Name: high-resolution mapping of protein-dna interactions in mouse stem cell-derived neurons using chromatin immunoprecipitation-exonuclease (chip-exo)
Uploaded: 2020-08-14T16:00:00
Description: Watch this Scientific Journal Video about High-Resolution Mapping of Protein-DNA Interactions in Mouse Stem Cell-Derived Neurons using Chromatin Immunoprecipitation-Exonuclease ChIP-Exo at JoVE.com

Vi takker medlemmet av Rhee-laboratoriet for å dele upubliserte data og verdifulle diskusjoner. Dette arbeidet ble støttet av Natural Sciences and Engineering Research Council of Canada (NSERC) stipend RGPIN-2018-06404 (H.R.).

MERK: Autoklavet destillert og deionisert vann (ddH2O) anbefales for å lage buffere og reaksjonsmasterblandinger. Avsnitt 1−4 beskriver cellelys og sonikering, avsnitt 5-7 beskriver kromatinimmunoprecipitation (ChIP), avsnitt 8-11 beskriver enzymatiske reaksjoner på perler, avsnitt 12 og 13 beskriver ChIP-renselse og DNA-rensing, og avsnitt 14−19 beskriver bibliotekforberedelse.
1. Høsting og krysskobling av celler
<ol><li>Etter differensiering av mus ES-ce...

<ol>
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S., 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=Expression+of+Terminal+Effector+Genes+in+Mammalian+Neurons+Is+Maintained+by+a+Dynamic+Relay+of+Transient+Enhancers.">Expression of Terminal Effector Genes in Mammalian Neurons Is Maintained by a Dynamic Relay of Transient Enhancers.</a> Neuron. 92 (6), 1252-1265 (2016).</li><li>Pugh, B. F., Venters, B. 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J., 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=c-Myc+Antagonises+the+Transcriptional+Activity+of+the+Androgen+Receptor+in+Prostate+Cancer+Affecting+Key+Gene+Networks.">c-Myc Antagonises the Transcriptional Activity of the Androgen Receptor in Prostate Cancer Affecting Key Gene Networks.</a> Ebiomedicine. 18, 83-93 (2017).</li><li>McHaourab, Z. F., Perreault, A. A., Venters, B. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=ChIP-seq+and+ChIP-exo+profiling+of+Pol+II,+H2A.Z,+and+H3K4me3+in+human+K562+cells.">ChIP-seq and ChIP-exo profiling of Pol II, H2A.Z, and H3K4me3 in human K562 cells.</a> Scientific Data. 5, 180030 (2018).</li><li>Perreault, A. A., Sprunger, D. M., Venters, B. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Epigenetic+and+transcriptional+profiling+of+triple+negative+breast+cancer.">Epigenetic and transcriptional profiling of triple negative breast cancer.</a> Scientific Data. 6, 190033 (2019).</li><li>Rossi, M. J., Lai, W. K. M., Pugh, B. F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Simplified+ChIP-exo+assays.">Simplified ChIP-exo assays.</a> Nature Communications. 9 (1), 2842 (2018).</li><li>Perreault, A. A., Venters, B. 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(130), (2017).</li><li>Terranova, C., 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=An+Integrated+Platform+for+Genome-wide+Mapping+of+Chromatin+States+Using+High-throughput+ChIP-sequencing+in+Tumor+Tissues.">An Integrated Platform for Genome-wide Mapping of Chromatin States Using High-throughput ChIP-sequencing in Tumor Tissues.</a> Journal of Visualized Experiments. (134), (2018).</li><li>Pchelintsev, N. A., Adams, P. D., Nelson, D. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Critical+Parameters+for+Efficient+Sonication+and+Improved+Chromatin+Immunoprecipitation+of+High+Molecular+Weight+Proteins.">Critical Parameters for Efficient Sonication and Improved Chromatin Immunoprecipitation of High Molecular Weight Proteins.</a> PLos One. 11 (1), (2016).</li><li>Yamada, N., Lai, W. K. 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I denne protokollen brukes ChIP etterfulgt av exonuclease fordøyelse til å skaffe DNA-biblioteker for identifisering av protein-DNA-interaksjoner i pattedyrceller ved ultrahøy kartleggingsoppløsning. Mange variabler bidrar til kvaliteten på ChIP-exo-eksperimentet. Kritiske eksperimentelle parametere inkluderer kvaliteten på antistoffer, optimalisering av sonikering, og antall LM-PCR sykluser. Disse kritiske eksperimentelle parametrene er også det som kan begrense ChIP-exo eksperimenter og vil bli diskutert nedenfo...

Plasseringen av protein-DNA interaksjoner gir innsikt i mekanismene for genregulering. Kromatin immunoprecipitation kombinert med høy gjennomstrømning sekvensering (ChIP-seq) har blitt brukt i et tiår for å undersøke genom-wide protein-DNA interaksjoner i levendeceller 1,2. ChIP-seq-metoden er imidlertid begrenset av heterogenitet i DNA-fragmentering og ubundet DNA-kontaminering som fører til lav kartløsning, falske positiver, tapte anrop og ikke-spesifikt bakgrunnssignal. Kombinasjonen av ChIP med exonuclease fordøyelse (ChIP-exo) forbedrer chip-seq-metoden ved å trimme ChIP DNA til protein-DNA crosslinking poeng, og gir nær base-pair oppløsning og et lavt bakgrunnssignal3,4,5. Den sterkt forbedrede kartleggingsoppløsningen og lav bakgrunn fra ChIP-exo gjør det mulig å bestemme nøyaktige og omfattende protein-DNA-bindende steder på tvers av genomet. ChIP-exo er i stand til å avsløre funksjonelt distinkte DNA-bindende motiver, samarbeidende interaksjoner mellom transkripsjonsfaktorer (TF) og flere protein-DNA krysskoblingssteder på et bestemt genomisk bindende sted, ikke påviselig ved andre genomiske kartmetoder3,4,6,7.
ChIP-exo ble opprinnelig brukt i spirende gjær for å undersøke sekvensspesifikk DNA-binding av TFs, for å studere den nøyaktige organiseringen av transkripsjonskomplekset før initieringskomplekset, og subnukleosomal struktur av individuelle histoner overgenomet 4,8,9. Siden introduksjonen i 20114har ChIP-exo blitt brukt i mange andre organismer, inkludert bakterier, mus og menneskeligeceller 7,10,11,12,13,14,15,16,17. I 2016 brukte Rhee et al.14 ChIP-exo i pattedyrnevroner for første gang for å forstå hvordan nevronalt genuttrykk ble opprettholdt etter nedreguleringen av programmering TF Lhx3, som danner et heterodimerkompleks med en annen programmering TF Isl1. Denne studien viste at i fravær av Lhx3 rekrutteres Isl1 til nye nevronale enhancers bundet av Onecut1 TF for å opprettholde genuttrykk av nevronale effektorgener. I denne studien avslørte ChIP-exo hvordan flere TFs dynamisk gjenkjenner celletype og cellestadsspesifikke DNA-regulatoriske elementer på en kombinatorisk måte ved nærkjerneotidkartløsning. Andre studier brukte også ChIP-exo-metoden for å forstå samspillet mellom proteiner og DNA i andre pattedyrcellelinjer. Han et al.7 brukte ChIP-exo til å undersøke genomet-wide organisering av GATA1 og TAL1 TFs i mus erythroid celler ved hjelp av ChIP-exo. Denne studien fant at TAL1 er direkte rekruttert til DNA i stedet for indirekte gjennom protein-protein interaksjoner med GATA1 gjennom erythroid differensiering. Nyere studier brukte også ChIP-exo til å profilere genomomfattende bindingssteder av CTCF, RNA Polymerase II og histonemerker for å studere epigenomiske og transkripsjonelle mekanismer i menneskeligecellelinjer 18,19.
Det finnes flere versjoner av ChIP-exo-protokollen tilgjengelig3,5,20. Disse ChIP-exo-protokollene er imidlertid vanskelige å følge for undersøkelser som ikke er kjent med neste generasjons sekvenseringsbibliotekforberedelse. En utmerket versjon av ChIP-exo-protokollen ble publisert med enkle å følge instruksjoner og en video21, men inneholdt mange enzymatiske trinn som krever en betydelig mengde tid å fullføre. Her rapporterer vi en ny versjon av ChIP-exo-protokollen som inneholder reduserte enzymatiske trinn og inkubasjonstider, og forklaringer for hvert enzymatisketrinn 21. Sluttreparasjon og dA-tailing reaksjoner kombineres i et enkelt trinn ved hjelp av end prep enzymet. Inkubasjonstidene for indeks- og universaladapter ligation trinn reduseres fra 2 t til 15 min ved hjelp av en ligation enhancer. Kinasereaksjonen etter indeksadapterens ligationtrinn som er beskrevet i den forrige ChIP-exo-protokollen, fjernes. I stedet tilsettes en fosfatgruppe under oligo DNA-syntese til en av de 5' endene av indeksadapteren (tabell 1), som vil bli brukt til lambda exonuclease fordøyelsestrinn. Mens den forrige ChIP-exo-protokollen brukte RecJf exonuclease fordøyelsen for å eliminere single-stranded DNA forurensninger, dette fordøyelsestrinnet fjernes her fordi det ikke er avgjørende for kvaliteten på ChIP-exo biblioteket. I tillegg, for å rense omvendt krysskoblet DNA etter ChIP-elitasjon, brukes en magnetisk perler rensemetode i stedet for fenol:kloroform:isoamylalkohol (PCIA) ekstraksjonsmetode. Dette reduserer inkubasjonstiden for DNA-ekstraksjon. Viktigere, det fjerner flertallet av adapter dimers dannet under indeks adapter ligation, noe som kan påvirke effektiviteten av ligation-mediert PCR.
ChIP-exo-protokollen som presenteres her er optimalisert for påvisning av presise protein-DNA-interaksjoner i pattedyrnevroner differensiert fra mus embryonale stamceller (ES). Kort, høstet og krysskoblet neuronal celler er lysed, slik at kromatin å bli utsatt for sonikering, deretter sonikert slik at riktig størrelse DNA fragmenter oppnås (Figur 1). Antistoffbelagte perler brukes deretter til selektivt immunprecipitate fragmentert, oppløselig kromatin til protein av interesse. Mens immunforeskrivet DNA er fortsatt på perlene, end-reparasjon, ligation av sekvensering adaptere, fill-in reaksjon og 5 ' til 3 ' lambda exonuclease fordøyelsen trinn utføres. Det eksonukleære fordøyelsestrinnet er det som gir ChIP-exo sin ultrahøy oppløsning og høyt signal-til-støy-forhold. Lambda exonuclease trimmer immunprecipitated DNA noen base-par (bp) fra krysskoblingsstedet, og dermed forårsaker forurensende DNA å bli degradert. Det eksonukleære ChIP DNA er eluted fra antistoffbelagte perler, protein-DNA krysskoblinger reverseres, og proteiner brytes ned. DNA ekstraheres og denatureres til en strandet ChIP DNA, etterfulgt av primer annealing og forlengelse for å lage dobbelttrådet DNA (dsDNA). Deretter utføres ligation av en universell adapter til de eksonuklelebehandlede endene. Det resulterende DNA renses, deretter PCR forsterket, gel renset, og utsatt for neste generasjons sekvensering.
ChIP-exo-protokollen er lengre enn ChIP-seq-protokollen, men er ikke veldig teknisk utfordrende. Enhver vellykket immunprecipitated ChIP DNA kan bli utsatt for ChIP-exo, med flere ekstra enzymatiske trinn. De bemerkelsesverdige fordelene med ChIP-exo, for eksempel ultrahøy kartleggingsoppløsning, et redusert bakgrunnssignal og reduserte falske positive og negativer, angående genomiske bindingssteder, oppveier tidskostnadene.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr >
			<td >Agarose, UltraPure</td>
			<td >Invitrogen</td>
			<td >16500</td>
			<td >Checking Sonication (Section 4.3.6) and Gel Purification of LM-PCR Amplified DNA (Section 19.1)</td>
		</tr>
		<tr >
			<td >Albumin, Bovine Serum (BSA), Protease Free, Heat Shock Isolation, Min. 98%</td>
			<td >BioShop</td>
			<td >ALB003</td>
			<td >Blocking Solution</td>
		</tr>
		<tr >
			<td >Antibody against Isl1</td>
			<td >DSHB</td>
			<td >39.3F7</td>
			<td >Antibody incuation with beads (Section 5.6)</td>
		</tr>
		<tr >
			<td >Bioruptor Pico&#160;</td>
			<td >Diagenode</td>
			<td >B01060010</td>
			<td >Sonicating Chromatin (Section 3.3)</td>
		</tr>
		<tr >
			<td >Bovine serum albumin (BSA), Molecular Biology Grade</td>
			<td >New England BioLabs</td>
			<td >B9000S</td>
			<td >Fill-in Reaction on Beads (Section 10.2) and Denaturing, Primer Annealing and Primer Extension (Section 14.2)</td>
		</tr>
		<tr >
			<td >Centrifuge 5424 R</td>
			<td >Eppendorf</td>
			<td >5404000138</td>
			<td >Sonicating Chromatin (Section 3.5), Checking Sonication (Section 4.3.1, 4.3.3 and 4.3.4)</td>
		</tr>
		<tr >
			<td >Centrifuge 5804 R</td>
			<td >Eppendorf</td>
			<td >22623508</td>
			<td >Harvest, cross-linking and freezing cells (Section 1.3), Cell lysis (Section 2.2 and 2.3), Sonicating Chromatin (Section 3.1)</td>
		</tr>
		<tr >
			<td >cOmplete, Mini, EDTA-free Protease Inhibitor Cocktail</td>
			<td >Roche</td>
			<td >4693159001</td>
			<td >Added to all buffers, except Proteinase K buffer and ChIP Elution buffer</td>
		</tr>
		<tr >
			<td >dATP Solution</td>
			<td >New England BioLabs</td>
			<td >N0440S</td>
			<td >dA-Tailing Reaction (Section 15.1)</td>
		</tr>
		<tr >
			<td >Deoxycholic Acid Sodium Salt</td>
			<td >fisher scientific</td>
			<td >BP349</td>
			<td >Lysis Buffer 3, High Salt Wash Buffer and LiCl Wash Buffer</td>
		</tr>
		<tr >
			<td >dNTP Mix, Molecular Biology Grade</td>
			<td >Thermo Scientific</td>
			<td >R0192</td>
			<td >Fill-in Reaction on Beads (Section 10.2) and Denaturing, Primer Annealing and Primer Extension (Section 14.2)</td>
		</tr>
		<tr >
			<td >DreamTaq Green PCR Master Mix, 2x&#160;</td>
			<td >Thermo Scientific</td>
			<td >K1081</td>
			<td >Ligation-Mediated PCR (Section 18.1)</td>
		</tr>
		<tr >
			<td >EDTA, 0.5 M, Sterile Solution, pH 8.0</td>
			<td >BioShop</td>
			<td >EDT111</td>
			<td >Lysis Buffer 1-3, Checking Sonication (Section 4.1), High Salt Wash Buffer, LiCl Wash Buffer and ChIP Elution Buffer</td>
		</tr>
		<tr >
			<td >Ethyl Alcohol Anhydrous, 100%</td>
			<td >Commercial alcohols</td>
			<td >P006EAAN</td>
			<td >Checking Sonication (Section 4.3.3)</td>
		</tr>
		<tr >
			<td >Formaldehyde, 36.5-38%, contains 10-15% methanol</td>
			<td >Sigma</td>
			<td >F8775</td>
			<td >Harvest, cross-linking and freezing cells (Section 1.1)</td>
		</tr>
		<tr >
			<td >Glycerol, Reagent Grade, min 99.5%</td>
			<td >BioShop</td>
			<td >GLY002</td>
			<td >Lysis Buffer 1</td>
		</tr>
		<tr >
			<td >Glycine, Biotechnology Grade, min. 99%</td>
			<td >BioShop</td>
			<td >GLN001</td>
			<td >Harvest, cross-linking and freezing cells (Section 1.2)</td>
		</tr>
		<tr >
			<td >Glycogen, RNA Grade</td>
			<td >Thermo Scientific</td>
			<td >R0551</td>
			<td >Checking Sonication (Section 4.3.3)</td>
		</tr>
		<tr >
			<td >HEPES, 1 M Sterile-filtered Solution, pH 7.3&#160;</td>
			<td >BioShop</td>
			<td >HEP003</td>
			<td >Lysis Buffer 1, High Salt Wash Buffer</td>
		</tr>
		<tr >
			<td >Klenow Fragment (3-&#62;5 exo-)</td>
			<td >New England BioLabs</td>
			<td >M0212S</td>
			<td >dA-Tailing Reaction (Section 15.1)</td>
		</tr>
		<tr >
			<td >Lambda exonuclease</td>
			<td >New England BioLabs</td>
			<td >M0262S</td>
			<td >Lambda Exonuclease Digestion on Beads (Section 11.2)</td>
		</tr>
		<tr >
			<td >Ligase Enhancer</td>
			<td >New England BioLabs</td>
			<td >E7645S</td>
			<td >NEBNext Ultra II DNA Library Kit. Index Adapter Ligation on Beads (Section 9.1) and Universal Adapter Ligation (Section 16.1)</td>
		</tr>
		<tr >
			<td >Ligase Master Mix</td>
			<td >New England BioLabs</td>
			<td >E7645S</td>
			<td >NEBNext Ultra II DNA Library Kit. Index Adapter Ligation on Beads (Section 9.1) and Universal Adapter Ligation (Section 16.1)</td>
		</tr>
		<tr >
			<td >Lithium Chloride (LiCl), Reagent grade</td>
			<td >Bioshop</td>
			<td >LIT704</td>
			<td >LiCl Wash Buffer</td>
		</tr>
		<tr >
			<td >Magnetic beads for ChIP (Dynabeads Protein G)</td>
			<td >Dynabeads Protein G (magnetic beads for ChIP)</td>
			<td >Dynabeads Protein G (magnetic beads for ChIP)</td>
			<td >Antibody incubation with beads (Section 5)</td>
		</tr>
		<tr >
			<td >Magnetic beads for DNA purification (AMPure XP Beads)</td>
			<td >Beckman Coulter</td>
			<td >A63880</td>
			<td >DNA Extraction (Section 13.3) and DNA Clean-up (Section 17.1)</td>
		</tr>
		<tr >
			<td >Magnetic rack (DynaMag-2 Magnet)</td>
			<td >Invitrogen</td>
			<td >12321D</td>
			<td >Used in many steps in Sections: 5 - 11, 13</td>
		</tr>
		<tr >
			<td >MinElute Gel Extraction Kit</td>
			<td >Qiagen&#160;</td>
			<td >28604</td>
			<td >Gel Purification of PCR Amplified DNA (Section 19.2)</td>
		</tr>
		<tr >
			<td >N-Lauroylsarcosine sodium salt solution, 30% aqueous solution, &#8805;97.0% (HPLC)</td>
			<td >Sigma</td>
			<td >61747</td>
			<td >Lysis Buffer 3</td>
		</tr>
		<tr >
			<td >Octylphenol Ethoxylate (IGEPAL CA630)</td>
			<td >BioShop</td>
			<td >NON999</td>
			<td >Lysis Buffer 1 and LiCl Wash Buffer</td>
		</tr>
		<tr >
			<td >Phenol:Chloroform:Isoamyl Alcohol, Biotechnology Grade (25:24:1)</td>
			<td >BioShop</td>
			<td >PHE512</td>
			<td >Checking Sonication (Section 4.3.1)</td>
		</tr>
		<tr >
			<td >phi29 DNA Polymerase</td>
			<td >New England BioLabs</td>
			<td >M0269L</td>
			<td >Fill-in Reaction on Beads (Section 10.2) and Denaturing, Primer Annealing and Primer Extension (Section 14.3 and 14.4)</td>
		</tr>
		<tr >
			<td >Phosphate-Buffered Saline (PBS), 1x&#160;</td>
			<td >Corning</td>
			<td >21040CV</td>
			<td >Harvest, cross-linking and freezing cells (Section 1.3) and Sonicating Chromatin (Section 3.1), Antibody incuation with beads (Section 5.1)</td>
		</tr>
		<tr >
			<td >PowerPac Basic Power Supply</td>
			<td >BioRad</td>
			<td >1645050</td>
			<td >Checking Sonication (Section 4.3.6) and Gel Purification of LM-PCR Amplified DNA (Section 19.1)</td>
		</tr>
		<tr >
			<td >ProFlex PCR System</td>
			<td >Applied Biosystems</td>
			<td >ProFlex PCR System</td>
			<td >Used in Sections: 14.2, 14.4, 15.2, 16.2 and 18.2</td>
		</tr>
		<tr >
			<td >Protein LoBind Tube, 2.0 mL&#160;</td>
			<td >Eppendorf</td>
			<td >22431102</td>
			<td >Antibody Incubation with Beads (Section 5.2) and Chromatin Immunoprecipitation (Section 6.3)</td>
		</tr>
		<tr >
			<td >Proteinase K Solution, RNA Grade</td>
			<td >Invitrogen</td>
			<td >25530049</td>
			<td >Checking Sonication (Section 4.2) and Elution and Reverse Crosslinking (Section 12.3)</td>
		</tr>
		<tr >
			<td >Qubit 4.0 Fluorometer</td>
			<td >Invitrogen</td>
			<td >Q33226</td>
			<td >Gel Purification of PCR Amplified DNA (Section 19.3)</td>
		</tr>
		<tr >
			<td >Quibit dsDNA BR assay kit</td>
			<td >Invitrogen</td>
			<td >Q32853</td>
			<td >Gel Purification of PCR Amplified DNA (Section 19.3)</td>
		</tr>
		<tr >
			<td >Rnase A, Dnase and Protease-free</td>
			<td >Thermo Scientific</td>
			<td >EN0531</td>
			<td >Checking Sonication (Section 4.3.2) and DNA Extraction (Section 13.2)</td>
		</tr>
		<tr >
			<td >Sodium chloride (NaCl), BioReagent&#160;</td>
			<td >Sigma</td>
			<td >S5886</td>
			<td >Lysis Buffer 1-3, High Salt Wash Buffer</td>
		</tr>
		<tr >
			<td >Sodium Dodecyl Sulfate (SDS), Electrophoresis Grade</td>
			<td >BioShop</td>
			<td >SDS001</td>
			<td >Checking Sonication (Section 4.1), High Salt Wash Buffer and ChIP Elution Buffer</td>
		</tr>
		<tr >
			<td >Sonication beads and 15 mL Bioruptor Tubes</td>
			<td >Diagenode</td>
			<td >C01020031</td>
			<td >Sonicating Chromatin (Section 3.1 and 3.2)</td>
		</tr>
		<tr >
			<td >ThermoMixer F1.5&#160;</td>
			<td >Eppendorf</td>
			<td >5384000020</td>
			<td >Section 4.2, 4.3.2, 4.3.5, 8.2, 9.2, 10.3, 11.2, 12.2, 12.3, 13.2 and 16.2</td>
		</tr>
		<tr >
			<td >Trizma hydrochloride solution (Tris-HCl), BioPerformance Certified, 1 M, pH 7.4</td>
			<td >Sigma</td>
			<td >T2194</td>
			<td >10 mM Tris-HCl Buffer</td>
		</tr>
		<tr >
			<td >Trizma hydrochloride solution (Tris-HCl), BioPerformance Certified, 1 M, pH 8.0</td>
			<td >Sigma</td>
			<td >T2694</td>
			<td >Lysis Buffer 2, Lysis Buffer 3, Checking Sonication (Section 4.1), LiCl Wash Buffer and ChIP Elution Buffer</td>
		</tr>
		<tr >
			<td >Ultra II End Repair/dA-Tailing Module (24 rxn -&#62; 120 rxn)</td>
			<td >New England BioLabs</td>
			<td >E7546S</td>
			<td >End Prep Reaction mix and End Prep Enzyme mix. End-repair and dA-Tailing Reaction on Beads (Section 8.2)</td>
		</tr>
		<tr >
			<td >VWR Mini Tube Rocker, Variable Speed</td>
			<td >VWR</td>
			<td >10159-752</td>
			<td >Used in many steps in sections: 1, 2, 5, 6 and 7</td>
		</tr>
		<tr >
			<td >2-[4-(2,4,4-trimethylpentan-2-yl)phenoxy]ethanol, Triton X-100, Reagent Grade</td>
			<td >BioShop</td>
			<td >TRX506</td>
			<td >Lysis Buffer 1, Sonicating Chromatin (Section 3.4) and High Salt Wash Buffer</td>
		</tr>
	</tbody>
</table>

high-resolution mapping of protein-dna interactions in mouse stem cell-derived neurons using chromatin immunoprecipitation-exonuclease (chip-exo)

Identifisering av spesifikke protein-DNA interaksjoner på genomet er viktig for å forstå genregulering. Kromatinimmunoprecipitation kombinert med høy gjennomstrømning sekvensering (ChIP-seq) er mye brukt til å identifisere genom-wide bindende steder av DNA-bindende proteiner. ChIP-seq-metoden er imidlertid begrenset av heterogeniteten i lengden av sonikerte DNA-fragmenter og ikke-spesifikk bakgrunns-DNA, noe som resulterer i lav kartløsning og usikkerhet i DNA-bindende steder. For å overvinne disse begrensningene benytter kombinasjonen av ChIP med exonuclease fordøyelse (ChIP-exo) 5' til 3' exonuclease fordøyelsen for å trimme den heterogeneouststore immunoprecipitated DNA til protein-DNA crosslinking site. Exonuclease behandling eliminerer også ikke-spesifikk bakgrunn DNA. Bibliotek-forberedt og exonuclease-fordøyd DNA kan sendes for høy gjennomstrømning sekvensering. ChIP-exo-metoden muliggjør nær base-pair kartløsning med større deteksjonsfølsomhet og redusert bakgrunnssignal. En optimalisert ChIP-exo-protokoll for pattedyrceller og neste generasjons sekvensering er beskrevet nedenfor.

Figur 2A illustrerer sonikeringsresultater etter cellelysis og sonikering, med ulike sykluser, av motorneuronceller differensiert fra mus ES-celler. Det optimale antallet sonikeringssykluser (for eksempel 12 sykluser i figur 2A) genererte sterk DNA-intensitet i 100-400 bp DNA-fragmenter. Høykvalitets ChIP-exo biblioteker er basert på størrelsen og mengden av fragmentert kromatin DNA. Dermed anbefales optimalisering av sonikering for hver celletype og batch av...

Watch this Scientific Journal Video about High-Resolution Mapping of Protein-DNA Interactions in Mouse Stem Cell-Derived Neurons using Chromatin Immunoprecipitation-Exonuclease ChIP-Exo at JoVE.com

High-Resolution Mapping of Protein-DNA Interactions in Mouse Stem Cell-Derived Neurons using Chromatin Immunoprecipitation-Exonuclease ChIP-Exo

Nøyaktig bestemmelse av proteinbindende steder på tvers av genomet er viktig for å forstå genregulering. Her beskriver vi en genomisk kartleggingsmetode som behandler kromatin-immunoprecipitated DNA med exonuclease fordøyelse (ChIP-exo) etterfulgt av høy gjennomstrømning sekvensering. Denne metoden oppdager protein-DNA-interaksjoner med nær base-pair kartløsning og høyt signal-til-støy-forhold i pattedyrnevroner.

Høyoppløselig kartlegging av protein-DNA interaksjoner i mus stamcelle-avledede nevroner ved hjelp av kromatin immunoprecipitation-exonuclease (ChIP-Exo)

Identification of specific protein-DNA interactions on the genome is important for understanding gene regulation. Chromatin immunoprecipitation coupled ...

The main advantage of our ChIP-exo method is the improved mapping resolution of protein DNA interactions in the cell compared to the conventional chromatin immunoprecipitation method. To prepare protein G magnetic beads for ChIP, mix the magnetic beads until homogeneous. Then add 25 microliters of the magnetic beads to a two milliliter protein low bind tube.Add one milliliter of blocking solution to the beads. Mix well by pipetting, then place the tube on a magnetic rack for one minute. Once the supernatant is clear, remove it.Next, add one milliliter of blocking solution to the beads. Place the tube on a rocking platform at four degrees Celsius and rock for 10 minutes, then briefly spin the tube. Place the tube on the magnetic rack and remove the supernatant.Add 500 microliters of blocking solution to the magnetic beads. Briefly spin the antibody against Islet-1, then add four micrograms of the antibody to the tube containing the magnetic beads. Place the tube containing magnetic beads and Islet-1 antibody on a rocking platform at four degrees Celsius and rock for six to 24 hours.To begin the chromatin immunoprecipitation, wash the antibody-coated beads in one milliliter of blocking solution. Place the tube containing the antibody-coated beads on a rocking platform at four degrees Celsius for five minutes. After briefly spinning, place the tube on a magnetic rack and remove the supernatant.Resuspend the antibody-coated beads in 50 microliters of blocking solution. Add one milliliter of sonicated lysates to the antibody-coated beads, then incubate the sample on a rocking platform at four degrees Celsius overnight. After allowing the sample to incubate overnight, collect liquid from the cap by briefly spinning the tube, then place the tube on a magnetic rack.And after one minute, remove the supernatant carefully with a pipette. Next, perform a series of washes as follows. Add one milliliter of cold wash buffer containing CPI to the sample.Mix the sample on a rocking platform at four degrees Celsius for five minutes. Briefly spin the sample tube, then place on a magnetic rack. After one minute, remove the supernatant with a pipette.For the first enzymatic reaction and repair and DA tailing, add 38 microliters of autoclaved double distilled water to the sample, then add end prep reaction mix and end prep enzyme mix. Mix the contents of the tube by pipetting, then incubate the sample at 20 degrees Celsius for 30 minutes. Next, wash the sample beads with high salt wash buffer, lithium chloride wash buffer, and 10 millimolar Tris hydrogen chloride buffer as described previously.To perform the index adapter ligation, add 27 microliters of cold 10 millimolar Tris hydrogen chloride buffer to the sample. Then add index adapter, ligation enhancer, and ligase master mix. Incubate the sample at 20 degrees Celsius for 15 minutes.Again, wash the sample beads with high salt wash buffer, lithium chloride wash buffer, and 10 millimolar Tris hydrogen chloride buffer. Then add 47 microliters of cold 10 millimolar Tris hydrogen chloride buffer to the sample. To repair the nick in the DNA resulting from the missing phosphodiester bond, add 11.1 microliters of the fill-in mix to the sample.Incubate the sample at 30 degrees Celsius for 20 minutes. After a series of washes, add 50 microliters of cold autoclaved double distilled water to the sample. To digest the ChIP DNA in the five prime to three prime direction, add lambda exonuclease buffer and lambda exonuclease and mix the sample by pipetting.Incubate the sample at 37 degrees Celsius for 30 minutes. After the digestion is complete, repeat the three washes a final time. To elute ChIP sample from the beads, resuspend the sample in 75 microliters of ChIP elution buffer and incubator at 65 degrees Celsius for 15 minutes at 130 times G.Add 2.5 microliters of 20 milligrams per milliliter proteinase K to the sample.Vortex the sample briefly, then incubate overnight at 65 degrees Celsius. Briefly spin the sample and place on a magnetic rack. After one minute, transfer the supernatant to a new 1.5 milliliter tube.Purify and elute the DNA. After purifying the eluted DNA, transfer 16 microliters of the extracted DNA sample to a PCR tube. Add 1.2 microliters of denaturing and primer annealing mix to the sample.Using the program described in table six of the manuscript, denature and anneal primers to the template DNA. Add three microliters of primer extension mix to the sample and run the PCR program described in table seven of the manuscript. Add 4.1 microliters of DA tailing mix to the sample and run the sample using the PCR program in table eight of the manuscript.Then add 21.5 microliters of universal adapter ligation mix to the sample and incubate for 15 minutes at 20 degrees Celsius. Add 29 microliters of LM-PCR mix to the sample, then run the sample using the program from table 10 of the manuscript. Following 18 cycles of LM-PCR, ChIP-exo samples from mouse motor neurons were electrophoresed on a 1.5%agarose gel.The results for ChIP-exo Islet-1 showed amplified DNA libraries around 200 to 400 base pairs indicating that the ChIP-exo libraries were successfully amplified by LM-PCR. The band around 100 base pairs represents artifacts from adapters and PCR primers. The no antibody control demonstrates that non-specific background DNA was digested by the lambda exonuclease treatment.Using ChIP-exo and ChIP-seq, Islet-1 bound locations were identified. The ChIP-exo signal was highly focused at Islet-1 binding sites detecting multiple clustered Islet-1 transcription factor binding patterns. The ChIP-seq signal displayed broader signals indicating that ChIP-exo had higher mapping resolution than ChIP-seq for Islet-1.Multiple transcription factors often bind DNA next to each other as a protein-DNA complex. ChIP-exo allows us to study how multiple transcription factors recognize and regulate target DNA.

Research

JoVE Journal

Genetics

High-Resolution Mapping of Protein-DNA Interactions in Mouse Stem Cell-Derived Neurons using Chromatin Immunoprecipitation-Exonuclease (ChIP-Exo)

Mapping RNA-RNA Interactions Globally Using Biotinylated Psoralen

Kartlegging av RNA-RNA-interaksjoner globalt ved bruk av biotinylert psoralen

Knowing how RNAs interact with themselves and with others is key to understanding RNA based gene regulation in the cell. While examples of RNA-RNA ...

Genome-wide Mapping of Protein-DNA Interactions with ChEC-seq in Saccharomyces cerevisiae

Genome-wide Mapping of Protein-DNA Interactions with ChEC-seq in Saccharomyces cerevisiae

Genom-brede kartlegging av protein-DNA-interaksjoner med ChEC-seq i<em&gt; Saccharomyces cerevisiae</em

Genome-wide mapping of protein-DNA interactions is critical for understanding gene regulation, chromatin remodeling, and other chromatin-resident ...

Chromatin Immunoprecipitation (ChIP) in Mouse T-cell Lines

Chromatin Immunoprecipitation ChIP in Mouse T-cell Lines

Kromatinimmunpresipitasjon (ChIP) i mus-T-cellelinjer

Signaling pathways regulate gene expression programs via the modulation of the chromatin structure at different levels, such as by post-translational ...

Retroviral Scanning: Mapping MLV Integration Sites to Define Cell-specific Regulatory Regions

Retroviral skanning: Mapping MLV Integrering Sites for å definere Cell-spesifikke Regulatory Regioner

Moloney murine leukemia (MLV) virus-based retroviral vectors integrate predominantly in acetylated enhancers and promoters. For this reason, mLV ...

High Resolution Fluorescent In Situ Hybridization in Drosophila Embryos and Tissues Using Tyramide Signal Amplification

High Resolution Fluorescent In Situ Hybridization in Drosophila Embryos and Tissues Using Tyramide Signal Amplification

Høy oppløsning fluorescerende In Situ hybridisering i Drosophila embryoer og vev med Tyramide Signal forsterkning

In our efforts to determine the patterns of expression and subcellular localization of Drosophila RNAs on a genome-wide basis, and in a variety of ...

Mapping Genome-wide Accessible Chromatin in Primary Human T Lymphocytes by ATAC-Seq

Kartlegging genomet hele tilgjengelig Chromatin i primære menneskelige T-lymfocytter av ATAC-Seq

Assay for Transposase-Accessible Chromatin with high-throughput sequencing (ATAC-seq) is a method used for the identification of open (accessible) regions ...

Promoter Capture Hi-C: High-resolution, Genome-wide Profiling of Promoter Interactions

Promotoren fange Hei-C: Med høy oppløsning, genomet-bred profilering av arrangøren interaksjoner

The three-dimensional organization of the genome is linked to its function. For example, regulatory elements such as transcriptional enhancers control the ...

CRISPR-Mediated Reorganization of Chromatin Loop Structure

CRISPR-mediert reorganisering av Chromatin Loop struktur

Recent studies have clearly shown that long-range, three-dimensional chromatin looping interactions play a significant role in the regulation of gene ...

High-Resolution Comparison of Bacterial Conjugation Frequencies

Høyoppløselig sammenligning av bakteriell Bøyning frekvenser

Bacterial conjugation is an important step in the horizontal transfer of antibiotic resistance genes via a conjugative DNA element. In-depth comparisons ...

Chromatin Immunoprecipitation Assay Using Micrococcal Nucleases in Mammalian Cells

Kromatin Immunutfelling analysen bruke Micrococcal Nukleaser i pattedyrceller

To express cellular phenotypes in organisms, living cells execute gene expression accordingly, and transcriptional programs play a central role in gene ...