Project description:CRISPR-Cas13 systems have been adapted as versatile toolkits for RNA-related applications. Here we systematically evaluate the performance of several prominent Cas13 family effectors (Cas13a, Cas13b and Cas13d) under lentiviral vectors and reveal surprisingly differential defects and characteristics of these systems. Using RNA immunoprecipitation sequencing, transcriptome profiling, biochemistry analysis and high-throughput CRISPR-Cas13 screening approaches, we determine that each Cas13 system has its intrinsic RNA targets in mammalian cells. Viral process-related host genes can be targeted by Cas13 and affect the production of fertile lentiviral particles, thereby restricting the utility of lentiviral Cas13 systems. Multiple RNase activities of Cas13 are involved in endogenous RNA targeting. Unlike target-induced collateral effect, intrinsic RNA targeting can be specific, target-independent and dynamically tuned by varied states of Cas13 nucleases. Our work not only provides guidance to appropriately utilize lentiviral Cas13 systems, but also raises cautions about intrinsic RNA targeting during Cas13-based basic and therapeutic applications.
Project description:CRISPR-Cas13 systems have been adapted as versatile toolkits for RNA-related applications. Here we systematically evaluate the performance of several prominent Cas13 family effectors (Cas13a, Cas13b and Cas13d) under lentiviral vectors and reveal surprisingly differential defects and characteristics of these systems. Using RNA immunoprecipitation sequencing, transcriptome profiling, biochemistry analysis and high-throughput CRISPR-Cas13 screening approaches, we determine that each Cas13 system has its intrinsic RNA targets in mammalian cells. Viral process-related host genes can be targeted by Cas13 and affect the production of fertile lentiviral particles, thereby restricting the utility of lentiviral Cas13 systems. Multiple RNase activities of Cas13 are involved in endogenous RNA targeting. Unlike target-induced collateral effect, intrinsic RNA targeting can be specific, target-independent and dynamically tuned by varied states of Cas13 nucleases. Our work not only provides guidance to appropriately utilize lentiviral Cas13 systems, but also raises cautions about intrinsic RNA targeting during Cas13-based basic and therapeutic applications.
Project description:CRISPR-Cas13 systems have been adapted as versatile toolkits for RNA-related applications. Here we systematically evaluate the performance of several prominent Cas13 family effectors (Cas13a, Cas13b and Cas13d) under lentiviral vectors and reveal surprisingly differential defects and characteristics of these systems. Using RNA immunoprecipitation sequencing, transcriptome profiling, biochemistry analysis and high-throughput CRISPR-Cas13 screening approaches, we determine that each Cas13 system has its intrinsic RNA targets in mammalian cells. Viral process-related host genes can be targeted by Cas13 and affect the production of fertile lentiviral particles, thereby restricting the utility of lentiviral Cas13 systems. Multiple RNase activities of Cas13 are involved in endogenous RNA targeting. Unlike target-induced collateral effect, intrinsic RNA targeting can be specific, target-independent and dynamically tuned by varied states of Cas13 nucleases. Our work not only provides guidance to appropriately utilize lentiviral Cas13 systems, but also raises cautions about intrinsic RNA targeting during Cas13-based basic and therapeutic applications.
Project description:In this study we analyzed the effects of an altered Cas13a expression in vivo, in presence or absence of ectopically expressed protospacer RNA (plasmid pCV2_SB6), by RNA-sequencing. The genomic modification of the cas13a controlling promoter enables altered expression of cas13a by adding either subinhibitory crystal violet (CV) concentrations (for transcriptional repression of cas13a), or additionally IPTG (for transcriptional induction of cas13a), to the mutant cultures. Transcriptome profiles were compared to corresponding wild type controls.
Project description:The study investigates how varying target expression levels influences self-targeting and defense using Cas13a. We see how immunity is activated only over a target transcription threshold, which is variable between targets. A gRNA library targeting transcripts from the whole coding genome of E. coli MG1655 confirms the importance of the transcription threshold in determining immunity and shows that most of the cellular transcripts do not induce cytotoxicity.
Project description:The study investigates how varying target expression levels influences self-targeting and defense using Cas13a. We see how immunity is activated only over a target transcription threshold, which is variable between targets. A gRNA library targeting transcripts from the whole coding genome of E. coli MG1655 confirms the importance of the transcription threshold in determining immunity and shows that most of the cellular transcripts do not induce cytotoxicity.