Name: investigation of genetic dependencies using crispr-cas9-based competition assays
Uploaded: 2019-01-07T14:00:00
Description: Watch this Scientific Journal Video about Investigation of Genetic Dependencies Using CRISPR-Cas9-based Competition Assays at JoVE.com

The pCW-Cas9 plasmid was a gift from Eric Lander &#38; David Sabatini (Addgene plasmid # 50661) and the pKLV2-U6gRNA5(BbsI)-PGKpuro2ABFP-W plasmid from the Yusa lab (Addgene plasmid #67974. We would like to thank the Flow Cytometry core at SBP Medical Discovery Institute for timely help with flow analysis and sorting. We would like to acknowledge the support of the Lady Tata Memorial Foundation to A.D. We would like to also acknowledge the support of the following funding sources: NIH/NCI P30 CA030199 Cancer Center Sponsored Grant, the V-Foundation and the San Diego NCI Cancer Centers (C3) #PTC2017to A.J.D.

1. Generating AML Cell Line Clones with High Expression of Stable and Active Cas9
<ol>
	<li>Production of Cas9 lentivirus
	<ol>
		<li>Day 0: Plate 4 x 106 293T cells in 10 mL of DMEM with 10% fetal bovine serum (FBS) and penicillin and L-glutamine in a 10 cm tissue culture dish in a biosafety Level 2 (BSL2) certified cell culture hood. Place the dish in a 37 &#176;C incubator.</li>
		<li>Day 1: The plated 293T cells should be 70&#8211;80% confluent on day 1. Perform the transfection using th...

<ol>
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In this manuscript, we describe a detailed protocol for conducting a CRISPR-Cas9-based competitive growth assay to investigate the role of candidate genes in AML cell lines using flow-cytometry in human/murine AML cells (Figure 5). The goal of the assay is to identify the effect of gene deletion on maintenance of AML cell proliferation over two to three weeks on a medium-throughput scale. Some critical steps need to be followed carefully to facilitate the scaling up of the described protocol...

The past few decades have seen numerous research efforts focused on identifying the contribution of key molecular pathways in acute myeloid leukemia (AML) pathogenesis. Traditionally, gene-disruption in AML cells has been performed using conditional knockout mice or short-hairpin RNA (shRNA). While knockout mice offer a sophisticated system for spatio-temporal control of gene-deletion, generating gene knockout mice is labor-intensive, time-consuming and expensive. Furthermore, gene-knockouts using recombination strategies is not easily scalable; these strategies do not lend themselves well to the interrogation of several genes in parallel. After the discovery of RNA interference methods to knock-down endogenous mRNAs using small interfering RNA (siRNA) or shRNA, many groups started using RNA interference techniques to investigate the role of specific genes in AML. Since both murine and human AML cells are notoriously difficult to transfect using traditional lipid-based transfection methods, most studies employed lentivirally or retrovirally-encoded shRNA for studying gene function in AML cells. The recent discovery of clustered regularly interspaced short palindromic repeats (CRISPR) and the associated Cas nucleases (CRISPR-Cas9) has revolutionized gene-targeting technologies1,2,3. Using CRISPR-Cas9, specific genes or genomic regions can be deleted, edited or tagged with efficiency and ease. CRISPR-Cas9-based gene-editing is now emerging as the method of choice for investigating genotype-to-phenotype relationships in diverse cell types due to the simplicity, effectiveness, and broad applicability of this technique. CRISPR-Cas9-based methods are also becoming the method of choice in AML, not only for interrogating individual genes, but also as a way to target multiple genes in arrayed or pooled genetic screens aimed at investigating several genes in parallel as potential AML-dependencies4,5,6.
In this manuscript, we describe a simple competitive growth assay for measuring the impact of gene-disruption on the growth of AML cells, based on stable CRISPR-Cas9-mediated gene-editing followed by high-throughput flow cytometry. This method is simple, efficient, and scalable to medium-throughput experiments for investigating the role of several genes in parallel in AML cells.

<table>
	<tbody>
		<tr>
			<td>FLAG-M2 Antibody</td>
			<td>sigma-aldrich</td>
			<td>F3165, lot # SLBS3530V</td>
			<td></td>
		</tr>
		<tr>
			<td>Anti-mouse Antibody</td>
			<td>Invitrogen</td>
			<td>31446, lot # TA2514341</td>
			<td></td>
		</tr>
		<tr>
			<td>SuperSignal West Femto Maximum Sensitivity Substrate</td>
			<td>Thermo Fisher</td>
			<td>34095</td>
			<td></td>
		</tr>
		<tr>
			<td>ChemiDoc Imaging System</td>
			<td>BIO RAD</td>
			<td>17001401</td>
			<td></td>
		</tr>
		<tr>
			<td>Sorvall Legend RT centrifuge</td>
			<td>Thermo Scientific</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Blasticidin</td>
			<td>Thermo Fisher</td>
			<td>R21001</td>
			<td></td>
		</tr>
		<tr>
			<td>SYTOX Red</td>
			<td>Thermo Fisher</td>
			<td>S34859</td>
			<td></td>
		</tr>
		<tr>
			<td>Opti-MEM</td>
			<td>Thermo Fisher</td>
			<td>31985062</td>
			<td></td>
		</tr>
		<tr>
			<td>DMEM</td>
			<td>Thermo Fisher</td>
			<td>11965-092</td>
			<td></td>
		</tr>
		<tr>
			<td>RPMI</td>
			<td>Thermo Fisher</td>
			<td>11875-093</td>
			<td></td>
		</tr>
		<tr>
			<td>Penicillin-Streptomycin</td>
			<td>Thermo Fisher</td>
			<td>15140122</td>
			<td></td>
		</tr>
		<tr>
			<td>L-Glutamine (200 mM)</td>
			<td>Thermo Fisher</td>
			<td>25030081</td>
			<td></td>
		</tr>
		<tr>
			<td>Fetal Bovine Serum (FBS)</td>
			<td>SAFC</td>
			<td>12303C</td>
			<td></td>
		</tr>
		<tr>
			<td>single gRNA vector</td>
			<td>Addgene #67974</td>
			<td>pKLV2-U6gRNA5(BbsI)-PGKpuro2ABFP-W</td>
			<td></td>
		</tr>
		<tr>
			<td>CelLytic Nuclear extraction kit</td>
			<td>sigma-alorich</td>
			<td>NXTRACT</td>
			<td></td>
		</tr>
		<tr>
			<td>XtremeGENE 9</td>
			<td>sigma-alorich</td>
			<td>6365787001</td>
			<td></td>
		</tr>
		<tr>
			<td>Retronectin</td>
			<td>Takara</td>
			<td>T100B</td>
			<td></td>
		</tr>
		<tr>
			<td>Flow cytometer</td>
			<td>BD Biosciences</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>T4 PNK</td>
			<td>NEBioLabs</td>
			<td>M0201S</td>
			<td></td>
		</tr>
		<tr>
			<td>T4 DNA ligation buffer</td>
			<td>NEBioLabs</td>
			<td>B0202S</td>
			<td></td>
		</tr>
		<tr>
			<td>T4 DNA Ligase enzyme</td>
			<td>NEBioLabs</td>
			<td>M0202S</td>
			<td></td>
		</tr>
		<tr>
			<td>Ampicillin</td>
			<td>Fisher scientific</td>
			<td>BP1760-25</td>
			<td></td>
		</tr>
		<tr>
			<td>LB agar</td>
			<td>Fisher scientific</td>
			<td>BP9724-500</td>
			<td></td>
		</tr>
		<tr>
			<td>LB Broth</td>
			<td>Fisher scientific</td>
			<td>BP9731-500</td>
			<td></td>
		</tr>
		<tr>
			<td>Qiagen mini-prep kit</td>
			<td>Qiagen</td>
			<td>27104</td>
			<td></td>
		</tr>
		<tr>
			<td>NanoDrop Spectrophotometer</td>
			<td>Thermo Fisher</td>
			<td>NanoDrop One</td>
			<td></td>
		</tr>
		<tr>
			<td>Recombinant Murine IL-3</td>
			<td>Peprotech</td>
			<td>213-13</td>
			<td></td>
		</tr>
		<tr>
			<td>Recombinant Murine IL-6</td>
			<td>Peprotech</td>
			<td>216-16</td>
			<td></td>
		</tr>
		<tr>
			<td>Recombinant Murine M-CSF</td>
			<td>Peprotech</td>
			<td>315-02</td>
			<td></td>
		</tr>
		<tr>
			<td>Stable competent cells</td>
			<td>NEBiolabs</td>
			<td>C3040I</td>
			<td></td>
		</tr>
		<tr>
			<td>10 cm Tissue Culture dishes</td>
			<td>Fisher Scientific</td>
			<td>353003</td>
			<td></td>
		</tr>
		<tr>
			<td>Cell lysis solution</td>
			<td>Qiagen</td>
			<td>158906</td>
			<td></td>
		</tr>
		<tr>
			<td>Protein precipitation solution</td>
			<td>Qiagen</td>
			<td>158910</td>
			<td></td>
		</tr>
		<tr>
			<td>DNA hydration solution</td>
			<td>Qiagen</td>
			<td>158914</td>
			<td></td>
		</tr>
		<tr>
			<td>QIAquick Gel Extraction Kit</td>
			<td>Qiagen</td>
			<td>28704</td>
			<td></td>
		</tr>
		<tr>
			<td>BbSI</td>
			<td>New England BioLabs</td>
			<td>R0539S</td>
			<td></td>
		</tr>
		<tr>
			<td>APEX 2.0 X Taq Red Master Mix Kit</td>
			<td>Genessee Scientific</td>
			<td>42-138</td>
			<td></td>
		</tr>
		<tr>
			<td>Puromycin</td>
			<td>Fisher scientific</td>
			<td>BP2956100</td>
			<td></td>
		</tr>
		<tr>
			<td>50 mL polypropylene conical tubes</td>
			<td>Fisher scientific</td>
			<td>1495949A</td>
			<td></td>
		</tr>
		<tr>
			<td>15 mL polypropylene conical tubes</td>
			<td>Fisher scientific</td>
			<td>1495970C</td>
			<td></td>
		</tr>
	</tbody>
</table>

investigation of genetic dependencies using crispr-cas9-based competition assays

Gene perturbation studies have been extensively used to investigate the role of individual genes in AML pathogenesis. For achieving complete gene disruption, many of these studies have made use of complex gene knockout models. While these studies with knockout mice offer an elegant and time-tested system for investigating genotype-to-phenotype relationships, a rapid and scalable method for assessing candidate genes that play a role in AML cell proliferation or survival in AML models will help accelerate the parallel interrogation of multiple candidate genes. Recent advances in genome-editing technologies have dramatically enhanced our ability to perform genetic perturbations at an unprecedented scale. One such system of genome editing is the CRISPR-Cas9-based method that can be used to make rapid and efficacious alterations in the target cell genome. The ease and scalability of CRISPR/Cas9-mediated gene-deletion makes it one of the most attractive techniques for the interrogation of a large number of genes in phenotypic assays. Here, we present a simple assay using CRISPR/Cas9 mediated gene-disruption combined with high-throughput flow-cytometry-based competition assays to investigate the role of genes that may play an important role in the proliferation or survival of human and murine AML cell lines.

In our study, we first transduced the MOLM13 human AML cell line that bears the MLL-AF9 translocation with high-titer virus encoding the Cas9-blasticidin lentiviral plasmid. In our hands, bulk unsorted MOLM13-Cas9 cells did not display high level Cas9 expression by Western blotting and also did not perform well when assayed for efficient gene editing-using the method described previously7. Therefore, we proceeded to establish single cell clones and only select the ...

Watch this Scientific Journal Video about Investigation of Genetic Dependencies Using CRISPR-Cas9-based Competition Assays at JoVE.com

Investigation of Genetic Dependencies Using CRISPR-Cas9-based Competition Assays

This manuscript describes a Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR) CRISPR-Cas9-based method for simple and expeditious investigation of the role of multiple candidate genes in Acute Myeloid Leukemia (AML) cell proliferation in parallel. This technique is scalable and can be applied in other cancer cell lines as well.

Gene perturbation studies have been extensively used to investigate the role of individual genes in AML pathogenesis. For achieving complete gene ...

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