microRNA-875-5p plays critical role for mesenchymal condensation in epithelial-mesenchymal interaction during tooth development

Abstract

Epithelial-mesenchymal interaction has critical roles for organ development including teeth, during which epithelial thickening and mesenchymal condensation are initiated by precise regulation of the signaling pathway. In teeth, neural crest-derived mesenchymal cells expressed PDGF receptors migrate and become condensed toward invaginated epithelium. To identify the molecular mechanism of this interaction, we explored the specific transcriptional start sites (TSSs) of tooth organs using cap analysis of gene expression (CAGE). We identified a tooth specific TSS detected in the chromosome 15qD1 region, which codes microRNA-875 (mir875). MiR875-5p is specifically expressed in dental mesenchyme during the early stage of tooth development. Furthermore, PRRX1/2 binds to the mir875 promoter region and enhances the expression of mir875. To assess the role of miR875-5p in dental mesenchyme, we transfected mimic miR875-5p into mouse dental pulp (mDP) cells, which showed that cell migration toward dental epithelial cells was significantly induced by miR875-5p via the PDGF signaling pathway. Those results also demonstrated that miR875-5p induces cell migration by inhibiting PTEN and STAT1, which are regulated by miR875-5p as part of post-transcriptional regulation. Together, our findings indicate that tooth specific miR875-5p has important roles in cell condensation of mesenchymal cells around invaginated dental epithelium and induction of epithelial-mesenchymal interaction. Tooth morphogenesis, initiated by reciprocal interactions between the ectoderm and neural crest-derived mesenchyme 1-3 , is a good model for understanding the molecular mechanism of epithelial-mesenchymal interaction, because of the well-defined developmental stages and distinctive cell types. In mice, that morphogenesis is initiated by thickening of dental epithelium to form the dental placode, followed by invagination into mesenchyme on embryonic day (E)11.5. In addition, neural crest-derived mesenchymal cells migrate and condense toward the dental epithelial placode. Thereafter, mesenchyme condenses around the epithelial tooth bud and gains an ability for tooth morphogenesis via expression of a particular set of transcription factors and signaling molecules 3,4. During tooth morphogenesis, invaginated epithelium and condensed mesenchymal tissues interact with each other (epithelial-mesenchymal interaction), and form the shape of the tooth. Finally, dental epithelium and mesenchyme differentiate into ameloblasts, which secretes enamel, and odontoblasts, secreting dentin. However, the molecular mechanism of mesenchymal cell migration and condensation have yet to be clearly elucidated. Cranial skeletal tissues including tooth, bone, nerves, and blood vessels are mainly derived from neural crest cells (NCCs) 5-7. The neural crest is composed of transient embryonic tissues present during neural tube formation, whose cells have a high potential for migration and differentiation 7-9. Disruption of cranial NCC migration during embryonic development can lead t...

The Regulatory Role of PRRX1 in Cancer Epithelial-Mesenchymal Transition

“…In melanoma progression, PRRX1 was found upregulated and negatively correlated with miR-485-5p. 6 Wu et al found that miR-485-5p can target PRRX1 to silence its expression. As a result, inhibiting the progress of EMT.…”

“…For instance, PRRX1 can bind to the promoter region of MIR875 at −500 to +100 nts, especially the sequence of “TAATTA” at about −192 nts, which stimulates the maturation of miR-875-5p and promotes the migration of tumor cells. 6 Interestingly, Jiang et al found that PRRX1 bonded to the hypoxia response element regions of pre-miR-642b to inhibit the maturation of miR-642b-3p, which inhibited the EMT of tumor cells. 26 …”

“…4 As a transcription co-activator, PRRX1 can bind to PRRX2 in order to regulate MIR875 at the 5′-AATTA-3′ region of its promoter. 6 Also, PRRX1 can interact with serum response factor (SRF) and SRF-Phox1 interacting protein (SPIN) to bond to the promoter of FOS at the 5′-GTCAAT-3′region. 7 PRRX1 is abnormally expressed in many diseases and is involved in tumor metastasis.…”

Expression Patterns of Claudin Family Members During Tooth Development and the Role of Claudin-10 (Cldn10) in Cytodifferentiation of Stratum Intermedium

“…RNA quality was verified using an Agilent Bioanalyzer System (Agilent, Pal Alto, CA, United States), with the results revealing an RNA integrity number (RIN) >8.5 for all the samples. CAGE was performed by DNAFORM (Yokohama, Japan) as previously described (Funada et al, 2020).…”

“…Cldn10 may be expressed as two splice variants, Cldn10a and Cldn10b, which exhibit different expression patterns in organs. Utilizing the CAGE data, tooth-specific transcriptional start sites were explored, as previously described (Funada et al, 2020). The CAGE dataset obtained from mouse tooth germs revealed that only Cldn10b showed a high peak in tooth samples (Figure 2A).…”