We describe a rapid and highly efficient method to generate point mutations in Caenorhabditis elegans using direct injection of CRISPR-Cas9 ribonucleoproteins. This versatile method does not require sensitized genetic backgrounds or co-CRISPR selection-based methods, and represents a single strategy that can be used for creating genomic point mutations, regardless of location. As proof of principle, we show that knock-in mutants more faithfully report variant-associated phenotypes as compared to transgenic overexpression. Data for nine knock-in mutants across five genes are presented that demonstrate high editing efficiencies (60%), a reduced screening workload (24 F1 progeny), and a rapid timescale (4-5 d). This optimized method simplifies genome engineering and is readily adaptable to other model systems. KEYWORDS CRISPR Cas9 ribonucleoprotein Caenorhabditis elegans disease variantsNext-generation DNA sequencing technologies have enabled the rapid identification of clinical sequence variants, yet a significant gap still exists in characterizing their functional and pathological significance (Boyd et al. 2014). Moreover, allele frequency is often used as a surrogate to infer disease relevance without functional validation in animal models (Minikel and MacArthur 2016). Introducing site-specific variants in a rapid and facile manner in model organisms would greatly aid in unmasking the pathogenic potential of newly identified sequence variants of unknown significance. Recent technological advances such as the CRISPR-Cas9 genome editing system have revolutionized the ability to precisely engineer the genomes of the most prevalent model organisms used in biomedical research (Frokjaer-Jensen 2013;Doudna and Charpentier 2014;Sander and Joung 2014;Ma and Liu 2015;Dickinson and Goldstein 2016;Sugi 2016). Here, we have developed a simplified CRISPR-Cas9 genome editing method for generating point mutations in the model organism Caenorhabditis elegans. This simplified, optimized, and highly-efficient method obviates the need for sensitized genetic backgrounds, selection-based or co-CRISPR methods, and permits the generation of specific knock-in alleles into any strain background within 4-5 d.Several methods currently exist for engineering the C. elegans genome using CRISPR-Cas9, but the majority of these methods rely on specific genetic backgrounds or co-CRISPR strategies in which screening for the successful edit of one marker gene enriches for the genome edit of interest (Dickinson and Goldstein 2016). Although powerful, these methods do have limitations. For example, the dpy-10 co-CRISPR strategy introduces a point mutation that produces an easily observed dominant roller phenotype (Arribere et al. 2014). Although convenient, introducing selectable phenotype-bearing mutations is undesirable if the strain to edit or the desired point mutation of interest itself exhibits a similar phenotype or a phenotype that might be exacerbated or suppressed by the dpy-10 roller phenotype. Moreover, co-CRISPR strategies rely ...
While the static structure of the nuclear pore complex (NPC) continues to be refined with cryo-EM and x-ray crystallography, in vivo conformational changes of the NPC remain under-explored. We developed sensors that report on the orientation of NPC components by rigidly conjugating mEGFP to different NPC proteins. Our studies show conformational changes to select domains of nucleoporins (Nups) within the inner ring (Nup54, Nup58, Nup62) when transport through the NPC is perturbed and no conformational changes to Nups elsewhere in the NPC. Our results suggest that select components of the NPC are flexible and undergo conformational changes upon engaging with cargo.
The clustered regularly interspersed palindromic repeats (CRISPR)-CRISPR-associated protein 9 (Cas9) prokaryotic adaptive immune defense system has been co-opted as a powerful tool for precise eukaryotic genome engineering. Here, we present a rapid and simple method using chimeric single guide RNAs (sgRNA) and CRISPR-Cas9 Ribonucleoproteins (RNPs) for the efficient and precise generation of genomic point mutations in C. elegans. We describe a pipeline for sgRNA target selection, homology-directed repair (HDR) template design, CRISPR-Cas9-RNP complexing and delivery, and a genotyping strategy that enables the robust and rapid identification of correctly edited animals. Our approach not only permits the facile generation and identification of desired genomic point mutant animals, but also facilitates the detection of other complex indel alleles in approximately 4 - 5 days with high efficiency and a reduced screening workload.
While the static structure of the nuclear pore complex (NPC) continues to be refined with cryo-EM and x-ray crystallography, the in vivo conformational dynamics of the NPC remain under-explored. We developed sensors that report on the orientation of NPC components by rigidly conjugating mEGFP to different NPC proteins. Our studies show conformational changes to select domains of Nups within the inner ring (Nup54, Nup58, Nup62) when transport through the NPC is perturbed and no conformational changes to Nups elsewhere in the NPC. Our results suggest that select components of the NPC are flexible and undergo conformational changes upon engaging with cargo.
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