Development of Mouse Models for Cystic Fibrosis

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Cystic fibrosis (CF) is a common, lethal, autosomal recessive disorder caused by mutations in the CFTR gene, with the most common mutation (ΔF508) occurring on ∼70% of CF chromosomes. Dysfunction of the CFTR protein, which acts as an apically localized epithelial chloride ion channel, results in the classical manifestations of CF: salty sweat, pancreatic insufficiency, intestinal obstruction, male infertility, and severe pulmonary disease, with characteristic abnormalities in electrolyte transport. The most serious consequence is progressive and ultimately fatal inflammatory lung disease characterized by chronic microbial colonization and repeated acute exacerbations of pulmonary infection, with a distinctive spectrum of pathogens. These clinical manifestations show considerable variation between individuals because of an as yet incompletely understood combination of environmental factors, independently segregating disease-modifying genes, and differences between specific CFTR mutations. The development of mouse models for cystic fibrosis has provided the opportunity to dissect disease pathogenesis, correlate genotype and phenotype, study disease-modifying genes and develop novel therapeutics.
This review discusses the successes and the challenges encountered in characterizing and optimizing these models. CF mouse models demonstrate wide evidence of intestinal disease, but they exhibit large variation in survival, anatomically confined CF ion transport defect, and general absence of CF-like lung disease. The breeding of Cftr-null mice onto different mouse genetic backgrounds can also alter disease severity, suggesting that other genetic loci may modify the severity of CFTR mutations ( Rozmahel et al., 1996).
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... different Hit clones, with a correct karyotype and heterozygous for the deltaf508 mutation, were injected into blastocysts and gave rise to sex conversion and colour chimerism. Two male chimeras showed full germline transmission in a cross with FVB mice as indicated by coat color and southern blot analysis.
To check the correct transcription of the deltaf508 allele, we isolated intestinal RNA from normal and mutant mice and performed a nested RT-PCR analysis with primers in exon 8 and 10. Since the deltaF508 allele contains the SspI site in exon10, we can distinguish the normal from the mutant pcr product. Mice heterozygous (delta F/N) or homozygous(F/F) for the delta F508 mutation produced the predicted 359bp fragment after SspI digestion of the PCR product. Sequence analysis of the PCR products showed that the mutant formof CFTR mRNA had the predicted sequence
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