Diese Arbeit wird von der University of Virginia, der University of Virginia Cancer Center und The Thomas F. und Kate Miller Jeffress Memorial Trust unterstützt. Wir danken den James E. Darnell Lab (Rockefeller University) der Robert Ross Lab (Fordham University) für die Zell-Linien.

PLANUNG Der Tag vor einem ChIP Experiment geplant ist, sollten die Zellen kultiviert, so dass eine ausreichende Anzahl zur Verfügung steht. Angenommen, dass jeder ChIP-Assay wird ~ 1-1,5 x 10 7 Zellen benötigen. Immer Plan, sowohl die negative (IgG) und positive (Pan-Histon-Antikörper) Kontrollen und doppelte Experimente zu tun. Tipp - 2FTGH Zellen benötigt jeder ChIP Assay etwa ein 15 cm Gewebe Kulturschale bei 80% Konfluenz. TEIL 1: PREPARE Chromatin und PERFORM ChIP <ol><li> Entfernen Kulturmedien und induzieren Zellen für die Zeiten mit 20 ml 10% kosmischen Kälberserum (CCS) / DMEM mit IFN-gamma bei 5 ng / mL benötigt. Ersetzen Sie die Medien auf die induzierten Platten mit 20 ml 10% CCS / DMEM sowie. </li><li> In einer Abzugshaube, fügen Sie 540 ul 37% Formaldehyd und 20 ml Medium (1% Endkonzentration) in der 15 cm Schüssel. Tip - Tilt Platte und fügen Sie die Formaldehyd zu den Medien Pool - dann Felsplatte, um es gleichmäßig verteilt. </li><li> Lassen Vernetzung für 10 Minuten bei Raumtemperatur ablaufen. </li><li> Add Glycin bis 0,125 M Endkonzentration, um die Vernetzung zu stoppen. </li><li> Vakuum absaugen Medien und waschen Sie die Zellen einmal mit 10 mL eiskaltem Phosphat-gepufferter Kochsalzlösung (PBS). </li><li> Sammeln Sie Zellen mit einem Zellschaber in ~ 7 mL PBS und kombinieren Zellen (von 6 Platten), die identisch in 50 mL konischen Rohr auf Eis behandelt wurden. </li><li> Zentrifuge (Beckman Coutler Allegra 12-R Zentrifuge) bei 1800 rpm bei 4 ° C für 5 Minuten und saugen Sie den PBS. Tipp - Snap freeze das Zellpellet wenn hier anzuhalten und bei -80 ° C. </li><li> Zellpellet in 4 ml Schwellung Buffer (25 mM HEPES pH 7,8, 1,5 mM MgCl 2, 10 mM KCl, 0,1% NP40. Hinzufügen 1 mM DTT, Complete Protease-Inhibitoren und Chill auf Eis vor dem Gebrauch) und Transfer zu einem 15 mL konischen Rohr. Tip - Diese Schwellung Puffervolumen ist angemessen für einen 6-Platte Pooling (~ 6-9 x 10 7 Zellen). Mehr oder weniger Puffer ändern könnte die douncing Effizienz. </li><li> Inkubieren Sie die Zellsuspension auf Eis für 10 Minuten. </li><li> Transfer-Suspension in eine vorgekühlte 15 ml douncer (Wheaton) und Dounce 20 Hübe mit Pistill A. </li><li> Transfer dounced Zellen wieder in eine 15 ml konische Röhrchen auf Eis. </li><li> Zentrifugation bei 2500 rpm für 5 Minuten bei 4 ° C und den Überstand verwerfen. </li><li> Resuspendieren Kernpellet (~ 200 ul von 6 Platten) in 3 mL (15 Pellet-Volumen) der Beschallung Buffer (50 mM HEPES pH 7,9, 140 mM NaCl, 1 mM EDTA, 1% Triton X-100, 0,1% Natriumdesoxycholat, 0,1% SDS. hinzufügen Komplett-Protease-Inhibitoren und Chill auf Eis kurz vor dem Gebrauch). Tipp - Das Ultraschall Puffervolumen ist angemessen für einen 6-Platte Pooling (~ 6-9 x 10 7 Zellen). Mehr oder weniger Puffer ändern könnte die Beschallung Effizienz. </li><li> Ultraschallbad Kerne Suspension auf Eis für 10 Zyklen (20 Sekunden on/40 Sekunden aus / Einstellung der Amplitude von 8) mit einem Misonix Sonicator 3000 mit der Mikrospitze ausgestattet. Dies führt in der Regel Chromatinfragmenten durchschnittlich 200-1000 bps in der Größe. Tip - Da sonicators variieren, die Beschallung Effizienz muss empirisch ermittelt werden. Dazu nehmen Aliquots von 20 ul vor Beschallung und nach jeder Beschallung Zyklus. Hitze dieser Proben bei 65 ° C für 4 Stunden. Fügen Sie DNA-Ladepuffer und Ausführen eines Standard 1% Agarose / TBE-Gel, um DNA-Fragmente sichtbar zu machen.) </li><li> Transfer beschallt Material zu einem SS34-Zentrifugenröhrchen und Zentrifuge für 20 Minuten bei 4 ° C bei 13000 rpm in einem SS34-Rotor (Sorvall RC6 Plus-Zentrifuge), um Pellets, was ist in der Regel eine kleine Menge von Zelltrümmern. </li><li> Vorsichtig den Überstand in ein konisches 15 ml Röhrchen auf Eis. </li><li> Pre-clear, indem 360 ul Salmon Sperm DNA / Protein A oder G Agaroseperlen Gülle und Schütteln bei 4 ° C für mindestens 30 Minuten. Tipp - Dieser Schritt nimmt das Rauschen im Test, die von nicht-spezifische Bindung Ereignissen beruht. </li><li> Zentrifugation bei 1000 rpm bei 4 ° C für 5 Minuten auf dem Pellet Agaroseperlen. </li><li> Transfer bereits geklärten Überstand in einen anderen 15 ml konische Röhrchen auf Eis. </li><li> Messen Sie die A260-Einheiten der pre-cleared Chromatin und die Lautstärke mit Ultraschall Buffer zu vier (4) A260-Einheiten (0,2 mg / mL davon 1 A260 Einheit = 0,050 mg / ml) Tipp - Um die A260-Einheiten zu messen, verwässern 10 ul bereits geklärten Chromatin in 190 ul DDW; blank Spektralphotometer mit 10 l Ultraschall-Puffer in 190 ul DDW. </li><li> Sparen Sie 75 ul des Chromatins (bei 4 A260-Einheiten) als Eingangs-Sample und lagern bei 20 ° C bis zu seiner Vernetzungen umkehren. Tipp - Dieser Schritt ist entscheidend für die Datenanalyse. Vernachlässigen Sie nicht auf den Eingang Aliquot nehmen. </li><li> Aliquot der vorbereiteten Chromatin auf 1,7 mL Mikrozentrifugenröhrchen auf ice als 1 mL Aliquots. Tipp - Wenn hier anzuhalten, Snap einfrieren vorbereitet Chromatin auf Trockeneis und bei -80 ° C. NB: gespeichert Chromatin abbauen kann, die weniger als optimale Ergebnisse, so vermeiden, wenn möglich. </li><li> Fügen Sie die ChIP-grade-Antikörper gegen den induzierten und nicht-induzierten Proben-Sets in zweifacher Ausfertigung. Add IgG (2 g) und pan Histone H3 Antikörper (15 ul) als die negativen und positiven Kontrollen zur induzierten und nicht-induzierten Proben-Sets. Tipp - Die Menge des Antikörpers zu nutzen muss empirisch ermittelt werden oder auf der Lieferanten Produktblatt vorgeschlagenen Mengen. In der Regel 1-2 ug aus einem Chip-grade Antikörper gut funktioniert. Das entsprechende Volumen muss empirisch für Antikörper, die als Serum versorgt sind, bestimmt werden. </li><li> Rock Alle Rohre über Nacht bei 4 ° C. </li></ol> TEIL 2: COLLECT Immunkomplexen <ol><li> Add 60 ul Salmon Sperm DNA / Protein A oder Protein G Agarose-Beads Gülle zu allen Rohren. Tipp: Verwenden Protein A für polyklonalen Kaninchen-Antikörper und Protein G für monoklonalen Maus-Antikörper. </li><li> Rock bei 4 ° C für mindestens 60 Minuten. </li><li> Pellet die Immunkomplexe (Agaroseperlen) durch microfuging sanft bei 2000 rpm bei 4 ° C für 3 Minuten. </li><li> Den Überstand aspirieren. </li><li> Waschen Sie die Immunkomplexe mit 1 ml jedes der folgenden Waschpuffer für 10 Minuten unter Schütteln bei 4 ° C. Microfuge für 3 Minuten bei 2000 rpm bei 4 ° C zwischen jedem Waschen und Absaugen des Überstandes. Keep Proben auf Eis gekühlt. Add PMSF kurz vor dem Gebrauch. <ul><li> Low Salt Wash - 0,1% SDS, 1% Triton X-100, 2 mM EDTA, 20 mM Tris-Cl, pH 8,0, 150 mM NaCl, 1 mM PMSF </li><li> Hohe Salt Wash - 0,1% SDS, 1% Triton X-100, 2 mM EDTA, 20 mM Tris-Cl, pH 8,0, 500 mM NaCl, 1 mM PMSF </li><li> LiCl Wash - 0,25 M LiCl, 1% NP-40, 1% Natriumdesoxycholat, 1 mM EDTA, 10 mM Tris-Cl, pH 8,0, 1 mM PMSF </li><li> TE Wash - zwei Waschgänge mit TE-Puffer -10 mm Tris-Cl, pH 8,0, 1 mM EDTA, 1 mM PMSF </li></ul></li><li> Entfernen Sie die letzten TE-Puffer zu waschen und die Perlen, 500 ul Elutionspuffer (50 mM Tris-Cl, pH 8,0, 10 mM EDTA, 1% SDS). Tipp - Der Elutionspuffer sollte frisch zubereitet werden. </li><li> Vortex zu Agaroseperlen in Elutionspuffer und Wärme-Mix für 30 Minuten bei 65 ° C. Tipp - Jedes Röhrchen mindestens alle 10 Minuten während dieser 30 Minuten. </li><li> Microfuge für 30 Sekunden bei 2000 rpm und Transfer des Eluenten zu einer neuen Mikrozentrifugenröhrchen. Tipp - Während der Elution auftauen Ihre Eingabe Proben und fügen 500 ul Elutionspuffer auf jeden einzelnen. Fügen Sie diesen Proben in alle Schritte für die Zukunft. </li><li> Add 5 M NaCl auf eine Endkonzentration von 200 mM zu allen Proben und Wirbel. </li><li> Inkubation bei 65 ° C über Nacht (oder mindestens 4 Stunden). </li></ol> TEIL 3: PURIFY ChIP&#39;d UND INPUT DNA <ol><li> Microfuge alle Proben für 30 Sekunden, um Kondensation an Deckeln zu sammeln. </li><li> Add 1μL von RNAse A (10 U / mL) in jedes Röhrchen und inkubieren bei Raumtemperatur für 15 Minuten. </li><li> Fügen Sie 10 ul 0,5 M EDTA, 40 ul 0,5 M Tris-Cl pH 6,5, 2 ul Proteinase K (10 mg / mL) und inkubieren bei 45 ° C für 60 Minuten. Tipp Bereiten Sie einen Master-Mix dieser Reagenzien und fügen 52 ul in jedes Röhrchen. </li><li> Phenol / Chloroform / Isoamylalkohol extrahiert und dann Chloroform / Isoamylalkohol extrahiert die Proben. </li><li> Add 2 ul Glykogen (25 ug / mL) und 0,1 Volumen 3M Na-Acetat pH 5,2 und Wirbel. </li><li> Add 2,5 Volumen 100% Ethanol und vortexen. </li><li> Inkubation bei 20 ° C über Nacht. </li></ol> TEIL 4: Entschlacken ChIP&#39;d UND INPUT DNA FORTSETZUNG <ol><li> Microfuge Proben für mindestens 20 Minuten bei 13000 rpm bei 4 ° C zur Fällung der DNA / Glycogen Pellets. </li><li> Waschen mit DNA / Glykogen-Pellets mit 1 ml 70% Ethanol. </li><li> An der Luft trocknen Pellets oder trocknen schnell in DNA Savant Speed ​​Vakuumzentrifuge. Tip - nicht über trockenem die DNA. </li><li> Resuspendieren DNA / Glykogen-Pellets in 200 ul TE-Puffer. </li><li> DNA (1 ul) ist bereit für die Quantifizierung mittels Real-time PCR. Shop restlichen DNA bei 20 ° C. Tip - Mit mehr als 1 ul DNA kann die real-time PCR Reaktionen hemmen, so Scale-up mit Vorsicht. </li></ol> Teil 5: Repräsentative Ergebnisse: ChIP und Input DNA-Proben werden mit Real-Time PCR 7,8 (Applied Biosystems 7500 Fast Real-Time PCR System) unter Verwendung von Primern spezifisch für die Gen-Locus der Zinsen quantifiziert. Primern, die genomische Sequenz bekannt ist in angereichert werden oder fehlen in der Histon-Modifikationen zu untersuchenden können als positive und negative Kontrollen verwendet werden. Die Daten werden als Prozentsatz der Eingang vorgestellt. Die ChIP Verfahren sollte ganz sein repeated mit drei biologischen Replikaten gemeldet Veränderungen in Histon-Modifikationen sind statistisch signifikant zu gewährleisten. Es gibt mehrere wichtige Aspekte zu berücksichtigen bei der Verwendung von Echtzeit-PCR, DNA, einschließlich Primer-Design, PCR-Effizienz und der geeignete Weg, um den Prozentsatz der Ein-und Normalisierung Verfahren berechnen zu quantifizieren. Wenn Profiling Histonmodifikationen Belegung über ein Gen, muss die PCR-Effizienz werden unter allen Primerpaaren konsistent. Die real-time PCR-System Hersteller kann die erforderlichen Informationen und Unterweisungen. Abbildung 1 zeigt repräsentative Ergebnisse von Chromatin Immunopräzipitation während STAT1 Aktivierung des IRF1 Gen 9, ausgelöst durch IFN-γ. <img src="/files/ftp_upload/2053/2053fig1.jpg" alt="Abbildung 1" /> Abbildung 1. Belegung von STAT1, RNA Polymerase II und H3K36me3 während STAT1 Aktivierung des Gens IRF1 dynamisch. (A, B, C) ​​ChIP mit α-H3K36me3, α-STAT1 und α-Pol II von Chromatin aus 2FTGH Zellen gesammelt mit IFN-γ für 30 Minuten (rote Quadrate), 1,5 Stunden (blaue Kreise), 5 Stunden (induzierte grüne Dreiecke) oder nicht-induzierten (schwarze Rauten). IgG ist der Negativ-Kontrolle (grau Kreuze). (D) Pan H3 die positive Kontrolle ist und zeigt die Histon-Belegung in den Ort in der induzierten (blaue Kreise) und nicht-induzierten Bedingungen (schwarze Rauten). Der Dip ca. -5 bp ist auf die Nukleosomen Erschöpfung, die bei Ablese-Startpunkten gefunden wird.

<ol>
	<li>Levy, D., Darnell, J. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Signalling:+Stats:+transcriptional+control+and+biological+impact.">Signalling: Stats: transcriptional control and biological impact.</a> Nature Reviews Molecular Cell Biology. 3, 651-662 (2002).</li><li>Bromberg, J., Darnell, J. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+role+of+STATs+in+transcriptional+control+and+their+impact+on+cellular+function.">The role of STATs in transcriptional control and their impact on cellular function.</a> Oncogene. 19, 2468-2473 (2000).</li><li>Hu, X., Ivashkiv, L. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cross-regulation+of+signaling+pathways+by+interferon-gamma:+implications+for+immune+responses+and+autoimmune+diseases.">Cross-regulation of signaling pathways by interferon-gamma: implications for immune responses and autoimmune diseases.</a> Immunity. 31, 539-550 (2009).</li><li>Campos, E. I., Reinberg, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Histones:+annotating+chromatin.">Histones: annotating chromatin.</a> Annu Rev Genet. 43, 559-599 (2009).</li><li>Kouzarides, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Chromatin+Modifications+and+Their+Function.">Chromatin Modifications and Their Function.</a> Cell. 128, 693-705 (2007).</li><li>Jenuwein, T., Allis, C. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Translating+the+histone+code.">Translating the histone code.</a> Science. 293, 1074-1080 (2001).</li><li>Wittwer, C. T., Herrmann, M. G., Moss, A. A., Rasmussen, R. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Continuous+fluorescence+monitoring+of+rapid+cycle+DNA+amplification.">Continuous fluorescence monitoring of rapid cycle DNA amplification.</a> Biotechniques. 22 (130-131), 134-138 (1997).</li><li>Higuchi, R., Dollinger, G., Walsh, P. S., Griffith, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Simultaneous+amplification+and+detection+of+specific+DNA+sequences.">Simultaneous amplification and detection of specific DNA sequences.</a> Biotechnology (N Y). 10, 413-417 (1992).</li><li>Kroger, A., Koster, M., Schroeder, K., Hauser, H., Mueller, P. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Activities+of+IRF-1.">Activities of IRF-1.</a> J Interferon Cytokine Res. 22, 5-14 (2002).</li><li>Ross, R. A., Spengler, B. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Human+neuroblastoma+stem+cells.">Human neuroblastoma stem cells.</a> Seminars in cancer biology. 17, 241-247 (2007).</li></ol>

Die ChIP-Protokoll beschrieben wurde erfolgreich im Labor zum Testen mehr als zwanzig verschiedenen Histon-Modifikationen eingesetzt. Darüber hinaus haben wir Änderungen in der Belegung von Transkriptionsfaktoren charakterisiert, Histon-modifizierende Enzyme, Proteine, die Histon-Modifikationen und der RNA Polymerase II Transkription Maschinen zu erkennen, an mehreren IFN-γ induzierten Genen. Wir haben auch das Verfahren verwendet werden, um Veränderungen in Histon-Modifikationen während der Differenzierung von Kre...

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		<div>
		<table border="1">
		<thead>
		<tr>
		<th>Material Name</th>
		<th>Type</th>
		<th>Company</th>
		<th>Catalogue Number</th>
		<th>Comment</th>
		</tr>
		</thead>
		<tbody>
		
<tr>
<td>37% Formaldehyde</td>
<td>&nbsp;</td>
<td>Fisher</td>
<td>BP531-500</td>
<td>&nbsp;</td>
<tr>
<td>Chloroform/Isoamyl alcohol</td>
<td>&nbsp;</td>
<td>Acros</td>
<td>AC32715-5000</td>
<td>&nbsp;</td>
<tr>
<td>Complete Mini Protease Inhibitors</td>
<td>&nbsp;</td>
<td>Roche</td>
<td>1836153</td>
<td>&nbsp;</td>
<tr>
<td>Cosmic Calf Serum</td>
<td>&nbsp;</td>
<td>Hyclone</td>
<td>SH30087.04N</td>
<td>&nbsp;</td>
<tr>
<td>DMEM</td>
<td>&nbsp;</td>
<td>Hyclone</td>
<td>SH30243</td>
<td>&nbsp;</td>
<tr>
<td>DTT</td>
<td>&nbsp;</td>
<td>Sigma</td>
<td>D0632</td>
<td>&nbsp;</td>
<tr>
<td>EDTA</td>
<td>&nbsp;</td>
<td>Fisher</td>
<td>BP118-500</td>
<td>&nbsp;</td>
<tr>
<td>Ethanol</td>
<td>&nbsp;</td>
<td>Pharmco</td>
<td>zp1110EP</td>
<td>&nbsp;</td>
<tr>
<td>Glycine</td>
<td>&nbsp;</td>
<td>Roche</td>
<td>100149</td>
<td>&nbsp;</td>
<tr>
<td>Glycogen</td>
<td>&nbsp;</td>
<td>Roche</td>
<td>901393</td>
<td>&nbsp;</td>
<tr>
<td>HEPES</td>
<td>&nbsp;</td>
<td>Sigma</td>
<td>H3784</td>
<td>&nbsp;</td>
<tr>
<td>IFN-gamma</td>
<td>&nbsp;</td>
<td>R&amp;D Systems</td>
<td>285-IF-100</td>
<td>&nbsp;</td>
<tr>
<td>IgG</td>
<td>&nbsp;</td>
<td>Jackson Immunoresearch</td>
<td> 109-005-003</td>
<td>&nbsp;</td>
<tr>
<td>KCl</td>
<td>&nbsp;</td>
<td>MP Biologicals</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<tr>
<td>LiCl</td>
<td>&nbsp;</td>
<td>Sigma</td>
<td>L4408</td>
<td>&nbsp;</td>
<tr>
<td>MgCl2</td>
<td>&nbsp;</td>
<td>Sigma</td>
<td>M8266</td>
<td>&nbsp;</td>
<tr>
<td>Sodium Acetate</td>
<td>&nbsp;</td>
<td>Fisher</td>
<td>BP333-500</td>
<td>&nbsp;</td>
<tr>
<td>Deoxycholic Acid Sodium Salt</td>
<td>&nbsp;</td>
<td>Fisher</td>
<td>BP349-100</td>
<td>&nbsp;</td>
<tr>
<td>NaCl</td>
<td>&nbsp;</td>
<td>Fisher</td>
<td>7647-14-5</td>
<td>&nbsp;</td>
<tr>
<td>NP40</td>
<td>&nbsp;</td>
<td>US Biological</td>
<td>N3500</td>
<td>&nbsp;</td>
<tr>
<td>Anti-Histone H3, CT, pan</td>
<td>&nbsp;</td>
<td>Millipore</td>
<td>07-690</td>
<td>&nbsp;</td>
<tr>
<td>Phenol/chloroform/isoamyl</td>
<td>&nbsp;</td>
<td>Fisher</td>
<td>108-95-2</td>
<td>&nbsp;</td>
<tr>
<td>Phosphate Buffered Saline</td>
<td>&nbsp;</td>
<td>Fisher</td>
<td>7647-14-5</td>
<td>&nbsp;</td>
<tr>
<td>PMSF</td>
<td>&nbsp;</td>
<td>EMD</td>
<td>50-230-0316</td>
<td>&nbsp;</td>
<tr>
<td>Proteinase K</td>
<td>&nbsp;</td>
<td>5-Prime</td>
<td>2500140</td>
<td>&nbsp;</td>
<tr>
<td>RNAse A</td>
<td>&nbsp;</td>
<td>5-Prime</td>
<td>2500130</td>
<td>&nbsp;</td>
<tr>
<td>Salmon Sperm DNA/Protein A Agarose</td>
<td>&nbsp;</td>
<td>Millipore</td>
<td>16-157</td>
<td>&nbsp;</td>
<tr>
<td>Salmon Sperm DNA/Protein G Agaorse</td>
<td>&nbsp;</td>
<td>Millipore</td>
<td>16-201</td>
<td>&nbsp;</td>
<tr>
<td>SDS</td>
<td>&nbsp;</td>
<td>Fisher</td>
<td>BP166-500</td>
<td>&nbsp;</td>
<tr>
<td>Tris-Cl</td>
<td>&nbsp;</td>
<td>Sigma</td>
<td>T5941</td>
<td>&nbsp;</td>
<tr>
<td>Triton X-100</td>
<td>&nbsp;</td>
<td>Acros</td>
<td>327372500</td>
<td>&nbsp;</td>
<tr>
<td>Anti-K36me3</td>
<td>&nbsp;</td>
<td>Abcam</td>
<td>ab9050</td>
<td>&nbsp;</td>
<tr>
<td>Anti-STAT1</td>
<td>&nbsp;</td>
<td>Santa Cruz</td>
<td>sc-345X</td>
<td>&nbsp;</td>
<tr>
<td>Anti-RNA Polymerase II</td>
<td>&nbsp;</td>
<td>Santa Cruz</td>
<td>sc-899</td>
<td>&nbsp;</td>		</tbody>
		</table>
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chromatin immunoprecipitation (chip) to assay dynamic histone modification in activated gene expression in human cells

In Reaktion auf eine Vielzahl von extrazellulären Liganden, die STAT (Signal Transducer und Aktivator der Transkription) Transkriptionsfaktoren werden schnell von ihren latenten Zustand im Zytoplasma an Zelloberflächenrezeptoren, wo sie durch Phosphorylierung an einem Tyrosin-Rest 1 aktiviert werden rekrutiert. Dann dimerisieren und in den Zellkern transloziert, um die Transkription von Zielgenen fahren, die sich auf Wachstum, Differenzierung, Homöostase und der Immunantwort. Es überrascht nicht, angesichts ihrer weit verbreiteten Einbindung in normale Zelle Prozesse trägt Dysregulation der STAT-Funktion, um menschliche Krankheiten, insbesondere Krebs 2 und autoimmune Krankheiten 3. Es ist bekannt, dass die Transkription von Änderungen ist es, die Chromatin-Template 4,5 geregelt. Diese Veränderungen umfassen die Aktivitäten von ATP-abhängigen Komplexen, sowie kovalenten Histon-Modifikationen und DNA-Methylierung 6. Da STAT Aktivierung der Genexpression ist schnell und transient, bedarf es spezifische Mechanismen für die Modulation der Chromatin-Template an STAT-abhängigen Gen-Loci. So definieren Sie diese Mechanismen charakterisieren wir die Histon-Modifikationen und die enzymatischen Aktivitäten, die sie an Genorte, die STAT-Signalisierung reagieren zu generieren. Dieses Protokoll beschreibt Chromatinimmunpräzipitation, eine Methode, die wertvoll für das Studium der STAT-Signalisierung an Chromatin in aktiviert die Genexpression.

Watch this Scientific Journal Video about Chromatin Immunoprecipitation ChIP to Assay Dynamic Histone Modification in Activated Gene Expression in Human Cells at JoVE.com

Chromatin Immunoprecipitation ChIP to Assay Dynamic Histone Modification in Activated Gene Expression in Human Cells

Dieses Protokoll beschreibt, wie Chromatin-Immunopräzipitation (ChIP) verwendet wird, um den dynamischen Veränderungen der Chromatin-Vorlage, die Transkription von einem Signaltransduktionsweg induziert regulieren zu studieren.

Chromatin Immunopräzipitation (ChIP) zur Assay Dynamische Histonmodifikationen in Activated Gene Expression in menschlichen Zellen

In response to a variety of extracellular ligands, the STAT (signal transducer and activator of transcription) transcription factors are rapidly recruited ...

chromatin-immunoprecipitation-chip-to-assay-dynamic-histone

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JoVE Journal

Biology

Chromatin Immunoprecipitation (ChIP) to Assay Dynamic Histone Modification in Activated Gene Expression in Human Cells

28.5K Aufrufe.  University of Virginia. Dieses Protokoll beschreibt, wie Chromatin-Immunopräzipitation (ChIP) verwendet wird, um den dynamischen Veränderungen der Chromatin-Vorlage, die Transkription von einem Signaltransduktionsweg induziert regulieren zu studieren.

Serie: Chromatin Immunoprecipitation ChIP to Assay Dynamic Histone Modification in Activated Gene Expression in Human Cells

Chromatin Immunoprecipitation from Human Embryonic Stem Cells

The functional and structural complexity of the myriad of cells in metazoan organisms arises from a small number of stem cells. Stem cells are characterized by two fundamental properties: self-renewal and multipotency that allows a stem cell to differentiate into virtually any cell type 1. The progression stem cell to differentiated cell is characterized by loss of multipotency, structural and morphological changes and the hierarchic activity of transcription factors and signaling molecules, whose activities establish and maintain cell-type specific gene expression patterns. At the molecular level, cell differentiation involves dynamic changes of the structure and composition of chromatin and the detection of those dynamic changes can provide valuable insights into the functional features of stem cells and the cell differentiation process 2,3. Chromatin is a highly compacted DNA-protein complex that forms when cells package chromosomal DNA with proteins, mainly histones 4. Stemcellness and cell differentiation has been correlated with the presence of specific arrays of regulatory proteins such as epigenetic factors, histone variants, and transcription factors 2,3,5.
 Chromatin immunoprecipitation (ChIP) provides a valuable method to monitor the presence of RNA, proteins, and protein modifications in chromatin 6,7. The comparison of chromatin from different cell types can elucidate dynamic changes in protein-chromatin associations that occur during cell differentiation.
Chromatin immunoprecipitation involves the purification of in vivo cross-linked chromatin. The isolated chromatin is reduced to smaller fragments by enzymatic digestion or mechanical force. Chromatin fragments are precipitated using specific antibodies to target proteins or protein and DNA modifications. The precipitated DNA or RNA is purified and used as a template for PCR or DNA microarray based assays. Prerequisites for a successful ChIP are high quality antibodies to the desired antigen and the availability of chromatin from control cells that do not express the target molecule. ChIP can correlate the presence of proteins, protein and RNA modifications, and RNA with specific target DNA, and depending on the choice of outread tool, detects the association of target molecules at specific target genes or in the context of an entire genome. The comparison of the distribution of proteins in the chromatin of differentiating cells can elucidate the dynamic changes of chromatin composition that coincide with the progression of cells along a cell lineage.

The differentiation of ESC coincides with cell-type specific changes in the structure and composition of chromatin. The detection of those changes provides valuable insights into the mechanisms that define stemcellness and cell differentiation. Chromatin immunoprecipitation (ChIP) represents a valuable method to dissect the molecular mechanisms underlying stem cell differentiation.

Chromatin Immunopräzipitation von humanen embryonalen Stammzellen

The functional and structural complexity of the myriad of cells in metazoan organisms arises from a small number of stem cells. Stem cells are ...

Forschung

Biologie

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

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

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

Mit dem Gene Pulser MXcell Elektroporation System zur Primary Cells mit hohem Wirkungsgrad zu transfizieren

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

Robotics and Dynamic Image Analysis for Studies of Gene Expression in Plant Tissues

Gene expression in plant tissues is typically studied by destructive extraction of compounds from plant tissues for in vitro analyses. The methods presented here utilize the green fluorescent protein (gfp) gene for continual monitoring of gene expression in the same pieces of tissues, over time. The gfp gene was placed under regulatory control of different promoters and introduced into lima bean cotyledonary tissues via particle bombardment. Cotyledons were then placed on a robotic image collection system, which consisted of a fluorescence dissecting microscope with a digital camera and a 2-dimensional robotics platform custom-designed to allow secure attachment of culture dishes. Images were collected from cotyledonary tissues every hour for 100 hours to generate expression profiles for each promoter. Each collected series of 100 images was first subjected to manual image alignment using ImageReady to make certain that GFP-expressing foci were consistently retained within selected fields of analysis. Specific regions of the series measuring 300 x 400 pixels, were then selected for further analysis to provide GFP Intensity measurements using ImageJ software. Batch images were separated into the red, green and blue channels and GFP-expressing areas were identified using the threshold feature of ImageJ. After subtracting the background fluorescence (subtraction of gray values of non-expressing pixels from every pixel) in the respective red and green channels, GFP intensity was calculated by multiplying the mean grayscale value per pixel by the total number of GFP-expressing pixels in each channel, and then adding those values for both the red and green channels. GFP Intensity values were collected for all 100 time points to yield expression profiles. Variations in GFP expression profiles resulted from differences in factors such as promoter strength, presence of a silencing suppressor, or nature of the promoter. In addition to quantification of GFP intensity, the image series were also used to generate time-lapse animations using ImageReady. Time-lapse animations revealed that the clear majority of cells displayed a relatively rapid increase in GFP expression, followed by a slow decline. Some cells occasionally displayed a sudden loss of fluorescence, which may be associated with rapid cell death. Apparent transport of GFP across the membrane and cell wall to adjacent cells was also observed. Time lapse animations provided additional information that could not otherwise be obtained using GFP Intensity profiles or single time point image collections.

We report a method for introduction, tracking and quantitative analysis of GFP expression in plant cells. This method utilizes a custom-designed robotics system for semi-continuous image collection from large numbers of samples, over time. We also demonstrate the use of ImageJ and ImageReady for analysis of image series.

Robotik und Dynamic Image Analysis für Studies of Gene Expression in pflanzlichen Geweben

Gene expression in plant tissues is typically studied by destructive extraction of compounds from plant tissues for in vitro analyses. The methods ...

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

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

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

Verwendung eines automatisierten Cell Counter zu Genexpressionsstudien Simplify: siRNA Knockdown von IL-4 abhängige Genexpression in Namalwalzellen

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

An Allele-specific Gene Expression Assay to Test the Functional Basis of Genetic Associations

The number of significant genetic associations with common complex traits is constantly increasing. However, most of these associations have not been understood at molecular level. One of the mechanisms mediating the effect of DNA variants on phenotypes is gene expression, which has been shown to be particularly relevant for complex traits1.
This method tests in a cellular context the effect of specific DNA sequences on gene expression. The principle is to measure the relative abundance of transcripts arising from the two alleles of a gene, analysing cells which carry one copy of the DNA sequences associated with disease (the risk variants)2,3. Therefore, the cells used for this method should meet two fundamental genotypic requirements: they have to be heterozygous both for DNA risk variants and for DNA markers, typically coding polymorphisms, which can distinguish transcripts based on their chromosomal origin (Figure 1). DNA risk variants and DNA markers do not need to have the same allele frequency but the phase (haplotypic) relationship of the genetic markers needs to be understood. It is also important to choose cell types which express the gene of interest. This protocol refers specifically to the procedure adopted to extract nucleic acids from fibroblasts but the method is equally applicable to other cells types including primary cells.
DNA and RNA are extracted from the selected cell lines and cDNA is generated. DNA and cDNA are analysed with a primer extension assay, designed to target the coding DNA markers4. The primer extension assay is carried out using the MassARRAY (Sequenom)5 platform according to the manufacturer's specifications. Primer extension products are then analysed by matrix-assisted laser desorption/ionization time of-flight mass spectrometry (MALDI-TOF/MS). Because the selected markers are heterozygous they will generate two peaks on the MS profiles. The area of each peak is proportional to the transcript abundance and can be measured with a function of the MassARRAY Typer software to generate an allelic ratio (allele 1: allele 2) calculation. The allelic ratio obtained for cDNA is normalized using that measured from genomic DNA, where the allelic ratio is expected to be 1:1 to correct for technical artifacts. Markers with a normalised allelic ratio significantly different to 1 indicate that the amount of transcript generated from the two chromosomes in the same cell is different, suggesting that the DNA variants associated with the phenotype have an effect on gene expression. Experimental controls should be used to confirm the results.

Genetic associations often remain unexplained at a functional level. This method aims to assess the effect of phenotype-associated genetic markers on gene expression by analyzing cells heterozygous for transcribed SNPs. The technology allows accurate measurement by MALDI-TOF mass spectrometry to quantify allele-specific primer extension products.

Ein Allel-spezifische Gene Expression Assay zur Funktionsanalyse Grundlage genetischer Verbände testen

The number of significant genetic associations with common complex traits is constantly increasing. However, most of these associations have not been ...

Clonogenic Assay: Adherent Cells

The clonogenic (or colony forming) assay has been established for more than 50 years; the original paper describing the technique was published in 19561. Apart from documenting the method, the initial landmark study generated the first radiation-dose response curve for X-ray irradiated mammalian (HeLa) cells in culture1. Basically, the clonogenic assay enables an assessment of the differences in reproductive viability (capacity of cells to produce progeny; i.e. a single cell to form a colony of 50 or more cells) between control untreated cells and cells that have undergone various treatments such as exposure to ionising radiation, various chemical compounds (e.g. cytotoxic agents) or in other cases genetic manipulation. The assay has become the most widely accepted technique in radiation biology and has been widely used for evaluating the radiation sensitivity of different cell lines. Further, the clonogenic assay is commonly used for monitoring the efficacy of radiation modifying compounds and for determining the effects of cytotoxic agents and other anti-cancer therapeutics on colony forming ability, in different cell lines. A typical clonogenic survival experiment using adherent cells lines involves three distinct components, 1) treatment of the cell monolayer in tissue culture flasks, 2) preparation of single cell suspensions and plating an appropriate number of cells in petri dishes and 3) fixing and staining colonies following a relevant incubation period, which could range from 1-3 weeks, depending on the cell line. Here we demonstrate the general procedure for performing the clonogenic assay with adherent cell lines with the use of an immortalized human keratinocyte cell line (FEP-1811)2. Also, our aims are to describe common features of clonogenic assays including calculation of the plating efficiency and survival fractions after exposure of cells to radiation, and to exemplify modification of radiation-response with the use of a natural antioxidant formulation.

The applicability of the clonogenic assay for evaluating reproductive viability has been established for more than 50 years. Here we demonstrate the general procedure for performing the clonogenic assay with adherent cells.

Klonogene Test: adhärenter Zellen

The clonogenic (or colony forming) assay has been established for more than 50 years; the original paper describing the technique was published in 19561. ...

Chromatin Immunoprecipitation Assay for Tissue-specific Genes using Early-stage Mouse Embryos

Chromatin immunoprecipitation (ChIP) is a powerful tool to identify protein:chromatin interactions that occur in the context of living cells 1-3. This technique has been widely exploited in tissue culture cells, and to a lesser extent, in primary tissue. The application of ChIP to rodent embryonic tissue, especially at early times of development, is complicated by the limited amount of tissue and the heterogeneity of cell and tissue types in the embryo. Here we present a method to perform ChIP using a dissociated embryonic day 8.5 (E8.5) embryo. Sheared chromatin from a single E8.5 embryo can be divided into up to five aliquots, which allows the investigator sufficient material for controls and for investigation of specific protein:chromatin interactions.
We have utilized this technique to begin to document protein:chromatin interactions during the specification of tissue-specific gene expression programs. The heterogeneity of cell types in an embryo necessarily restricts the application of this technique because the result is the detection of protein:chromatin interactions without distinguishing whether the interactions occur in all, a subset of, or a single cell type(s). However, examination of tissue-specific genes during or following the onset of tissue-specific gene expression is feasible for two reasons. First, immunoprecipitation of tissue specific factors necessarily isolates chromatin from the cell type where the factor is expressed. Second, immunoprecipitation of coactivators and histones containing post-translational modifications that are associated with gene activation should only be found at genes and gene regulatory sequences in the cell type where the gene is being or has been activated. The technique should be applicable to the study of most tissue-specific gene activation events.
In the example described below, we utilized E8.5 and E9.5 mouse embryos to examine factor binding at a skeletal muscle specific gene promoter. Somites, which are the precursor tissues from which the skeletal muscles of the trunk and limbs will form, are present at E8.5-9.54,5. Myogenin is a regulatory factor required for skeletal muscle differentiation 6-9. The data demonstrate that myogenin is associated with its own promoter in E8.5 and E9.5 embryos. Because myogenin is only expressed in somites at this stage of development 6,10, the data indicate that myogenin interactions with its own promoter have already occurred in skeletal muscle precursor cells in E8.5 embryos.

We demonstrate a chromatin immunoprecipitation (ChIP) method to identify factor interactions at tissue-specific genes during or after the onset of tissue-specific gene expression in mouse embryonic tissue. This protocol should be widely applicable for the study of tissue-specific gene activation as it occurs during normal embryonic development.

Chromatin Immunopräzipitation-Assay für Tissue-spezifische Gene mit Frühzeitige muriner Embryonen

Chromatin immunoprecipitation (ChIP) is a powerful tool to identify protein:chromatin interactions that occur in the context of living cells 1-3. This ...

In vitro Reconstitution of the Active T. castaneum Telomerase

Efforts to isolate the catalytic subunit of telomerase, TERT, in sufficient quantities for structural studies, have been met with limited success for more than a decade. Here, we present methods for the isolation of the recombinant Tribolium castaneum TERT (TcTERT) and the reconstitution of the active T. castaneum telomerase ribonucleoprotein (RNP) complex in vitro.
Telomerase is a specialized reverse transcriptase1 that adds short DNA repeats, called telomeres, to the 3' end of linear chromosomes2 that serve to protect them from end-to-end fusion and degradation. Following DNA replication, a short segment is lost at the end of the chromosome3 and without telomerase, cells continue dividing until eventually reaching their Hayflick Limit4. Additionally, telomerase is dormant in most somatic cells5 in adults, but is active in cancer cells6 where it promotes cell immortality7.
The minimal telomerase enzyme consists of two core components: the protein subunit (TERT), which comprises the catalytic subunit of the enzyme and an integral RNA component (TER), which contains the template TERT uses to synthesize telomeres8,9. Prior to 2008, only structures for individual telomerase domains had been solved10,11. A major breakthrough in this field came from the determination of the crystal structure of the active12, catalytic subunit of T. castaneum telomerase, TcTERT1.
Here, we present methods for producing large quantities of the active, soluble TcTERT for structural and biochemical studies, and the reconstitution of the telomerase RNP complex in vitro for telomerase activity assays. An overview of the experimental methods used is shown in Figure 1.

In vitro Reconstitution of the Active T. castaneum Telomerase

Efforts to isolate the catalytic subunit of telomerase, TERT, in sufficient quantities for structural studies, have been met with limited success for more than a decade. Here, we present methods for the isolation of the recombinant Tribolium castaneum TERT (TcTERT) and the reconstitution of the active T. castaneum telomerase ribonucleoprotein (RNP) complex in vitro.

In vitro Rekonstitution der Active T. castaneum Telomerase

Efforts to isolate the catalytic subunit of telomerase, TERT, in sufficient quantities for structural studies, have been met with limited success for more ...

Chromatin Immunoprecipitation (ChIP) using Drosophila tissue

Epigenetics remains a rapidly developing field that studies how the chromatin state contributes to differential gene expression in distinct cell types at different developmental stages. Epigenetic regulation contributes to a broad spectrum of biological processes, including cellular differentiation during embryonic development and homeostasis in adulthood. A critical strategy in epigenetic studies is to examine how various histone modifications and chromatin factors regulate gene expression. To address this, Chromatin Immunoprecipitation (ChIP) is used widely to obtain a snapshot of the association of particular factors with DNA in the cells of interest.
ChIP technique commonly uses cultured cells as starting material, which can be obtained in abundance and homogeneity to generate reproducible data. However, there are several caveats: First, the environment to grow cells in Petri dish is different from that in vivo, thus may not reflect the endogenous chromatin state of cells in a living organism. Second, not all types of cells can be cultured ex vivo. There are only a limited number of cell lines, from which people can obtain enough material for ChIP assay.
Here we describe a method to do ChIP experiment using Drosophila tissues. The starting material is dissected tissue from a living animal, thus can accurately reflect the endogenous chromatin state. The adaptability of this method with many different types of tissue will allow researchers to address a lot more biologically relevant questions regarding epigenetic regulation in vivo1, 2. Combining this method with high-throughput sequencing (ChIP-seq) will further allow researchers to obtain an epigenomic landscape.

Chromatin Immunoprecipitation ChIP using Drosophila tissue

Recently high-throughput sequencing technology has greatly increased sensitivity of Chromatin Immunoprecipitation (ChIP) experiment and prompted its application using purified cells or dissected tissue. Here we delineate a method to use ChIP technique with Drosophila tissue, which can address the endogenous chromatin state in a well-characterized biological system.

Chromatin Immunopräzipitation (ChIP) mit Drosophila Gewebe

Epigenetics remains a rapidly developing field that studies how the chromatin state contributes to differential gene expression in distinct cell types at ...

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.

Mit SECM Arrest Sequenz als Werkzeug zum Ribosom gebunden Polypeptide isolieren

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