Questo lavoro è stato sostenuto da una sovvenzione di progetto del Canadian Institute of Health Research (CIHR 365252), della Krembil Foundation e dell'Ontario Research Fund Research Excellence Round 8 (RE08-065). Sampath Kumar Loganathan è il destinatario di una borsa di studio della Canadian Cancer Society (BC-F-16#31919).

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	<li>Beronja, S., Fuchs, E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=RNAi-mediated+gene+function+analysis+in+skin.">RNAi-mediated gene function analysis in skin.</a> Methods in Molecular Biology. 961, 351-361 (2013).</li><li>Beronja, S., Livshits, G., Williams, S., Fuchs, E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Rapid+functional+dissection+of+genetic+networks+via+tissue-specific+transduction+and+RNAi+in+mouse+embryos.">Rapid functional dissection of genetic networks via tissue-specific transduction and RNAi in mouse embryos.</a> Nature Medicine. 16, 821-827 (2010).</li><li>Shalem, O., 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=Genome-scale+CRISPR-Cas9+knockout+screening+in+human+cells.">Genome-scale CRISPR-Cas9 knockout screening in human cells.</a> Science. 343, 84-87 (2014).</li><li>Beronja, 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=RNAi+screens+in+mice+identify+physiological+regulators+of+oncogenic+growth.">RNAi screens in mice identify physiological regulators of oncogenic growth.</a> Nature. 501, 185-190 (2013).</li><li>Loganathan, S. K., 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=Rare+driver+mutations+in+head+and+neck+squamous+cell+carcinomas+converge+on+NOTCH+signaling.">Rare driver mutations in head and neck squamous cell carcinomas converge on NOTCH signaling.</a> Science. 367, 1264-1269 (2020).</li><li>Leemans, C. R., Snijders, P. J. F., Brakenhoff, R. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+molecular+landscape+of+head+and+neck+cancer.">The molecular landscape of head and neck cancer.</a> Nature Reviews Cancer. 18, 269-282 (2018).</li><li>Green, A. C., Olsen, C. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cutaneous+squamous+cell+carcinoma:+an+epidemiological+review.">Cutaneous squamous cell carcinoma: an epidemiological review.</a> British Journal of Dermatology. 177, 373-381 (2017).</li><li>Campbell, J. 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=pathway+network,+and+immunologic+features+distinguishing+squamous+carcinomas.">pathway network, and immunologic features distinguishing squamous carcinomas.</a> Cell Reports. 23, 194-212 (2018).</li><li>Sanjana, N. E., Shalem, O., Zhang, F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Improved+vectors+and+genome-wide+libraries+for+CRISPR+screening.">Improved vectors and genome-wide libraries for CRISPR screening.</a> Nature Methods. 11, 783-784 (2014).</li><li>Geraerts, M., Willems, S., Baekelandt, V., Debyser, Z., Gijsbers, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Comparison+of+lentiviral+vector+titration+methods.">Comparison of lentiviral vector titration methods.</a> BMC Biotechnology. 6, 34 (2006).</li><li>Schramek, 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=Direct+in+vivo+RNAi+screen+unveils+myosin+IIa+as+a+tumor+suppressor+of+squamous+cell+carcinomas.">Direct in vivo RNAi screen unveils myosin IIa as a tumor suppressor of squamous cell carcinomas.</a> Science. 343, 309-313 (2014).</li><li>Platt, R. 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=CRISPR-Cas9+knockin+mice+for+genome+editing+and+cancer+modeling.">CRISPR-Cas9 knockin mice for genome editing and cancer modeling.</a> Cell. 159, 440-455 (2014).</li><li>Langmead, B., Trapnell, C., Pop, M., Salzberg, S. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Ultrafast+and+memory-efficient+alignment+of+short+DNA+sequences+to+the+human+genome.">Ultrafast and memory-efficient alignment of short DNA sequences to the human genome.</a> Genome Biology. 10, 25 (2009).</li><li>Li, 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=MAGeCK+enables+robust+identification+of+essential+genes+from+genome-scale+CRISPR/Cas9+knockout+screens.">MAGeCK enables robust identification of essential genes from genome-scale CRISPR/Cas9 knockout screens.</a> Genome Biology. 15, 554 (2014).</li><li>Winters, I. P., Murray, C. W., Winslow, M. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Towards+quantitative+and+multiplexed+in+vivo+functional+cancer+genomics.">Towards quantitative and multiplexed in vivo functional cancer genomics.</a> Nature Reviews Genetics. 19, 741-755 (2018).</li><li>Rogers, Z. 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=Mapping+the+in+vivo+fitness+landscape+of+lung+adenocarcinoma+tumor+suppression+in+mice.">Mapping the in vivo fitness landscape of lung adenocarcinoma tumor suppression in mice.</a> Nature Genetics. 50, 483-486 (2018).</li><li>Chow, R. 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=AAV-mediated+direct+in+vivo+CRISPR+screen+identifies+functional+suppressors+in+glioblastoma.">AAV-mediated direct in vivo CRISPR screen identifies functional suppressors in glioblastoma.</a> Nature Neuroscience. 20, 1329-1341 (2017).</li><li>Wang, G., 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=Mapping+a+functional+cancer+genome+atlas+of+tumor+suppressors+in+mouse+liver+using+AAV-CRISPR&#8211;mediated+direct+in+vivo+screening.">Mapping a functional cancer genome atlas of tumor suppressors in mouse liver using AAV-CRISPR&#8211;mediated direct in vivo screening.</a> Science Advances. 4, 5508 (2018).</li><li>Chan, K., Tong, A. H. Y., Brown, K. R., Mero, P., Moffat, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Pooled+CRISPR-based+genetic+screens+in+mammalian+cells.">Pooled CRISPR-based genetic screens in mammalian cells.</a> Journal of Visualized Experiments. (151), e59780 (2019).</li><li>Hart, T., 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=High-resolution+CRISPR+screens+reveal+fitness+genes+and+genotype-specific+cancer+liabilities.">High-resolution CRISPR screens reveal fitness genes and genotype-specific cancer liabilities.</a> Cell. 163, 1515-1526 (2015).</li></ol>

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L'editing del genoma CRISPR/Cas9 è stato ampiamente utilizzato in studi in vitro e in vivo per studiare le funzioni geniche e i processi cellulari. La maggior parte degli studi in vivo utilizza cellule modificate dal gene CRISPR/Cas9 innestate in un modello animale (allografto o xenograft). Sebbene questo sia un potente strumento per studiare la genetica del cancro e le funzioni cellulari, manca ancora del microambiente dei tessuti nativi e potrebbe provocare ferite e / o risposte immunitarie.
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Una delle sfide per la ricerca sul cancro nell'era post-genomica è estrarre la grande quantità di dati genomici per le mutazioni geniche causali e identificare i nodi nella rete genica che possono essere mirati terapeuticamente. Mentre le analisi bioinformatiche hanno contribuito immensamente a raggiungere questi obiettivi, stabilire modelli efficienti in vitro e in vivo è un prerequisito per decifrare la complessità dei sistemi biologici e degli stati delle malattie e per consentire lo sviluppo di farmaci. Mentre i modelli convenzionali di topi transgenici sono stati ampiamente utilizzati per studi di genetica del cancro in vivo, la loro natura ad alta intensità di costi, tempo e lavoro ha ampiamente vietato l'analisi sistematica delle centinaia di geni del cancro putativo non rivelato dalla genomica moderna. Per superare questo collo di bottiglia, abbiamo combinato una tecnologia di editing genica guidata da ultrasuoni precedentemente stabilita nella metodologia di iniezione utero1,2 con una tecnologia di editing genico CRISPR / Cas9 (Clustered Regularly Interspaced Short Palindromic Repeats)3 per indurre e studiare simultaneamente mutazioni di perdita di funzione di centinaia di geni nella pelle e nella cavità orale di un singolo topo.
La metodologia qui descritta utilizza iniezioni guidate da ultrasuoni di lentivirus ingegnerizzati nella cavità amniotica degli embrioni di topo viventi al giorno embrionale E9.5. Il carico lentivirale contenente componenti CRISPR/Cas9 trasduce l'ectoderma superficiale monostrato, che successivamente dà origine all'epitelio della pelle e della cavità orale. La pelle è composta da un'epidermide esterna, seguita da membrana basale e derma. L'epidermide è un epitelio stratificato composto da uno strato interno basale, che mantiene il contatto con la membrana basale e ha capacità proliferativa e cellulare. Lo strato basale dà origine agli strati differenziati sopra come strati spinosi, granulari e strato corneo2,4. Studi di tracciamento del lignaggio mostrano che questo metodo CRISPR/Cas9 in vivo diretto manipola geneticamente le cellule staminali residenti nei tessuti all'interno dello strato basale che persistono per tutta l'età adulta. Poiché il lentivirus può essere titolato per trasdurre l'ectoderma superficiale E9.5 a densità clonale, questo metodo può essere utilizzato per generare topi mosaico che ospitano migliaia di cloni discreti a knock-out genico. Il sequenziamento di nuova generazione può quindi essere utilizzato per analizzare l'effetto dell'ablazione genica mediata da CRISPR /Cas9 all'interno di tali cloni in modomultiplexato 5.
Recentemente abbiamo utilizzato questo metodo per valutare la funzione di 484 geni che mostrano mutazioni ricorrenti nel carcinoma a cellule squamose della testa e del collo umano (HNSCC)5. L'HNSCC è un cancro devastante con un alto tasso di mortalità del 40-50% ed è il6 ° cancro più comune in tutto ilmondo 6. L'HNSCC si presenta nei rivestimenti mucosi delle vie aeree superiori o della cavità orale e sono associati al consumo di tabacco e alcol o all'infezione da papillomavirus umano (HPV). Il carcinoma a cellule squamose cutanee (SCC) sono tumori della pelle e rappresentano il secondo tumore più comune nell'uomo7. Cutaneous SCC e HNSCC sono istologicamente e molecolarmente molto simili, con un'alta percentuale di casi che presentano alterazioni in TP53, PIK3CA, NOTCH1 e HRAS8. Mentre ci sono solo una manciata di geni mutati ad alta frequenza, ci sono centinaia di geni trovati mutati a bassa frequenza (< 5%), un fenomeno comunemente indicato come distribuzione a coda lunga. Poiché la maggior parte dei geni a coda lunga manca di convalida biologica o clinica, abbiamo utilizzato questa tecnologia di screening CRISPR in vivo per modellare la perdita di funzione di questi geni nei topi soggetti a tumore con mutazioni sensibilizzanti in p53, Pik3ca o Hras e identificato diversi nuovi geni soppressori del tumore che collaborano con p53, Pik3ca o Hras per innescare lo sviluppo tumorale5.
Qui, descriviamo un protocollo dettagliato per generare librerie di sgRNA CRISPR lentivirale sgRNA multiplexato ed eseguire schermi di knock-out genico CRISPR / Cas9 nell'ectoderma della superficie del mouse. Da notare che questa metodologia può essere adattata per incorporare altre tecnologie di manipolazione genica come l'attivazione CRISPR (CRISPRa) e l'inattivazione CRISPR (CRISPRi) o modificata per indirizzare altri sistemi di organi nel topo per studiare le funzioni geniche.

<table>
	<tbody>
		<tr>
			<td>0.45 micron filter</td>
			<td>Sigma</td>
			<td>S2HVU02RE</td>
			<td></td>
		</tr>
		<tr>
			<td>12k or 92k oligo chip</td>
			<td>Customarray Inc. (Genscript)</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>15 cm cell culture plates</td>
			<td>Corning</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>293FT</td>
			<td>Invitrogen</td>
			<td>R70007</td>
			<td></td>
		</tr>
		<tr>
			<td>293NT</td>
			<td>Systems Biosciences</td>
			<td>LV900A-1</td>
			<td></td>
		</tr>
		<tr>
			<td>Alkaline phosphatase</td>
			<td>NEB</td>
			<td>M0290L</td>
			<td></td>
		</tr>
		<tr>
			<td>Amplicillin</td>
			<td>Fisher Scientific</td>
			<td>BP1760-25</td>
			<td></td>
		</tr>
		<tr>
			<td>ATP</td>
			<td>NEB</td>
			<td>9804S</td>
			<td></td>
		</tr>
		<tr>
			<td>BsmBI</td>
			<td>NEB</td>
			<td>R0580L</td>
			<td></td>
		</tr>
		<tr>
			<td>Chromic gut suture</td>
			<td>Covidien</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Deep sequencing (Next-Seq or Hi-Seq)</td>
			<td>Illumina</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>DNA-cleanup kit</td>
			<td>Zymo Research</td>
			<td>D4008</td>
			<td></td>
		</tr>
		<tr>
			<td>DNAesy Blood and Tissue DNA extraction kit</td>
			<td>Qiagen</td>
			<td>69506</td>
			<td></td>
		</tr>
		<tr>
			<td>Endura electrocompetent cells</td>
			<td>Lucigen</td>
			<td>60242-1</td>
			<td></td>
		</tr>
		<tr>
			<td>Glass Capillaries</td>
			<td>Drummond</td>
			<td>3-000-203-G/X</td>
			<td></td>
		</tr>
		<tr>
			<td>HEK293T cells</td>
			<td>ATCC</td>
			<td>CRL-3216</td>
			<td></td>
		</tr>
		<tr>
			<td>High-Speed Centrifuge</td>
			<td>Beckman Coulter</td>
			<td>MLS-50</td>
			<td></td>
		</tr>
		<tr>
			<td>LB Agar</td>
			<td>Wisent Technologies</td>
			<td>800-011-LG</td>
			<td></td>
		</tr>
		<tr>
			<td>Micropipette puller</td>
			<td>Sutter Instrument</td>
			<td>P97</td>
			<td></td>
		</tr>
		<tr>
			<td>Mineral oil</td>
			<td>Sigma</td>
			<td>M5904</td>
			<td></td>
		</tr>
		<tr>
			<td>Mini-prep plasmid Kit</td>
			<td>Frogga Bio</td>
			<td>PDH300</td>
			<td></td>
		</tr>
		<tr>
			<td>Mouse oxygen anaesthesia system</td>
			<td>Visual Sonics</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Nanoject II micromanipulator</td>
			<td>Drummond</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>NEBuffer 3.1 (Buffer for BsmBI)</td>
			<td>NEB</td>
			<td>R0580L</td>
			<td></td>
		</tr>
		<tr>
			<td>Needle sharpener</td>
			<td>Sutter Instrument</td>
			<td>BV-10</td>
			<td></td>
		</tr>
		<tr>
			<td>Oligo cleanup kit</td>
			<td>Zymo research</td>
			<td>D4060</td>
			<td></td>
		</tr>
		<tr>
			<td>PAGE purified illumina sequencing primer</td>
			<td>IDT DNA</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>PEI (polyethyleneimine)</td>
			<td>Sigma</td>
			<td>408727-100ML</td>
			<td></td>
		</tr>
		<tr>
			<td>Permoplast modeling clay</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Petridish with central opening</td>
			<td>Visual Sonics</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>pMD2.G</td>
			<td>Addgene</td>
			<td>12259</td>
			<td></td>
		</tr>
		<tr>
			<td>psPAX2</td>
			<td>Addgene</td>
			<td>12260</td>
			<td></td>
		</tr>
		<tr>
			<td>Q5 Polymerase 2x Master mix</td>
			<td>NEB</td>
			<td>M0494L</td>
			<td></td>
		</tr>
		<tr>
			<td>Qubit Fluorometric Quantification</td>
			<td>Invitrogen</td>
			<td>Q33327</td>
			<td></td>
		</tr>
		<tr>
			<td>Semicircular Silicone plug</td>
			<td>Corning</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Silicone membrane</td>
			<td>Visual Sonics</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>T4 DNA ligase</td>
			<td>NEB</td>
			<td>M0202L</td>
			<td></td>
		</tr>
		<tr>
			<td>Ultra-centrifuge tubes</td>
			<td>Beckman Coulter</td>
			<td>344058</td>
			<td></td>
		</tr>
		<tr>
			<td>Vevo2000 ultrasound system</td>
			<td>Visual Sonics</td>
			<td></td>
			<td></td>
		</tr>
	</tbody>
</table>

in vivo crispr/cas9 screening to simultaneously evaluate gene function in mouse skin and oral cavity

I modelli di topo geneticamente modificati (GEMM) sono stati fondamentali per valutare la funzione genica, modellare le malattie umane e servire come modello preclinico per valutare le vie terapeutiche. Tuttavia, la loro natura ad alta intensità di tempo, manodopera e costi limita la loro utilità per l'analisi sistematica della funzione genica. I recenti progressi nelle tecnologie di editing del genoma superano tali limitazioni e consentono la rapida generazione di specifiche perturbazioni geniche direttamente all'interno di specifici organi del topo in modo multiplexato e rapido. Qui, descriviamo un metodo basato su CRISPR / Cas9 (Clustered Regularly Interspaced Short Palindromic Repeats) per generare migliaia di cloni gene knock-out all'interno dell'epitelio della pelle e della cavità orale dei topi e fornire un protocollo che dettaglia i passaggi necessari per eseguire uno schermo CRISPR in vivo diretto per i geni   soppressori del tumore. Questo approccio può essere applicato ad altri organi o ad altre tecnologie CRISPR/Cas9 come l'attivazione CRISPR o l'inattivazione CRISPR per studiare la funzione biologica dei geni durante l'omeostasi tissutale o in vari contesti di malattia.

La figura 1A mostra la progettazione degli oligonucleotidi per il multiplexing di diverse librerie CRISPR personalizzate in modo conveniente in un singolo chip oligo da 12k o 92k. Una volta selezionati gli sgRNA (codificati a colori blu), gli oligonucleotidi sono progettati con siti di restrizione (BsmBI di colore arancione) e coppie di primer PCR specifiche della libreria (codificate a colori verdi). Diverse librerie possono essere progettate utilizzando una combinazione unica di coppie di ...

Watch this Scientific Journal Video about In Vivo CRISPR/Cas9 Screening to Simultaneously Evaluate Gene Function in Mouse Skin and Oral Cavity at JoVE.com

In Vivo CRISPR/Cas9 Screening to Simultaneously Evaluate Gene Function in Mouse Skin and Oral Cavity

Qui descriviamo una metodologia di screening CRISPR/Cas9 in vivo rapida e diretta utilizzando iniezioni lentivirali embrionali guidate da ultrasuoni in utero per valutare contemporaneamente le funzioni di diversi geni nella pelle e nella cavità orale dei topi immunocompetenti.

Screening CRISPR/Cas9 in vivo per valutare contemporaneamente la funzione genica nella pelle del topo e nella cavità orale

Genetically modified mouse models (GEMM) have been instrumental in assessing gene function, modeling human diseases, and serving as preclinical model to ...

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Genetics

6.3K Views.  Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital. Qui descriviamo una metodologia di screening CRISPR/Cas9 in vivo rapida e diretta utilizzando iniezioni lentivirali embrionali guidate da ultrasuoni in utero per valutare contemporaneamente le funzioni di diversi geni nella pelle e nella cavità orale dei topi immunocompetenti.

Video: In Vivo CRISPR/Cas9 Screening to Simultaneously Evaluate Gene Function in Mouse Skin and Oral Cavity

QTL Mapping and CRISPR/Cas9 Editing to Identify a Drug Resistance Gene in Toxoplasma gondii

Scientific knowledge is intrinsically linked to available technologies and methods. This article will present two methods that allowed for the identification and verification of a drug resistance gene in the Apicomplexan parasite Toxoplasma gondii, the method of Quantitative Trait Locus (QTL) mapping using a Whole Genome Sequence (WGS) -based genetic map and the method of Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR)/Cas9 -based gene editing. The approach of QTL mapping allows one to test if there is a correlation between a genomic region(s) and a phenotype. Two datasets are required to run a QTL scan, a genetic map based on the progeny of a recombinant cross and a quantifiable phenotype assessed in each of the progeny of that cross. These datasets are then formatted to be compatible with R/qtl software that generates a QTL scan to identify significant loci correlated with the phenotype. Although this can greatly narrow the search window of possible candidates, QTLs span regions containing a number of genes from which the causal gene needs to be identified. Having WGS of the progeny was critical to identify the causal drug resistance mutation at the gene level. Once identified, the candidate mutation can be verified by genetic manipulation of drug sensitive parasites. The most facile and efficient method to genetically modify T. gondii is the CRISPR/Cas9 system. This system comprised of just 2 components both encoded on a single plasmid, a single guide RNA (gRNA) containing a 20 bp sequence complementary to the genomic target and the Cas9 endonuclease that generates a double-strand DNA break (DSB) at the target, repair of which allows for insertion or deletion of sequences around the break site. This article provides detailed protocols to use CRISPR/Cas9 based genome editing tools to verify the gene responsible for sinefungin resistance and to construct transgenic parasites.

QTL Mapping and CRISPR/Cas9 Editing to Identify a Drug Resistance Gene in Toxoplasma gondii

Details are presented on how QTL mapping with a whole genome sequence based genetic map can be used to identify a drug resistance gene in Toxoplasma gondii and how this can be verified with the CRISPR/Cas9 system that efficiently edits a genomic target, in this case the drug resistance gene.

Mapping QTL e modifica CRISPR / Cas9 per identificare un gene di resistenza alla droga in<em&gt; Toxoplasma gondii</em

Scientific knowledge is intrinsically linked to available technologies and methods. This article will present two methods that allowed for the ...

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Selection-dependent and Independent Generation of CRISPR/Cas9-mediated Gene Knockouts in Mammalian Cells

The CRISPR/Cas9 genome engineering system has revolutionized biology by allowing for precise genome editing with little effort. Guided by a single guide RNA (sgRNA) that confers specificity, the Cas9 protein cleaves both DNA strands at the targeted locus. The DNA break can trigger either non-homologous end joining (NHEJ) or homology directed repair (HDR). NHEJ can introduce small deletions or insertions which lead to frame-shift mutations, while HDR allows for larger and more precise perturbations. Here, we present protocols for generating knockout cell lines by coupling established CRISPR/Cas9 methods with two options for downstream selection/screening. The NHEJ approach uses a single sgRNA cut site and selection-independent screening, where protein production is assessed by dot immunoblot in a high-throughput manner. The HDR approach uses two sgRNA cut sites that span the gene of interest. Together with a provided HDR template, this method can achieve deletion of tens of kb, aided by the inserted selectable resistance marker. The appropriate applications and advantages of each method are discussed.

Recent advances in the ability to genetically manipulate somatic cell lines hold great potential for basic and applied research. Here, we present two approaches for CRISPR/Cas9 generated knockout production and screening in mammalian cell lines, with and without the use of selectable markers.

Selezione-dipendente e generazione indipendente di CRISPR / Cas9-mediata Gene Knockouts nelle cellule di mammiferi

The CRISPR/Cas9 genome engineering system has revolutionized biology by allowing for precise genome editing with little effort. Guided by a single guide ...

Primordial Germ Cell Transplantation for CRISPR/Cas9-based Leapfrogging in Xenopus

The creation of mutant lines by genome editing is accelerating genetic analysis in many organisms. CRISPR/Cas9 methods have been adapted for use in the African clawed frog, Xenopus, a longstanding model organism for biomedical research. Traditional breeding schemes for creating homozygous mutant lines with CRISPR/Cas9-targeted mutagenesis have several time-consuming and laborious steps. To facilitate the creation of mutant embryos, particularly to overcome the obstacles associated with knocking out genes that are essential for embryogenesis, a new method called leapfrogging was developed. This technique leverages the robustness of Xenopus embryos to &#34;cut and paste&#34; embryological methods. Leapfrogging utilizes the transfer of primordial germ cells (PGCs) from efficiently-mutagenized donor embryos into PGC-ablated wildtype siblings. This method allows for the efficient mutation of essential genes by creating chimeric animals with wildtype somatic cells that carry a mutant germline. When two F0 animals carrying &#34;leapfrog transplants&#34; (i.e., mutant germ cells) are intercrossed, they produce homozygous, or compound heterozygous, null F1 embryos, thus saving a full generation time to obtain phenotypic data. Leapfrogging also provides a new approach for analyzing maternal effect genes, which are refractory to F0 phenotypic analysis following CRISPR/Cas9 mutagenesis. This manuscript details the method of leapfrogging, with special emphasis on how to successfully perform PGC transplantation.

Primordial Germ Cell Transplantation for CRISPR/Cas9-based Leapfrogging in Xenopus

Genes essential for survival pose technical hurdles for creating mutant lines. Leapfrogging circumvents lethality by combining genome editing with primordial germ cell transplantation to create wild-type animals carrying germline mutations. Leapfrogging also permits the efficient generation of homozygous null mutants in the F1 generation. Here, the transplantation step is demonstrated.

Trapianto di cellule germinali primordiali per basati su CRISPR/Cas9 rincorsa in Xenopus

The creation of mutant lines by genome editing is accelerating genetic analysis in many organisms. CRISPR/Cas9 methods have been adapted for use in the ...

A Standard Methodology to Examine On-site Mutagenicity As a Function of Point Mutation Repair Catalyzed by CRISPR/Cas9 and SsODN in Human Cells

Combinatorial gene editing using CRISPR/Cas9 and single-stranded oligonucleotides is an effective strategy for the correction of single-base point mutations, which often are responsible for a variety of human inherited disorders. Using a well-established cell-based model system, the point mutation of a single-copy mutant eGFP gene integrated into HCT116 cells has been repaired using this combinatorial approach. The analysis of corrected and uncorrected cells reveals both the precision of gene editing and the development of genetic lesions, when indels are created in uncorrected cells in the DNA sequence surrounding the target site. Here, the specific methodology used to analyze this combinatorial approach to the gene editing of a point mutation, coupled with a detailed experimental strategy to measuring indel formation at the target site, is outlined. This protocol outlines a foundational approach and workflow for investigations aimed at developing CRISPR/Cas9-based gene editing for human therapy. The conclusion of this work is that on-site mutagenesis takes place as a result of CRISPR/Cas9 activity during the process of point mutation repair. This work puts in place a standardized methodology to identify the degree of mutagenesis, which should be an important and critical aspect of any approach destined for clinical implementation.

This protocol outlines the workflow of a CRISPR/Cas9-based gene editing system for the repair of point mutations in mammalian cells. Here, we use a combinatorial approach to gene editing with a detailed follow-on experimental strategy for measuring indel formation at the target site&#8212;in essence, analyzing onsite mutagenesis.

Una metodologia Standard per esaminare in loco mutagenicità in funzione della mutazione di punto riparazione catalizzata da CRISPR/Cas9 e SsODN in cellule umane

Combinatorial gene editing using CRISPR/Cas9 and single-stranded oligonucleotides is an effective strategy for the correction of single-base point ...

Microinjection of CRISPR/Cas9 Protein into Channel Catfish, Ictalurus punctatus, Embryos for Gene Editing

The complete genome of the channel catfish, Ictalurus punctatus, has been sequenced, leading to greater opportunities for studying channel catfish gene function. Gene knockout has been used to study these gene functions in vivo. The clustered regularly interspaced short palindromic repeats/CRISPR associated protein 9 (CRISPR/Cas9) system is a powerful tool used to edit genomic DNA sequences to alter gene function. While the traditional approach has been to introduce CRISPR/Cas9 mRNA into the single cell embryos through microinjection, this can be a slow and inefficient process in catfish. Here, a detailed protocol for microinjection of channel catfish embryos with CRISPR/Cas9 protein is described. Briefly, eggs and sperm were collected and then artificial fertilization performed. Fertilized eggs were transferred to a Petri dish containing Holtfreter's solution. Injection volume was calibrated and then guide RNAs/Cas9 targeting the toll/interleukin 1 receptor domain-containing adapter molecule (TICAM 1) gene and rhamnose binding lectin (RBL) gene were microinjected into the yolk of one-cell embryos. The gene knockout was successful as indels were confirmed by DNA sequencing. The predicted protein sequence alterations due to these mutations included frameshift and truncated protein due to premature stop codons.

Microinjection of CRISPR/Cas9 Protein into Channel Catfish, Ictalurus punctatus, Embryos for Gene Editing

A simple and efficient microinjection protocol for gene editing in channel catfish embryos using the CRISPR/Cas9 system is presented. In this protocol, guide RNAs and Cas9 protein were microinjected into the yolk of one-cell embryos. This protocol has been validated by knocking out two channel catfish immune-related genes.

Microinjection di proteine CRISPR/Cas9 in Channel Catfish, Ictalurus punctatus, embrioni per Gene Editing

The complete genome of the channel catfish, Ictalurus punctatus, has been sequenced, leading to greater opportunities for studying channel catfish gene ...

CRISPR/Cas9-mediated Targeted Integration In Vivo Using a Homology-mediated End Joining-based Strategy

As a promising genome editing platform, the CRISPR/Cas9 system has great potential for efficient genetic manipulation, especially for targeted integration of transgenes. However, due to the low efficiency of homologous recombination (HR) and various indel mutations of non-homologous end joining (NHEJ)-based strategies in non-dividing cells, in vivo genome editing remains a great challenge. Here, we describe a homology-mediated end joining (HMEJ)-based CRISPR/Cas9 system for efficient in vivo precise targeted integration. In this system, the targeted genome and the donor vector containing homology arms (~800 bp) flanked by single guide RNA (sgRNA) target sequences are cleaved by CRISPR/Cas9. This HMEJ-based strategy achieves efficient transgene integration in mouse zygotes, as well as in hepatocytes in vivo. Moreover, a HMEJ-based strategy offers an efficient approach for correction of fumarylacetoacetate hydrolase (Fah) mutation in the hepatocytes and rescues Fah-deficiency induced liver failure mice. Taken together, focusing on targeted integration, this HMEJ-based strategy provides a promising tool for a variety of applications, including generation of genetically modified animal models and targeted gene therapies.

CRISPR/Cas9-mediated Targeted Integration In Vivo Using a Homology-mediated End Joining-based Strategy

The clustered regularly interspaced short palindromic repeats/CRISPR associated protein 9 (CRISPR/Cas9) system provides a promising tool for genetic engineering, and opens up the possibility of targeted integration of transgenes. We describe a homology-mediated end joining (HMEJ)-based strategy for efficient DNA targeted integration in vivo and targeted gene therapies using CRISPR/Cas9.

Integrazione mirata CRISPR/Cas9-mediata In Vivo usando una strategia basata su unendo fine omologia-mediata

As a promising genome editing platform, the CRISPR/Cas9 system has great potential for efficient genetic manipulation, especially for targeted integration ...

A Protocol for the Production of Integrase-deficient Lentiviral Vectors for CRISPR/Cas9-mediated Gene Knockout in Dividing Cells

Lentiviral vectors are an ideal choice for delivering gene-editing components to cells due to their capacity for stably transducing a broad range of cells and mediating high levels of gene expression. However, their ability to integrate into the host cell genome enhances the risk of insertional mutagenicity and thus raises safety concerns and limits their usage in clinical settings. Further, the persistent expression of gene-editing components delivered by these integration-competent lentiviral vectors (ICLVs) increases the probability of promiscuous gene targeting. As an alternative, a new generation of integrase-deficient lentiviral vectors (IDLVs) has been developed that addresses many of these concerns. Here the production protocol of a new and improved IDLV platform for CRISPR-mediated gene editing and list the steps involved in the purification and concentration of such vectors is described and their transduction and gene-editing efficiency using HEK-293T cells was demonstrated. This protocol is easily scalable and can be used to generate high titer IDLVs that are capable of transducing cells in vitro and in vivo. Moreover, this protocol can be easily adapted for the production of ICLVs.

We describe the production strategy of integrase-deficient lentiviral vectors (IDLVs) as vehicles for delivering CRISPR/Cas9 to cells. With an ability to mediate quick and robust gene editing in cells, IDLVs present a safer and equally effective vector platform for gene delivery compared to integrase-competent vectors.

Un protocollo per la produzione di vettori lentivirali integrasi-carenti per CRISPR/Cas9-mediata Knockout del Gene nelle cellule in divisione

Lentiviral vectors are an ideal choice for delivering gene-editing components to cells due to their capacity for stably transducing a broad range of cells ...

Efficient Production and Identification of CRISPR/Cas9-generated Gene Knockouts in the Model System Danio rerio

Characterization of the clustered, regularly interspaced, short, palindromic repeat (CRISPR) system of Streptococcus pyogenes has enabled the development of a customizable platform to rapidly generate gene modifications in a wide variety of organisms, including zebrafish. CRISPR-based genome editing uses a single guide RNA (sgRNA) to target a CRISPR-associated (Cas) endonuclease to a genomic DNA (gDNA) target of interest, where the Cas endonuclease generates a double-strand break (DSB). Repair of DSBs by error-prone mechanisms lead to insertions and/or deletions (indels). This can cause frameshift mutations that often introduce a premature stop codon within the coding sequence, thus creating a protein-null allele. CRISPR-based genome engineering requires only a few molecular components and is easily introduced into zebrafish embryos by microinjection. This protocol describes the methods used to generate CRISPR reagents for zebrafish microinjection and to identify fish exhibiting germline transmission of CRISPR-modified genes. These methods include in vitro transcription of sgRNAs, microinjection of CRISPR reagents, identification of indels induced at the target site using a PCR-based method called a heteroduplex mobility assay (HMA), and characterization of the indels using both a low throughput and a powerful next-generation sequencing (NGS)-based approach that can analyze multiple PCR products collected from heterozygous fish. This protocol is streamlined to minimize both the number of fish required and the types of equipment needed to perform the analyses. Furthermore, this protocol is designed to be amenable for use by laboratory personal of all levels of experience including undergraduates, enabling this powerful tool to be economically employed by any research group interested in performing CRISPR-based genomic modification in zebrafish.

Efficient Production and Identification of CRISPR/Cas9-generated Gene Knockouts in the Model System Danio rerio

Targeted genome editing in the model system Danio rerio (zebrafish) has been greatly facilitated by the emergence of CRISPR-based approaches. Herein, we describe a streamlined, robust protocol for generation and identification of CRISPR-derived nonsense alleles that incorporates the heteroduplex mobility assay and identification of mutations using next-generation sequencing.

Produzione efficiente e identificazione di CRISPR/Cas9-generato Gene Ko nel sistema modello Danio rerio

Characterization of the clustered, regularly interspaced, short, palindromic repeat (CRISPR) system of Streptococcus pyogenes has enabled the development ...

Highly Efficient Gene Disruption of Murine and Human Hematopoietic Progenitor Cells by CRISPR/Cas9

Advances in the hematopoietic stem cell (HSCs) field have been aided by methods to genetically engineer primary progenitor cells as well as animal models. Complete gene ablation in HSCs required the generation of knockout mice from which HSCs could be isolated, and gene ablation in primary human HSCs was not possible. Viral transduction could be used for knock-down approaches, but these suffered from variable efficacy. In general, genetic manipulation of human and mouse hematopoietic cells was hampered by low efficiencies and extensive time and cost commitments. Recently, CRISPR/Cas9 has dramatically expanded the ability to engineer the DNA of mammalian cells. However, the application of CRISPR/Cas9 to hematopoietic cells has been challenging, mainly due to their low transfection efficiencies, the toxicity of plasmid-based approaches and the slow turnaround time of virus-based protocols.
A rapid method to perform CRISPR/Cas9-mediated gene editing in murine and human hematopoietic stem and progenitor cells with knockout efficiencies of up to 90% is provided in this article. This approach utilizes a ribonucleoprotein (RNP) delivery strategy with a streamlined three-day workflow. The use of Cas9-sgRNA RNP allows for a hit-and-run approach, introducing no exogenous DNA sequences in the genome of edited cells and reducing off-target effects. The RNP-based method is fast and straightforward: it does not require cloning of sgRNAs, virus preparation or specific sgRNA chemical modification. With this protocol, scientists should be able to successfully generate knockouts of a gene of interest in primary hematopoietic cells within a week, including downtimes for oligonucleotide synthesis. This approach will allow a much broader group of users to adapt this protocol for their needs.

A protocol for fast CRISPR/Cas9-mediated gene disruption in mouse and human primary hematopoietic cells is described in this article. Cas9-sgRNA ribonucleoproteins are introduced via electroporation with sgRNAs generated through in vitro transcription and commercial Cas9. High editing efficiencies are achieved with limited time and financial cost.

Rottura del Gene altamente efficiente di cellule progenitrici ematopoietiche Murine ed umane di CRISPR/Cas9

Advances in the hematopoietic stem cell (HSCs) field have been aided by methods to genetically engineer primary progenitor cells as well as animal models. ...

CRISPR/Cas9 Gene Editing to Make Conditional Mutants of Human Malaria Parasite P. falciparum

Malaria is a significant cause of morbidity and mortality worldwide. This disease, which primarily affects those living in tropical and subtropical regions, is caused by infection with Plasmodium parasites. The development of more effective drugs to combat malaria can be accelerated by improving our understanding of the biology of this complex parasite. Genetic manipulation of these parasites is key to understanding their biology; however, historically the genome of P. falciparum has been difficult to manipulate. Recently, CRISPR/Cas9 genome editing has been utilized in malaria parasites, allowing for easier protein tagging, generation of conditional protein knockdowns, and deletion of genes. CRISPR/Cas9 genome editing has proven to be a powerful tool for advancing the field of malaria research. Here, we describe a CRISPR/Cas9 method for generating glmS-based conditional knockdown mutants in P. falciparum. This method is highly adaptable to other types of genetic manipulations, including protein tagging and gene knockouts.

CRISPR/Cas9 Gene Editing to Make Conditional Mutants of Human Malaria Parasite P. falciparum

We describe a method for generating glmS-based conditional knockdown mutants in Plasmodium falciparum using CRISPR/Cas9 genome editing.

CRISPR/Cas9 Gene Editing per rendere la mutanti condizionali del parassita di Malaria umana da p. falciparum

Malaria is a significant cause of morbidity and mortality worldwide. This disease, which primarily affects those living in tropical and subtropical ...