Characterization of Defects in Ion Transport and Tissue Development in Cystic Fibrosis Transmembrane Conductance Regulator (CFTR)-Knockout Rats

Abstract

Animal models for cystic fibrosis (CF) have contributed significantly to our understanding of disease pathogenesis. Here we describe development and characterization of the first cystic fibrosis rat, in which the cystic fibrosis transmembrane conductance regulator gene (CFTR) was knocked out using a pair of zinc finger endonucleases (ZFN). The disrupted Cftr gene carries a 16 base pair deletion in exon 3, resulting in loss of CFTR protein expression. Breeding of heterozygous (CFTR+/−) rats resulted in Mendelian distribution of wild-type, heterozygous, and homozygous (CFTR−/−) pups. Nasal potential difference and transepithelial short circuit current measurements established a robust CF bioelectric phenotype, similar in many respects to that seen in CF patients. Young CFTR−/− rats exhibited histological abnormalities in the ileum and increased intracellular mucus in the proximal nasal septa. By six weeks of age, CFTR−/− males lacked the vas deferens bilaterally. Airway surface liquid and periciliary liquid depth were reduced, and submucosal gland size was abnormal in CFTR−/− animals. Use of ZFN based gene disruption successfully generated a CF animal model that recapitulates many aspects of human disease, and may be useful for modeling other CF genotypes, including CFTR processing defects, premature truncation alleles, and channel gating abnormalities.

Oral cavity health among cystic fibrosis patients: Literature overview

“…Premature degeneration of ameloblasts resulting in altered firmness and coloration of the enamel has been observed in mice with CF. 29 The aforementioned data is confirmed in certain clinical reports. 23,31,32 Ferrezzano et al have observed developmental enamel defects in 56% of the subjects with CF; the same concerned 22% of the healthy subjects.…”

“…18 Research conducted on laboratory animals has shown a connection between disturbances in ion balance related to the defect of the CFTR protein and the occurrence of disturbed enamel mineralization. [27][28][29][30] Tuggle et al have observed a change in the coloration and lack of physiological abrasion of incisors in rats devoid of the CFTR gene. Premature degeneration of ameloblasts resulting in altered firmness and coloration of the enamel has been observed in mice with CF.…”

Development of an airway mucus defect in the cystic fibrosis rat

“…Preliminary characterization demonstrated completely absent CFTR expression and function in all tissues, including the airways, combined with initial events that characterize the CF lung, namely a dehydrated airway surface (26). Additionally, the rat expresses a higher number of submucosal glands in the upper airways, especially tracheae and bronchi (27), a feature that has been shown to be important to human CF disease (28)(29)(30)(31)(32)(33).…”

In vivo imaging of airway cilia and mucus clearance with micro-optical coherence tomography

“…More recently, we have utilized µOCT for in vitro imaging of the airway surface, including the cilia [10][11][12][13][14]. Cilia are microscopic organelles that line respiratory epithelia and beat repeatedly in a sweeping motion to clear mucus from the airways.…”