Gene editing and its applications in biomedicine

The steady progress in genome editing, especially genome editing based on the use of clustered regularly interspaced short palindromic repeats(CRISPR) and programmable nucleases to make precise modifications to genetic material, has provided enormous opportunities to advance biomedical research and promote human health. The application of these technologies in basic biomedical research has yielded significant advances in identifying and studying key molecular targets relevant to human diseases and their treatment. The clinical translation of genome editing techniques offers unprecedented biomedical engineering capabilities in the diagnosis, prevention, and treatment of disease or disability. Here, we provide a general summary of emerging biomedical applications of genome editing, including open challenges. We also summarize the tools of genome editing and the insights derived from their applications, hoping to accelerate new discoveries and therapies in biomedicine.

Computer-aided engineering of CRISPR-Cas proteins for enhanced human genome editing

Dear editor.The remarkably diversified CRISPR-Cas systems in nature have provided unlimited valuable resources to develop genome editing tools that are revolutionizing the fields of biotechnology and medicine.However,due to their microbial origin,the activity of most naturally occurring CRISPR-Cas nucleases is relatively poor in mammalian cells(Ran et al.,2015).Thus,improving the mammalian genome editing efficiency becomes the priority for harnessing more CRISPRCas systems for widespread applications.Rational protein engineering serves as a powerful approach to enhance the catalytic activity of enzymes.Whereas,this approach largely relies on proteinic three-dimension(3D)structure information as guide for design.The fact is that of the large numbers of the CRISPR-Cas systems discovered in recent years,only a small number of them with the 3D structures were reported.To bypass this limitation,here,we report an efficient and simple strategy for rational engineering of Cas nucleases without the need of 3D structure information and successfully optimized nucleases from Cas9 and Cas12 families.

Synergistic engineering of CRISPR-Cas nucleases enables robust mammalian genome editing

The naturally occurring prokaryotic CRISPR-Cas systems provide valuable resources for the development of new genome-editing tools.However,the majority of prokaryotic Cas nucleases exhibit poor editing efficiency in mammalian cells,which significantly limits their utility.Here,we have developed a method termed Improving Editing Activity by Synergistic Engineering(MIDAS).This method exerts a synergistic effect to improve mammalian genome-editing efficiency of a wide range of CRISPR-Cas systems by enhancing the interactions of Cas nuclease with the protospacer adjacent motif(PAM)and the single-stranded DNA(ssDNA)substrate in the catalytic pocket simultaneously.MIDAS robustly and significantly increased the gene-editing efficiency of Cas12i,Cas12b,and CasX in human cells.Notably,a Cas12i variant,Cas12iMax,exhibited robust activity with a very broad PAM range(NTNN,NNTN,NAAN,and NCAN)and higher efficiency than the current widely used Cas nucleases.A high-fidelity version of Cas12iMax(Cas12iHiFi)has been further engineered to minimize off-target effects.Our work provides an expandable and efficacious method for engineering Cas nucleases for robust mammalian genome editing.