A comparison of microRNA profiles between rat incisors and molars

Abstract

Unlike the molar, rodent incisor is a distinct organ that have continuously growth at distal end of tooth throughout its lifetime to compensate for abrasion. The key of continuous growth is the result of delayed root formation and prolonged crown formation that possibly made by stem cell niche, so-called cervical loop, which involve various genes and signaling pathways. MicroRNAs (miRNAs) are small non-coding single stranded RNAs that involved in biological mechanisms of dental development. To study the role of miRNA, we extracted total RNA from the dental pulp tissue collected from the apical part, coronal part of incisors and molars, and compared the expression of miRNAs. The customized RT-PCR array (Qiagen) demonstrated that 6 miRNAs (miR-32-5p, 885-5p, 665, 338-3p, 663a, 200a-3p) in apical part and 4 miRNAs (miR-32-5p, 665, 338-3p, 663a) from coronal part are significantly lower than molar group whereas miR-23a-3p is the only one that has significantly increase in both apical and coronal part compare to the molars group. Previous studies also found role of these miRNAs that involved in both amelogenesis and dentinogenesis included DSPP, RUNX2, Wnt/β-catenin, E-cadherin and Sprouty2 genes. The results suggested that these miRNAs may have a role in mineralization process during prolonged crown formation of rodent incisors.