Molecular consequences of Dlx3 deletion in mouse enamel organ as determined by microarray analysis
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ABSTRACT: DLX3 is a homeodomain transcription factor involved in ameloblast differentiation and enamel formation. Mutations in DLX3 in human lead to defects in enamel. However, the downstream targets of Dlx3 transcriptional activity in the enamel organ have not been identified yet. In this study, we compared the transcriptome of enamel organs where Dlx3 has been deleted to control tissues.
Project description:DLX3 is a homeodomain transcription factor involved in ameloblast differentiation and enamel formation. Mutations in DLX3 in human lead to defects in enamel. However, the downstream targets of Dlx3 transcriptional activity in the enamel organ have not been identified yet. In this study, we compared the transcriptome of enamel organs where Dlx3 has been deleted to control tissues. Total RNA was extracted from enamel organs (mandibular incisors) from Dlx3-WT (N=4) and Dlx3-K14cKO (N=4) mice at P10. cDNA libraries were generated using NEBnext and NuGen kits. Sequencing was performed on the HiSeq2000.
Project description:DLX3 is a homeodomain transcription factor involved in ameloblast differentiation and enamel formation. Mutations in DLX3 in human lead to defects in enamel. However, the downstream targets of Dlx3 transcriptional activity in the enamel organ have not been identified yet. In this study, we compared the transcriptome of enamel organs where Dlx3 has been deleted to control tissues.
Project description:DLX3 is a homeodomain transcription factor involved in amelogenesis. Mutations in DLX3 in human lead to Tricho-Dento-Osseous syndrome featuring enamel hypoplasia and hypomineralization. Here we investigated the distribution of DLX3 DNA binding sites in rat enamel organ using ChIP-seq.
Project description:DLX3 is a homeodomain transcription factor involved in epidermal and hair follicle differentiation. Epidermal specific deletion of DLX3 leads to IL17 related inflammation. However, the downstream signals from DLX3-deficient keratinocytes that initiates IL17 associated inflammation is not well-characterized. Therefore we performed acute Dlx3 deletion to identify the initial molecular changes causing the skin inflammatory reponse and tried to rescue the immune phenotype by STAT3 inhibitor treatment (Cryptotanshinone). In this study, we compared the epidermal and dermal transcriptome from Dlx3 wild-type (WT) and K14CreERT;DLX3 fl/fl (icKO).
Project description:In a systemic effort to survive environmental stress, organ systems fluctuate and adapt to overcome external pressures. The evolutionary drive back towards homeostasis, makes it difficult to determine if an organism experienced a toxic exposure to stress, especially in early prenatal and neonatal periods of development. Previous studies indicate that primary human teeth may provide historical records of experiences related to stressors during that early time window. To assess the molecular effects of early life adversity on enamel formation, we used a limited bedding and nesting (LBN) mouse model of early life adversity (ELA), to assess changes in enamel organ gene expression and enamel mineralization. Enamel of postnatal day 12 (P12) weight-matched ELA mice was more mineralized as compared control enamel. RNAseq showed 724 genes significantly upregulated in ELA enamel organs as compared to controls, and 574 significantly downregulated genes (DESeq2 p-value <= 0.05). Transcripts expressing the enamel matrix proteins amelogenin (Amelx) and enamelin (Enam) were among the top 4 most differentially expressed genes. The most significantly enriched GO and Reactome pathway was Extracellular Matrix Organization, while the most significantly enriched KEGG Pathways were Butanoate metabolism and Synthesis and Degradation of Ketone Bodies. qPCR analysis of weight-matched ELA and control enamel organs confirmed that expression of the ameloblast-specific proteins Amelx and Enam were highly upregulated in ELA mice. When evaluating molecular mechanisms for amelogenin upregulation, we found significantly increased expression of Dlx3, while transcripts for clock genes Per1 and Nrd1, which have also positively associated with amelogenin expression, were downregulated. These findings suggest that the developing enamel organs are sensitive to the pressures of early life adversity and produce structural biomarkers in tooth enamel mineral to reflect these changes. Together these results support the possibility that tooth enamel may contain biomarkers of cellular effects associated with systemic early life adversity.
Project description:DLX3 is a homeodomain transcription factor involved in epidermal differentiation. Here we investigated the distribution of DLX3 DNA binding sites in suprabasal differentiating keratinocytes using ChIP-seq.
Project description:Coordinated mineralization of soft tissue is central to organismal form and function, while dysregulated mineralization underlies several human pathologies. Oral epithelial derived ameloblasts are polarized, secretory cells responsible for generating enamel, the most mineralized substance in the human body. Defects in ameloblast development result in enamel anomalies, including amelogenesis imperfecta. Identifying proteins critical in ameloblast development can provide insight into specific pathologies associated with enamel related disorders or more broadly, mechanisms of mineralization. Previous studies identified a role for MEMO1 in bone mineralization; however, whether MEMO1 functions in the generation of additional mineralized structures remains unknown. Here, we identify a critical role for MEMO1 in enamel mineralization. First, we identified that Memo1 is expressed in ameloblasts and that conditional deletion of Memo1 from ameloblasts results in enamel defects, characterized by a decline in mineral density and tooth integrity. Molecular profiling of ameloblasts and their progenitors in Memo1 oral epithelial mutants revealed a disruption to cytoskeletal associated genes and a reduction in late stage ameloblast markers, relative to controls. Histology revealed that the molecular defects correlated with a disruption of the apical Tome’s process and the basolateral interacting, papillary layer, in Memo1 mutant ameloblasts. Finally, deletion of Memo1 from an oral epithelial ameloblast cell line, followed by cellular and molecular analyses, revealed altered cytoskeletal networks, relative to control cells. Collectively, our findings integrate MEMO1 into an emerging network of molecules important for ameloblast development and provide both in vivo and in vitro systems to further interrogate the relationship of cytoskeletal and amelogenesis-related defects.
Project description:Dental enamel, the hardest tissue in the human body, is derived from dental epithelial cell ameloblast-secreted enamel matrices. Enamel mineralization occurs in a strictly synchronized manner along with ameloblast maturation in association with ion transport and pH balance, and any disruption of these processes results in enamel hypomineralization. G-protein coupled receptors (GPCRs) function as transducers of external signals by activating associated G-proteins and regulate cellular physiology. Tissue-specific GPCRs play important roles in organ development, though their activities in tooth development remains poorly understood. The present results show that the adhesion-GPCR Gpr115 (Adgrf4) is highly and preferentially expressed in mature ameloblasts and plays a crucial role during enamel mineralization. To investigate the in vivo function of Gpr115, knockout (Gpr115-KO) mice were created and found to develop hypo-mineralized enamel, with a larger acidic area due to the dysregulation of ion composition. Transcriptomic analysis also revealed that deletion of Gpr115 disrupted pH homeostasis and ion transport processes in enamel formation. In addition, in vitro analyses using the dental epithelial cell line Cervical Loop-Derived Dental Epithelial (CLDE) cell demonstrated that Gpr115 is indispensable for the expression of carbonic anhydrase 6 (Car6), which has a critical role in enamel mineralization. Furthermore, an acidic condition induced Car6 expression under the regulation of Gpr115 in CLDE cells. Thus, we concluded that Gpr115 plays an important role in enamel mineralization via regulation of Car6 expression in ameloblasts. The present findings indicate a novel function of Gpr115 in ectodermal organ development and clarify the molecular mechanism of enamel formation.
Project description:Tooth enamel secreted by ameloblasts is the hardest material in the human body, acting as a shield protecting the teeth. However, enamel is gradually damaged or partially lost in over 90% of adults and cannot be regenerated due to a lack of ameloblasts in erupted teeth. Here we use sci-RNA-seq to establish a spatiotemporal single cell atlas for the developing human tooth and identify regulatory mechanisms controlling the differentiation process of human ameloblasts. We reveal key signaling pathways involved between the support cells and ameloblasts during fetal development and recapitulate those findings in a novel human ameloblast in vitro differentiation from iPSCs. We furthermore develop a mineralizing enamel organ-like 3D organoid system. These studies pave the way for future regenerative dentistry and therapies toward genetic diseases affecting enamel formation.