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https://www.readbyqxmd.com/read/28916764/rapid-and-reversible-epigenome-editing-by-endogenous-chromatin-regulators
#1
Simon M G Braun, Jacob G Kirkland, Emma J Chory, Dylan Husmann, Joseph P Calarco, Gerald R Crabtree
Understanding the causal link between epigenetic marks and gene regulation remains a central question in chromatin biology. To edit the epigenome we developed the FIRE-Cas9 system for rapid and reversible recruitment of endogenous chromatin regulators to specific genomic loci. We enhanced the dCas9-MS2 anchor for genome targeting with Fkbp/Frb dimerizing fusion proteins to allow chemical-induced proximity of a desired chromatin regulator. We find that mSWI/SNF (BAF) complex recruitment is sufficient to oppose Polycomb within minutes, leading to activation of bivalent gene transcription in mouse embryonic stem cells...
September 15, 2017: Nature Communications
https://www.readbyqxmd.com/read/28903044/engineering-synthetic-signaling-pathways-with-programmable-dcas9-based-chimeric-receptors
#2
Toni A Baeumler, Ahmed Ashour Ahmed, Tudor A Fulga
Synthetic receptors provide a powerful experimental tool for generation of designer cells capable of monitoring the environment, sensing specific input signals, and executing diverse custom response programs. To advance the promise of cellular engineering, we have developed a class of chimeric receptors that integrate a highly programmable and portable nuclease-deficient CRISPR/Cas9 (dCas9) signal transduction module. We demonstrate that the core dCas9 synthetic receptor (dCas9-synR) architecture can be readily adapted to various classes of native ectodomain scaffolds, linking their natural inputs with orthogonal output functions...
September 12, 2017: Cell Reports
https://www.readbyqxmd.com/read/28879853/dcas9-a-versatile-tool-for-epigenome-editing
#3
Daan J W Brocken, Mariliis Tark-Dame, Remus T Dame
The epigenome is a heritable layer of information not encoded in the DNA sequence of the genome, but in chemical modifications of DNA or histones. These chemical modifications, together with transcription factors, operate as spatiotemporal regulators of genome activity. Dissecting epigenome function requires controlled site-specific alteration of epigenetic information. Such control can be obtained using designed DNA-binding platforms associated with effector domains to function as targeted transcription factors or epigenetic modifiers...
September 7, 2017: Current Issues in Molecular Biology
https://www.readbyqxmd.com/read/28874528/ein2-mediates-direct-regulation-of-histone-acetylation-in-the-ethylene-response
#4
Fan Zhang, Likai Wang, Bin Qi, Bo Zhao, Eun Esther Ko, Nathaniel D Riggan, Kevin Chin, Hong Qiao
Ethylene gas is essential for developmental processes and stress responses in plants. Although the membrane-bound protein EIN2 is critical for ethylene signaling, the mechanism by which the ethylene signal is transduced remains largely unknown. Here we show the levels of H3K14Ac and H3K23Ac are correlated with the levels of EIN2 protein and demonstrate EIN2 C terminus (EIN2-C) is sufficient to rescue the levels of H3K14/23Ac of ein2-5 at the target loci, using CRISPR/dCas9-EIN2-C. Chromatin immunoprecipitation followed by deep sequencing (ChIP-seq) and ChIP-reChIP-seq analyses revealed that EIN2-C associates with histone partially through an interaction with EIN2 nuclear-associated protein1 (ENAP1), which preferentially binds to the genome regions that are associated with actively expressed genes both with and without ethylene treatments...
September 5, 2017: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/28841410/in-situ-capture-of-chromatin-interactions-by-biotinylated-dcas9
#5
Xin Liu, Yuannyu Zhang, Yong Chen, Mushan Li, Feng Zhou, Kailong Li, Hui Cao, Min Ni, Yuxuan Liu, Zhimin Gu, Kathryn E Dickerson, Shiqi Xie, Gary C Hon, Zhenyu Xuan, Michael Q Zhang, Zhen Shao, Jian Xu
Cis-regulatory elements (CREs) are commonly recognized by correlative chromatin features, yet the molecular composition of the vast majority of CREs in chromatin remains unknown. Here, we describe a CRISPR affinity purification in situ of regulatory elements (CAPTURE) approach to unbiasedly identify locus-specific chromatin-regulating protein complexes and long-range DNA interactions. Using an in vivo biotinylated nuclease-deficient Cas9 protein and sequence-specific guide RNAs, we show high-resolution and selective isolation of chromatin interactions at a single-copy genomic locus...
August 24, 2017: Cell
https://www.readbyqxmd.com/read/28832943/crispri-repression-of-nonhomologous-end-joining-for-enhanced-genome-engineering-via-homologous-recombination-in-yarrowia-lipolytica
#6
Cory Schwartz, Keith Frogue, Adithya Ramesh, Joshua Misa, Ian Wheeldon
In many organisms of biotechnological importance precise genome editing is limited by inherently low homologous recombination (HR) efficiencies. A number of strategies exist to increase the effectiveness of this native DNA repair pathway; however, most strategies rely on permanently disabling competing repair pathways, thus reducing an organism's capacity to repair naturally occurring double strand breaks. Here, we describe a CRISPR interference (CRISPRi) system for gene repression in the oleochemical-producing yeast Yarrowia lipolytica...
August 19, 2017: Biotechnology and Bioengineering
https://www.readbyqxmd.com/read/28814758/targeted-insertion-of-an-anti-cd2-monoclonal-antibody-transgene-into-the-ggta1-locus-in-pigs-using-foki-dcas9
#7
Mark B Nottle, Evelyn J Salvaris, Nella Fisicaro, Stephen McIlfatrick, Ivan Vassiliev, Wayne J Hawthorne, Philip J O'Connell, Jamie L Brady, Andrew M Lew, Peter J Cowan
Xenotransplantation from pigs has been advocated as a solution to the perennial shortage of donated human organs and tissues. CRISPR/Cas9 has facilitated the silencing of genes in donor pigs that contribute to xenograft rejection. However, the generation of modified pigs using second-generation nucleases with much lower off-target mutation rates than Cas9, such as FokI-dCas9, has not been reported. Furthermore, there have been no reports on the use of CRISPR to knock protective transgenes into detrimental porcine genes...
August 16, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28813663/a-crispr-activation-screen-identifies-a-pan-avian-influenza-virus-inhibitory-host-factor
#8
Brook E Heaton, Edward M Kennedy, Rebekah E Dumm, Alfred T Harding, Matthew T Sacco, David Sachs, Nicholas S Heaton
Influenza A virus (IAV) is a pathogen that poses significant risks to human health. It is therefore critical to develop strategies to prevent influenza disease. Many loss-of-function screens have been performed to identify the host proteins required for viral infection. However, there has been no systematic screen to identify the host factors that, when overexpressed, are sufficient to prevent infection. In this study, we used CRISPR/dCas9 activation technology to perform a genome-wide overexpression screen to identify IAV restriction factors...
August 15, 2017: Cell Reports
https://www.readbyqxmd.com/read/28808002/optimized-strategy-for-in-vivo-cas9-activation-in-drosophila
#9
Ben Ewen-Campen, Donghui Yang-Zhou, Vitória R Fernandes, Delfina P González, Lu-Ping Liu, Rong Tao, Xingjie Ren, Jin Sun, Yanhui Hu, Jonathan Zirin, Stephanie E Mohr, Jian-Quan Ni, Norbert Perrimon
While several large-scale resources are available for in vivo loss-of-function studies in Drosophila, an analogous resource for overexpressing genes from their endogenous loci does not exist. We describe a strategy for generating such a resource using Cas9 transcriptional activators (CRISPRa). First, we compare a panel of CRISPRa approaches and demonstrate that, for in vivo studies, dCas9-VPR is the most optimal activator. Next, we demonstrate that this approach is scalable and has a high success rate, as >75% of the lines tested activate their target gene...
August 14, 2017: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/28798030/ethanol-exposure-regulates-gabra1-expression-via-histone-deacetylation-at-the-promoter-in-cultured-cortical-neurons
#10
John Peyton Bohnsack, Vraj K Patel, A Leslie Morrow
GABAA-Rs mediate the majority of inhibitory neurotransmission in the adult brain. α1-containing GABAA-Rs are the most prominent subtype in the adult brain, and are important in both homeostatic function and several disease pathologies including alcohol dependence, epilepsy, and stress. Ethanol exposure causes a decrease of α1 transcription and peptide expression both in vivo and in vitro, but the mechanism that controls the transcriptional regulation is unknown. Since ethanol is known to activate epigenetic regulation of gene expression, we tested the hypothesis that ethanol regulates α1 expression through histone modifications in cerebral cortical cultured neurons...
August 10, 2017: Journal of Pharmacology and Experimental Therapeutics
https://www.readbyqxmd.com/read/28757163/evaluating-synthetic-activation-and-repression-of-neuropsychiatric-related-genes-in-hipsc-derived-npcs-neurons-and-astrocytes
#11
Seok-Man Ho, Brigham J Hartley, Erin Flaherty, Prashanth Rajarajan, Rawan Abdelaal, Ifeanyi Obiorah, Natalie Barretto, Hamza Muhammad, Hemali P Phatnani, Schahram Akbarian, Kristen J Brennand
Modulation of transcription, either synthetic activation or repression, via dCas9-fusion proteins is a relatively new methodology with the potential to facilitate high-throughput up- or downregulation studies of gene function. Genetic studies of neurodevelopmental disorders have identified a growing list of risk variants, including both common single-nucleotide variants and rare copy-number variations, many of which are associated with genes having limited functional annotations. By applying a CRISPR-mediated gene-activation/repression platform to populations of human-induced pluripotent stem cell-derived neural progenitor cells, neurons, and astrocytes, we demonstrate that it is possible to manipulate endogenous expression levels of candidate neuropsychiatric risk genes across these three cell types...
August 8, 2017: Stem Cell Reports
https://www.readbyqxmd.com/read/28751638/targeted-dna-methylation-in-human-cells-using-engineered-dcas9-methyltransferases
#12
Tina Xiong, Glenna E Meister, Rachael E Workman, Nathaniel C Kato, Michael J Spellberg, Fulya Turker, Winston Timp, Marc Ostermeier, Carl D Novina
Mammalian genomes exhibit complex patterns of gene expression regulated, in part, by DNA methylation. The advent of engineered DNA methyltransferases (MTases) to target DNA methylation to specific sites in the genome will accelerate many areas of biological research. However, targeted MTases require clear design rules to direct site-specific DNA methylation and minimize the unintended effects of off-target DNA methylation. Here we report a targeted MTase composed of an artificially split CpG MTase (sMTase) with one fragment fused to a catalytically-inactive Cas9 (dCas9) that directs the functional assembly of sMTase fragments at the targeted CpG site...
July 27, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28743878/an-all-in-one-unisam-vector-system-for-efficient-gene-activation
#13
Antonella Fidanza, Martha Lopez-Yrigoyen, Nicola Romanò, Rhiannon Jones, A Helen Taylor, Lesley M Forrester
We have generated a drug-free, all-in-one dCAS9-SAM vector that can activate endogenous gene expression with the potential to modify cell fate. We demonstrate that this strategy can be used in a number of cell lines and avoids exceptionally high levels of gene expression that are observed in standard transgenic approaches. Compared to the multi-plasmid system, this all-in-one vector activates gene expression to a comparable level but the reduced overall DNA content results in significantly higher viability of transfected cells...
July 25, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28730450/crispr-cas-rna-scaffolds-for-transcriptional-programming-in-yeast
#14
Jesse G Zalatan
CRISPR scaffold RNAs (scRNAs) provide a modular system for locus-specific transcriptional programming. scRNAs are generated by extending CRISPR guide RNA sequences with domains that recruit RNA-binding proteins, thus physically linking DNA binding and protein recruitment activities. A single scRNA molecule encodes information about the target locus and instructions about what regulatory function to execute at that locus. Sets of scRNA constructs can be used to generate synthetic multigene transcriptional programs in which some genes are activated and others are repressed...
2017: Methods in Molecular Biology
https://www.readbyqxmd.com/read/28712493/crispr-cas9-enabled-multiplex-genome-editing-and-its-application
#15
Bastian Minkenberg, Matthew Wheatley, Yinong Yang
The CRISPR/Cas9 system is a prevalent and versatile genome-editing tool of choice for basic and applied biological research. An exchange of a 20-bp spacer sequence in the gRNA can easily reprogram Cas9 to target a different DNA site. By expressing or providing multiple gRNAs, the system also enables multiplex genome editing at high efficiencies. Current approaches for providing multiple gRNAs in vivo include the use of multigene cassettes to express several gRNAs, Csy4-based excision, arrays of crRNAs, ribozyme-flanked gRNAs, tRNA-dependent cleavage of gRNAs, and direct introduction of Cas9 proteins preloaded with different gRNAs...
2017: Progress in Molecular Biology and Translational Science
https://www.readbyqxmd.com/read/28703221/manipulation-of-nuclear-architecture-through-crispr-mediated-chromosomal-looping
#16
Stefanie L Morgan, Natasha C Mariano, Abel Bermudez, Nicole L Arruda, Fangting Wu, Yunhai Luo, Gautam Shankar, Lin Jia, Huiling Chen, Ji-Fan Hu, Andrew R Hoffman, Chiao-Chain Huang, Sharon J Pitteri, Kevin C Wang
Chromatin looping is key to gene regulation, yet no broadly applicable methods to selectively modify chromatin loops have been described. We have engineered a method for chromatin loop reorganization using CRISPR-dCas9 (CLOuD9) to selectively and reversibly establish chromatin loops. We demonstrate the power of this technology to selectively modulate gene expression at targeted loci.
July 13, 2017: Nature Communications
https://www.readbyqxmd.com/read/28700213/enabling-graded-and-large-scale-multiplex-of-desired-genes-using-a-dual-mode-dcas9-activator-in-saccharomyces-cerevisiae
#17
Matthew Deaner, Julio Mejia, Hal S Alper
Standard approaches for dCas9-based modification of gene expression are limited in the ability to multiplex targets, establish streamlined cassettes, and utilize commonly studied Pol II promoters. In this work, we repurpose the dCas9-VPR activator to act as a dual-mode activator/repressor that can be programmed solely on the basis of target position at gene loci. Furthermore, we implement this approach using a streamlined Pol II-ribozyme system that allows expression of many sgRNAs from a single transcript...
July 27, 2017: ACS Synthetic Biology
https://www.readbyqxmd.com/read/28695892/targeted-dna-methylation-in-vivo-using-an-engineered-dcas9-mq1-fusion-protein
#18
Yong Lei, Xiaotian Zhang, Jianzhong Su, Mira Jeong, Michael C Gundry, Yung-Hsin Huang, Yubin Zhou, Wei Li, Margaret A Goodell
Comprehensive studies have shown that DNA methylation plays vital roles in both loss of pluripotency and governance of the transcriptome during embryogenesis and subsequent developmental processes. Aberrant DNA methylation patterns have been widely observed in tumorigenesis, ageing and neurodegenerative diseases, highlighting the importance of a systematic understanding of DNA methylation and the dynamic changes of methylomes during disease onset and progression. Here we describe a facile and convenient approach for efficient targeted DNA methylation by fusing inactive Cas9 (dCas9) with an engineered prokaryotic DNA methyltransferase MQ1...
July 11, 2017: Nature Communications
https://www.readbyqxmd.com/read/28683826/identification-and-characterization-of-a-foxa2-regulated-transcriptional-enhancer-at-a-type-2-diabetes-intronic-locus-that-controls-gckr-expression-in-liver-cells
#19
Maykel López Rodríguez, Dorota Kaminska, Kati Lappalainen, Jussi Pihlajamäki, Minna U Kaikkonen, Markku Laakso
BACKGROUND: Genome-wide association studies (GWAS) have identified more than 100 genetic loci associated with type 2 diabetes (T2D). However, the underlying biological mechanisms for many of these associations remain unknown. GWAS signals close to the glucokinase regulatory protein gene (GCKR) have been reported for lipid and glucose metabolism traits and the risk of T2D. We investigated the regulatory function of an intronic locus at GCKR represented by the lead single nucleotide polymorphism (SNP) rs780094...
July 6, 2017: Genome Medicine
https://www.readbyqxmd.com/read/28666380/comparative-analysis-of-chimeric-zfp-tale-and-cas9-piggybac-transposases-for-integration-into-a-single-locus-in-human-cells
#20
Wentian Luo, Daniel L Galvan, Lauren E Woodard, Dan Dorset, Shawn Levy, Matthew H Wilson
Integrating DNA delivery systems hold promise for many applications including treatment of diseases; however, targeted integration is needed for improved safety. The piggyBac (PB) transposon system is a highly active non-viral gene delivery system capable of integrating defined DNA segments into host chromosomes without requiring homologous recombination. We systematically compared four different engineered zinc finger proteins (ZFP), four transcription activator-like effector proteins (TALE), CRISPR associated protein 9 (SpCas9) and the catalytically inactive dSpCas9 protein fused to the amino-terminus of the transposase enzyme designed to target the hypoxanthine phosphoribosyltransferase (HPRT) gene located on human chromosome X...
August 21, 2017: Nucleic Acids Research
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