CRISPR-based epigenome editing screens identify transcriptional and epigenetic regulators of human CD8 T cell function [Sorting-based CRISPR screens]
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ABSTRACT: All bulk CRISPR based screens CD2 and B2M CRISPRi tiling screens (primary human CD8 T cells), IL2RA CRISPRa tiling screens (Jurkats), CRISPRi/a TF screens (primary human CD8 T cells), and CRISPR TFome KO (primary human T cells)
Project description:CRISPR/Cas9-based functional genomics have transformed our ability to elucidate mammalian cell biology. Most previous CRISPR-based screens were implemented in cancer cell lines, rather than healthy, differentiated cells. Here, we describe a CRISPR interference (CRISPRi)-based platform for genetic screens in human neurons derived from induced pluripotent stem cells (iPSCs). We demonstrate robust and durable knockdown of endogenous genes in such neurons, and present results from three complementary genetic screens. A survival-based screen revealed neuron-specific essential genes and a small number of genes that improved neuronal survival upon knockdown. A screen with a single-cell transcriptomic readout uncovered several examples for genes knockdown of which had dramatically different cell-type specific consequences. A longitudinal imaging screen detected distinct consequences of gene knockdown on neuronal morphology. Our results highlight the potential of interrogating cell biology in iPSC-derived differentiated cell types and provide a platform for the systematic dissection of normal and disease states of neurons.
Project description:Pooled CRISPR-Cas9 screens have recently emerged as a powerful method for functionally characterizing regulatory elements in the non-coding genome, but off-target effects in these experiments have not been systematically evaluated. Here, we conducted multiple genome-scale CRISPR screens for essential CTCF loop anchors in the human K562 erythroid cell line. Surprisingly, the primary drivers of apparent ``hits'' in this screen were single guide RNAs (sgRNAs) with low sequence specificity. After removing these confounders, we found that no CTCF loop anchors among the ones we screened are essential for cell growth in culture. We also observed analogous effects in independent non-coding screens densely tiling regulatory elements and genomic neighborhoods near previously known essential genes. Strikingly, we found that low-specificity guides also result in strong confounding growth effects in screens employing epigenetic perturbations that do not cause DNA damage, such as CRISPRi and CRISPRa. Remarkably, the set of confounded guides is distinct for each perturbation mode. Promisingly, strict filtering of CRISPRi libraries using GuideScan-aggregate specificity scores removed these confounded sgRNAs and allowed for the identification of essential enhancers, which we validated extensively. Our stduy presents the first genome-scale functional characterization of CTCF binding sites in the human genome, while also identifying the limitations on and outlining the future prospects for the detailed functional dissection of regulatory elements in the genome using Cas9.
Project description:CRISPR-based epigenome editing screens identify transcriptional and epigenetic regulators of human CD8 T cell function [Sorting-based CRISPR screens]
Project description:This is data for the evaluation of a new way of counting sgRNAs in CRISPR screens using padlock probes and UMIs. It is compared to the typical PCR-based approach. In particular, a dropout screen was performed in MiaPaCa-2 cells using the Human Kinome CRISPR pooled library (Addgene #75314)
Project description:Regulation of cytokine production in stimulated T cells can be disrupted in autoimmunity, immunodeficiencies, and cancer. Systematic discovery of stimulation-dependent cytokine regulators requires both loss-of-function and gain-of-function studies, which have been challenging in primary human cells. We now report genome-wide CRISPR activation (CRISPRa) and interference (CRISPRi) screens in primary human T cells to identify gene networks controlling interleukin 2 and interferon gamma production. Arrayed CRISPRa confirmed key hits and enabled multiplexed secretome characterization, revealing reshaped cytokine responses. Coupling CRISPRa screening with single-cell RNA-seq enabled deep molecular characterization of screen hits, revealing how perturbations tuned T cell activation and promoted cell states characterized by distinct cytokine expression profiles. Together, these screens reveal genes that reprogram critical immune cell functions, which could inform the design of immunotherapies.
Project description:Hundreds of thousands of candidate cis-regulatory elements (cCREs) have been identified across a myriad of cell types, but relatively few have been empirically characterized. Here, we present a scalable, phenotype-driven CRISPR screening method to test thousands of regulatory elements in parallel, by perturbing thousands of DNase hypersensitive sites (DHS) around hundreds of essential genes in K562. Integrating data from Cas9 exon-targeting with our CRISPRi screens, we nominate and validate promoters that regulate other nearby genes. Using higher-resolution CRISPR systems (dCas9 alone or Cas9) to tile across several essential enhancers, we resolve distinct peaks of activity and dissect core transcription factor binding sites (TFBSs) within enhancers, highlighting the advantages of complementary CRISPR systems to investigate CREs. Lastly, we use our tiling results to interrogate how TFBSs interact to drive enhancer function at the CBFA2T3 locus. This study demonstrates a scalable CRISPR screening framework for identifying and dissecting CREs that regulate cellular phenotypes.
Project description:Regulation of cytokine production in stimulated T cells can be disrupted in autoimmunity, immunodeficiencies, and cancer. Systematic discovery of stimulation-dependent cytokine regulators requires both loss-of-function and gain-of-function studies, which have been challenging in primary human cells. We now report genome-wide CRISPR activation (CRISPRa) and interference (CRISPRi) screens in primary human T cells to identify gene networks controlling interleukin 2 and interferon gamma production. Arrayed CRISPRa confirmed key hits and enabled multiplexed secretome characterization, revealing reshaped cytokine responses. Coupling CRISPRa screening with single-cell RNA-seq enabled deep molecular characterization of screen hits, revealing how perturbations tuned T cell activation and promoted cell states characterized by distinct cytokine expression profiles. Together, these screens reveal genes that reprogram critical immune cell functions, which could inform the design of immunotherapies.
Project description:The development of CRISPR genetic screening tools has improved functional genomics, as these tools enable precise genomic editing, provide broad access to genomic regions beyond protein-coding genes, and have fewer off-target effects than other functional genomics modalities, allowing for novel applications with smaller library sizes compared to prior technologies. Pooled functional genomics screens require high cellular coverage per perturbation to accurately quantify phenotypes and average out phenotype-independent variability across the population. While more compact libraries have decreased the number of cells needed for a given screen, the cell coverage required for large-scale CRISPR screens still poses technical hurdles to screen in more challenging systems, such as iPSC-derived and primary cells. A major factor that influences cell coverage is screening library uniformity, as larger variation in individual guide RNA abundance requires higher cell coverage to reliably measure low-abundance guides. In this work, we have systematically optimized guide RNA cloning procedures to decrease bias. We implement these protocols to demonstrate that CRISPRi screens using 10-fold fewer cells than the current standard provides equivalent statistically significant hit-calling results to screens run at higher coverage, opening the possibility of conducting genome-wide and other large-scale CRISPR screens in technically challenging models.
Project description:Acute myeloid leukaemia (AML) continues to have a very high mortality and its treatment hasnot changed for more than 20 years.Here, we propose to apply genomic-wide screens to directly identify therapeutic vulnerabilitiesof AML using AML cells lines with pre-defined somatic mutations. Our studies will be basedon genome-wide CRISPR/CAs9 gRNA screens and will be used to identify drivers of drugresistance to standard chemotherapies.This data is part of a pre-publication release. For information on the proper use of pre-publication data shared by the Wellcome Trust Sanger Institute (including details of any publication moratoria), please see http://www.sanger.ac.uk/datasharing/