title: In Vivo Transcriptional Activation Using CRISPR/Cas9 in Drosophila.
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.
authors.affiliation: Tsinghua-Peking-National Institute of Biological Sciences Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing 100084, China Department of Genetics.
authors.forename: Shuailiang
authors.initials: S
authors.lastname: Lin
authors.affiliation: Department of Genetics bewencampen@genetics.med.harvard.edu perrimon@receptor.med.harvard.edu.
authors.forename: Ben
authors.initials: B
authors.lastname: Ewen-Campen
authors.affiliation: Department of Genetics.
authors.forename: Xiaochun
authors.initials: X
authors.lastname: Ni
authors.affiliation: Department of Genetics.
authors.forename: Benjamin E
authors.initials: BE
authors.lastname: Housden
authors.affiliation: Department of Genetics Howard Hughes Medical Institute, Harvard Medical School, Boston, Massachusetts 02115 bewencampen@genetics.med.harvard.edu perrimon@receptor.med.harvard.edu.
authors.forename: Norbert
authors.initials: N
authors.lastname: Perrimon
mesh_terms: D000818:Animals; D064113:CRISPR-Cas Systems / Q000235:genetics*; D004330:Drosophila / Q000235:genetics / Q000254:growth & development; D029721:Drosophila Proteins / Q000096:biosynthesis / Q000235:genetics*; D018507:Gene Expression Regulation, Developmental; D006801:Humans; D008648:Mesoderm / Q000254:growth & development; D000094704:RNA, Guide, CRISPR-Cas Systems / Q000235:genetics; D000071250:Snail Family Transcription Factors; D014157:Transcription Factors / Q000096:biosynthesis / Q000235:genetics*; D015533:Transcriptional Activation / Q000235:genetics*; D051879:Twist-Related Protein 1 / Q000096:biosynthesis / Q000235:genetics*
chemical_list: D029721:Drosophila Proteins; D000094704:RNA, Guide, CRISPR-Cas Systems; D000071250:Snail Family Transcription Factors; D014157:Transcription Factors; C497753:Twi protein, Drosophila; D051879:Twist-Related Protein 1; C000604451:sna protein, Drosophila
keywords: CRISPR-Cas9; gene activation; overexpression, gain-of-function