Comparison of transcriptomes of pre-ameloblasts (PAB) and secretory ameloblasts (SAB) in tooth development

Ameloblast differentiation is the most critical stepwise process in amelogenesis, and it is controlled by precise molecular events. To better understand the mechanism controlling pre-ameloblasts (PABs) differentiation into secretory ameloblasts (SABs), a more precise identification of molecules and signaling networks will elucidate the mechanisms governing enamel formation and lay a foundation for enamel regeneration. We analyzed transcriptional profiles of human PABs and SABs. From a total of 28,869 analyzed transcripts, we identified 923 differentially expressed genes (DEGs) with p < 0.05 and Fold-change > 2. Among the DEGs, 647 genes showed elevated expression in PABs compared to SABs. Notably, 38 DEGs displayed more than eight-fold changes. Comparative analysis revealed that highly expressed genes in PABs were involved in cell cycle control, DNA damage repair and apoptosis, while highly expressed genes in SABs were related to cell adhesion and extracellular matrix. Moreover, coexpression network analysis uncovered two highly conserved sub-networks contributing to the differentiation, containing transcription regulators (RUNX2, ETV1 and ETV5), solute carrier family members (SLC15A1 and SLC7A11), enamel matrix protein (MMP20), and a polymodal excitatory ion channel (TRPA1). By combining comparative analysis and coexpression networks, this study provides novel biomarkers and research targets for ameloblast differentiation and the potential for their application in enamel regeneration. Human tooth buds (18-22 weeks) were obtained from fetal cadaver tissue within 3 hours after legal abortion. Teeth were dissected from the mandibles under a laminar flow hood, embedded in OCT compound, and cryosectioned at 10-μm thickness. These sections were used for laser capture microdissection (LCM). In total of 3 pre-ameloblasts and 3 secretory ameloblasts pooled samples were used for RNA extraction and hybridization on Affymetrix microarray.