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https://www.readbyqxmd.com/read/28212815/systematic-testing-of-enzyme-perturbation-sensitivities-via-graded-dcas9-modulation-in-saccharomyces-cerevisiae
#1
Matthew Deaner, Hal S Alper
Dissecting genotype-phenotype relationships in a high-throughput and scalable manner is still an unresolved problem facing metabolic engineers. While the RNA-guided nuclease Cas9 has been repurposed as a programmable transcription regulator, its application has typically been limited to binary on/off regulation and thus misses informative and potentially optimal intermediate levels of gene expression. In this work, we establish a rapid method for fine-tuned, graded expression of pathway enzymes via dCas9 regulation by varying sgRNA target location as the dominant parameter...
February 14, 2017: Metabolic Engineering
https://www.readbyqxmd.com/read/28179021/switch-a-dynamic-crispr-tool-for-genome-engineering-and-metabolic-pathway-control-for-cell-factory-construction-in-saccharomyces-cerevisiae
#2
Katherina García Vanegas, Beata Joanna Lehka, Uffe Hasbro Mortensen
BACKGROUND: The yeast Saccharomyces cerevisiae is increasingly used as a cell factory. However, cell factory construction time is a major obstacle towards using yeast for bio-production. Hence, tools to speed up cell factory construction are desirable. RESULTS: In this study, we have developed a new Cas9/dCas9 based system, SWITCH, which allows Saccharomyces cerevisiae strains to iteratively alternate between a genetic engineering state and a pathway control state...
February 8, 2017: Microbial Cell Factories
https://www.readbyqxmd.com/read/28143571/single-cas9-nickase-induced-generation-of-nramp1-knockin-cattle-with-reduced-off-target-effects
#3
Yuanpeng Gao, Haibo Wu, Yongsheng Wang, Xin Liu, Linlin Chen, Qian Li, Chenchen Cui, Xu Liu, Jingcheng Zhang, Yong Zhang
BACKGROUND: The CRISPR-Cas9 system is a widely utilized platform for transgenic animal production in various species, although its off-target effects should be addressed. Several applications of this tool have been proposed in model animals but remain insufficient for transgenic livestock production. RESULTS: Here, we report the first application of single Cas9 nickase (Cas9n) to induce gene insertion at a selected locus in cattle. We identify the main binding sites of a catalytically inactive Cas9 (dCas9) protein in bovine fetal fibroblast cells (BFFs) with chromatin immunoprecipitation sequencing (ChIP-seq)...
February 1, 2017: Genome Biology
https://www.readbyqxmd.com/read/28136159/crispr-cas-type-ii-based-synthetic-biology-applications-in-eukaryotic-cells
#4
Mario Andrea Marchisio, Zhiwei Huang
The CRISPR-Cas system has rapidly reached a huge popularity as a new, powerful method for precise DNA editing and genome reengineering. In Synthetic Biology, the CRISPR-Cas type II system has inspired the construction of a novel class of RNA-based transcription factors. In their simplest form, they are made of a CRISPR RNA molecule, which targets a promoter sequence, and a deficient Cas9 (i.e. deprived of any nuclease activity) that has been fused to an activation or a repression domain. Up- and down-regulation of single genes in mammalian and yeast cells have been achieved with satisfactory results...
January 31, 2017: RNA Biology
https://www.readbyqxmd.com/read/28116670/an-inducible-crispr-on-system-for-controllable-gene-activation-in-human-pluripotent-stem-cells
#5
Jianying Guo, Dacheng Ma, Rujin Huang, Jia Ming, Min Ye, Kehkooi Kee, Zhen Xie, Jie Na
Human pluripotent stem cells (hPSCs) are an important system to study early human development, model human diseases, and develop cell replacement therapies. However, genetic manipulation of hPSCs is challenging and a method to simultaneously activate multiple genomic sites in a controllable manner is sorely needed. Here, we constructed a CRISPR-ON system to efficiently upregulate endogenous genes in hPSCs. A doxycycline (Dox) inducible dCas9-VP64-p65-Rta (dCas9-VPR) transcription activator and a reverse Tet transactivator (rtTA) expression cassette were knocked into the two alleles of the AAVS1 locus to generate an iVPR hESC line...
January 23, 2017: Protein & Cell
https://www.readbyqxmd.com/read/28095853/crispri-mediated-metabolic-engineering-of-e-coli-for-o-methylated-anthocyanin-production
#6
Brady F Cress, Quentin D Leitz, Daniel C Kim, Teresita D Amore, Jon Y Suzuki, Robert J Linhardt, Mattheos A G Koffas
BACKGROUND: Anthocyanins are a class of brightly colored, glycosylated flavonoid pigments that imbue their flower and fruit host tissues with hues of predominantly red, orange, purple, and blue. Although all anthocyanins exhibit pH-responsive photochemical changes, distinct structural decorations on the core anthocyanin skeleton also cause dramatic color shifts, in addition to improved stabilities and unique pharmacological properties. In this work, we report for the first time the extension of the reconstituted plant anthocyanin pathway from (+)-catechin to O-methylated anthocyanins in a microbial production system, an effort which requires simultaneous co-option of the endogenous metabolites UDP-glucose and S-adenosyl-L-methionine (SAM or AdoMet)...
January 17, 2017: Microbial Cell Factories
https://www.readbyqxmd.com/read/28072927/artificial-induction-of-native-aquaporin-1-expression-in-human-salivary-cells
#7
Z Wang, S Pradhan-Bhatt, M C Farach-Carson, M J Passineau
Gene therapy for dry mouth disorders has transitioned in recent years from theoretical to clinical proof of principle with the publication of a first-in-man phase I/II dose escalation clinical trial in patients with radiation-induced xerostomia. This trial used a prototype adenoviral vector to express aquaporin-1 (AQP1), presumably in the ductal cell layer and/or in surviving acinar cells, to drive transcellular flux of interstitial fluid into the labyrinth of the salivary duct. As the development of this promising gene therapy continues, safety considerations are a high priority, particularly those that remove nonhuman agents (i...
January 1, 2017: Journal of Dental Research
https://www.readbyqxmd.com/read/28069948/genomic-targeting-of-epigenetic-probes-using-a-chemically-tailored-cas9-system
#8
Glen P Liszczak, Zachary Z Brown, Samuel H Kim, Rob C Oslund, Yael David, Tom W Muir
Recent advances in the field of programmable DNA-binding proteins have led to the development of facile methods for genomic localization of genetically encodable entities. Despite the extensive utility of these tools, locus-specific delivery of synthetic molecules remains limited by a lack of adequate technologies. Here we combine the flexibility of chemical synthesis with the specificity of a programmable DNA-binding protein by using protein trans-splicing to ligate synthetic elements to a nuclease-deficient Cas9 (dCas9) in vitro and subsequently deliver the dCas9 cargo to live cells...
January 24, 2017: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/28046023/a-model-to-investigate-single-strand-dna-responses-in-g1-human-cells-via-a-telomere-targeted-nuclease-deficient-crispr-cas9-system
#9
Remco P Crefcoeur, Omar Zgheib, Thanos D Halazonetis
DNA replication stress has the potential to compromise genomic stability and, therefore, cells have developed elaborate mechanisms to detect and resolve problems that may arise during DNA replication. The presence of single-stranded DNA (ssDNA) is often associated with DNA replication stress and serves as a signal for both checkpoint and repair responses. In this study, we exploited a CRISPR-Cas9 system to induce regions of ssDNA in the genome. Specifically, single-guide RNAs bearing sequence complementarity to human telomeric repeats, were used to target nuclease-deficient Cas9 (dCas9) to telomeres...
2017: PloS One
https://www.readbyqxmd.com/read/27983975/current-status-of-potential-applications-of-repurposed-cas9-for-structural-and-functional-genomics-of-plants
#10
Kunal Seth, Harish
Redesigned Cas9 has emerged as a tool with various applications like gene editing, gene regulation, epigenetic modification and chromosomal imaging. Target specific single guide RNA (sgRNA) can be used with Cas9 for precise gene editing with high efficiency than previously known methods. Further, nuclease-deactivated Cas9 (dCas9) can be fused with activator or repressor for activation (CRISPRa) and repression (CRISPRi) of gene expression, respectively. dCas9 fused with epigenetic modifier like methylase or acetylase further expand the scope of this technique...
October 28, 2016: Biochemical and Biophysical Research Communications
https://www.readbyqxmd.com/read/27965712/targeted-inhibition-of-the-mir-199a-214-cluster-by-crispr-interference-augments-the-tumor-tropism-of-human-induced-pluripotent-stem-cell-derived-neural-stem-cells-under-hypoxic-condition
#11
Yumei Luo, Xuehu Xu, Xiuli An, Xiaofang Sun, Shu Wang, Detu Zhu
The human induced pluripotent stem cell (hiPSC) provides a breakthrough approach that helps overcoming ethical and allergenic challenges posed in application of neural stem cells (NSCs) in targeted cancer gene therapy. However, the tumor-tropic capacity of hiPSC-derived NSCs (hiPS-NSCs) still has much room to improve. Here we attempted to promote the tumor tropism of hiPS-NSCs by manipulating the activity of endogenous miR-199a/214 cluster that is involved in regulation of hypoxia-stimulated cell migration...
2016: Stem Cells International
https://www.readbyqxmd.com/read/27960483/single-molecule-localization-and-discrimination-of-dna-protein-complexes-by-controlled-translocation-through-nanocapillaries
#12
Roman D Bulushev, Sanjin Marion, Ekaterina Petrova, Sebastian J Davis, Sebastian J Maerkl, Aleksandra Radenovic
Through the use of optical tweezers we performed controlled translocations of DNA-protein complexes through nanocapillaries. We used RNA polymerase (RNAP) with two binding sites on a 7.2 kbp DNA fragment and a dCas9 protein tailored to have five binding sites on λ-DNA (48.5 kbp). Measured localization of binding sites showed a shift from the expected positions on the DNA that we explained using both analytical fitting and a stochastic model. From the measured force versus stage curves we extracted the nonequilibrium work done during the translocation of a DNA-protein complex and used it to obtain an estimate of the effective charge of the complex...
December 14, 2016: Nano Letters
https://www.readbyqxmd.com/read/27955725/current-status-of-potential-applications-of-repurposed-cas9-for-structural-and-functional-genomics-of-plants
#13
Kunal Seth, Harish
Redesigned Cas9 has emerged as a tool with various applications like gene editing, gene regulation, epigenetic modification and chromosomal imaging. Target specific single guide RNA (sgRNA) can be used with Cas9 for precise gene editing with high efficiency than previously known methods. Further, nuclease-deactivated Cas9 (dCas9) can be fused with activator or repressor for activation (CRISPRa) and repression (CRISPRi) of gene expression, respectively. dCas9 fused with epigenetic modifier like methylase or acetylase further expand the scope of this technique...
November 25, 2016: Biochemical and Biophysical Research Communications
https://www.readbyqxmd.com/read/27934604/generation-of-induced-pluripotent-stem-cells-ipscs-stably-expressing-crispr-based-synergistic-activation-mediator-sam
#14
Kai Xiong, Yan Zhou, Poul Hyttel, Lars Bolund, Kristine Karla Freude, Yonglun Luo
Human fibroblasts were engineered to express the CRISPR-based synergistic activation mediator (SAM) complex: dCas9-VP64 and MS2-P65-HSF1. Two induced pluripotent stem cells (iPSCs) clones expressing SAM were established by transducing these fibroblasts with lentivirus expressing OCT4, SOX2, KLF4 and C-MYC. We have validated that the reprogramming cassette is silenced in the SAM iPSC clones. Expression of pluripotency genes (OCT4, SOX2, LIN28A, NANOG, GDF3, SSEA4, and TRA-1-60), differentiation potential to all three germ layers, and normal karyotypes are validated...
November 17, 2016: Stem Cell Research
https://www.readbyqxmd.com/read/27905063/efficient-gene-targeting-in-mouse-zygotes-mediated-by-crispr-cas9-protein
#15
Chris J Jung, Junli Zhang, Elizabeth Trenchard, Kent C Lloyd, David B West, Barry Rosen, Pieter J de Jong
The CRISPR/Cas9 system has rapidly advanced targeted genome editing technologies. However, its efficiency in targeting with constructs in mouse zygotes via homology directed repair (HDR) remains low. Here, we systematically explored optimal parameters for targeting constructs in mouse zygotes via HDR using mouse embryonic stem cells as a model system. We characterized several parameters, including single guide RNA cleavage activity and the length and symmetry of homology arms in the construct, and we compared the targeting efficiency between Cas9, Cas9nickase, and dCas9-FokI...
November 30, 2016: Transgenic Research
https://www.readbyqxmd.com/read/27903907/chromatin-binding-of-gcn5-in-drosophila-is-largely-mediated-by-cp190
#16
Tamer Ali, Marcus Krüger, Sabin Bhuju, Michael Jarek, Marek Bartkuhn, Rainer Renkawitz
Centrosomal 190 kDa protein (CP190) is a promoter binding factor, mediates long-range interactions in the context of enhancer-promoter contacts and in chromosomal domain formation. All Drosophila insulator proteins bind CP190 suggesting a crucial role in insulator function. CP190 has major effects on chromatin, such as depletion of nucleosomes, high nucleosomal turnover and prevention of heterochromatin expansion. Here, we searched for enzymes, which might be involved in CP190 mediated chromatin changes. Eighty percent of the genomic binding sites of the histone acetyltransferase Gcn5 are colocalizing with CP190 binding...
November 29, 2016: Nucleic Acids Research
https://www.readbyqxmd.com/read/27899645/efficient-targeted-dna-methylation-with-chimeric-dcas9-dnmt3a-dnmt3l-methyltransferase
#17
Peter Stepper, Goran Kungulovski, Renata Z Jurkowska, Tamir Chandra, Felix Krueger, Richard Reinhardt, Wolf Reik, Albert Jeltsch, Tomasz P Jurkowski
DNA methylation plays a critical role in the regulation and maintenance of cell-type specific transcriptional programs. Targeted epigenome editing is an emerging technology to specifically regulate cellular gene expression in order to modulate cell phenotypes or dissect the epigenetic mechanisms involved in their control. In this work, we employed a DNA methyltransferase Dnmt3a-Dnmt3L construct fused to the nuclease-inactivated dCas9 programmable targeting domain to introduce DNA methylation into the human genome specifically at the EpCAM, CXCR4 and TFRC gene promoters...
November 29, 2016: Nucleic Acids Research
https://www.readbyqxmd.com/read/27899566/asymmetric-positioning-of-cas1-2-complex-and-integration-host-factor-induced-dna-bending-guide-the-unidirectional-homing-of-protospacer-in-crispr-cas-type-i-e-system
#18
K N R Yoganand, R Sivathanu, Siddharth Nimkar, B Anand
CRISPR-Cas system epitomizes prokaryote-specific quintessential adaptive defense machinery that limits the genome invasion of mobile genetic elements. It confers adaptive immunity to bacteria by capturing a protospacer fragment from invading foreign DNA, which is later inserted into the leader proximal end of CRIPSR array and serves as immunological memory to recognize recurrent invasions. The universally conserved Cas1 and Cas2 form an integration complex that is known to mediate the protospacer invasion into the CRISPR array...
January 9, 2017: Nucleic Acids Research
https://www.readbyqxmd.com/read/27846887/crispr-interference-crispri-for-gene-regulation-and-succinate-production-in-cyanobacterium-s-elongatus-pcc-7942
#19
Chun-Hung Huang, Claire R Shen, Hung Li, Li-Yu Sung, Meng-Ying Wu, Yu-Chen Hu
BACKGROUND: Cyanobacterium Synechococcus elongatus PCC 7942 holds promise for biochemical conversion, but gene deletion in PCC 7942 is time-consuming and may be lethal to cells. CRISPR interference (CRISPRi) is an emerging technology that exploits the catalytically inactive Cas9 (dCas9) and single guide RNA (sgRNA) to repress sequence-specific genes without the need of gene knockout, and is repurposed to rewire metabolic networks in various procaryotic cells. RESULTS: To employ CRISPRi for the manipulation of gene network in PCC 7942, we integrated the cassettes expressing enhanced yellow fluorescent protein (EYFP), dCas9 and sgRNA targeting different regions on eyfp into the PCC 7942 chromosome...
November 15, 2016: Microbial Cell Factories
https://www.readbyqxmd.com/read/27842593/easy-regulation-of-metabolic-flux-in-escherichia-coli-using-an-endogenous-type-i-e-crispr-cas-system
#20
Yizhao Chang, Tianyuan Su, Qingsheng Qi, Quanfeng Liang
BACKGROUND: Clustered regularly interspaced short palindromic repeats interference (CRISPRi) is a recently developed powerful tool for gene regulation. In Escherichia coli, the type I CRISPR system expressed endogenously shall be easy for internal regulation without causing metabolic burden in compared with the widely used type II system, which expressed dCas9 as an additional plasmid. RESULTS: By knocking out cas3 and activating the expression of CRISPR-associated complex for antiviral defense (Cascade), we constructed a native CRISPRi system in E...
November 15, 2016: Microbial Cell Factories
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