Transgenic mouse model harboring the transcriptional fusion ccl20-luciferase as a novel reporter of pro-inflammatory response

The chemokine CCL20, the unique ligand of CCR6 functions as an attractant of immune cells. Expression of CCL20 is induced by Toll-like Receptor (TLR) signaling or proinflammatory cytokine stimulation. However CCL20 is also constitutively produced at specific epithelial sites of mucosa. This expression profile is achieved by transcriptional regulation. In the present work we characterized regulatory features of mouse Ccl20 gene. Transcriptional fusions between the mouse Ccl20 promoter and the firefly luciferase (luc) encoding gene were constructed and assessed in in vitro and in vivo assays. We found that liver CCL20 expression and luciferase activity were upregulated by systemic administration of the TLR5 agonist flagellin. Using shRNA and dominant negative form specific for mouse TLR5, we showed that this expression was controlled by TLR5. To address in situ the regulation of gene activity, a transgenic mouse line harboring a functional Ccl20-luc fusion was generated. The luciferase expression was highly concordant with Ccl20 expression in different tissues. Our data indicate that the transgenic mouse model can be used to monitor activation of innate response in vivo.

NanoLuc reporter for dual luciferase imaging in living animals

Bioluminescence imaging is widely used for cell-based assays and animal imaging studies in biomedical research and drug development, capitalizing on the high signal to background of this technique. A relatively small number of luciferases are available for imaging studies, substantially limiting the ability to image multiple molecular and cellular events, as done commonly with fluorescence imaging. To advance dual reporter bioluminescence molecular imaging, we tested a recently developed, adenosine triphosphate–independent luciferase enzyme from Oplophorus gracilirostris (NanoLuc [NL]) as a reporter for animal imaging. We demonstrated that NL could be imaged in superficial and deep tissues in living mice, although the detection of NL in deep tissues was limited by emission of predominantly blue light by this enzyme. Changes in bioluminescence from NL over time could be used to quantify tumor growth, and secreted NL was detectable in small volumes of serum. We combined NL and firefly luciferase reporters to quantify two key steps in transforming growth factor β signaling in intact cells and living mice, establishing a novel dual luciferase imaging strategy for quantifying signal transduction and drug targeting. Our results establish NL as a new reporter for bioluminescence imaging studies in intact cells and living mice that will expand imaging of signal transduction in normal physiology, disease, and drug development.

Design and application of an internal amplification control to improve Dehalococcoides mccartyi 16S rRNA gene enumeration by qPCR

Dehalococcoides mccartyi (Dhc) strains are keystone bacteria for reductive dechlorination of chlorinated ethenes to nontoxic ethene in contaminated aquifers. Enumeration of Dhc biomarker genes using quantitative real-time PCR (qPCR) in groundwater is a key component of site assessment and bioremediation monitoring. Unfortunately, standardized qPCR procedures that recognize impaired measurements due to PCR inhibition, low template DNA concentrations, or analytical error are not available, thus limiting confidence in qPCR data. To improve contemporary approaches for enumerating Dhc in environmental samples, multiplex qPCR assays were designed to quantify the Dhc 16S rRNA gene and one of two different internal amplification controls (IACs): a modified Dhc 16S rRNA gene fragment (Dhc*) and the firefly luciferase gene luc. The Dhc* IAC exhibited competitive inhibition in qPCR with the Dhc 16S rRNA gene template when the ratio of either target was 100-fold greater than the other target. A multiplex qPCR assay with the luc IAC avoided competitive inhibition and accurately quantified Dhc abundances ranging from ∼10 to 10(7) 16S rRNA gene copies per reaction. The addition of ∼10(6) E. coli luc IAC to simulated groundwater amended with the Dhc-containing consortium KB-1 yielded reproducible luc counts after DNA extraction and multiplex qPCR enumeration. The application of the luc IAC assay improved Dhc biomarker gene quantification from simulated groundwater samples and is a valuable approach for "ground truthing" qPCR data obtained in different laboratories, thus reducing ambiguity associated with qPCR enumeration and reproducibility.

A novel cationic microbubble coated with stearic acid-modified polyethylenimine to enhance DNA loading and gene delivery by ultrasound

A novel cationic microbubble (MB) for improvement of the DNA loading capacity and the ultrasound-mediated gene delivery efficiency has been developed; it has been prepared with commercial lipids and a stearic acid modified polyethylenimine 600 (Stearic-PEI600) polymer synthesized via acylation reaction of branched PEI600 and stearic acid mediated by N, N'-carbonyldiimidazole (CDI). The MBs’ concentration, size distribution, stability and zeta potential (ζ-potential) were measured and the DNA loading capacity was examined as a function of the amount of Stearic-PEI600. The gene transfection efficiency and cytotoxicity were also examined using breast cancer MCF-7 cells via the reporter plasmid pCMV-Luc, encoding the firefly luciferase gene. The results showed that the Stearic-PEI600 polymer caused a significant increase in magnitude of ζ-potential of MBs. The addition of DNA into cationic MBs can shift ζ-potentials from positive to negative values. The DNA loading capacity of the MBs grew linearly from (5±0.2) ×10⁻³ pg/µm² to (20±1.8) ×10⁻³ pg/µm² when Stearic-PEI600 was increased from 5 mol% to 30 mol%. Transfection of MCF-7 cells using 5% PEI600 MBs plus ultrasound exposure yielded 5.76±2.58×10³ p/s/cm²/sr average radiance intensity, was 8.97- and 7.53-fold higher than those treated with plain MBs plus ultrasound (6.41±5.82) ×10² p/s/cm²/sr, (P<0.01) and PEI600 MBs without ultrasound (7.65±6.18) ×10² p/s/cm²/sr, (P<0.01), respectively. However, the PEI600 MBs showed slightly higher cytotoxicity than plain MBs. The cells treated with PEI600-MBs and plain MBs plus ultrasound showed 59.5±6.1% and 71.4±7.1% cell viability, respectively. In conclusion, our study demonstrated that the novel cationic MBs were able to increase DNA loading capacity and gene transfection efficiency and could be potentially applied in targeted gene delivery and therapy.

Determination of PCDD/Fs, PBDD/Fs and dioxin-like PCBs in human milk from mothers residing in the rural areas in Flanders, using the CALUX bioassay and GC-HRMS

Since the CALUX (Chemically Activated LUciferase gene eXpression) bioassay is a fast and inexpensive tool for the determination of dioxin-like compounds in a large number of samples and requires only small sample volumes, the use of this technique in human biomonitoring programs provides a good alternative to GC-HRMS. In this study, a new CALUX method for the separate analysis of PCDD/Fs and dioxin-like PCBs (dl-PCBs) in small amounts of human milk samples with the new sensitive H1L7.5c1 cell line was used to analyze 84 human milk samples, collected from mothers residing in the Flemish rural communities. The geometric mean CALUX-Bioanalytical Equivalent (CALUX-BEQ) values, reported for the 84 mothers from the study area were 10.4 (95% CI: 9.4-11.4) pg CALUX-BEQ per gram lipid or 0.41 (95% CI: 0.37-0.45) pg CALUX-BEQ per gram milk for the PCDD/Fs and 1.73 (1.57-1.91) pg CALUX-BEQ per gram lipid or 0.07 (95% CI: 0.06-0.08) pg CALUX-BEQ per gram milk for the dioxin-like PCBs. Multiple regression analysis showed significant associations between PCDD/Fs and weight change after pregnancy, smoking and consumption of local eggs. One pooled human milk sample was analyzed with both CALUX and GC-HRMS. The ratio of CALUX and GC-HRMS results for this sample were respectively 1.60, 0.58 and 1.23 for the PCDD/Fs, the dl-PCBs and the sum of both fractions, when using the 2005-TEF values. Additionally, also low levels of certain brominated dioxins and furans were detected in the pooled sample with GC-HRMS.

Dissecting non-coding RNA mechanisms in cellulo by Single-molecule High-Resolution Localization and Counting

Non-coding RNAs (ncRNAs) recently were discovered to outnumber their protein-coding counterparts, yet their diverse functions are still poorly understood. Here we report on a method for the intracellular Single-molecule High-Resolution Localization and Counting (iSHiRLoC) of microRNAs (miRNAs), a conserved, ubiquitous class of regulatory ncRNAs that controls the expression of over 60% of all mammalian protein coding genes post-transcriptionally, by a mechanism shrouded by seemingly contradictory observations. We present protocols to execute single particle tracking (SPT) and single-molecule counting of functional microinjected, fluorophore-labeled miRNAs and thereby extract diffusion coefficients and molecular stoichiometries of micro-ribonucleoprotein (miRNP) complexes from living and fixed cells, respectively. This probing of miRNAs at the single molecule level sheds new light on the intracellular assembly/disassembly of miRNPs, thus beginning to unravel the dynamic nature of this important gene regulatory pathway and facilitating the development of a parsimonious model for their obscured mechanism of action.

Differential post-surgical metastasis and survival in SCID, NOD-SCID and NOD-SCID-IL-2Rγ(null) mice with parental and subline variants of human breast cancer: implications for host defense mechanisms regulating metastasis

We compare for the first time, the metastatic aggressiveness of the parental MDA-MB-231 breast cancer cell line and two luciferase-tagged in vivo-derived and selected pro-metastatic variants (LM2-4/luc⁺ and 164/8-1B/luc⁺) in SCID, NOD-SCID and NOD-SCID-IL-2Rγ^null (NSG) mice following orthotopic implantation and primary tumour resection. The variants are known to be more aggressively metastatic in SCID mice, compared to the parental line which has limited spontaneous metastatic competence in these mice. When 2×10⁶ cells were injected into the mammary fat pad, the growth of the resultant primary tumours was identical for the various cell lines in the three strains of mice. However, metastatic spread of all three cell lines, including the MDA-MB-231 parental cell line, was strikingly more aggressive in the highly immunocompromised NSG mice compared to both NOD-SCID and SCID mice, resulting in extensive multi-organ metastases and a significant reduction in overall survival. While these studies were facilitated by monitoring post-surgical spontaneous metastases using whole body bioluminescence imaging, we observed that the luciferase-tagged parental line showed altered growth and diminished metastatic properties compared to its untagged counterpart. Our results are the first to show that host immunity can have a profound impact on the spread of spontaneous visceral metastases and survival following resection of a primary tumour in circumstances where the growth of primary tumours is not similarly affected; as such they highlight the importance of immunity in the metastatic process, and by extension, suggest certain therapeutic strategies that may have a significant impact on reducing metastasis.

Visualising androgen receptor activity in male and female mice

Androgens, required for normal development and fertility of males and females, have vital roles in the reproductive tract, brain, cardiovascular system, smooth muscle and bone. Androgens function via the androgen receptor (AR), a ligand-dependent transcription factor. To assay and localise AR activity in vivo we generated the transgenic “ARE-Luc” mouse, expressing a luciferase reporter gene under the control of activated endogenous AR. In vivo imaging of androgen-mediated luciferase activity revealed several strongly expressing tissues in the male mouse as expected and also in certain female tissues. In males the testes, prostate, seminal vesicles and bone marrow all showed high AR activity. In females, strong activity was seen in the ovaries, uterus, omentum tissue and mammary glands. In both sexes AR expression and activity was also found in salivary glands, the eye (and associated glands), adipose tissue, spleen and, notably, regions of the brain. Luciferase protein expression was found in the same cell layers as androgen receptor expression. Additionally, mouse AR expression and activity correlated well with AR expression in human tissues. The anti-androgen bicalutamide reduced luciferase signal in all tissues. Our model demonstrates that androgens can act in these tissues directly via AR, rather than exclusively via androgen aromatisation to estrogens and activation of the estrogen receptor. Additionally, it visually demonstrates the fundamental importance of AR signalling outside the normal role in the reproductive organs. This model represents an important tool for physiological and developmental analysis of androgen signalling, and for characterization of known and novel androgenic or antiandrogenic compounds.

Real-time tracking of adipose tissue-derived stem cells with injectable scaffolds in the infarcted heart

Adipose tissue-derived stem cells (ADSCs) has shown promise in the emerging field of regenerative medicine. Many studies have highlighted the importance of coadministering a "scaffold" for increasing intramyocardial retention of stem cells. In this work, an optimized method was developed for efficient transduction of ADSCs with a lentiviral vector carrying a triple-fusion reporter gene that consists of firefly luciferase, monomeric red fluorescence protein, and truncated thymidine kinase (fluc-mrfp-ttk). The transduced ADSCs were assessed on biological performance and transplanted into infarcted heart with fibrin scaffolds. In vivo cell retention was tracked by bioluminescence imaging (BLI) and micro positron emission tomography/computed tomography (PET/CT) imaging. Histological assessment was performed for regeneration potentials. The results showed that lentiviral transduction did not influence cell functions. In vitro imaging analysis showed a robust linear correlation between cell numbers and BLI signals (R (2) = 0.99) as well as between cell numbers and radiotracer uptakes (R (2) = 0.98). Transduced ADSCs were visualized in the heart under both BLI and PET/CT imaging, contributing to cardiomyocyte regeneration and angiogenesis in the implanted areas. Compared with BLI monitoring, PET/CT data provided precise localization for cell retention. Thus, a combination of imaging modalities can assist in reliable and efficient monitoring of transplanted cells, holding great potential for the transplantation of injectable scaffolds encapsulating stem cells in treating heart disease.

Development of a preclinical therapeutic model of human brain metastasis with chemoradiotherapy

Currently, survival of breast cancer patients with brain metastasis ranges from 2 to 16 months. In experimental brain metastasis studies, only 10% of lesions with the highest permeability exhibited cytotoxic responses to paclitaxel or doxorubicin. Therefore, radiation is the most frequently used treatment, and sensitizing agents, which synergize with radiation, can improve the efficacy of the therapy. In this study we used 435-Br1 cells containing the fluorescent protein (eGFP) gene and the photinus luciferase (PLuc) gene to develop a new brain metastatic cell model in mice through five in vivo/in vitro rounds. BR-eGFP-CMV/Luc-V5 brain metastatic cells induce parenchymal brain metastasis within 60.8 ± 13.8 days of intracarotid injection in all mice. We used this model to standardize a preclinical chemoradiotherapy protocol comprising three 5.5 Gy fractions delivered on consecutive days (overall dose of 16.5 Gy) which improved survival with regard to controls (60.29 ± 8.65 vs. 47.20 ± 11.14). Moreover, the combination of radiotherapy with temozolomide, 60 mg/Kg/day orally for five consecutive days doubled survival time of the mice 121.56 ± 52.53 days (Kaplan-Meier Curve, p < 0.001). This new preclinical chemoradiotherapy protocol proved useful for the study of radiation response/resistance in brain metastasis, either alone or in combination with new sensitizing agents.

Molecular imaging of expression of vascular endothelial growth factor a (VEGF a) in femoral bone grafts transplanted into living mice

The biology of cells transplanted with bone grafts is incompletely understood. Focusing on the early angiogenic response postgrafting, we report a mouse femur graft model in which grafts were derived from mice transgenic for a firefly luciferase (FLuc) bioluminescence reporter gene driven by a promoter for the angiogenic signaling molecule vascular endothelial growth factor (VEGF). Upon transplantation into wild-type (wt) mice, in vivo bioluminescence imaging (BLI) permitted longitudinal visualization and measurements of VEGF promoter activity in the transplanted graft cells and demonstrated a lag period of 7 days posttransplantation prior to robust induction of the promoter. To determine cellular mediators of VEGF induction in graft bone, primary graft-derived osteoblastic cells (GDOsts) were characterized. In vitro BLI on GDOsts showed hypoxia-induced VEGF expression and that this induction depended on PI3K signaling and, to a lesser degree, on the MEK pathway. This transcriptional regulation correlated with VEGF protein production and was validated in GDOsts seeded on demineralized bone matrix (DBM), a bone graft substitute material. Together, combined imaging of VEGF expression in living animals and in live cells provided clues about the regulation of VEGF in cells post-bone grafting. These data are particularly significant toward the development of future smart bone graft substitutes.

A mouse model for studying the clearance of hepatitis B virus in vivo using a luciferase reporter

Hepatitis B virus(HBV) infection remains a global problem, despite the effectiveness of the Hepatitis B vaccine in preventing infection. The resolution of Hepatitis B virus infection has been believed to be attributable to virus-specific immunity. In vivo direct evaluation of anti-HBV immunity in the liver is currently not possible. We have developed a new assay system that detects HBV clearance in the liver after the hydrodynamic transfer of a reporter gene and over-length, linear HBV DNA into hepatocytes, followed by bioluminescence imaging of the reporter gene (Fluc). We employed bioluminescence detection of luciferase expression in HBV-infected hepatocytes to measure the Hepatitis B core antigen (HBcAg)-specific immune responses directed against these infected hepatocytes. Only HBcAg-immunized, but not mock-treated, animals decreased the amounts of luciferase expression, HBsAg and viral DNA from the liver at day 28 after hydrodynamic infection with over-length HBV DNA, indicating that control of luciferase expression correlates with viral clearance from infected hepatocytes.

Efficiency of endovenous versus arterial administration of mesenchymal stem cells for ischemia-reperfusion-induced renal dysfunction in rats

BACKGROUND

Ischemia followed by reperfusion leads to acute renal failure in both native kidneys and a renal allograft. Our previous study found that transplantation of mesenchymal stem cells (MSCs) ameliorated ischemia-reperfusion (I/R)-induced kidney dysfunction by increasing the activities of antioxidant enzymes. The purpose of this study was to evaluate whether intra-arterial versus intravenous administration was more effective.

METHODS

Renal ischemia was induced by clamping the right renal vessels for 60 minutes after removal of the left kidney. MSCs (1 × 10(6)) were administered through either the tail vein (TV) or the renal arter (RA), followed by reperfusion. We evaluated kidney function as well as tissue activities of malondialdehyde (MDA), superoxide dismutase (SOD), and glutathione peroxidase (GSH-Px). Histopathologic and immunohistochemical examinations were performed. To tracking MSCs in vivo, they were transfected with firefly luciferase and monomeric red fluorescent protein reporter genes (fluc-mrfp). MSC retention and survival were assessed using bioluminescence imaging. We observed the effects of MSCs (1 × 10(6), 2 × 10(6), and 5 × 10(6)) on IR injury.

RESULTS

MSC infusion via either the tail vein or the renal artery significantly improved kidney function at days 1, 3, and 5 as indicated by lower urea and creatinine levels compared with vehicle controls (P < .05). I/R induced a reduction in renal tissue SOD activity but GSH-PX was significantly improved by MSCs (P < .05) on day 1. Treatment with MSCs also significantly reduced renal tissue MDA levels that had been otherwise increased by renal I/R injury (P < .05). The above parameters were similar between the TV and the RA groups. Histological examination revealed kidneys from MSC-treated rats to show fairly normal morphology. The percentages of proliferating cell nuclear antigen (PCNA)-positive cells were higher in the MSC groups: 16.83 ± 4.62%, 19.17 ± 6.21%, and 2.17 ± 1.16% for the TV, RA, and control groups, respectively. There was no significant dose-related difference among MSC groups. Bioluminescence imaging demonstrated most MSCs to be lost within 7 days after either intravenous or intra-arterial infusion.

CONCLUSIONS

MSCs ameliorated I/R-induced acute renal failure in rats with similar efficiency whether infused either through the TV or the RA. There was no dose-dependent responses.

Functional imaging of Rel expression in inflammatory processes using bioluminescence imaging system in transgenic mice

c-Rel plays important roles in many inflammatory diseases. Revealing the dynamic expression of c-Rel in disease processes in vivo is critical for understanding c-Rel functions and for developing anti-inflammatory drugs. In this paper, a transgenic mouse line, B6-Tg(c-Rel-luc)(Mlit), which incorporated the transgene firefly luciferase driven by a 14.5-kb fragment containing mouse c-Rel gene Rel promoter, was generated to monitor Rel expression in vivo. Luciferase expression could be tracked in living mice by the method of bioluminescence imaging in a variety of inflammatory processes, including LPS induced sepsis and EAE disease model. The luciferase expression in transgenic mice was comparable to the endogenous Rel expression and could be suppressed by administration of anti-inflammatory drug dexamethasone or aspirin. These results indicate that the B6-Tg(c-Rel-luc)(Mlit) mouse is a valuable animal model to study Rel expression in physiological and pathological processes, and the effects of various drug treatments in vivo.

Transient expression assays in tobacco protoplasts

The sequence information generated through genome and transcriptome analysis from plant tissues has reached unprecedented sizes. Sequence homology-based annotations may provide hints for the possible function and roles of particular plant genes, but the functional annotation remains nonexistent or incomplete for many of them. To discover gene functions, transient expression assays are a valuable tool because they can be done more rapidly and at a higher scale than generating stably transformed tissues. Here, we describe a transient expression assay in protoplasts derived from suspension cells of tobacco (Nicotiana tabacum) for the study of the transactivation capacities of transcription factors. To enhance throughput and reproducibility, this method can be automated, allowing medium-throughput screening of interactions between large compendia of potential transcription factors and gene promoters.

Luciferase assay to study the activity of a cloned promoter DNA fragment

Luciferase based assays have become an invaluable tool for the analysis of cloned promoter DNA fragments, both for verifying the ability of a potential promoter fragment to drive the expression of a luciferase reporter gene in various cellular contexts, and for dissecting binding elements in the promoter. Here, we describe the use of the Dual-Luciferase(®) Reporter Assay System created by Promega (Promega Corporation, Wisconsin, USA) to study the cloned 6.7 kilobases (kb) mouse (m) Tcf3 promoter DNA fragment in mouse embryonic derived neural stem cells (NSC). In this system, the expression of the firefly luciferase driven by the cloned mTcf3 promoter DNA fragment (including transcription initiation sites) is correlated with a co-transfected control reporter expressing Renilla luciferase from the herpes simplex virus (HSV) thymidine kinase promoter. Using an internal control reporter allows to normalize the activity of the experimental reporter to the internal control, which minimizes experimental variability.

Magnetic targeting of nanoparticles across the intact blood-brain barrier

Delivery of therapeutic or diagnostic agents across an intact blood-brain barrier (BBB) remains a major challenge. Here we demonstrate in a mouse model that magnetic nanoparticles (MNPs) can cross the normal BBB when subjected to an external magnetic field. Following a systemic administration, an applied external magnetic field mediates the ability of MNPs to permeate the BBB and accumulate in a perivascular zone of the brain parenchyma. Direct tracking and localization inside endothelial cells and in the perivascular extracellular matrix in vivo was established using fluorescent MNPs. These MNPs were inert and associated with low toxicity, using a non-invasive reporter for astrogliosis, biochemical and histological studies. Atomic force microscopy demonstrated that MNPs were internalized by endothelial cells, suggesting that trans-cellular trafficking may be a mechanism for the MNP crossing of the BBB observed. The silica-coated magnetic nanocapsules (SiMNCs) allow on-demand drug release via remote radio frequency (RF) magnetic field. Together, these results establish an effective strategy for regulating the biodistribution of MNPs in the brain through the application of an external magnetic field.

Corticotropin-releasing hormone regulates common target genes with divergent functions in corticotrope and neuronal cells

As a key regulator of the neuroendocrine stress axis and as a neuromodulator in the brain, the neuropeptide corticotropin-releasing hormone (CRH) plays an important role in various diseases of the central nervous system. Its cognate receptor CRH receptor type 1 (CRHR1) is a potential novel target for the therapeutic intervention in major depressive disorder. Therefore, a more precise understanding of involved intracellular signaling mechanisms is essential. The objective of this project was to identify specific target genes of CRHR1-mediated signaling pathways in the corticotrope cell line AtT-20 and in the neuronal cell line HN9 using microarray technology and qRT-PCR, respectively. In addition, we assessed the capacity of validated target genes to directly impact on CRHR1-dependent signaling using reporter assays. Thereby, we identified a set of CRHR1 downstream targets with diverging and cell type-specific roles which strengthen the role of CRH and CRHR1 as dynamic modulators of a variety of signal transduction mechanisms and cellular processes.

Safe genetic modification of cardiac stem cells using a site-specific integration technique

BACKGROUND

Human cardiac progenitor cells (hCPCs) are a promising cell source for regenerative repair after myocardial infarction. Exploitation of their full therapeutic potential may require stable genetic modification of the cells ex vivo. Safe genetic engineering of stem cells, using facile methods for site-specific integration of transgenes into known genomic contexts, would significantly enhance the overall safety and efficacy of cellular therapy in a variety of clinical contexts.

METHODS AND RESULTS

We used the phiC31 site-specific recombinase to achieve targeted integration of a triple fusion reporter gene into a known chromosomal context in hCPCs and human endothelial cells. Stable expression of the reporter gene from its unique chromosomal integration site resulted in no discernible genomic instability or adverse changes in cell phenotype. Namely, phiC31-modified hCPCs were unchanged in their differentiation propensity, cellular proliferative rate, and global gene expression profile when compared with unaltered control hCPCs. Expression of the triple fusion reporter gene enabled multimodal assessment of cell fate in vitro and in vivo using fluorescence microscopy, bioluminescence imaging, and positron emission tomography. Intramyocardial transplantation of genetically modified hCPCs resulted in significant improvement in myocardial function 2 weeks after cell delivery, as assessed by echocardiography (P=0.002) and MRI (P=0.001). We also demonstrated the feasibility and therapeutic efficacy of genetically modifying differentiated human endothelial cells, which enhanced hind limb perfusion (P<0.05 at day 7 and 14 after transplantation) on laser Doppler imaging.

CONCLUSIONS

The phiC31 integrase genomic modification system is a safe, efficient tool to enable site-specific integration of reporter transgenes in progenitor and differentiated cell types.

Antiandrogenic activity of humic substances

For long, natural organic matter (NOM) composed mainly of humic substances (HS) were regarded as inert in the ecosystems with respect to their possible chemical interaction with exposed organisms. However recently, NOM have been shown to elicit various adverse effects generally attributed to synthetic xenobiotics, including estrogenic effects translating into shifts of the gender ratios in populations. However, the anti/androgenic pathway was not yet evaluated. Here, we applied an anti/androgenic sensitive cell line MDA stably transfected with the firefly luciferase gene under transcriptional control of the androgen responsive element. With five out of twelve tested NOM preparations, particularly with soil and coal isolates, we identified a relatively high, concentration-dependent antiandrogenic effect. This appears to be the first study to show this endocrine disrupting pathway for a ubiquitous biogeochemical matrix, a potential activity which should not be neglected in forthcoming studies on synthetic endocrine disruptors in the environment.

Isolation, identification, and biological evaluation of Nrf2-ARE activator from the leaves of green perilla (Perilla frutescens var. crispa f. viridis)

The nuclear factor erythroid 2-related factor 2 (Nrf2)-antioxidant response element (ARE) pathway is a cellular defense system against oxidative stress. Activation of this pathway increases expression of antioxidant enzymes. Epidemiological studies have demonstrated that the consumption of fruits and vegetables is associated with reduced risk of contracting a variety of human diseases. The aim of this study is to find Nrf2-ARE activators in dietary fruits and vegetables. We first attempted to compare the potency of ARE activation in six fruit and six vegetables extracts. Green perilla (Perilla frutescens var. crispa f. viridis) extract exhibited high ARE activity. We isolated the active fraction from green perilla extract through bioactivity-guided fractionation. Based on nuclear magnetic resonance and mass spectrometric analysis, the active ingredient responsible for the ARE activity was identified as 2',3'-dihydroxy-4',6'-dimethoxychalcone (DDC). DDC induced the expression of antioxidant enzymes, such as γ-glutamylcysteine synthetase (γ-GCS), NAD(P)H: quinone oxidoreductase-1 (NQO1), and heme oxygenase-1. DDC inhibited the formation of intracellular reactive oxygen species and the cytotoxicity induced by 6-hydroxydopamine. Inhibition of the p38 mitogen-activated protein kinase pathway abolished ARE activation, the induction of γ-GCS and NQO1, and the cytoprotective effect brought about by DDC. Thus, this study demonstrated that DDC contained in green perilla enhanced cellular resistance to oxidative damage through activation of the Nrf2-ARE pathway.

Intracellular stability of 2'-OMe-4'-thioribonucleoside modified siRNA leads to long-term RNAi effect

Chemically modified siRNAs are expected to have resistance toward nuclease degradation and good thermal stability in duplex formation for in vivo applications. We have recently found that 2'-OMe-4'-thioRNA, a hybrid chemical modification based on 2'-OMeRNA and 4'-thioRNA, has high hybridization affinity for complementary RNA and significant resistance toward degradation in human plasma. These results prompted us to develop chemically modified siRNAs using 2'-OMe-4'-thioribonucleosides for therapeutic application. Effective modification patterns were screened with a luciferase reporter assay. The best modification pattern of siRNA, which conferred duration of the gene-silencing effect without loss of RNAi activity, was identified. Quantification of the remaining siRNA in HeLa-luc cells using a Heat-in-Triton (HIT) qRT-PCR revealed that the intracellular stability of the siRNA modified with 2'-OMe-4'-thioribonucleosides contributed significantly to the duration of its RNAi activity.

Development and characterization of a Pseudomonas aeruginosa in vitro coupled transcription-translation assay system for evaluation of translation inhibitors

Bacterial transcription and translation have proven to be effective targets for broad-spectrum antimicrobial therapies owing to the critical role they play in bacterial propagation and the overall conservation of the associated machinery involved. Escherichia coli is the most common source of S30 extract used in bacterial in vitro coupled transcription-translation assays, however, transcription-translation assays in other important pathogens including Staphylococcus aureus and Streptococcus pneumoniae have been described (Murray et al., 2001; Dandliker et al., 2003). Pseudomonas aeruginosa is an important and difficult-to-treat Gram-negative pathogen. In a drug discovery program, to de-risk any potential species specificity of novel inhibitors, we developed and optimized a robust method for the preparation of S30 extract from P. aeruginosa strain PAO1. Further, a P. aeruginosa transcription-translation assay using a firefly luciferase reporter plasmid was validated and compared to an E. coli S30-based system using a wide range of antibiotics encompassing multiple classes of translation inhibitors. Results showed a similar ranking of the activities of known inhibitors, illustrative of the high degree of conservation between the transcription-translation pathways in both organisms.

Functional variant in the autophagy-related 5 gene promotor is associated with childhood asthma

RATIONALE AND OBJECTIVE

Autophagy is a cellular process directed at eliminating or recycling cellular proteins. Recently, the autophagy pathway has been implicated in immune dysfunction, the pathogenesis of inflammatory disorders, and response to viral infection. Associations between two genes in the autophagy pathway, ATG5 and ATG7, with childhood asthma were investigated.

METHODS

Using genetic and experimental approaches, we examined the association of 13 HapMap-derived tagging SNPs in ATG5 and ATG7 with childhood asthma in 312 asthmatic and 246 non-allergic control children. We confirmed our findings by using independent cohorts and imputation analysis. Finally, we evaluated the functional relevance of a disease associated SNP.

MEASUREMENTS AND MAIN RESULTS

We demonstrated that ATG5 single nucleotide polymorphisms rs12201458 and rs510432 were associated with asthma (p = 0.00085 and 0.0025, respectively). In three independent cohorts, additional variants in ATG5 in the same LD block were associated with asthma (p<0.05). We found that rs510432 was functionally relevant and conferred significantly increased promotor activity. Furthermore, Atg5 expression was increased in nasal epithelium of acute asthmatics compared to stable asthmatics and non-asthmatic controls.

CONCLUSION

Genetic variants in ATG5, including a functional promotor variant, are associated with childhood asthma. These results provide novel evidence for a role for ATG5 in childhood asthma.

In vitro transfection of plasmid DNA by cationized gelatin prepared from different amine compounds

The objective of this paper is to compare the in vitro transfection efficiency of a luciferase plasmid DNA using cationized gelatin prepared from different amine compounds. The compounds used here were ethylenediamine, putrescine, spermidine and spermine, chemically introduced to the carboxyl group of gelatin for the cationization. Complexation of the cationized gelatin with the plasmid DNA was performed by simply mixing the two materials at various N+/P- mixing ratios (the molar number ratio of amino groups of gelatin to the phosphate groups of DNA) in aqueous solution. Gel retardation studies revealed that the formation of cationized-gelatin-plasmid DNA complexes depended on the N+/P- mixing ratio. The stronger interaction of plasmid DNA with the cationized gelatin of spermine compared to the other cationized gelatins was observed by an ethidium bromide intercalation assay and Scatchard binding analysis. When the transfection efficiency of plasmid DNA complexed with the various cationized gelatins at different N+/P- mixing ratios was evaluated for mouse L929 fibroblasts, the highest transfection efficiency was observed for the complex prepared from the cationized gelatin of spermine at a N+/P- mixing ratio of 2. The present study indicates that there is an optimal N+/P- mixing ratio and a type of amine compound or cationization extent of cationized gelatin to enhance the transfection efficiency of plasmid DNA.

A novel high-throughput vaccinia virus neutralization assay and preexisting immunity in populations from different geographic regions in China

Background

Pre-existing immunity to Vaccinia Tian Tan virus (VTT) resulting from a large vaccination campaign against smallpox prior to the early 1980s in China, has been a major issue for application of VTT-vector based vaccines. It is essential to establish a sensitive and high-throughput neutralization assay to understand the epidemiology of Vaccinia-specific immunity in current populations in China.

Methodology/Principal Findings

A new anti-Vaccinia virus (VACV) neutralization assay that used the attenuated replication-competent VTT carrying the firefly luciferase gene of Photinus pyralis (rTV-Fluc) was established and standardized for critical parameters that included the choice of cell line, viral infection dose, and the infection time. The current study evaluated the maintenance of virus-specific immunity after smallpox vaccination by conducting a non-randomized, cross-sectional analysis of antiviral antibody-mediated immune responses in volunteers examined 30–55 years after vaccination. The rTV-Fluc neutralization assay was able to detect neutralizing antibodies (NAbs) against Vaccinia virus without the ability to differentiate strains of Vaccinia virus. We showed that the neutralizing titers measured by our assay were similar to those obtained by the traditional plaque reduction neutralization test (PRNT). Using this assay, we found a low prevalence of NAb to VTT (7.6%) in individuals born before 1980 from Beijing and Anhui provinces in China, and when present, anti-VTT NAb titers were low. No NAbs were detected in all 222 samples from individuals born after 1980. There was no significant difference observed for titer or prevalence by gender, age range and geographic origin.

Conclusion

A simplified, sensitive, standardized, reproducible, and high-throughput assay was developed for the quantitation of NAbs against different Vaccinia strains. The current study provides useful insights for the future development of VTT-based vaccination in Beijing and Anhui provinces of China.

Synthesis and in vitro inhibition properties of oligonucleotide conjugates carrying amphipathic proline-rich peptide derivatives of the sweet arrow peptide (SAP)

In this study, a series of derivatives of the amphipathic proline-rich sweet arrow peptide (SAP) were covalently linked to antisense oligonucleotides designed to inhibit Renilla luciferase gene. Oligonucleotide-peptide conjugates carrying lysine (Lys) and ornithine (Orn) residues were prepared using the stepwise approach by assembling first the peptide sequence followed by the assembly of the DNA molecule. The resulting Lys, Orn-conjugates were transformed to the corresponding arginine and homoarginine oligonucleotide-peptide conjugates by reaction with O-methylisourea. The introduction of the SAP at 3'-termini of a phosphorothioate oligonucleotide did not affect the ability to inhibit gene expression when transfected with lipofectamine. However, these conjugates were not able to enter cells without transfecting agent. Further studies using SAP as a transfection agent showed promising results for the conjugates carrying the Orn-SAP. All conjugates showed high duplex stabilities.

Secreted CXCL12 (SDF-1) forms dimers under physiological conditions

Chemokine CXCL12 (CXC chemokine ligand 12) signalling through CXCR (CXC chemokine receptor) 4 and CXCR7 has essential functions in development and underlies diseases including cancer, atherosclerosis and autoimmunity. Chemokines may form homodimers that regulate receptor binding and signalling, but previous studies with synthetic CXCL12 have produced conflicting evidence for homodimerization. We used bioluminescence imaging with GL (Gaussia luciferase) fusions to investigate dimerization of CXCL12 secreted from mammalian cells. Using column chromatography and GL complementation, we established that CXCL12 was secreted from mammalian cells as both monomers and dimers. Secreted CXCL12 also formed homodimers in the extracellular space. Monomeric CXCL12 preferentially activated CXCR4 signalling through Gαi and Akt, whereas dimeric CXCL12 more effectively promoted recruitment of β-arrestin 2 to CXCR4 and chemotaxis of CXCR4-expressing breast cancer cells. We also showed that CXCR7 preferentially sequestered monomeric CXCL12 from the extracellular space and had minimal effects on dimeric CXCL12 in cell-based assays and an orthotopic tumour xenograft model of human breast cancer. These studies establish that CXCL12 secreted from mammalian cells forms homodimers under physiological conditions. Since monomeric and dimeric CXCL12 have distinct effects on cell signalling and function, our results have important implications for ongoing efforts to target CXCL12 pathways for therapy.

Characterization of human DNA polymerase κ promoter in response to benzo[a]pyrene diol epoxide

DNA polymerase κ (Pol κ), a member of Y-family DNA polymerases, can synthesize DNA with moderate fidelity on undamaged DNAs and replicate accurately in vitro thymine glycol, 8-oxo-G and aromatic adducts such as benzo[a]pyrene diol epoxide (BPDE). However, few studies have been done on the transcriptional regulation of Pol κ. In this study, we predicted and cloned the promoter region of the human POLK gene. Through the analysis of deletion constructs of the POLK promoter, we demonstrated that the region -336/-141 contained repressing elements and the region -141/+226 contained positive regulatory elements for transcription of human Pol κ. Furthermore, quantitative RT-PCR showed that human POLK mRNA expression was dysregulated in FL cells treated by BPDE. The transcriptional activities of the POLK promoter regions -336/+437 and +20/+437 were significantly reduced by BPDE treatment, indicating that transcription factors in this two regions, such as HSF1, may regulate the transcription of human POLK gene in response to BPDE.

Establishment of a transient transfection system and expression of firefly luciferase in Entamoeba invadens

Entamoeba invadens is used as a model system to study trophozoite to cyst differentiation since Entamoeba histolytica, the causative agent of amoebiasis cannot encyst in culture. However, a system for introduction of cloned genes in E. invadens is not available. Here we report an electroporation-based method for transfection of E. invadens tophozoites and demonstrate the expression of firefly luciferase reporter gene driven from the E. invadens ribosomal protein L3 promoter. The efficiency of luciferase expression driven from the promoters of three different E. invadens genes (rpl3, rps10 and h2b) was tested and found to correlate with the in vivo expression levels of the respective gene. This system will permit the analysis of regulatory elements required for gene expression in E. invadens.

Liganded thyroid hormone receptor inhibits phorbol 12-O-tetradecanoate-13-acetate-induced enhancer activity via firefly luciferase cDNA

Thyroid hormone receptor (TR) belongs to the nuclear hormone receptor (NHR) superfamily and regulates the transcription of its target genes in a thyroid hormone (T3)-dependent manner. While the detail of transcriptional activation by T3 (positive regulation) has been clarified, the mechanism of T3-dependent repression (negative regulation) remains to be determined. In addition to naturally occurring negative regulations typically found for the thyrotropin β gene, T3-bound TR (T3/TR) is known to cause artificial negative regulation in reporter assays with cultured cells. For example, T3/TR inhibits the transcriptional activity of the reporter plasmids harboring AP-1 site derived from pUC/pBR322-related plasmid (pUC/AP-1). Artificial negative regulation has also been suggested in the reporter assay with firefly luciferase (FFL) gene. However, identification of the DNA sequence of the FFL gene using deletion analysis was not performed because negative regulation was evaluated by measuring the enzymatic activity of FFL protein. Thus, there remains the possibility that the inhibition by T3 is mediated via a DNA sequence other than FFL cDNA, for instance, pUC/AP-1 site in plasmid backbone. To investigate the function of FFL cDNA as a transcriptional regulatory sequence, we generated pBL-FFL-CAT5 by ligating FFL cDNA in the 5' upstream region to heterologous thymidine kinase promoter in pBL-CAT5, a chloramphenicol acetyl transferase (CAT)-based reporter gene, which lacks pUC/AP-1 site. In kidney-derived CV1 and choriocarcinoma-derived JEG3 cells, pBL-FFL-CAT5, but not pBL-CAT5, was strongly activated by a protein kinase C activator, phorbol 12-O-tetradecanoate-13-acetate (TPA). TPA-induced activity of pBL-FFL-CAT5 was negatively regulated by T3/TR. Mutation of nt. 626/640 in FFL cDNA attenuated the TPA-induced activation and concomitantly abolished the T3-dependent repression. Our data demonstrate that FFL cDNA sequence mediates the TPA-induced transcriptional activity, which is inhibited by T3/TR.

New method for the assessment of molluscum contagiosum virus infectivity

Molluscum contagiosum virus (MCV), a poxvirus pathogenic for humans, replicates well in human skin in vivo, but not in vitro in standard monolayer cell cultures. In order to determine the nature of the replication deficiency in vitro, the MCV infection process in standard culture has to be studied step by step. The method described in this chapter uses luciferase and GFP reporter constructs to measure poxviral mRNA transcription activity in cells in standard culture infected with known quantities of MCV or vaccinia virus. Briefly, MCV isolated from human tissue specimen is quantitated by PCR and used to infect human HEK293 cells, selected for ease of transfection. The cells are subsequently transfected with a reporter plasmid encoding firefly luciferase gene under the control of a synthetic early/late poxviral promoter and a control plasmid encoding a renilla luciferase reporter under the control of a eukaryotic promoter. After 16 h, cells are harvested and tested for expression of luciferase. MCV genome units are quantitated by PCR targeting a genome area conserved between MCV and vaccinia virus. Using a GFP reporter plasmid, this method can be further used to infect a series of epithelial and fibroblast-type cell lines of human and animal origin to microscopically visualize MCV-infected cells, to assess late promoter activation, and, using these parameters, to optimize MCV infectivity and gene expression in more complex eukaryotic cell culture models.

Comparison of red-shifted firefly luciferase Ppy RE9 and conventional Luc2 as bioluminescence imaging reporter genes for in vivo imaging of stem cells

One critical issue for noninvasive imaging of transplanted bioluminescent cells is the large amount of light absorption in tissue when emission wavelengths below 600 nm are used. Luciferase with a red-shifted spectrum can potentially bypass this limitation. We assessed and compared a mutant of firefly luciferase (Ppy RE9, PRE9) against the yellow luciferase luc2 gene for use in cell transplantation studies. C17.2 neural stem cells expressing PRE9-Venus and luc2-Venus were sorted by flow cytometry and assessed for bioluminescence in vitro in culture and in vivo after transplantation into the brain of immunodeficient Rag2-/- mice. We found that the luminescence from PRE9 was stable, with a peak emission at 620 nm, shifted to the red compared to that of luc2. The emission peak for PRE9 was pH-independent, in contrast to luc2, and much less affected by tissue absorbance compared to that of luc2. However, the total emitted light radiance from PRE9 was substantially lower than that of luc2, both in vitro and in vivo. We conclude that PRE9 has favorable properties as compared to luc2 in terms of pH independence, red-shifted spectrum, tissue light penetration, and signal quantification, justifying further optimization of protein expression and enzymatic activity.

A one-time inducible transposon to create knockout mutants in rice

Use of a transposon is an efficient tagging tool for exploring the function of the gene it inserts into or is adjacent to. A few modifications have been applied to the native Ac transposon to allow it to transpose efficiently or spontaneously and stop quickly thereafter. Furthermore, locating the transposon between a constitutive plant promoter and a reporter gene, such as the firefly luciferase gene, allows for nondestructively detecting excision events in vivo. This chapter describes a detailed protocol for one-time inducible transposon tagging of rice cells and their subsequent screening and regeneration into mutant lines.

CTCF and cohesin cooperatively mediate the cell-type specific interchromatin interaction between Bcl11b and Arhgap6 loci

CCCTC-binding factor (CTCF) is a master organizer of genome spatial organization and plays an important role in mediating extensive chromatin interactions. Circular chromosome conformation capture (4C) is a high-throughput approach that allows genome-wide screening for unknown potential interaction partners. Using a conserved CTCF binding site on the Bcl11b locus as bait, an interaction partner at the Arhgap6 locus on a different chromosome was identified by 4C. Additional experiments verified that the interchromatin interaction between the Bcl11b and Arhgap6 loci was cell-type specific, which was cooperatively mediated by CTCF and cohesin. Functional analysis showed that the interchromatin interaction partners were repressing regulatory elements. These results indicate that interaction chromatin loops regulate the expression of the relevant genes.

Genes involved in the metastatic cascade of medullary thyroid tumours

The process of how a benign tumour turns invasive and capable to survive in distant organs remains poorly understood, despite the evidence that metastasis formation is the primary cause of cancer patient mortality. This ignorance is partly due to the lack of appropriate animal models from which to investigate this complex process. The retinoblastoma (Rb) tumour suppressor pathway (pRb/E2F) is mutated in almost all human tumours, and a number of laboratories have now established pRb- or E2F-deficient mouse models. Consistent with the role of mutation in retinoblastoma in cancer biology, Rb heterozygous mice are prone to develop tumours. Among the ensuing tumours, the medullary thyroid carcinomas (MTCs) have a lessened tendency to form secondary cancers and metastases. Intriguingly, if an E2f3 mutation is introduced in this genetic background, more aggressive MTCs develop, which metastasize more frequently. Gene chip microarrays, however, provide an unbiased approach for examining the genome-wide expression levels and enable identification of a large set of metastasis-enriched gene sets. The identified genes may simply represent putative markers of the disease stage. Alternatively, genes may be identified that causally determine a link to the onset of metastasis. We describe the use of gene chip microarrays for identification of putative markers enriched in metastatic mouse MTCs. The chapter details how the most promising candidates are verified using additional methods, such as quantitative real-time PCR. In this case, co-transfection of the E2F-transcription factor using a heterologous reporter gene system is suggestive of E2Fs directly regulating putative metastasis markers.

Collagenase-1 injection improved tumor distribution and gene expression of cationic lipoplex

Elevated interstitial fluid pressure (IFP) in a tumor is a barrier to tumor accumulation of systemic delivery of nanocarriers. In this study, we investigated whether intravenous injection of type I collagenase (collagenase-1) reduced IFP in tumors and increased the accumulation and gene expression of cationic liposome/plasmid DNA complex (lipoplex) in tumors after intravenous injection into mice bearing mouse lung carcinoma LLC tumors. Collagenase-1 reduced the amount of type I collagen in the tumor, and significantly decreased IFP by 65% at 1h after injection. Therefore, collagenase-1 induced 1.5-fold higher accumulation and 2-fold higher gene expression of lipoplex in tumors after intravenous injection. These findings indicated that intravenous injection of collagenase-1 improved the accumulation of lipoplex by decreasing IFP in tumors. These results support the potential use of collagen digestion as a strategy to improve systemic gene delivery into tumors.

Oncogene-targeting T cells reject large tumors while oncogene inactivation selects escape variants in mouse models of cancer

The genetic instability of cancer cells frequently causes drug resistance. We established mouse cancer models, which allowed targeting of an oncogene by drug-mediated inactivation or monospecific CD8(+) effector T (T(E)) cells. Drug treatment of genetically unstable large tumors was effective but selected resistant clones in the long term. In contrast, T(E) cells completely rejected large tumors (≥500 mm(3)), if the target antigen was cancer-driving and expressed in sufficient amounts. Although drug-mediated oncogene inactivation selectively killed the cancer cells and left the tumor vasculature intact, which likely facilitated survival and growth of resistant clones, T(E) cell treatment led to blood vessel destruction and probably "bystander" elimination of escape variants, which did not require antigen cross-presentation by stromal cells.

[Reconstruction and preparation of lentiviral vector system expressing dual-reporter genes]

This study was aimed to construct, package and purify the recombinant lentivirus vector carrying the firefly luciferase gene (FLUC) and red fluorescent protein gene (RFP) and to transfect the recombinant lentivirus into HeLa cells, so as to observe the expression levels of these two genes. The FLUC and RFP genes were amplified by RT-PCR and inserted in the lentiviral expression vector (pLenti-Bi-cistronic) to construct the lentiviral vector pLenti-FLUC-RFP. The viral particles were generated by cotransfection of 293T cells with pLenti-FLUC-RFP and three packaging vectors, and the virus titer was determined by calculating the percentage of RFP positive cells. After transfection of pLenti-FLUC-RFP into HeLa cells, the expression of RFP was observed by fluorescent microscopy, and the activity of FLUC was determined by luciferase reporter gene assay kit. The results showed that the inserting orientation of the RFP and FLUC genes in the lentiviral vector pLenti-FLUC-RFP were verified by restriction analysis. Targeted RFP and FLUC sequences were confirmed by DNA sequencing. The final titer obtained was 1×10(7)TU/ml. The expressions of RFP and FLUC were observed in the transfected HeLa cells. It is concluded that the pLenti-III-FLUC-RFP recombinant lentivirus vector carrying RFP gene and FLUC gene with high viral titer is constructed and packaged successfully, and provides experimental basis for studying dynamic distribution of mesenchymal stem cells in vivo.

Zinc induces chemokine and inflammatory cytokine release from human promonocytes

Our previous studies found that zinc oxide (ZnO) particles induced expression of intercellular adhesion molecule-1 (ICAM-1) protein in vascular endothelial cells via NF-κB and that zinc ions dissolved from ZnO particles might play the major role in the process. This study aimed to determine if zinc ions could cause inflammatory responses in a human promonocytic leukemia cell line HL-CZ. Conditioned media from the zinc-treated HL-CZ cells induced ICAM-1 protein expression in human umbilical vein endothelial cells (HUVEC). Zinc treatment induced chemokine and inflammatory cytokine release from HL-CZ cells. Inhibition of NFκB activity by over-expression of IκBα in HL-CZ cells did not block the conditioned medium-induced ICAM-1 protein expression in HUVEC cells. Zinc treatment induced activation of multiple immune response-related transcription factors in HL-CZ cells. These results clearly show that zinc ions induce chemokine and inflammatory cytokine release from human promonocytes, accompanied with activation of multiple immune response-related transcription factors. Our in vitro evidence in the zinc-induced inflammatory responses of vascular cells provides a critical linkage between zinc exposure and pathogenesis of those inflammatory vascular diseases.

Large-scale protein-protein interaction analysis in Arabidopsis mesophyll protoplasts by split firefly luciferase complementation

Protein-protein interactions (PPIs) constitute the regulatory network that coordinates diverse cellular functions. There are growing needs in plant research for creating protein interaction maps behind complex cellular processes and at a systems biology level. However, only a few approaches have been successfully used for large-scale surveys of PPIs in plants, each having advantages and disadvantages. Here we present split firefly luciferase complementation (SFLC) as a highly sensitive and noninvasive technique for in planta PPI investigation. In this assay, the separate halves of a firefly luciferase can come into close proximity and transiently restore its catalytic activity only when their fusion partners, namely the two proteins of interest, interact with each other. This assay was conferred with quantitativeness and high throughput potential when the Arabidopsis mesophyll protoplast system and a microplate luminometer were employed for protein expression and luciferase measurement, respectively. Using the SFLC assay, we could monitor the dynamics of rapamycin-induced and ascomycin-disrupted interaction between Arabidopsis FRB and human FKBP proteins in a near real-time manner. As a proof of concept for large-scale PPI survey, we further applied the SFLC assay to testing 132 binary PPIs among 8 auxin response factors (ARFs) and 12 Aux/IAA proteins from Arabidopsis. Our results demonstrated that the SFLC assay is ideal for in vivo quantitative PPI analysis in plant cells and is particularly powerful for large-scale binary PPI screens.

Continuous antagonism by Dkk1 counter activates canonical Wnt signaling and promotes cardiomyocyte differentiation of embryonic stem cells

Embryonic stem (ES) cells give rise to mesodermal progenitors that differentiate to hematopoietic and cardiovascular cells. The wnt signaling pathway plays multiple roles in cardiovascular development through a network of intracellular effectors. To monitor global changes in wnt signaling during ES cell differentiation, we generated independent ES cell lines carrying the luciferase gene under promoters that uniquely respond to specific wnt pathway branches. Our results show that successive, mutually exclusive waves of noncanonical and canonical wnt signaling precede mesoderm differentiation. Blocking the initial noncanonical JNK/AP-1 signaling with SP60125 aborts cardiovascular differentiation and promotes hematopoiesis, whereas interference with the subsequent peak of canonical wnt signaling using Dkk1 has the opposite effect. Dkk1 blockade triggers counter mechanisms that lead to delayed and extended activation of canonical wnt signaling and mesoderm differentiation that appear to favor the cardiomyocytic lineage at the expense of hematopoietic cells. The cardiomyocytic yield can be further enhanced by overexpression of Wnt11 leading to approximately 95-fold enrichment in contracting cells. Our results suggest that the initial noncanonical wnt signaling is necessary for subsequent activation of canonical signaling and that the latter operates under a regulatory loop which responds to suppression with hyperactivation of compensatory mechanisms. This model provides new insights on wnt signaling during ES cell differentiation and points to a method to induce cardiomyocytic differentiation without precise timing of wnt signaling manipulation. Taking into account the heterogeneity of pluripotent cells, these findings might present an advantage to enhance the cardiogenic potential of stem cells.

A vesicular stomatitis virus replicon-based bioassay for the rapid and sensitive determination of multi-species type I interferon

Type I interferons (IFN) comprise a family of cytokines that signal through a common cellular receptor to induce a plethora of genes with antiviral and other activities. Recombinant IFNs are used for the treatment of hepatitis C virus infection, multiple sclerosis, and certain malignancies. The capability of type I IFN to suppress virus replication and resultant cytopathic effects is frequently used to measure their bioactivity. However, these assays are time-consuming and require appropriate biosafety containment. In this study, an improved IFN assay is presented which is based on a recombinant vesicular stomatitis virus (VSV) replicon encoding two reporter proteins, firefly luciferase and green fluorescent protein. The vector lacks the essential envelope glycoprotein (G) gene of VSV and is propagated on a G protein-expressing transgenic cell line. Several mammalian and avian cells turned out to be susceptible to infection with the complemented replicon particles. Infected cells readily expressed the reporter proteins at high levels five hours post infection. When human fibroblasts were treated with serial dilutions of human IFN-β prior to infection, reporter expression was accordingly suppressed. This method was more sensitive and faster than a classical IFN bioassay based on VSV cytopathic effects. In addition, the antiviral activity of human IFN-λ (interleukin-29), a type III IFN, was determined on Calu-3 cells. Both IFN-β and IFN-λ were acid-stable, but only IFN-β was resistant to alkaline treatment. The antiviral activities of canine, porcine, and avian type I IFN were analysed with cell lines derived from the corresponding species. This safe bioassay will be useful for the rapid and sensitive quantification of multi-species type I IFN and potentially other antiviral cytokines.

Dietary flavones and flavonones display differential effects on aromatase (CYP19) transcription in the breast cancer cells MCF-7

Aromatase or cytochrome P450 (CYP19) enzyme catalyzes the rate-determining reaction in estrogen synthesis. Inhibiting aromatase is a major strategy in treating breast cancer patients. However, suppression on the transcriptional activity may be equally important in controlling aromatase. Dietary flavones and flavonones have been previously demonstrated to be the most potent aromatase-inhibitory flavonoids. In the present study we examined their effects on the transcription regulation of CYP19 in MCF-7 cells. Real-time PCR results indicated that luteolin suppressed CYP19 mRNA expression while hesperetin increased it. Reporter gene assays were employed to look into the transactivity of CYP19 driven by promoters I.3 and II, and the result was consistent with the observation in mRNA expression. Further investigation using truncation reporter gene and electrophoretic mobility shift assays suggested that luteolin and hesperetin differentially influenced AP-1- and C/EBP-binding on the CYP19 promoter. Western blot analysis indicated that signaling transduction pathways involving JNK and ERK could be the underlying mechanisms for their actions. The present study showed that dietary flavones and flavonones might differentially regulate aromatase transcription in breast cells in addition to the inhibition at the enzyme level.

Role of oxidative stress in hypoxia preconditioning of cells transplanted to the myocardium: a molecular imaging study

AIM

Cell-based therapies are a potential therapeutic alternative for the treatment of coronary artery disease (CAD). However, transplanted cells undergo significant death in the living subject. Hypoxic preconditioning (HPC) is a potential intervention to increase transplanted cell survival. However, the biological mechanisms of this benefit remain unclear. We hypothesize that the beneficial effect of HPC on stem cell survival is in part due to preservation of oxidant status, an effect that will be monitored using state-of-the-art molecular imaging.

METHODS

H9c2 rat cardiomyoblasts expressing the construct CMV-firefly luciferase (h9c2-fluc), with and without HPC, were exposed to hypoxia, and oxidative stress and cell survival were measured. Subsequently, H9c2-fluc cells, with and without HPC, were injected into the myocardium of rats and cell survival was monitored daily with Bioluminescence (BLI) using a CCD camera.

RESULTS

Compared to controls, cells exposed to hypoxia had increased amount of reactive oxygen species (ROS, control: 14.1±0.9 vs. hypoxia: 19.5 ± 2.0 RFU/µg protein, P=0.02) and decreased cell survival (control: 0.29 ± 0.005 vs. hypoxia: 0.24 ± 0.005 OD, P<0.001). HPC treatment decreased the amount of hypoxia-induced ROS (HPC: 11.5 ± 0.7RFU/µg protein, P=0.002 vs. hypoxia and P=0.11 vs. control), associated with improved survival (HPC: 0.27 ± 0.004OD/µg protein, P=0.002 vs. hypoxia and P=0.005 vs. control). Most importantly, compared to un-conditioned cells, HPC-cells had increased cell survival after transplantation to the myocardium (C: 34.7 ± 6.7% vs. HPC: 83.4 ± 17.5% at day 5 compared to day 1, P=0.01).

CONCLUSION

The beneficial effect of HPC is in part due to preservation of oxidant status. Molecular imaging can assess changes in cell survival in the living subject and has the potential to be applied clinically.

Transcriptome analysis of aldosterone-regulated genes in human vascular endothelial cell lines stably expressing mineralocorticoid receptor

A series of studies have demonstrated that endothelial cell is one of the target tissues of aldosterone. Here, we have conducted a transcriptome analysis of aldosterone-inducible genes in human endothelial cell lines stably expressing human mineralocorticoid receptor (MR) by retroviral system (MR-EAhy). We found that aldosterone in physiologic concentrations robustly induced MR-dependent transcriptional response in MR-EAhy. By DNA microarray analysis, we validated 12 aldosterone-up-regulated genes among which at least seven were concomitantly associated with increased protein expression. We also found five aldosterone-down-regulated genes. Among 11 aldosterone-up-regulated genes tested, mRNA expressions of three (ESM1, SNF1LK, ANGPTL4) were significantly up-regulated in aortic tissue from aldosterone-induced hypertensive rats compared to those from control rats, suggesting their potential pathophysiologic significance in vivo. In conclusion, using MR stably expressed human endothelial cell lines, we identified a variety of aldosterone-inducible genes, suggesting their possible roles in the development and/or the protection for aldosterone-induced vascular injury.

Sequential bioluminescence resonance energy transfer-fluorescence resonance energy transfer-based ratiometric protease assays with fusion proteins of firefly luciferase and red fluorescent protein

We report here the preparation of ratiometric luminescent probes that contain two well-separated emission peaks produced by a sequential bioluminescence resonance energy transfer (BRET)-fluorescence resonance energy transfer (FRET) process. The probes are single soluble fusion proteins consisting of a thermostable firefly luciferase variant that catalyze yellow-green (560nm maximum) bioluminescence and a red fluorescent protein covalently labeled with a near-infrared fluorescent dye. The two proteins are connected by a decapeptide containing a protease recognition site specific for factor Xa, thrombin, or caspase 3. The rates of protease cleavage of the fusion protein substrates were monitored by recording emission spectra and plotting the change in peak ratios over time. Detection limits of 0.41nM for caspase 3, 1.0nM for thrombin, and 58nM for factor Xa were realized with a scanning fluorometer. Our results demonstrate for the first time that an efficient sequential BRET-FRET energy transfer process based on firefly luciferase bioluminescence can be employed to assay physiologically important protease activities.

Pulse duration determines levels of Hsp70 induction in tissues following laser irradiation

Induction of heat shock protein (Hsp) expression correlates with cytoprotection, reduced tissue damage, and accelerated healing in animal models. Since Hsps are transcriptionally activated in response to stress, they can act as stress indicators in burn injury or surgical procedures that produce heat and thermal change. A fast in vivo readout for induction of Hsp transcription in tissues would allow for the study of these proteins as therapeutic effect mediators and reporters of thermal stress∕damage. We used a transgenic reporter mouse in which a luciferase expression is controlled by the regulatory region of the inducible 70 kilodalton (kDa) Hsp as a rapid readout of cellular responses to laser-mediated thermal stress∕injury in mouse skin. We assessed the pulse duration dependence of the Hsp70 expression after irradiation with a CO(2) laser at 10.6 μm in wavelength over a range of 1000 to 1 ms. Hsp70 induction varied with changes in laser pulse durations and radiant exposures, which defined the ranges at which thermal activation of Hsp70 can be used to protect cells from subsequent stress, and reveals the window of thermal stress that tissues can endure.

Multiple roles of WIN3 in regulating disease resistance, cell death, and flowering time in Arabidopsis

The salicylic acid (SA) regulatory gene HOPW1-1-INTERACTING3 (WIN3) was previously shown to confer resistance to the biotrophic pathogen Pseudomonas syringae. Here, we report that WIN3 controls broad-spectrum disease resistance to the necrotrophic pathogen Botrytis cinerea and contributes to basal defense induced by flg22, a 22-amino acid peptide derived from the conserved region of bacterial flagellin proteins. Genetic analysis indicates that WIN3 acts additively with several known SA regulators, including PHYTOALEXIN DEFICIENT4, NONEXPRESSOR OF PR GENES1 (NPR1), and SA INDUCTION-DEFICIENT2, in regulating SA accumulation, cell death, and/or disease resistance in the Arabidopsis (Arabidopsis thaliana) mutant acd6-1. Interestingly, expression of WIN3 is also dependent on these SA regulators and can be activated by cell death, suggesting that WIN3-mediated signaling is interconnected with those derived from other SA regulators and cell death. Surprisingly, we found that WIN3 and NPR1 synergistically affect flowering time via influencing the expression of flowering regulatory genes FLOWERING LOCUS C and FLOWERING LOCUS T. Taken together, our data reveal that WIN3 represents a novel node in the SA signaling networks to regulate plant defense and flowering time. They also highlight that plant innate immunity and development are closely connected processes, precise regulation of which should be important for the fitness of plants.

Stimulatory effect of pituitary adenylate-cyclase activating polypeptide (PACAP) and its PACAP type I receptor (PAC1R) on prolactin synthesis in rat pituitary somatolactotroph GH3 cells

In this present study, we investigated the role of pituitary adenylate cyclase-activating polypeptide (PACAP) and its receptor, PACAP type I receptor (PAC1R) on prolactin synthesis in pituitary somatolactotroph GH3 cells. PACAP increased prolactin promoter activity up to 1.3 ± 0.1-fold. This increase, while significant, was less than the increase resulting from thyrotropin-releasing hormone (TRH) stimulation. By transfection of a PAC1R expression vector to the cells, the response to PACAP on prolactin promoter activity was dramatically potentiated to a degree proportional to the amount of PAC1R transfected. In the PAC1R expressing GH3 cells, TRH and PACAP alone increased prolactin promoter up to 3.3 ± 0.3-fold and 4.9 ± 0.2-fold, respectively, and combined treatment with TRH and PACAP further increased prolactin promoters up to 6.8 ± 0.6-fold. PACAP binds both Gs- and Gq-coupled receptors and stimulates adenylate cyclase/cAMP and protein kinase C/extracellular signal-regulated kinase (ERK) signaling pathways. PACAP increased ERK phosphorylation in PAC1R expressing cells to the same degree as TRH. Combined treatment with TRH and PACAP had a synergistic effect on ERK activation. GH3 cells produce both prolactin and growth hormone. Stimulation of GH3 cells with TRH significantly increased the mRNA level of prolactin and attenuated growth hormone mRNA expression. PACAP increased both prolactin and growth hormone mRNA levels, particularly in PAC1R expressing cells. In addition, increasing amount of PAC1R in GH3 cells potentiated the action of TRH on prolactin promoter activity, as well as on ERK phosphorylation. PAC1R was induced by PACAP itself, but not by TRH. Our current study demonstrates that PACAP and its PAC1R, functions as a stimulator of prolactin alone or with TRH in prolactin producing cells.