Team:DTU-Denmark-2/results/Proofofconcept/mammalian

From 2011.igem.org

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<a href="https://2011.igem.org/Team:DTU-Denmark-2/results/Proofofconcept/mammalian#Mammalian cells" class="h1"> Mammalian cells</a><br><br>
 
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<a href="https://2011.igem.org/Team:DTU-Denmark-2/results/Proofofconcept/mammalian#Growth" class="h2"> Growth</a><br><br>
 
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<a href="https://2011.igem.org/Team:DTU-Denmark-2/results/Proofofconcept/mammalian#The U-2 OS cell line" class="h2"> The U-2 OS cell line</a><br><br>
 
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<a href="https://2011.igem.org/Team:DTU-Denmark-2/results/Proofofconcept/mammalian#Transient transfection" class="h2"> Transient transfection</a><br><br>
 
<a href="https://2011.igem.org/Team:DTU-Denmark-2/results/Proofofconcept/mammalian#Proof of concept" class="h1"> Proof of concept</a><br><br>
<a href="https://2011.igem.org/Team:DTU-Denmark-2/results/Proofofconcept/mammalian#Proof of concept" class="h1"> Proof of concept</a><br><br>
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<a href="https://2011.igem.org/Team:DTU-Denmark-2/results/Proofofconcept/mammalian#Device BBa_K678049" class="h2"> pJEJAM1 BBa_K678049</a><br><br>
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<a href="https://2011.igem.org/Team:DTU-Denmark-2/results/Proofofconcept/mammalian#Device BBa_K678049" class="h2"> pJEJAM1 <br>
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<a href="https://2011.igem.org/Team:DTU-Denmark-2/results/Proofofconcept/mammalian#Device BBa_K678050" class="h2"> pJEJAM2 BBa_K678050</a><br><br>
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BBa_K678049</a><br><br>
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<a href="https://2011.igem.org/Team:DTU-Denmark-2/results/Proofofconcept/mammalian#Device BBa_K678051" class="h2"> pJEJAM3 BBa_K678051</a><br><br>
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<a href="https://2011.igem.org/Team:DTU-Denmark-2/results/Proofofconcept/mammalian#Device BBa_K678050" class="h2"> pJEJAM2 <br>
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<a href="https://2011.igem.org/Team:DTU-Denmark-2/results/Proofofconcept/mammalian#Device BBa_K678052" class="h2"> pJEJAM4 BBa_K678052</a><br><br>
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BBa_K678050</a><br><br>
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<a href="https://2011.igem.org/Team:DTU-Denmark-2/results/Proofofconcept/mammalian#Device BBa_K678053" class="h2"> pJEJAM5 BBa_K678053</a><br><br>
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<a href="https://2011.igem.org/Team:DTU-Denmark-2/results/Proofofconcept/mammalian#Device BBa_K678051" class="h2"> pJEJAM3 <br>
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<a href="https://2011.igem.org/Team:DTU-Denmark-2/results/Proofofconcept/mammalian#Play'n'Mix" class="h2"> Play'n'Mix</a><br><br>
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BBa_K678051</a><br><br>
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<a href="https://2011.igem.org/Team:DTU-Denmark-2/results/Proofofconcept/mammalian#References" class="h1"> References</a><br><br>
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<a href="https://2011.igem.org/Team:DTU-Denmark-2/results/Proofofconcept/mammalian#Device BBa_K678052" class="h2"> pJEJAM4 <br>
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BBa_K678052</a><br><br>
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<a href="https://2011.igem.org/Team:DTU-Denmark-2/results/Proofofconcept/mammalian#Device BBa_K678053" class="h2"> pJEJAM5 <br>
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BBa_K678053</a><br><br>
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<a href="https://2011.igem.org/Team:DTU-Denmark-2/results/Proofofconcept/mammalian#Play'n'Mix" class="h2"> Mix'n'Play</a><br><br>
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<a name="Mammalian cells"></a><h2><b>Mammalian cells</b></h2>
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<a name="Proof of concept"></a><h1><b>Proof of concept</b></h1>
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Mammalian cells are higher eukaryotic cells derived from multicellular organisms. These cells contain a large number of membrane bound compartments like mitochondria, endoplasmatic reticulum, the Golgi apparatus etc. Eukaryotic cells also have a unique ability to process proteins post-translationally. Compared to microbes, mammalian cells are fragile, have a slow doubling time (app. 24h),require complex media and sophisticated fermentation setups for production processes (Mueller et al., 2003). Besides, microbial cells are excellent for production of different compounds like peptides and simple proteins such as insulin and growth hormones. So why use mammalian cells for industrial production at all?<br><br>
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Five different plasmids were assembled with the Plug ‘n’ Play standard in order to verify that the system functions in mammalian cells. To demonstrate how fast any vector of choice for the expression in mammalian cells can be assembled, we designed a reporter system as proof of concept. <br><br>
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Mammalian cell cultures represent a suitable and stabile gene expression system and are often used as cell factories for production of biopharmaceuticals. Heterologous protein expression in a suitable host is central in production of biopharmaceuticals, therefore mammalian cell cultures are  widely used for production of therapeutic proteins such as monoclonal antibodies, growth hormones, and cytokines used for a wide array of diseases.(Xie, Zhou, & Robinson, 2003) Heterologous proteins require complex post-translational modifications such as glycosylation, gamma-carboxylation, and site specific proteolysis, which only mammalian cells are capable of performing. Moreover, mammalian cells have the unique capability to authentically process, fold and modify secreted human proteins (Mueller et al., 2003). The effect of post-translationally modifications are protein stability, proper ligand binding, and the risk of immunogenicity is also reduced (4). Most of the therapeutic proteins approved and currently in development are post-translationally modified (5,5).
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The plasmids for proof of concept in mammalian cells were constructed with the strong constitutive <a href="http://partsregistry.org/wiki/index.php?title=Part:BBa_J52034">cytomegalovirus (CMV) promotor</a>, the <a href="http://partsregistry.org/wiki/index.php?title=Part:BBa_K678019">BGH terminator</a>, the <a href="http://partsregistry.org/wiki/index.php?title=Part:BBa_K678021">hygromycin marker cassette</a>, and the plasmid backbone <a href="http://partsregistry.org/Part:BBa_K678023">pMam</a>.
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However, the genetic tools used for constructing mammalian cells vectors are based on outworn methods, and since 60-70% of all recombinant protein pharmaceuticals are produced in mammalian cells, there is a desperate need for simpler and more efficient cloning techniques (Wurm, 2004).  
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Different genes encoding fluorescent proteins were used as the gene of interest, and the reporter system can easily be modified to be used for gene expression analysis. All transient transfections were performed in the human derived cell line U-2 OS, kindly provided by the Danish Cancer Society. For microscopy the transfected U-2 OS cells were fixed using 4% formaldehyde, and VECTASHIELD was added to prevent rapid loss of fluorescence while examining the cells with the confocal microscope.<br><br>
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We have proved that the Plug ‘n’ Play assembly standard can easily be applied for construction of mammalian expression vectors. Transfections and expression of the fluorescent proteins GFP, mCherry, YFP, and CFP were successfully conducted in U-2 OS cells. Furthermore, expression of GFP targeted to the peroxisomes of U-2 OS cells succeeded. Lastly it was shown that mammalian cells can be transfected with different fluorescent proteins simultaneously. <br><br>
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<a name="Growth"></a><h3><b> Growth</b></h3>
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This reporter system could be further developed enabling the localization of proteins to specific organelles. Such a system would allow the study of organelles and other compartments in real time.  
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Lots of different mammalian cell lines have been derived.Mammalian cells can grow in suspension or as adherent cells
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They require complex media
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<a name="The U-2 OS cell line"></a><h3><b>The U-2 OS cell line</b></h3>
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The U-2 OS cell line, originally known as the 2T line, is an immortalized human-derived cell line that was established in 1964. The original cells were taken from bone tissue of the tibia of a 15 year old girl suffering from osteosarcoma. An immortalized cell line has acquired ability to proliferate indefinitely through either random mutation or modifications such as artificial expression of the telomerase gene. Several cell lines are well established as representatives of certain cell types. U-2 OS cells show epithelial adherent morphology, and no viruses have been detected in the cell line. In comparison, the HeLa cell line contain the well known HPV virus. They are also very good-looking in a confocal microscope, and therefore U-2 OS was chosen for proof of concept of Plug ‘n’ Play in mammalian cells.
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<a name="Transient transfection"></a><h3><b>Transient transfection</b></h3>
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Transient expression is the ability to express a heterologous DNA during a short period of time, which allows fast production of a desired protein. A high copy number of plasmids are introduced into the cells, and expression may be transitory over a period until the DNA is lost from the population. This allows protein characterization or to verify the integrity, functionality, and the efficiency of different recombinant vectors. Production of large amount of recombinant protein has been reported for transient expression system on large scale. A small number of the transfected cells may incorporate the exogenous DNA into their genome by recombination leading to a stable transfection of a gene (Bollati-Fogolín & Comini, 2008). <br>
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The success of transfections depends on several factors that must be taken intoaccount: <br>
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<dd>1. the transfectability and physiology of the cell line</dd>
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<dd>4. the size of the expression cassette and the quality of the DNA introduced</dd>
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<dd>5. the compatibility of transfection method and the cell line</dd>
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<dd>6. the use of assay for detection of recombinant protein</dd>
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<dd>7. the presence of serum and/or antibiotics in the culture medium</dd>
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The mammalian expression vectors have a multiple cloning site (MCS). The gene of interest is therefore required to hold restriction sites compatible with the expression vector and the insertion of the gene is achieve by ligase. The method is often cumbersome in construction of the expression vector. Furthermore, the integration of the gene of interest in the expression vector by restriction enzymes and ligases have low efficiency as well as provide high number of false-positive (Bollati-Fogolín & Comini, 2008).<br>
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<a name="Proof of concept"></a><h3><b>Proof of concept</b></h3>
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To demonstrate how fast any vector of choice for the expression in mammalian cells can be assembled we chose to design a reporter system as proof of concept. This system comprises a backbone plasmid that allows for the amplification in and selection of E. coli, the strong constitutive cytomegalovirus (CMV) promoter, a gene module consisting of a gene encoding a fluorescence protein or a gene encoding a fluorescence protein and a localization signal, the BGH terminator and the hygromycin marker cassette. This reporter system can easily be modified and used for gene expression studies. Furthermore we designed a vector for localization of GFP to the peroxisomes, which for instance could be used to monitor movement and metabolism. The idea is to develop this reporter system so that proteins can be localized to organelles and other subcellular compartments allowing for the study of organelles in real time. We also showed that cells can be transfected with different fluorescence proteins at the same time. Further development of this system would allow targeting of different compartments with different fluorescence proteins at the same time. The U-2 OS cells were transiently transfected with the different plasmids constructed. The cells were fixed using 4% formaldehyde, and VECTASHIELD was added to prevent rapid loss of fluorescence while examining the cells microscopically. Visualization was performed with a confocal microscope.  
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<a name="Device BBa_K678049"></a><h2>pJEJAM1 BBa_K678049</h2>
<a name="Device BBa_K678049"></a><h2>pJEJAM1 BBa_K678049</h2>
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<a href="http://partsregistry.org/wiki/index.php?title=Part:BBa_K678049">BBa_K678049</a> is a plasmid intended for transient transfection of mammalian cells. The expression of the green fluorescence protein is under the control of the strong constitutive CMV promoter, which can be seen in the figure below.  
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<a href="http://partsregistry.org/wiki/index.php?title=Part:BBa_K678049">pJEJAM1</a> is a plasmid intended for transient transfection of mammalian cells. The expression of the green fluorescent protein (GFP) is under the control of the strong constitutive CMV promoter, which can be seen in the figure below.  
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<td>U-2 OS cells transiently transfected with plasmid  <a href="http://partsregistry.org/wiki/index.php?title=Part:BBa_K678049">BBa_K678049</a> expressing GFP. This vector provides a good expression and homogenous distribution of GFP. The white bar has a length of 20μm. </td>
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<td>U-2 OS cells transiently transfected with <a href="http://partsregistry.org/wiki/index.php?title=Part:BBa_K678049">pJEJAM1</a> expressing GFP. This plasmid provides a good expression and homogenous distribution of GFP. The white bar has a length of 20μm. </td>
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<td>U-2 OS cells transiently transfected with pJEJAM1 expressing GFP. This vector provides a good expression and homogenous distribution of GFP. The white bar has a length of 20μm. </td>
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<td>U-2 OS cells transiently transfected with <a href="http://partsregistry.org/wiki/index.php?title=Part:BBa_K678049">pJEJAM1</a> expressing GFP. This plasmid provides a good expression and homogenous distribution of GFP. The white bar has a length of 20μm. </td>
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<a name="Device BBa_K678050"></a><h2>pJEJAM2 BBa_K678050</h2>
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<a href="http://partsregistry.org/wiki/index.php?title=Part:BBa_K678050">pJEJAM2</a> is a plasmid intended for transient transfection of mammalian cells. The expression of GFP is under the control of the strong constitutive CMV promoter (see the figure below). The peroxisomal targeting signal PTS1 is directly fused to the C-terminal of GFP, this sequence should ensure the localization of GFP to the peroxisomes of the cell. Although the microscopy shows GFP distributed in points, further analysis are necessary to confirm that GFP is in fact is targeted to the peroxisomes.
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<a name="Device BBa_K678049"></a><h2>pJEJAM2 BBa_K678050</h2>
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<a href="http://partsregistry.org/wiki/index.php?title=Part:BBa_K678050">BBa_K678050</a> is a plasmid intended for transient transfection of mammalian cells. The expression of the green fluorescence protein (GFP) is under the control of the strong constitutive CMV promoter (see the figure below. The peroxisomal targeting signal PTS1 is directly fused to the C-terminal of GFP, this sequence ensures the localization of GFP to the peroxisomes of the cell.  
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<td>U-2 OS cells transiently transfected with plasmid <a href="http://partsregistry.org/wiki/index.php?title=Part:BBa_K678049">BBa_K678050</a> expressing GFP localized to the peroxisomes. As can be seen on the picture this vector as intended localizes GFP to the peroxisomes of the cells. The white bar has a length of 30μm. </td>
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<td>U-2 OS cells transiently transfected with <a href="http://partsregistry.org/wiki/index.php?title=Part:BBa_K678050">pJEJAM2</a> expressing GFP localized to the peroxisomes. As can be seen on the picture this vector most likely localizes GFP to the peroxisomes of the cells. The white bar has a length of 30μm. </td>
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<a name="Device BBa_K678051"></a><h2>pJEJAM3 BBa_K678051</h2>
<a name="Device BBa_K678051"></a><h2>pJEJAM3 BBa_K678051</h2>
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<a href="http://partsregistry.org/wiki/index.php?title=Part:BBa_K678051">BBa_K678051</a> is a plasmid intended for transient transfection of mammalian cells. The expression of the yellow fluorescence protein (YFP), is under the control of the strong constitutive CMV promoter (see the figure below).  
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<a href="http://partsregistry.org/wiki/index.php?title=Part:BBa_K678051">pJEJAM3</a> is a plasmid intended for transient transfection of mammalian cells. The expression of the yellow fluorescent protein (YFP), is under the control of the strong constitutive CMV promoter (see the figure below).  
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<td>U-2 OS cells transiently transfected with plasmid <a href="http://partsregistry.org/wiki/index.php?title=Part:BBa_K678051">BBa_K678051</a> expressing YFP. This vector provides a good expression and homogenous distribution of YFP. The white bar has a length of 40μm. </td>
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<td>U-2 OS cells transiently transfected with <a href="http://partsregistry.org/wiki/index.php?title=Part:BBa_K678051">pJEJAM4</a> expressing YFP. This vector provides a good expression and homogenous distribution of YFP. The white bar has a length of 40μm. </td>
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<td>U-2 OS cells transiently transfected with plasmid <a href="http://partsregistry.org/wiki/index.php?title=Part:BBa_K678051">BBa_K678051</a> expressing YFP. This vector provides a good expression and homogenous distribution of YFP. The white bar has a length of 30μm. </td>
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<td>U-2 OS cells transiently transfected with <a href="http://partsregistry.org/wiki/index.php?title=Part:BBa_K678051">pJEJAM4</a> expressing YFP. This vector provides a good expression and homogenous distribution of YFP. The white bar has a length of 30μm. </td>
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<a name="Device BBa_K678052"></a><h2>pJEJAM4 BBa_K678052</h2>
<a name="Device BBa_K678052"></a><h2>pJEJAM4 BBa_K678052</h2>
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<a href="http://partsregistry.org/wiki/index.php?title=Part:BBa_K678052">BBa_K678052</a> is a plasmid intended for transient transfection of mammalian cells. The expression of mCherry, a red fluorescence protein, is under the control of the strong constitutive CMV promoter (see the figure below).  
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<a href="http://partsregistry.org/wiki/index.php?title=Part:BBa_K678052">pJEJAM4</a> is a plasmid intended for transient transfection of mammalian cells. The expression of mCherry, a red fluorescent protein, is under the control of the strong constitutive CMV promoter (see the figure below).  
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<td>U-2 OS cells transiently transfected with plasmid <a href="http://partsregistry.org/wiki/index.php?title=Part:BBa_K678052">BBa_K678052</a> expressing mCherry. This vector provides a good expression and homogenous distribution of mCherry. The white bar has a length of 70μm. </td>
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<td>U-2 OS cells transiently transfected with <a href="http://partsregistry.org/wiki/index.php?title=Part:BBa_K678052">pJEJAM4</a> expressing mCherry. This vector provides a good expression and homogenous distribution of mCherry. The white bar has a length of 70μm. </td>
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<td>U-2 OS cells transiently transfected with plasmid <a href="http://partsregistry.org/wiki/index.php?title=Part:BBa_K678052">BBa_K678052</a> expressing mCherry. This vector provides a good expression and homogenous distribution of mCherry. The white bar has a length of 50μm. </td>
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<td>U-2 OS cells transiently transfected with <a href="http://partsregistry.org/wiki/index.php?title=Part:BBa_K678052">pJEJAM4</a> expressing mCherry. This vector provides a good expression and homogenous distribution of mCherry. The white bar has a length of 50μm. </td>
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<a name="Device BBa_K678053"></a><h2>pJEJAM5 BBa_K678053</h2>
<a name="Device BBa_K678053"></a><h2>pJEJAM5 BBa_K678053</h2>
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<a href="http://partsregistry.org/wiki/index.php?title=Part:BBa_K678053">BBa_K678053</a> is a plasmid intended for transient transfection of mammalian cells. The expression of cyan fluorescence protein (CFP), is under the control of the strong constitutive CMV promoter (see the figure below).  
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<a href="http://partsregistry.org/wiki/index.php?title=Part:BBa_K678053">pJEJAM5</a> is a plasmid intended for transient transfection of mammalian cells. The expression of cyan fluorescent protein (CFP), is under the control of the strong constitutive CMV promoter (see the figure below).  
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<td>U-2 OS cells transiently transfected with plasmid <a href="http://partsregistry.org/wiki/index.php?title=Part:BBa_K678053">BBa_K678053</a> expressing CFP. This vector provides a good expression and homogenous distribution of CFP. The white bar has a length of 70μm. </td>
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<td>U-2 OS cells transiently transfected with <a href="http://partsregistry.org/wiki/index.php?title=Part:BBa_K678053">pJEJAM5</a> expressing CFP. This vector provides a good expression and homogenous distribution of CFP. The white bar has a length of 70μm. </td>
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<td>U-2 OS cells transiently transfected with plasmid pJEJAM5 expressing CFP. This vector provides a good expression and homogenous distribution of CFP. The white bar has a length of 50μm.  </td>
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<td>U-2 OS cells transiently transfected with <a href="http://partsregistry.org/wiki/index.php?title=Part:BBa_K678053">pJEJAM5</a> expressing CFP. This vector provides a good expression and homogenous distribution of CFP. The white bar has a length of 50μm.  </td>
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<a name="Play'n'Mix"></a><h2>Mix'n'Play </h2>
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<a name="Play'n'Mix"></a><h2>Play'n'Mix</h2>
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Mammalian cells can be transiently transfected with several plasmids at once, allowing the simultaneous expression of different fluorescence proteins. The pictures below demonstrate different combinations of fluorescent proteins.
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Mammalian cells can be transiently transfected with several plasmids at once, allowing the simultaneous expression of different fluorescent proteins. The pictures below demonstrate different combinations of fluorescent proteins.
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<td>U-2 OS cells transiently transfected with plasmids <a href="http://partsregistry.org/wiki/index.php?title=Part:BBa_K678050">BBa_K678050</a> and <a href="http://partsregistry.org/wiki/index.php?title=Part:BBa_K678053">BBa_K678053</a> expressing GFP localized to the peroxisomes and CFP. The white bar has a length of 30μm. </td>
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<td>U-2 OS cells transiently transfected with <a href="http://partsregistry.org/wiki/index.php?title=Part:BBa_K678050">pJEJAM2</a> and <a href="http://partsregistry.org/wiki/index.php?title=Part:BBa_K678053">pJEJAM5</a> expressing GFP localized to the peroxisomes and CFP, respectively. The white bar has a length of 30μm. </td>
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<td>U-2 OS cells transiently transfected with plasmids <a href="http://partsregistry.org/wiki/index.php?title=Part:BBa_K678049">BBa_K678049</a> and <a href="http://partsregistry.org/wiki/index.php?title=Part:BBa_K678053">BBa_K678053</a> expressing GFP and CFP. The white bar has a length of 30μm. </td>
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<td>U-2 OS cells transiently transfected with <a href="http://partsregistry.org/wiki/index.php?title=Part:BBa_K678049">pJEJAM1</a> and <a href="http://partsregistry.org/wiki/index.php?title=Part:BBa_K678053">pJEJAM5</a> expressing GFP and CFP, respectively. The white bar has a length of 30μm. </td>
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<td>U-2 OS cells transiently transfected with plasmids <a href="http://partsregistry.org/wiki/index.php?title=Part:BBa_K678049">BBa_K678049</a> and <a href="http://partsregistry.org/wiki/index.php?title=Part:BBa_K678052">BBa_K678052</a> expressing GFP and mCherry. The white bar has a length of 70μm. </td>
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<td>U-2 OS cells transiently transfected with <a href="http://partsregistry.org/wiki/index.php?title=Part:BBa_K678049">pJEJAM1</a> and <a href="http://partsregistry.org/wiki/index.php?title=Part:BBa_K678052">pJEJAM4</a> expressing GFP and mCherry, respectively. The white bar has a length of 70μm. </td>
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<td>U-2 OS cells transiently transfected with plasmids <a href="http://partsregistry.org/wiki/index.php?title=Part:BBa_K678052">BBa_K678052</a> and <a href="http://partsregistry.org/wiki/index.php?title=Part:BBa_K678053">BBa_K678053</a> expressing YFP and CFP. The white bar has a length of 40μm. </td>
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<td>U-2 OS cells transiently transfected with <a href="http://partsregistry.org/wiki/index.php?title=Part:BBa_K678052">pJEJAM3</a> and <a href="http://partsregistry.org/wiki/index.php?title=Part:BBa_K678053">pJEJAM5</a> expressing YFP and CFP, respectively. The white bar has a length of 40μm. </td>
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<a name="References"></a><h1><b>References</b></h1>
 
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(1) Hesse, F., Wagner, R. (2000). Developments and improvements in the manufacturing of human therapeutics with mammalian cell cultures. TIBTECH, 18, 173-180.<br><br>
 
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(2) Global Biopharmaceutical Market Report (2010-2015). (2010). The International Market Analysis Research and Consulting Group.<br><br>
 
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(3) Xie, L., Zhou, W., Robinson, D. (2003). Protein production by large-scale mammalian cell culture. S.C. Makrides (Ed.) Gene Transfer and Expression in Mammalian Cells. Elsevier Science B.V.<br><br>
 
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(4) Browne, SM., Al-Rubeai, M. (2007). Selection methods for high-producing mammalian cell lines. TRENDS in Biotechnology, 25, 425-432.<br><br>
 
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(5) Walsh, W., Jefferis, R. (2006). Post-translational modifications in the context of therapeutic proteins. Nature Biotechnology, 24, 1241-1252.<br><br>
 
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Latest revision as of 00:24, 22 September 2011




Proof of concept in mammalian cells



Proof of concept

Five different plasmids were assembled with the Plug ‘n’ Play standard in order to verify that the system functions in mammalian cells. To demonstrate how fast any vector of choice for the expression in mammalian cells can be assembled, we designed a reporter system as proof of concept.

The plasmids for proof of concept in mammalian cells were constructed with the strong constitutive cytomegalovirus (CMV) promotor, the BGH terminator, the hygromycin marker cassette, and the plasmid backbone pMam. Different genes encoding fluorescent proteins were used as the gene of interest, and the reporter system can easily be modified to be used for gene expression analysis. All transient transfections were performed in the human derived cell line U-2 OS, kindly provided by the Danish Cancer Society. For microscopy the transfected U-2 OS cells were fixed using 4% formaldehyde, and VECTASHIELD was added to prevent rapid loss of fluorescence while examining the cells with the confocal microscope.

We have proved that the Plug ‘n’ Play assembly standard can easily be applied for construction of mammalian expression vectors. Transfections and expression of the fluorescent proteins GFP, mCherry, YFP, and CFP were successfully conducted in U-2 OS cells. Furthermore, expression of GFP targeted to the peroxisomes of U-2 OS cells succeeded. Lastly it was shown that mammalian cells can be transfected with different fluorescent proteins simultaneously.

This reporter system could be further developed enabling the localization of proteins to specific organelles. Such a system would allow the study of organelles and other compartments in real time.



pJEJAM1 BBa_K678049

pJEJAM1 is a plasmid intended for transient transfection of mammalian cells. The expression of the green fluorescent protein (GFP) is under the control of the strong constitutive CMV promoter, which can be seen in the figure below.


U-2 OS cells transiently transfected with pJEJAM1 expressing GFP. This plasmid provides a good expression and homogenous distribution of GFP. The white bar has a length of 20μm. U-2 OS cells transiently transfected with pJEJAM1 expressing GFP. This plasmid provides a good expression and homogenous distribution of GFP. The white bar has a length of 20μm.


pJEJAM2 BBa_K678050

pJEJAM2 is a plasmid intended for transient transfection of mammalian cells. The expression of GFP is under the control of the strong constitutive CMV promoter (see the figure below). The peroxisomal targeting signal PTS1 is directly fused to the C-terminal of GFP, this sequence should ensure the localization of GFP to the peroxisomes of the cell. Although the microscopy shows GFP distributed in points, further analysis are necessary to confirm that GFP is in fact is targeted to the peroxisomes.


U-2 OS cells transiently transfected with pJEJAM2 expressing GFP localized to the peroxisomes. As can be seen on the picture this vector most likely localizes GFP to the peroxisomes of the cells. The white bar has a length of 30μm.


pJEJAM3 BBa_K678051

pJEJAM3 is a plasmid intended for transient transfection of mammalian cells. The expression of the yellow fluorescent protein (YFP), is under the control of the strong constitutive CMV promoter (see the figure below).


U-2 OS cells transiently transfected with pJEJAM4 expressing YFP. This vector provides a good expression and homogenous distribution of YFP. The white bar has a length of 40μm. U-2 OS cells transiently transfected with pJEJAM4 expressing YFP. This vector provides a good expression and homogenous distribution of YFP. The white bar has a length of 30μm.


pJEJAM4 BBa_K678052

pJEJAM4 is a plasmid intended for transient transfection of mammalian cells. The expression of mCherry, a red fluorescent protein, is under the control of the strong constitutive CMV promoter (see the figure below).



U-2 OS cells transiently transfected with pJEJAM4 expressing mCherry. This vector provides a good expression and homogenous distribution of mCherry. The white bar has a length of 70μm. U-2 OS cells transiently transfected with pJEJAM4 expressing mCherry. This vector provides a good expression and homogenous distribution of mCherry. The white bar has a length of 50μm.


pJEJAM5 BBa_K678053

pJEJAM5 is a plasmid intended for transient transfection of mammalian cells. The expression of cyan fluorescent protein (CFP), is under the control of the strong constitutive CMV promoter (see the figure below).


U-2 OS cells transiently transfected with pJEJAM5 expressing CFP. This vector provides a good expression and homogenous distribution of CFP. The white bar has a length of 70μm. U-2 OS cells transiently transfected with pJEJAM5 expressing CFP. This vector provides a good expression and homogenous distribution of CFP. The white bar has a length of 50μm.


Mix'n'Play

Mammalian cells can be transiently transfected with several plasmids at once, allowing the simultaneous expression of different fluorescent proteins. The pictures below demonstrate different combinations of fluorescent proteins.

U-2 OS cells transiently transfected with pJEJAM2 and pJEJAM5 expressing GFP localized to the peroxisomes and CFP, respectively. The white bar has a length of 30μm. U-2 OS cells transiently transfected with pJEJAM1 and pJEJAM5 expressing GFP and CFP, respectively. The white bar has a length of 30μm.
U-2 OS cells transiently transfected with pJEJAM1 and pJEJAM4 expressing GFP and mCherry, respectively. The white bar has a length of 70μm. U-2 OS cells transiently transfected with pJEJAM3 and pJEJAM5 expressing YFP and CFP, respectively. The white bar has a length of 40μm.