Scientists at MIT and Broad Institute have successfully surmounted a significant impediment in CRISPR-Cas9 gene editing technology.
In a groundbreaking development, researchers at the Broad Institute of MIT and Harvard, in collaboration with the McGovern Institute for Brain Research at MIT, have engineered modifications to the CRISPR-Cas9 genome editing system that substantially decrease "off-target" editing errors. This refined technique addresses one of the critical technical issues encountered in genome editing, as reported in a paper published today in Science.
The CRISPR-Cas9 system is transformative, allowing for precise modifications in a cell's DNA. The Cas9 protein alters the DNA at a specified location, determined by a short RNA whose sequence matches that of the target site. Though Cas9 is renowned for its high efficiency in cutting its target site, an issue with the system has been its tendency to bind and cut additional sites that are not targeted, potentially leading to undesired edits that could result in the development of cancer or other complications.
In the new study, Feng Zhang and his colleagues have found that altering three of the 1,400 amino acids that make up the Cas9 enzyme significantly reduced "off-target editing" to virtually undetectable levels in specific cases examined. Zhang, the W.M. Keck Career Development Professor in Biomedical Engineering at MIT, hopes this advancement will help address some of the safety concerns related to off-target effects, even as the field continues to advance rapidly.
The researchers used their knowledge about the structure of the Cas9 protein to decrease off-target cutting. They replaced some positively charged amino acids with neutral ones, predicting that this change would diminish the binding of "off-target" sequences much more than "on-target" sequences. The resultant modified enzyme, now known as "enhanced" S. pyogenes Cas9, or eSpCas9, will be made available for global researchers immediately.
The same charge-changing approach is likely to work with other recently described RNA-guided DNA targeting enzymes, including Cpf1, C2C1, and C2C3. The Zhang Lab's findings open up new possibilities for genome editing applications requiring high precision.
However, while this advancement represents a significant milestone, Zhang acknowledges that it does not constitute a "magic bullet." He emphasizes that the field is evolving quickly, and further learning is necessary before considering applying this technology for clinical use. Zhang is set to speak on the ethical and societal implications of the developing gene editing field today at the International Summit on Gene Editing in Washington.
Several advancements have recently been focusing on improving the precision and reducing unintended changes in gene editing. Other methods, such as base editing and prime editing, avoid the creation of double-strand breaks, known contributors to off-target effects. Additionally, bioinformatics tools are used for pre-screening genetic targets to predict and avoid off-target sites, further enhancing the specificity of CRISPR-Cas9.
As the promise of rapid and efficient genome editing raises ethical and societal concerns, the development of eSpCas9 could help address some of those concerns, potentially paving the way for future therapeutic applications.
- The refined CRISPR-Cas9 genome editing system, engineered by researchers in collaboration with MIT and Harvard, was reported in a paper published today in Science.
- The new study, led by Feng Zhang, has significantly decreased "off-target" editing errors, a critical technical issue in genome editing.
- The modified enzyme, known as "enhanced" S. pyogenes Cas9, or eSpCas9, is expected to help address safety concerns related to off-target effects.
- Zhang's lab has found that the same charge-changing approach is likely to work with other RNA-guided DNA targeting enzymes, including Cpf1, C2C1, and C2C3.
- As the field of genome editing continues to evolve, bioinformatics tools are used for pre-screening genetic targets to predict and avoid off-target sites.
- Zhang will be speaking on the ethical and societal implications of the developing gene editing field today at the International Summit on Gene Editing in Washington, addressing concerns related to health-and-wellness, therapies-and-treatments, and technology.
