Revolutionising the CRISPR method

Revolutionising the CRISPR method
Genes and proteins in cells interact in many different ways. Each dot represents a gene; the lines are their interactions. For the first time, the new method uses biotechnology to influence entire gene networks in one single step. Credit: ETH Zurich/Carlo Cosimo Campa

Everyone's talking about CRISPR-Cas. This biotechnological method offers a relatively quick and easy way to manipulate single genes in cells, meaning they can be precisely deleted, replaced or modified. Furthermore, in recent years, researchers have also been using technologies based on CRISPR-Cas to systematically increase or decrease the activity of individual genes. The corresponding methods have become the worldwide standard within a very short time, both in basic biological research and in applied fields such as plant breeding.

To date, for the most part, researchers could modify only one gene at a time using the method. On occasion, they managed two or three in one go; in one particular case, they were able to edit seven genes simultaneously. Now, Professor Randall Platt and his team at the Department of Biosystems Science and Engineering at ETH Zurich in Basel have developed a process that—as they demonstrated in experiments—can modify 25 target sites within genes in a cell at once. As if that were not enough, this number can be increased still further, to dozens or even hundreds of genes, as Platt points out. At any rate, the method offers enormous potential for biomedical research and biotechnology. "Thanks to this new tool, we and other scientists can now achieve what we could only dream of doing in the past."

Targeted, large-scale cell reprogramming

Genes and proteins in interact in many different ways. The resulting networks comprising dozens of genes ensure an organism's cellular diversity. For example, they are responsible for differentiating progenitor cells to neuronal cells and immune cells. "Our method enables us, for the first time, to systematically modify entire gene networks in a single step," Platt says.

Moreover, it paves the way for complex, large-scale cell programming. It can be used to increase the activity of certain genes, while reducing that of others. The timing of this change in activity can also be precisely controlled.

This is of interest for basic research, for example in investigating why various types of cells behave differently or for the study of complex genetic disorders. It will also prove useful for cell replacement therapy, which involves replacing damaged with healthy cells. In this case, researchers can use the method to convert stem cells into differentiated cells, such as neuronal cells or insulin-producing beta cells, or vice versa, to produce stem cells from differentiated skin cells.

The dual function of the Cas enzyme

The CRISPR-Cas method requires an enzyme known as a Cas and a small RNA molecule. Its sequence of nucleobases serves as an "address label," directing the enzyme with utmost precision to its designated site of action on the chromosomes. ETH scientists have created a plasmid, or a circular DNA molecule, that stores the blueprint of the Cas enzyme and numerous RNA address molecules, arranged in sequences: in other words, a longer address list. In their experiments, the researchers inserted this plasmid into human cells, thereby demonstrating that several genes can be modified and regulated simultaneously.

For the new technique, the scientists did not use the Cas9 enzyme that has featured in most CRISPR-Cas methods to date, but the related Cas12a . Not only can it edit , it can also cut the long "RNA address list" into individual "address labels" at the same time. Furthermore, Cas12a can handle shorter RNA address molecules than Cas9. "The shorter these addressing sequences are, the more of them we can fit onto a plasmid," Platt says.


Explore further

A novel method to characterize genes with high-precision in single cells

More information: Carlo C. Campa et al, Multiplexed genome engineering by Cas12a and CRISPR arrays encoded on single transcripts, Nature Methods (2019). DOI: 10.1038/s41592-019-0508-6
Journal information: Nature Methods

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Citation: Revolutionising the CRISPR method (2019, August 14) retrieved 18 August 2019 from https://phys.org/news/2019-08-revolutionising-crispr-method.html
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Aug 14, 2019
"biotechnological" ??? Really??? My god! You are an adult, right? How about something simpler like "biotechnic"?

Aug 14, 2019
My own thought is -
By increasing the complexity of the process, they increase the negative probabilities of the result...

Aug 14, 2019
This is the spectacular future of mankind. Guided evolution. Mankind version 2.0
While stem cell therapy is really great and a up and coming thing that will lead to many cures and tissue regrowth, genetic engineering is the be all, end all of human advancement.
It makes no difference whether your for it or against it, genetic engineering is progress and no one has stopped progress in the history of the human race. Occasionally temporarily slowed progress but never stopped progress.
The greatest achievement of mankind will not be space travel, immortality, fusion etc. Man's greatest achievement will be using genetic engineering to increase EVERYONE'S intelligence 5 fold or even greater.
There are plenty of conspiracy theorists that will find the dark side of this and others that say we will become monsters etc.
If I snuck a liquid in your milk that would raise your intelligence by 20% would you know it tomorrow? NO, you would just be a little sharper. not turn into a monster.

Aug 15, 2019
You are an adult, right? How about something simpler like "biotechnic"?


More mature than you that reacts on terminology - and the most used one. with a factor 10, at that: https://www.googl...ie=UTF-8 444 000 results
https://www.googl...ie=UTF-8 5 430 000 results.

Aug 15, 2019
@rderkis: " Guided evolution. ... increase ... intelligence".

No, and not likely.

At best, if these methods can ever be used except against unwanted variation, which is unlikely (due to the still high error rate vs the number of body cells) but possible, they would give new variation in some individuals. It is unlikely, but possible that selection or drift would fix them, you would need a high mutation rate to get a decent likelihood for a given mutation fixation. I.e. it would cost and you would need a popular allele change. It is not guided, and it is hardly evolution - selective breeding is a much better example.

Intelligence is, as the majority of traits, multifactorial. Good luck with changing any of those, you have better luck continuing to smoke that pipe you seem to be using! (O.o)

Aug 15, 2019
Intelligence is, as the majority of traits, multifactorial. Good luck with changing any of those, you have better luck continuing to smoke that pipe you seem to be using! (O.o)


Don't feel bad about your lack of vision of the future. Your right, man will never be able to make fire, fly, kill at a distance, cure any disease except by magic and on and on. At one time the majority of people felt exactly as you do about those achievements, to the extent they would bet their lives on it. And kill anyone that disagreed with those beliefs.
Besides I can tell by your last sentence you both lack a education and like to try to bully people.

Aug 15, 2019
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Aug 16, 2019
"The shorter these addressing sequences are, the more of them we can fit onto a plasmid," Platt says.


The shorter the addressing sequence is, the higher the likelihood that it will also match to other areas that are not being targeted. Think of it as a wildcard search - the more characters you enter in to the search box, more likely you are to get the result you wanted. With lesser characters you get more search matches that aren't the ones that you intended.

Aug 16, 2019
This is the spectacular future of mankind. Guided evolution...

If I snuck a liquid in your milk that would raise your intelligence by 20% would you know it tomorrow? NO, you would just be a little sharper. not turn into a monster.


Agreed. Guided adaptation/evolution may be the only way we can establish ourselves on other planets within short (centennial) timeframes. The promise of techniques like CRISPR is that they can be effective in a short time in an adult - the science fiction scenario of getting a shot, getting a fever, waking up to find your skin photosynthesizing is not too far fetched.

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