Cell-based assays

Regardless of the technology (RNAi, CRISPR, over-expression, etc.), a good cell-based assay is the best foundation for a cell-based screen. We have equipment, provide reagents, share protocols, and more to support development of high-throughput screen assays in Drosophila cells.

Reagents, consultation, and other support is available for screens off-site. We also support screens on-site at our facility. Assays can be done using a number of types of reagents, including reagents for knockdown or over-expression of protein-coding genes, and interrogation of miRNAs.

See links below to relevant reagents, protocols, publications, and more.


Graphical image of tissue culture, fly pushing, and computer, and the team of people who work with them

DRSC/TRiP and DRSC-BTRR Office Hours

September 13, 2021

New this fall: Online office hours!

Do you have questions about modifying Drosophila cell lines with CRISPR or performing large-scale cell screens? Questions about in vivo RNAi with TRiP fly stocks or CRISPR knockout or activation with our sgRNA fly stocks? Questions about our new protocols and resources for CRISPR mosquito cell lines? Pop into our Zoom office hours to say hello and get our expert input! Registration is required (see below).

DRSC/TRiP & DRSC-BTRR Office Hours Schedule:

Mon. Sept. 27, 2021, 12...

Read more about DRSC/TRiP and DRSC-BTRR Office Hours
Graphical image of tissue culture, fly pushing, and computer, and the team of people who work with them

DRSC-Biomedical Technology Research Resource

October 21, 2019

We are pleased to announce that we have been funded by NIH NIGMS to form the Drosophila Research & Screening Center-Biomedical Technology Research Resource (DRSC-BTRR). The P41-funded DRSC-BTRR (N. Perrimon, PI; S. Mohr, Co-I) builds upon and extends past goals of the Drosophila RNAi Screening Center.

As the DRSC-BTRR, we are working together with collaborators whose 'driving biomedical projects' inform development of new technologies at the DRSC. At the same time, we continue to support Drosophila cell-based RNAi and CRIPSR knockout screens and related...

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Photo of 384-well assay plates

Drosophila cell screen with DRSC reagent library contributes to identification of new therapeutic target for renal cancer

October 7, 2019

We here at the DRSC/TRiP are thrilled to see this study from Hilary Nicholson et al. published in Science Signaling.

The study provides a great example of how screens in Drosophila cultured cells can be used as part of a cross-species platform aimed at discovery of new targets for disease treatment. The work represents a collaboration between the laboratory of 2019 Nobel Prize winner W. Kaelin and DRSC PI N. Perrimon.


Read more about Drosophila cell screen with DRSC reagent library contributes to identification of new therapeutic target for renal cancer
Cartoon of fly host cells with virus or endosymbiotic bacteria

Cell-based RNAi screening helps reveal host-microbe interactions--two new screen reports

November 19, 2018

Laboratories at the Skirball Institute at New York University and the Boyce Thompson Institute at Cornell University reported results of two different cell-based Drosophila RNAi screens in papers published this week. The screens have in common that they looked at interactions between the host insect cells and a microbe -- the endosymbiont Wolbachia in one study and baculovirus in the other. For more, check out the newly published studies. For both these screens, the DRSC provided libraries for screens that were then performed at the host institution.


... Read more about Cell-based RNAi screening helps reveal host-microbe interactions--two new screen reports

Missed us at ADRC 2018? View our workshop slides!

April 19, 2018
Thank you to all those who attended our workshop at last week's Annual Drosophila Research Conference in Philadelphia, PA, USA. It was great to talk fly stocks, cell screens, and bioinformatics with the community. We are here to help and look forward to continued feedback on the resources we are building to empower your research. PDFs of our workshop presentations are attached to this news item. The slides will help you learn more about our in vivo resources for CRISPR, new pooled cell-based CRISPR screen technology, and bioinformatics resources at our facility.  Feel free to contact... Read more about Missed us at ADRC 2018? View our workshop slides!
Cartoon of essential gene pooled screen (made using BioRender.io)

Pooled-format CRISPR screens in Drosophila cells

March 22, 2018

The DRSC/TRiP-FGR is pleased to support collaborations on pooled CRISPR screens using the method recently, reported in eLife by Viswanatha et al. (PDF download file below).

From the abstract: "... Here, we developed a site-specific integration strategy for library delivery and performed a genome-wide CRISPR knockout screen in Drosophila S2R+ cells. Under basal growth conditions, 1235 genes were essential for cell fitness...

Read more about Pooled-format CRISPR screens in Drosophila cells

Contact Us

Please contact us for any questions.


Jiunn Song, Arda Mizrak, Chia-Wei Lee, Marcelo Cicconet, Zon Weng Lai, Chieh-Han Lu, Stephanie E. Mohr, Jr Robert V. Farese, and Tobias C. Walther. 9/15/2021. “Identification of two pathways mediating protein targeting from ER to lipid droplets”. Publisher's VersionAbstract
Pathways localizing proteins to their sites of action within a cell are essential for eukaryotic cell organization and function. Although mechanisms of protein targeting to many organelles have been defined, little is known about how proteins, such as key metabolic enzymes, target from the ER to cellular lipid droplets (LDs). Here, we identify two distinct pathways for ER-to-LD (ERTOLD) protein targeting: early ERTOLD, occurring during LD formation, and late ERTOLD, targeting mature LDs after their formation. By using systematic, unbiased approaches, we identified specific membrane-fusion machinery, including regulators, a tether, and SNARE proteins, that are required for late ERTOLD targeting. Components of this fusion machinery localize to LD-ER interfaces and appear to be organized at ER exit sites (ERES) to generate ER-LD membrane bridges. We also identified multiple cargoes for early and late ERTOLD. Collectively, our data provide a new model for how proteins target LDs from the ER.
Xiangzhao Yue, Yongkang Liang, Zhishuang Wei, Jun Lv, Yongjin Cai, Xiaobin Fan, Wenqing Zhang, and Jie Chen. 2021. “Genome-wide in vitro and in vivo RNAi screens reveal Fer3 to be an important regulator of kkv transcription in Drosophila.” Insect Sci.Abstract
Krotzkopf verkehrt (kkv) is a key enzyme that catalyzes the synthesis of chitin, an important component of the Drosophila epidermis, trachea, and other tissues. Here, we report the use of comprehensive RNA interference (RNAi) analyses to search for kkv transcriptional regulators. A cell-based RNAi screen identified 537 candidate kkv regulators on a genome-wide scale. Subsequent use of transgenic Drosophila lines expressing RNAi constructs enabled in vivo validation, and we identified six genes as potential kkv transcriptional regulators. Weakening of the kkvDsRed signal, an in vivo reporter indicating kkv promoter activity, was observed when the expression of Akirin, NFAT, 48 related 3 (Fer3), or Autophagy-related 101(Atg101) was knocked down in Drosophila at the 3rd-instar larval stage; whereas we observed disoriented taenidial folds on larval tracheae when Lines (lin) or Autophagy-related 3(Atg3) was knocked down in the tracheae. Fer3, in particular, has been shown to be an important factor in the activation of kkv transcription via specific binding with the kkv promoter. The genes involved in the chitin synthesis pathway were widely affected by the downregulation of Fer3. Furthermore, Atg101, Atg3, Akirin, Lin, NFAT, Pnr and Abd-A showed the potential complex mechanism of kkv transcription are regulated by an interaction network with bithorax complex components. Our study revealed the hitherto unappreciated diversity of modulators impinging on kkv transcription and opens new avenues in the study of kkv regulation and chitin biosynthesis. This article is protected by copyright. All rights reserved.
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.
Hilary E Nicholson, Zeshan Tariq, Benjamin E Housden, Rebecca B Jennings, Laura A Stransky, Norbert Perrimon, Sabina Signoretti, and William G Kaelin. 2019. “HIF-independent synthetic lethality between CDK4/6 inhibition and VHL loss across species.” Sci Signal, 12, 601.Abstract
Inactivation of the tumor suppressor gene is the signature initiating event in clear cell renal cell carcinoma (ccRCC), the most common form of kidney cancer, and causes the accumulation of hypoxia-inducible factor 2α (HIF-2α). HIF-2α inhibitors are effective in some ccRCC cases, but both de novo and acquired resistance have been observed in the laboratory and in the clinic. Here, we identified synthetic lethality between decreased activity of cyclin-dependent kinases 4 and 6 (CDK4/6) and inactivation in two species (human and ) and across diverse human ccRCC cell lines in culture and xenografts. Although HIF-2α transcriptionally induced the CDK4/6 partner cyclin D1, HIF-2α was not required for the increased CDK4/6 requirement of ccRCC cells. Accordingly, the antiproliferative effects of CDK4/6 inhibition were synergistic with HIF-2α inhibition in HIF-2α-dependent ccRCC cells and not antagonistic with HIF-2α inhibition in HIF-2α-independent cells. These findings support testing CDK4/6 inhibitors as treatments for ccRCC, alone and in combination with HIF-2α inhibitors.
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