CRISPR/Cas9 Screening Technology on Drug Identification

By Elif Hangül

It has been claimed that genetic engineering is like nuclear science, as both confer a power on humans for which they are psychologically and morally unprepared.

D. R. J. MACER

What is the perfect future for you?

Imagine a world where every human being has the potential for a healthier life, where diseases have met their match, and where perfection is within reach. It might sound like a dream, but it’s not as far-fetched as you might think. This is the intriguing realm of CRISPR technology, a revolutionary scientific advancement that’s changing the way we look at genetics and healthcare. Let’s dive into the fascinating world of CRISPR and explore its promise and potential implications.

For many years, researchers dedicated themselves to the pursuit of developing accessible and cost-effective genome editing tools capable of addressing diverse challenges across various fields. Their relentless efforts culminated in the breakthrough known as CRISPR, a powerful molecular tool capable of editing DNA at nearly any location. Due to its user-friendliness and versatility, CRISPR has already found application in a wide range of fields, sparking hope for a promising future.

What is CRISPR/Cas9?

In the realm of genetics and medical research, CRISPR-Cas9 stands as an extraordinary tool, allowing scientists to modify segments of our genetic code. It can perform tasks such as deletion, addition, or alteration of specific sections within our DNA sequence. This revolutionary technique has garnered significant attention within the scientific community due to its unparalleled simplicity, versatility, and precision.

So, how does this groundbreaking technology operate?

The CRISPR-Cas9 system comprises two essential components, working in tandem to bring about genetic changes:

1. Cas9, the Molecular Scissors: First, there’s Cas9, an enzyme that functions like a pair of tiny “molecular scissors.” It excels at making precise cuts in the two strands of DNA at predetermined locations within the genome. These cuts pave the way for the addition or removal of specific DNA segments.
2. Guide RNA, the Precision Navigator: Then, there’s the guide RNA (gRNA), a remarkable piece of genetic machinery. It consists of a small RNA sequence, around 20 bases long, nestled within a longer RNA scaffold. The scaffold part plays a crucial role by binding to the DNA, while the pre-designed sequence within the gRNA serves as a beacon, guiding Cas9 to the exact spot in the genome that requires modification. This strategic pairing ensures that Cas9 snips the DNA at precisely the right location.

Here’s where the real magic happens: the guide RNA is meticulously engineered to locate and attach itself exclusively to a specific sequence within the DNA. It’s a bit like a genetic detective, with RNA bases that perfectly complement those of the target DNA sequence. This means that, in theory, the guide RNA will only adhere to the intended target sequence, leaving the rest of the genome untouched.

Once guided to the correct location, Cas9 swings into action, slicing across both strands of the DNA, creating a break.

At this point, the cell recognizes that its DNA has been tampered with and sets out to repair the damage. Here’s where scientists seize the opportunity: they harness the cell’s DNA repair machinery to introduce alterations to one or more genes within the genome of a specific cell of interest.

What is Screening Technology?

In this article, I will be talking about an application of CRISPR, Screening Technology, aka Genetic Screens.

Functional genetic screens are like powerful tools that help scientists understand how genes influence biological processes in a big-picture way. They work by making lots of changes to genes across the entire genome, which is like our genetic instruction manual. These changes help scientists come up with ideas about which genes might be linked to normal processes or diseases. To confirm these ideas, scientists do more tests and experiments.

There are two main ways to change genes in these screens: one is to make them work more, and the other is to make them work less. When genes work more, they make more of their products, like proteins or RNA. When genes work less, they make less of these products or stop working altogether. Scientists look at what happens to the biological process or disease when they do this.

Genetic Screens in Drug Discovery

Genetic screens are like detectives in the world of drug discovery, helping researchers find potential compounds to treat diseases. In this process, scientists aim to pinpoint specific genes that are connected to a disease. These genes become the “targets” for developing new drugs.

There are many ways to discover these potential targets, like searching through biomedical research and clinical studies. However, loss-of-function (LOF) screens are often the heroes of the story. Imagine this: by using LOF screens with healthy cells, scientists can find genes that, when switched off, recreate the features of a disease. It’s like finding the gene responsible for making the trouble in the first place.

On the other hand, if you have cells from a sick person (for example, in cancer), and by making genetic changes, you make them act normal again, it’s like mimicking the effect of a potential drug. These screens can reveal genes that either make diseases worse or better, or they might uncover entirely new members of the disease’s “team.”

In short, LOF screens are a crucial part of the journey to find new drugs to fight diseases. They help scientists identify the culprits and potential heroes in the fight against illnesses.

CRISPR has emerged as an incredibly useful tool in the world of genetics. It allows scientists to make very precise changes in genes, helping them understand how these changes affect observable traits, which we call phenotypes. This technique, particularly CRISPR loss-of-function (LOF) screens, has become a common practice in the search for potential drug targets across various diseases.

Finding the right drug is like building a house; you need a solid foundation. Effective drug discovery starts with identifying the right target, and this is where CRISPR comes in. It’s a bit like detective work: scientists use CRISPR to turn genes off in a very specific way and then observe what happens. If the gene they switched off is connected to a disease, this could be a potential drug target. This step is crucial for the successful development of new medications.

There are two main types of screens when using CRISPR: pooled and arrayed. Pooled screens use a method involving viruses and are mainly good for checking simple traits — it’s a bit like a yes or no answer. On the other hand, arrayed screens are more versatile. They can be used with different methods and can tell you more complex things about cells. This second method is becoming increasingly popular because it provides a wealth of biological information.

Synthego, a company at the forefront of this field, has combined the strengths of arrayed screens with multi-guide design technology in their Screening Libraries. These libraries are like toolkits for scientists, helping them make very reliable gene knockouts. Whether you’re exploring standard or custom screening libraries, Synthego’s tools can quickly help you assess potential gene targets, making your journey through drug discovery a confident one.

The Advantages

Imagine scientific research as a detective case. You’re searching for clues, but instead of fingerprints, you’re dealing with genes. These genes hold the secrets to diseases and traits. But here’s the catch: you can’t just grab all the genes in the room; you need to pick them out one by one with tweezers. That’s where screening technology enters the scene, like your trusty detective assistant.

Efficiency is its middle name. It’s like having a super-speedy partner who can process a mountain of evidence in no time. In the old days, it would be like investigating each piece of evidence separately, taking forever. Now, with screening, it’s like having a turbocharged magnifying glass.

But it’s not just about speed; it’s about precision too. Without screening, it’s like searching for a needle in a haystack wearing oven mitts. Screening gives you the precision of a laser-guided needle finder — you can pluck out exactly what you need.

Screening is versatile, like your favorite multitool. It doesn’t matter if you’re solving the mystery of cancer, Alzheimer’s, or the flu. It’s your go-to gadget for all things genetic.

And it’s not just about finding genes; it’s about understanding how they work. It’s like deciphering the recipe for a magic potion. With screening, you can say, “Gene A does this, and when you mix it with Gene B, you get that!”

Plus, screening generates massive amounts of data. It’s like having a supercomputer analyze all the evidence, finding patterns and connections that would take forever to spot by hand.

But here’s the real deal: it’s not just a detective game; it’s about saving lives. Screening helps identify those critical genes that could become the heroes in the fight against diseases. It’s like discovering a treasure map that leads to a cure.

And here’s the best part: screening does all this without harming any lab animals. It’s like solving the case without any innocent bystanders getting hurt.

So, that’s screening technology — your trusty detective sidekick in the world of genetics. It’s efficient, precise, versatile, and it uncovers the secrets that could change lives for the better. It’s like being a detective but with genes instead of clues.

Limitations

Screening technology, while immensely valuable, does come with its set of limitations that researchers need to consider. These limitations can be divided into several key areas:

1. Complexity of Biological Systems: The biological world is incredibly complex. While screening allows us to manipulate genes and study their effects, it often oversimplifies the intricate interactions within living organisms. Biological systems involve countless genes, proteins, and regulatory mechanisms, making it challenging to capture the full complexity.

2. Off-Target Effects: Despite advancements in precision, screening techniques like CRISPR may still result in unintended genetic changes. These off-target effects can lead to false conclusions, potentially diverting research down the wrong path. Ensuring specificity remains a significant challenge.

3. Lack of Real-World Context: Screening is typically performed in controlled laboratory settings, which may not fully represent the complexities of the real world. Cellular responses observed in vitro may differ from those in living organisms, impacting the relevance of findings.

4. Incomplete Understanding of Genes: Our understanding of gene function is incomplete. While we’ve made great strides, there are many genes with unknown functions. Screening can only uncover what we already know or suspect, potentially missing entirely novel genes that play crucial roles.

5. Limited Phenotype Observation: Screening often focuses on observable cellular or molecular phenotypes. This means that certain aspects of gene function, such as long-term effects or subtle changes, might be overlooked. Some effects might only become apparent over extended periods, making them challenging to detect in short-term screens.

6. Ethical and Safety Concerns: The power to manipulate genes raises ethical concerns, particularly regarding germline editing. Safety is also a concern, as unintended genetic changes could have unforeseen consequences, both in research and potential clinical applications.

In the captivating realm of genetics, CRISPR stands as a mighty hero, wielding the power to unlock the secrets of our DNA. It’s a tool that lets researchers dive deep into the genetic code, connecting changes in traits (those are the phenotypes) to specific gene knockouts. Picture it like having a magic wand that can pinpoint the exact genes responsible for certain traits — a wizardry of science!

CRISPR isn’t just a one-time wonder; it’s become the go-to companion in the quest for new medicines. These days, you’ll find CRISPR-powered Loss-of-Function (LOF) screens as regular guests in the world of drug discovery. These screens are like treasure maps, leading us to potential drug targets across a wide range of diseases. Finding the right drug target is like discovering the buried treasure at the end of a quest — it’s the essential first step in the epic journey of drug development.

Now, let’s talk about screens — the different flavors, if you will. There are two types: pooled and arrayed. Pooled screens are like detectives looking for a simple yes-or-no answer using viral tricks. They’re good for figuring out the basics. On the other side, we have arrayed screens, which are like Sherlock Holmes. They can use various methods to delve into the complex aspects of cells. This approach is gaining popularity because it’s like getting a rich, full-color picture of the biological landscape.

In the grand tapestry of genetics, CRISPR and its screening companions are the artists, painting the vivid portraits of genes, diseases, and potential cures. They’re the architects of our future medicines, setting the foundation for healthier, brighter tomorrows.