CRISPR: The Future of Gene Editing

Meera Singhal
7 min readMay 6, 2021

For the past two decades, ZFNs have been ruling the gene-editing field. Recently, TALEN took the throne from ZFNs, but TALENs reign was short-lasting compared to ZFNs. Before we dive into the future, let us have a quick history lesson on ZFNs and TALEN.

For over the past decade, zinc finger arrays have been one of the front-runner technologies for gene editing, targeting enzymes, and many other such protein domains (that are specific to a DNA sequence). Through this process, scientists have identified a huge number of zinc finger nucleases hat can recognize various nucleotide triplets. With some trial and error, zinc finger arrays are able to recognize a variety of nucleotide triplets. With years of trial and error, zinc finger arrays are now able to recognize their targets with a high accurate and specificity rate. Fifteen years of research has indicated to scientists that when zinc fingers are fused to a nucleases or activation domain. A zinc finger array is an effective targeting mechanism for molecular tools. Zinc fingers however do have some drawbacks. Not every nucleotide triplet has a corresponding zinc finger, and interactions between zinc fingers within an array can reduce their specificity.

Recently, a new form of gene editing has disrupted this field. Scientists call it TALEN, or more commonly known as Transcription activator-like effector nucleases. When TALEN was first introduced to the world way back in 2018, the biology field was shaken. Dan Voytas, the cofounder of TALEN and the Professor of Genetics, Cell Biology, and Development at the University of Minnesota. He introduced it to the world during this conference at Stanford. Enough of the history, lets talk about the future of CRISPR!

. In my mind, I like to think of CRISPR with an analogy. For example, take a working document. In a document, if I suspected that I misspelled a phrase or word, we can always use the find and replace bar to fix any errors. We can edit, delete add, basically just alter the words we wrote. Similarly, in our DNA, we have the same function. This function is taken on by a system called CRISPR Cas9.

CRISPR is short for;

Clustered

Regularly

Interspaced

Short

Palindromic

Repeats

CRISPR consist of two main components. The Cas9 protein has the ability to cut through DNA and a guide RNA that can recognize the sequence of the DNA that must be edited.

To use CRISPR Cas9, scientists first identify the sequence of the human genome that is causing a health problem. Then they create a specific guide RNA to recognize the specific strands of A, C, G, and T’s in the DNA. The guide RNA is attached to the DNA cutting enzyme Cas9. After that, this complex is introduced to the target cells. It locates the target letter sequences and cuts the DNA. At that point, scientists can then edit the existing genome by modifying, deleting, or adding new sequences (just like a word document!). This process efficiently makes CRISPR Cas9 an efficient cut-and-paste tool for DNA editing. In the future, scientists hope to use CRISPR Cas9 to develop critical advances in patient care or even cure lifelong diseases.

This is an incredibly high-level overview to teach yawl the basics, but its time to jump into the deep end. Inspired by this video, I will try to explain CRISPR on 4 different levels, a child, a teen, a college student, and an undergrad.

CRISPR is a new area of biomedical sciences. CRISPR enables gene editing to be a reality and it is currently helping us understand the genetic basis of many types of diseases like Parkinson’s, autism, or even cancer! Let us start with a base overview of CRISPR or explaining it to a child.

CRISPR is a tool that scientists are using to edit or change genomes. Genomes are like an instruction manual that make you, you! There can be mistakes however in this manual, and because of these mistakes, people can get sick, have allergies, or just have a genetic change in their body. CRISPR enables us to erase, change, or add different things to the big instruction manual.

Next, lets get a bit more complicated. In a sentence CRISPR is used to edit the genome (or DNA). DNA is the kind of language that the genome is written in and the genome itself is an instruction manual that describes how to make you. It gives you different biological characteristic, like how tall you are, your eye color, etc. An easy way to think about CRISPR is through an analogy. CRISPR is like a molecular pair of scissors that can go through your genome, find specific places in your genes, and make small (or big) alterations to your DNA.

Continuing this deep dive, lets move onto a college student. CRISPR is where you have a Cas-9 protein along with a guide RNA, and the guide RNA will basically tell the Cas-9 protein where to go, what to do, etc. This mechanism makes the CRISPR system much more programable than the other types of gene editing systems.

Moving even further into CRISPR, we have the undergrad student. Instead of going over how to describe CRISPR, I thought we could start with the ethics of CRISPR. There are many aspects of ethics that need to be taken into account while discussing the ethics of CRISPR. First, its important to clarify if we are using CRISPR in somatic cells (like T-cells) or if we are using it in embryo or germ stem cells. If you were to edit germline stem cells the effects of those edits would carry on for generations, even if they were unintentional. Furthermore, the issue of consent comes into play here. Secondly, CRISPR is a powerful tool. If it falls into the wrong hands, it can and will become very dangerous.

Now that you (hopefully) have a better understanding of CRISPR and its ethics, lets get into modern day examples of how CRISPR is being used to change the world. CRISPR is in the spotlight, and it is shining like a star. Here are my top 5 uses of CRISPR today!

- Inspired by this article, scientists were able to use CRISPR in lactic acid bacteria! Lactic acid bacteria are a phenotypically and phylogenetically diverse group that is found in many different types of natural environments. The widespread use of lactic acid bacteria across these industries fuels the need for new and functionally diverse strains that may be utilized as starter cultures or probiotics. Originally characterized in lactic acid bacteria, CRISPR-Cas’s systems and derived molecular machines can be used natively or exogenously to engineer new strains with enhanced functional attributes. Research on CRISPR-Cas’s biology and its applications has exploded over the past decade with studies spanning from the initial characterization of CRISPR-Cas’s immunity in Streptococcus thermophilus to the use of CRISPR-Cas for clinical gene therapies.

- This article inspired scientists to use CRISPR for viruses; in plants! CRISPR Cas-9 can not only be deployed in humans, but they can be used to model plants and crops for the control, monitoring, and study of different mechanical aspects of plant virus infections. Cas’s endonucleases can be used to engineer plant virus resistance by directly targeting viral DNA or RNA, as well as they can inactivate host susceptibility genes. Additionally, other applications of CRISPR/Cas in plant virology such as virus diagnostics and imaging are reviewed.

- This article inspired the uproar of CRISPR in plants (as you can see from the example above), represents the impact CRISPR has on agriculture and plant life in general. CRISPR Cas-9 in prokaryotes has an adaptive immune system that can naturally protect cells from any type of DNA virus infection. CRISPR-Cas9 has been modified to create a versatile genome editing technology that has a wide diversity of applications in medicine, agriculture, and basic studies of gene functions. CRISPR-Cas9 has been used in a growing number of monocot and dicot plant species to enhance yield, quality, and nutritional value, to introduce or enhance tolerance to biotic and abiotic stresses, among other applications. Although biosafety concerns remain, genome editing is a promising technology with the potential to contribute to food production for the benefit of the growing human population.

- This article truly proves that CRISPR has no bounds to its greatness. Scientists have been testing new ways CRISPR Cas-9 and other genome editing tools can battle cancer! Genome editing is a powerful tool, and they believe alongside ZFNs and TALEN, we can beat cancer in all patients. Read more in the article above!

- Inspired by this article, scientists have pushed the bounds of medical research once again. CRISPR/Cas9-mediated genome editing might provide novel strategies for cancer immunotherapy. Recently, the first-in-patient clinical trial was successfully performed with CRISPR/Cas9-modified human T cell therapy.

TLDR

- ZFN + TALEN. An overview of the older genome editing technologies.

- What is CRISPR? An overview + analogy to wat CRISPR really is.

- CRISPR on 4 levels. Explaining CRISPR on 3 different levels + talking about ethics.

  • Applications of CRISPR. 5 incredible examples of CRISPR since 2021!

Hello! My name is Meera Singhal, and I am a 13-year-old currently fascinated by the field of biotechnology, specifically stem cells and gene editing. I’ve written articles about biotechnology, mindset tips, and a whole variety of up-and-coming topics. Interested? Check out my medium, LinkedIn, YouTube, or TKS Life Portfolio for more content! Curious to see more about me? Consider subscribing to my Newsletter! Thank you so much!

--

--

Meera Singhal

Biotech Enthusiast at TKS | Stem Cells | Gene Editing