Name: the c-fos protein immunohistological detection: a useful tool as a marker of central pathways involved in specific physiological responses in vivo and ex vivo
Uploaded: 2016-04-25T14:00:00
Description: Watch this Scientific Journal Video about The c-FOS Protein Immunohistological Detection: A Useful Tool As a Marker of Central Pathways Involved in Specific Physiological Responses In Vivo and Ex Vivo

The University Paris 13 supported this work. ASPT was supported by a University Paris 13 fellowship and the "Association Fran&#231;aise pour le Syndrome d'Ondine". FJ was supported by a Laboratory of Excellence GR-Ex fellowship. The GR-Ex (ref ANR-11-LABX-0051) is funded by the program "Investissement d'avenir" of the French National Research agency (ref ANR-11-IDEX-0005-02).

Note: c-FOS detection is a standardized procedure involving several steps (Figure 1). All experiments were performed on rats or mice. Experimental protocols were approved by the Ethics Committee in Animal Experiment Charles Darwin (Ce5/2011/05), done in accordance with the European Communities Council Directive of September 22, 2010 (2010/63/EU) for animal care, and conducted in accordance with French laws for animal care.
1. Preparation of Solutions
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	<li>Prepare 0.2 M ...

<ol>
	<li>Curran, T., Teich, N. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Identification+of+a+39,000-dalton+protein+in+cells+transformed+by+the+FBJ+murine+osteosarcoma+virus.">Identification of a 39,000-dalton protein in cells transformed by the FBJ murine osteosarcoma virus.</a> Virology. 116, 221-235 (1982).</li><li>Curran, T., MacConnell, W. P., van Straaten, F., Verma, I. 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C-fos is an immediate early gene, and the detection of its product, the c-FOS protein, is classically used to identify neuronal populations involved in specific respiratory responses in vivo11,13,25,28 and ex vivo16-18,27,32,33.
Critical Steps Within the Protocol
Be careful during the perfusion step. The 4% PFA solution must be well prepared and the fixation and post-fixation steps m...

The c-fos gene was identified for the first time at the beginning of 19801,2 and its product was characterized in 1984 as a nuclear protein having gene-activator properties3,4. It participates in long-term mechanisms associated with neuron stimulation. Indeed, changes in&#160;neuronal activity lead to second messenger signaling cascades that induce the expression of the immediate early gene c-fos, which induces the production of the transcription factor c-FOS. The latter initiates the expression of late genes and thus participates in&#160;adaptive responses of the nervous system to many different types of stimuli4. Thus, since the end of 19805,6, c-FOS protein detection has been frequently used to study the effects of exogenous factors on gene transcription in general4 and on the activity of the central nervous system (CNS) for mapping out neuronal pathways involved in different physiological conditions.
Basal c-fos expression has been studied in various species including mice, rat, cat, monkey, and human4. Thereby, the kinetics of its expression is relatively well known. The transcription activation is rapid (5 to 20 min)7,8, and the mRNA accumulation reaches a maximum between 30 and 45 min after the onset of stimulation9 and declines with a short half-life of 12 min. The c-FOS protein synthesis follows mRNA accumulation and could be detected by immunohistochemistry at&#160;20 to 90 min&#160;post stimulation6.
Analysis of c-fos expression is classically used in in vivo studies to identify the central respiratory network involved in the ventilatory responses to hypoxia or hypercapnia10-14. More recently, this tool was also used in ex vivo brainstem preparations to explore central respiratory network adaptations to hypoxia or hypercapnia15-18. Indeed, these preparations generate a rhythmic activity classically assimilated to the central respiratory drive19. Thus, this type of preparation has the advantage of being completely deafferented, and therefore, results regarding c-fos expression only reflect the consequences of a central stimulation without any intervention of peripheral structures.
The c-FOS detection could be made by immunohistochemical or immunohistofluorescence approaches. Indirect immunodetection necessitates the use of a primary antibody against c-FOS and a secondary antibody directed against the species in which the primary antibody was produced. For the immunohistochemical method, the secondary antibody is conjugated with an enzyme (peroxidase, for example) that acts on a substrate (H2O2 for the peroxidase). The product of the enzymatic reaction is developed by a chromogen (3.3-diaminobenzidine tetrahydrochloride), which stains it and can be observed under light microscopy. The reaction could be reinforced using nickel ammonium sulphate. These methods allow the detection of actives neurons during different physiological challenges and therefore the identification and/or the mapping of peripheral and central pathways involved in the consecutive physiological responses.

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			<td height="21" style="height:21px;width:216px;">Cell culture plate 12-Well</td>
			<td style="width:71px;">Costa</td>
			<td style="width:119px;">35/3</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="106">
			<td height="106" style="height:107px;width:216px;">15 mm Netwell inserts with mesh polyester membrane</td>
			<td style="width:71px;">Corning</td>
			<td style="width:119px;">3477</td>
			<td style="width:167px;">The 15mm diameter well inserts have 74&#181;m polyester mesh bottoms attached to polystyrene inserts</td>
		</tr>
		<tr height="85">
			<td height="85" style="height:85px;width:216px;">primary antibody (rabbit polyclonal antibody against the c-Fos protein)</td>
			<td style="width:71px;">Santa Cruz Biotechnology</td>
			<td style="width:119px;">sc-52</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;width:216px;">Vectastain Elite ABC KIT&#160;</td>
			<td rowspan="2" style="width:71px;">Vector laboratories</td>
			<td rowspan="2" style="width:119px;">PK-6101</td>
			<td rowspan="2" style="width:167px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">(Rabbit IgG-secondary antibody)</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">NaH2PO4*2H2O</td>
			<td style="width:71px;">Sigma</td>
			<td style="width:119px;">71505</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Na2HPO4</td>
			<td style="width:71px;">Sigma</td>
			<td style="width:119px;">S7907</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Paraformaldehyde</td>
			<td style="width:71px;">Sigma</td>
			<td style="width:119px;">P6148</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">NaOH 0.1N</td>
			<td style="width:71px;">Sigma</td>
			<td style="width:119px;">43617</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Polyvinyl-Pyrrolidone</td>
			<td style="width:71px;">Sigma</td>
			<td style="width:119px;">PVP-360</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Sucrose</td>
			<td style="width:71px;">Sigma</td>
			<td style="width:119px;">S7903</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">NaCl</td>
			<td style="width:71px;">Sigma</td>
			<td style="width:119px;">S7653</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Ethylene-glycol</td>
			<td style="width:71px;">Sigma</td>
			<td style="width:119px;">33068</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Triton X100</td>
			<td style="width:71px;">Sigma</td>
			<td style="width:119px;">T8787</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Trisma HCl</td>
			<td style="width:71px;">Sigma</td>
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		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Trisma Base</td>
			<td style="width:71px;">Sigma</td>
			<td style="width:119px;">T1503</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">3.3-diaminobenzidine tetrahydrochloride&#160;</td>
			<td style="width:71px;">Rockland</td>
			<td style="width:119px;">DAB50</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Nickel ammonium sulphate</td>
			<td style="width:71px;">Alfa Aesar</td>
			<td style="width:119px;">12519</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">H2O2</td>
			<td style="width:71px;">Sigma</td>
			<td style="width:119px;">H1009</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Xylene</td>
			<td style="width:71px;">Sigma</td>
			<td style="width:119px;">33817</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Entellan Neo</td>
			<td style="width:71px;">Merck Millipore</td>
			<td style="width:119px;">107961</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Slide&#160;</td>
			<td style="width:71px;">Thermo-scientific</td>
			<td style="width:119px;">1014356190</td>
			<td style="width:167px;">Superfrost ultraplus</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Cover glass</td>
			<td style="width:71px;">Thermo-scientific</td>
			<td style="width:119px;">Q10143263NR1</td>
			<td style="width:167px;">24 x 60mm</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">BSA</td>
			<td style="width:71px;">Sigma</td>
			<td style="width:119px;">A2153</td>
			<td style="width:167px;"></td>
		</tr>
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</table>

the c-fos protein immunohistological detection: a useful tool as a marker of central pathways involved in specific physiological responses in vivo and ex vivo

Many studies seek to identify and map the brain regions involved in specific physiological regulations. The proto-oncogene c-fos, an immediate early gene, is expressed in neurons in response to various stimuli. The protein product can be readily detected with immunohistochemical techniques leading to the use of c-FOS detection to map groups of neurons that display changes in their activity. In this article, we focused on the identification of brainstem neuronal populations involved in the ventilatory adaptation to hypoxia or hypercapnia. Two approaches were described to identify involved neuronal populations in vivo in animals and ex vivo in deafferented brainstem preparations. In vivo, animals were exposed to hypercapnic or hypoxic gas mixtures. Ex vivo, deafferented preparations were superfused with hypoxic or hypercapnic artificial cerebrospinal fluid. In both cases, either control in vivo animals or ex vivo preparations were maintained under normoxic and normocapnic conditions. The comparison of these two approaches allows the determination of the origin of the neuronal activation i.e., peripheral and/or central. In vivo and ex vivo, brainstems were collected, fixed, and sliced into sections. Once sections were prepared, immunohistochemical detection of the c-FOS protein was made in order to identify the brainstem groups of cells activated by hypoxic or hypercapnic stimulations. Labeled cells were counted in brainstem respiratory structures. In comparison to the control condition, hypoxia or hypercapnia increased the number of c-FOS labeled cells in several specific brainstem sites that are thus constitutive of the neuronal pathways involved in the adaptation of the central respiratory drive.

The c-FOS detection is a useful tool that allows identifying groups of activated cells under specific conditions such as hypoxia and hypercapnia in vivo (Figure 2A) or in situations that mimic&#160;these conditions ex vivo (Figure 2B). In vivo, newborn, young, or adult rodents were placed in an airtight box in which the gaseous environment is continually renewed by a gas mixture with a composition precisely defined for 30 to 180...

Watch this Scientific Journal Video about The c-FOS Protein Immunohistological Detection: A Useful Tool As a Marker of Central Pathways Involved in Specific Physiological Responses In Vivo and Ex Vivo

The c-FOS Protein Immunohistological Detection: A Useful Tool As a Marker of Central Pathways Involved in Specific Physiological Responses In Vivo and Ex Vivo

Here, we present a protocol based on c-FOS protein immunohistological detection, a classical technique used for the identification of neuronal populations involved in specific physiological responses in vivo and ex vivo.

The c-FOS Protein Immunohistological Detection: A Useful Tool As a Marker of Central Pathways Involved in Specific Physiological Responses In Vivo and Ex Vivo

Many studies seek to identify and map the brain regions involved in specific physiological regulations. The proto-oncogene c-fos, an immediate early gene, ...

The overall goal of this immunohistochemical detection against c-FOS protein is to assess the neuronal activity in brain tissues. This method can help answer our key questions in the neurophysological field such as brain mapping and identification of brain regions involved in specific physiological regulations. The main advantage of this technique is that c-FOS gene has a low expression in the absence of stimulation, which allows easier quantification of neuronal activity in our test simulation.To begin this procedure, wash the coronal brain stem sections for 10 minutes with 0.1 molar PBS at room temperature. Repeat the wash three times. Next, suppress the endogenous peroxidase activity by incubating the sections with 3%hydrogen peroxide in 0.1 molar PBS for 30 minutes at room temperature.Then, wash the sections for 10 minutes with 0.1 molar PBS at room temperature and repeat three times. Block nonspecific binding sites by incubating the coronal sections with 2%goat serum in PBST for one hour at room temperature. Subsequently, incubate the sections with a rapid polyclonal antibody against the c-FOS protein in PBST with 0.25%bovine serum albumin for 48 hours at four degrees Celsius.In this step, wash the sections with 0.1 molar PBS for 10 minutes at room temperature and repeat the procedure three times. Next, incubate the coronal sections for one hour at room temperature with a biotinylated goat anti-rabbit antibody in PBST with 0.25%bovine serum albumin. After one hour, wash the sections for 10 minutes with PBST at room temperature and repeat three times.Then, incubate the coronal sections for one hour with an avidin biotin peroxidase complex in PBST. Subsequently, wash the sections with PBST at room temperature for 10 minutes and repeat two more times. Then, wash the sections for 10 minutes with 05 molar Tris buffer at room temperature and repeat the wash two more times.Next, incubate the coronal sections with DAB, nickel ammonium sulfate, and hydrogen peroxide in 05 molar Tris buffer at room temperature. Add 17 microliters of hydrogen peroxide to the remaining Tris buffer. When the staining intensity is optimal, stop the reaction by washing the sections with 0.1 molar PBS for 10 minutes at room temperature, and repeat the wash four times.Then, wash the sections with distilled water. Now, mount the sections serially on the slides by carefully spreading them in rostrocaudal order on the slides with a brush. After that, let the sections air dry and clearly label the slides according to the samples.Then, dehydrate the sections by immersing the slides in an absolute alcohol bath for 30 seconds at room temperature, and repeat the procedure twice. Next, immerse the slides in a xylene bath for three minutes at room temperature and repeat twice. Subsequently, apply five drops of mounting medium on each slide.Place cover glass on them and avoid forming air bubbles. Let the slides air dry for 48 hours. Shown here is a drawing of a section of the medula oblangata.The dotted area shows the commissural and median parts of the nucleus tractus solitarius. The rectangle indicates the region that photomicrographs were taken. These are the photomicrographs of c/mNTS in the condition of normoxia or under hypoxia.The black arrows show c-FOS-positive cells. Here is a histogram showing the mean number of c-FOS-positive cells per section in c/mNTS in the condition of normoxia or under hypoxia. The number of c-FOS-positive cells was significantly higher in the condition of hypoxia than that of normoxia.After watching this video, you should have a good understanding of how to use the c-FOS immunohistochemical detection as a marker of central pathway involved in specific physiological stimulation.

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Research

JoVE Journal

Biology

Single Cell Electroporation in vivo within the Intact Developing Brain

Single-cell electroporation (SCE) is a specialized technique allowing the delivery of DNA or other macromolecules into individual cells within intact tissue, including in vivo preparations. The distinct advantage of this technique is that experimental manipulations may be performed on individual cells while leaving the surrounding tissue unaltered, thereby distinguishing cell-autonomous effects from those resulting from global treatments. When combined with advanced in vivo imaging techniques, SCE of fluorescent markers permits direct visualization of cellular morphology, cell growth, and intracellular events over timescales ranging from seconds to days. While this technique is used in a variety of in vivo and ex vivo preparations, we have optimized this technique for use in Xenopus laevis tadpoles. In this video article, we detail the procedure for SCE of a fluorescent dye or plasmid DNA into neurons within the intact brain of the albino Xenopus tadpole. We also discuss methods to optimize yield, and show examples of live two-photon fluorescence imaging of neurons fluorescently labeled by SCE.

Single-cell electroporation (SCE) is a specialized technique allowing delivery of DNA or other macromolecules into individual cells within intact tissue, including in vivo preparations. Here we detail the procedure for SCE of a fluorescent dye or plasmid DNA into neurons within the intact brain of the Xenopus laevis tadpole.

Single-cell electroporation (SCE) is a specialized technique allowing the delivery of DNA or other macromolecules into individual cells within intact ...

Method for Culture of Early Chick Embryos ex vivo (New Culture)

The chick embryo is a valuable tool in the study of early embryonic development. Its transparency, accessibility and ease of manipulation, make it an ideal tool for studying  the formation and patterning of brain, neural tube, somite and heart primordia. Applications of chick embryo culture include electroporation of DNA or RNA constructs in order to analyze gene function, grafts of growth factor coated beads such as FGFs and BMPs , as well as whole mount in situ hybridization and immunohistochemistry. This video demonstrates the different steps in chick embryo culture; First, the embryo is explanted in saline. Then, the embryo is centered on a glass ring. The membranes surrounding the embryo are lifted along the walls of the ring. The ring is then placed in a culture dish containing a pool of albumine. The culture dish is sealed and placed in a humid chamber, where the embryo is cultured for up to 24 hrs. Finally, the embryo is removed from the ring, fixed and processed for further applications. A troubleshooting guide is also presented.

Method for Culture of Early Chick Embryos ex vivo New Culture

This video demonstrates New culture, a method by which chick embryos are cultured outside the egg for up to 24 hr. This method enables one to study early development (primitive streak to 14 som.), a period corresponding to E7-9 in mouse. Applications of this technique include electroporation, in situ hybridization and immunohistochemistry.

The chick embryo is a valuable tool in the study of early embryonic development. Its transparency, accessibility and ease of manipulation, make it an ...

In utero and ex vivo Electroporation for Gene Expression in Mouse Retinal Ganglion Cells

The retina and its sole output neuron, the retinal ganglion cell (RGC), comprise an excellent model in which to examine biological questions such as cell differentiation, axon guidance, retinotopic organization and synapse formation[1]. One drawback is the inability to efficiently and reliably manipulate gene expression in RGCs in vivo, especially in the otherwise accessible murine visual pathways. Transgenic mice can be used to manipulate gene expression, but this approach is often expensive, time consuming, and can produce unwanted side effects. In chick, in ovo electroporation is used to manipulate gene expression in RGCs for examining retina and RGC development. Although similar electroporation techniques have been developed in neonatal mouse pups[2], adult rats[3], and embryonic murine retinae in vitro[4], none of these strategies allow full characterization of RGC development and axon projections in vivo. To this end, we have developed two applications of electroporation, one in utero and the other ex vivo, to specifically target embryonic murine RGCs[5, 6]. 
With in utero retinal electroporation, we can misexpress or downregulate specific genes in RGCs and follow their axon projections through the visual pathways in vivo, allowing examination of guidance decisions at intermediate targets, such as the optic chiasm, or at target regions, such as the lateral geniculate nucleus. Perturbing gene expression in a subset of RGCs in an otherwise wild-type background facilitates an understanding of gene function throughout the retinal pathway. Additionally, we have developed a companion technique for analyzing RGC axon growth in vitro. We electroporate embryonic heads ex vivo, collect and incubate the whole retina, then prepare explants from these retinae several days later. Retinal explants can be used in a variety of in vitro assays in order to examine the response of electroporated RGC axons to guidance cues or other factors. In sum, this set of techniques enhances our ability to misexpress or downregulate genes in RGCs and should greatly aid studies examining RGC development and axon projections.

In utero and ex vivo Electroporation for Gene Expression in Mouse Retinal Ganglion Cells

Here we present two techniques for manipulating gene expression in murine retinal ganglion cells (RGCs) by in utero and ex vivo electroporation. These techniques enable one to examine how alterations in gene expression affect RGC development, axon guidance, and functional properties.

The retina and its sole output neuron, the retinal ganglion cell (RGC), comprise an excellent model in which to examine biological questions such as cell ...

In-vivo Detection of Protein-protein Interactions on Micro-patterned Surfaces

Unraveling the interaction network of molecules in-vivo is key to understanding the mechanisms that regulate cell function and metabolism. A multitude of methodological options for addressing molecular interactions in cells have been developed, but most of these methods suffer from being rather indirect and therefore hardly quantitative. On the contrary, a few high-end quantitative approaches were introduced, which however are difficult to extend to high throughput. To combine high throughput capabilities with the possibility to extract quantitative information, we recently developed a new concept for identifying protein-protein interactions (Schwarzenbacher et al., 2008). Here, we describe a detailed protocol for the design and the construction of this system which allows for analyzing interactions between a fluorophore-labeled protein ("prey") and a membrane protein ("bait") in-vivo. Cells are plated on micropatterned surfaces functionalized with antibodies against the bait exoplasmic domain. Bait-prey interactions are assayed via the redistribution of the fluorescent prey. The method is characterized by high sensitivity down to the level of single molecules, the capability to detect weak interactions, and high throughput capability, making it applicable as screening tool.

In-vivo Detection of Protein-protein Interactions on Micro-patterned Surfaces

This video shows experiments with subsequent analysis of protein-protein interactions by the use of micro-patterned surfaces. The approach offers the possibility to detect protein interactions in living cells and combines high throughput capabilities with the possibility to extract quantitative information.

Unraveling the interaction network of molecules in-vivo is key to understanding the mechanisms that regulate cell function and metabolism. A multitude of ...

Using SecM Arrest Sequence as a Tool to Isolate Ribosome Bound Polypeptides

Extensive research has provided ample evidences suggesting that protein folding in the cell is a co-translational process1-5. However, the exact pathway that polypeptide chain follows during co-translational folding to achieve its functional form is still an enigma. In order to understand this process and to determine the exact conformation of the co-translational folding intermediates, it is essential to develop techniques that allow the isolation of RNCs carrying nascent chains of predetermined sizes to allow their further structural analysis.
SecM (secretion monitor) is a 170 amino acid E. coli protein that regulates expression of the downstream SecA (secretion driving) ATPase in the secM-secA operon6. Nakatogawa and Ito originally found that a 17 amino acid long sequence (150-FSTPVWISQAQGIRAGP-166) in the C-terminal region of the SecM protein is sufficient and necessary to cause stalling of SecM elongation at Gly165, thereby producing peptidyl-glycyl-tRNA stably bound to the ribosomal P-site7-9. More importantly, it was found that this 17 amino acid long sequence can be fused to the C-terminus of virtually any full-length and/or truncated protein thus allowing the production of RNCs carrying nascent chains of predetermined sizes7. Thus, when fused or inserted into the target protein, SecM stalling sequence produces arrest of the polypeptide chain elongation and generates stable RNCs both in vivo in E. coli cells and in vitro in a cell-free system. Sucrose gradient centrifugation is further utilized to isolate RNCs.
The isolated RNCs can be used to analyze structural and functional features of the co-translational folding intermediates. Recently, this technique has been successfully used to gain insights into the structure of several ribosome bound nascent chains10,11. Here we describe the isolation of bovine Gamma-B Crystallin RNCs fused to SecM and generated in an in vitro translation system.

We describe here a technique that is now routinely used to isolate stably bound ribosome nascent chain complexes (RNCs). This technique takes advantage of the discovery that a 17 amino acid long SecM "arrest sequence" can halt translation elongation in a prokaryotic (E. coli) system, when inserted into (or fused to the C-terminus) of virtually any protein.

Extensive research has provided ample evidences suggesting that protein folding in the cell is a co-translational process1-5. However, the exact pathway ...

Using Caenorhabditis elegans as a Model System to Study Protein Homeostasis in a Multicellular Organism

The folding and assembly of proteins is essential for protein function, the long-term health of the cell, and longevity of the organism. Historically, the function and regulation of protein folding was studied in vitro, in isolated tissue culture cells and in unicellular organisms. Recent studies have uncovered links between protein homeostasis (proteostasis), metabolism, development, aging, and temperature-sensing. These findings have led to the development of new tools for monitoring protein folding in the model metazoan organism Caenorhabditis elegans. In our laboratory, we combine behavioral assays, imaging and biochemical approaches using temperature-sensitive or naturally occurring metastable proteins as sensors of the folding environment to monitor protein misfolding. Behavioral assays that are associated with the misfolding of a specific protein provide a simple and powerful readout for protein folding, allowing for the fast screening of genes and conditions that modulate folding. Likewise, such misfolding can be associated with protein mislocalization in the cell. Monitoring protein localization can, therefore, highlight changes in cellular folding capacity occurring in different tissues, at various stages of development and in the face of changing conditions. Finally, using biochemical tools ex vivo, we can directly monitor protein stability and conformation. Thus, by combining behavioral assays, imaging and biochemical techniques, we are able to monitor protein misfolding at the resolution of the organism, the cell, and the protein, respectively.

Using Caenorhabditis elegans as a Model System to Study Protein Homeostasis in a Multicellular Organism

To study the relationship between protein homeostasis, stress and aging, we monitored changes in protein folding by following protein dysfunction, protein localization in the cell and protein stability at the organismal, cellular and protein levels, using the genetically tractable metazoan Caenorhabditis elegans as a model system.

The folding and assembly of proteins is essential for protein function, the long-term health of the cell, and longevity of the organism. Historically, the ...

Chromatin Immunoprecipitation Assay for the Identification of Arabidopsis Protein-DNA Interactions In Vivo

Intricate gene regulatory networks orchestrate biological processes and developmental transitions in plants. Selective transcriptional activation and silencing of genes mediate the response of plants to environmental signals and developmental cues. Therefore, insights into the mechanisms that control plant gene expression are essential to gain a deep understanding of how biological processes are regulated in plants. The chromatin immunoprecipitation (ChIP) technique described here is a procedure to identify the DNA-binding sites of proteins in genes or genomic regions of the model species Arabidopsis thaliana. The interactions with DNA of proteins of interest such as transcription factors, chromatin proteins or posttranslationally modified versions of histones can be efficiently analyzed with the ChIP protocol. This method is based on the fixation of protein-DNA interactions in vivo, random fragmentation of chromatin, immunoprecipitation of protein-DNA complexes with specific antibodies, and quantification of the DNA associated with the protein of interest by PCR techniques. The use of this methodology in Arabidopsis has contributed significantly to unveil transcriptional regulatory mechanisms that control a variety of plant biological processes. This approach allowed the identification of the binding sites of the Arabidopsis chromatin protein EBS to regulatory regions of the master gene of flowering FT. The impact of this protein in the accumulation of particular histone marks in the genomic region of FT was also revealed through ChIP analysis.

Chromatin Immunoprecipitation Assay for the Identification of Arabidopsis Protein-DNA Interactions In Vivo

Chromatin immunoprecipitation is a powerful technique for the identification of DNA binding sites of Arabidopsis proteins in vivo. This procedure includes chromatin cross-linking and fragmentation, immunoprecipitation with selective antibodies against the protein of interest, and qPCR analysis of bound DNA. We describe a simple ChIP assay optimized for Arabidopsis plants.

Intricate gene regulatory networks orchestrate biological processes and developmental transitions in plants. Selective transcriptional activation and ...

Measuring the Stiffness of Ex Vivo Mouse Aortas Using Atomic Force Microscopy

Arterial stiffening is a significant risk factor and biomarker for cardiovascular disease and a hallmark of aging. Atomic force microscopy (AFM) is a versatile analytical tool for characterizing viscoelastic mechanical properties for a variety of materials ranging from hard (plastic, glass, metal, etc.) surfaces to cells on any substrate. It has been widely used to measure the stiffness of cells, but less frequently used to measure the stiffness of aortas. In this paper, we will describe the procedures for using AFM in contact mode to measure the ex vivo elastic modulus of unloaded mouse arteries. We describe our procedure for isolation of mouse aortas, and then provide detailed information for the AFM analysis. This includes step-by-step instructions for alignment of the laser beam, calibration of the spring constant and deflection sensitivity of the AFM probe, and acquisition of force curves. We also provide a detailed protocol for data analysis of the force curves.

Measuring the Stiffness of Ex Vivo Mouse Aortas Using Atomic Force Microscopy

We present detailed protocols for isolation of aortas from mouse and measurement of their elastic modulus using atomic force microscopy.

Arterial stiffening is a significant risk factor and biomarker for cardiovascular disease and a hallmark of aging. Atomic force microscopy (AFM) is a ...

In Vivo Detection and Analysis of Rb Protein SUMOylation in Human Cells

The post-translational modifications of proteins are critical for the proper regulation of intracellular signal transduction. Among these modifications, small ubiquitin-related modifier (SUMO) is a ubiquitin-like protein that is covalently attached to the lysine residues of a variety of target proteins to regulate cellular processes, such as gene transcription, DNA repair, protein interaction and degradation, subcellular transport, and signal transduction. The most common approach to detecting protein SUMOylation is based on the expression and purification of recombinant tagged proteins in bacteria, allowing for an in vitro biochemical reaction which is simple and suitable for addressing mechanistic questions. However, due to the complexity of the process of SUMOylation in vivo, it is more challenging to detect and analyze protein SUMOylation in cells, especially when under endogenous conditions. A recent study by the authors of this paper revealed that endogenous retinoblastoma (Rb) protein, a tumor suppressor that is vital to the negative regulation of the cell cycle progression, is specifically SUMOylated at the early G1 phase. This paper describes a protocol for the detection and analysis of Rb SUMOylation under both endogenous and exogenous conditions in human cells. This protocol is appropriate for the phenotypical and functional investigation of the SUMO-modification of Rb, as well as many other SUMO-targeted proteins, in human cells.

In Vivo Detection and Analysis of Rb Protein SUMOylation in Human Cells

Small ubiquitin-related modifier (SUMO) family proteins are conjugated to the lysine residues of target proteins to regulate various cellular processes. This paper describes a protocol for the detection of retinoblastoma (Rb) protein SUMOylation under endogenous and exogenous conditions in human cells.

The post-translational modifications of proteins are critical for the proper regulation of intracellular signal transduction. Among these modifications, ...

A Simple and Efficient Method for In Vivo Cardiac-specific Gene Manipulation by Intramyocardial Injection in Mice

Gene manipulation specifically in the heart significantly potentiate the investigation of cardiac disease pathomechanisms and their therapeutic potential. In vivo cardiac-specific gene delivery is commonly achieved by either systemic or local delivery. Systemic injection via tail vein is easy and efficient in manipulating cardiac gene expression by using recombinant adeno-associated virus 9 (AAV9). However, this method requires a relatively high amount of vector for efficient transduction, and may result in nontarget organ gene transduction. Here, we describe a simple, efficient, and time-saving method of intramyocardial injection for in vivo cardiac-specific gene manipulation in mice. Under anesthesia (without ventilation), the pectoral major and minor muscles were bluntly dissected, and the mouse heart was quickly exposed by manual externalization through a small incision at the fourth intercostal space. Subsequently, adenovirus encoding luciferase (Luc) and vitamin D receptor (VDR), or short hairpin RNA (shRNA) targeting VDR, was injected with a Hamilton syringe into the myocardium. Subsequent in vivo imaging demonstrated that luciferase was successfully overexpressed specifically in the heart. Moreover, Western blot analysis confirmed the successful overexpression or silencing of VDR in the mouse heart. Once mastered, this technique can be used for gene manipulation, as well as injection of cells or other materials such as nanogels in the mouse heart.

A Simple and Efficient Method for In Vivo Cardiac-specific Gene Manipulation by Intramyocardial Injection in Mice

Here we present a protocol for cardiac-specific gene manipulation in mice. Under anesthesia, the mouse hearts were externalized through the fourth intercostal space. Subsequently, adenoviruses encoding specific genes were injected with a syringe into the myocardium, followed by protein expression measurement via in vivo imaging and Western blot analysis.

Gene manipulation specifically in the heart significantly potentiate the investigation of cardiac disease pathomechanisms and their therapeutic potential. ...