LncRNA-TWIST1 Promoted Osteogenic Differentiation Both in PPDLSCs and in HPDLSCs by Inhibiting TWIST1 Expression. Biomed Res Int. 2019;2019:8735952. [PMID: 31341908 PMCID: PMC6612385 DOI: 10.1155/2019/8735952]

Melatonin and oral diseases: possible therapeutic roles based on cellular mechanisms

Oral diseases, including periodontal disorders, oral cancer, periodontitis, and mucositis are the major challenges for both patients and healthcare providers. These conditions often involve inflammation, oxidative stress, and impaired cellular processes, leading to symptoms ranging from discomfort to severe debilitation. Conventional treatments for such oral diseases exhibit constraints, prompting the investigation of innovative therapeutic approaches. Considering the anti-inflammatory, anti-oxidant, and anti-cancer effects of melatonin, this study was carried out to investigate the potential protective effects of melatonin in mitigating the severity of oral diseases. Studies indicate that melatonin influences the differentiation of periodontal stem cells, inhibits oral cancer progression, reduces inflammation associated with periodontitis, and alleviates the severity of oral mucositis. Melatonin has demonstrated potential efficacy in both preclinical and clinical investigations; however, findings are frequently heterogeneous and contingent upon contextual factors. This review provides a comprehensiveoverview of current state of knowledge in this domain, elucidating the multifaceted role that melatonin may assume in combatingoral diseases. Further research should be directed toward determining the most effective dosing, timing, and administration methods for melatonin-based therapies for oral diseases.

LncRNA in periodontal tissue-derived cells on osteogenic differentiation in the periodontitis field

OBJECTIVE

Periodontitis can lead to the destruction of periodontal tissues and potentially tooth loss. Numerous periodontal tissue-derived cells display osteogenic differentiation potential. The presence of differentially expressed long non-coding RNAs (lncRNAs) in these cells indicate their ability to regulate the process of osteogenic differentiation. We aim to elucidate the various lncRNA-mediated regulatory mechanisms in the osteogenic differentiation of periodontal tissue-derived cells in the field of periodontitis at epigenetic modification, transcriptional, and post-transcriptional levels.

SUBJECTS AND METHODS

We systematically searched the PubMed, Web of Science, and ScienceDirect databases to identify relevant literature in the field of periodontitis discussing the role of lncRNAs in regulating osteogenic differentiation of periodontal tissue-derived cells. The identified literature was subsequently summarized for comprehensive review.

RESULTS

In this review, we have comprehensively summarized the regulatory mechanisms of lncRNAs in the osteogenic differentiation of periodontal tissue-derived cells in the field of periodontitis and discussed how these lncRNAs provide novel perspectives for understanding the pathogenesis and progression of periodontitis.

CONCLUSION

These results indicate the pivotal role of lncRNAs as regulators in the osteogenic differentiation of periodontal tissue-derived cells, providing a solid basis for future investigations on the role of lncRNAs in the periodontitis field.

LncRNA urothelial cancer associated 1 promotes the osteogenic differentiation of human periodontal ligament stem cells by regulating the miR-96-5p/Osx axis

OBJECTIVES

To investigate the expression of long non-coding RNA (lncRNA) urothelial cancer associated 1 (UCA1) in human periodontal ligament stem cells (hPDLSCs), its effect on osteogenic differentiation of hPDLSCs and its mechanism.

DESIGN

The expression of osteogenic genes Osx, Runx2, Ocn and Opn was explored by qPCR. Protein expression in hPDLSCs was estimated by Western blot. The osteogenic differentiation of hPDLSCs was detected by Alizarin red staining assays. The interaction between UCA1 and miR-96-5p was explored by RNA pulldown assay and dual luciferase assay. The interaction between miR-96-5p and Osx 3'-UTR was measured by dual luciferase assay.

RESULTS

The expression of UCA1 and miR-96-5p was negatively correlated in hPDLSCs. During the osteogenic differentiation of hPDLSCs, the expression of UCA1 was increased, while the expression of miR-96-5p was decreased. Knockdown of UCA1 in hPDLSCs inhibited osteogenic differentiation but induced upregulation of miR-96-5p expression, and vice versa. In addition, miR-96-5p partially reversed the positive effect of UCA1 on osteogenic differentiation of hPDLSCs. Notably, UCA1 was identified as a miR-96-5p sponge, and miR-96-5p targeted Osx.

CONCLUSIONS

Our results demonstrated that the novel UCA1/miR-96-5p/Osx pathway regulates osteogenic differentiation of hPDLSCs and sheds new insights and targets for periodontitis therapeutics.

METTL3-Mediated m6A Modification Regulates the Osteogenic Differentiation through LncRNA CUTALP in Periodontal Mesenchymal Stem Cells of Periodontitis Patients

Objective

Periodontitis is a chronic inflammatory disease that causes loss of periodontal support tissue. Our objective was to investigate the mechanism by which METTL3-mediated N6-methyladenosine modification regulates the osteogenic differentiation through lncRNA in periodontal mesenchymal stem cells in patients with periodontitis (pPDLSCs). Material and Methods. We carried out a series of experiments, including methylated RNA immunoprecipitation-PCR, quantitative real-time polymerase chain reaction, and western blotting. The expressions of alkaline phosphatase (ALP), Runx2, Col1, Runx2 protein level, ALP staining, and Alizarin red staining were used to demonstrate the degree of osteogenic differentiation.

Results

We found that METTL3 was the most significantly differentially expressed methylation-related enzyme in pPDLSCs and promoted osteogenic differentiation of pPDLSCs. METTL3 regulated the stability and expression of lncRNA CUTALP, while lncRNA CUTALP promoted osteogenic differentiation of pPDLSCs by inhibiting miR-30b-3p. At different time points of osteogenic differentiation, lncRNA CUTALP expression was positively correlated with Runx2, while miR-30b-3p showed the opposite pattern. The attenuated osteogenic differentiation induced by METTL3 knockdown was recovered by lncRNA CUTALP overexpression. The attenuated osteogenic differentiation induced by lncRNA CUTALP knockdown could be reversed by the miR-30b-3p inhibitor.

Conclusions

In summary, METTL3/lncRNA CUTALP/miR-30b-3p/Runx2 is a regulatory network in the osteogenic differentiation of pPDLSCs.

Decoding the role of long non-coding RNAs in periodontitis: A comprehensive review

Periodontitis is an inflammatory disease characterized by the pathological loss of alveolar bone and the adjacent periodontal ligament. It is considered a disease that imposes a substantial health burden, with an incidence rate of 20-50%. The etiology of periodontitis is multifactorial, with genetic factors accounting for approximately half of severe cases. Studies have revealed that long non-coding RNAs (lncRNAs) play a pivotal role in periodontitis pathogenesis. Accumulating evidence suggests that lncRNAs have distinct regulatory mechanisms, enabling them to control numerous vital processes in periodontal cells, including osteogenic differentiation, inflammation, proliferation, apoptosis, and autophagy. In this review, we summarize the diverse roles of lncRNAs in the pathogenesis of periodontitis, shedding light on the underlying mechanisms of disease development. By highlighting the potential of lncRNAs as biomarkers and therapeutic targets, this review offers a new perspective on the diagnosis and treatment of periodontitis, paving the way for further investigation into the field of lncRNA-based therapeutics.

Long Noncoding RNA and mRNA m6A Modification Analyses of Periodontal Ligament Stem Cells from the Periodontitis Microenvironment Exposed to Static Mechanical Strain

Periodontal ligament stem cells (PDLSCs) play important roles in orthodontic tooth movement (OTM) and can respond to mechanical stress. Our previous study demonstrated that periodontal ligament stem cells derived from periodontitis tissue (pPDLSCs) are more sensitive to static mechanical strain (SMS) than those derived from healthy tissue (hPDLSCs) and reported the long noncoding RNA (lncRNA) expression profiles of pPDLSCs exposed to SMS. An increasing number of lncRNAs have been reported by various studies to be associated with the osteogenic differentiation of mesenchymal stem cells. Many studies have demonstrated that the n6-methyladenosine (m6A) modification exerts important effects on lncRNA and mRNA regulation of cell behaviors. However, the regulatory effects of lncRNA and mRNA m6A modification on PDLSCs have not been studied. Therefore, we performed an m6A microarray assay with pPLDSCs and hPDLSCs exposed to 12% SMS and found that 143 lncRNAs and 739 mRNAs were differentially methylated. These RNAs were thought to be involved in multiple differentiation and inflammatory responses. Moreover, we found that METTL3, an essential protein in the m6A system, was expressed at lower levels in the strain-exposed pPDLSCs than in strain-exposed hPLDSCs, and METTL3 promoted the osteogenic differentiation of pPDLSCs.

Emerging role of epigenetic regulations in periodontitis: a literature review

Periodontitis is mainly initiated by periodontal pathogens including Porphyromonas gingivalis, and bad living habits such as smoking aggravate its incidence and severity. The development of periodontitis is closely related to the host's immune responses and the secretion of various cytokine networks. Moreover, periodontitis has an important connection with the development of systemic diseases. Recently, epigenetics which is a fast-developing hot research area has provided new insights into the research of various diseases including periodontitis. Epigenetics is an important supplement to the regulation of gene expression. The study of epigenetics is about causing heritable gene expression or cell phenotype changes through certain mechanisms without changing the DNA sequence. It mainly includes histone modification, DNA methylation, non-coding RNA and the latest research hotspot m6A RNA methylation. In the review, we comprehensively summarize the latest literature on the potential epigenetic regulations in various aspects of periodontitis.

The Expression and Regulatory Roles of Long Non-Coding RNAs in Periodontal Ligament Cells: A Systematic Review

Periodontal ligament (PDL) cells play a pivotal role in periodontal and bone homeostasis and have promising potential for regenerative medicine and tissue engineering. There is compelling evidence that long non-coding RNAs (lncRNAs) are differentially expressed in PDL cells compared to other cell types and that these lncRNAs are involved in a variety of biological processes. This study systematically reviews the current evidence regarding the expression and regulatory functions of lncRNAs in PDL cells during various biological processes. A systematic search was conducted on PubMed, the Web of Science, Embase, and Google Scholar to include articles published up to 1 July 2021. Original research articles that investigated the expression or regulation of lncRNAs in PDL cells were selected and evaluated for a systematic review. Fifty studies were ultimately included, based on our eligibility criteria. Thirteen of these studies broadly explored the expression profiles of lncRNAs in PDL cells using microarray or RNA sequencing. Nineteen studies investigated the mechanisms by which lncRNAs regulate osteogenic differentiation in PDL cells. The remaining 18 studies investigated the mechanism by which lncRNAs regulate the responses of PDL cells to various stimuli, namely, lipopolysaccharide-induced inflammation, tumor necrosis factor alpha-induced inflammation, mechanical stress, oxidative stress, or hypoxia. We systematically reviewed studies on the expression and regulatory roles of lncRNAs in diverse biological processes in PDL cells, including osteogenic differentiation and cellular responses to inflammation, mechanical stress, and other stimuli. These results provide new insights that may guide the development of lncRNA-based therapeutics for periodontal and bone regeneration.

MicroRNA-149 suppresses osteogenic differentiation of mesenchymal stem cells via inhibition of AKT1-dependent Twist1 phosphorylation

Osteogenic differentiation is a vital process for growth, repair, and remodeling of bones. Accumulating evidence have suggested that microRNAs (miRNAs or miRs) play a crucial role in osteogenic differentiation of mesenchymal stem cells (MSCs). Hence, the current study set out to elucidate the role of miR-149 in osteogenic differentiation of MSCs and the underlying mechanism. First, rat models of bone differentiation were established using the Masquelet-induced membrane technique, and MSCs were isolated. The expression of miR-149 and AKT1 in the rats and cells was detected with RT-qPCR and western blot analysis. The relationships among miR-149, AKT1, and Twist1 were further predicted by online bioinformatics prediction and verified using dual luciferase reporter gene assay. Alteration of miR-149, AKT1, or Twist1 was performed to further explore their effect on osteogenic differentiation of MSCs. miR-149 was poorly expressed in the process of osteogenic differentiation of MSCs, while AKT1 was highly expressed. miR-149 negatively regulated the expression of AKT1, which in turn diminished the protein levels of Twist1 and promoted the phosphorylation levels of Twist1. Lastly, miR-149 acted as an inhibitor of osteogenic differentiation of MSCs, which could be reversed by AKT1. To sum up, miR-149 silencing promoted osteogenic differentiation of MSCs by enhancing Twist1 degradation through AKT1 upregulation, representing a new method for bone repair treatment.

Downregulation of lncRNA ANRIL Inhibits Osteogenic Differentiation of Periodontal Ligament Cells via Sponging miR-7 through NF-κB Pathway

BACKGROUND

Long noncoding RNAs (lncRNAs) are dysregulated in periodontitis development and involved in osteogenesis. The current study was aimed at investigating the function of lncRNA ANRIL in periodontal ligament cells (PDLCs) and potential molecular mechanisms.

METHODS

Firstly, the level of ANRIL was tested by qPCR. Then, PDLCs were treated with a mineralizing solution to induce osteogenic differentiation. ALP activity was measured, and protein levels of BMP2, Osterix, and OCN were measured by Western blot. A target of ANRIL was verified using dual-luciferase reporter assay. miR-7 level was measured by qPCR, and the signals of the NF-κB pathway were tested by Western blot.

RESULTS

ANRIL expression was downregulated in PDL tissues. Next, ALP activity and protein levels of BMP2, Osterix, and OCN were increased to show that PDLCs were differentiated. ANRIL level was increased in differential PDLCs, in which knockdown inhibited osteogenic differentiation. Then, miR-7 was found as a target of ANRIL. The miR-7 level was upregulated in PDL tissues and reduced in differential PDLCs. Inhibition of miR-7 suppressed ALP activity and BMP2, Osterix, and OCN expression. Moreover, inhibition of miR-7 reversed the effects on the osteogenic differentiation induced by knockdown of ANRIL. Besides, the levels of p-P65 and p-IκBα were elevated by ANRIL downregulation and were rescued by suppressing miR-7.

CONCLUSIONS

Knockdown of ANRIL inhibited osteogenic differentiation via sponging miR-7 through the NF-κB pathway, suggesting that ANRIL might be a therapeutic target for periodontitis.

Long non-coding RNA potassium voltage-gated channel subfamily Q member 1 overlapping transcript 1 regulates the proliferation and osteogenic differentiation of human periodontal ligament stem cells by targeting miR-24-3p

OBJECTIVES

This study aims to explore the effect and molecular mechanism of long non-coding RNA (lncRNA) potassium voltage-gated channel subfamily Q member 1 overlapping transcript 1 (KCNQ1OT1) on proliferation and osteogenic differentiation in human periodontal ligament stem cells (hPDLSCs).

METHODS

The hPDLSCs of normal periodontal tissues were isolated and cultured. The mineralized solution induced the osteoblast differentiation of hPDLSCs. The down-regulation of lncRNA KCNQ1OT1, the overexpression of anti-miR-24-3p on the proliferation and the levels of osteocalcin (OCN), osteopontin (OPN) and alkaline phosphatase (ALP) of hPDLSCs were investigated. Real-time quantitative polymerase chain reaction (RT-qPCR) was used to detect the levels of lncRNA KCNQ1OT1, miR-24-3p, OCN, OPN, and ALP. Methyl thiazolyl tetrazolium (MTT) method was used to detect cell viability and activity. Cell proliferation was evaluated by MTT. Western blot was used to detect protein expression. The targeted relationship between lncRNA KCNQ1OT1 and miR-24-3p was detected by double-luciferase experiment.

RESULTS

The expression level of lncRNA KCNQ1OT1 increased, and that of miR-24-3p decreased during the osteogenesis of hPDLSCs (P<0.05). The down-regulation of lncRNA KCNQ1OT1 inhibited cell proliferation and reduced the mRNA and protein expression levels of OCN, OPN, and ALP (P<0.05). LncRNA KCNQ1OT1 targeted and regulated miR-24-3p. The overexpression of miR-24-3p inhibited cell proliferation and reduced the mRNA and protein expression levels of OCN, OPN, and ALP (P<0.05). Inhibition of miR-24-3p reversed the effect of the down-regulation of lncRNA KCNQ1OT1 on cell proliferation and mRNA and protein expression levels of OCN, OPN, and ALP (P<0.05).

CONCLUSIONS

Down-regulation of lncRNA KCNQ1OT1 inhibited the proliferation and osteogenic differentiation of hPDLSCs by targeting the up-regulated expression of miR-24-3p.

Dysregulation of lncRNAs in circulation of patients with periodontitis: results of a pilot study

Background

Periodontitis is a chronic inflammatory disorder with a complex etiology. Long non-coding RNAs (lncRNAs) have been shown to affect pathoetiology of periodontitis. We aimed at identification of expression of five lncRNAs, namely Linc0116, Linc00667, CDK6-AS1, FENDRR and DIRC3 in the circulation and gingival tissues of these patients compared with healthy controls.

Methods

In a pilot case–control study, we compared expressions of Linc0116, Linc00667, CDK6-AS1, FENDRR and DIRC3 lncRNAs between blood and tissue samples of patients with periodontitis and healthy controls using real time quantitative PCR technique. The present work was performed on samples got from 26 patients with periodontitis and 28 controls. Female/male ratio was 16/10 and 12/16 in cases and controls, respectively.

Results

There was no significant difference in the expressions of Linc0116, Linc00667, CDK6-AS1, FENDRR and DIRC3 genes between affected and unaffected tissues. However, expressions of Linc0116, Linc00667, CDK6-AS1, FENDRR and DIRC3 genes were significantly lower in the blood samples of patients when compared with control samples (Ratio of mean expression = 0.16, 0.14, 0.13, 0.10 and 0.14, respectively). Subsequently, we compared expressions of these lncRNAs between patients and controls in a sex-based manner. Expressions of Linc00667, FENDRR and DIRC3 genes were significantly lower in female patients compared with female controls (RME = 0.09, 0.07 and 0.10, respectively). Yet, there was no significant difference in expression of any of mentioned lncRNAs among male subgroups. Consistent with the similar levels of Linc0116, Linc00667, CDK6-AS1, FENDRR and DIRC3 in tissue samples of patients and controls, none of them could separate these two sets of samples. However, AUC values for of Linc0116, Linc00667, CDK6-AS1, FENDRR and DIRC3 expression levels in blood samples were 0.66, 0.72, 0.70, 0.72, 0.70 and 0.68, respectively with FENDRR having the best sensitivity value.

Conclusion

Taken together, lncRNAs might be involved in the pathologic events in the circulation of patients with periodontitis.

Contribution of miRNAs and lncRNAs in osteogenesis and related disorders

Non-coding RNAs have been found to regulate several developmental processes among them is osteogenesis. Although these transcripts have several distinct classes, two classes i.e. microRNAs and long non-coding RNAs have attained more attention. These transcripts regulate intramembranous as well as endochondral ossification processes. The effects of microRNAs on osteogenesis are mostly mediated through modulation of Wnt/β-catenin and TGFβ/BMP pathways. Long non-coding RNAs can directly affect expression of these pathways or osteogenic transcription factors. Moreover, they can serve as a molecular sponge for miRNAs. MALAT1/miR-30, MALAt1/miR-214, LEF1-AS1/miR-24-3p, MCF2L-AS1/miR-33a, MSC-AS1/miR-140-5p and KCNQ1OT1/miR-214 are examples of such kind of interaction between lncRNAs and miRNAs in the context of osteogenesis. In the current paper, we explain these two classes of non-coding RNAs in the osteogenesis and related disorders.

Long non-coding RNAs: Emerging roles in periodontitis

Periodontitis is a major burden of public health, affecting 20%-50% of the global population. It is a complex inflammatory disease characterized by the destruction of supporting structures of the teeth, leading to tooth loss and the emergence or worsening of systematic diseases. Understanding the molecular mechanisms underlying the physiopathology of periodontitis is beneficial for targeted therapeutics. Long non-coding RNAs (lncRNAs), transcripts made up of more than 200 nucleotides, have emerged as novel regulators of many biological and pathological processes. Recently, an increasing number of dysregulated lncRNAs have been found to be implicated in periodontitis. In this review, an overview of lncRNAs, including their biogenesis, characteristics, function mechanisms and research approaches, is provided. And we summarize recent research reports on the emerging roles of lncRNAs in regulating proliferation, apoptosis, inflammatory responses, and osteogenesis of periodontal cells to elucidate lncRNAs related physiopathology of periodontitis. Furthermore, we have highlighted the underlying mechanisms of lncRNAs in periodontitis pathology by interacting with microRNAs. Finally, the potential clinical applications, current challenges, and prospects of lncRNAs as diagnostic and prognostic biomarkers and therapeutic targets for periodontitis disease are discussed.

Periodontal ligament stem cells in the periodontitis niche: inseparable interactions and mechanisms

Periodontitis is characterized by the periodontium's pathologic destruction due to the host's overwhelmed inflammation to the dental plaque. The bacterial infections and subsequent host immune responses have shaped a distinct microenvironment, which generally affects resident periodontal ligament stem cells (PDLSCs). Interestingly, recent studies have revealed that impaired PDLSCs may also contribute to the disturbance of periodontal homeostasis. The putative vicious circle underlying the interesting "positive feedback" of PDLSCs in the periodontitis niche remains a hot research topic, whereas the inseparable interactions between resident PDLSCs and the periodontitis niche are still not fully understood. This review provides a microscopic view on the periodontitis progression, especially the quick but delicate immune responses to oral dysbacterial infections. We also summarize the interesting crosstalk of the resident PDLSCs with their surrounding periodontitis niche and potential mechanisms. Particularly, the microenvironment reduces the osteogenic properties of resident PDLSCs, which are closely related to their reparative activity. Reciprocally, these impaired PDLSCs may disrupt the microenvironment by aggravating the host immune responses, promoting aberrant angiogenesis, and facilitating the osteoclastic activity. We further recommend that more in-depth studies are required to elucidate the interactions of PDLSCs with the periodontal microenvironment and provide novel interventions for periodontitis.

Multidifferentiation potential of dental-derived stem cells

Tooth-related diseases and tooth loss are widespread and are a major public health issue. The loss of teeth can affect chewing, speech, appearance and even psychology. Therefore, the science of tooth regeneration has emerged, and attention has focused on tooth regeneration based on the principles of tooth development and stem cells combined with tissue engineering technology. As undifferentiated stem cells in normal tooth tissues, dental mesenchymal stem cells (DMSCs), which are a desirable source of autologous stem cells, play a significant role in tooth regeneration. Researchers hope to reconstruct the complete tooth tissues with normal functions and vascularization by utilizing the odontogenic differentiation potential of DMSCs. Moreover, DMSCs also have the ability to differentiate towards cells of other tissue types due to their multipotency. This review focuses on the multipotential capacity of DMSCs to differentiate into various tissues, such as bone, cartilage, tendon, vessels, neural tissues, muscle-like tissues, hepatic-like tissues, eye tissues and glands and the influence of various regulatory factors, such as non-coding RNAs, signaling pathways, inflammation, aging and exosomes, on the odontogenic/osteogenic differentiation of DMSCs in tooth regeneration. The application of DMSCs in regenerative medicine and tissue engineering will be improved if the differentiation characteristics of DMSCs can be fully utilized, and the factors that regulate their differentiation can be well controlled.

LGALS3BP/Gal-3 promotes osteogenic differentiation of human periodontal ligament stem cells

OBJECTIVE

To identify the role of LGALS3BP/Gal-3 in the process of human periodontal ligament stem cells (hPDLSCs) differentiating into osteoblasts.

METHODS

IP-WB experiments were carried out to examine the binding of LGALS3BP and Gal-3. Western blot was performed to detect the expressions of LGALS3BP and Gal-3 in hPDLSCs with or without osteogenic differentiation inducement. The expressions of differentiation-related Oct4, Sox2 and Runx2 were also detected by western blot. Alkaline Phosphatase (ALP) Assay Kit was used to measure ALP activity in hPDLSCs. The mineralization ability of hPDLSCs was observed by staining with Alizarin Red S solution.

RESULTS

LGALS3BP bound with Gal-3 in hPDLSCs, and the expression of LGALS3BP and Gal-3 was improved after osteogenic differentiation of hPDLSCs. Recombinant GAL-3 promoted the expression of differentiation-related proteins Oct4 and Sox2 and Runx2 in osteogenic differentiation-induced hPDLSCs. Recombinant GAL-3 also promoted the differentiation of osteogenesis-induced hPDLSCs. Furthermore, LGALS3BP had a facilitating effect on differentiation-related protein expression, while it could be reversed by shGal-3. LGALS3BP also promoted osteogenic capacity of hPDLSCs, and shGal-3 could reverse this effect.

CONCLUSION

LGALS3BP binds to Gal-3, producing a promoting effect on the osteogenic differentiation of human periodontal ligament stem cells.

Mechanism of Cyclic Tensile Stress in Osteogenic Differentiation of Human Periodontal Ligament Stem Cells

Human periodontal ligament stem cells (hPDLSCs) can undergo osteogenic differentiation under induction conditions. Cyclic tensile stress (CTS) can stimulate stem cell osteogenic differentiation. The present study explored the mechanism of CTS in hPDLSC osteogenic differentiation. The hPDLSCs of the 4th passage were selected. hPDLSCs were subjected to CTS with deformation of 10% elongation at 0.5 Hz for 1, 4, 8, 12 and 24 h. ALP activity and staining, ARS staining and detection of expressions of osteogenesis-related genes (RUNX2, OPN, Sp7 and OCN) were used to assess hPDLSC osteogenic differentiation ability. microRNA (miR)-129-5p and BMP2 expression and p-Smad1/5 level were detected under CTS stimulation. The binding relationship between miR-129-5p and BMP2 was predicted and verified. The osteogenic differentiation ability of CTS-treated hPDLSCs was evaluated after intervention of miR-129-5p and BMP2. CTS induced hPDLSC osteogenic differentiation, as manifested by increased ALP activities, osteogenesis-related gene expressions and mineralized nodules, together with positive ALP staining. CTS inhibited miR-129-5p expression, and promoted BMP2 expression and p-Smad1/5 level in hPDLSCs. miR-129-5p targeted BMP2. Overexpressed miR-129-5p or silenced BMP2 prevented hPDLSC osteogenic differentiation ability. We demonstrated that CTS inhibited miR-129-5p expression, and then activated the BMP2/Smad pathway, thereby showing stimulative effects on hPDLSC osteogenic differentiation.

The Role of Noncoding RNAs in Osteogenic Differentiation of Human Periodontal Ligament Stem Cells

Chronic inflammatory diseases, including periodontitis, are the most common causes of bone tissue destruction. Periodontitis often leads to loss of connective tissue homeostasis and reduced alveolar bone levels. Human periodontal ligament stem cells (PDLSCs), a population of multipotent stem cells derived from periodontal ligament tissues, are considered as candidate cells for the regeneration of alveolar bone and periodontal tissues. Periodontitis impairs the osteogenic differentiation of human PDLSCs. Noncoding RNAs (ncRNAs), including long noncoding RNA (lncRNA), microRNA (miRNA), and circular RNA (circRNA), have been proposed as vital regulators influencing several differentiation processes including bone regeneration. Still, the molecular mechanisms of ncRNAs regulating osteogenic differentiation of human PDLSCs remain poorly understood. Exploring the influence of ncRNAs in the process of osteogenic differentiation of human PDLSCs may provide novel therapeutic strategies for tissue regeneration as the regeneration of the lost periodontium is the ultimate goal of periodontal therapy.

lncRNA SNHG1 attenuates osteogenic differentiation via the miR‑101/DKK1 axis in bone marrow mesenchymal stem cells

The imbalance induced by inhibition of bone mesenchymal stem cell (BMSC) osteogenic differentiation results in osteoporosis (OP); however, the underlying regulatory mechanism is not completely understood. Long non-coding RNAs (lncRNAs) serve crucial roles in osteogenic differentiation; therefore, investigating their regulatory role in the process of osteogenic differentiation may identify a promising therapeutic target for OP. The expression of small nucleolar RNA host gene 1 (SNHG1), Dickkopf 1 (DKK1), microRNA (miR)-101, RUNX family transcription factor 2 (RUNX2), osteopontin (OPN) and osteocalin (OCN) were detected via reverse transcription-quantitative PCR. The protein expression levels of DKK1, β-catenin, RUNX2, OPN, OCN, osterix and collagen type I α1 chain were analyzed by performing western blotting. The osteoblastic phenotype was assessed by conducting alkaline phosphatase activity detection and Alizarin Red staining. The interaction between SNHG1 and miR-101 was validated by bioinformatics and luciferase assays. The regulatory role of SNHG1 in BMSC osteogenic differentiation was assessed. SNHG1 expression was downregulated in a time-dependent manner during the process of osteogenic differentiation. SNHG1 overexpression inhibited osteogenic differentiation compared with the pcDNA group. The results indicated that SNHG1 and DKK1 directly interacted with miR-101. Moreover, SNHG1 regulated the Wnt/β-catenin signaling pathway to inhibit osteogenic differentiation via the miR-101/DKK1 axis. The present study indicated that lncRNA SNHG1 could attenuate BMSC osteogenic differentiation via the miR-101/DKK1 axis as a competitive endogenous RNA. Therefore, the present study furthered the current understanding of the potential mechanism underlying lncRNAs in in osteogenic differentiation.

Emerging role of long non-coding RNAs in the pathogenesis of periodontitis

Periodontitis is a bacteria-related chronic immune-associated condition that destructs bone and connective tissues around teeth. With a high incidence rate, it is regarded as a condition that impose substantial health burden. About half of the variance in the severity of periodontitis is attributed to genetic factors. Long non-coding RNAs (lncRNAs) have crucial roles in the development of several disorders such as periodontitis. A number of studies have reported dysregulation of lncRNAs such as UCA1, ANRIL, FGD5-AS1, NEAT1, FAS-AS1, Linc-RAM and NKILA in gingival tissues or blood samples of patients with periodontitis in comparison with healthy subjects. Moreover, several single nucleotide polymorphisms within lncRNAs have been associated with the susceptibility to this disorder. In the current review, we discuss the most recent articles about the role of lncRNAs in the pathogenesis of periodontitis.

Suppression of osteogenic differentiation and mitochondrial function change in human periodontal ligament stem cells by melatonin at physiological levels

N-Acetyl-5-methoxytryptamine (melatonin, MT) at pharmacological concentrations promotes the osteogenic differentiation of human bone marrow-derived mesenchymal stem cells; however, its role at physiological concentrations (1 pM–10 nM) remains unclear. We explored the effects of 1 pM–1 µM MT on the osteogenic differentiation of human periodontal ligament stem cells (hPDLSCs) and its underlying mitochondrial dynamics-mediated mechanisms. T he PDLSC phenotype was detected by flow cytometry and evaluated for three-line differentiation. Alkaline phosphatase activity assay and Alizarin red staining were used to evaluate osteogenic differentiation. Osteogenesis-related gene and protein expression levels were measured by quantitative reverse transcription -polymerase chain reaction and western blotting. Mitochondrial function assays were performed using reactive oxygen species, ATP and NAD⁺/NADH kits and molecular mechanisms of mitochondrial dynamics-related proteins were assessed by western blotting. Our results have shown that physiological MT concentrations induced differentiation of hPDLSCs and down-regulated osteopontin (OPN) and osteocalcin (OCN) expression levels, which were restored or even up-regulated by 1 µM MT (lowest pharmacological concentration). Compared to the osteogenic induction alone, this treatment decreased the intracellular ATP content, whereas the intracellular reactive oxygen species level and NAD+/NADH ratio were increased. Mitochondrial function- and dynamics-related protein expression levels were consistent with those of osteogenic genes following osteogenic induction and MT treatment of hPDLSCs at various physiological concentrations. Physiological MT concentrations inhibited the osteogenic differentiation of hPDLSCs and simultaneously altered mitochondrial function. These findings provide insights into the stem cell tissue engineering and functions of MT.