Programmable base editing of the sheep genome revealed no genome-wide off-target mutations

Academic Article

Abstract

  • Copyright © 2019 Zhou, Cai, He, Wang, Ding, Liu, Liu, Ding, Zhao, Li, Li, Yu, Kou, Niu, Petersen, Sonstegard, Ma, Chen and Wang. Since its emergence, CRISPR/Cas9-mediated base editors (BEs) with cytosine deaminase activity have been used to precisely and efficiently introduce single-base mutations in genomes, including those of human cells, mice, and crop species. Most production traits in livestock are induced by point mutations, and genome editing using BEs without homology-directed repair of double-strand breaks can directly alter single nucleotides. The p.96R > C variant of Suppressor cytokine signaling 2 (SOCS2) has profound effects on body weight, body size, and milk production in sheep. In the present study, we successfully obtained lambs with defined point mutations resulting in a p.96R > C substitution in SOCS2 by the co-injection of BE3 mRNA and a single guide RNA (sgRNA) into sheep zygotes. The observed efficiency of the single nucleotide exchange in newborn animals was as high as 25%. Observations of body size and body weight in the edited group showed that gene modification contributes to enhanced growth traits in sheep. Moreover, targeted deep sequencing and unbiased family trio-based whole genome sequencing revealed undetectable off-target mutations in the edited animals. This study demonstrates the potential for the application of BE-mediated point mutations in large animals for the improvement of production traits in livestock species.
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    Digital Object Identifier (doi)

    Author List

  • Zhou S; Cai B; He C; Wang Y; Ding Q; Liu J; Liu Y; Ding Y; Zhao X; Li G
  • Volume

  • 10
  • Issue

  • MAR