Dental Follicle Cells Participate in Tooth Eruption via the RUNX2-MiR-31-SATB2 Loop

Abstract

Cleidocranial dysplasia (CCD) is characterized by the runt-related transcription factor 2 (RUNX2) mutation, which results in delayed tooth eruption due to disturbed functions of dental follicle. Accumulating evidence has revealed a key regulatory circuit, including RUNX2, miR-31, and special AT-rich binding protein 2 (SATB2) acting in concert in mesenchymal stem cell homeostasis and functions. However, whether such a regulatory loop works in dental follicle cells (DFCs) remains unknown. Herein, we investigated the roles of RUNX2-miR-31-SATB2 in DFCs from patients with CCD (DFCs-CCD) to advance our understanding regarding physical tooth eruption. We identified a novel mutation on exon 5 (c.634T>G, p.T212P) in RUNX2 via exome sequencing in the CCD patient with typical clinical presentations. Compared with DFCs from healthy donors, DFCs-CCD displayed significantly lower osteogenic, osteoclast-inductive, and matrix-degrading capacities and had lower RUNX2 (a transcriptional inhibitor of miR-31), higher miR-31, and downregulated SATB2. Lower ratios of RANKL/OPG and RANKL/RANK, as well as decreased expression of matrix metalloproteinase 9 (MMP9) and matrix metalloproteinase 2 (MMP2), would lead to inactivation of osteoclasts and suppression of bone matrix remodeling in DFCs-CCD. Furthermore, the roles of the RUNX2-miR-31-SATB2 loop in DFCs-CCD were revealed by endogenous miR-31 knockdown, which resulted in increased SATB2 and RUNX2, as well as osteoclast-inductive and matrix degradation capacities. Conversely, SATB2, RUNX2, MMP9, MMP2, and osteoclast-inductive factors expression declined upon ectopic miR-31 overexpression in normal DFCs. Importantly, neonatal mice with in vivo siRUNX2 delivery exhibited less activated osteoclasts around dental follicles and delayed tooth eruption. Together, these results suggest that RUNX2 mutation/haploinsufficiency disturbs osteoclast-inductive signaling in DFCs, which may be responsible for delayed tooth eruption in CCD patients. Manipulation of the RUNX2-miR-31-SATB2 loop may be a potential way to facilitate tooth eruption in CCD patients.

MicroRNA‐31a‐5p from aging BMSCs links bone formation and resorption in the aged bone marrow microenvironment

“…The reduced protein levels of SATB2 suggested that expression of miR‐31a‐5p was negatively correlated with SATB2 levels. We used TargetScan to predict the target of miR‐31a‐5p and found that miR‐31a‐5p could bind to the 3′‐untranslated region (3′UTR) of SATB2 (Figure 3g), a pluripotency transcription factor, which has been previously demonstrated (Deng, Wu et al., 2013; Ge et al., 2015). To further demonstrate whether miR‐31a‐5p regulated osteogenesis via SATB2, the osteogenic capacity of si‐SATB2 treated BMSCs was rejuvenated by miR‐31a‐5p inhibition (Figure 3h,i).…”

“…Our previous study demonstrated that microRNA‐31a‐5p (miR‐31a‐5p) in BMSCs regulates osteogenic differentiation in tooth eruption via the SATB2 pathway (special AT‐rich binding protein 2; Ge et al., 2015). Our previous results also demonstrated that SATB2 improves the stemness capacity and osteogenic differentiation of aged human BMSCs (Zhou et al., 2016).…”

Abnormal bone remodelling activity of dental follicle cells from a cleidocranial dysplasia patient

“…However, the proliferation rate of DFCs RUNX2+/m showed no difference compared with DFCs RUNX2+/+ in the present study. Previous studies by other researchers reported that RUNX2 mutation showed conflicting role on cell proliferation (Ge et al., ; Li et al., ; Sun et al., ; Wang et al., ; Yan et al., ). We speculated that different cell type and environment among studies might be responsible for the inconsistent results.…”

Role of miR‐31 and SATB2 in arsenic‐induced malignant BEAS‐2B cell transformation

“…Of the currently available 17 studies, five have suggested that miR‐31 was an upstream negative regulator of SATB2 . Furthermore, of the seven known miR‐31 targets, SATB2 was by far the most frequently identified . Physically, miR‐31 was capable of binding to two sites in the SATB2 3′‐UTR region; Figure A demonstrates the sequences that bind with miR‐31 (miRmap: http://mirmap.ezlab.org/).…”