Category: Genome Editing

The Applications of Genome Editing Technology

Genome editing technology enables manipulations at genome level where DNA is replaced, deleted or inserted in a living organism. Classic genome editing approaches depend on homology-directed repair and the totipotency of stem cells to facilitate the modification of the individual gene. The Nobel Prize in Physiology or Medicine 2007 was awarded to the discoveries of principles for introducing specific gene modifications in mice by the use of embryonic stem cells. Because the traditional HDR approach has disadvantages of low efficiency, high technical requirements and high cost, which seriously restricted its applications in large-scale genomic manipulation research. In 2013 the discovery of the type II CRISPR-Cas9 system has promoted the development of precise genetic modifications. This new RNA-mediated DNA editing approach opens up new avenues for the application of genome editing technology in Animal model construction, genetic disease treatment and agricultural breeding.

Genome editing technology——Generation of Animal models

CRISPR-Cas9 system performs precise targeting and editing a specific DNA sequence of interest via a programmable mechanism, and provides a versatile approach to establish transgenic animal models. While mouse models have been widely used, the CRISPR-Cas9 gene-editing approach has been established in many other animal models, including worm, rat, rabbit, pig and monkey. New mouse models can be generated with CRISPR-Cas9 by injecting Cas9 mRNA and guide RNAs (sgRNA) directly into mouse embryos to generate precise genomic edits into specific loci with an efficiency of 100%. CRISPR-Cas9 mediated targeting and editing has facilitated the generation of knockin and knockout mouse models, dramatically decreases the time and resource consumption comparing to traditional methods.

Genome editing technology——Curing genetic diseases

Although CRISPR-Cas9 has already has been widely used as a research tool, a particularly exciting future direction is the development of CRISPR-Cas9 as a therapeutic technology for treating genetic disorders. Researchers at Chinese Academy of Sciences reported successful correction of disease-causing mutations in cataract mouse models via the CRISPR-Cas9 system. Upon injection of CRISPR-Cas9 into zygotes, 1/3 genetic defect in the cataract mouse model could be corrected at the organism level and more importantly the corrected trait was successfully transmitted to the next generation through the germline.

Genome editing technology——Agricultural breeding

The CRISPR-Cas9 technology opens up exciting possibilities for creating crop varieties with desirable traits without introducing foreign DNA. Precision breeding crops with desirable traits, such as disease resistance and drought tolerance not only help reduce pesticide, fertilizer and water usage, but also improve food quality and safety. Researchers at Penn State University created mushrooms with reduced production of a specific enzyme that causes mushrooms to blemishes caused by handling or mechanical harvesting. It becomes the first CRISPR-edited organism to receive a green light from the US government, means that the mushroom can be cultivated and sold without passing through the agency’s regulatory process.

CRISPR-Cas9 is an emerging technology that enables precise genome modification without introducing foreign genes. This transformative tool holds great promises to revolutionize biological research and expand our ability correcting the genetic causes behind many diseases.

Synbio Technologies establish the CRISPR-Cas9 gene/genome editing platform which can offer a one-stop solution for CRISPR-Cas9 projects. We can offer the services including: CRISPR-Cas9 sgRNA design, CRISPR-Cas9 sgRNA library design and genome editing.

Genome Editing Technology vs Transgenic Technology

Genome editing technology

Genome editing technology enables genetic engineering where DNA is replaced, deleted or inserted in the genome of a living organism, and the emergence of CRISPR-Cas9 system has further facilitated the realization of precise genetic modifications. Gene mapping and precise genetic modifications by inducing targeted DNA double-strand breaks opened up new avenues for the application of genome editing technology in drug development, gene therapy, agricultural breeding, environmental protection and endangered animal rescue.

Transgenic technology

Transgenics describes the process of introducing foreign DNA into a host organism’s genome. The foreign DNA, or “transgene,” that is transferred to the recipient can be from other individuals of the same species, from different species or even from artificially synthesized DNA. The foreign DNA was incorporated into the host genome by either homologous recombination or non-homologous recombination, and the following trait selection on a population allows cultivar development within a species to create offspring with desirable traits.

The difference between genome editing technology and transgenic technology

Both Genome editing technology and transgenic techniques can alter the genome of an organism so that the desirable trait can be inherited, but there is a big difference between the two. Genome editing is the manipulation of the genome of the organism itself by knocking out or replacing targeted gene which resulting in individuals with intentionally selected and desired traits, while transgenic technology can only introduce biologically nonexisting foreign genes to the original organisms in order to tailor the species with new traits. Therefore, the use of gene editing technology, can be fast, accurate and without the introduction of exogenous DNA fragments in the case of the organism genome transformation. The US Department of Agriculture (USDA) has shown lenient to genetically modified crops comparing to its controversial transgenic sibling. The decision means that the genetically modified crops can be cultivated and sold without passing through the agency’s regulatory process. The green light from USDA allows the flourish of valuable and disease-resistant crops while bypassing the use of controversial transgenic technologies.

The Comparison Between Three Generation Genome Editing Technologies

Genome editing refers to a type of genetic engineering in which DNA is replaced, deleted or inserted in the genome of a living organism using engineered nucleases. These engineered nucleases enable efficient and precise genetic modifications by inducing targeted DNA double-strand breaks (DSBs) that stimulate the cellular DNA repair mechanisms, There are currently three families of engineered nucleases being used, zinc finger nucleases (ZFNs), transcription activator-like effector-based nucleases (TALEN), and the CRISPR-Cas system.

The mechanism of ZFN and TALEN system

ZFN and TALENs undergo similar molecular mechanisms for executing genome editing. ZFN and TALENs are both engineered nucleases composed of a DNA binding domain that recognize a specific nucleotide triplet based on the residues in their helix and a FokI nuclease motif that have a strong catalytic cleavage capability for specific nucleotides. The FokI domains must dimerize for activity, thus increasing target specificity by ensuring that two proximal DNA-binding events must occur to achieve a double-strand break (DSBs). These chimeric nucleases enable efficient and precise genetic modifications by inducing targeted DNA DSBs that stimulate the cellular DNA repair mechanisms, including error-prone non-homologous end joining (NHEJ) and homology-directed repair (HDR).

The mechanism of CRISPR system

CRISPR is a ubiquitous family of clustered repetitive DNA elements present in 90% of Archaea and 40% of sequenced Bacteria. The CRISPR system was first identified as an adaptive defensive mechanism that confers resistance to foreign genetic elements. Later on, CRISPR-Cas system was engineered into a versatile gene-editing tool enabling manipulation of protospacer adjacent motif (PAM) downstream DNA. CRISPR-Cas9 genome editing system consists of two components: a “guide” RNA (gRNA) and a non-specific CRISPR-associated endonuclease (Cas9). The Cas9 protein is an endonuclease that uses guide RNA molecule (gRNA) to form base pairs with DNA target sequences, enabling Cas9 to introduce a site-specific DSB in the DNA. The CRISPR-Cas9 system offers unprecedented advantages over the ZFN and TALEN strategies. Due to its simplicity and efficiency, CRISPR-Cas9 system has quickly become the go-to genome engineering tool for animal model construction, drug development, gene therapy, agricultural breeding and many other applications.

Based on our knowledge and years of experience in DNA technology, Synbio Technologies has developed CRISPR-Cas9 gene/genome editing platform. We offer a one-stop solution for CRISPR-Cas9 projects to achieve high genome editing efficiency, including CRISPR-Cas9 sgRNA design, CRISPR-Cas9 sgRNA library design and genome editing.