Different expression patterns of Lin28 and Lin28b in mouse molar development

•Lin28 and Lin28b have different expression patterns during molar tooth development.•Lin28 is expressed in mouse molar tooth germs in all developmental stages.•Lin28b is predominately expressed in enamel organ before bell stage.•Lin28 may play a role in dental epithelial proliferation and epithelial-ectomesenchymal interaction.•Lin28 is persistently located in ameloblasts and odontoblasts since late bell stage.

ObjectiveThe RNA-binding proteins Lin28 and Lin28b are expressed in many developing tissues and are involved in the biosynthesis of the microRNA let-7 family and embryogenesis processes. However, their roles in mammalian tooth development remain ill-defined.DesignThe spatiotemporal expressions of Lin28 and Lin28b during mouse molar odontogenesis from day E11.5 to P21 were examined through immunohistochemistry and western blot analysis.ResultsBoth Lin28 and Lin28b were initially expressed in dental epithelium, but the expression patterns varied thereafter. Lin28 was expressed in tooth germ from early embryonic stages and was consistently expressed in the ameloblasts and odontoblasts throughout all stages of tooth development. However, positive staining of Lin28b gradually faded out with tooth germ development, before finally disappearing in tooth organ cells after birth.ConclusionsThese results indicate that Lin28 was spatiotemporally expressed in tooth germ throughout tooth development progression and may play an active role in ameloblast and odontoblast differentiation, as well as matrix secretion and the mineralization of enamel and dentin. Its paralogue Lin28b may have a distinct function in tooth germ formation.