Name: transfecting raw264.7 cells with a luciferase reporter gene
Uploaded: 2015-06-18T14:00:00
Description: Watch this Scientific Journal Video about Transfecting RAW264.7 Cells with a Luciferase Reporter Gene at JoVE.com

This study was funded by Canadian Institutes for Health Research (CIHR) grant. STC holds a doctoral research award from the CIHR and the Michael Smith Foundation. EYS holds a CIHR scholarship. The CIHR Transplantation Training Program also provided graduate scholarships to STC, EYS and SS.

1. Plasmid DNA Purification
<ol>
	<li>Extract plasmid DNA using a maxiprep kit according to the manufacturer&#8217;s protocol. Resuspend plasmid DNA in 500 &#181;l of TE buffer.</li>
	<li>Perform a phenol:chloroform:isoamyl alcohol extraction and isopropanol precipitation to remove residual bacterial contaminants. The presence of LPS interferes with transfection9.
	<ol>
		<li>Add 500 &#181;l of phenol:chloroform:isoamyl alcohol (25:24:1, pH 8) to the plasmid DNA and shake vigorously for 15 sec. Phenol causes...

<ol>
	<li>Maurisse, R., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Comparative+transfection+of+DNA+into+primary+and+transformed+mammalian+cells+from+different+lineages.">Comparative transfection of DNA into primary and transformed mammalian cells from different lineages.</a> BMC Biotechnol. 10 (1), 9-18 (2010).</li><li>Thompson, C. D., Frazier-Jessen, M. R., Rawat, R., Nordan, R. P., Brown, R. T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Evaluation+of+methods+for+transient+transfection+of+a+murine+macrophage+cell+line+RAW+264.7.">Evaluation of methods for transient transfection of a murine macrophage cell line RAW 264.7.</a> Biotechniques. 27 (4), 824-835 (1999).</li><li>Kim, T., Eberwine, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mammalian+cell+transfection:+the+present+and+the+future.">Mammalian cell transfection: the present and the future.</a> Analytical and Bioanalytical Chemistry. 397 (8), 3173-3178 (2010).</li><li>Stacey, K. J., Sweet, M. J., Hume, D. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Macrophages+ingest+and+are+activated+by+bacterial+DNA.">Macrophages ingest and are activated by bacterial DNA.</a> Journal of immunology. 157 (5), 2116-2122 (1996).</li><li>Jiang, W., Reich, I. C., Pisetsky, D. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mechanisms+of+activation+of+the+RAW264.7+macrophage+cell+line+by+transfected+mammalian+DNA.">Mechanisms of activation of the RAW264.7 macrophage cell line by transfected mammalian DNA.</a> Cell Immunol. 229 (1), 31-42 (2004).</li><li>Jiang, W., Pisetsky, D. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+induction+of+HMGB1+release+from+RAW+264.7+cells+by+transfected+DNA.">The induction of HMGB1 release from RAW 264.7 cells by transfected DNA.</a> Mol Immunol. 45 (7), 2038-2046 (2008).</li><li>Hargreaves, D. C., Horng, T., Medzhitov, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Control+of+inducible+gene+expression+by+signal-dependent+transcriptional+elongation.">Control of inducible gene expression by signal-dependent transcriptional elongation.</a> Cell. 138 (1), 129-147 (2009).</li><li>Cheung, S. T., So, E. Y., Chang, D., Ming-Lum, A., Mui, A. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Interleukin-10+inhibits+lipopolysaccharide+induced+miR-155+precursor+stability+and+maturation.">Interleukin-10 inhibits lipopolysaccharide induced miR-155 precursor stability and maturation.</a> PLoS One. 8 (8), e71336 (2013).</li><li>Weber, M., Moller, K., Welzeck, M., Schorr, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Short+technical+reports.+Effects+of+lipopolysaccharide+on+transfection+efficiency+in+eukaryotic+cells.">Short technical reports. Effects of lipopolysaccharide on transfection efficiency in eukaryotic cells.</a> Biotechniques. 19 (6), 930-940 (1995).</li><li>Berghaus, L. J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Innate+immune+responses+of+primary+murine+macrophage-lineage+cells+and+RAW+264.7+cells+to+ligands+of+Toll-like+receptors.">Innate immune responses of primary murine macrophage-lineage cells and RAW 264.7 cells to ligands of Toll-like receptors.</a> Comp Immunol Microbiol Infect Dis. 33 (5), 443-456 (2000).</li><li>Fiszer-Kierzkowska, A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Liposome-based+DNA+carriers+may+induce+cellular+stress+response+and+change+gene+expression+pattern+in+transfected+cells.">Liposome-based DNA carriers may induce cellular stress response and change gene expression pattern in transfected cells.</a> BMC Mol Biol. 12 (1), 27-36 (2011).</li><li>Jacobsen, L., Calvin, S., Lobenhofer, E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Transcriptional+effects+of+transfection:+the+potential+for+misinterpretation+of+gene+expression+data+generated+from+transiently+transfected+cells.">Transcriptional effects of transfection: the potential for misinterpretation of gene expression data generated from transiently transfected cells.</a> Biotechniques. 47 (7), 617-626 (2009).</li></ol>

The protocol described here does not solely focus on transfection efficiency, but aims to strike a balance between efficiency and preservation of the physiological states of the cells. Specifically, our procedure succeeds in minimizing the toxicity of transfection reagent and maximizing luciferase signal.
One critical step in the protocol is the health of the cells. Overgrown cultures are not suitable for transfection as their physiology changes, and continuous culturing of RAW264.7 cells for ...

Transfection of nucleic acids in cells has a diverse application in scientific research. Examples include (1) reporter genes to study the role of different gene elements in gene expression, (2) protein expression plasmids to overexpress the protein of interest, and (3) small interfering RNA to downregulate gene expression. By manipulating the expression level of particular genes and measuring the differential effect of such manipulations, researchers can deduce the gene functions in the chosen biological systems. Not all transfection methods provide the same transfection efficiencies, and even the same transfection method does not transfect all cell types equally1. Hence, different transfection methods have been developed such as calcium phosphate method, DEAE dextran, cationic lipid transfection, cationic non-lipid polymer transfection, electroporation, and nucleofection2,3.
Transfection into macrophages is especially difficult due to the fact that macrophages are professional phagocytes that are very sensitive to foreign materials including bacteria derived (methylated) DNA4. Introduction of foreign DNA activates the Toll-like receptor 9 (TLR9) pathway leading to the production of cytokines and nitric oxide5,6. These activated macrophages may then be less responsive to treatment that the researchers intend to examine.
Our lab routinely transfects the RAW264.7 macrophage cell line with luciferase reporter genes, and we have developed a protocol that is robust enough to have luciferase signal significantly higher than background, but also gentle enough for macrophages to remain at their resting state. The behaviours of the transfected cells were evaluated by a firefly-luciferase reporter gene harbouring the promoter region of I&#954;B&#950; (pGL3- I&#954;B&#950;). I&#954;B&#950; expression is upregulated by the bacterial cell wall component lipopolyssacharide (LPS)7,8, and downregulated by the anti-inflammatory cytokine, Interleukin-10 (IL-10)8. To account for transfection variation among wells, we co-transfect a control plasmid containing the Renilla luciferase gene (e.g., phRL-TK) for normalization purposes. The protocol described is optimized after testing various parameters including timing of transfection, type of transfection reagents, amounts of transfection reagents and of plasmid DNA, as well as ratio of transfection reagent to plasmid DNA. The two transfection reagents included in this protocol are (1) a lipid-based transfection reagent and (2) a protein/polyamine-based transfection reagent.

<table border="0" cellpadding="0" cellspacing="0">
	<tbody>
		<tr>
			<td>PureLink HiPure Plasmid Maxiprep Kit</td>
			<td>Life Technologies</td>
			<td>K210007</td>
			<td>Any maxiprep kit will work</td>
		</tr>
		<tr>
			<td>Phenol:chloroform:isoamyl alcohol</td>
			<td>Life Technologies</td>
			<td>15593-049</td>
			<td>Molecular Biology Grade. Phenol is toxic so work in the fume hood, if possible. Use the lower clear organic layer if two layers of liquid form in the container.</td>
		</tr>
		<tr>
			<td>DMEM</td>
			<td>Thermo Scientific</td>
			<td>SH30243.01</td>
			<td>Warm in 37&#176;C water bath before use.&#160;</td>
		</tr>
		<tr>
			<td>Fetal Bovine Serum</td>
			<td>Thermo Scientific</td>
			<td>SH30396.03</td>
			<td>Inactivated at 56&#176;C water bath for 45 minutes before use.</td>
		</tr>
		<tr>
			<td>Opti-MEM</td>
			<td>Life Technologies</td>
			<td>31985-070</td>
			<td>Warm to at least room temperature before use.</td>
		</tr>
		<tr>
			<td>XtremeGene HP DBA transfection reagent</td>
			<td>Roche</td>
			<td>6366236001</td>
			<td>Warm to room temperature before use.&#160;</td>
		</tr>
		<tr>
			<td>GeneJuice</td>
			<td>EMD Millipore</td>
			<td>70967</td>
			<td>Warm to room temperature before use.&#160;</td>
		</tr>
		<tr>
			<td>5X Passive Lysis Buffer</td>
			<td>Promega</td>
			<td>E1941</td>
			<td>30 ml is included in the Dual Luciferase Reporter Assay System</td>
		</tr>
		<tr>
			<td>Dual Luciferase Reporter Assay System</td>
			<td>Promega</td>
			<td>E1910</td>
			<td></td>
		</tr>
	</tbody>
</table>

transfecting raw264.7 cells with a luciferase reporter gene

Transfection of desired genetic materials into cells is an inevitable procedure in biomedical research studies. While numerous methods have been described, certain types of cells are resistant to many of these methods and yield low transfection efficiency1, potentially hindering research in those cell types. In this protocol, we present an optimized transfection procedure to introduce luciferase reporter genes as a plasmid DNA into the RAW264.7 macrophage cell line. Two different types of transfection reagents (lipid-based and polyamine-based) are described, and important notes are given throughout the protocol to ensure that the RAW264.7 cells are minimally altered by the transfection procedure and any experimental data obtained are the direct results of the experimental treatment. While transfection efficiency may not be higher compared to other transfection methods, the described procedure is robust enough for detecting luciferase signal in RAW264.7 without changing the physiological response of the cells to stimuli.

Figure 1 compares the transfection efficiency of the two transfection reagents in RAW264.7. The lipid-based reagent typically gave about 25% transfection rate while the protein/polyamine-based transfection resulted in about 5% efficiency (Figure 1A). The difference in transfection efficiency was also observed in luciferase signals in RAW264.7 cells transfected with the pGL3-I&#954;B&#950; promoter reporter (Figure 1B). Addition of LPS to these transfected cells increased...

Watch this Scientific Journal Video about Transfecting RAW264.7 Cells with a Luciferase Reporter Gene at JoVE.com

Transfecting RAW264.7 Cells with a Luciferase Reporter Gene

Transfection into the macrophage cell line, RAW264.7, is difficult due to the cell&#8217;s natural response against foreign materials. We described here a gentle yet robust procedure for transfecting luciferase reporter genes into RAW264.7 cells.

Transfection of desired genetic materials into cells is an inevitable procedure in biomedical research studies. While numerous methods have been ...

transfecting-raw2647-cells-with-a-luciferase-reporter-gene

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Biology

Transfecting Human Neural Stem Cells with the Amaxa Nucleofector

Transfection of primary mammalian neural cells, such as human neural stem/precursor cells (hNSPCs), with commonly used cationic lipid transfection reagents has often resulted in poor cell viability and low transfection efficiency.  Other mechanical methods of introducing a gene of interest, such as a &#8220;gene gun&#8221; or microinjection, are also limited by poor cell viability and low numbers of transfected cells.  The strategy of using viral constructs to introduce an exogenous gene into primary cells has been constrained by both the amount of time and labor required to create viral vectors and potential safety concerns.  We describe here a step-by-step protocol for transfecting hNSPCs using Amaxa's Nucleofector device and technology with electrical current parameters and buffer solutions specifically optimized for transfecting neural stem cells.  Using this protocol, we have achieved initial transfection efficiencies of ~35% and ~70% after stable transfection.  The protocol entails combining a high number of hNSPCs with the DNA to be transfected in the appropriate buffer followed by electroporation with the Nucleofector device.

Introducing a gene of interest into a cell is a powerful method for elucidating its function in vivo. This protocol describes an efficient method of transfecting a culture of human neural stem/precursor cells (hNSPCs) using the Nucleofector electroporation apparatus made by Amaxa.

Transfection of primary mammalian neural cells, such as human neural stem/precursor cells (hNSPCs), with commonly used cationic lipid transfection ...

In vitro and in vivo Bioluminescence Reporter Gene Imaging of Human Embryonic Stem Cells

The discovery of human embryonic stem cells (hESCs) has dramatically increased the tools available to medical scientists interested in regenerative medicine. However, direct injection of hESCs, and cells differentiated from hESCs, into living organisms has thus far been hampered by significant cell death, teratoma formation, and host immune rejection. Understanding the in vivo hESC behavior after transplantation requires novel imaging techniques to longitudinally monitor hESC localization, proliferation, and viability. Molecular imaging has given investigators a high-throughput, inexpensive, and sensitive means for tracking in vivo cell proliferation over days, weeks, and even months. This advancement has significantly increased the understanding of the spatio-temporal kinetics of hESC engraftment, proliferation, and teratoma-formation in living subjects.

A major advance in molecular imaging has been the extension of noninvasive reporter gene assays from molecular and cellular biology into in vivo multi-modality imaging platforms. These reporter genes, under control of engineered promoters and enhancers that take advantage of the host cell s transcriptional machinery, are introduced into cells using a variety of vector and non-vector methods. Once in the cell, reporter genes can be transcribed either constitutively or only under specific biological or cellular conditions, depending on the type of promoter used. Transcription and translation of reporter genes into bioactive proteins is then detected with sensitive, noninvasive instrumentation (e.g., CCD cameras) using signal-generating probes such as D-luciferin.

To avoid the need for excitatory light to track stem cells in vivo as is required for fluorescence imaging, bioluminescence reporter gene imaging systems require only an exogenously administered probe to induce light emission. Firefly luciferase, derived from the firefly Photinus pyralis, encodes an enzyme that catalyzes D-luciferin to the optically active metabolite, oxyluciferin. Optical activity can then be monitored with an external CCD camera. Stably transduced cells that carry the reporter construct within their chromosomal DNA will pass the reporter construct DNA to daughter cells, allowing for longitudinal monitoring of hESC survival and proliferation in vivo. Furthermore, because expression of the reporter gene product is required for signal generation, only viable parent and daughter cells will create bioluminescence signal; apoptotic or dead cells will not. 

In this video, the specific materials and methods needed for tracking stem cell proliferation and teratoma formation with bioluminescence imaging will be described.

With the growing interest in stem cell therapies, molecular imaging techniques are ideal for monitoring stem cell behavior after transplantation. Luciferase reporter genes have enabled non-invasive, repetitive assessment of cell survival, location, and proliferation in vivo. This video will demonstrate how to track hESC proliferation in a living mouse.

The discovery of human embryonic stem cells (hESCs) has dramatically increased the tools available to medical scientists interested in regenerative ...

Studying Membrane Biogenesis with a Luciferase-Based Reporter Gene Assay

To study the coordination of different lipid synthesis pathways during membrane biogenesis it is useful to work with an experimental system where membrane biogenesis occurs rapidly and in an inducible manner. We have found that phagocytosis of latex beads is practical for these purposes as cells rapidly synthesize membrane lipids to replenish membrane pools lost as  wrapping material  during particle engulfment. Here, we describe procedures for studying changes in phagocytosis-induced gene expression with a luciferase-based reporter gene approach using the Dual-Glo  Luciferase Assay System from Promega.

Here, we describe procedures for studying changes in phagocytosis-induced gene expression with a luciferase-based reporter gene approach using the Dual-GloTM Luciferase Assay System from Promega.

To study the coordination of different lipid synthesis pathways during membrane biogenesis it is useful to work with an experimental system where membrane ...

Using the Gene Pulser MXcell Electroporation System to Transfect Primary Cells with High Efficiency

It is becoming increasingly apparent that electroporation is the most effective way to introduce plasmid DNA or siRNA into primary cells. The Gene Pulser MXcell electroporation system and Gene Pulser electroporation buffer (Bio-Rad) were specifically developed to easily transfect nucleic acids into mammalian cells and difficult-to-transfect cells, such as primary and stem cells. We will demonstrate how to perform a simple experiment to quickly identify the best electroporation conditions. We will demonstrate how to run several samples through a range of electroporation conditions so that an experiment can be conducted at the same time as optimization is performed. We will also show how optimal conditions identified using 96-well electroporation plates can be used with standard electroporation cuvettes, facilitating the switch from electroporation plates to electroporation cuvettes while maintaining the same electroporation efficiency. In the video, we will also discuss some of the key factors that can lead to the success or failure of electroporation experiments.

This procedure shows how to use the Gene Pulser MXcell electroporation system to rapidly and easily identify the best electroporation conditions for mouse embryonic fibroblasts (MEFs) or other primary cells. Considerations for troubleshooting are also discussed in the associated video.

It is becoming increasingly apparent that electroporation is the most effective way to introduce plasmid DNA or siRNA into primary cells. The Gene Pulser ...

Using an Automated Cell Counter to Simplify Gene Expression Studies: siRNA Knockdown of IL-4 Dependent Gene Expression in Namalwa Cells

The use of siRNA mediated gene knockdown is continuing to be an important tool in studies of gene expression.  siRNA studies are being conducted not only to study the effects of downregulating single genes, but also to interrogate signaling pathways and other complex interaction networks.  These pathway analyses require both the use of relevant cellular models and methods that cause less perturbation to the cellular physiology.  Electroporation is increasingly being used as an effective way to introduce siRNA and other nucleic acids into difficult to transfect cell lines and primary cells without altering the signaling pathway under investigation. There are multiple critical steps to a successful siRNA experiment, and there are ways to simplify the work while improving the data quality at several experimental stages.  To help you get started with your siRNA mediated gene knockdown project, we will demonstrate how to perform a pathway study complete from collecting and counting the cells prior to electroporation through post transfection real-time PCR gene expression analysis.  The following study investigates the role of the transcriptional activator STAT6 in IL-4 dependent gene expression of CCL17 in a Burkitt lymphoma cell line (Namalwa).  The techniques demonstrated are useful for a wide range of siRNA-based experiments on both adherent and suspension cells.  We will also show how to streamline cell counting with the TC10 automated cell counter, how to electroporate multiple samples simultaneously using the MXcell electroporation system, and how to simultaneously assess RNA quality and quantity with the Experion automated electrophoresis system.

This procedure describes a quick and easy workflow to introduce siRNA into difficult to transfect cell lines and follow gene expression by real-time PCR. Use of an automated cell counter, multi-well electroporation plate, and automated electrophoresis station provide quick and reliable results without the need for expensive robotic handling.

The use of siRNA mediated gene knockdown is continuing to be an important tool in studies of gene expression.  siRNA studies are being conducted not only ...

Floral-dip Transformation of Arabidopsis thaliana to Examine pTSO2::&beta;-glucuronidase Reporter Gene Expression

The ability to introduce foreign genes into an organism is the foundation for modern biology and biotechnology. In the model flowering plant Arabidopsis thaliana, the floral-dip transformation method1-2 has replaced all previous methods because of its simplicity, efficiency, and low cost. Specifically, shoots of young flowering Arabidopsis plants are dipped in a solution of Agrobacterium tumefaciens carrying specific plasmid constructs. After dipping, the plants are returned to normal growth and yield seeds, a small percentage of which are transformed with the foreign gene and can be selected for on medium containing antibiotics. This floral-dip method significantly facilitated Arabidopsis research and contributed greatly to our understanding of plant gene function. In this study, we use the floral-dip method to transform a reporter gene, &beta;-glucuronidase (GUS), under the control of TSO2 promoter. TSO2, coding for the Ribonucleotide Reductase (RNR) small subunit3, is a cell cycle regulated gene essential for dNDP biosynthesis in the S-phase of the cell cycle. Examination of GUS expression in transgenic Arabidopsis seedlings shows that TSO2 is expressed in actively dividing tissues. The reported experimental method and materials can be easily adapted not only for research but also for education at high school and college levels.

Floral-dip Transformation of Arabidopsis thaliana to Examine pTSO2::&amp;#946;-glucuronidase Reporter Gene Expression

This article illustrates the floral-dip method of Agrobacterium tumefaciens -mediated transformation of Arabidopsis thaliana. By introducing a cell-cycle regulated promoter-reporter, pTSO2::&beta;-glucuronidase (GUS), into Arabidopsis, we illustrates how one detects GUS reporter expression in transgenic seedlings.

The ability to introduce foreign genes into an organism is the foundation for modern biology and biotechnology. In the model flowering plant Arabidopsis ...

Transfecting and Nucleofecting Human Induced Pluripotent Stem Cells

Genetic modification is continuing to be an essential tool in studying stem cell biology and in setting forth potential clinical applications of human embryonic stem cells (HESCs)1. While improvements in several gene delivery methods have been described2-9, transfection remains a capricious process for HESCs, and has not yet been reported in human induced pluripotent stem cells (iPSCs). In this video, we demonstrate how our lab routinely transfects and nucleofects human iPSCs using plasmid with an enhanced green fluorescence protein (eGFP) reporter. Human iPSCs are adapted and maintained as feeder-free cultures to eliminate the possibility of feeder cell transfection and to allow efficient selection of stable transgenic iPSC clones following transfection. For nucleofection, human iPSCs are pre-treated with ROCK inhibitor11, trypsinized into small clumps of cells, nucleofected and replated on feeders in feeder cell-conditioned medium to enhance cell recovery. Transgene-expressing human iPSCs can be obtained after 6 hours. Antibiotic selection is applied after 24 hours and stable transgenic lines appear within 1 week. Our protocol is robust and reproducible for human iPSC lines without altering pluripotency of these cells.

Despite recent advancements in genetic modification, transfection of human embryonic stem cells (HESCs) remains a capricious process. To our knowledge, systematic and efficient methods to transfect human induced pluripotent stem cells (iPSCs) have not been reported. Here, we describe robust protocols to efficiently transfect and nucleofect human iPSCs.

Genetic modification is continuing to be an essential tool in studying stem cell biology and in setting forth potential clinical applications of human ...

Identifying Targets of Human microRNAs with the LightSwitch Luciferase Assay System using 3'UTR-reporter Constructs and a microRNA Mimic in Adherent Cells

MicroRNAs (miRNAs) are important regulators of gene expression and play a role in many biological processes. More than 700 human miRNAs have been identified so far with each having up to hundreds of unique target mRNAs. Computational tools, expression and proteomics assays, and chromatin-immunoprecipitation-based techniques provide important clues for identifying mRNAs that are direct targets of a particular miRNA. In addition, 3'UTR-reporter assays have become an important component of thorough miRNA target studies because they provide functional evidence for and quantitate the effects of specific miRNA-3'UTR interactions in a cell-based system. To enable more researchers to leverage 3'UTR-reporter assays and to support the scale-up of such assays to high-throughput levels, we have created a genome-wide collection of human 3'UTR luciferase reporters in the highly-optimized LightSwitch Luciferase Assay System. The system also includes synthetic miRNA target reporter constructs for use as positive controls, various endogenous 3'UTR reporter constructs, and a series of standardized experimental protocols.
Here we describe a method for co-transfection of individual 3'UTR-reporter constructs along with a miRNA mimic that is efficient, reproducible, and amenable to high-throughput analysis.

Identifying Targets of Human microRNAs with the LightSwitch Luciferase Assay System using 3&#039;UTR-reporter Constructs and a microRNA Mimic in Adherent Cells

MicroRNAs (miRNAs) are important regulators of gene expression and have been shown to play a role in numerous biological processes. To better understand miRNA-UTR interactions, we have created a genome-wide collection of 3 UTR luciferase reporters paired with a novel luciferase gene and assay reagent, the LightSwitch system.

MicroRNAs (miRNAs) are important regulators of gene expression and play a role in many biological processes.  More than 700 human miRNAs have been ...

Monitoring Cell-autonomous Circadian Clock Rhythms of Gene Expression Using Luciferase Bioluminescence Reporters

In mammals, many aspects of behavior and physiology such as sleep-wake cycles and liver metabolism are regulated by endogenous circadian clocks (reviewed1,2). The circadian time-keeping system is a hierarchical multi-oscillator network, with the central clock located in the suprachiasmatic nucleus (SCN) synchronizing and coordinating extra-SCN and peripheral clocks elsewhere1,2. Individual cells are the functional units for generation and maintenance of circadian rhythms3,4, and these oscillators of different tissue types in the organism share a remarkably similar biochemical negative feedback mechanism. However, due to interactions at the neuronal network level in the SCN and through rhythmic, systemic cues at the organismal level, circadian rhythms at the organismal level are not necessarily cell-autonomous5-7. Compared to traditional studies of locomotor activity in vivo and SCN explants ex vivo, cell-based in vitro assays allow for discovery of cell-autonomous circadian defects5,8. Strategically, cell-based models are more experimentally tractable for phenotypic characterization and rapid discovery of basic clock mechanisms5,8-13.
Because circadian rhythms are dynamic, longitudinal measurements with high temporal resolution are needed to assess clock function. In recent years, real-time bioluminescence recording using firefly luciferase as a reporter has become a common technique for studying circadian rhythms in mammals14,15, as it allows for examination of the persistence and dynamics of molecular rhythms. To monitor cell-autonomous circadian rhythms of gene expression, luciferase reporters can be introduced into cells via transient transfection13,16,17 or stable transduction5,10,18,19. Here we describe a stable transduction protocol using lentivirus-mediated gene delivery. The lentiviral vector system is superior to traditional methods such as transient transfection and germline transmission because of its efficiency and versatility: it permits efficient delivery and stable integration into the host genome of both dividing and non-dividing cells20. Once a reporter cell line is established, the dynamics of clock function can be examined through bioluminescence recording. We first describe the generation of P(Per2)-dLuc reporter lines, and then present data from this and other circadian reporters. In these assays, 3T3 mouse fibroblasts and U2OS human osteosarcoma cells are used as cellular models. We also discuss various ways of using these clock models in circadian studies. Methods described here can be applied to a great variety of cell types to study the cellular and molecular basis of circadian clocks, and may prove useful in tackling problems in other biological systems.

Circadian clocks function within individual cells, i.e., they are cell-autonomous. Here, we describe methods for generating cell-autonomous clock models using non-invasive, luciferase-based real-time bioluminescence technology. Reporter cells provide tractable, functional model systems for studying circadian biology.

In mammals, many aspects of behavior and physiology such as sleep-wake cycles and liver metabolism are regulated by endogenous circadian clocks ...

A Chemical Screening Procedure for Glucocorticoid Signaling with a Zebrafish Larva Luciferase Reporter System

Glucocorticoid stress hormones and their artificial derivatives are widely used drugs to treat inflammation, but long-term treatment with glucocorticoids can lead to severe side effects. Test systems are needed to search for novel compounds influencing glucocorticoid signaling in vivo or to determine unwanted effects of compounds on the glucocorticoid signaling pathway. We have established a transgenic zebrafish assay which allows the measurement of glucocorticoid signaling activity in vivo and in real-time, the GRIZLY assay (Glucocorticoid Responsive In vivo Zebrafish Luciferase activitY). The luciferase-based assay detects effects on glucocorticoid signaling with high sensitivity and specificity, including effects by compounds that require metabolization or affect endogenous glucocorticoid production. We present here a detailed protocol for conducting chemical screens with this assay. We describe data acquisition, normalization, and analysis, placing a focus on quality control and data visualization. The assay provides a simple, time-resolved, and quantitative readout. It can be operated as a stand-alone platform, but is also easily integrated into high-throughput screening workflows. It furthermore allows for many applications beyond chemical screening, such as environmental monitoring of endocrine disruptors or stress research.

We describe the procedure and data analysis of a chemical screening system for glucocorticoid stress hormone signaling using zebrafish larvae: the Glucocorticoid Responsive In vivo Zebrafish Luciferase activitY (GRIZLY) assay. The assay sensitively and specifically detects effects on glucocorticoid signaling by compounds that require metabolization or affect endogenous glucocorticoid production.

Glucocorticoid stress hormones and their artificial derivatives are widely used drugs to treat inflammation, but long-term treatment with glucocorticoids ...