A screen for cis-regulatory elements for murine miR-142 using an sgRNA library prepared by Molecular Chipper technology
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ABSTRACT: CRISPR-based loss-of-function screens have been proven powerful to identify genetic regulators in mammalian cells, but current approaches for single guide RNA (sgRNA) library construction are expensive and difficult to be adapted in most laboratories. Here, we present a Molecular Chipper technology for inexpensive and easily customizable sgRNA library generation, and a proof-of-principle screen that identifies novel cis-regulatory regions for miR-142 biogenesis. This method will be useful for functional interrogation of non-coding elements in mammalian genomes
Project description:CRISPR interference (CRISPRi) genetic screens use programmable repression of gene expression to systematically explore questions in cell biology and genetics. However, wider adoption of CRISPRi screening has been constrained by the large size of single guide RNA (sgRNA) libraries and lack of consensus on the choice of CRISPRi effector proteins. Here, we address these challenges to present next-generation CRISPRi sgRNA libraries and effectors. First, we combine empiric sgRNA selection with a dual sgRNA library design to generate an ultra-compact, highly active CRISPRi sgRNA library. Next, we rigorously compare CRISPRi effectors to show that the recently published Zim3-dCas9 provides an optimal balance between strong on-target knockdown and minimal nonspecific effects on cell growth or the transcriptome. Finally, we engineer a suite of cell lines which stably express Zim3-dCas9 and demonstrate robust on-target knockdown across these cell lines. Our results and publicly available reagents establish best practices for CRISPRi genetic screening.
Project description:Detecting and mitigating off-target activity is critical to the practical application of CRISPR-mediated genome and epigenome editing. While numerous methods have been developed to map genome-wide sgRNA specificity genome-wide, they are generally time-consuming and/or expensive, and not applicable to catalytically dead CRISPR enzymes. We have developed a rapid, inexpensive, and facile assay for identifying off-target CRISPR binding and cleavage by chemically mapping the unwound single-stranded DNA structures formed upon CRISPR binding (``CasKAS''). We demonstrate this method in both in vitro and in vivo contexts.
Project description:tRNase ZL-utilizing efficacious gene silencing (TRUE gene silencing) is an RNA-mediated gene expression control technology that has therapeutic potential. This technology is based on the properties of tRNase ZL that it can cleave any target RNA at any desired site under the direction of an appropriate artificial small guide RNA (sgRNA) and that cytosolic tRNase ZL can modulate gene expression by cleaving mRNA under the direction of cellular 5M-bM-^@M-2-half-tRNA or microRNA as sgRNA. In order to estimate a number of potential therapeutic heptamer-type sgRNAs for hematological malignancies, we constructed an sgRNA library composed of 156 heptamer-type sgRNAs, and examined how the sgRNAs affect viability of leukemia and myeloma cells. And we found that 20 of the 156 sgRNAs can efficiently induce apoptosis in at least one of the cancer cell lines. Furthermore, we demonstrated that 4 of the 20 effective sgRNAs can reduce growth rates of HL60 cells in mouse xenograft models. DNA microarray analysis for changes in an mRNA profile by these four heptamer-type sgRNAs suggested at least one candidate target mRNA that contains a potential tRNase ZL target site for each sgRNA. Changes in gene expression in HL60 cells were measured after 18-hour incubation in the absence or presence of one of five different heptamer-type sgRNAs. *Heptamer sequences requested but not provided by submitter
Project description:To minimize the human genome-wide CRISPR/Cas9 library size, we established H-mLib which recruited a novel sgRNA design method and applied with dual plasmid based strategy. The performance of the H-mLib was benchmarked to other CRISPR libraries in a proliferation screening conducted in K562 cells. We also identified human core essential genes and cell-type specific essentials genes in K562 and Jurkat cells.
Project description:Analysis of Cas9/sgRNA mutagenic activity at a variety of loci in zebrafish. Each loci has a control, where no Cas9/sgRNA were injected. This is amplicon sequencing with Illumina, after PCR amplification. Data was processed with ampliCan R package version 1.1.1.
Project description:tRNase ZL-utilizing efficacious gene silencing (TRUE gene silencing) is an RNA-mediated gene expression control technology that has therapeutic potential. This technology is based on the properties of tRNase ZL that it can cleave any target RNA at any desired site under the direction of an appropriate artificial small guide RNA (sgRNA) and that cytosolic tRNase ZL can modulate gene expression by cleaving mRNA under the direction of cellular 5′-half-tRNA or microRNA as sgRNA. In order to estimate a number of potential therapeutic heptamer-type sgRNAs for hematological malignancies, we constructed an sgRNA library composed of 156 heptamer-type sgRNAs, and examined how the sgRNAs affect viability of leukemia and myeloma cells. And we found that 20 of the 156 sgRNAs can efficiently induce apoptosis in at least one of the cancer cell lines. Furthermore, we demonstrated that 4 of the 20 effective sgRNAs can reduce growth rates of HL60 cells in mouse xenograft models. DNA microarray analysis for changes in an mRNA profile by these four heptamer-type sgRNAs suggested at least one candidate target mRNA that contains a potential tRNase ZL target site for each sgRNA.
Project description:Analysis of Cas9/sgRNA mutagenic activity at a variety of loci in zebrafish. Each loci has a control, where no Cas9/sgRNA were injected. This is amplicon sequencing with Illumina, after PCR amplification. Data was processed with ampliCan R package version 1.1.1.