AsianScientist (Jul. 15, 2015) – Using gene editing technology, researchers have overcome imprinting errors to improve the birth rate from fertilization with sperm replacement cells ten times. Their findings have been published in Cell Stem Cell.
In 2012, a research group led by Professors Li Jinsong and Xu Guoliang published a Cell paper reporting the creation of androgenetic haploid embryonic stem cells (AG-haESCs). These sperm replacement cells could support full-term embryonic development upon injection into oocytes, leading to the generation of semi-cloned (SC) mice.
Unfortunately, one major drawback was that AG-haESC-derived embryos had aberrant development and a very low birth rate of healthy SC mice (around two percent of total SC embryos), restricting their potential applications.
In the present study, a team of researchers from Shanghai Institutes for Biological Sciences led by Professors Li Jinsong, Wu Yuxuan of the Institute of Biochemistry and Cell Biology, and Yang Li of CAS-MPG Partner Institute for Computational Biology, improved the generation of SC pups to 20 percent.
Using CRISPR-Cas9 gene-editing technology, they showed that AG-haESCs carrying deletions in the differentially DNA methylated regions controlling two paternally repressed imprinted genes, H19 and Gtl2, led to a higher rate successful SC pup birth. Moreover, they demonstrated that manipulation of multiple genes is feasible, leading to the generation of SC mice carrying multiple genetic traits at an appropriate efficiency.
Importantly, they further showed that by combining the modified sperm replacement cells with a CRISPR-Cas9 library, SC mice carrying different mutant genes can be efficiently generated in one step. This enables functional mutagenic screening at organism level in mice, a technique which previously could only be done in lower organisms, such as yeast and C. elegans.
The researchers proposed that this new technology is feasible for medium-scale targeted screening at organism level, especially for developmental phenotypes, using the appropriate sgRNA libraries targeting pre-selected candidate genes.
The article can be found at: Zhong et al. (2015) CRISPR-Cas9-Mediated Genetic Screening in Mice with Haploid Embryonic Stem Cells Carrying a Guide RNA Library.
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Source: Chinese Academy of Sciences; Photo: Shutterstock.
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