This article has been updated with additional details of the project.
NEW YORK (GenomeWeb) – The Jackson Laboratory announced this week that it has been awarded a two-year, $455,000 grant from the National Institutes of Health to support an effort to improve the accuracy of CRISPR/Cas9 genome editing in mammalian embryos.
CRISPR involves the use of a specific enzyme, Cas9, to cause double-strand DNA breaks that induce gene silencing. Researchers are also able to induce specific genetic changes with DNA templates that are incorporated into these breaks, typically by a process called homology directed repair (HDR).
HDR in mammalian embryos, however, is imprecise and inefficient due to variables including a target cell's differentiated state, donor DNA, and targeting nuclease, according to the grant's abstract. Meanwhile, current optimization approaches using reporter constructs for HDR in preimplantation embryos do function are limited to active genes. For embryos that are developed to term, the testing of multiple HDR variables is resource intense, and using immortalized cell lines does not accurately reflect the zygote phenotype.
With the NIH funding, Jackson Lab researcher Michael Wiles and his colleagues aim to improve targeted nuclease-mediated HDR by developing and validating a high-throughput, low-cost approach for testing multiple variables involved in targeting HDR directly in mouse zygotes, and make their findings publicly available.
Specifically, they aim to use preimplantation mouse embryos to establish and validate a high-throughput sequencing-based analytical strategy that determines the targeted allele frequency and accuracy of targeted nuclease-mediated DNA repair events, including HDR, for three selected genomic regions. They will then use this platform to test the variables involved in targeted nuclease-mediated HDR, with a focus on DNA format.