IADR Abstract Archives
Revealing The Roles Of Circadian Clock Genes In Amelogenesis
Objectives: Circadian rhythms are maintained via the differential expression of several clock genes including Per2 and Bmal1. We previously demonstrated that both genes are robustly expressed by the differentiating ameloblasts and their expression and localization alternate in a circadian manner in vitro. We aimed to evaluate the multi-level control exerted by these clock genes on amelogenesis in vivo and to examine the effects of circadian disruption on enamel secretion and maturation.
Methods: We examined the enamel phenotype in Per2 and Bmal1 clock gene knock-out (KO) mouse models using gross morphology, SEM-EDX imaging, and micro-CT analysis. Changes in gene expression levels of key circadian and ameloblast genes were evaluated by immunohistochemistry, qRT-PCR, microarray and RNAseq analyses to elucidate the links between the circadian molecular dysregulation and enamel phenotype in the both KO mice.
Results: Per2-KO resulted in a severely defective enamel phenotype with significant changes in enamel structure and mineralization. Dentin and alveolar bone and density was also significantly lower Per2-KO mice compared to wild type. Bmal1-KO did not result in abnormal enamel formation and no significant changes in bone and dentin were observed. Per2 deletion had resulted in very significant changes in the expression of the other components of the circadian pathways while Bmal1 deletion led to a much lower degree of circadian dysregulation which may explain the phenotypic differences. Per2 appears also to modulate calcium transport during enamel mineralization through regulating the expression of the Orai/Stim calcium channels axis.
Conclusions: The time-related control of amelogenesis is mediated via the circadian regulation of multiple key ameloblast genes. More studies are needed to fully comprehend the interplay between circadian and developmental controls of amelogenesis. Understanding the circadian controls of amelogenesis will provide the basis for understanding phenotypic variabilities in enamel development and diseases among populations.
Methods: We examined the enamel phenotype in Per2 and Bmal1 clock gene knock-out (KO) mouse models using gross morphology, SEM-EDX imaging, and micro-CT analysis. Changes in gene expression levels of key circadian and ameloblast genes were evaluated by immunohistochemistry, qRT-PCR, microarray and RNAseq analyses to elucidate the links between the circadian molecular dysregulation and enamel phenotype in the both KO mice.
Results: Per2-KO resulted in a severely defective enamel phenotype with significant changes in enamel structure and mineralization. Dentin and alveolar bone and density was also significantly lower Per2-KO mice compared to wild type. Bmal1-KO did not result in abnormal enamel formation and no significant changes in bone and dentin were observed. Per2 deletion had resulted in very significant changes in the expression of the other components of the circadian pathways while Bmal1 deletion led to a much lower degree of circadian dysregulation which may explain the phenotypic differences. Per2 appears also to modulate calcium transport during enamel mineralization through regulating the expression of the Orai/Stim calcium channels axis.
Conclusions: The time-related control of amelogenesis is mediated via the circadian regulation of multiple key ameloblast genes. More studies are needed to fully comprehend the interplay between circadian and developmental controls of amelogenesis. Understanding the circadian controls of amelogenesis will provide the basis for understanding phenotypic variabilities in enamel development and diseases among populations.
