Illuminating the path to DNA repair.

Diverse DNA repair pathways correct ranging types of damage and play central roles in genome editing. In this issue of Cell, two publications leverage a new high-throughput screen that links pathway genes with the outcomes of repair, yielding mechanistic insights into the repair process as well as means to shape editing outcomes.

Modification of Cas9, gRNA and PAM: Key to further regulate genome editing and its applications.

The discovery of CRISPR-Cas9 system has revolutionized the genome engineering research and has been established as a gold standard genome editing platform. This system has found its application in biochemical researches as well as in medical fields including disease diagnosis, development of therapeutics, etc. The enormous versatility of the CRISPR-Cas9 as a high throughput genome engineering platform, is derailed by its off-target activity. To overcome this, researchers from all over the globe have explored the system structurally and functionally and postulated several strategies to upgrade the system components including redesigning of Cas9 Nuclease and modification of guide RNA(gRNA) structure and customization of the protospacer adjacent motif. Here in this review, we portray the comprehensive overview of the strategies that has been adopted for redesigning the CRISPR-Cas9 system to enhance the efficiency and fidelity of the technology.

CRISPR-Cas9 system: A new-fangled dawn in gene editing.

Till date, only three techniques namely Zinc Finger Nuclease (ZFN), Transcription-Activator Like Effector Nucleases (TALEN) and Clustered Regularly Interspaced Short Palindromic Repeats-CRISPR-Associated 9 (CRISPR-Cas9) are available for targeted genome editing. CRISPR-Cas system is very efficient, fast, easy and cheap technique for achieving knock-out gene in the cell. CRISPR-Cas9 system refurbishes the targeted genome editing approach into a more expedient and competent way, thus facilitating proficient genome editing through embattled double-strand breaks in approximately any organism and cell type. The off-target effects of CRISPR Cas system has been circumnavigated by using paired nickases. Moreover, CRISPR-Cas9 has been used effectively for numerous purposes, like knock-out of a gene, regulation of endogenous gene expression, live-cell labelling of chromosomal loci, edition of single-stranded RNA and high-throughput gene screening. The execution of the CRISPR-Cas9 system has amplified the number of accessible scientific substitutes for studying gene function, thus enabling generation of CRISPR-based disease models. Even though many mechanistic questions are left behind to be answered and the system is not yet fool-proof i.e., a number of challenges are yet to be addressed, the employment of CRISPR-Cas9-based genome engineering technologies will increase our understanding to disease processes and their treatment in the near future. In this review we have discussed the history of CRISPR-Cas9, its mechanism for genome editing and its application in animal, plant and protozoan parasites. Additionally, the pros and cons of CRISPR-Cas9 and its potential in therapeutic application have also been detailed here.