Identification of the mechanism underlying the genetic modes of species-specific phenotypic differences

虽然在人类和小鼠中由晶状体纤维主要内在蛋白(MIP)突变引起的白内障形成具有主要的遗传模式，但在MIP中插入5个碱基并截断该蛋白的大鼠模型KFRS4的白内障发生是隐性遗传的。为了证实人类/小鼠和大鼠在白内障发生的遗传模式上的物种特异性差异，我们产生了新的小鼠和大鼠MIP突变体，并分析了它们的晶状体表型。首先，我们通过使用CRISPR/Cas9进行基因组编辑，创建了具有与KFRS4大鼠相似的突变的小鼠突变。杂合子MIP突变体表现出严重的晶状体混浊。接下来，我们筛选了一个ENU突变文库，寻找新的大鼠MIP突变，并确定了两个错义突变，它们位于与人类患者的已知突变位点类似的位置。在晶状体的表型分析中，在任何一种MIP突变杂合的大鼠中没有观察到晶状体混浊。

Although cataract formation caused by major intrinsic protein of lens fiber (Mip) mutations in humans and mice has a dominant mode of inheritance, cataractogenesis in a rat model KFRS4, which has a 5-bp insertion in Mip that truncates the protein, is recessively inherited. To confirm the species-specific differences in the genetic mode of cataractogenesis between humans/mice and rats, we generated new mouse and rat Mip mutants and analyzed their lens phenotypes. First, we created mouse mutants with mutations similar to that in the KFRS4 rat by performing genome editing using CRISPR/Cas9. The heterozygous Mip mutants exhibited severe lens opacity. Next, we screened an ENU mutagenesis library for novel rat Mip mutations and identified two missense mutations located at sites analogous to known mutation sites in human patients. In phenotypic analyses of the lenses, no lens opacity was observed in the rats heterozygous for either Mip mutation.