CRISPR/Cas9 and Genome Editing in Drosophila

Recent advances in our ability to design DNA binding factors with specificity for desired sequences have resulted in a revolution in genetic engineering, enabling directed changes to the genome to be made relatively easily. Traditional techniques for generating genetic mutations in most organisms have relied on selection from large pools of randomly induced mutations for those of particular interest, or time-consuming gene targeting by homologous recombination. Drosophila melanogaster has always been at the forefront of genetic analysis, and application of these new genome editing techniques to this organism will revolutionise our approach to performing analysis of gene function in the future. We discuss the recent techniques that apply the CRISPR/Cas9 system to Drosophila, highlight potential uses for this technology and speculate upon the future of genome engineering in this model organism.     

A simplified and efficient germline-specific CRISPR/Cas9 system for Drosophila genomic engineering

The type II CRISPR/Cas9 system (clustered regularly interspaced short palindromic repeats/CRISPR-associated) has recently emerged as an efficient and simple tool for site-specific engineering of eukaryotic genomes. To improve its applications in Drosophila genome engineering, we simplified the standard two-component CRISPR/Cas9 system by generating a stable transgenic fly line expressing the Cas9 endonuclease in the germline (Vasa-Cas9 line). By injecting vectors expressing engineered target-specific guide RNAs into Vasa-Cas9 fly embryos, mutations were generated from site-specific DNA cleavages and efficiently transmitted into progenies. Because Cas9 endonuclease is the universal component of the type II CRISPR/Cas9 system, site-specific genomic engineering based on this improved platform can be achieved with lower complexity and toxicity, greater consistency, and excellent versatility.     

A simplified and efficient germline-specific CRISPR/Cas9 system for Drosophila genomic engineering

The type II CRISPR/Cas9 system (clustered regularly interspaced short palindromic repeats/CRISPR-associated) has recently emerged as an efficient and simple tool for site-specific engineering of eukaryotic genomes. To improve its applications in Drosophila genome engineering, we simplified the standard two-component CRISPR/Cas9 system by generating a stable transgenic fly line expressing the Cas9 endonuclease in the germline (Vasa-Cas9 line). By injecting vectors expressing engineered target-specific guide RNAs into Vasa-Cas9 fly embryos, mutations were generated from site-specific DNA cleavages and efficiently transmitted into progenies. Because Cas9 endonuclease is the universal component of the type II CRISPR/Cas9 system, site-specific genomic engineering based on this improved platform can be achieved with lower complexity and toxicity, greater consistency, and excellent versatility.     

Functional characterization of SlitPBP3 in Spodoptera litura by CRISPR/Cas9 mediated genome editing

Functional gene analysis by using genome editing techniques is limited only in few model insects. Here, we reported an efficient and heritable gene mutagenesis analysis in an important lepidopteran pest, Spodoptera litura, using the CRISPR/Cas9 system. By using this system, we successfully obtained the homozygous S. litura strain by targeting the pheromone binding protein 3 gene (SlitPBP3), which allowed us to elucidate the role of this gene in the olfaction of the female sex pheromones. By co-injection of Cas9 mRNA and sgRNA into S. litura eggs, highly efficient chimera mutation in SlitPBP3 loci was detected both in injected eggs (39.1%) and in the resulting individual moths (87.5%). We used the mutant moths as parents to obtain the G1 offspring and the homozygous mutant strain in G2. The function of SlitPBP3 was explored by Electroantennogram (EAG) recordings with a homozygous mutant strain. The result showed that the EAG responses were significantly decreased in mutant males than in control males when treated with the major sex pheromone component (Z9,E11-14:Ac) and a minor component (Z9-14:Ac) at higher dosages. The results demonstrate that s SlitPBP3 gene plays a minor role in the perception of the female sex pheromones. Furthermore, our study provides a useful methodology with the CRISPR/Cas9 system for gene in vivo functional study, particular for lepidopteran species in which the RNAi approach is not efficient.     

CRISPR/Cas9-Targeted Mutagenesis in Caenorhabditis elegans

The generation of genetic mutants in Caenorhabditis elegans has long relied on the selection of mutations in large-scale screens. Directed mutagenesis of specific loci in the genome would greatly speed up analysis of gene function. Here, we adapt the CRISPR/Cas9 system to generate mutations at specific sites in the C. elegans genome.     

Functional non-homologous end joining patterns triggered by CRISPR/Cas9 in human cells

正CRISPR/Cas9-mediated genome engineering technologies are now widely applied in various organisms,including mouse and human cells(Cong et al.,2013;Mali et al.,2013;Yang et al.,2013;Hsu et al.,2014).The most widely used customized CRISPR/Cas9(Sp Cas9)is derived from Streptococcus pyogenes(Cong et al.,2013).The CRISPR/Cas9 system creates site-specific double-     

基于CRISPR/Cas9系统对干酪乳杆菌进行红色荧光蛋白标记

本实验利用CRISPR/Cas9系统对干酪乳杆菌(Lactobacillus casei) LC2W进行红色荧光蛋白(red fluorescent protein,RFP)标记,用于研究干酪乳杆菌在肠道内的分布和定植状况,评价其作为益生菌的功能。首先,基于本实验室已有的干酪乳杆菌CRISPR/Cas9编辑质粒pLCNICK-1628构建重组质粒pLCNICK-1628-RFP,电转入干酪乳杆菌LC2W感受态细胞中,使干酪乳杆菌基因组中的LC2W-1628基因被红色荧光蛋白基因替换,从而使干酪乳杆菌LC2W能表达出红色荧光蛋白。得到红色荧光标记的干酪乳杆菌LC2W突变株后,测定了其荧光强度-OD600标准曲线,发现RFP在干酪乳杆菌LC2W中能稳定表达。     

Leptin gene-targeted editing in ob/ob mouse adipose tissue based on the CRISPR/Cas9 system

Gene therapy has become the most effective treatment for monogenic diseases. Congenital LEPTIN deficiency is a rare autosomal recessive monogenic obesity syndrome caused by mutations in the Leptin gene. Ob/ob mouse is a monogenic obesity model, which carries a homozygous point mutation of C to T in Exon 2 of the Leptin gene. Here, we attempted to edit the mutated Leptin gene in ob/ob mice preadipocytes and inguinal adipose tissues using CRISPR/Cas9 to correct the C to T mutation and restore the production of LEPTIN protein by adipocytes. The edited preadipocytes exhibit a correction of 5.5% of Leptin alleles and produce normal LEPTIN protein when differentiated into mature adipocytes. The ob/ob mice display correction of 1.67% of Leptin alleles, which is sufficient to restore the production and physiological functions of LEPTIN protein, such as suppressing appetite and alleviating insulin resistance. Our study suggests CRISPR/Cas9-mediated in situ genome editing as a feasible therapeutic strategy for human monogenic diseases, and paves the way for further research on efficient delivery system in potential future clinical application.     

Development of a CRISPR/Cas9 system in Entamoeba histolytica: proof of concept

The protozoan parasite Entamoeba histolytica is an important human pathogen and a leading parasitic cause of death on a global scale. The lack of molecular tools for genome editing hinders the study of important biological functions of this parasite. Due to its versatility, the CRISPR (clustered regularly interspaced short palindromic repeat)-Cas9 system has been successfully used to induce site-specific genomic alterations, including in protozoan parasites. In this study, we optimised CRISPR-Cas9 for use as a genetic tool in E. histolytica. We chose a single plasmid approach containing both guide RNA (gRNA) and Cas9 nuclease expression cassettes. The amebic U6 promoter was used to drive the expression of the gRNA and its expression was confirmed by Northern blot analysis. Stable transfectant cell lines were obtained using a destabilising domain of dihydrofolate reductase fused to myc-tagged Cas9 (ddCas9). With this system, we were able to induce ddCas9 expression 16 h following treatment with the small molecule ligand trimethoprim (TMP). Stable cell lines expressing ddCas9 and Luc-gRNA or non-specific (NS)-gRNA were transiently transfected with a plasmid containing a mutated luciferase gene (pDeadLuc) targeted by Luc-gRNA and another plasmid with a truncated luciferase gene (pDonorLuc) to restore luciferase expression and consequent activity. We observed that luminescence signal increased for the cell line expressing Luc-gRNA, suggesting that homologous recombination was facilitated by Cas9 activity. This evidence is supported by the presence of chimeric DNA detected by PCR and confirmed by sequencing of the resulting repaired DNA obtained by homologous recombination. We believe this represents the first report of a CRISPR/Cas9 system use in Entamoeba and provides evidence that this genome editing approach can be useful for genetic studies in this early branching eukaryote.     

A CRISPR/Cas9-mediated gene knockout system in Aspergillus luchuensis mut. kawachii

ABSTRACT

We developed an approach to genome editing of the white koji fungus, Aspergillus luchuensis mut. kawachii using clustered regularly interspaced short palindromic repeats (CRISPR)/Cas9 system. Co-transformation of AMA1-based Cas9 and gRNA expression plasmids achieved efficient gene knockout in A. kawachii. The plasmids were easily lost when selective pressure was removed, allowing for successive rounds of genome editing.     

CRISPR/Cas9介导靶向敲除拟南芥BRI1突变体的鉴定

以拟南芥(Arabidopsis thaliana)油菜素内酯受体BRI1为目的基因,利用CRISPR/Cas9基因编辑技术定向编辑拟南芥BRI1,以期获得更多BRI1的突变体,为后续BRI1功能的进一步深入研究奠定基础。通过筛选转基因植株,对编辑后的BRI1进行测序分析,结果显示该突变体中BRI1基因序列由于新碱基的插入导致提前终止。同BRI1强突变体bri1-710一样,相比于野生型对照均对BL处理不敏感,但相比于bri1-710,该突变体植株较大,暗示BRI1 N端可能在BR信号途径中有重要作用。因此该研究可为后续进一步研究拟南芥及其他同源物种的BRI1功能提供可靠的参考依据。     

利用CRISPR/Cas9敲除人源细胞系中LMNA基因的研究

LMNA基因编码A型和C型核纤层蛋白,参与细胞核核膜的组织,影响基因组稳定性并对细胞分化产生影响。人类肿瘤中LMNA表达异常普遍存在,其突变造成多种核纤层蛋白病,如Emery-Dreifuss肌营养不良症(Emery-Dreifussmusculardystrophy,EDMD)、扩张型心肌病(dilatedcardiomyopathy,DCM)和儿童早老症(Hutchinson-Glifordprogeriasyndrome,HGPS)等。为进一步研究LMNA在细胞内的功能,本研究利用CRISPR/Cas9技术对体外培养的293T与HepG2细胞株的LMNA基因进行编辑,获得两株LMNA基因敲除(LMNA KO)的稳定细胞系。与野生型相比,LMNAKO细胞系增殖能力相对减弱,凋亡增加。同时,细胞形态上也发生显著改变,核膜凹凸不平。本研究首次报道了LMNA KO永生细胞系构建和形态研究结果,为后续LMNA基因功能研究和致病突变体研究奠定基础。     

构建基于CRISPR/Cas9技术敲除ALOX5的质粒

旨在利用CRISPR/Cas9技术构建敲除花生四烯5-脂氧合酶基因(Arachidonate 5-lipoxygenase gene,ALOX5)的重组质粒。设计合成3对靶向敲除ALOX5第六外显子的sgRNA,将其分别插入到CRISPR/Cas9质粒骨架pX458载体中,转化感受态大肠杆菌DH5α后挑取克隆,通过测序评估重组质粒是否构建成功。将构建好的重组质粒转染293T细胞,在荧光显微镜下观察转染效果,挑取转染成功的细胞,用试剂盒提取转染细胞基因组DNA,PCR扩增含敲除位点的DNA片段,用测序技术获得核苷酸序列,用DNAStar软件分析转染细胞中ALOX5基因敲除情况。测序结果表明2对双链sgRNA寡核苷酸已插入质粒,且序列正确,靶向ALOX5基因的重组质粒pX458-sgRNAs-ALOX5构建成功。其在293T细胞中的转染效率约为50%,用一代测序法未检测到sgRNAs的切割效果。初步表明利用CRISPR/Cas9技术成功构建靶向ALOX5基因的重组质粒pX458-sgRNAs-ALOX5。     

CRISPR/Cas9介导的二穗短柄草bdfls2敲除突变体的获得

FLS2是一类在植物中保守存在的可识别细菌鞭毛蛋白并激活位于植物先天免疫反应第一层面的重要的植物模式识别受体(pattern recognition receptors,PRRs).为了进一步研究草坪草植物的先天免疫,本研究以冷季型草坪草模式植物二穗短柄草(Brachypodium distachyon)为材料,利用C...