CRISPR gene editing

CRISPR gene editing  (technology,  genetic engineering,  Biological weapon/Research,  research)
Start	2012
Interest of	• Jennifer Doudna • Walter Isaacson • Feng Zhang
Breakthrough technology making gene editing easy and fast.

CRISPR gene editing (pronounced "crisper") is a genetic engineering technique in molecular biology by which the genomes of living organisms may be modified. It is based on a simplified version of the bacterial CRISPR-Cas9 antiviral defense system. By delivering the Cas9 nuclease complexed with a synthetic guide RNA (gRNA) into a cell, the cell's genome can be cut at a desired location, allowing existing genes to be removed and/or new ones added in vivo (in living organisms).

The technique is considered highly significant in biotechnology and medicine as it allows for the genomes to be edited in vivo with extremely high precision, cheaply and with ease. It can be used in the creation of new medicines, agricultural products, and genetically modified organisms, or as a means of controlling pathogens and pests. It also has possibilities in the treatment of inherited genetic diseases as well as diseases arising from somatic mutations such as cancer. However, its use in human germline genetic modification is highly controversial.

The development of the technique earned Jennifer Doudna and Emmanuelle Charpentier the Nobel Prize in Chemistry in 2020. Charpentier attended the 2016 Bilderberg conference.

Summary

Working like genetic scissors, the Cas9 nuclease opens both strands of the targeted sequence of DNA to introduce the modification by one of two methods. Knock-in mutations, facilitated via homology directed repair (HDR), is the traditional pathway of targeted genomic editing approaches. This allows for the introduction of targeted DNA damage and repair. HDR employs the use of similar DNA sequences to drive the repair of the break via the incorporation of exogenous DNA to function as the repair template. This method relies on the periodic and isolated occurrence of DNA damage at the target site in order for the repair to commence. Knock-out mutations caused by CRISPR-Cas9 result in the repair of the double-stranded break by means of non-homologous end joining (NHEJ). NHEJ can often result in random deletions or insertions at the repair site, which may disrupt or alter gene functionality. Therefore, genomic engineering by CRISPR-Cas9 gives researchers the ability to generate targeted random gene disruption. Because of this, the precision of genome editing is a great concern. Genomic editing leads to irreversible changes to the genome.

Applications

CRISPR-Cas9 genome editing techniques have many potential applications, including in medicine and agriculture. The use of the CRISPR-Cas9-gRNA complex for genome editing was the AAAS's choice for Breakthrough of the Year in 2015. Many bioethical concerns have been raised about the prospect of using CRISPR for germline editing, especially in human embryos.

Biomedicine

CRISPR-Cas technology has been proposed as a treatment for multiple human diseases, especially those with a genetic cause. Its ability to modify specific DNA sequences makes it a tool with potential to fix disease-causing mutations. Early research in animal models suggest that therapies based on CRISPR technology have potential to treat a wide range of diseases, including cancer, progeria, beta-thalassemia, sickle cell disease,hemophilia, cystic fibrosis,Duchenne's muscular dystrophy, Huntington's disease, and heart disease. CRISPR has also been used to cure malaria in mosquitos, which could eliminate the vector and the disease in humans. CRISPR may also have applications in tissue engineering and regenerative medicine, such as by creating human blood vessels that lack expression of MHC class II proteins, which often cause transplant rejection.

RNA editing

In 2016, researchers demonstrated that CRISPR from an ordinary mouth bacterium could be used to edit RNA. The researchers searched databases containing hundreds of millions of genetic sequences for those that resembled CRISPR genes. They considered the fusobacteria Leptotrichia shahii. It had a group of genes that resembled CRISPR genes, but with important differences. When the researchers equipped other bacteria with these genes, which they called C2c2, they found that the organisms gained a novel defense.

Many viruses encode their genetic information in RNA rather than DNA that they repurpose to make new viruses. HIV and poliovirus are such viruses. Bacteria with Cas13 make molecules that can dismember RNA, destroying the virus. Tailoring these genes opened any RNA molecule to editing.

CRISPR-Cas systems can also be employed for editing of micro-RNA and long-noncoding RNA genes in plants.

Gene Drive Extinction

Main article: Genetic Extinction Technology

A gene drive is an existing technology of genetic engineering that is able to propagate a particular suite of genes throughout a population by altering the probability that a specific allele will be transmitted to offspring (instead of the Mendelian 50% probability). It application is particularly suited for creating an irreversible species extinction.

Prime editing

Prime editing (or base editing) is a CRISPR refinement to accurately insert or delete sections of DNA. The CRISPR edits are not always perfect and the cuts can end up in the wrong place. Both issues are a problem for using the technology in medicine. Prime editing does not cut the double-stranded DNA but instead uses the CRISPR targeting apparatus to shuttle an additional enzyme to a desired sequence, where it converts a single nucleotide into another. The new guide, called a pegRNA, contains an RNA template for a new DNA sequence to be added to the genome at the target location. That requires a second protein, attached to Cas9: a reverse transcriptase enzyme, which can make a new DNA strand from the RNA template and insert it at the nicked site. Those three independent pairing events each provide an opportunity to prevent off-target sequences, which significantly increases targeting flexibility and editing precision. Prime editing was developed by researchers at the Broad Institute of MIT and Harvard in Massachusetts. More work is needed to optimize the methods.

 

Related Quotations

Page	Quote	Author	Date
Biological weapon	“Fabricating scary narratives about superbugs is much easier than delivering on promises of making those bugs in labs. This is also a very productive avenue as people are woefully gullible and thus can be controlled by narratives just as effectively as by an actual scary-scary bioengineered virus. Biodefense is a huge grift on both sides. 'Their' side appropriates money and power, and new billion dollar agencies for 'Pandemic Preparedness'. 'Our' side gets millions of followers talking about them evil guys, or spinning stories about biolabs in Wuhan, Ukraine and lately California. They leak' from labs almost every week, and using CRISPER gene drive narrative logic, all mice in the world should look like Ralph Baric by now.”	Sasha Latypova	November 2023
Walter Isaacson	“For the first time in the evolution of life on this planet, a species has developed the capacity to edit its own genetic makeup. That offers the potential of wondrous benefits, including the elimination of many deadly diseases and debilitating abnormalities.”	Walter Isaacson	2020

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References

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