Name: a reporter based cellular assay for monitoring splicing efficiency
Uploaded: 2021-09-15T14:00:00
Description: Watch this Scientific Journal Video about A Reporter Based Cellular Assay for Monitoring Splicing Efficiency at JoVE.com

Dette arbeidet ble støttet av midler til S.S. fra National Institutes of Health (R21CA170786 og R01GM127464) og American Cancer Society (Institutional Research Grant 74-001-34-IRG) og til S.S. og W.M. fra Valley Research Partnership Program (P1-4009 og VRP77). Innholdet er utelukkende forfatternes ansvar og representerer ikke nødvendigvis de offisielle synspunktene til National Institutes of Health.

1. Reagenser og buffere
MERK: All sterilisering ved hjelp av vakuumfiltre skal utføres med 0,2 μm polyetersulfonmembran (PES) i et biosikkerhetsskap.
<ol><li>Forbered RNase-fritt vann ved å tilsette 1,0 ml dietylpyrokarbonat (DEPC) til 1,0 L deionisert vann, bland i minst 1 time ved romtemperatur (RT), autoklaver to ganger, og avkjøl deretter til RT før bruk.</li>
	<li>Forbered Dulbecco's Modified Eagle Medium (DMEM) ved å blande en pakke DMEM pulver (13,4 g), 3,7 g natriumbikarbonat, ...

<ol>
	<li>Zhuang, Y., Weiner, A. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+compensatory+base+change+in+U1+snRNA+suppresses+a+5'+splice+site+mutation.">A compensatory base change in U1 snRNA suppresses a 5' splice site mutation.</a> Cell. 46 (6), 827-835 (1986).</li><li>Scotti, M. M., Swanson, M. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=RNA+mis-splicing+in+disease.">RNA mis-splicing in disease.</a> Nature Review Genetics. 17 (1), 19-32 (2016).</li><li>Ward, A. J., Cooper, T. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+pathobiology+of+splicing.">The pathobiology of splicing.</a> Journal of Pathology. 220 (2), 152-163 (2010).</li><li>Scalet, D., 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=Disease-causing+variants+of+the+conserved++2T+of+5'+splice+sites+can+be+rescued+by+engineered+U1snRNAs.">Disease-causing variants of the conserved +2T of 5' splice sites can be rescued by engineered U1snRNAs.</a> Human Mutatation. 40 (1), 48-52 (2019).</li><li>Yamazaki, N., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Use+of+modified+U1+small+nuclear+RNA+for+rescue+from+exon+7+skipping+caused+by+5'-splice+site+mutation+of+human+cathepsin+A+gene.">Use of modified U1 small nuclear RNA for rescue from exon 7 skipping caused by 5'-splice site mutation of human cathepsin A gene.</a> Gene. 677, 41-48 (2018).</li><li>Yanaizu, M., Sakai, K., Tosaki, Y., Kino, Y., Satoh, J. I. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Small+nuclear+RNA-mediated+modulation+of+splicing+reveals+a+therapeutic+strategy+for+a+TREM2+mutation+and+its+post-transcriptional+regulation.">Small nuclear RNA-mediated modulation of splicing reveals a therapeutic strategy for a TREM2 mutation and its post-transcriptional regulation.</a> Science Reports. 8 (1), 6937 (2018).</li><li>Balestra, D., 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=Splicing+mutations+impairing+CDKL5+expression+and+activity+can+be+efficiently+rescued+by+U1snRNA-based+therapy.">Splicing mutations impairing CDKL5 expression and activity can be efficiently rescued by U1snRNA-based therapy.</a> International Journal of Molecular Sciences. 20 (17), 20174130 (2019).</li><li>Donadon, I., 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=Exon-specific+U1+snRNAs+improve+ELP1+exon+20+definition+and+rescue+ELP1+protein+expression+in+a+familial+dysautonomia+mouse+model.">Exon-specific U1 snRNAs improve ELP1 exon 20 definition and rescue ELP1 protein expression in a familial dysautonomia mouse model.</a> Human Molecular Genetics. 27 (14), 2466-2476 (2018).</li><li>Desjardins, P., Conklin, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=NanoDrop+microvolume+quantitation+of+nucleic+acids.">NanoDrop microvolume quantitation of nucleic acids.</a> Journal of Visualized Experiments. (45), e2565 (2010).</li><li>Summer, H., Gramer, R., Droge, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Denaturing+urea+polyacrylamide+gel+electrophoresis+(Urea+PAGE).">Denaturing urea polyacrylamide gel electrophoresis (Urea PAGE).</a> Journal of Visualized Experiments. (32), e1485 (2009).</li><li>Dominski, Z., Kole, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Selection+of+splice+sites+in+pre-mRNAs+with+short+internal+exons.">Selection of splice sites in pre-mRNAs with short internal exons.</a> Molecular Cell Biology. 11 (12), 6075-6083 (1991).</li><li>Amir-Ahmady, B., Boutz, P. L., Markovtsov, V., Phillips, M. L., Black, D. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Exon+repression+by+polypyrimidine+tract+binding+protein.">Exon repression by polypyrimidine tract binding protein.</a> RNA. 11 (5), 699-716 (2005).</li><li>Le Guedard-Mereuze, 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=Sequence+contexts+that+determine+the+pathogenicity+of+base+substitutions+at+position++3+of+donor+splice-sites.">Sequence contexts that determine the pathogenicity of base substitutions at position +3 of donor splice-sites.</a> Human Mutation. 30 (9), 1329-1339 (2009).</li><li>Sharma, S., Wongpalee, S. P., Vashisht, A., Wohlschlegel, J. A., Black, D. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Stem-loop+4+of+U1+snRNA+is+essential+for+splicing+and+interacts+with+the+U2+snRNP-specific+SF3A1+protein+during+spliceosome+assembly.">Stem-loop 4 of U1 snRNA is essential for splicing and interacts with the U2 snRNP-specific SF3A1 protein during spliceosome assembly.</a> Genes and Development. 28 (22), 2518-2531 (2014).</li><li>Steitz, J. A., 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=.">.</a> Functions of the abundant U-snRNPs. Structure and function of major and minor small nuclear ribonucleoprotein particles. , 115-154 (1988).</li><li>Fortes, P., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Inhibiting+expression+of+specific+genes+in+mammalian+cells+with+5'+end-mutated+U1+small+nuclear+RNAs+targeted+to+terminal+exons+of+pre-mRNA.">Inhibiting expression of specific genes in mammalian cells with 5' end-mutated U1 small nuclear RNAs targeted to terminal exons of pre-mRNA.</a> Proceedings of the National Academy of Sciences U.S.A. 100 (14), 8264-8269 (2003).</li><li>Roca, X., 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=Widespread+recognition+of+5'+splice+sites+by+noncanonical+base-pairing+to+U1+snRNA+involving+bulged+nucleotides.">Widespread recognition of 5' splice sites by noncanonical base-pairing to U1 snRNA involving bulged nucleotides.</a> Genes and Development. 26 (10), 1098-1109 (2012).</li><li>Roca, X., Krainer, A. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Recognition+of+atypical+5'+splice+sites+by+shifted+base-pairing+to+U1+snRNA.">Recognition of atypical 5' splice sites by shifted base-pairing to U1 snRNA.</a> Nature Structural Molecular Biology. 16 (2), 176-182 (2009).</li><li>Taladriz-Sender, A., Campbell, E., Burley, G. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Splice-switching+small+molecules:+A+new+therapeutic+approach+to+modulate+gene+expression.">Splice-switching small molecules: A new therapeutic approach to modulate gene expression.</a> Methods. 167, 134-142 (2019).</li><li>Hamid, F. M., Makeyev, E. V. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+mechanism+underlying+position-specific+regulation+of+alternative+splicing.">A mechanism underlying position-specific regulation of alternative splicing.</a> Nucleic Acids Research. 45 (21), 12455-12468 (2017).</li><li>Martelly, W., 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=Synergistic+roles+for+human+U1+snRNA+stem-loops+in+pre-mRNA+splicing.">Synergistic roles for human U1 snRNA stem-loops in pre-mRNA splicing.</a> RNA Biology. , 1-18 (2021).</li></ol>

Analysen kan tilpasses for skjøteanalyse i andre cellelinjer enn HeLa, men faktorer som påvirker transfeksjonseffektiviteten, for eksempel cellesammenstrømning og mengde DNA, må kanskje optimaliseres. Konstruereforholdet mellom reporter og U1 er en annen kritisk parameter som kanskje må bestemmes avhengig av uttrykksnivåene som observeres i andre celletyper. Kvaliteten på ekstrahert RNA er avgjørende for skjøteanalyse; Derfor anbefales bruk av RNase-fritt vann og dekontaminering av overflater med RNase inaktiver...

Pre-mRNA skjøting er et viktig behandlingstrinn som fjerner ikke-koding introner og nøyaktig ligates koding exons å danne modne mRNA. Anerkjennelse av konsensussekvenser ved ekson-intronkryss, referert til som 5′-skjøte sted og 3′-skjøte sted, av komponenter i skjøtemaskineriene initierer skjøteprosessen. U1 liten kjernefysisk ribonucleoprotein (snRNP) gjenkjenner 5′-spleise stedet ved base paring av U1 snRNA til pre-mRNA1. Genetisk arvelige mutasjoner som endrer 5′-spleise sted sekvenser er forbundet med mange sykdommer2,3. Det er spådd at tapet av basepairing av U1 snRNA med mutant 5′-spleise nettsteder forårsaker avvikende skjøting, noe som kan kompromittere oversettelsen av den berørte transkripsjonen. En potensiell terapeutisk tilnærming for å korrigere skjøtefeil innebærer undertrykkelse av mutasjoner ved modifisert U1 snRNA bærer kompenserende nukleotid endringer i sin 5′-region som basepairs med 5′-spleise stedet. Slike modifiserte U1 snRNAer, også referert til som exon spesifikke U1 snRNAs, har vist seg å være effektive i reversering skjøtefeil, noe som resulterer i økt proteinuttrykk fra den reddet mRNA4,5,6,7,8.
Her beskriver vi U1 snRNP komplementeringsanalyse, en reporterbasert cellulær skjøteanalyse som tillater vurdering av effekten av 5′-ss mutasjoner på skjøting av en exon og kan også brukes til utvikling av modifiserte U1 snRNAer for å muliggjøre redning av exon inkludering. Vi tilbyr også protokoller for overvåking av skjøtede reporterutskrifter ved primerutvidelse og RT-PCR, og for å bestemme uttrykket for modifiserte U1 snRNAer ved primerutvidelse og RT-qPCR.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>Reagent Grade Deionized Water</td>
			<td>ThermoFisher Scientific</td>
			<td>23-751628</td>
			<td></td>
		</tr>
		<tr>
			<td>Diethyl pyrocarbonate (DEPC)</td>
			<td>Sigma-Aldrich</td>
			<td>D5758-25ML</td>
			<td></td>
		</tr>
		<tr>
			<td>Dulbecco&#39;s Modified Eagle Medium (DMEM) powder packet</td>
			<td>Gibco</td>
			<td>12100-046</td>
			<td></td>
		</tr>
		<tr>
			<td>Sodium Bicarbonate</td>
			<td>ThermoFisher Scientific</td>
			<td>S233-500</td>
			<td></td>
		</tr>
		<tr>
			<td>Fetal Bovine Serum (FBS), Australian Source, Heat Inactivated</td>
			<td>Omega Scientific</td>
			<td>FB-22</td>
			<td></td>
		</tr>
		<tr>
			<td>Penicillin-Streptomycin (P/S)</td>
			<td>Sigma-Aldrich</td>
			<td>P4458-100ML</td>
			<td></td>
		</tr>
		<tr>
			<td>Sodium Hydroxide, Standard Solution 1.0N</td>
			<td>Sigma-Aldrich</td>
			<td>S2567-16A</td>
			<td></td>
		</tr>
		<tr>
			<td>Hydrochloric Acid, Certified ACS Plus, 36.5 to 38.0%</td>
			<td>ThermoFisher Scientific</td>
			<td>A144-500</td>
			<td></td>
		</tr>
		<tr>
			<td>Disposable PES Bottle Top Filters</td>
			<td>ThermoFisher Scientific</td>
			<td>FB12566510</td>
			<td></td>
		</tr>
		<tr>
			<td>EDTA Disodium Salt Dihydrate</td>
			<td>Amresco</td>
			<td>0105-2.5KG</td>
			<td></td>
		</tr>
		<tr>
			<td>2.5% Trypsin (10x), no phenol red</td>
			<td>ThermoFisher Scientific</td>
			<td>15090046</td>
			<td></td>
		</tr>
		<tr>
			<td>Sodium Chloride</td>
			<td>Fisher Bioreagent</td>
			<td>BP358-212</td>
			<td></td>
		</tr>
		<tr>
			<td>Potassium Chloride</td>
			<td>Fisher Bioreagent</td>
			<td>BP366-1</td>
			<td></td>
		</tr>
		<tr>
			<td>Disodium Hydrogen Phosphate Heptahydrate</td>
			<td>Fisher Bioreagent</td>
			<td>BP332-1</td>
			<td></td>
		</tr>
		<tr>
			<td>Potassium Dihydrogen Phosphate</td>
			<td>Fisher Bioreagent</td>
			<td>BP362-1</td>
			<td></td>
		</tr>
		<tr>
			<td>Transfection medium - Opti-MEM&#8482; I Reduced Serum Medium, no phenol red</td>
			<td>ThermoFisher Scientific</td>
			<td>11058021</td>
			<td></td>
		</tr>
		<tr>
			<td>Transfection Reagent - Lipofectamine&#8482; 2000</td>
			<td>ThermoFisher Scientific</td>
			<td>13778150</td>
			<td></td>
		</tr>
		<tr>
			<td>TRIzol&#8482; Reagent</td>
			<td>ThermoFisher Scientific</td>
			<td>15596018</td>
			<td></td>
		</tr>
		<tr>
			<td>Chloroform (Approx. 0.75% Ethanol as Preservative/Molecular Biology)</td>
			<td>ThermoFisher Scientific</td>
			<td>BP1145-1</td>
			<td></td>
		</tr>
		<tr>
			<td>Ethanol, Absolute (200 Proof), Molecular Biology Grade, Fisher BioReagents</td>
			<td>ThermoFisher Scientific</td>
			<td>BP2818-4</td>
			<td></td>
		</tr>
		<tr>
			<td>Isopropanol, Molecular Biology Grade, Fisher BioReagents</td>
			<td>ThermoFisher Scientific</td>
			<td>BP2618-212</td>
			<td></td>
		</tr>
		<tr>
			<td>Glycogen (5 mg/ml)</td>
			<td>ThermoFisher Scientific</td>
			<td>AM9510</td>
			<td></td>
		</tr>
		<tr>
			<td>Direct-zol RNA Miniprep Kit</td>
			<td>Zymo Research</td>
			<td>R2052</td>
			<td></td>
		</tr>
		<tr>
			<td>ATP, [&#947;-32P]- 6000Ci/mmol 150mCi/ml Lead, 1 mCi</td>
			<td>PerkinElmer</td>
			<td>NEG035C001MC</td>
			<td></td>
		</tr>
		<tr>
			<td>T4 Polynucleotide Kinase</td>
			<td>New England Biolabs</td>
			<td>M0201L</td>
			<td></td>
		</tr>
		<tr>
			<td>Size exclusion beands - Sephadex&#174; G-25</td>
			<td>Sigma-Aldrich</td>
			<td>G2580-10G</td>
			<td></td>
		</tr>
		<tr>
			<td>Size exclusion mini columns</td>
			<td>USA Scientific</td>
			<td>1415-0600</td>
			<td></td>
		</tr>
		<tr>
			<td>pBR322 DNA-MspI Digest</td>
			<td>New England Biolabs</td>
			<td>N3032S</td>
			<td></td>
		</tr>
		<tr>
			<td>Low Molecular Weight Marker, 10-100 nt</td>
			<td>Affymetrix</td>
			<td>76410 100 UL</td>
			<td></td>
		</tr>
		<tr>
			<td>Rnase inactivating reagents - RNaseZAP&#8482;</td>
			<td>Sigma-Aldrich</td>
			<td>R2020-250ML</td>
			<td></td>
		</tr>
		<tr>
			<td>dNTP Mix (10 mM ea)</td>
			<td>ThermoFisher Scientific</td>
			<td>18427013</td>
			<td></td>
		</tr>
		<tr>
			<td>RNaseOUT&#8482; Recombinant Ribonuclease Inhibitor</td>
			<td>ThermoFisher Scientific</td>
			<td>10777019</td>
			<td></td>
		</tr>
		<tr>
			<td>Reverse Transcriptase - M-MLV Reverse Transcriptase</td>
			<td>ThermoFisher Scientific</td>
			<td>28025013</td>
			<td>used for primer extension</td>
		</tr>
		<tr>
			<td>Taq DNA Polymerase</td>
			<td>ThermoFisher Scientific</td>
			<td>10342020</td>
			<td></td>
		</tr>
		<tr>
			<td>Random Hexamers (50 &#181;M)</td>
			<td>ThermoFisher Scientific</td>
			<td>N8080127</td>
			<td></td>
		</tr>
		<tr>
			<td>Real time PCR mix - SYBR&#8482; Select Master Mix</td>
			<td>ThermoFisher Scientific</td>
			<td>4472903</td>
			<td></td>
		</tr>
		<tr>
			<td>SuperScript&#8482; III Reverse Transcriptase</td>
			<td>ThermoFisher Scientific</td>
			<td>18080093</td>
			<td>used for cDNA preparation</td>
		</tr>
		<tr>
			<td>Dithiothreitol (DTT)</td>
			<td>ThermoFisher Scientific</td>
			<td>18080093</td>
			<td></td>
		</tr>
		<tr>
			<td>5X First-Strand Buffer</td>
			<td>ThermoFisher Scientific</td>
			<td>18080093</td>
			<td></td>
		</tr>
		<tr>
			<td>Formamide (&#8805;99.5%)</td>
			<td>ThermoFisher Scientific</td>
			<td>BP228-100</td>
			<td>Review Material Safety Data Sheets</td>
		</tr>
		<tr>
			<td>Bromophenol Blue sodium salt</td>
			<td>Sigma-Aldrich</td>
			<td>114405-5G</td>
			<td></td>
		</tr>
		<tr>
			<td>Xylene Cyanol FF</td>
			<td>Sigma-Aldrich</td>
			<td>2650-17-1</td>
			<td></td>
		</tr>
		<tr>
			<td>Tris Base (White Crystals or Crystalline Powder/Molecular Biology)</td>
			<td>ThermoFisher Scientific</td>
			<td>BP152-5</td>
			<td></td>
		</tr>
		<tr>
			<td>Boric Acid (Crystalline/Electrophoresis)</td>
			<td>ThermoFisher Scientific</td>
			<td>BP168-500</td>
			<td></td>
		</tr>
		<tr>
			<td>Acrylamide: Bis-Acrylamide 19:1 (40% Solution/Electrophoresis)</td>
			<td>ThermoFisher Scientific</td>
			<td>BP1406-1</td>
			<td>Review Material Safety Data Sheets</td>
		</tr>
		<tr>
			<td>Urea (Colorless-to-White Crystals or Crystalline Powder/Mol. Biol.)</td>
			<td>ThermoFisher Scientific</td>
			<td>BP169-212</td>
			<td></td>
		</tr>
		<tr>
			<td>Ammonium peroxodisulphate (APS) &#8805;98%, Pro-Pure, Proteomics Grade</td>
			<td>VWR</td>
			<td>M133-25G</td>
			<td></td>
		</tr>
		<tr>
			<td>Sigmacote</td>
			<td>Sigma-Aldrich</td>
			<td>SL2-100ML</td>
			<td></td>
		</tr>
		<tr>
			<td>N,N,N&#39;,N&#39;-Tetramethylethylenediamine (TEMED) &#8805;99%, Ultrapure</td>
			<td>VWR</td>
			<td>0761-25ML</td>
			<td>Review Material Safety Data Sheets</td>
		</tr>
		<tr>
			<td>Adjustable Slab Gel Systems, Expedeon</td>
			<td>VWR</td>
			<td>ASG-400</td>
			<td></td>
		</tr>
		<tr>
			<td>Vertical Gel Wrap&#8482; Glass Plate Sets, 16.5 x 14.5cm</td>
			<td>VWR</td>
			<td>NGP-125NR</td>
			<td></td>
		</tr>
		<tr>
			<td>Vertical Gel Wrap&#8482; Glass Plate Sets, 16.5 x 22.0cm</td>
			<td>VWR</td>
			<td>NGP-200NR</td>
			<td></td>
		</tr>
		<tr>
			<td>Vertical Gel Wrap&#8482; Glass Plate Sets, 16.5 x 38.7cm</td>
			<td>VWR</td>
			<td>NGP-400NR</td>
			<td></td>
		</tr>
		<tr>
			<td>GE Storage Phosphor Screens</td>
			<td>Sigma-Aldrich</td>
			<td>GE28-9564</td>
			<td></td>
		</tr>
		<tr>
			<td>Typhoon&#8482; FLA 7000 Biomolecular Imager</td>
			<td>GE Healthcare</td>
			<td>28-9610-73 AB</td>
			<td></td>
		</tr>
		<tr>
			<td>Beckman Coulter LS6500 Liquid Scintillation Counter</td>
			<td>GMI</td>
			<td>8043-30-1194</td>
			<td></td>
		</tr>
		<tr>
			<td>C1000 Touch Thermal Cycler</td>
			<td>ThermoFisher Scientific</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>QuantStudio 6 Flex Real-Time PCR Systems</td>
			<td>ThermoFisher Scientific</td>
			<td></td>
			<td></td>
		</tr>
	</tbody>
</table>

a reporter based cellular assay for monitoring splicing efficiency

Under genuttrykk innebærer det viktige trinnet for pre-mRNA-skjøting nøyaktig anerkjennelse av skjøteplasser og effektiv montering av skjøteosomale komplekser for å bli med i eksoner og fjerne introner før cytoplasmatisk eksport av den modne mRNA. Skjøteeffektivitet kan endres ved tilstedeværelse av mutasjoner på skjøteplasser, påvirkning av transvirkende skjøtefaktorer eller aktiviteten til terapeutiske stoffer. Her beskriver vi protokollen for en cellulær analyse som kan brukes til å overvåke skjøteeffektiviteten til en gitt exon. Analysen bruker en tilpasningsdyktig plasmidkodet 3-exon/2-intron minigene reporter, som kan uttrykkes i pattedyrceller ved forbigående transfeksjon. Etter transfeksjon er total cellulær RNA isolert, og effektiviteten av exon skjøting i reporter mRNA bestemmes av enten primer forlengelse eller semi-kvantitativ omvendt transcriptase-polymerase kjedereaksjon (RT-PCR). Vi beskriver hvordan virkningen av sykdom assosiert 5′ skjøte-området mutasjoner kan bestemmes ved å introdusere dem i reporteren; og hvordan undertrykkelsen av disse mutasjonene kan oppnås ved samtransfeksjon med U1 liten kjernefysisk RNA (snRNA) konstruere bærer kompensatoriske mutasjoner i sin 5′ region som basepairs med 5′-spleise steder på exon-intron veikryss i pre-mRNAs. Dermed kan reporteren brukes til utformingen av terapeutiske U1 partikler for å forbedre anerkjennelsen av mutant 5′ skjøte-nettsteder. Innsetting av cis-fungerende regulatoriske nettsteder, for eksempel spleiseforsterker eller lyddempersekvenser, i reporteren kan også brukes til å undersøke rollen til U1 snRNP i regulering formidlet av en bestemt alternativ skjøtefaktor. Til slutt, reporter uttrykker celler kan inkuberes med små molekyler for å bestemme effekten av potensielle terapeutiske på konstitutive pre-mRNA skjøting eller på exons bærer mutant 5′ skjøte steder. Totalt sett kan reporteranalysen brukes til å overvåke skjøteeffektivitet under en rekke forhold for å studere grunnleggende skjøtemekanismer og skjøterelaterte sykdommer.

Den skjøtende reporteren Dup51, en tre exon-to intron minigene, ble avledet fra det menneskelige β-globingenet og har blitt beskrevet tidligere (figur 1A)11,12 . Vi opprettet en mutant reporter, Dup51p, ved å introdusere Usher syndrom assosiert 5'-spleise stedet mutasjoner som forekommer i exon 3 av protocadherin 15 (PCDH15) gene13. 5'-spleiseområdesekvensen ved exon 2-intron 2-krysset ble endret ...

Watch this Scientific Journal Video about A Reporter Based Cellular Assay for Monitoring Splicing Efficiency at JoVE.com

A Reporter Based Cellular Assay for Monitoring Splicing Efficiency

Denne protokollen beskriver en minigene reporteranalyse for å overvåke virkningen av 5'-spleisestedmutasjoner på skjøting og utvikler undertrykkeren U1 snRNA for redning av mutasjonsindusert skjøtehemming. Reporteren og undertrykkeren U1 snRNA-konstruksjoner uttrykkes i HeLa-celler, og skjøting analyseres av primerutvidelse eller RT-PCR.

En reporterbasert mobilanalyse for overvåking av skjøteeffektivitet

During gene expression, the vital step of pre-mRNA splicing involves accurate recognition of splice sites and efficient assembly of spliceosomal complexes ...

Denne protokollen beskriver en cellulær analyse for overvåking av skjøteeffektivitet, ved hjelp av en tilpasningsdyktig administrerende reporter. Denne reporter assay kan brukes til å studere effekten av sykdom Assosierte mutasjoner i Exxon eller skjøte nettsteder, og til å designe terapi, spesielt en partikler, for å forbedre anerkjennelsen av mutant til fem punkts skjøte nettsteder. Passasjen i Hela-celler aspirerer det brukte mediet og inkuberer cellene med tre milliliter 0,2 5% turer i å inneholde en millimolar EDTA, ved 37 grader Celsius i tre minutter.Etter inkubasjon ved syv milliliter fersk DMEM og overfør cellefjæringen til et 10 milliliterrør. Sentrifuger cellene. Deretter resuspenderer cellepelleten i 10 milliliter fersk DMEM, og tallerken cellene på en ny vevskulturrett ved 20% samløp, for forbigående transsfeksjon.Tell helacellene med en ren hemo cytometersklie og lag en suspensjon med en tetthet på 2,5 ganger 10 til femte celler per milliliter, frø en milliliter av cellefjæringen i hver brønn på en 12 brønnplate og inkuber over natten ved 37 grader Celsius. Neste dag aspirerer det brukte mediet og tilsett 800 mikroliter fersk DMEM med serum til platen. Forbered transfeksjonsblandingene og virvel dem i 15 sekunder.Sentrifuger deretter blandingene og inkuber dem ved romtemperatur i fem minutter. Etter inkubasjonen legger du til alle 200 mikroliter av transfeksjonsblandingen i en brønn av den 12 brønn hela celleplaten for å oppnå et sluttvolum på en milliliter per brønn, og inkubere platen ved 37 grader Celsius i 48 timer. De forberedte merkingsreaksjonene inkuberer.Resuspend den 25 kilo Dalton molekylvekt cutoff størrelse utelukkelse perler ved mild virveling i 10 sekunder. Deretter overføres 600 mikroliter av de resuspenderte perlene til en engangs minikolonne, plassert i et 1,5 milliliter oppsamlingsrør, og returner perlene til fire grader Celsius. Sentrifuger kolonnen og kast strømmen gjennom dem.Vask deretter perlene to ganger ved å tilsette 300 mikroliter RNA fritt vann til kolonnen. Etter den andre vasken, overfør minikolonnen til et nytt 1,5 milliliter sentrifugerør, og legg til kinasereaksjonsblandingen til kolonnen. Sentrifuger kolonnen og samle strømmen gjennom inneholder P32 merket oligonukleotider.Tilsett to mikrogram RNA ekstrahert fra helicellene i 200 mikroliter mikro sentrifugerør og tilsett RNA fritt vann for å utgjøre volumet til 6,55 mikroliter. Deretter legger du til 0,9 mikroliter en master mix en til hvert PCR-rør som inneholder RNA-prøvene, og inkuberer rørene først ved 65 grader Celsius i fem minutter, og deretter på is i ett minutt. Deretter ved 2,55 mikroliter blander en master to, til hvert rør som inneholder RNA og master mix en, og inkuberer rørene ved romtemperatur i 10 minutter.Etter inkubasjonen overfør rørene til en termisk syklist og inkuber først ved 50 grader Celsius i 60 minutter, og deretter ved 70 grader Celsius, i 15 minutter. Etter inkubasjonen legger du til 10 mikroliter av 2X formamid RNA-lastfarge til hver prøve, og fortsetter å skille fragmentene med UIA-siden. Percy DNA-syntese.Tilsett to mikrogram RNA ekstrahert fra de transekterte helacellene, i 200 mikroliter mikroncentrifugerør og tilsett RNAs fritt vann for å utgjøre volumet til lave 11 mikroliter. Deretter legger du til to mikroliter, en mester blander en til hver prøve og inkuberer først på 65 grader Celsius i fem minutter, deretter på is i ett minutt. Deretter legger du til syv mikroliter, en mester blander to til hvert rør og inkuberer rørene ved romtemperatur i 10 minutter, etterfulgt av inkubasjon ved 50 grader Celsius i 60 minutter og 70 grader Celsius i 15 minutter.Deretter fortynner PCR C DNA-reaksjonen for å gi en konsentrasjon på 100 nanogram per mikroliter, og overfør en mikroliter av hver CDNA-prøve til nye PCR-rør. Tilsett 10,5 mikroliter av hovedblandingen til hvert rør som inneholder CDNA, og utfør PCR. Bruke en termosykler Etter at PCR er fullført.Tilsett 12,5 mikroliter 2X formamid DNA-lastfarge til hvert rør. Varm opp prøvene ved 95 grader Celsius i fem minutter, og fortsett å utføre en UIA-side. Pipette fem mikroliter fortynnet CDNA i individuelle Brønner av en 96-brønns qpcr plate triplikat.Deretter legger du til 10 mikroliter pcr-blanding i sanntid til hver brønn, forsegler platene med en optisk film og sentrifugerer for å samle reaksjonene på bunnen av brønnene, og deretter utfører qpcr mens du samler terskel kvantifiseringssyklusverdiene til målforsterkning. Før du laster markørene og prøvene, skyll brønnene med TBE-buffer for å fjerne den avgjorte ureaen. Last deretter 10 mikroliter av hver prøve per brønn og kjør gelen på 300 til 500 volt i to til tre timer, eller til xylen når bunnen.Etter elektroforese fjern glassplatene fra elektroforeseapparatet og separer forsiktig de to platene slik at gelen ligger flatt på en av glassoverflatene, overfør gelen til et filterpapir og dekk den med en plastfolie, ved hjelp av en geltørkerstøvsuger tørk gelen ved 80 grader Celsius i 30 minutter, Plasser deretter den tørkede gelen i en fosforavbildningskassett for inkubering over natten ved romtemperatur. Når det uttrykkes i helaceller, uttrykker den kuttende reporteren dup 51 minnijean den modne full lengde transkripsjon der Exxon to er spleiset effektivt. De fem viktigste skjøtestedmutasjonene og dup 51 P reduserer Exxon to inkludering fra 95 til 30%, noe som fører til dannelsen av en kortere transkripsjon.Co-uttrykk for dup 51 P med U15A SNRNA redder Exxon to skjøter, og gjenoppretter dannelsen av full lengde transkripsjon. I motsetning, co-uttrykk med wild type U1 eller U15G variant har ikke lignende effekt på dup 51P skjøting. Påvisning av U15A variant transkripsjoner, ved primær forlengelse bruker U1 syv til 26 oligo nukleotid, som er 20 nukleotider lange og base par nær adenin på femte posisjon av U1 SNRNA.I nærvær av DATP alene tillater U1 syv til 26 å inkorporere to til tre nukleotider for den endogene villtypen U1 SNRNA som gir et 22 eller 23 nukleotid langt produkt. For U15A- og U15G-variantutvidelsen avsluttes etter å ha lagt til en enkelt adenosin som produserer et 21 nukleotidprodukt. Etter normalisering til U2 SNRNA-uttrykk ble transfekterte U1 wild-type U1 5g- og U15A-varianter uttrykt ved tre til fem folder over den endogene SNRNA.Kvaliteten på den ekstraherte RNA er avgjørende for skjøteanalyse. Derfor anbefales bruk av RNA-fritt vann, og dekontaminering av tjenester med RNAs inaktive midler på det sterkeste. Rapportsystemet som er beskrevet her, kan brukes til å studere rollen til U1 SN RNAer i skjøteforskrifter for reverseringseffekt av flashprisspleisemutasjoner for genaktivering ved hjelp av modifiserte U1SN-RNAer.

a-reporter-based-cellular-assay-for-monitoring-splicing-efficiency

Research

Education

JoVE Journal

JoVE Core

Cell Biology

Biochemistry

Unit 1

Transcription: DNA to RNA

SCIENTISTS IN ACTION

A Fluorescence-based Assay of Phospholipid Scramblase Activity

Scramblases translocate phospholipids across the membrane bilayer bidirectionally in an ATP-independent manner. The first scramblase to be identified and biochemically verified was opsin, the apoprotein of the photoreceptor rhodopsin. Rhodopsin is a G protein-coupled receptor localized in rod photoreceptor disc membranes of the retina where it is responsible for the perception of light. Rhodopsin&#39;s scramblase activity does not depend on its ligand 11-cis-retinal, i.e., the apoprotein opsin is also active as a scramblase. Although constitutive and regulated phospholipid scrambling play an important role in cell physiology, only a few phospholipid scramblases have been identified so far besides opsin. Here we describe a fluorescence-based assay of opsin&#39;s scramblase activity. Opsin is reconstituted into large unilamellar liposomes composed of phosphatidylcholine, phosphatidylglycerol and a trace quantity of fluorescent NBD-labeled PC (1-palmitoyl-2-{6-[7-nitro-2-1,3-benzoxadiazole-4-yl)amino]hexanoyl}-sn-glycero-3-phosphocholine). Scramblase activity is determined by measuring the extent to which NBD-PC molecules located in the inner leaflet of the vesicle are able to access the outer leaflet where their fluorescence is chemically eliminated by a reducing agent that cannot cross the membrane. The methods we describe have general applicability and can be used to identify and characterize scramblase activities of other membrane proteins.

We describe a fluorescence-based assay to measure phospholipid scrambling in large unilamellar liposomes reconstituted with opsin.

En fluorescens-baserte analysen av fosfolipid Scramblase aktivitet

Scramblases translocate phospholipids across the membrane bilayer bidirectionally in an ATP-independent manner. The first scramblase to be identified and ...

Electrochemical Detection of Deuterium Kinetic Isotope Effect on Extracellular Electron Transport in Shewanella oneidensis MR-1

Direct electrochemical detection of c-type cytochrome complexes embedded in the bacterial outer membrane (outer membrane c-type cytochrome complexes; OM c-Cyts) has recently emerged as a novel whole-cell analytical method to characterize the bacterial electron transport from the respiratory chain to the cell exterior, referred to as the extracellular electron transport (EET). While the pathway and kinetics of the electron flow during the EET reaction have been investigated, a whole-cell electrochemical method to examine the impact of cation transport associated with EET has not yet been established. In the present study, an example of a biochemical technique to examine the deuterium kinetic isotope effect (KIE) on EET through OM c-Cyts using a model microbe, Shewanella oneidensis MR-1, is described. The KIE on the EET process can be obtained if the EET through OM c-Cyts acts as the rate-limiting step in the microbial current production. To that end, before the addition of D2O, the supernatant solution was replaced with fresh media containing a sufficient amount of the electron donor to support the rate of upstream metabolic reactions, and to remove the planktonic cells from a uniform monolayer biofilm on the working electrode. Alternative methods to confirm the rate-limiting step in microbial current production as EET through OM c-Cyts are also described. Our technique of a whole-cell electrochemical assay for investigating proton transport kinetics can be applied to other electroactive microbial strains.

Electrochemical Detection of Deuterium Kinetic Isotope Effect on Extracellular Electron Transport in Shewanella oneidensis MR-1

Here we present a protocol of whole-cell electrochemical experiments to study the contribution of proton transport to the rate of extracellular electron transport via the outer-membrane cytochromes complex in Shewanella oneidensis MR-1.

Elektrokjemiske gjenkjenning av Deuterium Kinetic isotop effekt på ekstracellulære elektronet Transport Shewanella oneidensis MR-1

Direct electrochemical detection of c-type cytochrome complexes embedded in the bacterial outer membrane (outer membrane c-type cytochrome complexes; OM ...

An In Vitro Assay to Detect tRNA-Isopentenyl Transferase Activity

N6-isopentenyladenosine RNA modifications are functionally diverse and highly conserved among prokaryotes and eukaryotes. One of the most highly conserved N6-isopentenyladenosine modifications occurs at the A37 position in a subset of tRNAs. This modification improves translation efficiency and fidelity by increasing the affinity of the tRNA for the ribosome. Mutation of enzymes responsible for this modification in eukaryotes are associated with several disease states, including mitochondrial dysfunction and cancer. Therefore, understanding the substrate specificity and biochemical activities of these enzymes is important for understanding of normal and pathologic eukaryotic biology. A diverse array of methods has been employed to characterize i6A modifications. Herein is described a direct approach for the detection of isopentenylation by Mod5. This method utilizes incubation of RNAs with a recombinant isopentenyl transferase, followed by RNase T1 digestion, and 1-dimensional gel electrophoresis analysis to detect i6A modifications. In addition, the potential adaptability of this protocol to characterize other RNA-modifying enzymes is discussed.

An In Vitro Assay to Detect tRNA-Isopentenyl Transferase Activity

Here, we describe a protocol for the biochemical characterization of the yeast RNA-modifying enzyme, Mod5, and discuss how this protocol could be applied to other RNA-modifying enzymes.

I Vitro analysen å oppdage tRNA-Isopentenyl Transferase aktivitet

N6-isopentenyladenosine RNA modifications are functionally diverse and highly conserved among prokaryotes and eukaryotes. One of the most highly conserved ...

A High-Throughput Luciferase Assay to Evaluate Proteolysis of the Single-Turnover Protease PCSK9

Proprotein convertase subtilisin/kexin type 9 (PCSK9) is a single-turnover protease which regulates serum low-density lipoprotein (LDL) levels and, consequently, cardiovascular disease. Although PCSK9 proteolysis is required for its full hypercholesterolemic effect, the evaluation of its proteolytic function is challenging: PCSK9 is only known to cleave itself, undergoes only a single turnover, and after proteolysis, retains its substrate in its active site as an auto-inhibitor. The methods presented here describe an assay which overcomes these challenges. The assay focuses on intermolecular proteolysis in a cell-based context and links successful cleavage to the secreted luciferase activity, which can be easily read out in the conditioned medium. Via sequential steps of mutagenesis, transient transfection, and a luciferase readout, the assay can probe PCSK9 proteolysis under conditions of either genetic or molecular perturbation in a high-throughput manner. This system is well suited for both the biochemical evaluation of clinically discovered missense single-nucleotide polymorphisms (SNPs), as well as for the screening of small-molecule inhibitors of PCSK9 proteolysis.

This protocol presents a method to evaluate the proteolytic activity of an intrinsically low-activity, single turnover protease in a cellular context. Specifically, this method is applied to evaluate the proteolytic activity of PCSK9, a key driver of lipid metabolism whose proteolytic activity is required for its ultimate hypercholesterolemic function.

En høy gjennomstrømming Luciferase analysen vurdere proteolyse av Single-omsetning Protease-PCSK9

Proprotein convertase subtilisin/kexin type 9 (PCSK9) is a single-turnover protease which regulates serum low-density lipoprotein (LDL) levels and, ...

Screening for Phytoestrogens using a Cell-based Estrogen Receptor  &#946; Reporter Assay

Plants are a source of food for many animals, and&#160;they can produce thousands of chemicals. Some of these compounds affect physiological processes in the vertebrates that consume them, such as endocrine function. Phytoestrogens, the most well studied endocrine-active phytochemicals, directly interact with the hypothalamo-pituitary gonadal axis of the vertebrate endocrine system. Here we present the novel use of a cell-based assay to screen plant extracts for the presence of compounds that have estrogenic biological activity. This assay uses mammalian cells engineered to highly express estrogen receptor beta (ER&#946;) and that have been transfected with a luciferase gene. Exposure to compounds with estrogenic activity results in the cells producing light. This assay is a reliable and simple way to test for biological estrogenic activity. It has several improvements over transient transfection assays, most notably, ease of use, the stability of the cells, and the sensitivity of the assay.

We have optimized a commercially available estrogen receptor &#946; reporter assay for screening human and nonhuman primate foods for estrogenic activity. We validated this assay by showing that the known estrogenic human food soy registers high, while other foods show no activity.

Screening for fytoøstrogener ved hjelp av en cellebasert østrogenreseptor β Reporter Analyse

Plants are a source of food for many animals, and&#160;they can produce thousands of chemicals. Some of these compounds affect physiological processes in ...

An Electrochemiluminescence-Based Assay for MeCP2 Protein Variants

The ECLIA is a versatile method which is able to quantify endogenous and recombinant protein amounts in a 96-well format. To demonstrate ECLIA efficiency, this assay was used to analyze intrinsic levels of MeCP2 in mouse brain tissue and the uptake of TAT-MeCP2 in human dermal fibroblasts. The MeCP2-ECLIA produces highly accurate and reproducible measurements with low intra- and inter-assay error. In summary, we developed a quantitative method for the evaluation of MeCP2 protein variants that can be utilized in high-throughput screens.

The electrochemiluminescence immunoassay (ECLIA) is a novel approach for quantitative detection of endogenous and exogenously applied MeCP2 protein variants, which produces highly quantitative, accurate and reproducible measurements with low intra- and inter-assay error over a wide working range. Here, the protocol for the MeCP2-ECLIA in a 96-well format is described.

En elektrochemiluminescensbasert analyse for MeCP2 proteinvarianter

The ECLIA is a versatile method which is able to quantify endogenous and recombinant protein amounts in a 96-well format. To demonstrate ECLIA efficiency, ...

Assessment of Cellular Oxidation using a Subcellular Compartment-Specific Redox-Sensitive Green Fluorescent Protein

Measuring the intracellular oxidation/reduction balance provides an overview of the physiological and/or pathophysiological redox status of an organism. Thiols are especially important for illuminating the redox status of cells via their reduced dithiol and oxidized disulfide ratios. Engineered cysteine-containing fluorescent proteins open a new era for redox-sensitive biosensors. One of them, redox-sensitive green fluorescent protein (roGFP), can easily be introduced into cells with adenoviral transduction, allowing the redox status of subcellular compartments to be evaluated without disrupting cellular processes. Reduced cysteines and oxidized cystines of roGFP have excitation maxima at 488 nm and 405 nm, respectively, with emission at 525 nm. Assessing the ratios of these reduced and oxidized forms allows the convenient calculation of redox balance within the cell. In this method article, immortalized human triple-negative breast cancer cells (MDA-MB-231) were used to assess redox status within the living cell. The protocol steps include MDA-MB-231 cell line transduction with adenovirus to express cytosolic roGFP, treatment with H2O2, and assessment of cysteine and cystine ratio with both flow cytometry and fluorescence microscopy.

This protocol describes the assessment of subcellular compartment-specific redox status within the cell. A redox-sensitive fluorescent probe allows convenient ratiometric analysis in intact cells.

Vurdering av cellulær oksidasjon ved hjelp av et subcellulært romspesifikt Redox-Sensitive Green Fluorescerende protein

Measuring the intracellular oxidation/reduction balance provides an overview of the physiological and/or pathophysiological redox status of an organism. ...

Complementation of Splicing Activity by a Galectin-3 - U1 snRNP Complex on Beads

Classic depletion-reconstitution experiments indicate that galectin-3 is a required splicing factor in nuclear extracts. The mechanism of incorporation of galectin-3 into the splicing pathway is addressed in this paper. Sedimentation of HeLa cell nuclear extracts on 12%-32% glycerol gradients yields fractions enriched in an endogenous ~10S particle that contains galectin-3 and U1 snRNP. We now describe a protocol to deplete nuclear extracts of U1 snRNP with concomitant loss of splicing activity. Splicing activity in the U1-depleted extract can be reconstituted by the galectin-3 - U1 snRNP particle trapped on agarose beads covalently coupled with anti-galectin-3 antibodies. The results indicate that the galectin-3 - U1 snRNP - pre-mRNA ternary complex is a functional E complex leading to intermediates and products of the splicing reaction and that galectin-3 enters the splicing pathway through its association with U1 snRNP. The scheme of using complexes affinity- or immuno-selected on beads to reconstitute splicing activity in extracts depleted of a specific splicing factor may be generally applicable to other systems.

This article describes the experimental procedures for (a) depletion of U1 snRNP from nuclear extracts, with concomitant loss of splicing activity; and (b) reconstitution of splicing activity in the U1-depleted extract by galectin-3 - U1 snRNP particles bound to beads covalently coupled with anti-galectin-3 antibodies.

Komplementering av skjøteaktivitet av et Galectin-3 - U1 snRNP-kompleks på perler

Classic depletion-reconstitution experiments indicate that galectin-3 is a required splicing factor in nuclear extracts. The mechanism of incorporation of ...

NMR-Based Fragment Screening in a Minimum Sample but Maximum Automation Mode

Fragment-based screening (FBS) is a well-validated and accepted concept within the drug discovery process both in academia and industry. The greatest advantage of NMR-based fragment screening is its ability not only to detect binders over 7-8 orders of magnitude of affinity but also to monitor purity and chemical quality of the fragments and thus to produce high quality hits and minimal false positives or false negatives. A prerequisite within the FBS is to perform initial and periodic quality control of the fragment library, determining solubility and chemical integrity of the fragments in relevant buffers, and establishing multiple libraries to cover diverse scaffolds to accommodate various macromolecule target classes (proteins/RNA/DNA). Further, an extensive NMR-based screening protocol optimization with respect to sample quantities, speed of acquisition and analysis at the level of biological construct/fragment-space, in condition-space (buffer, additives, ions, pH, and temperature) and in ligand-space (ligand analogues, ligand concentration) is required. At least in academia, these screening efforts have so far been undertaken manually in a very limited fashion, leading to limited availability of screening infrastructure not only in the drug development process but also in the context of chemical probe development. In order to meet the requirements economically, advanced workflows are presented. They take advantage of the latest state-of-the-art advanced hardware, with which the liquid sample collection can be filled in a temperature-controlled fashion into the NMR-tubes in an automated manner. 1H/19F NMR ligand-based spectra are then collected at a given temperature. High-throughput sample changer (HT sample changer) can handle more than 500 samples in temperature-controlled blocks. This together with advanced software tools speeds up data acquisition and analysis. Further, application of screening routines on protein and RNA samples are described to make aware of the established protocols for a broad user base in biomacromolecular research.

Fragment-based screening by NMR is a robust method to rapidly identify small molecule binders to biomacromolecules (DNA, RNA, or proteins). Protocols describing automation-based sample preparation, NMR experiments &#38; acquisition conditions, and analysis workflows are presented. The technique allows for optimal exploitation of both 1H and 19F NMR-active nuclei for detection.

NMR-basert fragmentscreening i et minimumsutvalg, men maksimal automatiseringsmodus

Fragment-based screening (FBS) is a well-validated and accepted concept within the drug discovery process both in academia and industry. The greatest ...

Optical Tweezers to Study RNA-Protein Interactions in Translation Regulation

RNA adopts diverse structural folds, which are essential for its functions and thereby can impact diverse processes in the cell. In addition, the structure and function of an RNA can be modulated by various trans-acting factors, such as proteins, metabolites or other RNAs. Frameshifting RNA molecules, for instance, are regulatory RNAs located in coding regions, which direct translating ribosomes into an alternative open reading frame, and thereby act as gene switches. They may also adopt different folds after binding to proteins or other trans-factors. To dissect the role of RNA-binding proteins in translation and how they modulate RNA structure and stability, it is crucial to study the interplay and mechanical features of these RNA-protein complexes simultaneously.&#160;This work illustrates how to employ single-molecule-fluorescence-coupled optical tweezers to explore the conformational and thermodynamic landscape of RNA-protein complexes at a high resolution. As an example, the interaction of the SARS-CoV-2 programmed ribosomal frameshifting element with the trans-acting factor short isoform of zinc-finger antiviral protein is elaborated. In addition, fluorescence-labeled ribosomes were monitored using the confocal unit, which would ultimately enable the study of translation elongation. The fluorescence coupled OT assay can be widely applied to explore diverse RNA-protein complexes or trans-acting factors regulating translation and could facilitate studies of RNA-based gene regulation.

This protocol presents a complete experimental workflow for studying RNA-protein interactions using optical tweezers. Several possible experimental setups are outlined including the combination of optical tweezers with confocal microscopy.