Dr Ren&#39;s work is supported by the American Heart Association (13SDG14800019; BR), the Ann&#39;s Hope Foundation (FP00011709; BR), the American Cancer Society (86-004-26; the MCW Cancer Center to BR), and the National Institute of Health (HL136423; BR); Jordan Palmer is supported by the 2018 MCW CTSI 500 Stars Internship Program; P. Moran is supported by an Institutional Research Training Grant from NHLBI (5T35 HL072483-34).

For animal experiments, all methods described here have been approved by the Institutional Animal Care and Use Committee of the Medical College of Wisconsin.
1. Prepare reagents
<ol>
	<li>Prepare lysis buffer to concentrations of 10 mM HEPES, pH 7.4, 150 mM KCl, 5 mM MgCl2, 0.5 mM DTT, 100 &#181;g/mL cycloheximide, protease inhibitors, and recombinant RNase inhibitors to concentrations as described below.
	<ol>
		<li>Add following reagents to 500 mL of RNase-free deionized water: 1.19 g of HEPES, 5.59 g of KCl, 0.24 g of MgCl2, 35 mg of DTT, 0.5 mL of cycloheximide, and NaOH as needed until pH 7.4, EDTA-free protease inhibitors (one mini tablet per 10 mL) and RNase inhibitor (10 &#181;L/mL).</li>
		<li>Store in a 4 &#176;C fridge for up to 1 month.</li>
	</ol>
	</li>
	<li>Prepare a high-salt polysome wash buffer to concentrations of 10 mM HEPES, pH 7.4, 350 mM KCl, 5 mM MgCl2, 1% vol/vol CA-630, 0.5 mM DTT, and 100 &#181;g/mL cycloheximide.
	<ol>
		<li>Add following reagents to 500 mL of RNase-free deionized water: 1.19 g of HEPES, 13.05 g of KCl, 0.24 g of MgCl2, 5 mL of nonionic, non-denaturing detergent, 5 of 7.7 mg tubes of DTT, and 0.5 mL of cycloheximide, and NaOH as needed until pH 7.4.</li>
		<li>Store in 4 &#176;C fridge for up to 1 month.</li>
	</ol>
	</li>
	<li>Bind anti-GFP antibody to Protein G magnetic beads prior to starting experiment.
	<ol>
		<li>Add 10 &#181;g of anti-GFP antibody diluted in 200 &#181;L of PBS to Protein G beads.</li>
		<li>Incubate with end over end rotation for 10 minutes at room temperature.</li>
		<li>Place the beads on a magnetic rack and remove the supernatant.</li>
		<li>Suspend the beads in 200 &#181;L of PBS and store in 4 &#176;C fridge for up to 1 week.</li>
	</ol>
	</li>
	<li>Prepare ice-cold PBS with 100 &#181;g/mL cycloheximide.
	<ol>
		<li>Add 1 volume of cycloheximide solution (100 mg/mL) to 999 volumes of ice-cold PBS.</li>
	</ol>
	</li>
</ol>
2. Isolate and lyse desired tissues
<ol>
	<li>Euthanize mice by IP injection of ketamine (500 mg/kg/body weight) and xylazine (10 mg/kg/body weight) and isolate desired tissues (i.e., heart, lung). Immediately proceed to next step.</li>
	<li>Place desired tissues into 500 &#181;L of ice-cold PBS with 100 &#181;g/mL cycloheximide.</li>
	<li>Mince tissue into a cell suspension with a motor-driven homogenizer or a small-clearance glass homogenizer. If using a motor-driven homogenizer, limit homogenization to less than 1 minute at low frequency (&#60;15,000 Hz) to avoid RNA denaturation.</li>
	<li>Suspend cell pellet in 200 &#181;L of lysis buffer by pipetting and redrawing up buffer several times. Further homogenize cell suspension with 10 strokes in a small-clearance glass homogenizer or for 15 seconds at low frequency (&#60;15,000 Hz) in a motor driven homogenizer.</li>
	<li>Centrifuge homogenates for 10 min at 2,000 x g at 4 &#176;C to pellet nuclei and large cell debris, and keep the supernatant.</li>
	<li>Add nonionic, non-denaturing detergent to 1% vol/vol and DHPC to 30 mM to the supernatant. Incubate on ice for 5 min.</li>
	<li>Centrifuge lysate for 10 min at 16,000 x g to pellet insoluble material. Transfer and keep 15% of clear lysate as input for future steps.</li>
</ol>
3. Isolate ribosome/mRNA complexes
<ol>
	<li>Add 50 &#181;L of antibody-bound beads to cell-lysate supernatant and incubate mixture at 4 &#176;C with end-over-end rotation for 30 min. This is where the anti-GFP antibodies will bind the GFP-tagged ribosomes, allowing us to further isolate the RNA from these ribosomes.</li>
	<li>Collect beads on a magnetic rack and wash 5 times with high-salt polysome wash buffer.
	<ol>
		<li>Draw up and discard liquid once beads have collected on the side of the tube. Then pipette and redraw up 200 &#181;L of high-salt polysome wash buffer several times. Repeat this step 5 times and discard all buffer following final repetition. Immediately proceed to next step.</li>
	</ol>
	</li>
</ol>
4. Isolate mRNA
<ol>
	<li>Place beads in RLT buffer. The following steps are taken directly from the RNeasy mini kit protocol and were not expanded on in any way. 
	CAUTION: RLT buffer contains guanidine salts; do NOT mix with bleach.</li>
	<li>Centrifuge lysate for 3 min at full speed 13,000 rpm or 16,000 g at 4 &#176;C. Carefully remove supernatant of 350 &#181;L by pipetting and transfer it to a new microfuge tube. Use only this supernatant (lysate) in subsequent steps.</li>
	<li>Add an equal volume of 70% ethanol into the microfuge tube.</li>
	<li>Transfer up to 700 &#181;L of the sample, including any precipitate that may have formed, to a spin column placed in a 2 mL collection tube. Close the lid gently and centrifuge for 15 s at &#8805;8,000 x g to wash the spin column membrane. Discard the flow-through.</li>
	<li>Add 350 &#181;L of buffer RW1 to the spin column. Close the lid gently and centrifuge for 15 s at &#8805;8,000 x g to wash the spin column membrane. Discard the flow-through and reuse the collection tube in next step. 
	CAUTION: Buffer RW1 contains guanidine salts; do NOT mix with bleach.</li>
	<li>Add 350 &#181;L of buffer RW1 to the spin column. Close the lid gently and centrifuge for 15 s at &#8805;8,000 x g. Discard the flow-through.</li>
	<li>Add 500 &#181;L of buffer RPE to the spin column. Close the lid gently and centrifuge for 15 s at &#8805;8,000 x g to wash the spin column membrane. Discard the flow-through.</li>
	<li>Add 500 &#181;L of buffer RPE to the spin column. Close the lid gently and centrifuge for 2 min at &#8805;8,000 x g to wash the spin column membrane. Then carefully remove the spin column from the collection tube, ensuring that the column does not contact the flow-through.</li>
	<li>Place the spin column in a new 2 mL collection tube and discard the old tube with the flow-through. Close the lid gently and centrifuge at full speed for 1 min to remove residual buffer.</li>
	<li>Place the spin column in a new 1.5 mL collection tube. Add 30-50 &#181;L of RNase-free water directly to the spin column membrane. Close the lid gently and centrifuge for 1 min at &#8805;8,000 x g to elute the RNA.</li>
	<li>If expected RNA yield is &#62;30 &#181;g, repeat step 4.10 with another 30-50 &#181;L of RNase-free water, or using elute from Step 4.10 (if high [RNA] is required). Reuse collection tube from Step 4.10.</li>
	<li>Use purified RNA for downstream analysis including RNA-sequencing or real time quantitative PCR or store RNA dissolved in RNase-free H2O at -80 &#176;C for up to 1 year.</li>
</ol>

<ol>
	<li>Heiman, M., Kulicke, R., Fenster, R. J., Greengard, P., Heintz, N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cell+type-specific+mRNA+purification+by+translating+ribosome+affinity+purification+(TRAP).">Cell type-specific mRNA purification by translating ribosome affinity purification (TRAP).</a> Nature Protocols. 9, 1282-1291 (2014).</li><li>Zhou, P., 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=Interrogating+translational+efficiency+and+lineage-specific+transcriptomes+using+ribosome+affinity+purification.">Interrogating translational efficiency and lineage-specific transcriptomes using ribosome affinity purification.</a> Proceedings of the National Academy of Sciences of the United States of America. 110, 15395-15400 (2013).</li><li>Best, B., Moran, P., Ren, B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=VEGF/PKD-1+signaling+mediates+arteriogenic+gene+expression+and+angiogenic+responses+in+reversible+human+microvascular+endothelial+cells+with+extended+lifespan.">VEGF/PKD-1 signaling mediates arteriogenic gene expression and angiogenic responses in reversible human microvascular endothelial cells with extended lifespan.</a> Molecular and Cellular Biochemistry. 446, 199-207 (2018).</li><li>Ren, B., 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=LPA/PKD-1-FoxO1+Signaling+Axis+Mediates+Endothelial+Cell+CD36+Transcriptional+Repression+and+Proangiogenic+and+Proarteriogenic+Reprogramming.">LPA/PKD-1-FoxO1 Signaling Axis Mediates Endothelial Cell CD36 Transcriptional Repression and Proangiogenic and Proarteriogenic Reprogramming.</a> Arteriosclerosclerosis Thrombosis, Vascular Biology. 36, 1197-1208 (2016).</li><li>Ren, B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Protein+Kinase+D1+Signaling+in+Angiogenic+Gene+Expression+and+VEGF-Mediated+Angiogenesis.">Protein Kinase D1 Signaling in Angiogenic Gene Expression and VEGF-Mediated Angiogenesis.</a> Frontiers in Cell and Developmental Biology. 4, 37 (2016).</li><li>Ren, B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=FoxO1+transcriptional+activities+in+VEGF+expression+and+beyond:+a+key+regulator+in+functional+angiogenesis?.">FoxO1 transcriptional activities in VEGF expression and beyond: a key regulator in functional angiogenesis?.</a> Journal of Pathology. 245, 255-257 (2018).</li><li>Hupe, M., Li, M. X., Gertow Gillner, K., Adams, R. H., Stenman, J. M. <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+TRAP-sequencing+technology+with+a+versatile+conditional+mouse+model.">Evaluation of TRAP-sequencing technology with a versatile conditional mouse model.</a> Nucleic Acids Research. 42, e14 (2014).</li><li>Dong, L., 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=Diet-induced+obesity+links+to+ER+positive+breast+cancer+progression+via+LPA/PKD-1-CD36+signaling-mediated+microvascular+remodeling.">Diet-induced obesity links to ER positive breast cancer progression via LPA/PKD-1-CD36 signaling-mediated microvascular remodeling.</a> Oncotarget. 8, 22550-22562 (2017).</li><li>Ren, B., 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=ERK1/2-Akt1+crosstalk+regulates+arteriogenesis+in+mice+and+zebrafish.">ERK1/2-Akt1 crosstalk regulates arteriogenesis in mice and zebrafish.</a> Journal of Clinical Investigation. 120, 1217-1228 (2010).</li><li>Skuli, N., 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=Endothelial+HIF-2alpha+regulates+murine+pathological+angiogenesis+and+revascularization+processes.">Endothelial HIF-2alpha regulates murine pathological angiogenesis and revascularization processes.</a> Journal of Clinical Investigation. 122, 1427-1443 (2012).</li></ol>

The authors declare that they have no conflict of interest.

Angiogenesis is a complex multistep process, in which EC-specific angiogenic gene transcription and expression play an essential role in EC differentiation and angiogenic reprogramming3,4. To overcome the barriers from the cellular diversity and architectural complexity for better understanding the function of the mammalian vascular system at a molecular level in vivo, we have created EC-specific TRAP mice, accompanied by EC-specific cd36, EC-specific <e...

In complex tissues such as the mammalian brain, heart and lung, the high levels of cellular heterogeneity complicate the analysis of gene expression data derived from whole tissue samples. To observe gene expression profiles in a particular cell type in vivo, a new methodology has been developed recently, which allows the interrogation of the entire translated mRNA complement of any genetically defined cell type. This methodology is known as the translating ribosome affinity purification (TRAP) technique1,2. It is a useful tool to study endothelial cell biology and angiogenesis when combined with genetically manipulating other angiogenesis-associated genes in animals.
We have shown that angiogenic PKD-1 signaling and the transcription of angiogenic gene CD36 are critical for endothelial cell (EC) differentiation and functional angiogenesis3,4,5,6. To determine molecular mechanisms of angiogenic and metabolic signaling in gene transcription and EC transdifferentiation, we have created genetically engineered TRAP mice with specifically deleted angiogenic genes on the basis of TRAP technique1,2. Furthermore, in our TRAP animals, not only do they have pkd-1 or cd36 gene deficiency in the vascular endothelia or global deletion of cd36 gene, but an enhanced green fluorescence protein (EGFP) is also genetically tagged onto EC&#39;s translating ribosomes. TRAP permits affinity purification of ribosome-bound mRNA directly from the vascular endothelia of targeted tissues, enabling the analysis of gene expression and identification of new transcriptomes that are associated with EC differentiation and angiogenesis directly under in vivo conditions. We have successfully isolated ribosome-bound RNA from the endothelia in these genetically engineered animals. The purified RNA can be used for further characterization of angiogenic or arteriogenic genes in the regulation of EC differentiation and functions. This protocol provides a step-by-step guide to implement the TRAP approach for the isolation of mRNA in ECs directly in vivo.

<table border="0" cellpadding="0" cellspacing="0" style="width:591px;" width="589">
	<tbody>
		<tr height="42">
			<td height="42" style="height:42px;width:223px;">2100 Electrophoresis Bioanalyzer with Nanochips and Picochips</td>
			<td style="width:73px;">Agilent</td>
			<td style="width:123px;">G2939AA, 5067-1511 &#38; 5067-1513</td>
			<td style="width:172px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:223px;">Cell scrapers</td>
			<td style="width:73px;">Sarstedt</td>
			<td align="right" style="width:123px;">83.1832</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:223px;">Homogenizers</td>
			<td style="width:73px;">Fisher Scientific</td>
			<td style="width:123px;">K8855100020</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:223px;">Magnet (Dynamag-2)</td>
			<td style="width:73px;">Invitrogen</td>
			<td style="width:123px;">123-21D</td>
			<td>Will depend on purification scale; samples in 1.5-mL tubes can be concentrated on a DynaMag-2</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:223px;">Minicentrifuge</td>
			<td style="width:73px;">Fisher Scientific</td>
			<td style="width:123px;">05-090-100</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:223px;">NanoDrop 2000C spectrophotometer</td>
			<td style="width:73px;">Thermo Scientific&#160;</td>
			<td style="width:123px;">ND-2000C</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:223px;">Refrigerated centrifuge</td>
			<td style="width:73px;">Eppendorf</td>
			<td style="width:123px;">5430R</td>
			<td>with rotor for 1.5-mL microcentrifuge tubes</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:223px;">RNase-free 1.5mL microcentrifuge tubes</td>
			<td style="width:73px;">Applied Biosystems&#160;</td>
			<td style="width:123px;">AM12450</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:223px;">Rnase-free 50-mL conical tubes</td>
			<td style="width:73px;">Applied Biosystems&#160;</td>
			<td style="width:123px;">AM12501</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:223px;">RNase-free 1000-&#956;l filter tips</td>
			<td style="width:73px;">Rainin</td>
			<td style="width:123px;">RT-1000F</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:223px;">RNase-free 200-&#956;l filter tips</td>
			<td style="width:73px;">Rainin&#160;</td>
			<td style="width:123px;">RT-200F</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:223px;">RNase-free 20-&#956;l filter tips</td>
			<td style="width:73px;">Rainin&#160;</td>
			<td style="width:123px;">RT-20F</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:223px;">Rotor for homogenizers</td>
			<td style="width:73px;">Yamato&#160;</td>
			<td style="width:123px;">LT-400D</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:223px;">Tube rotator, Labquake brand</td>
			<td style="width:73px;">Thermo Fisher</td>
			<td style="width:123px;">13-687-12Q</td>
			<td></td>
		</tr>
	</tbody>
</table>

translating ribosome affinity purification (trap) for rna isolation from endothelial cells in vivo

Many studies have been limited to using in vitro cellular assays and whole tissues or isolating of specific cell types from animals for in vitro analysis of transcriptome and gene expression by qPCR and RNA sequencing. Comprehensive transcriptome and gene expression analysis of specific cell types in complex tissues and organs will be critical to understand cellular and molecular mechanisms by which genes are regulated and their association with tissue homeostasis and organ functions. In this article, we demonstrate the methodology for isolation of ribosome-bound RNA directly in vivo in the vascular endothelia of animal lungs as an example. The specific materials and procedures for tissue processing and RNA purification will be described, including the assessment of RNA quality and yield as well as real time qPCR for arteriogenic gene assays. This approach, known as translating ribosome affinity purification (TRAP) technique, can be utilized for characterization of gene expression and transcriptome analysis of certain cell types directly in vivo in any specific type in complex tissues.

Our previous studies4,7 suggest that CD36 may function as a switch for arteriolar differentiation and capillary arterialization via the LPA/PKD-1 signaling pathway. To study whether the LPA/PKD-1-CD36 signaling axis is essential for arteriogenesis in vivo, we have established the novel TRAP lines that not only have global cd36 deficiency or endothelial-specific-cd36- or pkd-1-deficiency but also permit selective isolation of ribosome-bound RNA from cre-marked cel...

Watch this Scientific Journal Video about Translating Ribosome Affinity Purification TRAP for RNA Isolation from Endothelial Cells In Vivo at JoVE.com

Translating Ribosome Affinity Purification TRAP for RNA Isolation from Endothelial Cells In Vivo

We present an approach to purify ribosome-bound mRNA from vascular endothelial cells (ECs) directly in mouse brain, lung and heart tissues via EC-specific genetic tag of enhanced green fluorescence protein (EGFP)in ribosomes in combination with RNA purification.

Translating Ribosome Affinity Purification (TRAP) for RNA Isolation from Endothelial Cells In Vivo

Many studies have been limited to using in vitro cellular assays and whole tissues or isolating of specific cell types from animals for in vitro analysis ...

translating-ribosome-affinity-purification-trap-for-rna-isolation

Research

JoVE Journal

Biochemistry

11.7K Views.  Blood Center of Wisconsin. We present an approach to purify ribosome-bound mRNA from vascular endothelial cells (ECs) directly in mouse brain, lung and heart tissues via EC-specific genetic tag of enhanced green fluorescence protein (EGFP)in ribosomes in combination with RNA purification.

Video: Translating Ribosome Affinity Purification TRAP for RNA Isolation from Endothelial Cells In Vivo

Isolation of Cognate RNA-protein Complexes from Cells Using Oligonucleotide-directed Elution

Ribonucleoprotein particles direct the biogenesis and post-transcriptional regulation of all mRNAs through distinct combinations of RNA binding proteins. They are composed of position-dependent, cis-acting RNA elements and unique combinations of RNA binding proteins. Defining the composition of a specific RNP is essential to achieving a fundamental understanding of gene regulation. The isolation of a select RNP is akin to finding a needle in a haystack. Here, we demonstrate an approach to isolate RNPs associated at the 5' untranslated region of a select mRNA in asynchronous, transfected cells. This cognate RNP has been demonstrated to be necessary for the translation of select viruses and cellular stress-response genes.
The demonstrated RNA-protein co-precipitation protocol is suitable for the downstream analysis of protein components through proteomic analyses, immunoblots, or suitable biochemical identification assays. This experimental protocol demonstrates that DHX9/RNA helicase A is enriched at the 5' terminus of cognate retroviral RNA and provides preliminary information for the identification of its association with cell stress-associated huR and junD cognate mRNAs.

This manuscript describes an approach to isolate select cognate RNPs formed in eukaryotic cells via a specific oligonucleotide-directed enrichment. We demonstrate the applicability of this approach by isolating a cognate RNP bound to the retroviral 5' untranslated region that is composed of DHX9/RNA helicase A.

Ribonucleoprotein particles direct the biogenesis and post-transcriptional regulation of all mRNAs through distinct combinations of RNA binding proteins. ...

Protein Complex Affinity Capture from Cryomilled Mammalian Cells

Affinity capture is an effective technique for isolating endogenous protein complexes for further study. When used in conjunction with an antibody, this technique is also frequently referred to as immunoprecipitation. Affinity capture can be applied in a bench-scale and in a high-throughput context. When coupled with protein mass spectrometry, affinity capture has proven to be a workhorse of interactome analysis. Although there are potentially many ways to execute the numerous steps involved, the following protocols implement our favored methods. Two features are distinctive: the use of cryomilled cell powder to produce cell extracts, and antibody-coupled paramagnetic beads as the affinity medium. In many cases, we have obtained superior results to those obtained with more conventional affinity capture practices. Cryomilling avoids numerous problems associated with other forms of cell breakage. It provides efficient breakage of the material, while avoiding denaturation issues associated with heating or foaming. It retains the native protein concentration up to the point of extraction, mitigating macromolecular dissociation. It reduces the time extracted proteins spend in solution, limiting deleterious enzymatic activities, and it may reduce the non-specific adsorption of proteins by the affinity medium. Micron-scale magnetic affinity media have become more commonplace over the last several years, increasingly replacing the traditional agarose- and Sepharose-based media. Primary benefits of magnetic media include typically lower non-specific protein adsorption; no size exclusion limit because protein complex binding occurs on the bead surface rather than within pores; and ease of manipulation and handling using magnets.

Here we describe protocols to disrupt mammalian cells by solid-state milling at a cryogenic temperature, produce a cell extract from the resulting cell powder, and isolate protein complexes of interest by affinity capture upon antibody-coupled micron-scale paramagnetic beads.

Affinity capture is an effective technique for isolating endogenous protein complexes for further study. When used in conjunction with an antibody, this ...

An Efficient Method for the Isolation of Highly Purified RNA from Seeds for Use in Quantitative Transcriptome Analysis

Plant seeds accumulate large amounts of storage reserves comprising biodegradable organic matter. Humans rely on seed storage reserves for food and as industrial materials. Gene expression profiles are powerful tools for investigating metabolic regulation in plant cells. Therefore, detailed, accurate gene expression profiles during seed development are required for crop breeding. Acquiring highly purified RNA is essential for producing these profiles. Efficient methods are needed to isolate highly purified RNA from seeds. Here, we describe a method for isolating RNA from seeds containing large amounts of oils, proteins, and polyphenols, which have inhibitory effects on high-purity RNA isolation. Our method enables highly purified RNA to be obtained from seeds without the use of phenol, chloroform, or additional processes for RNA purification. This method is applicable to Arabidopsis, rapeseed, and soybean seeds. Our method will be useful for monitoring the expression patterns of low level transcripts in developing and mature seeds.

We have succeeded in establishing a method for RNA isolation from plant seeds containing large amounts of oils, proteins, and polyphenols, which have inhibitory effects on high-purity RNA isolation. Our method is suitable for monitoring the expression of genes with low level transcripts in seeds.

Plant seeds accumulate large amounts of storage reserves comprising biodegradable organic matter. Humans rely on seed storage reserves for food and as ...

Tandem Affinity Purification of Protein Complexes from Eukaryotic Cells

The purification of active protein-protein and protein-nucleic acid complexes is crucial for the characterization of enzymatic activities and de novo identification of novel subunits and post-translational modifications. Bacterial systems allow for the expression and purification of a wide variety of single polypeptides and protein complexes. However, this system does not enable the purification of protein subunits that contain post-translational modifications (e.g., phosphorylation and acetylation), and the identification of novel regulatory subunits that are only present/expressed in the eukaryotic system. Here, we provide a detailed description of a novel, robust, and efficient tandem affinity purification (TAP) method using STREP- and FLAG-tagged proteins that facilitates the purification of protein complexes with transiently or stably expressed epitope-tagged proteins from eukaryotic cells. This protocol can be applied to characterize protein complex functionality, to discover post-translational modifications on complex subunits, and to identify novel regulatory complex components by mass spectrometry. Notably, this TAP method can be applied to study protein complexes formed by eukaryotic or pathogenic (viral and bacterial) components, thus yielding a wide array of downstream experimental opportunities. We propose that researchers working with protein complexes could utilize this approach in many different ways.

We describe here a novel, robust, and efficient tandem affinity purification (TAP) method for the expression, isolation, and characterization of protein complexes from eukaryotic cells. This protocol could be utilized for the biochemical characterization of discrete complexes as well as the identification of novel interactors and post-translational modifications that regulate their function.

The purification of active protein-protein and protein-nucleic acid complexes is crucial for the characterization of enzymatic activities and de novo ...

Identification of Plant Ice-binding Proteins Through Assessment of Ice-recrystallization Inhibition and Isolation Using Ice-affinity Purification

Ice-binding proteins (IBPs) belong to a family of stress-induced proteins that are synthesized by certain organisms exposed to subzero temperatures. In plants, freeze damage occurs when extracellular ice crystals grow, resulting in the rupture of plasma membranes and possible cell death. Adsorption of IBPs to ice crystals restricts further growth by a process known as ice-recrystallization inhibition (IRI), thereby reducing cellular damage. IBPs also demonstrate the ability to depress the freezing point of a solution below the equilibrium melting point, a property known as thermal hysteresis (TH) activity. These protective properties have raised interest in the identification of novel IBPs due to their potential use in industrial, medical and agricultural applications. This paper describes the identification of plant IBPs through 1) the induction and extraction of IBPs in plant tissue, 2) the screening of extracts for IRI activity, and 3) the isolation and purification of IBPs. Following the induction of IBPs by low temperature exposure, extracts are tested for IRI activity using a &#39;splat assay&#39;, which allows the observation of ice crystal growth using a standard light microscope. This assay requires a low protein concentration and generates results that are quickly obtained and easily interpreted, providing an initial screen for ice binding activity. IBPs can then be isolated from contaminating proteins by utilizing the property of IBPs to adsorb to ice, through a technique called &#39;ice-affinity purification&#39;. Using cell lysates collected from plant extracts, an ice hemisphere can be slowly grown on a brass probe. This incorporates IBPs into the crystalline structure of the polycrystalline ice. Requiring no a priori biochemical or structural knowledge of the IBP, this method allows for recovery of active protein. Ice-purified protein fractions can be used for downstream applications including the identification of peptide sequences by mass spectrometry and the biochemical analysis of native proteins.

This paper outlines the identification of ice-binding proteins from freeze-tolerant plants through the assessment of ice-recrystallization inhibition activity and subsequent isolation of native IBPs using ice-affinity purification.

Ice-binding proteins (IBPs) belong to a family of stress-induced proteins that are synthesized by certain organisms exposed to subzero temperatures. In ...

A G-quadruplex DNA-affinity Approach for Purification of Enzymatically Active G4 Resolvase1

Higher-order nucleic acid structures called G-quadruplexes (G4s, G4 structures) can form in guanine-rich regions of both DNA and RNA and are highly thermally stable. There are &#62;375,000 putative G4-forming sequences in the human genome, and they are enriched in promoter regions, untranslated regions (UTRs), and within the telomeric repeat. Due to the potential for these structures to affect cellular processes, such as replication and transcription, the cell has evolved enzymes to manage them. One such enzyme is G4 Resolvase 1 (G4R1), which was biochemically co-characterized by our laboratory and Nagamine et al. and found to bind extremely tightly to both G4-DNA and G4-RNA (Kd in the low-pM range). G4R1 is the source of the majority of G4-resolving activity in HeLa cell lysates and has since been implicated to play a role in telomere metabolism, lymph development, gene transcription, hematopoiesis, and immune surveillance. The ability to efficiently express and purify catalytically active G4R1 is of importance for laboratories interested in gaining further insight into the kinetic interaction of G4 structures and G4-resolving enzymes. Here, we describe a detailed method for the purification of recombinant G4R1 (rG4R1). The described procedure incorporates the traditional affinity-based purification of a C-terminal histidine-tagged enzyme expressed in human codon-optimized bacteria with the utilization of the ability of rG4R1 to bind and unwind G4-DNA to purify highly active enzyme in an ATP-dependent elution step. The protocol also includes a quality-control step where the enzymatic activity of rG4R1 is measured by examining the ability of the purified enzyme to unwind G4-DNA. A method is also described that allows for the quantification of purified rG4R1. Alternative adaptations of this protocol are discussed.

G4 Resolvase1 binds to G-quadruplex (G4) structures with the tightest reported affinity for a G4-binding protein and represents the majority of the G4-DNA unwinding activity in HeLa cells. We describe a novel protocol that harnesses the affinity and ATP-dependent unwinding activity of G4-Resolvase1 to specifically purify catalytically active recombinant G4R1.

Higher-order nucleic acid structures called G-quadruplexes (G4s, G4 structures) can form in guanine-rich regions of both DNA and RNA and are highly ...

Purification of Biotinylated Cell Surface Proteins from Rhipicephalus microplus Epithelial Gut Cells

Rhipicephalus microplus &#8211; the cattle tick &#8211; is the most significant ectoparasite in terms of economic impact on livestock as a vector of several pathogens. Efforts have been dedicated to the cattle tick control to diminish its deleterious effects, with focus on the discovery of vaccine candidates, such as BM86, located on the surface of the tick gut epithelial cells. Current research focuses upon the utilization of cDNA and genomic libraries, to screen for other vaccine candidates. The isolation of tick gut cells constitutes an important advantage in investigating the composition of surface proteins upon the tick gut cells membrane. This paper constitutes a novel and feasible method for the isolation of epithelial cells, from the tick gut contents of semi-engorged R. microplus. This protocol utilizes TCEP and EDTA to release the epithelial cells from the subepithelial support tissues and a discontinuous density centrifugation gradient to separate epithelial cells from other cell types. Cell surface proteins were biotinylated and isolated from the tick gut epithelial cells, using streptavidin-linked magnetic beads allowing for downstream applications in FACS or LC-MS/MS-analysis.

Purification of Biotinylated Cell Surface Proteins from Rhipicephalus microplus Epithelial Gut Cells

A modified density centrifugation gradient-based methodology was utilized to isolate epithelial cells from Rhipicephalus microplus gut tissue. Surface-bound proteins were biotinylated and purified through streptavidin magnetic beads for utilization in downstream applications.

Rhipicephalus microplus &#8211; the cattle tick &#8211; is the most significant ectoparasite in terms of economic impact on livestock as a vector of ...

Purification of Hepatocytes and Sinusoidal Endothelial Cells from Mouse Liver Perfusion

This protocol demonstrates a method for obtaining high yield and viability for mouse hepatocytes and sinusoidal endothelial cells (SECs) suitable for culturing or for obtaining cell lysates. In this protocol, the portal vein is used as the site for catheterization, rather than the vena cava, as this limits contamination of other possible cell types in the final liver preparation. No special instrumentation is required throughout the procedure. A water bath is used as a source of heat to maintain the temperature of all the buffers and solutions. A standard peristaltic pump is used to drive the fluid, and a refrigerated table-top centrifuge is required for the centrifugation procedures. The only limitation of this technique is the placement of the catheter within the portal vein, which is challenging on some of the mice in the 18 - 25 g size range. An advantage of this technique is that only one vein is utilized for the perfusion and the access to the vein is quick, which minimizes ischemia and reperfusion of the liver that reduces hepatic cell viability. Another advantage to this protocol is that it is easy to distinguish live from dead hepatocytes by eyesight due to the difference in cellular density during the centrifugation steps. Cells from this protocol may be used in cell culture for any downstream application as well as processed for any biochemical assessment.

The goal of this protocol is to obtain high viability and high yield of hepatocytes and sinusoidal endothelial cells from liver. This is accomplished by perfusing the liver with a type IV collagenase solution via the portal vein, followed by differential centrifugation to obtain hepatocytes and sinusoidal endothelial cells.

This protocol demonstrates a method for obtaining high yield and viability for mouse hepatocytes and sinusoidal endothelial cells (SECs) suitable for ...

Rapid Isolation of the Mitoribosome from HEK Cells

The human mitochondria possess a dedicated set of ribosomes (mitoribosomes) that translate 13 essential protein components of the oxidative phosphorylation complexes encoded by the mitochondrial genome. Since all proteins synthesized by human mitoribosomes are integral membrane proteins, human mitoribosomes are tethered to the mitochondrial inner membrane during translation. Compared to the cytosolic ribosome the mitoribosome has a sedimentation coefficient of 55S, half the rRNA content, no 5S rRNA and 36 additional proteins. Therefore, a higher protein-to-RNA ratio and an atypical structure make the human mitoribosome substantially distinct from its cytosolic counterpart.
Despite the central importance of the mitoribosome to life, no protocols were available to purify the intact complex from human cell lines. Traditionally, mitoribosomes were isolated from mitochondria-rich animal tissues that required kilograms of starting material. We reasoned that mitochondria in dividing HEK293-derived human cells grown in nutrient-rich expression medium would have an active mitochondrial translation, and, therefore, could be a suitable source of material for the structural and biochemical studies of the mitoribosome. To investigate its structure, we developed a protocol for large-scale purification of intact mitoribosomes from HEK cells. Herein, we introduce nitrogen cavitation method as a faster, less labor-intensive and more efficient alternative to traditional mechanical shear-based methods for cell lysis. This resulted in preparations of the mitoribosome that allowed for its structural determination to high resolution, revealing the composition of the intact human mitoribosome and its assembly intermediates. Here, we follow up on this work and present an optimized and more cost-effective method requiring only ~1010 cultured HEK cells. The method can be employed to purify human mitoribosomal translating complexes, mutants, quality control assemblies and mitoribosomal subunits intermediates. The purification can be linearly scaled up tenfold if needed, and also applied to other types of cells.

Mitochondria have specialized ribosomes that diverged from their bacterial and cytoplasmic counterparts. Here we show how mitoribosomes can be obtained from their native compartment in HEK cells. The method involves isolation of mitochondria from suspension cells and consequent purification of mitoribosomes.

The human mitochondria possess a dedicated set of ribosomes (mitoribosomes) that translate 13 essential protein components of the oxidative ...

MS2-Affinity Purification Coupled with RNA Sequencing in Gram-Positive Bacteria

Although small regulatory RNAs (sRNAs) are widespread among the bacterial domain of life, the functions of many of them remain poorly characterized notably due to the difficulty of identifying their mRNA targets. Here, we described a modified protocol of the MS2-Affinity Purification coupled with RNA Sequencing (MAPS) technology, aiming to reveal all RNA partners of a specific sRNA in vivo. Broadly, the MS2 aptamer is fused to the 5&#8217; extremity of the sRNA of interest. This construct is then expressed in vivo, allowing the MS2-sRNA to interact with its cellular partners. After bacterial harvesting, cells are mechanically lysed. The crude extract is loaded into an amylose-based chromatography column previously coated with the MS2 protein fused to the maltose binding protein. This enables the specific capture of MS2-sRNA and interacting RNAs. After elution, co-purified RNAs are identified by high-throughput RNA sequencing and subsequent bioinformatic analysis. The following protocol has been implemented in the Gram-positive human pathogen Staphylococcus aureus and is, in principle, transposable to any Gram-positive bacteria. To sum up, MAPS technology constitutes an efficient method to deeply explore the regulatory network of a particular sRNA, offering a snapshot of its whole targetome. However, it is important to keep in mind that putative targets identified by MAPS still need to be validated by complementary experimental approaches.

MAPS technology has been developed to scrutinize the targetome of a specific regulatory RNA in vivo. The sRNA of interest is tagged with a MS2 aptamer enabling the co-purification of its RNA partners and their identification by RNA sequencing. This modified protocol is particularly suited for Gram-positive bacteria.&#160;

Although small regulatory RNAs (sRNAs) are widespread among the bacterial domain of life, the functions of many of them remain poorly characterized ...