Enamel Mineral Composition of Normal and Cystic Fibrosis Transgenic Mice

Abstract

The ability of ameloblasts and the enamel organ to control the influx of ions into the developing enamel is of considerable interest. The development of transgenic mice lacking a cAMP-regulated chloride channel, the cystic fibrosis transmembrane conductance regulator (CFTR), provides a model that may prove valuable for the study of ion regulation in developing teeth. The purpose of this investigation was to characterize the mineral content of normal and CF mice. Five homozygous and five heterozygous adult mice having the CFTR knockout transgene were evaluated. The mice were killed with CO2 and their mandibular incisors removed, embedded in methacrylate, and sectioned, and enamel particles from the incisal region were then dissected for analysis. Each particle was analyzed for its calcium, phosphorus, and magnesium content. The normal mice had a mean mineral content of 80.5%, in contrast to the CF mice, that had markedly hypomineralized enamel (mean = 51.5%). The calcium/phosphorus ratios were similar for both groups of mice and were compatible with the enamel consisting primarily of hydroxyapatite mineral. The enamel magnesium content was significantly elevated in the CF mice (mean = 3560 ppm) compared with the normal mice (mean = 2280 ppm). Normal mouse enamel was highly mineralized, while the CF mouse enamel mineral content was significantly reduced and had an elevated level of magnesium. The altered mineral content of CF mouse enamel indicates that CFTR could play an important role in ion regulation and consequently mineralization of mouse enamel.

Systemic disorders and their influence on the development of dental hard tissues: A literature review

“…6 Further molecular studies using the transgenic CF mouse have clearly shown that the CFTR gene is expressed in developing teeth and other mineralised tissues and is associated with abnormal development of incisors. [19][20][21][22][23] Wright et al 22,23 showed that all CF mice had soft, chalky white incisor enamel compared to hard, yellow-brown in normal mice. They exhibited premature degeneration of ameloblasts with increased retention of enamel matrix proteins and a decreased mineralisation of the enamel.…”

NBCe1 (SLC4A4) a potential pH regulator in enamel organ cells during enamel development in the mouse

“…For this we used two other mouse models in which pH regulation is disrupted which severely affects enamel formation: the AE2a,b −/− (Lyaruu et al 2008) and CFTR −/− mice (Wright et al 1996; Bronckers et al 2010)…”

Transgenic Cystic Fibrosis Mice Exhibit Reduced Early Clearance of Pseudomonas aeruginosa from the Respiratory Tract

“…The two ⌬F508 Cftr-transgenic CF mouse strains were maintained using breeding pairs of heterozygous Cftr female mice and ⌬F508 Cftr homozygous male mice. Mouse genotype for the ⌬F508 Cftr mice was checked by PCR of DNA isolated from tails using published protocols for each strain (10,11) and by phenotypic examination of tooth color, as described previously (13). Drinking water was treated with 200 g gentamicin/ml to prevent growth of P. aeruginosa.…”