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CRISPR modified cell lines

CRISPR modified cell lines

We are using CRISPR gene editing technologies to generate new cell lines as part of the funded project NIH ORIP R24 OD019847 "Next-generation Drosophila cell lines to elucidate the cellular basis of human diseases" (N. Perrimon, PI; A. Simcox, Co-PI).

GFP-tagged knock-in cell lines

As part of the ORIP-funded project, we are making GFP-tagged cell lines, with an emphasis on visualization of various organelles and sub-cellular compartments. The following GFP knock-in cell lines made at the DRSC in collaboration with the Bellne lab are available for distribution by the DGRC in Bloomington, IN. 

Note that the parental cell line is positive for an mCherry fusion and Cas9, as the parental cell line is S2R+-MT::Cas9 (DGRC cell catalog #268), which is described in Viswanatha et al. 2018 (PubMed ID 30051818). This parental cell line was itself derived from DRSC cell line S2R+ NPT005 (DGRC cell catalog #229), which is described in Neumuller et al. 2012 (PubMed ID 22174071).

S2R+ with GFP::Cnx99a. Ordering information: DGRC cell catalog ID #273
S2R+ with GFP::Rab11. Ordering information: DGRC cell catalog ID #274
S2R+ with GFP::Polo. Ordering information: DGRC cell catalog ID #275
S2R+ with GFP::Gmap (clone #4). Ordering information: DGRC cell catalog ID #276
S2R+ with GFP::Gmap (clone $7). Ordering information: DGRC cell catalog ID #277
S2R+ with GFP::Fib (clone #11). Ordering information: DGRC cell catalog ID #278
S2R+ with GFP::Fib (clone #12). Ordering information: DGRC cell catalog ID #279
S2R+ with GFP::Golgin. Ordering information: DGRC cell catalog ID #280
S2R+ with GFP::Arl8. Ordering information: DGRC cell catalog ID #291
S2R+ with GFP::Lam. Ordering information: DGRC cell catalog ID #292
S2R+ with GFP::Spin. Ordering information: DGRC cell catalog ID #293
S2R+ with GFP::Sec23. Ordering information: DGRC cell catalog ID #294
S2R+ with GFP::Tom20. Ordering information: DGRC cell catalog ID #302

These cell lines were made using constructs designed and provided by Kanca and Bellen (Baylor College of Medicine). The cell lines were engineered, isolated, and validated at the DRSC. Validation testing included live-cell imaging, fixed-cell imaging (co-stained with an antibody, when possible), and molecular characterization of the insertion endpoints.

See the file attached below for a slide presentation with images of live and fixed cells, as well as other relevant information about the approach and the resulting GFP-tagged cell lines.

In addition, C-terminal GFP knock-in cell lines were generated as described in a BioRxiv preprint from Bosch et al. (2019) using an 'armless' donor approach. Act5c::GFP, Tub84B::GFP, His2Av::GFP, and Lamin::GFP fusion cell lines were made using this approach and are being shared with the DGRC for distribution to the community.

Knockout cell lines

S2R+-ZnT63C-KO, NHEJ-mediated knockout of ZnT63C. As described in PMID: 29223976. Ordering information: DGRC cell catalog #265.
S2R+-IA2-KO, NHEJ-mediated knockout of ia2. As described in PMID: 29223976. Ordering information: DGRC cell catalog #266.
S2R+-Apc-KO, two independent cell lines made with one method, DGRC cell catalog #271 and DGRC cell catalog #272
S2R+-Apc-KO, one additional cell line made with a different method, DGRC cell catalog #270
S2R+-gig-KO, DGRC cell catalog #297
S2R+-hairy-KO, DGRC cell catalog #298
S2R+-Moe-KO, DGRC cell catalog #303
S2R+-Pex19-KO, DGRC cell catalog #306
S2R+-Pten-KO, DGRC cell catalog #307
S2R+-Slik-KO, DGRC cell catalog #308
S2R+-Tnks-KO, three independent cell lines, DGRC cell catalog #299, DGRC cell catalog #300, and DGRC cell catalog #301
S2R+-Tnks-KO, one additional cell line made with a different method, DGRC cell catalog #304
S2R+-TSC1-KO, DGRC cell catalog #305
S2R+-Yki-KO, DGRC cell catalog #309

These cell lines have been sequence verified as containing only knockout alleles by PCR amplification of the target region followed by next-generation sequencing of the PCR amplicon, contig assembly, and comparison with the wild-type reference sequence (or, for KO alleles generated via knock-in, verified using PCR validation of the insertion allele). We wanted to make sure that the distribution copies of the cell lines are correct. To do this, for a subset of these cell lines, (1) the DGRC prepared genomic DNA from their distribution copies of the cell lines, (2) they shipped that gDNA to the DRSC/TRiP, and (3) we used that gDNA as template for PCR and NGS, and validated that all alleles are predicted to be gene knockout alleles. Information relevant to re-validation in your own lab is provided at the DGRC website.

Did you request GFP-tagged or KO cells from the DGRC and use them in a study? If so, please acknowledge both the cell line developers (DRSC) and the distribtors (DGRC) by citing NIH Grant 5R24OD019847, which supported production of the resource at DRSC/TRiP, and the Drosophila Genome Resource Center, NIH grant 2P40OD010949, as well as relevant pulications.

Slide presentation file -- GFP-tagged cell lines:

smohr_drsc_gfp-tag_websharecopy.pdf12.23 MB

Publications

Raghuvir Viswanatha, Enzo Mameli, Jonathan Rodiger, Pierre Merckaert, Fabiana Feitosa-Suntheimer, Tonya M. Colpitts, Stephanie E. Mohr, Yanhui Hu, and Norbert Perrimon. Working Paper. “Bioinformatic and cell-based tools for pooled CRISPR knockout screening in mosquitos.” bioRxiv. Publisher's VersionAbstract
2021.03.29.437496v2.full_.pdf
Mosquito-borne diseases present a worldwide public health burden. Genome-scale screening tools that could inform our understanding of mosquitos and their control are lacking. Here, we adapt a recombination-mediated cassette exchange system for delivery of CRISPR sgRNA libraries into cell lines from several mosquito species and perform pooled CRISPR screens in an Anopheles cell line. To implement this method, we engineered modified mosquito cell lines, validated promoters and developed bioinformatics tools for multiple mosquito species.Competing Interest StatementThe authors have declared no competing interest.
R. Viswanatha, M. Zaffagni, J. Zirin, N. Perrimon, and S. Kadener. Working Paper. “CRISPR-Cas13 mediated Knock Down in Drosophila cultured cells.” BioRxiv.Abstract
2020.11.01.364166v1.full_.pdf
Manipulation of gene expression is one of the best approaches for studying gene function in vivo. CRISPR-Cas13 has the potential to be a powerful technique for manipulating RNA expression in diverse animal systems in vivo, including Drosophila melanogaster. Studies using Cas13 in mammalian cell lines for gene knockdown showed increased on-target efficiency and decreased off-targeting relative to RNAi. Moreover, catalytically inactive Cas13 fusions can be used to image RNA molecules, install precise changes to the epitranscriptome, or alter splicing. However, recent studies have suggested that there may be limitations to the deployment of these tools in Drosophila, so further optimization of the system is required. Here, we report a new set of PspCas13b and RfxCas13d expression constructs and use these reagents to successfully knockdown both reporter and endogenous transcripts in Drosophila cells. As toxicity issues have been reported with high level of Cas13, we effectively decreased PspCas13b expression without impairing its function by tuning down translation. Furthermore, we altered the spatial activity of both PspCas13b and RfxCas13d by introducing Nuclear Exportation Sequences (NES) and Nuclear Localization Sequences (NLS) while maintaining activity. Finally, we generated a stable cell line expressing RfxCas13d under the inducible metallothionein promoter, establishing a useful tool for high-throughput genetic screening. Thus, we report new reagents for performing RNA CRISPR-Cas13 experiments in Drosophila, providing additional Cas13 expression constructs that retain activity.
J. A. Bosch, G. Birchak, and N. Perrimon. 2021. “Precise genome engineering in Drosophila using prime editing.” Proc Natl Acad Sci U S A, 118.Abstract
Precise genome editing is a valuable tool to study gene function in model organisms. Prime editing, a precise editing system developed in mammalian cells, does not require double-strand breaks or donor DNA and has low off-target effects. Here, we applied prime editing for the model organism Drosophila melanogaster and developed conditions for optimal editing. By expressing prime editing components in cultured cells or somatic cells of transgenic flies, we precisely introduce premature stop codons in three classical visible marker genes, ebony, white, and forked Furthermore, by restricting editing to germ cells, we demonstrate efficient germ-line transmission of a precise edit in ebony to 36% of progeny. Our results suggest that prime editing is a useful system in Drosophila to study gene function, such as engineering precise point mutations, deletions, or epitope tags.
Baolong Xia, Gabriel Amador, Raghuvir Viswanatha, Jonathan Zirin, Stephanie E Mohr, and Norbert Perrimon. 2020. “CRISPR-based engineering of gene knockout cells by homology-directed insertion in polyploid Drosophila S2R+ cells.” Nat Protoc, 15, 10, Pp. 3478-3498.Abstract
Precise and efficient genome modifications provide powerful tools for biological studies. Previous CRISPR gene knockout methods in cell lines have relied on frameshifts caused by stochastic insertion/deletion in all alleles. However, this method is inefficient for genes with high copy number due to polyploidy or gene amplification because frameshifts in all alleles can be difficult to generate and detect. Here we describe a homology-directed insertion method to knockout genes in the polyploid Drosophila S2R+ cell line. This protocol allows generation of homozygous mutant cell lines using an insertion cassette which autocatalytically generates insertion mutations in all alleles. Knockout cells generated using this method can be directly identified by PCR without a need for DNA sequencing. This protocol takes 2-3 months and can be applied to other polyploid cell lines or high-copy-number genes.
Justin A Bosch, Shannon Knight, Oguz Kanca, Jonathan Zirin, Donghui Yang-Zhou, Yanhui Hu, Jonathan Rodiger, Gabriel Amador, Hugo J Bellen, Norbert Perrimon, and Stephanie E Mohr. 2020. “Use of the CRISPR-Cas9 System in Drosophila Cultured Cells to Introduce Fluorescent Tags into Endogenous Genes.” Curr Protoc Mol Biol, 130, 1, Pp. e112.Abstract
The CRISPR-Cas9 system makes it possible to cause double-strand breaks in specific regions, inducing repair. In the presence of a donor construct, repair can involve insertion or 'knock-in' of an exogenous cassette. One common application of knock-in technology is to generate cell lines expressing fluorescently tagged endogenous proteins. The standard approach relies on production of a donor plasmid with ∼500 to 1000 bp of homology on either side of an insertion cassette that contains the fluorescent protein open reading frame (ORF). We present two alternative methods for knock-in of fluorescent protein ORFs into Cas9-expressing Drosophila S2R+ cultured cells, the single-stranded DNA (ssDNA) Drop-In method and the CRISPaint universal donor method. Both methods eliminate the need to clone a large plasmid donor for each target. We discuss the advantages and limitations of the standard, ssDNA Drop-In, and CRISPaint methods for fluorescent protein tagging in Drosophila cultured cells. © 2019 by John Wiley & Sons, Inc. Basic Protocol 1: Knock-in into Cas9-positive S2R+ cells using the ssDNA Drop-In approach Basic Protocol 2: Knock-in into Cas9-positive S2R+ cells by homology-independent insertion of universal donor plasmids that provide mNeonGreen (CRISPaint method) Support Protocol 1: sgRNA design and cloning Support Protocol 2: ssDNA donor synthesis Support Protocol 3: Transfection using Effectene Support Protocol 4: Electroporation of S2R+-MT::Cas9 Drosophila cells Support Protocol 5: Single-cell isolation of fluorescent cells using FACS.
Raghuvir Viswanatha, Roderick Brathwaite, Yanhui Hu, Zhongchi Li, Jonathan Rodiger, Pierre Merckaert, Verena Chung, Stephanie E Mohr, and Norbert Perrimon. 2019. “Pooled CRISPR Screens in Drosophila Cells.” Curr Protoc Mol Biol, 129, 1, Pp. e111.Abstract
High-throughput screens in Drosophila melanogaster cell lines have led to discovery of conserved gene functions related to signal transduction, host-pathogen interactions, ion transport, and more. CRISPR/Cas9 technology has opened the door to new types of large-scale cell-based screens. Whereas array-format screens require liquid handling automation and assay miniaturization, pooled-format screens, in which reagents are introduced at random and in bulk, can be done in a standard lab setting. We provide a detailed protocol for conducting and evaluating genome-wide CRISPR single guide RNA (sgRNA) pooled screens in Drosophila S2R+ cultured cells. Specifically, we provide step-by-step instructions for library design and production, optimization of cytotoxin-based selection assays, genome-scale screening, and data analysis. This type of project takes ∼3 months to complete. Results can be used in follow-up studies performed in vivo in Drosophila, mammalian cells, and/or other systems. © 2019 by John Wiley & Sons, Inc. Basic Protocol: Pooled-format screening with Cas9-expressing Drosophila S2R+ cells in the presence of cytotoxin Support Protocol 1: Optimization of cytotoxin concentration for Drosophila cell screening Support Protocol 2: CRISPR sgRNA library design and production for Drosophila cell screening Support Protocol 3: Barcode deconvolution and analysis of screening data.
Oguz Kanca, Jonathan Zirin, Jorge Garcia-Marques, Shannon Marie Knight, Donghui Yang-Zhou, Gabriel Amador, Hyunglok Chung, Zhongyuan Zuo, Liwen Ma, Yuchun He, Wen-Wen Lin, Ying Fang, Ming Ge, Shinya Yamamoto, Karen L Schulze, Yanhui Hu, Allan C Spradling, Stephanie E Mohr, Norbert Perrimon, and Hugo J Bellen. 2019. “An efficient CRISPR-based strategy to insert small and large fragments of DNA using short homology arms.” Elife, 8.Abstract
elife-51539-v2.pdf
We previously reported a CRISPR-mediated knock-in strategy into introns of genes, generating an - transgenic library for multiple uses (Lee et al., 2018b). The method relied on double stranded DNA (dsDNA) homology donors with ~1 kb homology arms. Here, we describe three new simpler ways to edit genes in flies. We create single stranded DNA (ssDNA) donors using PCR and add 100 nt of homology on each side of an integration cassette, followed by enzymatic removal of one strand. Using this method, we generated GFP-tagged proteins that mark organelles in S2 cells. We then describe two dsDNA methods using cheap synthesized donors flanked by 100 nt homology arms and gRNA target sites cloned into a plasmid. Upon injection, donor DNA (1 to 5 kb) is released from the plasmid by Cas9. The cassette integrates efficiently and precisely . The approach is fast, cheap, and scalable.
Naoki Okamoto, Raghuvir Viswanatha, Riyan Bittar, Zhongchi Li, Sachiko Haga-Yamanaka, Norbert Perrimon, and Naoki Yamanaka. 2018. “A Membrane Transporter Is Required for Steroid Hormone Uptake in Drosophila.” Dev Cell, 47, 3, Pp. 294-305.e7.Abstract
Steroid hormones are a group of lipophilic hormones that are believed to enter cells by simple diffusion to regulate diverse physiological processes through intracellular nuclear receptors. Here, we challenge this model in Drosophila by demonstrating that Ecdysone Importer (EcI), a membrane transporter identified from two independent genetic screens, is involved in cellular uptake of the steroid hormone ecdysone. EcI encodes an organic anion transporting polypeptide of the evolutionarily conserved solute carrier organic anion superfamily. In vivo, EcI loss of function causes phenotypes indistinguishable from ecdysone- or ecdysone receptor (EcR)-deficient animals, and EcI knockdown inhibits cellular uptake of ecdysone. Furthermore, EcI regulates ecdysone signaling in a cell-autonomous manner and is both necessary and sufficient for inducing ecdysone-dependent gene expression in culture cells expressing EcR. Altogether, our results challenge the simple diffusion model for cellular uptake of ecdysone and may have wide implications for basic and medical aspects of steroid hormone studies.
Ben Ewen-Campen, Stephanie E Mohr, Yanhui Hu, and Norbert Perrimon. 10/9/2017. “Accessing the Phenotype Gap: Enabling Systematic Investigation of Paralog Functional Complexity with CRISPR.” Dev Cell, 43, 1, Pp. 6-9.Abstract
Single-gene knockout experiments can fail to reveal function in the context of redundancy, which is frequently observed among duplicated genes (paralogs) with overlapping functions. We discuss the complexity associated with studying paralogs and outline how recent advances in CRISPR will help address the "phenotype gap" and impact biomedical research.
Huajin Wang, Michel Becuwe, Benjamin E Housden, Chandramohan Chitraju, Ashley J Porras, Morven M Graham, Xinran N Liu, Abdou Rachid Thiam, David B Savage, Anil K Agarwal, Abhimanyu Garg, Maria-Jesus Olarte, Qingqing Lin, Florian Fröhlich, Hans Kristian Hannibal-Bach, Srigokul Upadhyayula, Norbert Perrimon, Tomas Kirchhausen, Christer S Ejsing, Tobias C Walther, and Robert V Farese. 2016. “Seipin is required for converting nascent to mature lipid droplets.” Elife, 5.Abstract

How proteins control the biogenesis of cellular lipid droplets (LDs) is poorly understood. Using Drosophila and human cells, we show here that seipin, an ER protein implicated in LD biology, mediates a discrete step in LD formation-the conversion of small, nascent LDs to larger, mature LDs. Seipin forms discrete and dynamic foci in the ER that interact with nascent LDs to enable their growth. In the absence of seipin, numerous small, nascent LDs accumulate near the ER and most often fail to grow. Those that do grow prematurely acquire lipid synthesis enzymes and undergo expansion, eventually leading to the giant LDs characteristic of seipin deficiency. Our studies identify a discrete step of LD formation, namely the conversion of nascent LDs to mature LDs, and define a molecular role for seipin in this process, most likely by acting at ER-LD contact sites to enable lipid transfer to nascent LDs.

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