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30 Gennaio 2018

A precision Tool to remove Portions of DNA

Many had welcomed genome-editing as the most exciting discovery in 21st century biology for its impressive applications. Yet, since the beginning, the lack of accuracy of the DNA-editing enzyme made it impossible to use it effectively. CIBIO, the Centre for Integrative Biology of the University of Trento, has found a way to turn it into a precision tool that only targets a specific site of DNA that needs to be removed. In this way it will be possible to use genome-editing to correct sequences of genes, for example in patients with genetic disorders or cancer. The study, conducted in Trento, has been published in “Nature Biotechnology”

Anna Cereseto, senior author, commented: “The point of strength of the work is that we have developed a variant of the CRISPR/Cas9 molecule that is safer and more reliable than any other described so far, which is capable of cutting exactly where we want it to”. The objective now is to make the most of the patent that has been filed for the invention with positive outcomes at local level

A new phase of genome editing has started. The method through which it is possible to modify DNA for therapeutic purposes, originally devised and developed in Berkley and at the MIT in Boston, became reliable and safe to use in clinical setting on the hill of Trento. And this turning point, an achievement of the Centre for Integrative Biology - CIBIO of the University of Trento, may soon have positive effects for the gene therapy that is used to treat certain disorders.
“We have devised an experimental screening method through which we have obtained a molecule, called evoCas9, which is extremely accurate in editing DNA. This enzyme, which is able to target only a specific point, is absolutely reliable”, proudly commented Anna Cereseto, professor at CIBIO and senior author of the article that describes the study in “Nature Biotechnology”, the bio-medicine journal with the highest impact factor in the field.
“The molecule we started from, CRISPR/Cas9, is changing biomedicine. It is a “molecular machine”, consisting in the Cas9 protein and an RNA molecule, which reaches a specific segment of DNA and cuts a sequence. The problem is that this molecule is not enough accurate and when it is used in the treatment of diseases it does not modify only the gene or genes responsible for it but also affects other portions of DNA with unpredictable consequences. This makes it unsuitable for clinical applications. In this moment, our evoCas9 is the best molecular machine in the world for genome editing”, underlined Cereseto.
CIBIO therefore beats its competitors in the international science arena. “Genome editing is a great discovery for medicine and beyond», underlined Alessandro Quattrone, the director of CIBIO. “This invention by Anna Cereseto and her brilliant collaborators and colleagues has been so far the most important contribution we made to the development of medical treatments. The research group presented a smart solution to improve the method a few months ago. Then it was about a “disposable genomic scalpel”. But with evoCas9 we are making a real difference between a useful tool and a true game changer. Thanks to this study, which follows in the steps of the previous one, genome editing moves to a further stage and our efforts now are directed to create other growth opportunities, as far as possible, in Trentino. There is a global interest in this technology, that is why it is difficult to keep it here; we are working together to leverage on these achievements to create a local biotech industry capable of attracting capitals. The Province of Trento, which has always supported the University and the founding of CIBIO, deserves this”.
The first and most immediate application of EvoCas9, the “perfect editor”, is the treatment of genetic diseases and cancer, but it can also be used in other non-medical sectors where genome-editing has become essential: to improve plants and animals for human consumption, for example.
How was it possible to obtain this almost perfect molecule? Anna Cereseto explained that “evoCas9 has been developed as a Darwinian in vitro evolution of Cas9, that is why its name is evoCas9. Cas9 comes from bacteria, where its inaccuracy is an advantage because it works as a sort of immune system against foreign DNA as it succeeds to disable the enemy by cutting here and there. Our intuition was to create Cas9 from yeasts, non-bacterial cells which are simpler but also very similar to human cells. Here we made it become what we wanted it to be: a precision tool that only cuts where it is directed and is capable of targeting one specific site leaving healthy cells untouched. Thanks to this, its application in a clinical setting will be safe”.
In addition to the publications, a patent has been filed for evoCas9 and is attracting attention. In a few more months we will know if and how the future of evoCas9 will be written in Trento.
The authors
The article, “A highly specific SpCas9 variant is identified by in vivo screening in yeast”, has just been published in “Nature Biotechnology”.
The research study was entirely carried out by CIBIO at UniTrento and involved three research laboratories. The Laboratory of Molecular Virology with Antonio Casini (first author), Michele Olivieri, Gianluca Petris, Claudia Montagna, Giordano Reginato, Giulia Maule and Anna Cereseto (senior author and principal investigator). The Laboratory of Computational Oncology with Francesca Lorenzin, Davide Prandi, Alessandro Romanel and Francesca Demichelis (principal investigator). And the Laboratory of Transcriptional Networks with Alberto Inga (principal investigator)

The article, “A highly specific SpCas9 variant is identified by in vivo screening in yeast”, has just been published in “Nature Biotechnology” and is available in Open Access here: https://www.nature.com/articles/nbt.4066