Method or protocol

Working Paper
R. Viswanatha, M. Zaffagni, J. Zirin, N. Perrimon, and S. Kadener. Working Paper. “CRISPR-Cas13 mediated Knock Down in Drosophila cultured cells.” BioRxiv.Abstract
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.
2020.11.01.364166v1.full_.pdf
Jun Xu, Ah-Ram Kim, Ross W. Cheloha, Fabian A. Fischer, Joshua Shing Shun Li, Yuan Feng, Emily Stoneburner, Richard Binari, Stephanie E. Mohr, Jonathan Zirin, Hidde Ploegh, and Norbert Perrimon. Working Paper. “Protein visualization and manipulation in Drosophila through the use of epitope tags recognized by nanobodies.” bioRxiv.Abstract
Expansion of the available repertoire of reagents for visualization and manipulation of proteins will help understand their function. Short epitope tags installed on proteins of interest and recognized by existing binders such as nanobodies facilitate protein studies by obviating the need to isolate new antibodies directed against them. Nanobodies have several advantages over conventional antibodies, as they can be expressed and used as tools for visualization and manipulation of proteins in vivo. Here, we combine the advantages of short epitopes (NanoTags) and nanobodies specific for them by characterizing two short (<15 aa) tags, 127D01 and VHH05, which are high-affinity targets of nanobodies. We demonstrate that these NanoTags and the nanobodies that recognize them can be used in Drosophila for in vivo protein detection and re-localization, direct and indirect immunofluorescence, immunoblotting, and immunoprecipitation. We further show that CRISPR-mediated gene targeting provides a straightforward approach to tagging endogenous proteins with the NanoTags. Single copies of the NanoTags, regardless of their location, suffice for detection. This versatile and validated toolbox of tags and nanobodies will serve as a resource for a wide array of applications, including functional studies in Drosophila and beyond.Competing Interest StatementThe authors have declared no competing interest.
2021.04.16.440240v1.full_.pdf
2021
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.
2020
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.
Jonathan Zirin, Yanhui Hu, Luping Liu, Donghui Yang-Zhou, Ryan Colbeth, Dong Yan, Ben Ewen-Campen, Rong Tao, Eric Vogt, Sara VanNest, Cooper Cavers, Christians Villalta, Aram Comjean, Jin Sun, Xia Wang, Yu Jia, Ruibao Zhu, Ping Peng, Jinchao Yu, Da Shen, Yuhao Qiu, Limmond Ayisi, Henna Ragoowansi, Ethan Fenton, Senait Efrem, Annette Parks, Kuniaki Saito, Shu Kondo, Liz Perkins, Stephanie E Mohr, Jianquan Ni, and Norbert Perrimon. 2020. “Large-Scale Transgenic Resource Collections for Loss- and Gain-of-Function Studies.” Genetics.Abstract
The Transgenic RNAi Project (TRiP), a functional genomics platform at Harvard Medical School, was initiated in 2008 to generate and distribute a genome-scale collection of RNAi fly stocks. To date, the TRiP has generated >15,000 RNAi fly stocks. As this covers most genes, we have largely transitioned to development of new resources based on CRISPR technology. Here, we present an update on our libraries of publicly available RNAi and CRISPR fly stocks, and focus on the TRiP-CRISPR overexpression (TRiP-OE) and TRiP-CRISPR knockout (TRiP-KO) collections. TRiP-OE stocks express sgRNAs targeting upstream of a gene transcription start site. Gene activation is triggered by co-expression of catalytically dead Cas9 (dCas9) fused to an activator domain, either VP64-p65-Rta (VPR) or Synergistic Activation Mediator (SAM). TRiP-KO stocks express one or two sgRNAs targeting the coding sequence of a gene or genes. Cutting is triggered by co-expression of Cas9, allowing for generation of indels in both germline and somatic tissue. To date, we have generated more than 5,000 CRISPR-OE or -KO stocks for the community. These resources provide versatile, transformative tools for gene activation, gene repression, and genome engineering.
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.
2019
Justin A. Bosch, Ryan Colbeth, Jonathan Zirin, and Norbert Perrimon. 5/16/2019. “Gene knock-ins in Drosophila using homology-independent insertion of universal donor plasmids.” BioRxiv. Publisher's Version 2019_BioRxiv_Bosch .pdf
Spencer E. Escobedo, Jonathan Zirin, and Vikki M. Weake. 4/4/2019. “TRiP stocks contain a previously uncharacterized loss-of-function sevenless allele.” microPublication Biology. Publisher's Version escobedotripsev_lof_2019_final.pdf
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.
2016
Chen X and Xu L. 2016. “Genome-Wide RNAi Screening to Dissect the TGF-β Signal Transduction Pathway.” Methods in Molecular Biology. Publisher's VersionAbstract

The transforming growth factor-β (TGF-β) family of cytokines figures prominently in regulation of embryonic development and adult tissue homeostasis from Drosophila to mammals. Genetic defects affecting TGF-β signaling underlie developmental disorders and diseases such as cancer in human. Therefore, delineating the molecular mechanism by which TGF-β regulates cell biology is critical for understanding normal biology and disease mechanisms. Forward genetic screens in model organisms and biochemical approaches in mammalian tissue culture were instrumental in initial characterization of the TGF-β signal transduction pathway. With complete sequence information of the genomes and the advent of RNA interference (RNAi) technology, genome-wide RNAi screening emerged as a powerful functional genomics approach to systematically delineate molecular components of signal transduction pathways. Here, we describe a protocol for image-based whole-genome RNAi screening aimed at identifying molecules required for TGF-β signaling into the nucleus. Using this protocol we examined >90 % of annotated Drosophila open reading frames (ORF) individually and successfully uncovered several novel factors serving critical roles in the TGF-β pathway. Thus cell-based high-throughput functional genomics can uncover new mechanistic insights on signaling pathways beyond what the classical genetics had revealed.

2015
Shuailiang Lin, Ben Ewen-Campen, Xiaochun Ni, Benjamin E Housden, and Norbert Perrimon. 2015. “In Vivo Transcriptional Activation Using CRISPR/Cas9 in Drosophila.” Genetics, 201, 2, Pp. 433-42.Abstract

A number of approaches for Cas9-mediated transcriptional activation have recently been developed, allowing target genes to be overexpressed from their endogenous genomic loci. However, these approaches have thus far been limited to cell culture, and this technique has not been demonstrated in vivo in any animal. The technique involving the fewest separate components, and therefore the most amenable to in vivo applications, is the dCas9-VPR system, where a nuclease-dead Cas9 is fused to a highly active chimeric activator domain. In this study, we characterize the dCas9-VPR system in Drosophila cells and in vivo. We show that this system can be used in cell culture to upregulate a range of target genes, singly and in multiplex, and that a single guide RNA upstream of the transcription start site can activate high levels of target transcription. We observe marked heterogeneity in guide RNA efficacy for any given gene, and we confirm that transcription is inhibited by guide RNAs binding downstream of the transcription start site. To demonstrate one application of this technique in cells, we used dCas9-VPR to identify target genes for Twist and Snail, two highly conserved transcription factors that cooperate during Drosophila mesoderm development. In addition, we simultaneously activated both Twist and Snail to identify synergistic responses to this physiologically relevant combination. Finally, we show that dCas9-VPR can activate target genes and cause dominant phenotypes in vivo, providing the first demonstration of dCas9 activation in a multicellular animal. Transcriptional activation using dCas9-VPR thus offers a simple and broadly applicable technique for a variety of overexpression studies.

2015_Genetics_Lin.pdf Supplement.pdf Corrigendum.pdf
Stephanie E Mohr, Yanhui Hu, Kirstin Rudd, Michael Buckner, Quentin Gilly, Blake Foster, Katarzyna Sierzputowska, Aram Comjean, Bing Ye, and Norbert Perrimon. 2015. “Reagent and Data Resources for Investigation of RNA Binding Protein Functions in Drosophila melanogaster Cultured Cells.” G3 (Bethesda), 5, 9, Pp. 1919-24.Abstract

RNA binding proteins (RBPs) are involved in many cellular functions. To facilitate functional characterization of RBPs, we generated an RNA interference (RNAi) library for Drosophila cell-based screens comprising reagents targeting known or putative RBPs. To test the quality of the library and provide a baseline analysis of the effects of the RNAi reagents on viability, we screened the library using a total ATP assay and high-throughput imaging in Drosophila S2R+ cultured cells. The results are consistent with production of a high-quality library that will be useful for functional genomics studies using other assays. Altogether, we provide resources in the form of an initial curated list of Drosophila RBPs; an RNAi screening library we expect to be used with additional assays that address more specific biological questions; and total ATP and image data useful for comparison of those additional assay results with fundamental information such as effects of a given reagent in the library on cell viability. Importantly, we make the baseline data, including more than 200,000 images, easily accessible online.

2015_G3_Mohr.pdf Reagent Table S1.xlsx
Lizabeth A Perkins, Laura Holderbaum, Rong Tao, Yanhui Hu, Richelle Sopko, Kim McCall, Donghui Yang-Zhou, Ian Flockhart, Richard Binari, Hye-Seok Shim, Audrey Miller, Amy Housden, Marianna Foos, Sakara Randkelv, Colleen Kelley, Pema Namgyal, Christians Villalta, Lu-Ping Liu, Xia Jiang, Qiao Huan-Huan, Xia Wang, Asao Fujiyama, Atsushi Toyoda, Kathleen Ayers, Allison Blum, Benjamin Czech, Ralph Neumuller, Dong Yan, Amanda Cavallaro, Karen Hibbard, Don Hall, Lynn Cooley, Gregory J Hannon, Ruth Lehmann, Annette Parks, Stephanie E Mohr, Ryu Ueda, Shu Kondo, Jian-Quan Ni, and Norbert Perrimon. 2015. “The Transgenic RNAi Project at Harvard Medical School: Resources and Validation.” Genetics, 201, 3, Pp. 843-52.Abstract

To facilitate large-scale functional studies in Drosophila, the Drosophila Transgenic RNAi Project (TRiP) at Harvard Medical School (HMS) was established along with several goals: developing efficient vectors for RNAi that work in all tissues, generating a genome-scale collection of RNAi stocks with input from the community, distributing the lines as they are generated through existing stock centers, validating as many lines as possible using RT-qPCR and phenotypic analyses, and developing tools and web resources for identifying RNAi lines and retrieving existing information on their quality. With these goals in mind, here we describe in detail the various tools we developed and the status of the collection, which is currently composed of 11,491 lines and covering 71% of Drosophila genes. Data on the characterization of the lines either by RT-qPCR or phenotype is available on a dedicated website, the RNAi Stock Validation and Phenotypes Project (RSVP, http://www.flyrnai.org/RSVP.html), and stocks are available from three stock centers, the Bloomington Drosophila Stock Center (United States), National Institute of Genetics (Japan), and TsingHua Fly Center (China).

2015_Genetics_Perkins.pdf Supplement.pdf
2014
Benjamin E Housden, Shuailiang Lin, and Norbert Perrimon. 2014. “Cas9-based genome editing in Drosophila.” Methods Enzymol, 546, Pp. 415-39.Abstract

Our ability to modify the Drosophila genome has recently been revolutionized by the development of the CRISPR system. The simplicity and high efficiency of this system allows its widespread use for many different applications, greatly increasing the range of genome modification experiments that can be performed. Here, we first discuss some general design principles for genome engineering experiments in Drosophila and then present detailed protocols for the production of CRISPR reagents and screening strategies to detect successful genome modification events in both tissue culture cells and animals.

2014_Methods Enzymol_Housden.pdf
Arunachalam Vinayagam, Jonathan Zirin, Charles Roesel, Yanhui Hu, Bahar Yilmazel, Anastasia A Samsonova, Ralph A Neumüller, Stephanie E Mohr, and Norbert Perrimon. 2014. “Integrating protein-protein interaction networks with phenotypes reveals signs of interactions.” Nat Methods, 11, 1, Pp. 94-9.Abstract

A major objective of systems biology is to organize molecular interactions as networks and to characterize information flow within networks. We describe a computational framework to integrate protein-protein interaction (PPI) networks and genetic screens to predict the 'signs' of interactions (i.e., activation-inhibition relationships). We constructed a Drosophila melanogaster signed PPI network consisting of 6,125 signed PPIs connecting 3,352 proteins that can be used to identify positive and negative regulators of signaling pathways and protein complexes. We identified an unexpected role for the metabolic enzymes enolase and aldo-keto reductase as positive and negative regulators of proteolysis, respectively. Characterization of the activation-inhibition relationships between physically interacting proteins within signaling pathways will affect our understanding of many biological functions, including signal transduction and mechanisms of disease.

2014_Nat Methods_Vinayagam.pdf Supplemental Files.zip
Bahar Yilmazel, Yanhui Hu, Frederic Sigoillot, Jennifer A Smith, Caroline E Shamu, Norbert Perrimon, and Stephanie E Mohr. 2014. “Online GESS: prediction of miRNA-like off-target effects in large-scale RNAi screen data by seed region analysis.” BMC Bioinformatics, 15, Pp. 192.Abstract

BACKGROUND: RNA interference (RNAi) is an effective and important tool used to study gene function. For large-scale screens, RNAi is used to systematically down-regulate genes of interest and analyze their roles in a biological process. However, RNAi is associated with off-target effects (OTEs), including microRNA (miRNA)-like OTEs. The contribution of reagent-specific OTEs to RNAi screen data sets can be significant. In addition, the post-screen validation process is time and labor intensive. Thus, the availability of robust approaches to identify candidate off-targeted transcripts would be beneficial. RESULTS: Significant efforts have been made to eliminate false positive results attributable to sequence-specific OTEs associated with RNAi. These approaches have included improved algorithms for RNAi reagent design, incorporation of chemical modifications into siRNAs, and the use of various bioinformatics strategies to identify possible OTEs in screen results. Genome-wide Enrichment of Seed Sequence matches (GESS) was developed to identify potential off-targeted transcripts in large-scale screen data by seed-region analysis. Here, we introduce a user-friendly web application that provides researchers a relatively quick and easy way to perform GESS analysis on data from human or mouse cell-based screens using short interfering RNAs (siRNAs) or short hairpin RNAs (shRNAs), as well as for Drosophila screens using shRNAs. Online GESS relies on up-to-date transcript sequence annotations for human and mouse genes extracted from NCBI Reference Sequence (RefSeq) and Drosophila genes from FlyBase. The tool also accommodates analysis with user-provided reference sequence files. CONCLUSION: Online GESS provides a straightforward user interface for genome-wide seed region analysis for human, mouse and Drosophila RNAi screen data. With the tool, users can either use a built-in database or provide a database of transcripts for analysis. This makes it possible to analyze RNAi data from any organism for which the user can provide transcript sequences.

2014_BMC Bioinfo_Yilmazel.pdf
2013
Clément Carré, Caroline Jacquier, Anne-Laure Bougé, Fabrice de Chaumont, Corinne Besnard-Guerin, Hélène Thomassin, Josette Pidoux, Bruno Da Silva, Eleftheria Chalatsi, Sarah Zahra, Jean-Christophe Olivo-Marin, Hélène Munier-Lehmann, and Christophe Antoniewski. 2013. “AutomiG, a biosensor to detect alterations in miRNA biogenesis and in small RNA silencing guided by perfect target complementarity.” PLoS One, 8, 9, Pp. e74296.Abstract

Defects in miRNA biogenesis or activity are associated to development abnormalities and diseases. In Drosophila, miRNAs are predominantly loaded in Argonaute-1, which they guide for silencing of target RNAs. The miRNA pathway overlaps the RNAi pathway in this organism, as miRNAs may also associate with Argonaute-2, the mediator of RNAi. We set up a gene construct in which a single inducible promoter directs the expression of the GFP protein as well as two miRNAs perfectly matching the GFP sequences. We show that self-silencing of the resulting automiG gene requires Drosha, Pasha, Dicer-1, Dicer-2 and Argonaute-2 loaded with the anti-GFP miRNAs. In contrast, self-silencing of the automiG gene does not involve Argonaute-1. Thus, automiG reports in vivo for both miRNA biogenesis and Ago-2 mediated silencing, providing a powerful biosensor to identify situations where miRNA or siRNA pathways are impaired. As a proof of concept, we used automiG as a biosensor to screen a chemical library and identified 29 molecules that strongly inhibit miRNA silencing, out of which 5 also inhibit RNAi triggered by long double-stranded RNA. Finally, the automiG sensor is also self-silenced by the anti-GFP miRNAs in HeLa cells and might be easily used to identify factors involved in miRNA biogenesis and silencing guided by perfect target complementarity in mammals.

2013_PLOS One_Carre.pdf Supplemental Files.zip
Max V Staller, Dong Yan, Sakara Randklev, Meghan D Bragdon, Zeba B Wunderlich, Rong Tao, Lizabeth A Perkins, Angela H Depace, and Norbert Perrimon. 2013. “Depleting gene activities in early Drosophila embryos with the "maternal-Gal4-shRNA" system.” Genetics, 193, 1, Pp. 51-61.Abstract

In a developing Drosophila melanogaster embryo, mRNAs have a maternal origin, a zygotic origin, or both. During the maternal-zygotic transition, maternal products are degraded and gene expression comes under the control of the zygotic genome. To interrogate the function of mRNAs that are both maternally and zygotically expressed, it is common to examine the embryonic phenotypes derived from female germline mosaics. Recently, the development of RNAi vectors based on short hairpin RNAs (shRNAs) effective during oogenesis has provided an alternative to producing germline clones. Here, we evaluate the efficacies of: (1) maternally loaded shRNAs to knockdown zygotic transcripts and (2) maternally loaded Gal4 protein to drive zygotic shRNA expression. We show that, while Gal4-driven shRNAs in the female germline very effectively generate phenotypes for genes expressed maternally, maternally loaded shRNAs are not very effective at generating phenotypes for early zygotic genes. However, maternally loaded Gal4 protein is very efficient at generating phenotypes for zygotic genes expressed during mid-embryogenesis. We apply this powerful and simple method to unravel the embryonic functions of a number of pleiotropic genes.

2013_Genetics_Staller.pdf Table S1.pdf
Yanhui Hu, Richelle Sopko, Marianna Foos, Colleen Kelley, Ian Flockhart, Noemie Ammeux, Xiaowei Wang, Lizabeth Perkins, Norbert Perrimon, and Stephanie E Mohr. 2013. “FlyPrimerBank: an online database for Drosophila melanogaster gene expression analysis and knockdown evaluation of RNAi reagents.” G3 (Bethesda), 3, 9, Pp. 1607-16.Abstract

The evaluation of specific endogenous transcript levels is important for understanding transcriptional regulation. More specifically, it is useful for independent confirmation of results obtained by the use of microarray analysis or RNA-seq and for evaluating RNA interference (RNAi)-mediated gene knockdown. Designing specific and effective primers for high-quality, moderate-throughput evaluation of transcript levels, i.e., quantitative, real-time PCR (qPCR), is nontrivial. To meet community needs, predefined qPCR primer pairs for mammalian genes have been designed and sequences made available, e.g., via PrimerBank. In this work, we adapted and refined the algorithms used for the mammalian PrimerBank to design 45,417 primer pairs for 13,860 Drosophila melanogaster genes, with three or more primer pairs per gene. We experimentally validated primer pairs for ~300 randomly selected genes expressed in early Drosophila embryos, using SYBR Green-based qPCR and sequence analysis of products derived from conventional PCR. All relevant information, including primer sequences, isoform specificity, spatial transcript targeting, and any available validation results and/or user feedback, is available from an online database (www.flyrnai.org/flyprimerbank). At FlyPrimerBank, researchers can retrieve primer information for fly genes either one gene at a time or in batch mode. Importantly, we included the overlap of each predicted amplified sequence with RNAi reagents from several public resources, making it possible for researchers to choose primers suitable for knockdown evaluation of RNAi reagents (i.e., to avoid amplification of the RNAi reagent itself). We demonstrate the utility of this resource for validation of RNAi reagents in vivo.

2013_G3_Hu.pdf Supplemental Files.zip
Xingjie Ren, Jin Sun, Benjamin E Housden, Yanhui Hu, Charles Roesel, Shuailiang Lin, Lu-Ping Liu, Zhihao Yang, Decai Mao, Lingzhu Sun, Qujie Wu, Jun-Yuan Ji, Jianzhong Xi, Stephanie E Mohr, Jiang Xu, Norbert Perrimon, and Jian-Quan Ni. 2013. “Optimized gene editing technology for Drosophila melanogaster using germ line-specific Cas9.” Proc Natl Acad Sci U S A, 110, 47, Pp. 19012-7.Abstract

The ability to engineer genomes in a specific, systematic, and cost-effective way is critical for functional genomic studies. Recent advances using the CRISPR-associated single-guide RNA system (Cas9/sgRNA) illustrate the potential of this simple system for genome engineering in a number of organisms. Here we report an effective and inexpensive method for genome DNA editing in Drosophila melanogaster whereby plasmid DNAs encoding short sgRNAs under the control of the U6b promoter are injected into transgenic flies in which Cas9 is specifically expressed in the germ line via the nanos promoter. We evaluate the off-targets associated with the method and establish a Web-based resource, along with a searchable, genome-wide database of predicted sgRNAs appropriate for genome engineering in flies. Finally, we discuss the advantages of our method in comparison with other recently published approaches.

2013_PNAS_Ren.pdf Supplement.pdf

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