Posted by on January 30, 2018 1:33 pm
Categories: Baidu

Source: gene editing 2. 0:classic the CRISPR system has been not enough

Sina science and technology news Beijing Time 1 November 29 message, according to foreign media reports, in less than 5 years, gene editing technology CRISPR has made the modern biology of the appearance and development of the rhythm occurred a revolutionary change. This technique can be found, remove and replace the genetic material, since 2012, the first reported so far, scientists have published more than 5000 articles relates to the technical papers. Biochemistry researchers to embrace this technology, hope to use it to create a better disease model. Numerous companies have put this technology into new drugs, therapies, food, compound and new material development, trying to acquire new business interests.

normally, when we refer to the CRISPR, the actual refers to the CRISPR/Cas system-consists of a small segment of RNA and a highly efficient DNA cutting enzymes namely nucleic acid enzymes composed of, full name is often between the palindromic repeats of the sequence clusters/inter-palindrome repeated sequence clusters associated with a protein system, clustered regularly interspaced short palindromic installed or support/CRISPR-associated proteins is. It is for the biological meaning, just like the Ford Model T car for the manufacturing industry and the transport industry meaning. Now, CRISPR has been used for human cancer treatment, and the fastest by 2018, the technology will also be used in hereditary diseases, such as sickle red blood cell disease and beta-thalassemia clinical trials.

however, with the original Ford Model T car, like the classic CRISPR technology has become a bit crude benzene, unreliable, and even a little dangerous. It failed with the genome of any binding site, sometimes cutting the wrong location. Moreover, it has no Close button. If the Ford Model T car was prone to overheating, that classic CRISPR can be said to be very easy to“eat more”.

even with such limitations, but the classic CRISPR system in 2018 and later days, and still is biologically a very important tool. However, in 2017, to update, faster gene editing tools to start soon, perhaps very soon will make the first generation of the technology overshadowed. Therefore, if you are interested in this field to show its mettle, then, please get ready, because“gene editing 2. 0”is at hand!

targeted cutting operation is CRISPR technology and iconic features. However, in the Cas9 endonuclease enzymes cut an organism of the two strands of the DNA chain at the same time, also will bring some kind of risk. targeted cutting operation is CRISPR technology and iconic features. However, in the Cas9 endonuclease enzymes cut an organism of the two strands of the DNA chain at the same time, will also bring some risks.


targeted cutting operation is CRISPR technology and iconic features. However, in the Cas9 endonuclease enzymes cut an organism of the two strands of the DNA chain at the same time, will also bring some risks. Cells in the repair of such severe genetic damage that may occur when an error. This is also the scientists hope to design a more secure method to achieve the same object of reason.

one method is to make a Cas9 nuclease mutant, loss of cutting ability, but still capable of binding DNA. Subsequently, other proteins-for example, can activate gene expression of protein-losing part of the function of Cas9 nuclease binding, without changing the DNA sequence of the case where the common control genes on and off, sometimes have to use light or chemical signals. This“epigenetic editing”might be used in the treatment of a variety of genetic factors common cause of the disease, and the classic CRISPR technology is the most suitable is by a single mutation leads to dysfunction of the problem. 12 in early May, the U.S. Salk Institute researchers in the mice on try this new method, to include diabetes mellitus, acute renal disease and muscular dystrophy and other serious diseases for treatment.

Harvard University and the Broadbent Institute scientists have even of the CRISPR system were more bold improved: a single base pair editing. In order to achieve this purpose, they must design a brand new, in the nature���Without the presence of enzymes capable of chemical will be the pairing of adenine,-thymine(T)transition of guanine(G)-cytosine(C)。 This change may seem tiny, but has a very significant meaning. Harvard University chemist David Liu David Liu presided over the work, he estimated that in the human body known to 32,000 pathogenic point mutations, had about half the CAN through such a single site conversion and repair.“ I don’t want the public to have the wrong understanding that we can turn anyone or any animal, and even Petri dish cell of any DNA fragment is converted into another piece of DNA,”David Liu said,“however, we are now at the position, also means a lot of responsibility. The biggest problem is that, this era can reach the capacity? And how we can as quickly as possible with these technologies to benefit society?”

how to control risk?

The CRISPR/Cas system is present in most bacteria and the majority of the archaea in one of the Acquired Immune mechanisms, which work is to discover the invasion of virus DNA and destroy, until the DNA is clean. This system is the“accelerator”, there is no braking device, which has a potential danger-especially in clinical applications. CRISPR in the cell retention time the longer, it take some segment as the target gene and cut the risk is greater.

In order to minimize these off-target issues, scientists have been developing new tools to better control CRISPR. As of now, researchers have identified the 21 naturally occurring anti-CRISPR anti-CRISPR protein family, i.e., capable of inhibiting gene editing enzyme protein molecule. However, scientists know only a few proteins of the working mechanism. Some proteins can be directly with Cas9 in combination, prevent it from connecting to the DNA; other proteins then can be activated with the Cas9 competitive genomic location of the enzyme. Currently, the University of California, Berkeley, University of California San Francisco, Harvard University, Broadbent Institute and the University of Toronto are working on the use of these natural closure mechanisms of the method, so that they can become encoded control tool.

In addition to the medical application, these protein families but also on“gene drive,”a gene drive the field of sustainable development has important significance. Gene-drive in 2003 by Imperial College London evolutionary geneticist Austin Burt, Austin Burt proposed, refers to a specific traits to quickly spread to the populations in the gene editing technology. If you can somehow push the evolution process will be very beneficial to the human response from pandemics to climate change and many other issues. For example, we can use this method to destroy those that cause malaria, the mosquitoes, or to remove harmful invasive species. However, in the wild environment, these means also it is possible to lose control, and even catastrophic consequences. In 2017, the United States Ministry of Defence’s defence Advanced Research Program DARPA is investing 6500 million dollars, for looking for safer gene-driven design, including anti-CRISPR“off switch.”

Cas enzyme progress

despite decades of gene technology by leaps and bounds, but there’s still a lot scientists don’t understand why the DNA of some of the defects will lead to disease. Even if we know which genes and in what order coding into the cell, but want to know these sequence of information on how to transfer, how translation or no translation, it is much more difficult. This is what Harvard University and the Broadbent Institute Zhang Feng CRISPR associated proteins found that one of the teams looking to RNA as the target of Cas enzyme reasons.

since the cells in the assembled protein to read the genetic information from the RNA, and therefore they carry more about the special diseases of the basis of genetic information. Moreover, since the RNA is continually being transcribed and translated, and therefore of RNA modifications contribute to a better treatment of a similar inflammation or trauma and other short-term diseases. This is a new system called“REPAIR”, the full name is“programmable adenine-to-inosine RNA editing”of RNA Editing for Programmable A to I Replacement, and is currently only a single nucleotide to be edited. Next, the researchers hope that in the other 11 possible combinations to try this technique.

scientists in fact have been foundThe new Cas of the enzyme. Broadbent Institute team for the nucleic acid enzyme Cpf1 characteristics were studied. This enzyme with other Cas enzymes have several key differences, including in the cutting of DNA will leave the more active end, rather than the“blunt”end. 2017 2 July, University of California, Berkeley research team found CasY and CasX, which is currently the most concise of the CRISPR system. The next few months or few years, scientists hope to find more enzymes, discovered more possibilities.

only time will prove that the CRISPR-Cas9 system is not the best gene editing tools, or is it just a scientific revolution beginning. For different fields of application, the scientists also need a lot of research to determine what tool is most appropriate, currently can do, perhaps only at the same time advancing all of these system studies. You want to put gene editing technologies applied to human diseases treatment, crop cultivation and carrying disease insect control, may also need many years of time. (Any day.

Published at Tue, 30 Jan 2018 13:24:53 +0000

Leave a Reply