Sun Guanjie, Liang Xinyu, Qin Ke, Qin Yufeng, Shi Xuan, Cong Peiqing, Mo Delin, Liu Xiaohong, Chen Yaosheng, He Zuyong
State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-Sen University, Guangzhou, China.
Front Genet. 2020 Mar 3;11:138. doi: 10.3389/fgene.2020.00138. eCollection 2020.
The dominant white phenotype in pigs is thought to be mainly due to a structural mutation in the gene, a splice mutation (G > A) at the first base in intron 17 which leads to the deletion of exon 17 in the mature mRNA. However, this hypothesis has not yet been validated by functional studies. Here, we created two mouse models, to mimic the splice mutation, and to partially mimic the duplication mutation of gene in dominant white pigs using CRISPR/Cas9 technology. We found that the splice mutation homozygote is lethal and the heterozygous mice have a piebald coat. Slightly increased expression of KIT in mice did not confer the patched phenotype and had no obvious impact on coat color. Interestingly, the combination of these two mutations reduced the phosphorylation of PI3K and MAPK pathway associated proteins, which may be related to the impaired migration of melanoblasts observed during embryonic development that eventually leads to the dominant white phenotype.
猪的显性白色表型被认为主要是由于该基因的结构突变，即内含子17第一个碱基处的剪接突变（G>A），这导致成熟mRNA中外显子17的缺失。然而，这一假设尚未得到功能研究的验证。在此，我们利用CRISPR/Cas9技术创建了两种小鼠模型，一种模拟剪接突变，另一种部分模拟显性白色猪中该基因的重复突变。我们发现剪接突变纯合子是致死的，杂合小鼠有花斑毛色。KIT在小鼠中的表达略有增加并未赋予斑驳表型，对毛色也没有明显影响。有趣的是，这两种突变的组合降低了PI3K和MAPK信号通路相关蛋白的磷酸化水平，这可能与胚胎发育过程中观察到的黑素母细胞迁移受损有关，最终导致显性白色表型。
