CRISPR Gene Editing: An Overview


Clustered regularly interspaced short palindromic repeats, or CRISPR, make up a family of DNA sequences that are present in the genomes of prokaryotic organisms, like bacteria and archaea. The sequences are derived from DNA fragments of bacteriophages that have infected the prokaryote. With CRISPR gene editing technologies, scientists can use these bacteriophage fragments to modify the DNA of living organisms like animals and plants.

CRISPR gene editing sees scientists insert or delete DNA to activate or deactivate genes, which, in turn, can cure or prevent otherwise incurable diseases. CRISPR can also make treatments less expensive, delay age-related diseases, and enable those working in agriculture to breed the animals and plants that will benefit the farming industry most. As a result, CRISPR is both key to the future of medical treatments and the future of agriculture, among an array of other sectors. 

In this overview of CRISPR, we’ll cover why this kind of gene editing is important, how CRISPR gene editing works, how CRISPR screening can progress drug discovery, and how CRISPR is likely to affect the future of science and medicine. 

As CRISPR becomes increasingly widely adopted, research professionals from around the world turn to the life sciences journal BioTechniques to learn about CRISPR-related breakthrough methods and techniques. Those looking to learn more about CRISPR will find a wealth of information on the BioTechniques website.

Why CRISPR Gene Editing Is Important

Although CRISPR is relatively new to the genomics space, having only been around for approximately a decade, this kind of gene editing has already enabled big leaps in biomedical research. Before scientists discovered how to edit DNA in living cells in 2012, they used alternative methods to edit animal and plant genomes. However, these methods were time-consuming and costly, and CRISPR gene editing is much easier and more cost-effective to perform.

In 2020, Jennifer Doudna and Emmanuelle Charpentier won the Nobel Prize for their work developing CRISPR. Doudna and Charpentier published a paper entitled “A Programmable Dual-RNA-Guided DNA Endonuclease in Adaptive Bacterial Immunity,” which details how CRISPR can cut specific sites in DNA. Since the publication of this paper, CRISPR has become increasingly standardized in various medical and scientific applications.

More specifically, scientists have adopted CRISPR technologies to direct evolution, produce gene drives and fingerprint cells, and log activity in these cells. They have also used CRISPR to develop smart cells that can track our health from within. In future, it may become possible to log a cell’s biography. 

On top of this, scientists can employ CRISPR to identify what makes cancer cells cancerous, breed muscular police dogs, and grow drought-resistant maize. And, during the Covid-19 pandemic, scientists used CRISPR to produce rapid diagnostic tests. With potential like this, it’s no surprise that CRISPR is transforming medicine on a large scale. 

How CRISPR Gene Editing Works

CRISPR gene editing utilizes Cas proteins, which help the body defend against viruses and are present in bacteria. For example, scientists can program the Cas9 protein to find and bind the protein to a target sequence. Giving the protein a piece of RNA allows the binding process to work. This RNA guides the protein in its search for the desired target sequence.

Adding a CRISPR/Cas9 protein to a cell with a piece of guide RNA allows the protein and guide RNA to combine and travel along the strands of DNA until they locate and bind to a sequence of 20 bases. This sequence matches part of the guide RNA sequence. (The DNA in each of our cells has 6 billion bases, so to say that a sequence of 20 DNA bases is tiny would be an understatement.) 

Next, the Cas9 protein cuts the DNA at its target. When scientists repair the cut, they introduce mutations that usually disable a gene. The results of this process aren’t always as precise as the term suggests, but new CRISPR techniques can make mutations more predictable.

Sometimes, scientists can control, instead of modify, genes to prevent genetic diseases and improve health. As an example, scientists can employ customized Cas proteins to turn genes on or off (CRISPRa and CRISPRi, respectively). They may even change one base of the DNA code to fix unwanted mutations. This approach is an alternative to altering or cutting DNA.

Cas9 proteins may have been integral to the original CRISPR system, but scientists have now conceptualized a variety of other CRISPR systems. For example, other enzymes, like the Cas12a protein, can trigger different outcomes, enabling scientists to develop CRISPR systems for different applications. Therefore, whether scientists use CRISPR to control or alter DNA, this type of gene editing can make it possible to eliminate diseases like AIDS, blood disorders, cystic fibrosis, Huntington’s disease, and muscular dystrophy.

How CRISPR Screening Can Progress Drug Discovery

CRISPR screening allows researchers to test for genes, which is important when it comes to medical research for diseases like cancer. Traditional screening methods can be time-consuming, complex, and offer low-resolution data output. 

However, modern screening methods allow quicker, simpler workflows that enable scientists to understand gene expression and disease pathways, and identify drug targets for diseases. As an example, CRISPR screening has made it possible for scientists to find a new drug target for acute myeloid leukemia, which could lead to the development of a new therapeutic against cancer.

CRISPR screening is becoming a more standardized practice in sectors outside of medical research too. For example, genetic knockout technology could prevent cows from suffering miscarriages in the agriculture industry. With CRISPR screening, scientists may be able to develop healthy embryos for the greatest chance of successful cattle pregnancies.

The Future of CRISPR Gene Editing

As CRISPR-related technologies continue to emerge, the potential for this kind of gene editing continues to grow. In future, CRISPR may make it possible to:

  • Treat and prevent diseases like HIV and heart disease.
  • Develop drugs that tackle obesity.
  • Progress gene therapies for organ transplantation.
  • Access healthier, flavorsome food products.
  • Breed horn-free cattle and a higher proportion of female animals to lessen the slaughter of male animals, who are often killed at birth because they aren’t needed for agricultural or research reasons.
  • Prevent children from inheriting genetic disorders, allowing them to live longer, healthier lives. Many individuals currently consider this kind of genetic engineering premature. However, with development and regulations, preventing genetic disorders could be hugely beneficial for future generations. The first gene-edited babies have already been born in China.

While these developments in CRISPR haven’t happened yet, we are likely to see these breakthroughs during our lifetimes.

Learn more about CRISPR gene editing from BioTechniques.

About BioTechniques

Since publishing its first issue in 1983, BioTechniques has upheld an acclaimed reputation as the journal that focuses on lab methodologies and reproducibility instead of treatments. It is these techniques and their repeatability that are essential to medical and scientific progression, yet are often overlooked. Over the past 40 years, BioTechniques has curated extensive coverage of lab methods like CRISPR gene editing, western blotting, next-generation sequencing, chromatography, and polymerase chain reaction (PCR), both in its print journal and on its website. 

The BioTechniques website holds a vast selection of free resources, from podcasts, videos, and webinars to articles, eBooks, interviews, and infographics. Scientists, lab workers, and research professionals from a variety of disciplines, such as physics, chemistry, computer science, and plant and agricultural science, use these resources to keep up with changes in the life sciences industry.