Name: gene knock-in by crispr/cas9 and cell sorting in macrophage and t cell lines
Uploaded: 2021-11-13T13:00:00
Description: Watch this Scientific Journal Video about Gene Knock-in by CRISPR/Cas9 and Cell Sorting in Macrophage and T Cell Lines at JoVE.com

We thank the flow cytometry core facility of Xinxiang Medical University. Development of such technology has been supported by NSFC grants 81601360 to LZ, 81471595 and 32070898 to YL. The work is also supported by Foundation of Henan Educational Committee No. 21IRTSTHN030.

1. Design and Plasmid Construction of sgRNAs Targeting Rosa26 Locus
<ol>
	<li>Design guide RNAs around the desired insertion site
	<ol>
		<li>Ensure that the insertion site for mouse Rosa26 (hereafter designated as mRosa26) knock-in experiments is located in the first intron of mRosa26; this site has been used in previous studies28,29. For knock-in experiments in human cells, ensure that the ...

In our experiments, we demonstrated how to perform knock-in editing in immune cells from construct design to knock-in cell screening and validation using human Jurkat T cells and murine RAW264.7 macrophages as examples. Both T cell and macrophage cell lines are resistant to transfection36,37; however, the problem of low efficiency of CRISPR/Cas9 delivery can be overcome with the aid of fluorescent reporters coupled with cell sorting. This protocol is suitable for...

Immune cells are critical for defense against pathogens. Both innate and adaptive immunity are required for clearance of infectants and maintenance of tissue homeostasis1,2. Cell line models are essential tools for understanding the molecular fundamentals of the mammalian immune system; they are used in in vitro functional assays, such as those modeling human T cell activation, and in determining the function of genetic factors in activating or dampening immune responses3,4. It is important to note that the mammalian immune system is enormously heterogeneous and, equally important, a huge number of molecules control the differentiation, migration, and function of a given cell type5,6.
Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR)/Cas9 genome editing tools allow for genetic manipulation of specific cell types, which facilitates functional annotation of genes in a precise manner7,8. Several published protocols have described the delivery of CRISPR/Cas9 in the form of Cas9-guide RNA complexes known as a ribonucleoproteins (RNPs) in HEK293 cells, Jurkat cell lines, primary T cells9,10, macrophages11,12,13, stem cells14, and others15,16. In these protocols, gene tagging is usually achieved by fusing a fluorescent tag to endogenous proteins17,18. However few attempts have been made to use dual fluorescent reporters, which are compatible with single cell sorting, to facilitate knock-in experiments19,20, particularly in immune cells.
In-depth mechanistic analyses aimed at understanding the functions of a novel genetic factor in immune cells generally require cell-type specific deletion of a gene, genetic rescue experiments, and ideally identification of its interactors. Even though methods for optimization of genetic deletion of genes in immune cells have been published9,15,21, far fewer methods have been reported for introducing knock-in alleles with versatile functions to understand the immune response. Therefore, in this protocol we aim to describe in detail an efficient and highly reproducible protocol to express a protein of interest (POI) at the safe harbor locus Rosa26 in both human and murine immune cell lines. We designed a two-color reporter system to enrich for cells transfected with plasmids expressing CRISPR/Cas9 (DsRed2) and a recombinant DNA template (EBFP2), which can be isolated by cell sorting. Following this protocol, we obtained multiple knock-in lines of the human T cell line Jurkat and murine macrophage RAW264.7 for functional analyses of poorly studied proteins.
As an example, we show in this protocol how to obtain knock-in RAW264.7 macrophages stably expressing human ACE2 (a receptor of SARS-Cov-2)22. Because innate immune cells are involved in the pathogenesis of Covid-1923,24 and human ACE2 is regarded as a major receptor required for viral entry into cells before replication, macrophages with knock-in of human ACE2 can serve as a useful tool for mechanistic studies of viral multiplication inside macrophages. In parallel, we also present an example of knock-in of a gene at the human ROSA26 locus to express the RASGRP1 protein, which was fused at its amino terminus with an affinity Twin-Strep-tag (OST). T cells are key target cells in immune therapies, and an increasing number of studies have focused on manipulation of their responsiveness to cancer25,26. As Rasgrp1 is known to be a key signaling molecule downstream of the T cell receptor and its interactors are not well elucidated27, the OST-RASGRP1 knock-in model provides the foundation for identifying interactors regulating the response of T cells to tumors and infection. Taken together, these tools can be used for Covid-19 studies and the discovery of novel molecules interacting with Rasgrp1.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>Amersham Imager 600</td>
			<td>Ge Healthcare</td>
			<td></td>
			<td>imaging of chemiluminescence</td>
		</tr>
		<tr>
			<td>Ampicillin, sodium salt</td>
			<td>MP Biomedicals</td>
			<td>194526</td>
			<td></td>
		</tr>
		<tr>
			<td>Anti-rabbit IgG, HRP-linked Antibody</td>
			<td>Cell Signaling Technology</td>
			<td>7074</td>
			<td>at 1/5000 dilution</td>
		</tr>
		<tr>
			<td>Anti-RasGRP1 antibody, clone 10.1</td>
			<td>Merck</td>
			<td>MABS146</td>
			<td>1.0 &#956;g/mL of working concentration</td>
		</tr>
		<tr>
			<td>AscI</td>
			<td>New England BioLabs</td>
			<td>R0558S</td>
			<td></td>
		</tr>
		<tr>
			<td>&#946;-Actin (D6A8) Rabbit mAb</td>
			<td>Cell Signaling Technology</td>
			<td>8457</td>
			<td>at 1/1000 dilution</td>
		</tr>
		<tr>
			<td>BamHI-HF</td>
			<td>New England BioLabs</td>
			<td>R3136S</td>
			<td></td>
		</tr>
		<tr>
			<td>BbsI-HF</td>
			<td>New England BioLabs</td>
			<td>R3539S</td>
			<td></td>
		</tr>
		<tr>
			<td>Cellometer Mini Automated Cell Counter</td>
			<td>Nexcelom Bioscience</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>E.coli DH5&#945; Competent Cells</td>
			<td>Takara</td>
			<td>9057</td>
			<td></td>
		</tr>
		<tr>
			<td>DMSO (Dimethyl Sulfoxide)</td>
			<td>MP Biomedicals</td>
			<td>196055</td>
			<td></td>
		</tr>
		<tr>
			<td>DNeasy Blood &#38; Tissue Kits</td>
			<td>Qiagen</td>
			<td>69506</td>
			<td>cell culture reagent</td>
		</tr>
		<tr>
			<td>DPBS (10X), no calcium, no magnesium</td>
			<td>ThermoFisher Scientific</td>
			<td>14200075</td>
			<td></td>
		</tr>
		<tr>
			<td>Dulbecco&#39;s Modified Eagle Medium (DMEM) with high glucose</td>
			<td>HyClone</td>
			<td>SH30022.01</td>
			<td></td>
		</tr>
		<tr>
			<td>EcoRI-HF</td>
			<td>New England BioLabs</td>
			<td>R3101S</td>
			<td></td>
		</tr>
		<tr>
			<td>FACSAria&#8482; Fusion</td>
			<td>BD Biosciences</td>
			<td></td>
			<td>equipped with biosafety cabinet</td>
		</tr>
		<tr>
			<td>FACS Canto flow cytometer</td>
			<td>BD Biosciences</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Falcon 5 ml polystyrene round bottom test tube</td>
			<td>BD Biosciences</td>
			<td>352003</td>
			<td></td>
		</tr>
		<tr>
			<td>Fetal bovine serum (FBS)</td>
			<td>ThermoFisher Scientific</td>
			<td>10099141</td>
			<td></td>
		</tr>
		<tr>
			<td>FlowJo version 10.7</td>
			<td>BD Biosciences</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>GAPDH (D16H11) XP&#160;Rabbit mAb</td>
			<td>Cell Signaling Technology</td>
			<td>5174</td>
			<td>at 1/1000 dilution</td>
		</tr>
		<tr>
			<td>Goat anti-Mouse IgG (H+L) Secondary Antibody, HRP</td>
			<td>ThermoFisher Scientific</td>
			<td>31430</td>
			<td>at 1/5000 dilution</td>
		</tr>
		<tr>
			<td>Immobilon ECL Ultra Western HRP Substrate</td>
			<td>Millipore</td>
			<td>WBKLS0500</td>
			<td></td>
		</tr>
		<tr>
			<td>Immobilon-PSQ PVDF Membrane</td>
			<td>Millipore</td>
			<td>ISEQ00010</td>
			<td></td>
		</tr>
		<tr>
			<td>Jurkat</td>
			<td>ATCC</td>
			<td>TIB-152</td>
			<td>https://www.atcc.org/</td>
		</tr>
		<tr>
			<td>Kanamycin sulfate</td>
			<td>MP Biomedicals</td>
			<td>194531</td>
			<td></td>
		</tr>
		<tr>
			<td>LB agar powder</td>
			<td>ThermoFisher Scientific</td>
			<td>22700041</td>
			<td></td>
		</tr>
		<tr>
			<td>Multi-channel Pipette (30-300 &#956;L)</td>
			<td>Eppendorf, or similar</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Neon Transfection System</td>
			<td>ThermoFisher Scientific</td>
			<td>MPK5000</td>
			<td></td>
		</tr>
		<tr>
			<td>Neon Transfection System, 10 &#956;L kit</td>
			<td>ThermoFisher Scientific</td>
			<td>MPK1096</td>
			<td></td>
		</tr>
		<tr>
			<td>Nunc 15 mL Conical Sterile Centrifuge Tubes</td>
			<td>ThermoFisher Scientific</td>
			<td>339651</td>
			<td></td>
		</tr>
		<tr>
			<td>OneTaq&#174; Hot Start Quick-Load&#174; 2X Master Mix</td>
			<td>New England BioLabs</td>
			<td>(M0489)</td>
			<td>for high GC% template</td>
		</tr>
		<tr>
			<td>PageRuler Prestained Protein Ladder, 10 to 180 kDa</td>
			<td>ThermoFisher Scientific</td>
			<td>26616</td>
			<td></td>
		</tr>
		<tr>
			<td>Pipette tip 0.1-20&#181;l</td>
			<td>Eppendorf, or similar</td>
			<td>0030 075.005</td>
			<td></td>
		</tr>
		<tr>
			<td>Pipette tip 2-200&#181;l</td>
			<td>Eppendorf, or similar</td>
			<td>0030 075.021</td>
			<td></td>
		</tr>
		<tr>
			<td>Pipette tip 50-1000&#181;l</td>
			<td>Eppendorf, or similar</td>
			<td>0030 075.064</td>
			<td></td>
		</tr>
		<tr>
			<td>Plasmid Maxi Kit</td>
			<td>Qiagen</td>
			<td>12163</td>
			<td></td>
		</tr>
		<tr>
			<td>pX458-DsRed2</td>
			<td>Addgene</td>
			<td>112219</td>
			<td></td>
		</tr>
		<tr>
			<td>QIAquick PCR Purification Kit</td>
			<td>Qiagen</td>
			<td>28104</td>
			<td>purify plasmid from restriction digestion</td>
		</tr>
		<tr>
			<td>Q5 Hot Start High-Fidelity 2X Master Mix</td>
			<td>New England BioLabs</td>
			<td>M0494S</td>
			<td></td>
		</tr>
		<tr>
			<td>RAW264.7</td>
			<td>ATCC</td>
			<td>TIB-71</td>
			<td>https://www.atcc.org/</td>
		</tr>
		<tr>
			<td>Recombinant Anti-ACE2 antibody [EPR4435(2)]</td>
			<td>Abcam</td>
			<td>ab108252</td>
			<td>at 1/1000 dilution</td>
		</tr>
		<tr>
			<td>RPMI 1640 Medium</td>
			<td>HyClone</td>
			<td>SH30027.01</td>
			<td></td>
		</tr>
		<tr>
			<td>Strep-Tactin Sepharose beads</td>
			<td>IBA Lifesciences</td>
			<td>2-1201-010</td>
			<td></td>
		</tr>
		<tr>
			<td>Penicillin-Streptomycin</td>
			<td>ThermoFisher Scientific</td>
			<td>15140122</td>
			<td></td>
		</tr>
		<tr>
			<td>SYTOX&#8482; Red Dead Cell Stain, for 633 or 635 nm excitation</td>
			<td>ThermoFisher Scientific</td>
			<td>S34859</td>
			<td></td>
		</tr>
		<tr>
			<td>T4 DNA ligase</td>
			<td>New England BioLabs</td>
			<td>M0202S</td>
			<td></td>
		</tr>
		<tr>
			<td>T4 Polynucleotide Kinase</td>
			<td>New England BioLabs</td>
			<td>M0201S</td>
			<td></td>
		</tr>
		<tr>
			<td>Trypan Blue Solution, 0.4%</td>
			<td>ThermoFisher Scientific</td>
			<td>15250061</td>
			<td></td>
		</tr>
		<tr>
			<td>Trypsin-EDTA solution (0.25%), with phenol red</td>
			<td>ThermoFisher Scientific</td>
			<td>25200056</td>
			<td></td>
		</tr>
		<tr>
			<td>ZOE Fluorescent Cell Imager</td>
			<td>Bio-Rad</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>1.5 mL microtubes, PCR-clean</td>
			<td>Eppendorf, or similar</td>
			<td>0030 125.215</td>
			<td></td>
		</tr>
		<tr>
			<td>24-well Clear TC-treated Multiple Well Plates</td>
			<td>Corning</td>
			<td>3524</td>
			<td></td>
		</tr>
		<tr>
			<td>96-well Clear Flat Bottom Polystyrene TC-treated Microplates</td>
			<td>Corning</td>
			<td>3599</td>
			<td></td>
		</tr>
		<tr>
			<td>96-well Clear Round Bottom TC-treated Microplate</td>
			<td>Corning</td>
			<td>3799</td>
			<td></td>
		</tr>
	</tbody>
</table>

gene knock-in by crispr/cas9 and cell sorting in macrophage and t cell lines

Functional genomics studies of the immune system require genetic manipulations that involve both deletion of target genes and addition of elements to proteins of interest. Identification of gene functions in cell line models is important for gene discovery and exploration of cell-intrinsic mechanisms. However, genetic manipulations of immune cells such as T cells and macrophage cell lines using CRISPR/Cas9-mediated knock-in are difficult because of the low transfection efficiency of these cells, especially in a quiescent state. To modify genes in immune cells, drug-resistance selection and viral vectors are typically used to enrich for cells expressing the CRIPSR/Cas9 system, which inevitably results in undesirable intervention of the cells. In a previous study, we designed dual fluorescent reporters coupled to CRISPR/Cas9 that were transiently expressed after electroporation. This technical solution leads to rapid gene deletion in immune cells; however, gene knock-in in immune cells such as T cells and macrophages without the use of drug-resistance selection or viral vectors is even more challenging. In this article, we show that by using cell sorting to aid selection of cells transiently expressing CRISPR/Cas9 constructs targeting the Rosa26 locus in combination with a donor plasmid, gene knock-in can be achieved in both T cells and macrophages without drug-resistance enrichment. As an example, we show how to express human ACE2, a receptor of SARS-Cov-2, which is responsible for the current Covid-19 pandemic, in RAW264.7 macrophages by performing knock-in experiments. Such gene knock-in cells can be widely used for mechanistic studies.

Following the protocol described above to perform knock-in experiments at the mRosa26 locus using murine RAW264.7 macrophages, we designed a targeting vector to express human ACE2, a receptor for the SARS-Cov-2 virus (Figure 2A). Using a similar design, we generated human Jurkat T cells with knock-in of the OST-tagged RASGRP1 fusion protein (Figure 2C). After transfection of three plasmids, two of which were used for expression of CRISPR/Cas9 (DsRed2; p...

Watch this Scientific Journal Video about Gene Knock-in by CRISPR/Cas9 and Cell Sorting in Macrophage and T Cell Lines at JoVE.com

Gene Knock-in by CRISPR/Cas9 and Cell Sorting in Macrophage and T Cell Lines

This protocol uses fluorescent reporters and cell sorting to simplify knock-in experiments in macrophage and T cell lines. Two plasmids are used for these simplified knock-in experiments, namely a CRISPR/Cas9- and DsRed2-expressing plasmid and a homologous recombination donor plasmid expressing EBFP2, which is permanently integrated at the Rosa26 locus in immune cells.

Functional genomics studies of the immune system require genetic manipulations that involve both deletion of target genes and addition of elements to ...

Research

JoVE Journal

Immunology and Infection

Purification of Specific Cell Population by Fluorescence Activated Cell Sorting (FACS)

Purification of Specific Cell Population by Fluorescence Activated Cell Sorting FACS

Experimental and clinical studies often require highly purified cell populations.  FACS is a technique of choice to purify cell populations of known ...

Retroviral Transduction of T-cell Receptors in Mouse T-cells

T-cell receptors (TCRs) play a central role in the immune system. TCRs on T-cell surfaces can specifically recognize peptide antigens presented by antigen ...

Derivation of Thymic Lymphoma T-cell Lines from Atm-/- and p53-/- Mice

Derivation of Thymic Lymphoma T-cell Lines from Atm-/- and p53-/- Mice

Established cell lines are a critical research tool that can reduce the use of laboratory animals in research. Certain strains of genetically modified ...

Methods to Assess Beta Cell Death Mediated by Cytotoxic T Lymphocytes

Type 1 diabetes (T1D) is a T cell mediated autoimmune disease.  During the pathogenesis, patients become progressively more insulinopenic as 
insulin ...

Generation of Multivirus-specific T Cells to Prevent/treat Viral Infections after Allogeneic Hematopoietic Stem Cell Transplant

Viral infections cause morbidity and mortality in allogeneic hematopoietic stem cell transplant (HSCT) recipients. We and others have successfully ...

Expanding Cytotoxic T Lymphocytes from Umbilical Cord Blood that Target Cytomegalovirus, Epstein-Barr Virus, and Adenovirus

Virus infections after stem cell transplantation are among the most common causes of death, especially after cord blood (CB) transplantation (CBT) where ...

piggyBac Transposon System Modification of Primary Human T Cells

piggyBac Transposon System Modification of Primary Human T Cells

The piggyBac transposon system is naturally active, originally derived from the cabbage looper moth1,2. This non-viral system is plasmid based, most ...

Cell-based Flow Cytometry Assay to Measure Cytotoxic Activity

Cytolytic activity of CD8+ T cells is rarely evaluated. We describe here a new cell-based assay to measure the capacity of antigen-specific CD8+ T cells ...

Mouse Na&#239;ve CD4+ T Cell Isolation and In vitro Differentiation into T Cell Subsets

Mouse NaÃƒÆ’Ã‚Â¯ve CD4+ T Cell Isolation and In vitro Differentiation into T Cell Subsets

Antigen inexperienced (na&#239;ve) CD4+ T cells undergo expansion and differentiation to effector subsets at the time of T cell receptor (TCR) recognition ...

Analyzing the Functions of Mast Cells In Vivo Using 'Mast Cell Knock-in' Mice

Analyzing the Functions of Mast Cells In Vivo Using 'Mast Cell Knock-in' Mice

Mast cells (MCs) are hematopoietic cells which reside in various tissues, and are especially abundant at sites exposed to the external environment, such ...