Project description:Recent cancer genome sequencing studies have identified numerous novel candidate driver genes. In vivo functional investigation of oncogenes using somatic gene transfer has been successfully exploited as a versatile means to validate their pathogenic relevance. In contrast, such functional analyses have been hampered for candidate tumor suppressor genes, e.g. by insufficient knockdown using RNAi-mediated approaches. In order to provide a flexible method for investigating loss-of-function mutations and their potential role in tumorigenesis, we have established CRISPR/Cas9-mediated somatic gene disruption, allowing for in vivo deletion of candidate tumor suppressor genes. We demonstrate the utility of this approach by somatic disruption of the Ptch1 gene in the mouse cerebellum, leading to the formation of medulloblastoma faithfully resembling the SHH-driven subgroup of the disease. This in vivo method for validation of candidate tumor suppressor genes provides a fast and convenient system for the generation of faithful animal models of human cancer.
Project description:CRISPR-Cas systems have revolutionized gene regulation technologies in various organisms, including zebrafish. However, most zebrafish studies rely on transient injections of CRISPR components, with limited use of transgenic models, primarily for Cas9-mediated knockouts. This is largely due to challenges in achieving sustained and effective expression of Cas effectors. To address these challenges, we introduce the CRISPR-Q system, which integrates the QFvpr/QUAS binary expression system with CRISPR-Cas effectors. This approach overcomes limitations associated with transient mRNA or protein delivery and circumvents the toxicity and silencing issues typical of other binary systems, such as Gal4/UAS. The CRISPR-Q system enables robust expression of CasRx or dCas9vpr, facilitating efficient transcript knockdown (CRISPR-QKD) and gene activation (CRISPR-Qa). Using this system, we successfully achieved significant knockdown of smn1 and the simultaneous knockdown of the paralogs tardbp and tardbpl, modeling phenotypes of spinal muscular atrophy (SMA) and amyotrophic lateral sclerosis (ALS), respectively. Furthermore, CRISPR-Qa effectively activated the endogenous genes lin28a and sox9b, demonstrating the system's broad applicability. The CRISPR-Q system represents a significant advancement in zebrafish genetic manipulation, providing a robust and versatile platform for studying gene function and modeling human diseases, with potential extensions to other model organisms
Project description:Mutations in genes encoding epigenetic regulators are among the most frequent somatic events in human cancers. For example, missense and truncating mutations in the MLL3 (KTM2C) histone H3K4-methyltransferase gene can be found in several tumor types. MLL3 is a member of the mixed lineage leukemia gene family and component of the mammalian COMPASS/like complex that promotes gene expression by establishing chromatin modifications favoring gene activation. While Mll3 loss of function promotes tumorigenesis in mice, the molecular targets and biological processes underlying its anti-neoplastic effects remain unknown. Here we combine powerful genetic, genomic, and animal modeling approaches to demonstrate that Mll3 suppresses hepatocellular carcinoma (HCC) by promoting activation of the Cdkn2a (Ink4a/Arf) locus. Hence, disruption of Mll3 using CRISPR/Cas9-mediated genome editing or by RNA interference using short hairpin RNAs cooperates with the Myc oncogene to drive tumorigenesis, producing tumors with reduced H3K4 methylation at multiple gene regulatory elements and low levels of p16Ink4a and p19Arf expression. These results place MLL3 in an established tumor suppressor network and reveal how disruption of a conserved mechanism of epigenetic regulation can alter CDKN2A action and cancer development.
Project description:Mutations in genes encoding epigenetic regulators are among the most frequent somatic events in human cancers. For example, missense and truncating mutations in the MLL3 (KTM2C) histone H3K4-methyltransferase gene can be found in several tumor types. MLL3 is a member of the mixed lineage leukemia gene family and component of the mammalian COMPASS/like complex that promotes gene expression by establishing chromatin modifications favoring gene activation. While Mll3 loss of function promotes tumorigenesis in mice, the molecular targets and biological processes underlying its anti-neoplastic effects remain unknown. Here we combine powerful genetic, genomic, and animal modeling approaches to demonstrate that Mll3 suppresses hepatocellular carcinoma (HCC) by promoting activation of the Cdkn2a (Ink4a/Arf) locus. Hence, disruption of Mll3 using CRISPR/Cas9-mediated genome editing or by RNA interference using short hairpin RNAs cooperates with the Myc oncogene to drive tumorigenesis, producing tumors with reduced H3K4 methylation at multiple gene regulatory elements and low levels of p16Ink4a and p19Arf expression. These results place MLL3 in an established tumor suppressor network and reveal how disruption of a conserved mechanism of epigenetic regulation can alter CDKN2A action and cancer development.
2017-08-01 | GSE85049 | GEO
Project description:Recyclable CRISPR/Cas9 mediated gene disruption and deletions in Histoplasma
Project description:CRISPR technologies have begun to revolutionize T cell therapies; however, conventional CRISPR/Cas9 genome-editing tools are limited in their safety, efficacy, and scope. To address these challenges, we developed MEGA (Multiplexed Effector Guide Arrays), a platform for programmable and scalable regulation of the T cell transcriptome using the RNA-guided, RNA-targeting activity of CRISPR/Cas13d. MEGA enables quantitative, reversible, and massively-multiplexed gene knockdown in primary human T cells without targeting or cutting genomic DNA. Applying MEGA to a model of CAR T cell exhaustion, we robustly suppressed inhibitory receptor upregulation and uncovered paired regulators of T cell function through combinatorial CRISPR screening. We additionally implemented druggable regulation of MEGA to control CAR activation in a receptor-independent manner. Lastly, MEGA enabled multiplexed disruption of immunoregulatory metabolic pathways to enhance CAR T cell fitness and anti-tumor activity in vitro and in vivo. MEGA offers a versatile synthetic toolkit for applications in cancer immunotherapy and beyond.
Project description:Precise targeting of large transgenes to T cells using homology-directed repair has been transformative for adoptive cell therapies and T cell biology. Non-toxic delivery of DNA templates via adeno-associated virus (AAV) has greatly improved knock-in efficiencies, but the tropism of current AAV serotypes restricts their use to human T cells employed in immunodeficient mouse models. To enable targeted knock-ins in murine T cells, we evolved Ark313, a synthetic AAV that exhibits high transduction efficiency in murine T cells. We performed a genome-wide knockout screen and identified QA2 as an essential factor for Ark313 infection. We demonstrate that Ark313 can be used for nucleofection-free DNA delivery, CRISPR/Cas9-mediated knockouts, and targeted integration of large transgenes. Ark313 enables pre-clinical modeling of Trac-targeted CAR-T and transgenic TCR-T cells in immunocompetent models. Efficient gene targeting in murine T cells holds great potential for improved cell therapies and opens new avenues in experimental T cell immunology.
Project description:The CRISPR-Cas9 system enables efficient sequence-specific mutagenesis for creating germline mutants of model organisms. Key constraints in vivo remain the expression and delivery of active Cas9-guideRNA ribonucleoprotein complexes (RNPs) with minimal toxicity, variable mutagenesis efficiencies depending on targeting sequence, and high mutation mosaicism. Here, we established in vitro-assembled, fluorescent Cas9-sgRNA RNPs in stabilizing salt solution to achieve maximal mutagenesis efficiency in zebrafish embryos. Sequence analysis of targeted loci in individual embryos reveals highly efficient bi-allelic mutagenesis that reaches saturation at several tested gene loci. Such virtually complete mutagenesis reveals preliminary loss-of-function phenotypes for candidate genes in somatic mutant embryos for subsequent generation of stable germline mutants. We further show efficient targeting of functional non-coding elements in gene-regulatory regions using saturating mutagenesis towards uncovering functional control elements in transgenic reporters and endogenous genes. Our results suggest that in vitro assembled, fluorescent Cas9-sgRNA RNPs provide a rapid reverse-genetics tool for direct and scalable loss-of-function studies beyond zebrafish applications.