A Suite of Mouse Reagents for Studying Amelogenesis

Abstract

Amelogenesis, the formation of dental enamel, is driven by specialized epithelial cells called ameloblasts, which undergo successive stages of differentiation. Ameloblasts secrete enamel matrix proteins (EMPs), proteases, calcium, and phosphate ions in a stage-specific manner to form mature tooth enamel. Developmental defects in tooth enamel are common in humans, and they can greatly impact the well-being of affected individuals. Our understanding of amelogenesis and developmental pathologies is rooted in past studies using epithelial Cre driver and knockout alleles. However, the available mouse models are limited, as most do not allow targeting different ameloblast subpopulations, and constitutive loss of EMPs often results in severe phenotype in the mineral, making it difficult to interpret defect mechanisms. Herein, we report on the de-sign and verification of a toolkit of twelve mouse alleles that include ameloblast-stage specific Cre recombinases, fluorescent reporter alleles, and conditional flox alleles for the major EMPs. We show how these models may be used for applications such as sorting of live stage specific ameloblasts, whole mount imaging, and experiments with incisor explants.

Mobility gene expression differences among wild-type, Mmp20 null and Mmp20 over-expresser mice plus visualization of 3D mouse ameloblast directional movement

“…In this study we have generated reporter mice that use an Amelx -promoter driven tdTomato transgene to label mouse ameloblasts. There are previous reports that created reporter mice to label ameloblasts 21 – 23 . The first generated Enamelin-tdTomato transgenic reporter mice 22 .…”

“…Note that both Enamelin-tdTomato and our Amelx-tdTomato constructs were expressed in P5 1st molar secretory stage ameloblasts. The third study generated multiple reporter mice with ameloblast-stage specific Cre recombinases 23 . We generated two different Amelx-tdTomato transgenic mouse lines with two different tdTomato expression levels (Table 1 ) and each of our transgenic mice were useful depending on the experimental protocol.…”