT) MANIFESTS IN TWO STAGES OF DISEASE: firstly, haemolymphatic, and secondly, an encephalitic phase involving the central nervous system (CNS). New drugs to treat the second-stage disease are urgently needed, yet testing of novel drug candidates is a slow process because the established animal model relies on detecting parasitemia in the blood as late as 180 days after treatment. To expedite compound screening, we have modified the GVR35 strain of Trypanosoma brucei brucei to express luciferase, and have monitored parasite distribution in infected mice following treatment with trypanocidal compounds using serial, non-invasive, bioluminescence imaging. Parasites were detected in the brains of infected mice following treatment with diminazene, a drug which cures stage 1 but not stage 2 disease. Intravital multi-photon microscopy revealed that trypanosomes enter the brain meninges as early as day 5 post-infection but can be killed by diminazene, whereas those that cross the blood-brain barrier and enter the parenchyma by day 21 survived treatment and later caused bloodstream recrudescence. In contrast, all bioluminescent parasites were permanently eliminated by treatment with melarsoprol and DB829, compounds known to cure stage 2 disease. We show that this use of imaging reduces by two thirds the time taken to assess drug efficacy and provides a dual-modal imaging platform for monitoring trypanosome infection in different areas of the brain.

[Trigger factor dependent refolding of bacterial luciferases in Escherichia coli cells: kinetics, efficiency and effect of the bichaperone system, DnaKJE-ClpB]

Here were determined the basic parameters of the Tigger Factor (TF) -dependent refolding of thermal inactivated bacterial luciferases. The TF-dependent refolding is less efficient and requires more time than DnaKJE-dependent refolding. The increase in the intracellular concentration of TF leads to an apparent decrease in the level of the thermal inactivated bacterial luciferase refolding. For thermolabile luciferases, the level of TF-dependent refolding is significantly higher, than for thermostable luciferases: 30-40%--for the thermolabile Aliivibrio fischeri and Photobacterium leiognathi luciferases, and 10 and 0.5% for the thermostable Vibrio harveyi and Photorhabdus luminescens luciferases, respectively. The negative effect of the ClpB protein on the TF-dependent refolding was shown: in Escherichia coli clpB::kan TF-dependent refolding is more efficient than in the E. coli clpB+.

The extracellular matrix regulates MaeuCath1a gene expression

We have previously shown that the gene for MaeuCath1, a cathelicidin secreted in wallaby milk is alternately spliced into two variants, MaeuCath1a and MaeuCath1b which are temporally regulated in order to provide antimicrobial protection to the newborn and stimulate mammary growth, respectively. The current study investigated the extracellular matrix (ECM) for its regulatory role in MaeuCath1 gene expression. Reverse transcription qPCR using RNA isolated from mammary epithelial cells (WallMEC) cultured on ECM showed that ECM regulates MaeuCath1a gene expression in a lactation phase-dependent manner. Luciferase reporter-based assays and in silico analysis of deletion fragments of the 2245bp sequence upstream of the translation start site identified ECM-dependent positive regulatory activity in the -709 to -15 region and repressor activity in the -919 to -710 region. Electrophoretic Gel Mobility Shift Assays (EMSA) using nuclear extract from ECM-treated WallMEC showed differential band shift in the -839 to -710 region.

Illuminating cancer systems with genetically engineered mouse models and coupled luciferase reporters in vivo

Bioluminescent imaging (BLI) is a powerful noninvasive tool that has dramatically accelerated the in vivo interrogation of cancer systems and longitudinal analysis of mouse models of cancer over the past decade. Various luciferase enzymes have been genetically engineered into mouse models (GEMM) of cancer, which permit investigation of cellular and molecular events associated with oncogenic transcription, posttranslational processing, protein-protein interactions, transformation, and oncogene addiction in live cells and animals. Luciferase-coupled GEMMs ultimately serve as a noninvasive, repetitive, longitudinal, and physiologic means by which cancer systems and therapeutic responses can be investigated accurately within the autochthonous context of a living animal.

MicroRNA-31 sensitizes human breast cells to apoptosis by direct targeting of protein kinase C epsilon (PKCepsilon)

MicroRNAs post-transcriptionally regulate gene expression and thereby contribute to the modulation of numerous complex and disease-relevant cellular phenotypes, including cell proliferation, cell motility, apoptosis, and stress response. In breast cancer cell systems, miR-31 has been shown to inhibit cell migration, invasion, and metastasis. Here, we link enhanced expression of miR-31 to the inhibition of the oncogenic NF-κB pathway, thus supporting the tumor-suppressive function of this microRNA. We identified protein kinase C epsilon (PKCε encoded by the PRKCE gene) as a novel direct target of miR-31 and show that down-regulation of PKCε results in impaired NF-κB signaling, enhanced apoptosis, and increased sensitivity of MCF10A breast epithelial and MDA-MB-231 triple-negative breast cancer cells toward ionizing radiation as well as treatment with chemotherapeutics. Mechanistically, we attribute this sensitization to anti-cancer treatments to the PRKCE-mediated down-regulation of the anti-apoptotic factor BCL2. In clinical breast cancer samples, high BCL2 expression was associated with poor prognosis. Furthermore, we found an inverse correlation between miR-31 and BCL2 expression, highlighting the functional relevance of the indirect down-regulation of BCL2 via direct targeting of PRKCE by miR-31.

Transcriptional activation of Reg2 and Reg3β genes by glucocorticoids and interleukin-6 in pancreatic acinar and islet cells

Reg family proteins are expressed in the pancreas and involved in pancreatitis and islet β-cell growth. In order to explore transcriptional control, we transfected luciferase reporter genes driven by Reg promoters into acinar AR42J and islet MIN6 cells. Dexamethasone (DEX) significantly increased the promoter expression of Reg2 and Reg3β genes and the levels of endogenous Reg3β mRNA and protein in AR42J cells. DEX-induced promoter activation was inhibited by the inhibitor of poly(ADP-ribose) polymerase, nicotinamide. In MIN6 cells, DEX moderately stimulated the transcription of Reg3β but not Reg2 promoter. While IL-6 alone had no effect, coculture with DEX produced a remarkable synergism on Reg3β gene transcription, which was abolished by nicotinamide. Our results demonstrated a significant and direct stimulation of Reg2 and Reg3β genes by glucocorticoids, all three were activated in response to inflammation such as in pancreatitis. Prominent stimulation of specific Reg genes by glucocorticoids may constitute a functional synergism.

Synthesis of 6-azaprogesterone and 19-hydroxy-6-azasteroids

19-Hydroxy-6-azapregnanes were obtained from pregnenolone via a 7-azido-5-oxo-6-nor-5,7-secopregnane intermediate. The 6-azapregnane core was built in good yield in a straightforward way from the secosteroid, by means of a Staudinger (aza-Wittig) reaction. Finally the 19-hydroxy-6-azapregnane was transformed into 19-hydroxy-6-azaprogesterone (that cyclized spontaneously to the 19→3 hemiketal) and 6-azaprogesterone. The 6-azapregnanes lacked agonistic/antagonistic activity on the progesterone receptor.

Promoter independent abortive transcription assays unravel functional interactions between TFIIB and RNA polymerase

TFIIB-like general transcription factors are required for transcription initiation by all eukaryotic and archaeal RNA polymerases (RNAPs). TFIIB facilitates both recruitment and post-recruitment steps of initiation; in particular, TFIIB stimulates abortive initiation. X-ray crystallography of TFIIB-RNAP II complexes shows that the TFIIB linker region penetrates the RNAP active center, yet the impact of this arrangement on RNAP activity and underlying mechanisms remains elusive. Promoter-independent abortive initiation assays exploit the intrinsic ability of RNAP enzymes to initiate transcription from nicked DNA templates and record the formation of the first phosphodiester bonds. These assays can be used to measure the effect of transcription factors such as TFIIB and RNAP mutations on abortive transcription.

Regulation of the human hydroxysteroid sulfotransferase (SULT2A1) by RORα and RORγ and its potential relevance to human liver diseases

The retinoid-related orphan receptors (RORs) were postulated to have functions in tissue development and circadian rhythm. In this study, we revealed a novel function of RORα (NR1F1) and RORγ (NR1F3) in regulating the human hydroxysteroid sulfotransferase (SULT2A1), a phase II conjugating enzyme known to sulfonate bile acids, hydroxysteroid dehydroepiandrosterone, and related androgens. A combination of promoter reporter gene assay and EMSA and chromatin immunoprecipitation (ChIP) assays showed that both RORα and RORγ transactivated the SULT2A1 gene promoter through their binding to a ROR response element found in the SULT2A1 gene promoter. Interestingly, this ROR response element overlaps with a previously reported constitutive androstane receptor response element on the same promoter. Down-regulation of RORα and/or RORγ by small interfering RNA inhibited the expression of endogenous SULT2A1. In primary human hepatocytes and human livers, we found a positive correlation between the expression of SULT2A1 and RORs, which further supported the regulation of SULT2A1 by RORs. We also found that the expression of RORα and RORγ was impaired in several liver disease conditions, such as steatosis/steatohepatitis, fibrosis, and hepatocellular carcinoma. The positive regulation of human SULT2A1 by RORs is opposite to the negative regulation of Sult2a1 by RORs in rodents. In summary, our results established SULT2A1 as a novel ROR target gene. The expression of RORs is a potential predictor for the expression of SULT2A1 as well as disease conditions.

In vivo imaging enables high resolution preclinical trials on patients' leukemia cells growing in mice

Background

Xenograft mouse models represent helpful tools for preclinical studies on human tumors. For modeling the complexity of the human disease, primary tumor cells are by far superior to established cell lines. As qualified exemplary model, patients’ acute lymphoblastic leukemia cells reliably engraft in mice inducing orthotopic disseminated leukemia closely resembling the disease in men. Unfortunately, disease monitoring of acute lymphoblastic leukemia in mice is hampered by lack of a suitable readout parameter.

Design and Methods

Patients’ acute lymphoblastic leukemia cells were lentivirally transduced to express the membrane-bound form of Gaussia luciferase. In vivo imaging was established in individual patients’ leukemias and extensively validated.

Results

Bioluminescence in vivo imaging enabled reliable and continuous follow-up of individual mice. Light emission strictly correlated to post mortem quantification of leukemic burden and revealed a logarithmic, time and cell number dependent growth pattern. Imaging conveniently quantified frequencies of leukemia initiating cells in limiting dilution transplantation assays. Upon detecting a single leukemia cell within more than 10,000 bone marrow cells, imaging enabled monitoring minimal residual disease, time to tumor re-growth and relapse. Imaging quantified therapy effects precisely and with low variances, discriminating treatment failure from partial and complete responses.

Conclusions

For the first time, we characterized in detail how in vivo imaging reforms preclinical studies on patient-derived tumors upon increasing monitoring resolution. In the future, in vivo imaging will enable performing precise preclinical studies on a broad range of highly demanding clinical challenges, such as treatment failure, resistance in leukemia initiating cells, minimal residual disease and relapse.

Butyrate produced by commensal bacteria potentiates phorbol esters induced AP-1 response in human intestinal epithelial cells

The human intestine is a balanced ecosystem well suited for bacterial survival, colonization and growth, which has evolved to be beneficial both for the host and the commensal bacteria. Here, we investigated the effect of bacterial metabolites produced by commensal bacteria on AP-1 signaling pathway, which has a plethora of effects on host physiology. Using intestinal epithelial cell lines, HT-29 and Caco-2, stably transfected with AP-1-dependent luciferase reporter gene, we tested the effect of culture supernatant from 49 commensal strains. We observed that several bacteria were able to activate the AP-1 pathway and this was correlated to the amount of short chain fatty acids (SCFAs) produced. Besides being a major source of energy for epithelial cells, SCFAs have been shown to regulate several signaling pathways in these cells. We show that propionate and butyrate are potent activators of the AP-1 pathway, butyrate being the more efficient of the two. We also observed a strong synergistic activation of AP-1 pathway when using butyrate with PMA, a PKC activator. Moreover, butyrate enhanced the PMA-induced expression of c-fos and ERK1/2 phosphorylation, but not p38 and JNK. In conclusion, we showed that SCFAs especially butyrate regulate the AP-1 signaling pathway, a feature that may contribute to the physiological impact of the gut microbiota on the host. Our results provide support for the involvement of butyrate in modulating the action of PKC in colon cancer cells.

Bacterial resistance to antisense peptide phosphorodiamidate morpholino oligomers

Peptide phosphorodiamidate morpholino oligomers (PPMOs) are synthetic DNA mimics that bind cRNA and inhibit bacterial gene expression. The PPMO (RFF)(3)RXB-AcpP (where R is arginine, F, phenylalanine, X is 6-aminohexanoic acid, B is β-alanine, and AcpP is acyl carrier protein) is complementary to 11 bases of the essential gene acpP (which encodes acyl carrier protein). The MIC of (RFF)(3)RXB-AcpP was 2.5 μM (14 μg/ml) in Escherichia coli W3110. The rate of spontaneous resistance of E. coli to (RFF)(3)RXB-AcpP was 4 × 10(-7) mutations/cell division. A spontaneous (RFF)(3)RXB-AcpP-resistant mutant (PR200.1) was isolated. The MIC of (RFF)(3)RXB-AcpP was 40 μM (224 μg/ml) for PR200.1. The MICs of standard antibiotics for PR200.1 and W3110 were identical. The sequence of acpP was identical in PR200.1 and W3110. PR200.1 was also resistant to other PPMOs conjugated to (RFF)(3)RXB or peptides with a similar composition or pattern of cationic and nonpolar residues. Genomic sequencing of PR200.1 identified a mutation in sbmA, which encodes an active transport protein. In separate experiments, a (RFF)(3)RXB-AcpP-resistant isolate (RR3) was selected from a transposome library, and the insertion was mapped to sbmA. Genetic complementation of PR200.1 or RR3 with sbmA restored susceptibility to (RFF)(3)RXB-AcpP. Deletion of sbmA caused resistance to (RFF)(3)RXB-AcpP. We conclude that resistance to (RFF)(3)RXB-AcpP was linked to the peptide and not the phosphorodiamidate morpholino oligomer, dependent on the composition or repeating pattern of amino acids, and caused by mutations in sbmA. The data further suggest that (RFF)(3)R-XB PPMOs may be transported across the plasma membrane by SbmA.

Androgen receptor repression of gonadotropin-releasing hormone gene transcription via enhancer 1

Gonadotropin-releasing hormone (GnRH) plays a major role in the hypothalamic-pituitary-gonadal (HPG) axis, and synthesis and secretion of GnRH are regulated by gonadal steroid hormones. Disruptions in androgen levels are involved in a number of reproductive defects, including hypogonadotropic hypogonadism and polycystic ovarian syndrome. Androgens down-regulate GnRH mRNA synthesis in vivo and in vitro via an androgen receptor (AR)-dependent mechanism. Methyltrienolone (R1881), a synthetic AR agonist, represses GnRH expression through multiple sites in the proximal promoter. In this study, we show AR also represses GnRH transcription via the major enhancer (GnRH-E1). A multimer of the -1800/-1766 region was repressed by R1881 treatment. Mutation of two bases, -1792 and -1791, resulted in decreased basal activity and a loss of AR-mediated repression. AR bound to the -1796/-1791 sequence in electrophoretic mobility shift assays, indicating a direct interaction with DNA or other transcription factors in this region. We conclude that AR repression of GnRH-E1 acts via multiple AR-responsive regions, including the site at -1792/-1791.

ERα/E2 signaling suppresses the expression of steroidogenic enzyme genes via cross-talk with orphan nuclear receptor Nur77 in the testes

Estrogen receptor alpha (ERα) has been reported to affect steroidogenesis in testicular Leydig cells, but its molecular mechanism remains unclear. Here, we investigate the effect of estrogen and ERα on Nur77, a major transcription factor that regulates the expression of steroidogenic enzyme genes. In MA-10 Leydig cells, estradiol (E2) treatment, and interestingly ERα overexpression, suppressed the cAMP-induced and Nur77-activated promoter activity of steroidogenic enzyme genes via the suppression of Nur77 transactivation. ERα physically interacted with Nur77 and inhibited its DNA binding activity. In addition, ERα/E2 signaling decreased Nur77 protein levels. Consistent with the above results, the testicular testosterone level was higher in Leydig cell-specific ERα knock-out mice (ERα(flox/flox)Cyp17iCre) than in wild-type mice (ERα(flox/flox)). Taken together, these results suggest that ERα/E2 signaling controls the Nur77-mediated expression of steroidogenic enzyme genes in Leydig cells. These findings may provide a mechanistic explanation for the local regulation of testicular steroidogenesis by estrogenic compounds and ERα.

A common origin for the bacterial toxin-antitoxin systems parD and ccd, suggested by analyses of toxin/target and toxin/antitoxin interactions

Bacterial toxin-antitoxin (TA) systems encode two proteins, a potent inhibitor of cell proliferation (toxin) and its specific antidote (antitoxin). Structural data has revealed striking similarities between the two model TA toxins CcdB, a DNA gyrase inhibitor encoded by the ccd system of plasmid F, and Kid, a site-specific endoribonuclease encoded by the parD system of plasmid R1. While a common structural fold seemed at odds with the two clearly different modes of action of these toxins, the possibility of functional crosstalk between the parD and ccd systems, which would further point to their common evolutionary origin, has not been documented. Here, we show that the cleavage of RNA and the inhibition of protein synthesis by the Kid toxin, two activities that are specifically counteracted by its cognate Kis antitoxin, are altered, but not inhibited, by the CcdA antitoxin. In addition, Kis was able to inhibit the stimulation of DNA gyrase-mediated cleavage of DNA by CcdB, albeit less efficiently than CcdA. We further show that physical interactions between the toxins and antitoxins of the different systems do occur and define the stoichiometry of the complexes formed. We found that CcdB did not degrade RNA nor did Kid have any reproducible effect on the tested DNA gyrase activities, suggesting that these toxins evolved to reach different, rather than common, cellular targets.

Viral transgene expression delivered by repeat intraocular adenoviral vector injection: in vivo live imaging study

We delivered adenovirus vector (Ad) via intravitreous injection and monitored transgene (luciferase) expression in living mice (BALB/c) at multiple time points. In vivo live imaging technology was able to assess dynamically intraocular luciferase expression in a single animal population throughout the entire experiment period. Using this information, we were able to determine the optimal time point for readministration of Ad into the eyes and to dynamically study the time course of expression of a second Ad administration. Optical imaging demonstrated the limited period of transgene expression in eyes. Significant transgene signal was also detected in livers. The repeat intraocular delivery of the adenovirus resulted in significant blunting of transgene expression in both eyes and livers compared to the initial delivery. Periocular corticosteroid (triamcinolone acetonide) injection combined with initial Ad delivery was effective to rescue luciferase expression on repeat Ad vector delivery. However, this effect was not observed when corticosteroid was combined with repeat Ad delivery. Although corticosteroid enhanced ocular transgene expression, it also increased transgene expression in liver, which has potential safety implications. This dynamic transgene expression in eyes was successfully traced and monitored via a live imaging technique.

NADPH oxidase subunit 4 mediates cycling hypoxia-promoted radiation resistance in glioblastoma multiforme

Cycling hypoxia is a well-recognized phenomenon within animal and human solid tumors. It mediates tumor progression and radiotherapy resistance through mechanisms that involve reactive oxygen species (ROS) production. However, details of the mechanism underlying cycling hypoxia-mediated radioresistance remain obscure. We have previously shown that in glioblastoma, NADPH oxidase subunit 4 (Nox4) is a critical mediator involved in cycling hypoxia-mediated ROS production and tumor progression. Here, we examined the impact of an in vivo tumor microenvironment on Nox4 expression pattern and its impact on radiosensitivity in GBM8401 and U251, two glioblastoma cell lines stably transfected with a dual hypoxia-inducible factor-1 (HIF-1) signaling reporter construct. Furthermore, in order to isolate hypoxic tumor cell subpopulations from human glioblastoma xenografts based on the physiological and molecular characteristics of tumor hypoxia, several techniques were utilized. In this study, the perfusion marker Hoechst 33342 staining and HIF-1 activation labeling were used together with immunofluorescence imaging and fluorescence-activated cell sorting (FACS). Our results revealed that Nox4 was predominantly highly expressed in the endogenous cycling hypoxic areas with HIF-1 activation and blood perfusion within the solid tumor microenvironment. Moreover, when compared to the normoxic or chronic hypoxic cells, the cycling hypoxic tumor cells derived from glioblastoma xenografts have much higher Nox4 expression, ROS levels, and radioresistance. Nox4 suppression in intracerebral glioblastoma-bearing mice suppressed tumor microenvironment-mediated radioresistance and enhanced the efficiency of radiotherapy. In summary, our findings indicated that cycling hypoxia-induced Nox4 plays an important role in tumor microenvironment-promoted radioresistance in glioblastoma; hence, targeting Nox4 may be an attractive therapeutic strategy for blocking cycling hypoxia-mediated radioresistance.

Efficacy of sequential treatment with sunitinib-everolimus in an orthotopic mouse model of renal cell carcinoma

BACKGROUND/AIM

Sequential treatment with targeted agents is standard of care for patients with metastatic renal cell carcinoma (mRCC). However, clinical data directly comparing treatment outcomes with a mammalian target of rapamycin inhibitor or a vascular endothelial growth factor-targeted agent in the second-line setting are lacking. We evaluated sequential treatment in a syngeneic, orthotopic mouse model of mRCC.

MATERIALS AND METHODS

BALB/c mice were orthotopically implanted with murine RCC (RENCA) cells expressing luciferase and randomized to vehicle, sunitinib, sunitinib followed by sorafenib, or sunitinib followed by everolimus. Tumor growth and metastases were assessed by in vivo (whole body) and ex vivo (primary tumor, lung, liver) luciferase activity and necropsies, performed on day 20 or 46 for vehicle and treatment groups, respectively.

RESULTS

Sunitinib followed by everolimus was associated with reduced luciferase activity and primary tumor weight and volume compared with sunitinib, and sunitinib followed by sorafenib.

CONCLUSION

Sequential therapy with sunitinib followed by everolimus demonstrated significant antitumor and anti-metastatic effects.

Induction, modulation and potential targets of miR-210 in pancreatic cancer cells

BACKGROUND

MiR-210 is induced by hypoxia and plays different roles in the development of certain cancers. However, little is known about its role in pancreatic cancer (PC). This study aimed to explore the induction and modulation of PC by miR-210 and its potential molecular targets.

METHODS

PC cells were cultured under normoxic and hypoxic conditions. Expression of miR-210 and hypoxia-inducible factor (HIF)-1alpha was detected using quantitative reverse-transcription polymerase chain reaction. Cancer cells were transiently transfected with HIF-1alpha small interfering RNA (siRNA) and miR-210 mimics, and cell proliferation was measured using the CCK-8 assay. Potential targets for miR-210 were then identified using a dual luciferase reporter assay.

RESULTS

Hypoxic conditions induced miR-210 expression in six PC cell lines (AsPC-1, BxPC-3, MIAPaCa-2, PANC-1, Su86.86 and SW1990), but not in Capan-1 or T3M4 cells. Transfection of HIF-1alpha siRNA into PANC-1 cells markedly inhibited HIF-1alpha expression, and subsequently down-regulated miR-210 expression under hypoxic conditions. MiR-210 had no observable impact on the proliferation of PANC-1 or Su86.86 cells and dual luciferase reporter assays showed significantly reduced luciferase activity in the wild-type E2F3, EFNA3, GIT2, MNT, ZNF462 and EGR3 constructs, compared to the corresponding mutants, but not in HOXA3.

CONCLUSIONS

These results suggest that miR-210 expression in PC cells is induced by hypoxia through a HIF-1alpha-dependent pathway, but does not influence PC cell proliferation. Also, E2F3, EFNA3, GIT2, MNT, ZNF462 and EGR3 may be potential miR-210 targets in PC.

[Expression of thermostable recombiant Luciola lateralis luciferase and development of heat-stable pyrosequencing system]

Pyrosequencing is a tool based on bioluminescence reaction for real-time analyzing DNA sequences. The sensitivity of pyrosequencing mainly depends on luciferase in reaction mixture. However, the instability of pyrosequencing reagents caused by fragile wild Photinus pyralis luciferase (PpL) in conventional pyrosequencing usually leads to unsatisfied results, which limits the application of pyrosequencing. In order to improve the stability of pyrosequencing reagents, the coding sequences of mutant thermostable Luciola lateralis luciferase (rt-LlL) was synthesized, and inserted into the plasmid of pET28a(+) to express the thermostable rt-LlL with a 6 x His-tag in the N terminal. The purified rt-LlL with the molecular mass of 60 kDa was obtained by Ni-affinity chromatography. The specific activity of rt-LlL was determined as 4.29 x 10(10) RLU/mg. Moreover, the thermostability of rt-LlL was investigated, and the results showed that rt-LlL had activity at 50 degrees C, and remained 90% of activity after incubated at 40 degrees C for 25 min. Finally, rt-LlL was used to substitute commercial Photinus pyralis luciferase in conventional pyrosequencing reagent to get thermostable pyrosequencing reagent. Comparing with conventional pyrosequencing reagent, the thermostable pyrosequencing reagent is more stable, and it's activity would not lose when incubated at 37 degrees C for 1 h. This study laid foundation of establishing reliable and stable pyrosequencing system which would be applied in Point-of-Care Testing.

A real time Metridia luciferase based non-invasive reporter assay of mammalian cell viability and cytotoxicity via the β-actin promoter and enhancer

Secreted reporter molecules offer a means to evaluate biological processes in real time without the need to sacrifice samples at pre-determined endpoints. Here we have adapted the secreted bioluminescent reporter gene, Metridia luciferase, for use in a real-time viability assay for mammalian cells. The coding region of the marine copepod gene has been codon optimized for expression in human cells (hMLuc) and placed under the control of the human β-actin promoter and enhancer. Metridia luciferase activity of stably transfected cell models corresponded linearly with cell number over a 4-log dynamic range, detecting as few as 40 cells. When compared to standard endpoint viability assays, which measure the mitochondrial dehydrogenase reduction of tetrazolium salts, the hMLuc viability assay had a broader linear range of detection, was applicable to large tissue culture vessels, and allowed the same sample to be repeatedly measured over several days. Additional studies confirmed that MLuc activity was inhibited by serum, but demonstrated that assay activity remained linear and was measurable in the serum of mice bearing subcutaneous hMLuc-expressing tumors. In summary, these comparative studies demonstrate the value of humanized Metridia luciferase as an inexpensive and non-invasive method for analyzing viable cell number, growth, tumor volume, and therapeutic response in real time.

On-bead expression of recombinant proteins in an agarose gel matrix coated on a glass slide

A system for expression and in situ display of recombinant proteins on a microbead surface is described. Biotinylated PCR products were immobilized on microbead surfaces, which were then embedded in a gel matrix and supplied with translation machinery and substrates. Upon the incubation of the gel matrix, target proteins encoded on the bead-immobilized DNA were expressed and captured on the same bead, thus allowing bead-mediated linkage of DNA and encoded proteins. The new method combines the simplicity and convenience of solid-phase separation of genetic information with the benefits of cell-free protein synthesis, such as instant translation of genetic information, unrestricted substrate accessibility and flexible assay configuration design.

Genome-wide identification of polycomb target genes reveals a functional association of Pho with Scm in Bombyx mori

Polycomb group (PcG) proteins are evolutionarily conserved chromatin modifiers and act together in three multimeric complexes, Polycomb repressive complex 1 (PRC1), Polycomb repressive complex 2 (PRC2), and Pleiohomeotic repressive complex (PhoRC), to repress transcription of the target genes. Here, we identified Polycomb target genes in Bombyx mori with holocentric centromere using genome-wide expression screening based on the knockdown of BmSCE, BmESC, BmPHO, or BmSCM gene, which represent the distinct complexes. As a result, the expressions of 29 genes were up-regulated after knocking down 4 PcG genes. Particularly, there is a significant overlap between targets of BmPho (331 out of 524) and BmScm (331 out of 532), and among these, 190 genes function as regulator factors playing important roles in development. We also found that BmPho, as well as BmScm, can interact with other Polycomb components examined in this study. Further detailed analysis revealed that the C-terminus of BmPho containing zinc finger domain is involved in the interaction between BmPho and BmScm. Moreover, the zinc finger domain in BmPho contributes to its inhibitory function and ectopic overexpression of BmScm is able to promote transcriptional repression by Gal4-Pho fusions including BmScm-interacting domain. Loss of BmPho expression causes relocalization of BmScm into the cytoplasm. Collectively, we provide evidence of a functional link between BmPho and BmScm, and propose two Polycomb-related repression mechanisms requiring only BmPho associated with BmScm or a whole set of PcG complexes.

Structural insights into TIR domain specificity of the bridging adaptor Mal in TLR4 signaling

MyD88 adaptor-like protein (Mal) is a crucial adaptor that acts as a bridge to recruit the MyD88 molecule to activated TLR4 receptors in response to invading pathogens. The specific assembly of the Toll/interleukin-1 receptor (TIR) domains of TLR4, Mal and MyD88 is responsible for proper signal transduction in the TLR4 signaling pathway. However, the molecular mechanism for the specificity of these TIR domains remains unclear. Here, we present the crystal structure of the TIR domain of the human Mal molecule (Mal-TIR) at a resolution of 2.4 Å. Unexpectedly, Mal-TIR exhibits an extraordinarily long AB loop, but no αB helix or BB loop, distinguishing it from other TIR domains. More importantly, the Mal-TIR AB loop is capable of mediating direct binding to the TIR domains of TLR4 and MyD88 simultaneously. We also found that Mal-TIR can form a back-to-back dimer that may resemble the dimeric assembly of the entire Mal molecule. Our data demonstrate the bridge role of the Mal-TIR domain and provide important information about TIR domain specificity.

Histone H2B ubiquitin ligases RNF20 and RNF40 in androgen signaling and prostate cancer cell growth

Since data-mining from the Oncomine database revealed that expression of histone H2B K120 monoubiquitin (H2Bub1) ligase RNF20 is decreased in metastatic prostate cancer, we elucidated the effect of RNF20 and its homolog RNF40 on androgen receptor (AR)-dependent transcription and prostate cancer cell growth. Both RNF20 and RNF40 were able to functionally and physically interact with the AR and modulate its transcriptional activity in intact cells. Chromatin immunoprecipitation analyses showed that the androgen induction of FKBP51 and PSA in LNCaP prostate cancer cells is accompanied with a dynamic increase in the H2Bub1 within the transcribed regions of these loci. Interestingly, depletion of RNF20 or RNF40 strongly retarded the growth of LNCaP cells, which was however unlikely to be due to altered androgen signaling, but due to decreased expression of several cell cycle promoters. Collectively, our results suggest that RNF20 and RNF40, either via ubiquitylation of H2B or other targets, are coupled to the proliferation of prostate cancer cells.

Bone morphogenetic protein-3b (BMP-3b) inhibits osteoblast differentiation via Smad2/3 pathway by counteracting Smad1/5/8 signaling

Despite the involvement of BMP-3b (also called GDF-10) in osteogenesis, embryogenesis and adipogenesis, the functional receptors and intracellular signaling of BMP-3b have yet to be elucidated. In the present study, we investigated the cellular mechanism of BMP-3b in osteoblast differentiation using mouse myoblastic C2C12 cells. BMP-3b stimulated activin/TGF-β-responsive promoter activities. The stimulatory actions of BMP-3b on activin/TGF-β-responsive activities were suppressed by co-treatment with BMP-2. BMP-responsive promoter activities stimulated by BMP-2 were significantly inhibited by treatment with BMP-3b. BMP-3b suppressed the expression of osteoblastic markers including Runx2, osteocalcin and type-1 collagen induced by BMP-2, -4, -6 and -7. BMP-2-induced Smad1/5/8 phosphorylation and mRNA levels of the BMP target gene Id-1 were suppressed by co-treatment with BMP-3b, although BMP-3b failed to activate Smad1/5/8 signaling. Of interest, the BMP-3b suppression of BMP-2-induced Id-1 expression was not observed in cells overexpressing Smad4 molecules. On the other hand, BMP-3b directly activated Smad2/3 phosphorylation and activin/TGF-β target gene PAI-1 mRNA expression, while BMP-2 suppressed BMP-3b-induced Smad2/3 signal activation. BMP-2 inhibition of BMP-3b-induced PAI-1 expression was also reversed by overexpression of Smad4. Analysis using inhibitors for BMP-Smad1/5/8 pathways revealed that these BMP-3b effects were mediated via receptors other than ALK-2, -3 and -6. Furthermore, results of inhibitory studies using extracellular domains for BMP receptor constructs showed that the activity of BMP-3b was functionally facilitated by a combination of ALK-4 and ActRIIA. Collectively, BMP-3b plays an inhibitory role in the process of osteoblast differentiation, in which BMP-3b and BMP-2 are mutually antagonistic possibly by competing with the availability of Smad4.

Histone deacetylase inhibition activates transcription factor Nrf2 and protects against cerebral ischemic damage

Interest in histone deacetylase (HDAC)-based therapeutics as a potential treatment for stroke has grown dramatically. The neuroprotection of HDAC inhibition may involve multiple mechanisms, including modulation of transcription factor acetylation independent of histones. The transcription factor Nrf2 has been shown to be protective in stroke as a key regulator of antioxidant-responsive genes. Here, we hypothesized that HDAC inhibition might provide neuroprotection against mouse cerebral ischemia by activating the Nrf2 pathway. We determined that the classic HDAC inhibitor trichostatin A increased neuronal cell viability after oxygen-glucose deprivation (from an OD value of 0.10±0.01 to 0.25±0.08) and reduced infarct volume in wild-type mice with stroke (from 49.1±3.8 to 21.3±4.6%). In vitro studies showed that HDAC inhibition reduced Nrf2 suppressor Keap1 expression, induced Keap1/Nrf2 dissociation, Nrf2 nuclear translocation, and Nrf2 binding to antioxidant response elements in heme oxygenase 1 (HO1), and caused HO1 transcription. Furthermore, we demonstrated that HDAC inhibition upregulated proteins downstream of Nrf2, including HO1, NAD(P)H:quinone oxidoreductase 1, and glutamate-cysteine ligase catalytic subunit in neuron cultures and brain tissue. Finally, unlike wild-type mice, Nrf2-deficient mice were not protected by pharmacologic inhibition of HDAC after cerebral ischemia. Our studies suggest that activation of Nrf2 might be an important mechanism by which HDAC inhibition provides neuroprotection.

Fhl1 as a downstream target of Wnt signaling to promote myogenesis of C2C12 cells

Previous studies have shown that Wnt signaling is involved in postnatal mammalian myogenesis; however, the downstream mechanism of Wnt signaling is not fully understood. This study reports that the murine four-and-a-half LIM domain 1 (Fhl1) could be stimulated by β-catenin or LiCl treatment to induce myogenesis. In contrast, knockdown of the Fhl1 gene expression in C2C12 cells led to reduced myotube formation. We also adopted reporter assays to demonstrate that either β-catenin or LiCl significantly activated the Fhl1 promoter, which contains four putative consensus TCF/LEF binding sites. Mutations of two of these sites caused a significant decrease in promoter activity by luciferase reporter assay. Thus, we suggest that Wnt signaling induces muscle cell differentiation, at least partly, through Fhl1 activation.

Sulforaphane attenuates hepatic fibrosis via NF-E2-related factor 2-mediated inhibition of transforming growth factor-β/Smad signaling

Sulforaphane (SFN) is a dietary isothiocyanate that exerts chemopreventive effects via NF-E2-related factor 2 (Nrf2)-mediated induction of antioxidant/phase II enzymes, such as heme oxygenase-1 (HO-1) and NAD(P)H quinone oxidoreductase 1 (NQO1). This work was undertaken to evaluate the effects of SFN on hepatic fibrosis and profibrotic transforming growth factor (TGF)-β/Smad signaling, which are closely associated with oxidative stress. SFN suppressed TGF-β-enhanced expression of α-smooth muscle actin (α-SMA), a marker of hepatic stellate cell (HSC) activation, and profibrogenic genes such as type I collagen, fibronectin, tissue inhibitor of matrix metalloproteinase (TIMP)-1, and plasminogen activator inhibitor (PAI)-1 in hTERT, an immortalized human HSC line. SFN inhibited TGF-β-stimulated activity of a PAI-1 promoter construct and (CAGA)(9) MLP-Luc, an artificial Smad3/4-specific reporter, in addition to reducing phosphorylation and nuclear translocation of Smad3. Nrf2 overexpression was sufficient to inhibit the TGF-β/Smad signaling and PAI-1 expression. Conversely, knockdown of Nrf2, but not inhibition of HO-1 or NQO1 activity, significantly abolished the inhibitory effect of SFN on (CAGA)(9) MLP-Luc activity. However, inhibition of NQO1 activity reversed repression of TGF-β-stimulated expression of type I collagen by SFN, suggesting the involvement of antioxidant activity of SFN in the suppression of Smad-independent fibrogenic gene expression. Finally, SFN treatment attenuated the development and progression of early stage hepatic fibrosis induced by bile duct ligation in mice, accompanied by reduced expression of type I collagen and α-SMA. Collectively, these results show that SFN elicits an antifibrotic effect on hepatic fibrosis through Nrf2-mediated inhibition of the TGF-β/Smad signaling and subsequent suppression of HSC activation and fibrogenic gene expression.