NIH P01 HL112730 (RAG, JVE), NIH R01 HL132075 (RAG, JVE), Barbra Streisand Women&#39;s Heart Center (RAG, JVE), Dorothy and E. Phillip Lyon Chair in Molecular Cardiology (RAG), Erika Glazer Endowed Chair in Woman&#39;s Heart Health (JVE) and Czech Academy of Sciences Institutional Support RVO: 68081715 (MS).

All animal studies were performed in accordance with institutional guidelines and approved by the Institutional Animal Care and Use Committee of Cedars-Sinai Medical Center.
1. Langendorff Perfusion of Mouse Heart
<ol>
	<li>Langendorff perfusion of mouse heart with ischemia and reperfusion 
	<ol>
		<li>Administer intraperitoneal pentobarbital sodium 70 mg/kg to the adult mouse (8-week-old, male, C57BL6/j). Confirm deep anesthesia by lack of withdrawal to toe pinch.</li>
		<l...

<ol>
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Laboratory methods in enzymology: Rna. Preface.</a> Methods in Enzymology. 530, xxi (2013).</li><li>Kuzniewska, B., Chojnacka, M., Milek, J., Dziembowska, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Preparation+of+polysomal+fractions+from+mouse+brain+synaptoneurosomes+and+analysis+of+polysomal-bound+mrnas.">Preparation of polysomal fractions from mouse brain synaptoneurosomes and analysis of polysomal-bound mrnas.</a> Journal of Neuroscience Methods. 293, 226-233 (2018).</li><li>He, S. L., Green, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Polysome+analysis+of+mammalian+cells.">Polysome analysis of mammalian cells.</a> Methods in Enzymology. 530, 183-192 (2013).</li><li>Molotski, N., Soen, Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Differential+association+of+micrornas+with+polysomes+reflects+distinct+strengths+of+interactions+with+their+mrna+targets.">Differential association of micrornas with polysomes reflects distinct strengths of interactions with their mrna targets.</a> RNA. 18, 1612-1623 (2012).</li><li>Maroney, P. A., Yu, Y., Fisher, J., Nilsen, T. 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D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Human+let-7a+mirna+blocks+protein+production+on+actively+translating+polyribosomes.">Human let-7a mirna blocks protein production on actively translating polyribosomes.</a> Nature Structural and Molecular Biology. 13, 1108-1114 (2006).</li><li>Kim, J., Krichevsky, A., Grad, Y., Hayes, G. D., Kosik, K. S., Church, G. M., Ruvkun, G. <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+many+micrornas+that+copurify+with+polyribosomes+in+mammalian+neurons.">Identification of many micrornas that copurify with polyribosomes in mammalian neurons.</a> Proceedings of the National Academy of Sciences of the United States of America. , 360-365 (2004).</li><li>Androsavich, J. R., Chau, B. N., Bhat, B., Linsley, P. S., Walter, N. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Disease-linked+microrna-21+exhibits+drastically+reduced+mrna+binding+and+silencing+activity+in+healthy+mouse+liver.">Disease-linked microrna-21 exhibits drastically reduced mrna binding and silencing activity in healthy mouse liver.</a> RNA. 18, 1510-1526 (2012).</li><li>Kraushar, M. L., Thompson, K., Wijeratne, H. R., Viljetic, B., Sakers, K., Marson, J. W., Kontoyiannis, D. L., Buyske, S., Hart, R. P., Rasin, M. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Temporally+defined+neocortical+translation+and+polysome+assembly+are+determined+by+the+rna-binding+protein+hu+antigen+r.">Temporally defined neocortical translation and polysome assembly are determined by the rna-binding protein hu antigen r.</a> Proceedings of the National Academy of Sciences of the United States of America. , E3815-E3824 (2014).</li><li>McClatchy, D. B., Ma, Y., Liu, C., Stein, B. D., Martinez-Bartolome, S., Vasquez, D., Hellberg, K., Shaw, R. J., Yates, J. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Pulsed+azidohomoalanine+labeling+in+mammals+(palm)+detects+changes+in+liver-specific+lkb1+knockout+mice.">Pulsed azidohomoalanine labeling in mammals (palm) detects changes in liver-specific lkb1 knockout mice.</a> Journal of Proteome Research. 14, 4815-4822 (2015).</li><li>Schiapparelli, L. M., McClatchy, D. B., Liu, H. H., Sharma, P., Yates, J. R., Cline, H. T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Direct+detection+of+biotinylated+proteins+by+mass+spectrometry.">Direct detection of biotinylated proteins by mass spectrometry.</a> Journal of Proteome Research. 13, 3966-3978 (2014).</li><li>Wi&#347;niewski, J. R., Zougman, A., Nagaraj, N., Mann, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Universal+sample+preparation+method+for+proteome+analysis.">Universal sample preparation method for proteome analysis.</a> Nature Methods. 6, 359-362 (2009).</li><li>Rajalingam, D., Loftis, C., Xu, J. J., Kumar, T. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Trichloroacetic+acid-induced+protein+precipitation+involves+the+reversible+association+of+a+stable+partially+structured+intermediate.">Trichloroacetic acid-induced protein precipitation involves the reversible association of a stable partially structured intermediate.</a> Protein Science. 18, 980-993 (2009).</li><li>Fic, E., Kedracka-Krok, S., Jankowska, U., Pirog, A., Dziedzicka-Wasylewska, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Comparison+of+protein+precipitation+methods+for+various+rat+brain+structures+prior+to+proteomic+analysis.">Comparison of protein precipitation methods for various rat brain structures prior to proteomic analysis.</a> Electrophoresis. 31, 3573-3579 (2010).</li><li>Sashital, D. G., Greeman, C. A., Lyumkis, D., Potter, C. S., Carragher, B., Williamson, J. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+combined+quantitative+mass+spectrometry+and+electron+microscopy+analysis+of+ribosomal+30s+subunit+assembly+in+e.+Coli.">A combined quantitative mass spectrometry and electron microscopy analysis of ribosomal 30s subunit assembly in e. Coli.</a> Elife. 3, (2014).</li><li>Liang, S., Bellato, H. M., Lorent, J., Lupinacci, F. C. S., Oertlin, C., van Hoef, V., Andrade, V. P., Roff&#233;, M., Masvidal, L., Hajj, G. N. M., Larsson, O. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Polysome-profiling+in+small+tissue+samples.">Polysome-profiling in small tissue samples.</a> Nucleic Acids Research. 46, e3 (2018).</li></ol>

Polysome profile analysis allows for the study of protein translation by analyzing the translational state of a specific mRNA or the whole transcriptome6,7. It is also of great help when local translation needs to be studied such as synaptosomes8. Traditionally, this method involves the separation of mono- and polyribosomes and the associated mRNAs on a sucrose gradient which could be coupled with genomic or proteomic techniques to obtain ...

The heart responds to the injury of ischemia (I) and reperfusion (R) in a dynamic fashion. However, there is little insight into acute changes in protein synthesis during the response. To address this, we took advantage of the well-established method of polysome profiling1 to identify changes in protein abundance that reflect redistribution of ribosomes and translational regulatory factors from cytosol to polysomes, and the increase in newly synthesized proteins (NSPs). In the setting of I/R, the increase in new protein synthesis occurs in a time frame that is inconsistent with transcription of new mRNAs2; moreover, discordance between mRNA expression levels and protein abundance has been reported3. For these reasons, we chose to analyze the changes in the dynamic proteome as reflected by protein translation. To do this, we quantify mRNA in the polysome fractions, and analyze the protein composition in the polysome fractions. Finally, because microRNAs (miRs) regulate availability of mRNAs for translation and can interfere with efficiency of protein translation4,5, we examined the distribution of miRs in the polysome fractions, focusing on the response to I/R.
We chose to use the isolated mouse Langendorff perfusion model and harvested tissue under basal conditions of continuous perfusion, after 30 min global no-flow ischemia, and after 30 min of ischemia followed by 30 min of reperfusion. We then solubilized the heart tissue and separated polysomes over a sucrose gradient, followed by proteomic analysis and selective detection of mRNAs and miRNAs by PCR and microarray, respectively. This combination of methods represents a powerful approach to understanding the dynamic proteome, enabling simultaneous detection of mRNA, miRNA, and NSPs, as well as the redistribution of regulatory proteins, miRNA, and mRNA between nontranslating fractions, low-efficiency polysomes, and high-efficiency polysomes (see Figure 1). Insights into the dynamic regulation of this process will be extended by further analysis of phosphorylation of key regulatory factors such as eIF2&#945; or mTOR. These individual steps are now described in detail.

<table>
	<tbody>
		<tr>
			<td>Pentobarbital</td>
			<td>Vortech Phamaceuticals</td>
			<td>9373</td>
			<td>for euthansia</td>
		</tr>
		<tr>
			<td>Heparin</td>
			<td>Sagent</td>
			<td>103424</td>
			<td>used in langendorff preparation</td>
		</tr>
		<tr>
			<td>forceps</td>
			<td>Fine Science Tools</td>
			<td>91110-10</td>
			<td>used to hang the heart</td>
		</tr>
		<tr>
			<td>Langendorff system</td>
			<td>Radnoti + home made</td>
			<td>n/a</td>
			<td>A &#39;four heart&#39; system consisting of custom blown glass, tubing and water baths</td>
		</tr>
		<tr>
			<td>NaCl</td>
			<td>Sigma</td>
			<td>S7653-5KG</td>
			<td>Krebs buffer and Sucrose gradient</td>
		</tr>
		<tr>
			<td>KCl</td>
			<td>Sigma</td>
			<td>P5405</td>
			<td>Krebs buffer and Lysis buffer</td>
		</tr>
		<tr>
			<td>KH2PO4</td>
			<td>Sigma</td>
			<td>P-5504</td>
			<td>Krebs buffer</td>
		</tr>
		<tr>
			<td>MgSO4</td>
			<td>Sigma</td>
			<td>M7774-500G</td>
			<td>Krebs buffer</td>
		</tr>
		<tr>
			<td>Glucose</td>
			<td>Sigma</td>
			<td>G5767</td>
			<td>Krebs buffer</td>
		</tr>
		<tr>
			<td>CaCl2</td>
			<td>Sigma</td>
			<td>C1016-500G</td>
			<td>Krebs buffer</td>
		</tr>
		<tr>
			<td>Sucrose powder</td>
			<td>Sigma</td>
			<td>S0389-1KG</td>
			<td>Sucrose gradient</td>
		</tr>
		<tr>
			<td>MgCl2</td>
			<td>Sigma</td>
			<td>208337</td>
			<td>Sucrose gradient and Lysis buffer</td>
		</tr>
		<tr>
			<td>Tris-base</td>
			<td>Sigma</td>
			<td>T1503-1KG</td>
			<td>Sucrose gradient and Lysis buffer</td>
		</tr>
		<tr>
			<td>Xylene Cyanole</td>
			<td>Sigma</td>
			<td>X-4126</td>
			<td>Sucrose gradient</td>
		</tr>
		<tr>
			<td>Cycloheximide</td>
			<td>Sigma-aldrich</td>
			<td>239763</td>
			<td>Sucrose gradient and Lysis buffer</td>
		</tr>
		<tr>
			<td>RNaseOUT</td>
			<td>Life Technologies</td>
			<td>C00019</td>
			<td>RNAse inhibitor for Lysis buffer</td>
		</tr>
		<tr>
			<td>Igepal CA-360 (NP40)</td>
			<td>Sigma</td>
			<td>I3021</td>
			<td>Lysis buffer</td>
		</tr>
		<tr>
			<td>Protease Inhibitor Cocktail tablets, EDTA free</td>
			<td>Roche</td>
			<td>5056489001</td>
			<td></td>
		</tr>
		<tr>
			<td>Tube, Thinwall, Ultra-Clear, 13.2 mL, 14 x 89 mm</td>
			<td>Beckman Coulter</td>
			<td>344059</td>
			<td></td>
		</tr>
		<tr>
			<td>Ultracentrifuge</td>
			<td>Beckman</td>
			<td>LE-80K</td>
			<td>Ultracentrifugation of the gradients</td>
		</tr>
		<tr>
			<td>Rotor</td>
			<td>Beckman</td>
			<td>SW41</td>
			<td>Ultracentrifugation of the gradients</td>
		</tr>
		<tr>
			<td>Biologic LP (pump)</td>
			<td>Biorad</td>
			<td>731-8300</td>
			<td>Fractionation of the gradients</td>
		</tr>
		<tr>
			<td>BioFrac</td>
			<td>Biorad</td>
			<td>741-0002</td>
			<td>Fractionation of the gradients</td>
		</tr>
		<tr>
			<td>Eppendorf RNA/DNA LoBind microcentrifuge tubes, 2 mL tube</td>
			<td>Sigma</td>
			<td>Z666513-100EA</td>
			<td>Gradient fraction and RNA extraction</td>
		</tr>
		<tr>
			<td>TRIzol Reagent</td>
			<td>Life technologies</td>
			<td>AM9738</td>
			<td>RNA extraction</td>
		</tr>
		<tr>
			<td>Luciferase Control RNA</td>
			<td>Promega</td>
			<td>L4561</td>
			<td>RNA extraction</td>
		</tr>
		<tr>
			<td>Chloroform</td>
			<td>Fisher Scientific</td>
			<td>C606-4</td>
			<td>RNA extraction</td>
		</tr>
		<tr>
			<td>Glycogen, RNA grade</td>
			<td>Thermo Fisher Scientific</td>
			<td>R0551</td>
			<td>RNA extraction</td>
		</tr>
		<tr>
			<td>Isopropanol</td>
			<td>Sigma</td>
			<td>I9516</td>
			<td>RNA extraction</td>
		</tr>
		<tr>
			<td>Ethanol</td>
			<td>Sigma</td>
			<td>E7023-1L</td>
			<td>RNA extraction</td>
		</tr>
		<tr>
			<td>iScript cDNA Synthesis Kit</td>
			<td>BioRad</td>
			<td>170-8891</td>
			<td>Reverse transcription</td>
		</tr>
		<tr>
			<td>iTaq Universal SYBR Green Supermix</td>
			<td>BioRad</td>
			<td>175-5122</td>
			<td>Quantative PCR</td>
		</tr>
		<tr>
			<td>miRNeasy Micro Kit (50)</td>
			<td>Qiagen</td>
			<td>217084</td>
			<td>Kit for total RNA isolation</td>
		</tr>
		<tr>
			<td>miScript II RT Kit (50)</td>
			<td>Qiagen</td>
			<td>218161</td>
			<td>Kit for miRNA reverse transcription</td>
		</tr>
		<tr>
			<td>miScript Sybr Green PCR Kit (200)</td>
			<td>Qiagen</td>
			<td>218073</td>
			<td>Kit for real-time PCR expression analysis of miRNAs</td>
		</tr>
		<tr>
			<td>Centrifuge 5424R</td>
			<td>Eppendorf</td>
			<td></td>
			<td>For centrifugation of 1.5ml or 2.0ml tubes at different temperatures. Max speed - 21130g</td>
		</tr>
		<tr>
			<td>Centrifuge 5810R</td>
			<td>Eppendorf</td>
			<td></td>
			<td>For real-time PCR plate centrifugation at different temperatures. Max speed - 2039g</td>
		</tr>
		<tr>
			<td>My Cycler Thermal Cycler</td>
			<td>Bio-Rad</td>
			<td></td>
			<td>For reverse transcription</td>
		</tr>
		<tr>
			<td>CFX96 Real-Time System/C1000 Touch Thermal Cycler</td>
			<td>Bio-Rad</td>
			<td></td>
			<td>For real-time PCR analysis</td>
		</tr>
		<tr>
			<td>miRNeasy Serum/Plasma Spike-in Control</td>
			<td>Qiagen</td>
			<td>219610</td>
			<td>For quality control of RNA isolation</td>
		</tr>
		<tr>
			<td>Hard-Shell 96-Well PCR Plates, low profile, thin wall, skirted, green/clear</td>
			<td>Bio-Rad</td>
			<td>HSP9641</td>
			<td>For real-time PCR analysis</td>
		</tr>
		<tr>
			<td>Microseal &#39;B&#39; PCR Plate Sealing Film, adhesive, optical</td>
			<td>Bio-Rad</td>
			<td>MSB1001</td>
			<td>For real-time PCR plate sealing</td>
		</tr>
		<tr>
			<td>Research plus Single-Channel Pipette, Gray; 0.5-10 &#181;L</td>
			<td>Eppendorf</td>
			<td>UX-24505-02</td>
			<td>For pipetting</td>
		</tr>
		<tr>
			<td>PIPETMAN Classic Pipets, P20</td>
			<td>Gilson</td>
			<td>F123600G</td>
			<td>For pipetting</td>
		</tr>
		<tr>
			<td>PIPETMAN Classic Pipets, P200</td>
			<td>Gilson</td>
			<td>F144565</td>
			<td>For pipetting</td>
		</tr>
		<tr>
			<td>Rainin L-1000XLS Pipet-Lite XLS LTS Pipette 100-1000 &#181;L</td>
			<td>Gilson</td>
			<td>17011782</td>
			<td>For pipetting</td>
		</tr>
		<tr>
			<td>Glycogen, RNA grade</td>
			<td>Thermo Fisher Scientific</td>
			<td>R0551</td>
			<td>Improves total RNA isolation efficiency</td>
		</tr>
		<tr>
			<td>Posi-Click 1.7 mL Tubes, natural color</td>
			<td>Denville</td>
			<td>C2170</td>
			<td>RNA isolation and storage; reagent mix</td>
		</tr>
		<tr>
			<td>Thermal Cycling Tubes -0.2 mL Individual Caps, Standard 0.2 mL tubes with optically</td>
			<td>Denville</td>
			<td>C18098-4 (1000910)</td>
			<td>Reverse transcription reaction</td>
		</tr>
		<tr>
			<td>Sharp 10 Precision barrier Tips</td>
			<td>Denville</td>
			<td>P1096-FR</td>
			<td>For pipetting</td>
		</tr>
		<tr>
			<td>Sharp 20 Precision barrier Tips</td>
			<td>Denville</td>
			<td>P1121</td>
			<td>For pipetting</td>
		</tr>
		<tr>
			<td>Sharp 200 Precision barrier Tips</td>
			<td>Denville</td>
			<td>P1122</td>
			<td>For pipetting</td>
		</tr>
		<tr>
			<td>Tips LTS 1 mL Filter</td>
			<td>Rainin</td>
			<td>RT-L1000F</td>
			<td>For pipetting</td>
		</tr>
		<tr>
			<td>miScript Primer Assay (200)</td>
			<td>Qiagen</td>
			<td>(it changes according to the miRNA)</td>
			<td>For real-time PCR analysis</td>
		</tr>
		<tr>
			<td>Gradient Master ver 5.3 Model 108</td>
			<td>BioComp Instruments</td>
			<td></td>
			<td>For preparation of sucrose gradients</td>
		</tr>
		<tr>
			<td>trichloroacetic acid</td>
			<td>Sigma Aldrich</td>
			<td>T6399</td>
			<td></td>
		</tr>
		<tr>
			<td>acetone</td>
			<td>Sigma Aldrich</td>
			<td>650501</td>
			<td></td>
		</tr>
		<tr>
			<td>Tris hydrochloride</td>
			<td>Amresco</td>
			<td>M108</td>
			<td></td>
		</tr>
		<tr>
			<td>dithiothreitol</td>
			<td>Fisher Scientific</td>
			<td>BP172</td>
			<td></td>
		</tr>
		<tr>
			<td>iodoacetamide</td>
			<td>Gbiosciences</td>
			<td>RC-150</td>
			<td></td>
		</tr>
		<tr>
			<td>sequencing grade modified trypsine, porcine</td>
			<td>Promega</td>
			<td>V5111</td>
			<td></td>
		</tr>
		<tr>
			<td>ammonium bicarbonate</td>
			<td>BDH</td>
			<td>BDH9206</td>
			<td></td>
		</tr>
		<tr>
			<td>formic acid, Optima LC/MS</td>
			<td>Fisher Chemical</td>
			<td>A117</td>
			<td></td>
		</tr>
		<tr>
			<td>methanol, Optima LC/MS</td>
			<td>Fisher Chemical</td>
			<td>A454</td>
			<td></td>
		</tr>
		<tr>
			<td>acetonitrile, Optima LC/MS</td>
			<td>Fisher Chemical</td>
			<td>A996</td>
			<td></td>
		</tr>
		<tr>
			<td>Protein LoBind tubes 0.5 mL</td>
			<td>Eppendorf AG</td>
			<td>22431064</td>
			<td></td>
		</tr>
		<tr>
			<td>Protein LoBind tubes 1.5 mL</td>
			<td>Eppendorf AG</td>
			<td>22431081</td>
			<td></td>
		</tr>
		<tr>
			<td>HLB &#181;Elution plate 30 &#181;m</td>
			<td>Oasis</td>
			<td>186001828BA</td>
			<td></td>
		</tr>
		<tr>
			<td>SpeedVac concentrator</td>
			<td>Thermo Scientific</td>
			<td>Savant SPD2010</td>
			<td></td>
		</tr>
		<tr>
			<td>sonicator</td>
			<td>Qsonica</td>
			<td>Oasis180</td>
			<td></td>
		</tr>
		<tr>
			<td>centrifuge</td>
			<td>Thermo Scientific</td>
			<td colspan="2">Sorvall Legend micro 21R</td>
		</tr>
		<tr>
			<td>LC trap column PepMap 100 C18</td>
			<td>Thermo Scientific</td>
			<td>160454</td>
			<td></td>
		</tr>
		<tr>
			<td>LC separation column PepMap RSLC C18</td>
			<td>Thermo Scientific</td>
			<td>164536</td>
			<td></td>
		</tr>
		<tr>
			<td>mass spectrometer</td>
			<td>Thermo Scientific</td>
			<td colspan="2">Orbitrap Elite ion trap mass spectrometer</td>
		</tr>
		<tr>
			<td>MSConvert software</td>
			<td>ProteoWizard Toolkit</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Sorcerer-SEQUEST software</td>
			<td>Sage-N Research, Inc.</td>
			<td></td>
			<td></td>
		</tr>
	</tbody>
</table>

dynamic proteomic and mirna analysis of polysomes from isolated mouse heart after langendorff perfusion

Studies in dynamic changes in protein translation require specialized methods. Here we examined changes in newly-synthesized proteins in response to ischemia and reperfusion using the isolated perfused mouse heart coupled with polysome profiling. To further understand the dynamic changes in protein translation, we characterized the mRNAs that were loaded with cytosolic ribosomes (polyribosomes or polysomes) and also recovered mitochondrial polysomes and compared mRNA and protein distribution in the high-efficiency fractions (numerous ribosomes attached to mRNA), low-efficiency (fewer ribosomes attached) which also included mitochondrial polysomes, and the non-translating fractions. miRNAs can also associate with mRNAs that are being translated, thereby reducing the efficiency of translation, we examined the distribution of miRNAs across the fractions. The distribution of mRNAs, miRNAs, and proteins was examined under basal perfused conditions, at the end of 30 min of global no-flow ischemia, and after 30 min of reperfusion. Here we present the methods used to accomplish this analysis&#8212;in particular, the approach to optimization of protein extraction from the sucrose gradient, as this has not been described before&#8212;and provide some representative results.

mRNA analysis 
mRNA results can be expressed as a distribution of a particular mRNA in each fraction (Figure 3A); for quantification, combine polyribosomal translating fractions and compare to the non-translating fraction (Figure 3B), presenting a ratio of mRNA abundance in translating to nontranslating fractions. Additional information is gained by examining the high efficiency polysome fractions separately from lo...

Watch this Scientific Journal Video about Dynamic Proteomic and miRNA Analysis of Polysomes from Isolated Mouse Heart After Langendorff Perfusion at JoVE.com

Dynamic Proteomic and miRNA Analysis of Polysomes from Isolated Mouse Heart After Langendorff Perfusion

Here we present a protocol to perform polysome profiling on the isolated perfused mouse heart. We describe methods for heart perfusion, polysome profiling, and analysis of the polysome fractions with respect to mRNAs, miRNAs, and the polysome proteome.

Studies in dynamic changes in protein translation require specialized methods. Here we examined changes in newly-synthesized proteins in response to ...

This method can help answer key questions about dynamic protein synthesis and the proteome involved in the process. This technique allows identification of the mRNAs that are being selected for translation, the microRNAs that can participate in the process and interfere with translation, and the proteins that contribute to protein translation or are themselves being translated. This method can provide insight into cardiac responses to stress, but can also be applied to the study of acute responses to stress in other organs.Demonstrating the procedure will be Miroslava Stastna, a project scientist from Jennifer Van Eyk's laboratory. On the day of the experiment, fill the left compartment of a gradient mixer with five milliliters of 15%sucrose gradient solution, and fill the right compartment with five milliliters of 50%sucrose gradient solution. Open the tap and switch on the pump to stir the two small compartments with a magnetic stirrer, and use a tube linked to the second tap to allow the mixed sucrose solutions to flow into a single ultracentrifuge tube with thin walls on ice.Next, homogenize the fresh or frozen heart tissue with a POLYTRON in filtered lysis buffer for 15 seconds on ice. At the end of the incubation, centrifuge the lysate to remove the insoluble material, and harvest the supernatant. Set aside 50 microliters of the supernatant for protein determination, RNA isolation, and RNA integrity analysis, and layer 100 to 500 microliters of the remaining supernatant over the gradient solution.Use fresh lysis buffer to balance the volumes between the two gradient tubes, and ultracentrifuge the samples in an ultracentrifuge with a swinging bucket rotor. Be very careful not to disturb the sucrose gradient before or after centrifugation. To collect the gradients, program the fraction collector to discard the first three minutes of collection and to collect the heavy, light, and non-translating fractions at the speed of one milliliter per minute in 17 fractions from four to 19 minutes with continuous monitoring of the absorbance at 254 nanometers.Place each fraction on ice as soon as it is collected. Then store the samples at minus 80 degrees Celsius, if they are not being processed immediately. To extract proteins from the polysome fractions, combine the collected sucrose fractions into three final fractions, and mark the fractions as heavy, light, and non-translating.Mix 0.5 milliliters of each sample with 60 microliters of 100%trichloroacetic acid, or TCA. Incubate the fractions overnight at minus 20 degrees Celsius in the dark. The next morning, thaw the samples on ice before pelleting the proteins by centrifugation.Discard the supernatants, and wash the pellets two times with 0.5 milliliters of minus 20 degrees Celsius chilled acetone per centrifugation. Make sure pellet, after TCA precipitation, is completely dissolved, using pulse sonication to ensure complete solubilization, as necessary. Air dry the pellets after the last wash before resuspension in 360 microliters of Tris-HCl buffer.Then add 40 microliters of dithiothreitol for a 45-minute incubation at 55 degrees Celsius with shaking. At the end of the incubation, add 50 microliters of iodoacetamide to the samples for a 30-minute incubation on the shaker at room temperature, protected from light, followed by digestion of the samples with a one-to-50 weight-to-weight trypsin-to-protein ratio for an overnight shaking incubation at 37 degrees Celsius. The next morning, after cooling, briefly centrifuge the samples, and adjust the pH to two to three with 10%formic acid to quench the trypsin activity.To desalt the samples, first condition the sorbent in the wells of a 96-well plate with 200 microliters of methanol three times, followed by conditioning with 200 microliters of 0.1%formic acid per well three times. Next, load the samples onto each well, and wash the samples three times with 200 microliters of 0.1%formic acid per wash. Using gravitation, followed by low vacuum, elute the samples with 100 microliters of 0.1%formic acid in 50%acetonitrile two times into one low protein retention 0.5-milliliter tube per sample.Then use a concentrator to evaporate the sample eluates to dryness, and reconstitute each tryptic peptide pellet in 50 to 100 microliters of 0.1%formic acid for mass spectrometry analysis. mRNA analysis can be performed to assess the distribution of a particular mRNA of interest in each fraction or for quantification and comparison of the combined polyribosomal translating fractions to the non-translating fraction as a ratio of mRNA abundance each fraction. For example, here, the changes in mRNA distribution across the translating and non-translating fractions after mouse heart subjection to ischemia or ischemia reperfusion, compared to sham heart treatment are shown.In this representative experiment, the analysis of a subset of microRNAs in the pooled heavy fractions revealed that 22 microRNAs were associated with polysomes during ischemia, nine were associated during ischemia and reperfusion, and seven were common to both conditions, demonstrating that the association of microRNAs is dynamic in response to the stresses of ischemia and reperfusion. Further, the majority of mitochondrial ribosomal proteins were identified in the light fraction, and the majority of the cytosolic ribosomal proteins were identified commonly in both the heavy and light fractions. While attempting this procedure, it's important to remember to be very careful with the sucrose gradient.TCA precipitation for extraction of proteins from polysome fractions was selected in our workflow based on both the ability to process the fraction with high concentration of sucrose and the number of proteins identified by mass spectrometry. Generally, individuals new to this method may struggle because of the challenges associated with the reproducibility of the sucrose gradient. TCA precipitation is advantageous since only small volumes is needed to precipitate the proteins, the pellet is visibile at the tube bottom, and there is no accumulation of sucrose during precipitation.

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Biochemistry

8.5K vistas.  Cedars-Sinai Medical Center. This method can help answer key questions about dynamic protein synthesis and the proteome involved in the process. This technique allows identification of the mRNAs that are being selected for translation, the microRNAs that can participate in the process and interfere with translation, and the proteins that contribute to protein translation or are themselves being translated. This method can provide insight into cardiac responses to stress, but can also be applied to the study of acute resp...