Multiple single-base editing techniques have a large number of RNA off-target, providing the basis for single-base technology to enter clinical treatment.

Recently, the international top academic journal Nature published online, "DNA monobase editing technology caused RNA (ribonucleic acid) off-target and its mutation elimination of RNA activity" research paper, for the first time proved that a number of single-base editing technology have a large number of RNA off-target, and access to 3 more high-precision single-base editing tools, for single-base editing technology into clinical treatment provides an important basis.
three months later, the results of the Yang Hui Research Group of the Center for Excellence in Brain Science and Intelligent Technology of the Chinese Academy of Sciences once again appeared in nature, the world's top academic journal.
this time, the "post-85" researcher led his team, all the way to the thorns, the first evidence that a number of single-base editing techniques are a large number of RNA off-target, and access to three more high-precision single-base editing tools, for single-base editing technology into clinical treatment provides an important basis.
" this study provides a single base editor to reduce RNA off-targeting and is of great value in the field of gene editing.
" international peers such as evaluation.
's magical single-base editing technology with the continuous progress of science and technology, gene editing, once high on the scientific term, has now entered the public eye.
" gene editing technology, if used properly, can benefit mankind.
" Yang Hui, for example, using this technique, we can improve plant traits to make vegetables have a longer shelf life and taste better, and the resuscitation of extinct species through related DNA is not out of reach.
, of course, the more critical thing for gene editing technology is to treat some malignant diseases.
myelin muscular dystrophy, thalassemia, haemophilia, retinal macular degeneration, hereditary deafness... According to Yang Hui, there are 300 million rare cases worldwide, half of them children.
the vast majority of these 7,000 rare diseases have no effective drugs to treat, like a sword hanging over the head of the Damocles, which has long plagued humans.
single-base editing technology, like a dawn, gave scientists and patients hope.
"80% of rare diseases are monogenous.
thetheory, more than 50% of single-gene genetic diseases can be repaired by single-base editing technology.
" the first author of the paper, the Chinese Academy of Sciences Institute of Neurology doctoral student Zhou Changyang said.
the reality, however, is that, as safety has been uncertain, so far, only two or three gene-editing techniques have entered clinical trials.
is an invisible mountain in front of the rare disease patients.
genes are fragments of DNA that have a genetic effect.
human DNA consists of more than 3.1 billion base pairs, which are organically arranged organically by atCG.
so-called gene editing, that is, the genome of specific DNA fragments to knock, join, replace and so on.
2012, crispR/Cas9, a third-generation gene-editing tool, quickly gained popularity in the scientific community, thanks to its low cost, ease of operation and high efficiency.
on the basis of CRISPR/Cas9, and then derived a fourth generation of gene editing technology - single-base editing technology: a class of CBE, i.e. a type of editor that can convert C mutations from four nucleotides of DNA into T or G into A, and a second aBE, which is an editor that can convert T-mutations into C or A into G.
" gene-editing tool CRISPR/Cas9 is the equivalent of a pair of scissors with GPS.
" as the research deepened, Zhou Changyang and others found that in the process of repairing many diseases, because CRISPR/Cas9 first needs to cut off the DOUBLE strand of DNA, and then use the cell's own repair to repair accurately, which often leads to the cutting off of the DNA double-stranded, only a part of the cells will be repaired through precise homologous recombination, and the other part will be repaired randomly.
and random repair often causes other mutations, which limits the application of CRISPR/Cas9 technology in disease treatment.
"If CRISPR/Cas9 and its derivatives are used in clinical practice, off-target effects can cause a variety of side effects, including cancer."
," Yang said.
single-base editing techniques can modify DNA more finely than CRISPR/Cas9.
"single-base editing technique can accurately detect directed mutations of DNA without cutting off the double strand of DNA, which can be applied to most monogene genetic diseases.
," Zhou Changyang said.
the ubiquitous risk of off-targeting we know that, in some extreme cases, changes in a base can lead to changes or deletions in certain genes, which can lead to disease.
in fact, nearly half of all single-gene genetic diseases in humans are caused by a base change.
therefore, whether this particular base can be safely and effectively repaired is an important mission of gene editing tools.
"No matter which gene editing tool, editing efficiency and specificity have been two key factors in measuring their good or bad."
" Zhou Changyang said, gene editing technology is difficult to develop, not only to ensure a high efficiency of target site editing, but also to ensure the specificity of gene editing tools.
in other words, our gene editing tool can only edit destinations, not to other sites that they don't want to edit.
ideal is very plump, the reality is very bone.
With the further research, since the birth of CRISPR/Cas9 technology, single-base editing, a high-precision gene-editing technique that the scientific community has highly anticipated, was also proved difficult to escape the risk of targeting earlier this year.
earlier this year, Yang Hui's team established a new off-target detection technology called GOTI, which, through sophisticated experimental design, found that the original lysic CBE monobase gene editing technology had DNA off target, the probability of off-target is equivalent to 20 times the natural genetic mutation.
What does it mean? "If off-target occurs on cancer genes and cancer-suppressing genes, it will lead to a certain risk of cancer.
" Zhou Changyang explained.
thanks to the discovery, two companies are pushing clinical lying on two gene drug projects that were halted in time.
the pace of exploration did not stop there.
, research on single-base editing technology has been focused on DNA levels, does the tool also have a risk of off-targeting at RNA levels? Aiming at the new target, Yang Hui team began a new round of in-depth research.
more secure and accurate editing tools.
this time, the research team extended the range of single-base editing technology off-target detection to RNA levels, the first evidence of the commonly used three single-base editing techniques BE3, BE3-hA3A and ABE7.10 have a large number of RNA off-target, and found that ABE7.10 high frequency occurred in cancer genes and anti-cancer genes, with a strong risk of cancer.
", in previous studies, CBE monobase editing technology had a random target of DNA levels across the genome, and ABE monobase editing technology did not detect off-targeting of DNA levels.
our study found that both CBE and ABE were off target at RNA levels.
" Zhou Changyang told reporters that this suggests that the field needs to be concerned not only with the DNA level off-target examination of gene editing tools, but also about RNA level off-target examination. "Our original intention was to develop highly editing efficiency and highly specific gene-editing tools that can be applied to the treatment of diseases, "
.
," Zhou Changyang said.
it turns out that RNA off-target ingress does exist on a monobase editor, but what part of the RNA offtarget is caused by that? Using a sophisticated experimental design, the team found that deaminase found in the monobase editor was the "main culprit."
they performed mutation optimization on the cytosine deaminase of CBE monobase gene editing technology and ABE monobase gene editing technology, inactivated RNA binding activity of the two deaminases, so that they could not bind to RNA, and eventually obtained a high-fidelity monoyl editing tool that completely eliminated RNA offtarget and maintained DNA editing activity.
, the team developed a new generation of ABE single-base editing tools that can narrow the editing window for more accurate DNA editing.
the technology surpasses single-base editor ABE7.10 in terms of specificity and precision, and is expected to become a safer and more precise gene editing tool for clinical use in the future.
Zhou Changyang told reporters that the next step, the research team will strive to develop neither DNA nor RNA off-target editing tools.
how to make gene editing tools smaller and easier to import into patients' cells for treatment is also an important direction for future research.
now, the team has begun experimenting with gene-editing studies using the model of mice and monkeys to treat rare diseases.
Source: Economic Daily.