Mounting evidence indicates that circular RNAs (circRNAs) have essential roles in several diseases, including periodontitis. Periodontal ligament stem cells (PDLSCs) exhibit potential for treating periodontitis accompanied by hypoxia. However, it is unclear how circRNA affects the osteogenesis of PDLSCs under hypoxia. In this study, a novel circRNA, hsa_circ_0003489, was found located at the gene for cyclin‐dependent kinase 8 (CDK8) and referred to as circCDK8. The expression levels of circCDK8 and hypoxia‐inducible factor‐1α were significantly increased in periodontitis tissues, and the expression of circCDK8 was further confirmed in a hypoxia model using cobalt chloride (CoCl2). Interestingly, the results showed that the expression levels of osteoblast markers (RUNX2, ALP, OCN, and COL1A1) were increased in CoCl2‐treated PDLSCs at 6 and 12 h, but decreased at 24, 48, and 72 h. On the basis of bioinformatics and functional experiments, CoCl2 also induced endoplasmic reticulum stress, autophagy, and apoptosis of PDLSCs; the inhibition of autophagy promoted the osteogenic differentiation of CoCl2‐treated PDLSCs. Furthermore, circCDK8 overexpression induced autophagy and apoptosis through mTOR signaling, and circCDK8 silencing reversed the inhibitory effects of CoCl2 on osteogenic differentiation of PDLSCs. In conclusion, our results indicate that circCDK8 represses the osteogenic differentiation of PDLSCs by triggering autophagy activation in a hypoxic microenvironment. CircCDK8 could be a new therapeutic target of periodontitis.
PurposeKashin-Beck disease (KBD) is an endemic degenerative osteoarthritis associated with extracellular matrix degradation. The aim of this investigation was to evaluate the role of targeting genes in the pathogenesis of KBD and primary osteoarthritis (OA) involved in extracellular matrix degradation.MethodsAgilent 44 K human whole-genome oligonucleotide microarrays were used to detect the gene expression in KBD and OA cartilage. The mRNA and protein expressions of CSGalNAcT-1 and Hapln-1 in chondrocytes were verified by reverse transcription polymerase chain reaction (RT-PCR) and western blot, and their expression in cartilage were verified with immunocytochemical analysis. Meanwhile, CSGalNAcT-1 and Hapln-1 protein levels in the selenium intervention group of KBD with different concentrations (0.25, 0.1and 0.05 μg/ml) were detected by western blot.ResultsCSGalNAcT-1 and Hapln-1 were down-regulated in KBD and OA at both mRNA and protein levels, and were increased in Se(Selenium) groups compared to KBD free-Se group. However, Wnt 3a, β-catenin and Runx-2 were up-regulated in OA and KBD at protein levels. Additionally, immunohistochemical staining showed that CSGalNAcT-1 and Hapln-1 were reduced in all zones of KBD and OA articular cartilage, but not significantly reduced in the up zone of OA articular cartilage.ConclusionsThe CSGalNAcT-1 and Hapln-1 were down-regulated in both KBD and OA cartilage. CSGalNAcT-1 may be involved in the damage of articular cartilage of KBD and OA by regulating Hapln-1 in the Wnt/β-catenin signalling pathway. It was indicated that CSGalNAcT-1 and Hapln-1 may play important roles in the pathogenesis of KBD and OA.
This meta-analysis aimed to analyze the association between CD14 C-159T and C-260T polymorphisms and periodontitis risks because previous results have been conflicting. We used 12 eligible case-control studies involving 1435 cases and 1446 controls to evaluate this association. Compared with the common CD14 C-159T and C-260T genotypes, there was no significant association of T alleles and the CT/TT genotypes polymorphism with periodontitis risk (odds ratio [OR], 1.03; 95% confidence interval [CI], 0.83-1.27 for C vs. T; OR, 1.07; 95% CI, 0.83-1.38 for CT/TT vs. CC). A similar result was found in a subgroup analysis by ethnicity and periodontitis type. An enhanced risk for periodontitis was demonstrated in the comparison of subjects carrying the CT genotype versus CC homozygotes (overall OR, 1.681; 95% CI, 1.048-2.695; P for heterogeneity=0.367; I2=2.00%) for the C-260T genotype. Our meta-analysis revealed that the 2 common CD14 polymorphisms, C-159T and C-260T, have no association with the likelihood of periodontitis. In subgroup analysis by ethnicity and periodontitis type, the results also did not show any association. The effect of genetic networks and their mutual interactions in the CD14 signaling pathway on susceptibility to periodontitis need to be studied further.
Background Gremlin has been reported to regulate inflammation and osteogenesis. Periodontitis is a destructive disease degenerating periodontal tissues, therefore leads to alveolar bone resorption and tooth loss. Based on the importance of Gremlin's bio‐activity, the aim of this study is to, in vivo and in vitro, unveil the function of Gremlin in regulating the development of periodontitis and its consequent effects on alveolar bone loss. Methods Clinical specimens were used to determine the expression of Gremlin in periodontal tissues by immunohistochemical staining and western blot. Then utilizing the rat periodontitis model to investigate the function of gremlin‐regulated nuclear factor‐kappa B (NF‐κB) pathway during the development of periodontal inflammation and the alveolar bone loss. Last, the regulation of the osteogenesis of human periodontal ligament stem cells (hPDLSCs) by Gremlin under inflamed condition was analyzed by alkaline phosphatase (ALP) and alizarin red staining (ARS). Results We found clinically and experimentally that the expression of Gremlin is markedly increased in periodontitis tissues. Interestingly, we revealed that Gremlin regulated the progress of periodontitis via regulating the activities of NF‐κB pathway and interleukin‐1β (IL‐1β). Notably, we observed that Gremlin influenced the osteogenesis of hPDLSCs. Thus, our present study identified Gremlin as a new key regulator for development of periodontitis. Conclusions Our current study illustrated that Gremlin acts as a crucial mediator and possibly serves as a potential diagnostic marker for periodontitis. Discovery of new factors involved in the pathophysiology of periodontitis could contribute to the development of novel therapeutic treatment for the disease.
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