scholarly journals Multiplex enCas12a screens detect functional buffering among paralogs otherwise masked in monogenic Cas9 knockout screens

2020 ◽  
Vol 21 (1) ◽  
Author(s):  
Merve Dede ◽  
Megan McLaughlin ◽  
Eiru Kim ◽  
Traver Hart
Keyword(s):  
Cell Lines ◽  
Protein Complexes ◽  
Gene Knockout ◽  
Essential Genes ◽  
Loss Of Function ◽  
Systematic Analysis ◽  
Synthetic Lethal ◽  
Synthetic Lethal Interactions ◽  
Crispr Screen ◽  
A Cell

Abstract Background Pooled library CRISPR/Cas9 knockout screening across hundreds of cell lines has identified genes whose disruption leads to fitness defects, a critical step in identifying candidate cancer targets. However, the number of essential genes detected from these monogenic knockout screens is low compared to the number of constitutively expressed genes in a cell. Results Through a systematic analysis of screen data in cancer cell lines generated by the Cancer Dependency Map, we observe that half of all constitutively expressed genes are never detected in any CRISPR screen and that these never-essentials are highly enriched for paralogs. We investigated functional buffering among approximately 400 candidate paralog pairs using CRISPR/enCas12a dual-gene knockout screening in three cell lines. We observe 24 synthetic lethal paralog pairs that have escaped detection by monogenic knockout screens at stringent thresholds. Nineteen of 24 (79%) synthetic lethal interactions are present in at least two out of three cell lines and 14 of 24 (58%) are present in all three cell lines tested, including alternate subunits of stable protein complexes as well as functionally redundant enzymes. Conclusions Together, these observations strongly suggest that functionally redundant paralogs represent a targetable set of genetic dependencies that are systematically under-represented among cell-essential genes in monogenic CRISPR-based loss of function screens.

scholarly journals Multiplex enCas12a screens show functional buffering by paralogs is systematically absent from genome-wide CRISPR/Cas9 knockout screens

2020 ◽  
Author(s):  
Merve Dede ◽  
Megan McLaughlin ◽  
Eiru Kim ◽  
Traver Hart
Keyword(s):  
Cell Lines ◽  
Protein Complexes ◽  
Essential Genes ◽  
Systematic Analysis ◽  
Synthetic Lethal ◽  
Genome Wide ◽  
Synthetic Lethal Interactions ◽  
Crispr Screen ◽  
A Cell ◽  
Genetic Buffering

AbstractMajor efforts on pooled library CRISPR knockout screening across hundreds of cell lines have identified genes whose disruption leads to fitness defects, a critical step in identifying candidate cancer targets. However, the number of essential genes detected from these monogenic knockout screens are very low compared to the number of constitutively expressed genes in a cell, raising the question of why there are so few essential genes. Through a systematic analysis of screen data in cancer cell lines generated by the Cancer Dependency Map, we observed that half of all constitutively-expressed genes are never hits in any CRISPR screen, and that these never-essentials are highly enriched for paralogs. We investigated paralog buffering through systematic dual-gene CRISPR knockout screening by testing algorithmically defined ~400 candidate paralog pairs with the enCas12a multiplex knockout system in three cell lines. We observed 24 synthetic lethal paralog pairs which have escaped detection by monogenic knockout screens at stringent thresholds. Nineteen of 24 (79%) synthetic lethal interactions were present in at least two out of three cell lines and 14 of 24 (58%) were present in all three cell lines tested, including alternate subunits of stable protein complexes as well as functionally redundant enzymes. Together these observations strongly suggest that paralogs represent a targetable set of genetic dependencies that are systematically under-represented among cell-essential genes due to genetic buffering in monogenic CRISPR-based mammalian functional genomics approaches.

scholarly journals Combinatorial CRISPR screen identifies fitness effects of gene paralogues

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Nicola A. Thompson ◽  
Marco Ranzani ◽  
Louise van der Weyden ◽  
Vivek Iyer ◽  
Victoria Offord ◽  
...  
Keyword(s):  
Cancer Cells ◽  
Cell Lines ◽  
Unknown Function ◽  
Single Copy ◽  
Genetic Redundancy ◽  
Synthetic Lethal ◽  
Fitness Effects ◽  
Synthetic Lethal Interactions ◽  
Crispr Screen ◽  
Multiple Cell

AbstractGenetic redundancy has evolved as a way for human cells to survive the loss of genes that are single copy and essential in other organisms, but also allows tumours to survive despite having highly rearranged genomes. In this study we CRISPR screen 1191 gene pairs, including paralogues and known and predicted synthetic lethal interactions to identify 105 gene combinations whose co-disruption results in a loss of cellular fitness. 27 pairs influence fitness across multiple cell lines including the paralogues FAM50A/FAM50B, two genes of unknown function. Silencing of FAM50B occurs across a range of tumour types and in this context disruption of FAM50A reduces cellular fitness whilst promoting micronucleus formation and extensive perturbation of transcriptional programmes. Our studies reveal the fitness effects of FAM50A/FAM50B in cancer cells.

scholarly journals Chronos: a cell population dynamics model of CRISPR experiments that improves inference of gene fitness effects

2021 ◽  
Vol 22 (1) ◽  
Author(s):  
Joshua M. Dempster ◽  
Isabella Boyle ◽  
Francisca Vazquez ◽  
David E. Root ◽  
Jesse S. Boehm ◽  
...  
Keyword(s):  
Copy Number ◽  
Gene Knockout ◽  
Loss Of Function ◽  
Explicit Model ◽  
Dynamics Model ◽  
Fitness Effects ◽  
Population Dynamics Model ◽  
Crispr Screen ◽  
A Cell ◽  
Pan Cancer

AbstractCRISPR loss of function screens are powerful tools to interrogate biology but exhibit a number of biases and artifacts that can confound the results. Here, we introduce Chronos, an algorithm for inferring gene knockout fitness effects based on an explicit model of cell proliferation dynamics after CRISPR gene knockout. We test Chronos on two pan-cancer CRISPR datasets and one longitudinal CRISPR screen. Chronos generally outperforms competitors in separation of controls and strength of biomarker associations, particularly when longitudinal data is available. Additionally, Chronos exhibits the lowest copy number and screen quality bias of evaluated methods. Chronos is available at https://github.com/broadinstitute/chronos.

scholarly journals Functional CRISPR Screening Identifies Ptprg As a Driver of Migration and Adhesion in NSD2-E1099K ALL

Blood ◽  
2021 ◽  
Vol 138 (Supplement 1) ◽  
pp. 1149-1149
Author(s):  
Charlotte L Kaestner ◽  
Amin Sobh ◽  
Jianping Li ◽  
Alberto Riva ◽  
Richard Lynn Bennett ◽  
...  
Keyword(s):  
Candidate Genes ◽  
Cell Lines ◽  
Essential Gene ◽  
Gene Knockout ◽  
Lymphoblastic Leukemia ◽  
Tyrosine Phosphatase ◽  
Brain Parenchyma ◽  
High Dose ◽  
Loss Of Function

Abstract Background: Acute Lymphoblastic Leukemia (ALL) is the most common childhood cancer and frequently infiltrates the central nervous system (CNS). CNS-directed therapy is currently limited to intrathecal and systemic high-dose methotrexate, or less commonly craniospinal irradiation, both of which are associated with substantial neurotoxicity. A lack of mechanistic understanding of the mechanisms of CNS infiltration presents an obstacle for the development of more specific and less toxic therapeutic approaches. We previously showed that ALL cells with a specific mutation (E1099K) in the histone methyltransferase NSD2 have aggressive CNS tropism by not only infiltrating the leptomeninges but also the brain parenchyma in murine xenografts models. Analysis of cBioPortal data shows that NSD2-E1099K is associated with a higher rate of testicular involvement in ALL also suggesting more aggressive infiltration behavior of the tumor. Accordingly, using gene editing to revert mutant NSD2 back to wild-type, we also showed that NSD2-E1099K cells have an enhanced ability to migrate and adhere in vitro. RNA-seq data on four NSD2-E1099K cell lines revealed genes that may play a role in ALL brain infiltration. However, it remains unknown which of those upregulated genes could be potential therapeutic targets against CNS leukemia. Aim: This study aims to Identify therapeutically targetable genes that are important for migration of NSD2-E1099K ALL cells Methods: Using a focused CRISPR-gene-knockout library of 5600 sgRNAs directed against 500 genes upregulated in NSD2-E1099K cells, we ascertained the necessity of the selected genes for migration in the RCH-ACV cell line. Candidate genes were evaluated for cellular dependency using a CRISPR-loss of function screen and the cancer dependency map portal. Overexpression of the candidate genes in NSD2-E1099K cell lines was confirmed with qPCR analysis. Candidate genes were validated by individual shRNA knockdown followed by migration and adhesion assays. Results: Our study identified genes whose knockout led to enhancement of migration and others whose knockout resulted in inhibition of migration. Protein Tyrosine Phosphatase Receptor Type G (PTPRG) was one of the top candidate genes whose knockout resulted in inhibition of migration. Dependency map analysis showed that PTPRG is not a commonly essential gene and a CRISPR-based-loss-of function screen performed in parallel to the migration screen confirmed that ALL cell survival is not dependent on PTPRG. We also found that PTPRG is overexpressed in multiple NSD2-E1099K ALL cell lines. Individual Knockdown of PTPRG in NSD2-E1099K ALL cell lines not only inhibited migration, but also led to a loss of adhesion ability to endothelial cells of the Blood Brain Barrier. Conclusions: Our findings implicate PTPRG as an important modulator of migration and adhesion in ALL cells and a potential therapeutic target for preventing ALL brain infiltration, especially in NSD2-E1099K ALL. Disclosures Licht: Epizyme: Research Funding.

scholarly journals Biological network topology features predict gene dependencies in cancer cell lines

2019 ◽  
Author(s):  
Graeme Benstead-Hume ◽  
Sarah K. Wooller ◽  
Samantha Dias ◽  
Lisa Woodbine ◽  
Anthony M. Carr ◽  
...  
Keyword(s):  
Cell Line ◽  
Cell Lines ◽  
Cancer Cell ◽  
Individual Cell ◽  
Cancer Cell Line ◽  
Cancer Cell Lines ◽  
Genetic Alterations ◽  
Essential Genes ◽  
Loss Of Function ◽  
Ppi Network

AbstractIn this paper we explore computational approaches that enable us to identify genes that have become essential in individual cancer cell lines. Using recently published experimental cancer cell line gene essentiality data, human protein-protein interaction (PPI) network data and individual cell-line genomic alteration data we have built a range of machine learning classification models to predict cell line specific acquired essential genes. Genetic alterations found in each individual cell line were modelled by removing protein nodes to reflect loss of function mutations and changing the weights of edges in each PPI to reflect gain of function mutations and gene expression changes.We found that PPI networks can be used to successfully classify human cell line specific acquired essential genes within individual cell lines and between cell lines, even across tissue types with AUC ROC scores of between 0.75 and 0.85. Our novel perturbed PPI network models further improved prediction power compared to the base PPI model and are shown to be more sensitive to genes on which the cell becomes dependent as a result of other changes. These improvements offer opportunities for personalised therapy with each individual’s cancer cell dependencies presenting a potential tailored drug target.The overriding motivation for predicting cancer cell line specific acquired essential genes is to provide a low-cost approach to identifying personalised cancer drug targets without the cost of exhaustive loss of function screening.

scholarly journals Genome-wide synthetic lethal CRISPR screen identifies FIS1 as a genetic interactor of ALS-linked C9ORF72

2019 ◽  
Author(s):  
Noori Chai ◽  
Michael S. Haney ◽  
Julien Couthouis ◽  
David W. Morgens ◽  
Alyssa Benjamin ◽  
...  
Keyword(s):  
Genetic Interaction ◽  
Mitochondrial Fission ◽  
Loss Of Function ◽  
Synthetic Lethal ◽  
Genome Wide ◽  
A Genome ◽  
Crispr Screen ◽  
Insight Into ◽  
Mitochondrial Membrane Protein ◽  
Lateral Sclerosis

AbstractMutations in the C9ORF72 gene are the most common cause of amyotrophic lateral sclerosis (ALS). Both toxic gain of function and loss of function pathogenic mechanisms have been proposed. Accruing evidence from mouse knockout studies point to a role for C9ORF72 as a regulator of immune function. To provide further insight into its cellular function, we performed a genome-wide synthetic lethal CRISPR screen in human myeloid cells lacking C9ORF72. We discovered a strong synthetic lethal genetic interaction between C9ORF72 and FIS1, which encodes a mitochondrial membrane protein involved in mitochondrial fission and mitophagy. Mass spectrometry experiments revealed that in C9ORF72 knockout cells, FIS1 strongly bound to a class of immune regulators that activate the receptor for advanced glycation end (RAGE) products and trigger inflammatory cascades. These findings present a novel genetic interactor for C9ORF72 and suggest a compensatory role for FIS1 in suppressing inflammatory signaling in the absence of C9ORF72.

scholarly journals MYC Oncogene Contributions to Release of Cell Cycle Brakes

Genes ◽  
2019 ◽  
Vol 10 (3) ◽  
pp. 244 ◽  
Author(s):  
Lucía García-Gutiérrez ◽  
María Dolores Delgado ◽  
Javier León
Keyword(s):  
Cell Cycle ◽  
Transcriptional Level ◽  
Synthetic Lethal ◽  
Myc Oncogene ◽  
Synthetic Lethal Interactions ◽  
A Cell ◽  
Functional Inactivation ◽  
P27 Gene ◽  
Cell Cycle Inhibitors

Promotion of the cell cycle is a major oncogenic mechanism of the oncogene c-MYC (MYC). MYC promotes the cell cycle by not only activating or inducing cyclins and CDKs but also through the downregulation or the impairment of the activity of a set of proteins that act as cell-cycle brakes. This review is focused on the role of MYC as a cell-cycle brake releaser i.e., how MYC stimulates the cell cycle mainly through the functional inactivation of cell cycle inhibitors. MYC antagonizes the activities and/or the expression levels of p15, ARF, p21, and p27. The mechanism involved differs for each protein. p15 (encoded by CDKN2B) and p21 (CDKN1A) are repressed by MYC at the transcriptional level. In contrast, MYC activates ARF, which contributes to the apoptosis induced by high MYC levels. At least in some cells types, MYC inhibits the transcription of the p27 gene (CDKN1B) but also enhances p27’s degradation through the upregulation of components of ubiquitin ligases complexes. The effect of MYC on cell-cycle brakes also opens the possibility of antitumoral therapies based on synthetic lethal interactions involving MYC and CDKs, for which a series of inhibitors are being developed and tested in clinical trials

scholarly journals Evaluation and Design of Genome-wide CRISPR/Cas9 Knockout Screens

2017 ◽  
Author(s):  
Traver Hart ◽  
Amy Tong ◽  
Katie Chan ◽  
Jolanda Van Leeuwen ◽  
Ashwin Seetharaman ◽  
...  
Keyword(s):  
Cell Lines ◽  
Human Cell ◽  
Viral Vectors ◽  
Human Cancer ◽  
Gene Knockout ◽  
Essential Genes ◽  
Human Cell Lines ◽  
Protein Coding ◽  
Mammalian Cell Lines ◽  
Genome Scale

AbstractThe adaptation of CRISPR/Cas9 technology to mammalian cell lines is transforming the study of human functional genomics. Pooled libraries of CRISPR guide RNAs (gRNAs), targeting human protein-coding genes and encoded in viral vectors, have been used to systematically create gene knockouts in a variety of human cancer and immortalized cell lines, in an effort to identify whether these knockouts cause cellular fitness defects. Previous work has shown that CRISPR screens are more sensitive and specific than pooled library shRNA screens in similar assays, but currently there exists significant variability across CRISPR library designs and experimental protocols. In this study, we re-analyze 17 genome-scale knockout screens in human cell lines from three research groups using three different genome-scale gRNA libraries, using the Bayesian Analysis of Gene Essentiality (BAGEL) algorithm to identify essential genes, to refine and expand our previously defined set of human core essential genes, from 360 to 684 genes. We use this expanded set of reference Core Essential Genes (CEG2), plus empirical data from six CRISPR knockout screens, to guide the design of a sequence-optimized gRNA library, the Toronto KnockOut version 3.0 (TKOv3) library. We demonstrate the high effectiveness of the library relative to reference sets of essential and nonessential genes as well as other screens using similar approaches. The optimized TKOv3 library, combined with the CEG2 reference set, provide an efficient, highly optimized platform for performing and assessing gene knockout screens in human cell lines.

scholarly journals Variable dose analysis: A novel RNAi-based method for detection of synthetic lethal interactions

2017 ◽  
Author(s):  
Benjamin E. Housden ◽  
Zhongchi Li ◽  
Colleen Kelley ◽  
Yuanli Wang ◽  
Yanhui Hu ◽  
...  
Keyword(s):  
Drug Targets ◽  
Limited Range ◽  
Synthetic Lethal ◽  
Candidate Drug ◽  
Highly Sensitive ◽  
Synthetic Lethal Interactions ◽  
A Cell ◽  
Approved Drugs ◽  
Fda Approved Drugs ◽  
Variable Dose

AbstractSynthetic sick or synthetic lethal (SS/L) screens are a powerful way to identify candidate drug targets to specifically kill tumor cells but such screens generally suffer from low reproducibility. We found that many SS/L interactions involve essential genes and are therefore detectable within a limited range of knockdown efficiency. Such interactions are often missed by overly efficient RNAi reagents. We therefore developed an assay that measures viability over a range of knockdown efficiency within a cell population. This method, called variable dose analysis (VDA), is highly sensitive to viability phenotypes and reproducibly detects SS/L interactions. We applied the VDA method to search for SS/L interactions with TSC1 and TSC2, the two tumor suppressors underlying tuberous sclerosis complex (TSC) and generated a SS/L network for TSC. Using this network, we identified four FDA-approved drugs that selectively affect viability of TSC deficient cells, representing promising candidates for repurposing to treat TSC-related tumors.

scholarly journals Viral protein engagement of GBF1 induces host cell vulnerability through synthetic lethality

2020 ◽  
Author(s):  
Arti T Navare ◽  
Fred D Mast ◽  
Jean Paul Olivier ◽  
Thierry Bertomeu ◽  
Maxwell Neal ◽  
...  
Keyword(s):  
Protein Interactions ◽  
Viral Protein ◽  
Synthetic Lethality ◽  
Host Cells ◽  
Loss Of Function ◽  
Host Proteins ◽  
Synthetic Lethal ◽  
Cancer Driver ◽  
Synthetic Lethal Interactions ◽  
Infected Cells

AbstractViruses co-opt host proteins to carry out their lifecycle. Repurposed host proteins may thus become functionally compromised; a situation analogous to a loss-of-function mutation. We term such host proteins viral-induced hypomorphs. Cells bearing cancer driver loss-of-function mutations have successfully been targeted with drugs perturbing proteins encoded by the synthetic lethal partners of cancer-specific mutations. Synthetic lethal interactions of viral-induced hypomorphs have the potential to be similarly targeted for the development of host-based antiviral therapeutics. Here, we use GBF1, which supports the infection of many RNA viruses, as a proof-of-concept. GBF1 becomes a hypomorph upon interaction with the poliovirus protein 3A. Screening for synthetic lethal partners of GBF1 revealed ARF1 as the top hit, disruption of which, selectively killed cells that synthesize poliovirus 3A. Thus, viral protein interactions can induce hypomorphs that render host cells vulnerable to perturbations that leave uninfected cells intact. Exploiting viral-induced vulnerabilities could lead to broad-spectrum antivirals for many viruses, including SARS-CoV-2.SummaryUsing a viral-induced hypomorph of GBF1, Navare et al., demonstrate that the principle of synthetic lethality is a mechanism to selectively kill virus-infected cells.

Sign in / Sign up

Export Citation Format

Share Document