LONG-TERM SURVIVAL OF THE EXON-10 INSERTIONAL CYSTIC-FIBROSIS MUTANT MOUSE IS A CONSEQUENCE OF LOW-LEVEL RESIDUAL WILD-TYPE CFTR GENE-EXPRESSION
LONG-TERM SURVIVAL OF THE EXON-10 INSERTIONAL CYSTIC-FIBROSIS MUTANT MOUSE IS A CONSEQUENCE OF LOW-LEVEL RESIDUAL WILD-TYPE CFTR GENE-EXPRESSION
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DOI：
10.1007/bf00369314
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发表时间：
1994-08-01
期刊：
影响因子：
2.5
通讯作者：
PORTEOUS, DJ
中科院分区：
文献类型：
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作者：
DORIN, JR;STEVENSON, BJ;PORTEOUS, DJ
最近，我们通过向外显子10插入基因靶向建立了囊性纤维化(CF)的小鼠模型。与囊性纤维化受试者一样，该模型显示胎粪性肠梗阻的发生率较低。这与迄今为止所描述的其他三种CF小鼠模型中非常高的致命性肠梗阻水平形成了鲜明的对比。我们在这里研究这种表型差异的分子基础。我们发现，插入基因打靶导致的部分复制允许外显子跳过和异常剪接产生正常的CFTRmRNA，但与野生型小鼠相比，水平大大降低。此外，不是预测的突变CFTR转录本，而是产生了一种新的利用干扰质粒序列中的隐蔽剪接位点的mRNA。然而，我们之前已经证明，这些小鼠表现出CF的离子转运缺陷特征，在此基础上，突变动物可以与它们的正常后代区分开来。与此一致的是，最近在表现出胰腺功能充足但仍有肺部疾病的CF患者中观察到了几个“轻微”突变的残留CFTR功能。我们得出的结论是：(I)外显子10插入突变小鼠中残留的野生型mRNA改善了绝对‘’空‘’CF小鼠观察到的肠道表型的严重程度；(Ii)低水平残留野生型CFTRmRNA的存在并不能纠正CF离子转运缺陷；(Iii)该插入突变小鼠的长期存活为解决肺部疾病发展中的重要因素提供了机会。
Recently we have created a mouse model of cystic fibrosis (CF) by insertional gene targeting to exon 10. In common with CF subjects, this model displays a low incidence of meconium ileus. This contrasts strikingly with the very high level of fatal intestinal obstruction in the three other CF mouse models so far described. We investigate here the molecular basis of this difference in phenotype. We show that the partial duplication consequent upon insertional gene targeting allows exon skipping and aberrant splicing to produce normal Cftr mRNA, but at levels greatly reduced compared with wild-type mice. Furthermore, instead of the predicted mutant Cftr transcript, a novel mRNA is produced that utilizes cryptic splice sites in the disrupting plasmid sequence. However, we have previously shown that these mice display the ion transport defect characteristic of CF, and mutant animals can be distinguished from their normal littermates on this basis. Consistent with this, residual CFTR function has recently been observed for several ''mild'' mutations in CF individuals who display pancreatic sufficiency but still develop lung disease. We conclude that (i) residual wild-type mRNA in the exon 10 insertional mutant mouse ameliorates the severity of the intestinal phenotype observed in the absolute ''null'' CF mice, (ii) the presence of low-level residual wild-type Cftr mRNA does not correct the CF ion transport defect, and (iii) the long-term survival of this insertional mutant mouse provides the opportunity to address the factors important in development of lung disease.