Editing our Genetic Code
Our bodies are essentially just giant computers.
Every single thing that our body does comes from the code stored inside our cells; without our program, we wouldn’t be able to function. If we change the code, it can affect how we look. It’s kind of like editing a video game character.
However, sometimes typos and errors occur in our code. In terms of normal computer programming, it usually causes the program to be unable to be executed. We simply go back, fix the error and run the program again. However, it can become a fatal mistake when a human’s genetic code contains an error. These typos are what generally cause genetic diseases, and for the longest time, we couldn’t do anything about them.
And now we can!
Introducing CRISPR-Cas9 🧬
In a nutshell, CRISPR-Cas9 is a leading technique that allows for precision edits to DNA.
CRISPR, or Clustered Regularly Interspaced Short Palindromic Repeat is a short, repetitive sequence of DNA code often found in the genomes of bacteria and other microorganisms. It’s a crucial part of the organisms’ immune systems which can thwart viral infections by destroying the invader’s genetic code.
So, how does this all help us?
Well, these CRISPR sequences are transcribed into short RNA sequences (called “CRISPR RNAs” or “crRNAs”) that can guide the system to match the sequences of DNA. When the target DNA is found an enzyme produced by the CRISPR system — Cas9 — binds to the DNA and cuts off the targeted gene. Now scientists can use a modified version of the enzyme to insert new gene expressions instead of just cutting off parts.
CRISPR-Cas9 sounds like something straight out of science fiction, but what if I told you that scientists found an even more efficient gene-editing technique?
Enter CRISPR-Cpf1.
What is CRISPR-Cpf1? 🦠
While scientists were searching different types of bacterial genome databases to look for sequences similar to Cas9 when they found Cpf1, a protein present in some bacteria with CRISPR. While both have a similar method, CRISPR-Cpf1 differs in several important ways from the previously described Cas9, with significant implications for research and therapeutics.
First, in its natural form, Cas9 forms a complex with two small RNAs, both of which are required for the cutting activity. The Cpf1 system is simpler in that it requires only a single RNA. The Cpf1 enzyme is also smaller than the standard SpCas9, making it easier to deliver into cells and tissues.
Second, and perhaps most significantly, Cpf1 cuts DNA in a different manner than Cas9. When the Cas9 complex cuts DNA, it cuts both strands at the same place, leaving ‘blunt ends’ that often undergo mutations as they are rejoined. With the Cpf1 complex, the cuts in the two strands are offset, leaving short overhangs on the exposed ends. This is expected to help with precise insertion, allowing researchers to integrate a piece of DNA more efficiently and accurately.
Third, Cpf1 cuts far away from the recognition site, meaning that even if the targeted gene becomes mutated at the cut site, it can likely still be re-cut, allowing multiple opportunities for correct editing to occur.
Lastly, the Cpf1 system provides new flexibility in choosing target sites. Like Cas9, the Cpf1 complex must first attach to a short sequence known as a PAM, and targets must be chosen that are adjacent to naturally occurring PAM sequences. The Cpf1 complex recognizes very different PAM sequences from those of Cas9. This could be an advantage in targeting, for example, the malaria parasite genome and even the human genome.
Applications of CRISPR
In Medicine 💊
CRISPR-Cas9 has so much potential to help kickstart the next medical frontier. It has the potential to fix the typos in our genetic code which causes genetic diseases once and for all. Now diseases which we had no power over can suddenly be obstructed, and maybe even completely cured!
Illnesses scientists are currently looking using CRISPR to cure are malaria, cancer, HIV, and so much more. Almost anything that stems from an “error” in our genetic code could potentially be solved using this technique.
In Agriculture 🌱
We can use CRISPR to edit the genes of our food and create genetically modified organisms, or GMOs. This can help make longer-lasting produce, more nutritional foods, and also protect foods from pesticides and possible infestations. These all contribute to our attempt to make agriculture a much more efficient industry — for every crop of plants farmers are sure to harvest almost perfect crops thanks to the preventions put in place against pesticides and bugs, and since they have longer shelf lives grocery stores can keep the food for much longer. With the worsening of climate change and overpopulation threatening everyone, this is an especially important advancement for the world.
The genetic editing of plants may also become a crucial part of the fight against climate change. Currently, scientists are looking into ways to genetically modify plants to increase their carbon-capture concentration thus removing excess carbon from the atmosphere.
There are so many potential applications for gene editing, we just have to find them!
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