Nakamura Tomoaki, Iwamoto Tsutomu, Nakamura Hannah M, Shindo Yuki, Saito Kan, Yamada Aya, Yamada Yoshihiko, Fukumoto Satoshi, Nakamura Takashi
Division of Pediatric Dentistry, Department of Oral Health and Development Sciences, Tohoku University Graduate School of Dentistry, Sendai, Japan.
Department of Pediatric Dentistry, Institute of Biomedical Sciences, Tokushima University Graduate School, Tokushima, Japan.
Front Cell Dev Biol. 2020 Mar 17;8:156. doi: 10.3389/fcell.2020.00156. eCollection 2020.
Many genes encoding growth factors, receptors, and transcription factors are induced by the epithelial-mesenchymal interaction during tooth development. Recently, numerous functions of microRNAs (miRNAs) are reportedly involved in organogenesis and disease. miRNAs regulate gene expression by inhibiting translation and destabilizing mRNAs. However, the expression and function of miRNAs in tooth development remain poorly understood. This study aimed to analyze the expression of miRNAs produced during tooth development using a microarray system to clarify the role of miRNAs in dental development. miR-1 showed a unique expression pattern in the developing tooth. miR-1 expression in the tooth germ peaked on embryonic day 16.5, decreasing gradually on postnatal days 1 and 3. An hybridization assay revealed that miR-1 is expressed at the cervical loop of the dental epithelium. The expression of miR-1 and connexin (Cx) 43, a target of miR-1, were inversely correlated both and . Knockdown of miR-1 induced the expression of Cx43 in dental epithelial cells. Interestingly, cells with miR-1 downregulation proliferated slower than the control cells. Immunocytochemistry revealed that Cx43 in cells with miR-1 knockdown formed both cell-cell gap junctions and hemichannels at the plasma membrane. Furthermore, the rate of ATP release was higher in cells with miR-1 knockdown than in control cells. Furthermore, Cx43 downregulation in developing molars was observed in Epiprofin-knockout mice, along with the induction of miR-1 expression. These results suggest that the expression pattern of Cx43 is modulated by miR-1 to control cell proliferation activity during dental epithelial cell differentiation.
在牙齿发育过程中，许多编码生长因子、受体和转录因子的基因是由上皮-间充质相互作用诱导产生的。最近，据报道微小RNA（miRNA）的众多功能参与了器官发生和疾病过程。miRNA通过抑制翻译和使mRNA不稳定来调节基因表达。然而，miRNA在牙齿发育中的表达和功能仍知之甚少。本研究旨在使用微阵列系统分析牙齿发育过程中产生的miRNA的表达，以阐明miRNA在牙齿发育中的作用。miR-1在发育中的牙齿中呈现出独特的表达模式。牙胚中miR-1的表达在胚胎第16.5天达到峰值，在出生后第1天和第3天逐渐下降。杂交分析显示miR-1在牙上皮的颈环处表达。miR-1及其靶标连接蛋白（Cx）43的表达在[具体情况1]和[具体情况2]中均呈负相关。miR-1的敲低诱导了牙上皮细胞中Cx43的表达。有趣的是，miR-1下调的细胞比对照细胞增殖得慢。免疫细胞化学显示，miR-1敲低的细胞中的Cx43在质膜上形成了细胞间缝隙连接和半通道。此外，miR-1敲低的细胞中ATP释放速率高于对照细胞。此外，在Epiprofin基因敲除小鼠中观察到发育中的磨牙中Cx43下调，同时miR-1表达被诱导。这些结果表明，Cx43的表达模式受miR-1调节，以控制牙上皮细胞分化过程中的细胞增殖活性。
