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Dacheng Ma, Shuguang Peng, Weiren Huang, Zhiming Cai, Zhen Xie
Nuclease dead Cas9 (dCas9) has been widely used for modulating gene expression by fusing with different activation or repression domains. However, delivery of the CRISPR/Cas system fused with variant effector domains in a single adeno-associated virus (AAV) remains challenging due to the payload limit. Here, we engineered a set of downsized variants of Cas9 including Staphylococcus aureus Cas9 (SaCas9) that retained DNA binding activity by deleting conserved functional domains. We demonstrated that fusing FokI nuclease domain to the N-terminal of the minimal SaCas9 (mini-SaCas9) or to the middle of the split mini-SaCas9 can trigger efficient DNA cleavage...
March 21, 2018: ACS Synthetic Biology
Xiaoping Su, Kuiqing Cui, Shanshan Du, Hongli Li, Fenghua Lu, Deshun Shi, Qingyou Liu
Myostatin (MSTN), a protein encoded by growth differentiation factor 8 (GDF8), is primarily expressed in skeletal muscle and negatively regulates the development and regeneration of muscle. Accordingly, myostatin-deficient animals exhibit a double-muscling phenotype. The CRISPR/Cas9 system has proven to be an efficient genome-editing tool and has been applied to gene modification in cells from many model organisms such as Drosophila melanogaster, zebrafish, mouse, rat, sheep, and human. Here, we edited the GDF8 gene in fibroblasts and embryos of Debao pig and swamp buffalo using the CRISPR/Cas9 system...
March 19, 2018: In Vitro Cellular & Developmental Biology. Animal
Yufeng Li, Sanyuan Ma, Le Sun, Tong Zhang, Jiasong Chang, Wei Lu, Xiaoxu Chen, Yue Liu, Xiaogang Wang, Run Shi, Ping Zhao, Qingyou Xia
Genome editing using standard tools (ZFN, TALEN, and CRISPR/Cas9) rely on double strand breaks to edit the genome. A series of new CRISPR tools that convert cytidine to thymine (C to T) without the requirement for DNA double-strand breaks was developed recently and quickly applied in a variety of organisms. Here, we demonstrate that CRISPR/Cas9-dependent base editor (BE3) converts C to T with a high frequency in the invertebrate Bombyx mori silkworm. Using BE3 as a knock-out tool, we inactivated exogenous and endogenous genes through base-editing-induced nonsense mutations with an efficiency of up to 66...
March 19, 2018: G3: Genes—Genomes—Genetics
Carin K Ingemarsdotter, Jingwei Zeng, Ziqi Long, Andrew M L Lever, Julia C Kenyon
BACKGROUND: NSC260594, a quinolinium derivative from the NCI diversity set II compound library, was previously identified in a target-based assay as an inhibitor of the interaction between the HIV-1 (ψ) stem-loop 3 (SL3) RNA and Gag. This compound was shown to exhibit potent antiviral activity. Here, the effects of this compound on individual stages of the viral lifecycle were examined by qRT-PCR, ELISA and Western blot, to see if its actions were specific to the viral packaging stage...
March 14, 2018: Retrovirology
Scot P Ouellette
Chlamydia is an obligate intracellular bacterium and, as such, has significantly reduced its genome size and content. Although recent advances have allowed for transformation of C. trachomatis with an exogenous plasmid, genetic manipulation of Chlamydia remains challenging. In particular, the ability to create conditional knockouts has not been developed. This is particularly important given the likelihood that most genes within the small genome of Chlamydia may be essential. Here, I describe the feasibility of using CRISPR interference (CRISPRi) based on the catalytically inactive Cas9 variant (dCas9) of Staphylococcus aureus to inducibly, and reversibly, repress gene expression in C...
2018: Frontiers in Cellular and Infection Microbiology
Audrone Lapinaite, Jennifer A Doudna, Jamie H D Cate
Argonaute proteins (Agos) are present in all domains of life. Although the physiological function of eukaryotic Agos in regulating gene expression is well documented, the biological roles of many of their prokaryotic counterparts remain enigmatic. In some bacteria, Agos are associated with CRISPR (clustered regularly interspaced short palindromic repeats) loci and use noncanonical 5'-hydroxylated guide RNAs (gRNAs) for nucleic acid targeting. Here we show that using 5-bromo-2'-deoxyuridine (BrdU) as the 5' nucleotide of gRNAs stabilizes in vitro reconstituted CRISPR-associated Marinitoga piezophila Argonaute-gRNA complexes (MpAgo RNPs) and significantly improves their specificity and affinity for RNA targets...
March 12, 2018: Proceedings of the National Academy of Sciences of the United States of America
Tyler S Klann, Gregory E Crawford, Timothy E Reddy, Charles A Gersbach
Genomic regulatory elements that control gene expression play an important role in many traits and diseases. Identifying the regulatory elements associated with each gene or phenotype and understanding the function of that element remain a significant challenge. To address this technological need, we developed CRISPR/Cas9-based epigenomic regulatory element screening (CERES) for improved high-throughput screening of regulatory element activity in the native genomic context. This protocol includes detailed instructions for design and cloning of gRNA libraries, construction of endogenous reporter cell lines via CRISPR/Cas9-mediated knock-in of fluorescent proteins, overall screen design, and recovery of the gRNA library for enrichment analysis...
2018: Methods in Molecular Biology
Redmond P Smyth, Maureen R Smith, Anne-Caroline Jousset, Laurence Despons, Géraldine Laumond, Thomas Decoville, Pierre Cattenoz, Christiane Moog, Fabrice Jossinet, Marylène Mougel, Jean-Christophe Paillart, Max von Kleist, Roland Marquet
Non-coding RNA regulatory elements are important for viral replication, making them promising targets for therapeutic intervention. However, regulatory RNA is challenging to detect and characterise using classical structure-function assays. Here, we present in cell Mutational Interference Mapping Experiment (in cell MIME) as a way to define RNA regulatory landscapes at single nucleotide resolution under native conditions. In cell MIME is based on (i) random mutation of an RNA target, (ii) expression of mutated RNA in cells, (iii) physical separation of RNA into functional and non-functional populations, and (iv) high-throughput sequencing to identify mutations affecting function...
March 5, 2018: Nucleic Acids Research
Lien D Bertier, Mily Ron, Heiqiang Huo, Kent J Bradford, Richard W Michelmore
CRISPR/Cas9 is a transformative tool for making targeted genetic alterations. In plants, high mutation efficiencies have been reported in primary transformants. However, many of the mutations analyzed were somatic and therefore not heritable. To provide more insights into the efficiency of creating stable homozygous mutants using CRISPR/Cas9, we targeted LsNCED4 ( 9-cis-epoxycarotenoid dioxygenase4) , a gene conditioning thermoinhibition of seed germination in lettuce. Three constructs, each capable of expressing Cas9 and a single gRNA targeting different sites in LsNCED4 , were stably transformed into lettuce (Lactuca sativa) cvs...
March 6, 2018: G3: Genes—Genomes—Genetics
Mikael Bjursell, Michelle J Porritt, Elke Ericson, Amir Taheri-Ghahfarokhi, Maryam Clausen, Lisa Magnusson, Therese Admyre, Roberto Nitsch, Lorenz Mayr, Leif Aasehaug, Frank Seeliger, Marcello Maresca, Mohammad Bohlooly-Y, John Wiseman
α1-antitrypsin (AAT) is a circulating serine protease inhibitor secreted from the liver and important in preventing proteolytic neutrophil elastase associated tissue damage, primarily in lungs. In humans, AAT is encoded by the SERPINA1 (hSERPINA1) gene in which a point mutation (commonly referred to as PiZ) causes aggregation of the miss-folded protein in hepatocytes resulting in subsequent liver damage. In an attempt to rescue the pathologic liver phenotype of a mouse model of human AAT deficiency (AATD), we used adenovirus to deliver Cas9 and a guide-RNA (gRNA) molecule targeting hSERPINA1...
February 19, 2018: EBioMedicine
Alžběta Dostálková, Filip Kaufman, Ivana Křížová, Anna Kultová, Karolína Strohalmová, Romana Hadravová, Tomáš Ruml, Michaela Rumlová
In addition to specific RNA-binding zinc finger domains, retroviral Gag polyprotein contains clusters of basic amino acid residues thought to support Gag-viral genomic RNA (gRNA) interactions. One of these clusters is the basic K16 NK18 EK20 region, located upstream of the first zinc finger of the Mason-Pfizer monkey virus (M-PMV) nucleocapsid protein (NC). To investigate the role of this basic region in the M-PMV life cycle, we used a combination of in vivo and in vitro methods to study a series of mutants in which the overall charge of this region was more positive (RNRER), more negative (AEAEA), or neutral (AAAAA)...
February 28, 2018: Journal of Virology
Toshitsugu Fujita, Fusako Kitaura, Asami Oji, Naoki Tanigawa, Miyuki Yuno, Masahito Ikawa, Ichiro Taniuchi, Hodaka Fujii
We developed the engineered DNA-binding molecule-mediated chromatin immunoprecipitation (enChIP) technology to isolate specific genomic regions while retaining their molecular interactions. In enChIP, the locus of interest is tagged with an engineered DNA-binding molecule, such as a modified form of the clustered regularly interspaced short palindromic repeats (CRISPR) system containing a guide RNA (gRNA) and a catalytically inactive form of Cas9 (dCas9). The locus is then affinity-purified to enable identification of associated molecules...
February 26, 2018: Genes to Cells: Devoted to Molecular & Cellular Mechanisms
Zheng Hu, Zhaoying Shi, Xiaogang Guo, Baishan Jiang, Guo Wang, Dixian Luo, Yonglong Chen, Yuan-Shan Zhu
Background: Precise genome editing is essential for both basic and translational research. The recently developed CRISPR/Cas9 system can specifically cleave a designated site of target gene to create a DNA double-strand break, which triggers cellular DNA repair mechanism of either inaccurate non-homologous end joining, or site-specific homologous recombination. Unfortunately, homology-directed repair (HDR) is challenging due to its very low efficiency. Herein, we focused on improving the efficiency of HDR using a combination of CRISPR/Cas9, eGFP, DNA ligase IV inhibitor SCR7, and single-stranded oligodeoxynucleotides (ssODN) in human cancer cells...
2018: Cell & Bioscience
Dan Ding, Kaiyuan Chen, Yuedan Chen, Hong Li, Kabin Xie
The Clustered Regularly Interspaced Short Palindromic Repeat (CRISPR) system has emerged as the revolutionary platform for DNA targeting. This system uses a site-specific RNA guide to direct a CRISPR effector (e.g., Cas9 and Cpf1) to a DNA target. Here, we elaborate a general strategy to simultaneously express multiple guide RNAs (gRNA) and CRISPR RNAs (crRNA) from introns of Cas9 and Cpf1. This method utilizes the endogenous tRNA processing system or crRNA processing activity of Cpf1 to cleave the spliced intron which contains tRNA-gRNA polycistron or crRNA-crRNA array...
February 17, 2018: Molecular Plant
Jiazhang Lian, Zehua Bao, Sumeng Hu, Huimin Zhao
The CRISPR/Cas9 system has been widely used for multiplex genome engineering of Saccharomyces cerevisiae. However, its application in manipulating industrial yeast strains is less successful, probably due to the genome complexity and low copy numbers of gRNA expression plasmids. Here we developed an efficient CRISPR/Cas9 system for industrial yeast strain engineering by using our previously engineered plasmids with increased copy numbers. Four genes in both a diploid strain (Ethanol Red, 8 alleles in total) and a triploid strain (ATCC 4124, 12 alleles in total) were knocked out in a single step with 100% efficiency...
February 20, 2018: Biotechnology and Bioengineering
Yu Liu, Miaoxian Zhao, Mingxing Gong, Ying Xu, Cantao Xie, Haohui Deng, Xueying Li, Hongkai Wu, Zhanhui Wang
Chronic hepatitis B virus (HBV) infection is difficult to cure due to the presence of covalently closed circular DNA (cccDNA). Accumulating evidence indicates that the CRISPR/Cas9 system effectively disrupts HBV genome, including cccDNA, in vitro and in vivo. However, efficient delivery of CRISPR/Cas9 system to the liver or hepatocytes using an adeno-associated virus (AAV) vector remains challenging due to the large size of Cas9 from Streptococcus pyogenes (Sp). The recently identified Cas9 protein from Staphylococcus aureus (Sa) is smaller than SpCas9 and thus is able to be packaged into the AAV vector...
February 16, 2018: Antiviral Research
Qian Wang, Li Xiao, Lin Zhou, Wanping Sun, Chungen Xing, Kai Li, Nongyue He
The present study was designed to test a new strategy for comparing the off-target effects of CRISPR/cas9 employing a blue/white colony based assay. Eight types of AmpR plasmids with matched, one base mismatched, two bases mismatched and three bases mismatched targets were constructed. The wild typed alpha peptide of the beta-glactosidase gene and some with mutations, chosen as the targets, were successfully subcloned into the plasmids in an inframe pattern. The relevant gRNA and cas9 were subcloned into the ChloR plasmid...
March 1, 2018: Journal of Nanoscience and Nanotechnology
Janina Gergen, Flora Coulon, Alison Creneguy, Nathan Elain-Duret, Alejandra Gutierrez, Olaf Pinkenburg, Els Verhoeyen, Ignacio Anegon, Tuan Huy Nguyen, Franck Albert Halary, Fabienne Haspot
Anti-HCMV treatments used in immunosuppressed patients reduce viral replication, but resistant viral strains can emerge. Moreover, these drugs do not target latently infected cells. We designed two anti-viral CRISPR/Cas9 strategies to target the UL122/123 gene, a key regulator of lytic replication and reactivation from latency. The singleplex strategy contains one gRNA to target the start codon. The multiplex strategy contains three gRNAs to excise the complete UL122/123 gene. Primary fibroblasts and U-251 MG cells were transduced with lentiviral vectors encoding Cas9 and one or three gRNAs...
2018: PloS One
Brenda R Lemos, Adam C Kaplan, Ji Eun Bae, Alexander E Ferrazzoli, James Kuo, Ranjith P Anand, David P Waterman, James E Haber
Harnessing CRISPR-Cas9 technology provides an unprecedented ability to modify genomic loci via DNA double-strand break (DSB) induction and repair. We analyzed nonhomologous end-joining (NHEJ) repair induced by Cas9 in budding yeast and found that the orientation of binding of Cas9 and its guide RNA (gRNA) profoundly influences the pattern of insertion/deletions (indels) at the site of cleavage. A common indel created by Cas9 is a 1-bp (+1) insertion that appears to result from Cas9 creating a 1-nt 5' overhang that is filled in by a DNA polymerase and ligated...
February 13, 2018: Proceedings of the National Academy of Sciences of the United States of America
Hannes Juergens, Javier A Varela, Arthur R Gorter de Vries, Thomas Perli, Veronica J M Gast, Nikola Y Gyurchev, Arun S Rajkumar, Robert Mans, Jack T Pronk, John P Morrissey, Jean-Marc G Daran
While CRISPR-Cas9-mediated genome editing has transformed yeast research, current plasmids and cassettes for Cas9 and guide-RNA expression are species specific. CRISPR tools that function in multiple yeast species could contribute to the intensifying research on non-conventional yeasts. A plasmid carrying a pangenomic origin of replication and two constitutive expression cassettes, for Cas9 and a ribozyme-flanked gRNAs was constructed. Its functionality was tested by analyzing inactivation of the ADE2 gene in four yeast species...
February 9, 2018: FEMS Yeast Research
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