360 DOUBLE KNOCKOUT OF GOAT MYOSTATIN AND PRION PROTEIN GENE USING CLUSTERED REGULARLY INTERSPACED SHORT PALINDROMIC REPEAT (CRISPR)/Cas9 SYSTEMS

Abstract

Myostatin (MSTN) acts as a negative regulator of skeletal muscle development and growth. Inhibition of MSTN expression may be applied to enhance animal growth performance in livestock production. Prion protein (PrPc) is associated directly with the pathogenesis of the transmissible spongiform encephalopathies occurring in variety of species including human, cattle, sheep, goats and deer. Prion protein-deficient livestock may be a useful model for prion research and producing animal conferring potential disease resistance. The goal of this study was to generate MSTN/PrPc double knockout goat by using CRISPR (clustered regularly interspaced short palindromic repeats)/Cas9 system. We generated 2 CRISPR/Cas9 plasmids targeting MSTN and PrPc genes, respectively. The CRISPR/Cas9 plasmids targeting each gene were respectively transfected into goat fibroblasts, and the efficiency of gene modification was determined at Day 3 using restriction fragment length polymorphism (RFLP) assay. The RFLP assay showed that CRISPR/Cas9 plasmids targeting MSTN and PrPc induced precise gene mutations with efficiency of 59 and 70%, respectively. Single cell-derived colonies were further isolated by limiting dilution after co-transfection of 2 CRISPR/Cas9 plasmids targeting MSTN and PrPc. The RFLP assay and DNA sequence analysis indicated that 9 out of 45 colonies (20%) carried simultaneous disruption of both target genes. Moreover, 5 of 9 mutant colonies (55%) had mutations in all 4 alleles of 2 genes. These double-gene knockout fibroblast cells will be used as nuclear donors for developing double knockout goat deficient in MSTN and PrPc. The CRISPR/Cas9 system represents a highly effective and facile platform for multiplex editing of large animal genomes, which can be broadly applied to both biomedical and agricultural applications.This work was supported by the Utah Science Technology and Research Initiative and Utah Agricultural Experiment Station project #31294.