USP34 regulates tooth root morphogenesis by stabilizing NFIC / 国际口腔科学杂志·英文版

Tooth root morphogenesis involves two biological processes, root elongation and dentinogenesis, which are guaranteed by downgrowth of Hertwig's epithelial root sheath (HERS) and normal odontoblast differentiation. Ubiquitin-dependent protein degradation has been reported to precisely regulate various physiological processes, while its role in tooth development is still elusive. Here we show ubiquitin-specific protease 34 (USP34) plays a pivotal role in root formation. Deletion of Usp34 in dental mesenchymal cells leads to short root anomaly, characterized by truncated roots and thin root dentin. The USP34-deficient dental pulp cells (DPCs) exhibit decreased odontogenic differentiation with downregulation of nuclear factor I/C (NFIC). Overexpression of NFIC partially restores the impaired odontogenic potential of DPCs. These findings indicate that USP34-dependent deubiquitination is critical for root morphogenesis by stabilizing NFIC.

AFF4 regulates osteogenic differentiation of human dental follicle cells / 国际口腔科学杂志·英文版

As a member of the AFF (AF4/FMR2) family, AFF4 is a transcription elongation factor that is a component of the super elongation complex. AFF4 serves as a scaffolding protein that connects transcription factors and promotes gene transcription through elongation and chromatin remodelling. Here, we investigated the effect of AFF4 on human dental follicle cells (DFCs) in osteogenic differentiation. In this study, we found that small interfering RNA-mediated depletion of AFF4 resulted in decreased alkaline phosphatase (ALP) activity and impaired mineralization. In addition, the expression of osteogenic-related genes (DLX5, SP7, RUNX2 and BGLAP) was significantly downregulated. In contrast, lentivirus-mediated overexpression of AFF4 significantly enhanced the osteogenic potential of human DFCs. Mechanistically, we found that both the mRNA and protein levels of ALKBH1, a critical regulator of epigenetics, changed in accordance with AFF4 expression levels. Overexpression of ALKBH1 in AFF4-depleted DFCs partially rescued the impairment of osteogenic differentiation. Our data indicated that AFF4 promoted the osteogenic differentiation of DFCs by upregulating the transcription of ALKBH1.

Effect of estrogen deficiency on the expression levels of nuclear factor-kappa B and interleukin-17 in periodontal tissues / 中国组织工程研究

BACKGROUND:There is a very close relationship between osteoporosis and periodontal disease in postmenopausal women, but the mechanism remains unclear. OBJECTIVE:To investigate the expression of nuclear factor-κB in the alveolar bone andinterleukin-17 in the serum and gingiva in the mouse model of osteoporosis caused by ovariectomy. METHODS:Female mice aged 3 months were randomly divided into ovariectomy and sham operation groups. At 6 months after surgery, the mouse models were evaluated histologically on the submandibular bone and thigh bone stained with hematoxylin and eosin. In the submandibular bone, the expression levels of OCN and Runx2 were detected by RT-PCR, and the expression level of nuclear factor-κB was detected by immunohistochemical staining and western blot assay. Besides, the expression level of interleukin-17 in the serum and gingival homogenate was evaluated using Cytometric Beads Array. RESULTS AND CONCLUSION:The thigh bone in the ovariectomy group revealed the thin cortical bone, enlarged marrow cavity, and increased resorption lacunae, as well as fewer, thinner trabeculae with lower density and irregular structure. Compared with the sham operation group, the expression levels of OCN and Runx2 in the alveolar bone were decreased in the ovariectomy group. The activation of nuclear factor-κB (P65)appeared with P65 positive expression in the submandibular bone in the ovariectomy group, and the relative expression level was higher than that in the sham operation group. The serum level of interleukin-17 in the ovariectomy group was higher than that in the sham operation group, but the level in the gingival tissue showed no significant difference between the two groups. These results indicate that estrogen deficiency after ovariectomy can activate nuclear factor-κB signal pathway to play a role in periodontal osteolysis. However interleukin-17 in the local periodontal tissue may not be a key cytokine to damage the periodontal tissue.