Long Noncoding RNA X-Inactive Specific Transcript (XIST) Promotes Osteogenic Differentiation of Periodontal Ligament Stem Cells by Sponging MicroRNA-214-3p

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.

N6-methyladenosine promotes osteogenic differentiation of PDLSCs from periodontitis patients

OBJECTIVES

This study aimed to investigate the mechanism of N6-methyladenosine (m6A) in the osteogenic differentiation of periodontal ligament stem cells (PDLSCs) from periodontitis patients.

METHODS

Differentially m6A-methylated lncRNA/mRNA profiles were detected by a m6A epitranscriptomic microarray. Bioinformatics analysis was performed by Gene Ontology and Kyoto Encyclopedia of Genes and Genomes pathway analysis. The transfection efficiency of the lentivirus was detected. The osteogenic activity of PDLSCs from periodontitis patients (PPDLSCs) was assessed.

RESULTS

The microarray results showed that 275 lncRNAs and 1292 mRNAs were significantly differentially methylated between PPDLSCs and PDLSCs from healthy people. Among those lncRNAs, lncRNA4114 (transcript_ID: ENST00000444114) showed both reduced m6A methylation levels and expression levels in PPDLSCs. Further bioinformatics analysis predicted that the differentially methylated mRNAs were mainly involved in cell interaction, stem cell pluripotency, and osteogenic differentiation signals. Then, overexpression of methyltransferase like 3 (METTL3) promoted the osteogenic differentiation of PPDLSCs, while knocking down METTL3 showed an inhibitory effect. Furthermore, METTL3 overexpression promotes the stability of lncRNA4114 to upregulate the expression level. Moreover, lncRNA4114 overexpression promoted the osteogenic differentiation of PPDLSCs.

CONCLUSION

METTL3 promotes the osteogenic differentiation of PPDLSCs by regulating the stability of lncRNA4114.

The exo-microRNA (miRNA) signaling pathways in pathogenesis and treatment of stroke diseases: Emphasize on mesenchymal stem cells (MSCs)

A major factor in long-term impairment is stroke. Patients with persistent stroke and severe functional disabilities have few therapy choices. Long noncoding RNAs (lncRNAs) may contribute to the regulation of the pathophysiologic processes of ischemic stroke as shown by altered expression of lncRNAs and microRNA (miRNAs) in blood samples of acute ischemic stroke patients. On the other hand, multipotent mesenchymal stem cells (MSCs) increase neurogenesis, and angiogenesis, dampen neuroinflammation, and boost brain plasticity to improve functional recovery in experimental stroke models. MSCs can be procured from various sources such as the bone marrow, adipose tissue, and peripheral blood. Under the proper circumstances, MSCs can differentiate into a variety of mature cells, including neurons, astrocytes, and oligodendrocytes. Accordingly, the capability of MSCs to exert neuroprotection and also neurogenesis has recently attracted more attention. Nowadays, lncRNAs and miRNAs derived from MSCs have opened new avenues to alleviate stroke symptoms. Accordingly, in this review article, we examined various studies concerning the lncRNAs and miRNAs' role in stroke pathogenesis and delivered an overview of the therapeutic role of MSC-derived miRNAs and lncRNAs in stroke conditions.

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.

Emerging Role of miRNAs in the Pathogenesis of Periodontitis

MicroRNAs (miRNAs) have been found to participate in the pathogenesis of several immune-related conditions through the modulation of the expression of cytokine coding genes and other molecules that affect the activity of the immune system. Periodontitis is an example of these conditions associated with the dysregulation of several miRNAs. Several miRNAs such as let-7 family, miR-125, miR-378, miR-543, miR-302, miR-214, miR-200, miR-146, miR-142, miR-30 and miR-21 have been shown to be dysregulated in patients with periodontitis. miR-146 is the most assessed miRNA in these patients, which is up-regulated in most studies in patients with periodontitis. In the present review, we describe the impact of miRNAs dysregulation on the pathoetiology of periodontitis.

Role of maternally expressed 8 small nucleolar RNA (MEG8) in osteogenic differentiation of periodontal ligament stem cells

OBJECTIVES

Periodontal ligament stem cells (PDLSCs) are essential for the treatment of bone diseases because of its great potential to differentiate into osteoblasts. Remarkably, increasing long-non-coding RNAs (lncRNAs) have been reported to be involved in the osteogenic differentiation of PDLSCs. Maternally expressed 8, small nucleolar RNA host gene (MEG8) is implicated in multiple diseases. This study intended to unearth the potential role of MEG8 and unveil the mechanism in PDLSCs undergoing osteoblastic differentiation.

MATERIALS AND METHODS

MEG8 expression was measured by quantitative real-time PCR (RT-qPCR) during osteogenic differentiation of PDLSCs into bone cells. Functional assays were used to uncover the biological function of MEG8. Besides, RNA pulldown, RNA-binding protein immunoprecipitation (RIP), and luciferase reporter assays were used to explore the molecular mechanism of MEG8.

RESULTS

MEG8 was apparently overexpressed in osteogenically differentiated PDLSCs. Moreover, MEG8 deficiency suppressed the osteoblastic differentiation of PDLSCs. Furthermore, MEG8 modulated the expression of transcription factor 4 (TCF4) by scavenging microRNA-495-3p (miR-495-3p) and microRNA-485-3p (miR-485-3p) through the competing endogenous RNA (ceRNA) mechanism, further stimulating the Wnt/β-catenin pathway.

CONCLUSION

MEG8 stimulates the capacity of PDLSCs for osteogenic differentiation through a ceRNA mode.

Long non-coding RNA X-Inactive Specific Transcript (XIST) interacting with USF2 promotes osteogenic differentiation of periodontal ligament stem cells through regulation of WDR72 transcription

BACKGROUND

Periodontal ligament stem cells (PDLSCs) are the most potential cells in periodontal tissue regeneration and bone tissue regeneration. Our prior work had revealed that WD repeat-containing protein 72 (WDR72) was crucial for osteogenic differentiation of PDLSCs. Here, we further elucidated its underlying mechanism in PDLSC osteogenic differentiation.

METHODS

Human PDLSCs, isolated and identified by flow cytometry, were prepared for osteogenic differentiation induction. Levels of WDR72, long non-coding RNA X-Inactive Specific Transcript (XIST), upstream stimulatory factor 2 (USF2), and osteogenic marker genes (Runx2, Osteocalcin, and Collagen I) in human PDLSCs and clinical specimens were detected by RT-qPCR. Protein expressions of WDR72, Runx2, Osteocalcin, and Colla1 were tested by Western blot. The interactions among the molecules were verified by RIP, RNA pull-down, ChIP, and luciferase reporter assays. Osteogenic differentiation was evaluated by alkaline phosphatase (ALP) and alizarin red staining (ARS).

RESULTS

WDR72 was decreased in periodontal tissues of periodontitis patients, and overexpression reversed TNF-α-mediated suppressive effects on PDLSC osteogenic differentiation. Mechanically, XIST recruited the enrichment of USF2 to the WDR72 promoter region, thereby positively regulating WDR72. WDR72 silencing overturned XIST-mediated biological effects in PDLSCs.

CONCLUSION

WDR72, regulated by the XIST/USF2 axis, enhances osteogenic differentiation of PDLSCs, implying a novel strategy for alleviating periodontitis.

DUXAP8 Promotes LPS-Induced Cell Injury in Pulpitis by Regulating miR-18b-5p/HIF3A

BACKGROUND

The dysregulated long noncoding RNAs (lncRNAs) are implicated in progression of various diseases, including pulpitis. Double homeobox A pseudogene 8 (DUXAP8) has been found to be upregulated in pulpitis. Herein, the functional mechanism of DUXAP8 in lipopolysaccharide (LPS)-induced pulpitis was explored.

MATERIAL AND METHODS

DUXAP8, microRNA-18b-5p (miR-18b-5p), or hypoxia-inducible factor 3A (HIF3A) levels were examined through reverse transcription-quantitative polymerase chain reaction assay. Cell behaviours were determined by Cell Counting Kit-8 assay for cell viability, Ethynyl-2'-deoxyuridine (EdU) assay for cell proliferation, and flow cytometry for cell apoptosis. Protein levels were measured using western blot. Inflammatory reaction was analysed via enzyme-linked immunosorbent assay. Oxidative stress was assessed by commercial kits. Dual-luciferase reporter assay, RNA immunoprecipitation assay, and pull-down assay were used for validation of interaction between targets.

RESULTS

Cell apoptosis, inflammatory reaction, and oxidative stress were induced by LPS in human dental pulp cells (HDPCs). DUXAP8 upregulation and miR-18b-5p downregulation were found in pulpitis. LPS-induced cell injury was relieved after downregulation of DUXAP8. DUXAP8 interacted with miR-18b-5p. The regulation of DUXAP8 was related to miR-18b-5p sponging function in LPS-treated HDPCs. HIF3A served as a target of miR-18b-5p. MiR-18b-5p protected against LPS-induced cell injury through targeting HIF3A. DUXAP8 targeted miR-18b-5p to regulate HIF3A level.

CONCLUSIONS

Results demonstrated that LPS-induced cell injury in pulpitis was promoted by DUXAP8 through mediating miR-18b-5p/HIF3A axis.

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.

LncRNA00638 promotes the osteogenic differentiation of periodontal mesenchymal stem cells from periodontitis patients under static mechanical strain

BACKGROUND

The osteogenic differentiation capacity of periodontal mesenchymal stem cells (PDLSCs) can be influenced by different levels of static mechanical strain (SMS) in an inflammatory microenvironment. Long non-coding RNAs (lncRNAs) are involved in various physiological processes. However, the mechanisms by which lncRNAs regulate the osteogenic differentiation of PDLSCs remain unclear.

METHODS

We investigated the responses of PDLSCs obtained from periodontitis patients and healthy people to 8% and 12%SMS. Gene microarray and bioinformatics analyses were implemented and identified lncRNA00638 as a target gene for the osteogenesis of PDLSCs from periodontitis patients under SMS. Competing endogenous RNA (ceRNA) network analysis was applied and predicted interactions among lncRNA00638, miRNA-424-5p, and fibroblast growth factor receptor 1 (FGFR1). Gene expression levels were regulated by lentiviral vectors. Cell Counting Kit-8 assays, alkaline phosphatase assays, and Alizarin Red S staining were used to examine the osteogenic potential. RT-qPCR and Western blot were performed to detect the expression levels of related genes and proteins.

RESULTS

We found that 8% and 12% SMS exerted distinct effects on HPDLSCs and PPDLSCs, with 12% SMS having the most significant effect. By microarray analysis, we detected differentially expressed lncRNAs/mRNAs between 12% SMS strained and static PPDLSCs, among which lncRNA00638 was detected as a positive target gene to promote the osteogenic differentiation of PPDLSCs under SMS loading. Mechanistically, lncRNA00638 may act as a ceRNA for miR-424-5p to compete with FGFR1. In this process, lncRNA00638 and miR-424-5p suppress each other and form a network to regulate FGFR1.

CONCLUSIONS

Our findings demonstrate that the lncRNA00638/miRNA-424-5p/FGFR1 regulatory network is actively involved in the regulation of PDLSC osteogenic differentiation from periodontitis patients under SMS loading, which may provide evidence for optimizing orthodontic treatments in patients with periodontitis.

Long non‑coding RNA SNHG5 promotes osteogenic differentiation of human periodontal ligament stem cells via mediating miR‑23b‑3p/Runx2 axis

The treatment of bone loss due to periodontitis has posed a great challenge for physicians for decades. Therefore, it is of extraordinary significance to identify an effective regeneration scheme for alveolar bone. This study aimed to investigate long non-coding RNA (lncRNA) small nucleolar RNA host gene 5 (SNHG5) whether sponges microRNA-23b-3p (miR-23b-3p) to achieve the osteogenic differentiation of human periodontal ligament stem cells (hPDLSCs). Results revealed that the expression of SNHG5 was upregulated whereas that of miR-23b-3p was downregulated in osteogenic hPDLSCs. Alizarin red staining assays and qRT-PCR demonstrated that SNHG5 silencing or miR-23b-3p overexpression inhibits hPDLSCs osteogenic differentiation and vice versa. In addition, miR-23b-3p partially abolished the promotive effect of SNHG5 on osteogenic differentiation of hPDLSCs. Dual luciferase report and RNA pulldown assay verified that miR-23b-3p is a regulatory target of SNHG5 and that Runx2 is a gene target of miR-23b-3p. In brief, the results demonstrate that SNHG5 promotes the osteogenic differentiation of hPDLSCs by regulating the miR-23b-3p/Runx2 axis. Our study provides novel mechanistic insights into the critical role of lncRNA SNHG5 as a miR-23b-3p sponge to regulate Runx2 expression in hPDLSCs and may serve as a potential therapeutics target for periodontitis.

Role of mechano-sensitive non-coding RNAs in bone remodeling of orthodontic tooth movement: recent advances

Orthodontic tooth movement relies on bone remodeling and periodontal tissue regeneration in response to the complicated mechanical cues on the compressive and tensive side. In general, mechanical stimulus regulates the expression of mechano-sensitive coding and non-coding genes, which in turn affects how cells are involved in bone remodeling. Growing numbers of non-coding RNAs, particularly mechano-sensitive non-coding RNA, have been verified to be essential for the regulation of osteogenesis and osteoclastogenesis and have revealed how they interact with signaling molecules to do so. This review summarizes recent findings of non-coding RNAs, including microRNAs and long non-coding RNAs, as crucial regulators of gene expression responding to mechanical stimulation, and outlines their roles in bone deposition and resorption. We focused on multiple mechano-sensitive miRNAs such as miR-21, - 29, -34, -103, -494-3p, -1246, -138-5p, -503-5p, and -3198 that play a critical role in osteogenesis function and bone resorption. The emerging roles of force-dependent regulation of lncRNAs in bone remodeling are also discussed extensively. We summarized mechano-sensitive lncRNA XIST, H19, and MALAT1 along with other lncRNAs involved in osteogenesis and osteoclastogenesis. Ultimately, we look forward to the prospects of the novel application of non-coding RNAs as potential therapeutics for tooth movement and periodontal tissue regeneration.

Fluid Shear Stress Promotes Osteoblast Proliferation and Suppresses Mitochondrial-Mediated Osteoblast Apoptosis Through the miR-214-3p-ATF4 Signaling Axis

MicroRNAs (miRNAs) play vital roles in bone metabolism and participate in the mechanically induced bone alterations. The underlying molecular mechanisms by which fluid shear stress (FSS) regulate the proliferative and apoptotic phenotypic changes of osteoblasts remain elusive. The study aimed to investigate the regulatory effects of FSS on osteoblast proliferative and apoptotic phenotypes and the roles of miR-214-3p-ATF4 (activating transcription factor 4) signaling axis in the mechanomodulation processes. FSS promoted the proliferative activity of osteoblasts and suppressed mitochondrial-mediated osteoblast apoptosis. FSS decreased miR-214-3p expression and increased ATF4 expression in MC3T3-E1 osteoblasts. MiR-214-3p inhibited osteoblast proliferative activity and promoted mitochondrial-mediated osteoblast apoptosis. Overexpression of miR-214-3p attenuated FSS-enhanced osteoblast proliferation and FSS-suppressed mitochondrial-mediated osteoblast apoptosis. We validated that ATF4 acted as a target gene of miR-214-3p. Moreover, miR-214 3p regulated osteoblast proliferation and apoptosis through targeting ATF4. Taken together, our study proved that FSS could suppress mitochondrial-mediated osteoblast apoptosis and promote osteoblast proliferation through the miR-214-3p-ATF4 signaling axis.

Identifying In Vitro Cultured Human Hepatocytes Markers with Machine Learning Methods Based on Single-Cell RNA-Seq Data

Cell transplantation is an effective method for compensating for the loss of liver function and improve patient survival. However, given that hepatocytes cultivated in vitro have diverse developmental processes and physiological features, obtaining hepatocytes that can properly function in vivo is difficult. In the present study, we present an advanced computational analysis on single-cell transcriptional profiling to resolve the heterogeneity of the hepatocyte differentiation process in vitro and to mine biomarkers at different periods of differentiation. We obtained a batch of compressed and effective classification features with the Boruta method and ranked them using the Max-Relevance and Min-Redundancy method. Some key genes were identified during the in vitro culture of hepatocytes, including CD147, which not only regulates terminally differentiated cells in the liver but also affects cell differentiation. PPIA, which encodes a CD147 ligand, also appeared in the identified gene list, and the combination of the two proteins mediated multiple biological pathways. Other genes, such as TMSB10, TMEM176B, and CD63, which are involved in the maturation and differentiation of hepatocytes and assist different hepatic cell types in performing their roles were also identified. Then, several classifiers were trained and evaluated to obtain optimal classifiers and optimal feature subsets, using three classification algorithms (random forest, k-nearest neighbor, and decision tree) and the incremental feature selection method. The best random forest classifier with a 0.940 Matthews correlation coefficient was constructed to distinguish different hepatic cell types. Finally, classification rules were created for quantitatively describing hepatic cell types. In summary, This study provided potential targets for cell transplantation associated liver disease treatment strategies by elucidating the process and mechanism of hepatocyte development at both qualitative and quantitative levels.

Progress in the Study of Non-Coding RNAs in Multidifferentiation Potential of Dental-Derived Mesenchymal Stem Cells

For decades, the desire for tissue regeneration has never been quenched. Dental-derived mesenchymal stem cells (DMSCs), with the potential of self-renewal and multi-directional differentiation, have attracted much attention in this topic. Growing evidence suggests that non-coding RNAs (ncRNAs) can activate various regulatory processes. Even with a slight decrease or increase in expression, ncRNAs can weaken or even subvert cellular fate. Therefore, a systematic interpretation of ncRNAs that guide the differentiation of DMSCs into cells of other tissue types is urgently needed. In this review, we introduce the roles of ncRNAs in the differentiation of DMSCs, such as osteogenic differentiation, odontogenic differentiation, neurogenic differentiation, angiogenic differentiation and myogenic differentiation. Additionally, we illustrate the regulatory mechanisms of ncRNAs in the differentiation of DMSCs, such as epigenetic regulation, transcriptional regulation, mRNA modulation, miRNA sponges and signalling. Finally, we summarize the types and mechanisms of ncRNAs in the differentiation of DMSCs, such as let-7 family, miR-17∼92 family, miR-21, lncRNA H19, lncRNA ANCR, lncRNA MEG3, circRNA CDR1as and CircRNA SIPA1L1. If revealing the intricate relationship between ncRNAs and pluripotency of DMSCs 1 day, the application of DMSCs in regenerative medicine and tissue engineering will be improved. Our work could be an important stepping stone towards this future.

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.

Autophagy-Related Genes Predict the Progression of Periodontitis Through the ceRNA Network

Purpose

The goal of this study was to identify the crucial autophagy-related genes (ARGs) in periodontitis and construct mRNA-miRNA-lncRNA networks to further understand the pathogenesis of periodontitis.

Methods

We used the Gene Expression Omnibus (GEO) database and Human Autophagy Database (HADb) to identify differentially expressed mRNAs, miRNAs, and ARGs. These ARGs were subjected to Gene Ontology (GO), KEGG (Kyoto Encyclopedia of Genes and Genomes) pathway, and PPI (protein–protein interaction) network analysis. Two databases (miRDB and StarBase v2.0) were used to reverse-predict miRNAs while the miRNA-lncRNA interaction was predicted using the StarBase v2.0 and LncBase Predicted v.2 databases. After excluding the lncRNAs only present in the nucleus, a competing endogenous RNA (ceRNA) network was built. Finally, we used quantitative real-time PCR (qRT-PCR) to confirm the levels of mRNA expression in the ceRNA network.

Results

The differential expression analysis revealed 10 upregulated and 10 downregulated differentially expressed ARGs. After intersecting the reverse-predicted miRNAs with the differentially expressed miRNAs, a ceRNA network consisting of 4 mRNAs (LAMP2, NFE2L2, NCKAP1, and EGFR), 3 miRNAs (hsa-miR-140-3p, hsa-miR-142-5p, and hsa-miR-671-5p), and 30 lncRNAs was constructed. In addition, qRT-PCR results revealed that EGFR expression was downregulated in diseased gingival tissue of periodontitis patients.

Conclusion

Four autophagy-related genes, especially EGFR, may play a key role in periodontitis progression. The novel ceRNA network may aid in elucidating the role and the mechanism of autophagy in periodontitis, which could be important in developing new therapeutic options.

Long noncoding RNA Lnc-DIF inhibits bone formation by sequestering miR-489-3p

Osteoporosis has become a high incident bone disease along with the aging of human population. Long noncoding RNAs (LncRNAs) play an important role in osteoporosis incidence. In this study, we screened out an LncRNA negatively correlated with osteoblast differentiation, which was therefore named Lnc-DIF (differentiation inhibiting factor). Functional analysis proved that Lnc-DIF inhibited bone formation. A special structure containing multiple 53 nucleotide repeats was found in the trailing end of Lnc-DIF. Our study suggested that this repeat sequence could sequester multiple miR-489-3p and inhibit bone formation through miR-489-3p/SMAD2 axis. Moreover, siRNA of Lnc-DIF would rescue bone formation in both aging and ovariectomized osteoporosis mice. This study revealed a kind of LncRNA that could function as a sponge and regulate multiple miRNAs. RNA therapy techniques that target these LncRNAs could manipulate its downstream miRNA-target pathway with significantly higher efficiency and specificity. This provided potential therapeutic insight for RNA-based therapy for osteoporosis.

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Identified LncRNA Lnc-DIF that inhibited bone formation

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Lnc-DIF sequestered multiple miR-489-3p by the repeat sequences on its trailing end

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Lnc-DIF repeat sequence inhibited bone formation via miR-489-3p/SMAD2 axis

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Lnc-DIF siRNA showed strong capability on rescuing osteoporosis

Human Sex Matters: Y-Linked Lysine Demethylase 5D Drives Accelerated Male Craniofacial Osteogenic Differentiation

Female sex is increasingly associated with a loss of bone mass during aging and an increased risk of developing nonunion fractures. Hormonal factors and cell-intrinsic mechanisms are suggested to drive these sexual dimorphisms, although underlying molecular mechanisms are still a matter of debate. Here, we observed a decreased capacity of calvarial bone recovery in female rats and a profound sexually dimorphic osteogenic differentiation in human adult neural crest-derived stem cells (NCSCs). Next to an elevated expression of pro-osteogenic regulators, global transcriptomics revealed Lysine Demethylase 5D (KDM5D) to be highly upregulated in differentiating male NCSCs. Loss of function by siRNA or pharmacological inhibition of KDM5D significantly reduced the osteogenic differentiation capacity of male NCSCs. In summary, we demonstrated craniofacial osteogenic differentiation to be sexually dimorphic with the expression of KDM5D as a prerequisite for accelerated male osteogenic differentiation, emphasizing the analysis of sex-specific differences as a crucial parameter for treating bone defects.

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.

Comprehensive analysis of the long noncoding RNA-associated competitive endogenous RNA network in the osteogenic differentiation of periodontal ligament stem cells

BACKGROUD

The mechanism implicated in the osteogenesis of human periodontal ligament stem cells (PDLSCs) has been investigated for years. Previous genomics data analyses showed that long noncoding RNA (lncRNA), microRNA (miRNA) and messenger RNA (mRNA) have significant expression differences between induced and control human PDLSCs. Competing for endogenous RNAs (ceRNA), as a widely studied mechanism in regenerative medicine, while rarely reported in periodontal regeneration. The key lncRNAs and their ceRNA network might provide new insights into molecular therapies of periodontal regeneration based on PDLSCs.

RESULTS

Two networks reflecting the relationships among differentially expressed RNAs were constructed. One ceRNA network was composed of 6 upregulated lncRNAs, 280 upregulated mRNAs, and 18 downregulated miRNAs. The other network contained 33 downregulated lncRNAs, 73 downregulated mRNAs, and 5 upregulated miRNAs. Functional analysis revealed that 38 GO terms and 8 pathways related with osteogenesis were enriched. Twenty-four osteogenesis-related gene-centred lncRNA-associated ceRNA networks were successfully constructed. Among these pathways, we highlighted MAPK and TGF-beta pathways that are closely related to osteogenesis. Subsequently, subnetworks potentially linking the GO:0001649 (osteoblast differentiation), MAPK and TGF-beta pathways were constructed. The qRT-PCR validation results were consistent with the microarray analysis.

CONCLUSION

We construct a comprehensively identified lncRNA-associated ceRNA network might be involved in the osteogenesis of PDLSCs, which could provide insights into the regulatory mechanisms and treatment targets of periodontal regeneration.

Expression of long noncoding RNA Xist is induced by glucocorticoids

Glucocorticoids (GCs) are potent anti-inflammatory and immunosuppressive agents. However, their clinical usage is limited by severe multisystemic side effects. Glucocorticoid induced osteoporosis results in significant morbidity and mortality but the cellular and molecular mechanisms underlying GC-induced bone loss are not clear. GC use results in decreased osteoblast differentiation with increased marrow adiposity through effects on bone marrow stem cells. GC effects are transduced through its receptor (GR). To identify novel GR regulated genes, we performed RNA sequencing (RNA-Seq) analysis comparing conditional GR knockout mouse made by crossing the floxed GR animal with the Col I promoter-Cre, versus normal floxed GR without Cre, and that testing was specific for Col I promoter active cells, such as bone marrow mesenchymal stem/osteoprogenitor cells (MSCs) and osteoblasts. Results showed 15 upregulated genes (3- to 10-fold) and 70 downregulated genes (-2.7- to -10-fold), with the long noncoding RNA X-inactive specific transcript (Xist) downregulated the most. The differential expression of genes measured by RNA-Seq was validated by qRT-PCR analysis of selected genes and the GC/GR signaling-dependent expression of Xist was further demonstrated by GC (dexamethasone) treatment of GR-deficient MSCs in vitro and by GC injection of C57BL/6 mice (wild-type males and females) in vivo. Our data revealed that the long noncoding RNA Xist is a GR regulated gene and its expression is induced by GC both in vitro and in vivo. To our knowledge, this is the first evidence showing that Xist is transcriptionally regulated by GC/GR signaling.

Long noncoding RNA XIST modulates microRNA-135/CREB1 axis to influence osteogenic differentiation of osteoblast-like cells in mice with tibial fracture healing

Fracture healing is a complex event with the involvement of many cell systems, cytokines, as well as mRNAs. Herein, we report the interactions among long noncoding RNA X-inactive specific transcript (XIST)/microRNA-135 (miR-135)/cAMP response element-binding protein 1 (CREB1) axis during fracture healing. We observed increased expression of XIST in patients with long-term unhealed fracture by microarray analysis. Subsequently, a mouse model with tibial fracture and a cell model using osteoblast-like MC3T3-E1 cells were generated. The XIST overexpression during fracture healing decreased proliferation and differentiation of MC3T3-E1 cells, while silencing of XIST facilitated MC3T3-E1 cell growth. Furthermore, miR-135 targeted CREB1 and negatively regulated its expression. XIST acted as a sponge for miR-135, thereby upregulating CREB1 and promoting the activity of the TNF-α/RANKL pathway. Transfection of miR-135 inhibitor or CREB1 overexpression blocked the stimulating effects of XIST knockdown on MC3T3-E1 cell growth. Besides, specific inhibitors of the TNF-α/RANKL pathway reversed the repressive role of XIST in cell osteogenic differentiation. All in all, these findings suggest that XIST knockdown induces the differentiation of osteoblast-like cells via regulation of the miR-135/CREB1/TNF-α/RANKL axis. XIST, as a consequence, represents an attractive therapeutic strategy to accelerate fracture healing.

The Role of Long Non-Coding RNAs and Circular RNAs in Bone Regeneration: Modulating MiRNAs Function

Although bone is a self-healing organ and is able to repair and restore most fractures, large bone fractures, about 10%, are not repairable. Bone grafting, as a gold standard, and bone tissue engineering using biomaterials, growth factors, and stem cells have been developed to restore large bone defects. Since bone regeneration is a complex and multiple-step process and the majority of the human genome, about 98%, is composed of the non-protein-coding regions, non-coding RNAs (ncRNAs) play essential roles in bone regeneration. Recent studies demonstrated that long ncRNAs (lncRNAs) and circular RNAs (circRNAs), as members of ncRNAs, are widely involved in bone regeneration by interaction with microRNAs (miRNAs) and constructing a lncRNA or circRNA/miRNA/mRNA regulatory network. The constructed network regulates the differentiation of stem cells into osteoblasts and their commitment to osteogenesis. This review will present the structure and biogenesis of lncRNAs and circRNAs, the mechanism of bone repair, and the bone tissue engineering in bone defects. Finally, we will discuss the role of lncRNAs and circRNAs in osteogenesis and bone fracture healing through constructing various lncRNA or circRNA/miRNA/mRNA networks and the involved pathways. This article is protected by copyright. All rights reserved.

MicroRNA-214 in Health and Disease

MicroRNAs (miRNAs) are endogenously expressed, non-coding RNA molecules that mediate the post-transcriptional repression and degradation of mRNAs by targeting their 3′ untranslated region (3′-UTR). Thousands of miRNAs have been identified since their first discovery in 1993, and miR-214 was first reported to promote apoptosis in HeLa cells. Presently, miR-214 is implicated in an extensive range of conditions such as cardiovascular diseases, cancers, bone formation and cell differentiation. MiR-214 has shown pleiotropic roles in contributing to the progression of diseases such as gastric and lung cancers but may also confer cardioprotection against excessive fibrosis and oxidative damage. These contrasting functions are achieved through the diverse cast of miR-214 targets. Through silencing or overexpressing miR-214, the detrimental effects can be attenuated, and the beneficial effects promoted in order to improve health outcomes. Therefore, discovering novel miR-214 targets and understanding how miR-214 is dysregulated in human diseases may eventually lead to miRNA-based therapies. MiR-214 has also shown promise as a diagnostic biomarker in identifying breast cancer and coronary artery disease. This review provides an up-to-date discussion of miR-214 literature by describing relevant roles in health and disease, areas of disagreement, and the future direction of the field.

LncRNA XIST shuttled by adipose tissue-derived mesenchymal stem cell-derived extracellular vesicles suppresses myocardial pyroptosis in atrial fibrillation by disrupting miR-214-3p-mediated Arl2 inhibition

The mechanisms underlying atrial fibrillation (AF), a type of heart arrhythmia, have not been fully identified. Long noncoding RNAs (lncRNAs) have been implicated in the progression of AF. The current study aimed to ascertain the means by which X-inactive specific transcript (XIST), a lncRNA, contributes to the pathogenesis of AF in an animal model or in atrial myocytes. Extracellular vesicles (EVs) derived from mouse adipose tissue-derived mesenchymal stem cells (AMSCs) were isolated, transfected with XIST, and either injected into AF mouse models or incubated with atrial myocytes. The in vitro and in vivo effects of EV-derived XIST on myocardial pyroptosis were determined by Western blot analysis of pyroptosis-related protein and an ELISA for inflammatory factors. Bioinformatics analysis revealed a relationship between XIST, microRNA (miR)-214-3p, and Arl2, which was subsequently verified by a dual luciferase assay and RNA immunoprecipitation. Functional experiments were performed to elucidate whether changes in miR-214-3p or Arl2 regulated the effect of XIST on myocardial pyroptosis. Overexpressed XIST from AMSC-EVs were found to decrease myocardial pyroptosis while alleviating inflammation, which was demonstrated by reduced expression of nucleotide-binding and oligomerization domain-like receptor family pyrin domain-containing 3 (NLRP3), apoptosis-associated speck-like protein containing a CARD (ASC), cleared-caspase-1/caspase-1 and gasdermin D (GSDMD), as well as the amount of interleukin (IL)-1β and IL-18 in both the cardiomyocytes and AF mouse tissues. Mechanistically, XIST is a competing endogenous RNA (ceRNA) of miR-214-3p, triggering upregulation of its target gene Arl2. Silencing of Arl2 or overexpression miR-214-3p reversed the effects of XIST on inflammation and pyroptosis. Taken together, the key findings of our study suggest that XIST may blunt myocardial pyroptosis by absorbing miR-214-3p to promote Arl2 expression, providing encouraging insight into XIST-based targeted therapy for AF.

Long non-cording RNA XIST promoted cell proliferation and suppressed apoptosis by miR-423-5p/HMGA2 axis in diabetic nephropathy

This research studied the effect of long non-coding RNA X-inactive-specific transcript (XIST) on DN. The effect of high glucose (HG) on the expression of XIST and miR-423-5p was detected by quantitative real-time PCR (qRT-PCR) in human kidney (HK) cells (human glomerular mesangial cells (HMCs) and human kidney-2 (HK-2) cells). The effect of XIST depletion and miR-423-5p inhibition or overexpression on high mobility group protein A2 (HMGA2) protein level was examined by western blot in HG-induced HK cells. The impacts of XIST depletion on viability and apoptosis were assessed by 3-(4, 5-dimethyl-2-thiazolyl)-2, 5-diphenyl-2-H-tetrazolium bromide (MTT) and flow cytometry assays in HG-induced HK cells. We found the expression of XIST and HMGA2 protein was significantly upregulated in DN tissues and cells. Moreover, HG treatment induced the upregulation of XIST and HMGA2 protein level in HK cells. Besides, both XIST depletion and HMGA2 depletion decreased cell proliferation but increased apoptosis in HG-treated HK cells. Furthermore, HMGA2 upregulation or miR-423-5p inhibition partly eliminated the effects of XIST depletion on cell proliferation, apoptosis of HG-treated HK cells. Interestingly, HMGA2 upregulation partly reversed miR-423-5p overexpression-mediated suppression on viability and promotion on apoptosis in HG-treated HK cells. Mechanistically, XIST sponged miR-423-5p to regulate HMGA2 expression in DN cells. Taken together, XIST depletion suppressed proliferation and promoted apoptosis via miR-423-5p/HMGA2 axis in HG-treated HK cells, which may provide a potential therapeutic target for DN.

LncRNA XIST restrains the activation of Müller cells and inflammation in diabetic retinopathy via stabilizing SIRT1

BACKGROUND

Recent studies have provided strong evidence that lncRNAs play a functional regulatory role in diabetic retinopathy (DR). The purpose of this study was to investigate the effect of long non-coding RNA (lncRNA) X-inactive specific transcript (XIST) in DR.

METHODS

A DR mouse model was established by intraperitoneal injection of streptozotocin (STZ), and then the mouse retinal Müller cells (mMCs) were isolated from retina tissues of mice. Human retinal Müller cell line (HMCs) and mMCs and were treated with high glucose (HG) to simulate an in vitro DR model. XIST expression was detected by qRT-PCR. Next, XIST overexpression was performed in mMCs and HMCs to examine its effect on the activation of Müller cells and production of pro-inflammatory cytokines. Subsequently, the interaction between XIST and SIRT1 was verified, and the ubiquitination level of SIRT1 as well as the stability of SIRT1 protein were assessed.

RESULTS

XIST was down-regulated in retinal tissues of DR mice and HG-induced HMCs. Overexpression of XIST inhibited HG-induced activation of mMCs and HMCs, and reduced the production of pro-inflammatory cytokines. XIST promoted SIRT1 expression via interacting with SIRT1 and inhibiting the ubiquitination of SIRT1. Furthermore, SIRT1 silencing partly abrogated the effect of XIST overexpression on the activation of mMCs and HMCs as well as the production of pro-inflammatory cytokines induced by HG.

CONCLUSION

We concluded that XIST restrained the activation of Müller cells and the production of pro-inflammatory cytokines via stabilizing SIRT1.

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.

Biological Function of Long Non-coding RNA (LncRNA) Xist

Long non-coding RNAs (lncRNAs) regulate gene expression in a variety of ways at epigenetic, chromatin remodeling, transcriptional, and translational levels. Accumulating evidence suggests that lncRNA X-inactive specific transcript (lncRNA Xist) serves as an important regulator of cell growth and development. Despites its original roles in X-chromosome dosage compensation, lncRNA Xist also participates in the development of tumor and other human diseases by functioning as a competing endogenous RNA (ceRNA). In this review, we comprehensively summarized recent progress in understanding the cellular functions of lncRNA Xist in mammalian cells and discussed current knowledge regarding the ceRNA network of lncRNA Xist in various diseases. Long non-coding RNAs (lncRNAs) are transcripts that are more than 200 nt in length and without an apparent protein-coding capacity (Furlan and Rougeulle, 2016; Maduro et al., 2016). These RNAs are believed to be transcribed by the approximately 98-99% non-coding regions of the human genome (Derrien et al., 2012; Fu, 2014; Montalbano et al., 2017; Slack and Chinnaiyan, 2019), as well as a large variety of genomic regions, such as exonic, tronic, and intergenic regions. Hence, lncRNAs are also divided into eight categories: Intergenic lncRNAs, Intronic lncRNAs, Enhancer lncRNAs, Promoter lncRNAs, Natural antisense/sense lncRNAs, Small nucleolar RNA-ended lncRNAs (sno-lncRNAs), Bidirectional lncRNAs, and non-poly(A) lncRNAs (Ma et al., 2013; Devaux et al., 2015; St Laurent et al., 2015; Chen, 2016; Quinn and Chang, 2016; Richard and Eichhorn, 2018; Connerty et al., 2020). A range of evidence has suggested that lncRNAs function as key regulators in crucial cellular functions, including proliferation, differentiation, apoptosis, migration, and invasion, by regulating the expression level of target genes via epigenomic, transcriptional, or post-transcriptional approaches (Cao et al., 2018). Moreover, lncRNAs detected in body fluids were also believed to serve as potential biomarkers for the diagnosis, prognosis, and monitoring of disease progression, and act as novel and potential drug targets for therapeutic exploitation in human disease (Jiang W. et al., 2018; Zhou et al., 2019a). Long non-coding RNA X-inactive specific transcript (lncRNA Xist) are a set of 15,000-20,000 nt sequences localized in the X chromosome inactivation center (XIC) of chromosome Xq13.2 (Brown et al., 1992; Debrand et al., 1998; Kay, 1998; Lee et al., 2013; da Rocha and Heard, 2017; Yang Z. et al., 2018; Brockdorff, 2019). Previous studies have indicated that lncRNA Xist regulate X chromosome inactivation (XCI), resulting in the inheritable silencing of one of the X-chromosomes during female cell development. Also, it serves a vital regulatory function in the whole spectrum of human disease (notably cancer) and can be used as a novel diagnostic and prognostic biomarker and as a potential therapeutic target for human disease in the clinic (Liu et al., 2018b; Deng et al., 2019; Dinescu et al., 2019; Mutzel and Schulz, 2020; Patrat et al., 2020; Wang et al., 2020a). In particular, lncRNA Xist have been demonstrated to be involved in the development of multiple types of tumors including brain tumor, Leukemia, lung cancer, breast cancer, and liver cancer, with the prominent examples outlined in Table 1. It was also believed that lncRNA Xist (Chaligne and Heard, 2014; Yang Z. et al., 2018) contributed to other diseases, such as pulmonary fibrosis, inflammation, neuropathic pain, cardiomyocyte hypertrophy, and osteoarthritis chondrocytes, and more specific details can be found in Table 2. This review summarizes the current knowledge on the regulatory mechanisms of lncRNA Xist on both chromosome dosage compensation and pathogenesis (especially cancer) processes, with a focus on the regulatory network of lncRNA Xist in human disease.

MicroRNAs: Harbingers and shapers of periodontal inflammation

Periodontal disease is an inflammatory reaction of the periodontal tissues to oral pathogens. In the present review we discuss the intricate effects of a regulatory network of gene expression modulators, microRNAs (miRNAs), as they affect periodontal morphology, function and gene expression during periodontal disease. These miRNAs are small RNAs involved in RNA silencing and post-transcriptional regulation and affect all stages of periodontal disease, from the earliest signs of gingivitis to the regulation of periodontal homeostasis and immunity and to the involvement in periodontal tissue destruction. MiRNAs coordinate periodontal disease progression not only directly but also through long non-coding RNAs (lncRNAs), which have been demonstrated to act as endogenous sponges or decoys that regulate the expression and function of miRNAs, and which in turn suppress the targeting of mRNAs involved in the inflammatory response, cell proliferation, migration and differentiation. While the integrity of miRNA function is essential for periodontal health and immunity, miRNA sequence variations (genetic polymorphisms) contribute toward an enhanced risk for periodontal disease progression and severity. Several polymorphisms in miRNA genes have been linked to an increased risk of periodontitis, and among those, miR-146a, miR-196, and miR-499 polymorphisms have been identified as risk factors for periodontal disease. The role of miRNAs in periodontal disease progression is not limited to the host tissues but also extends to the viruses that reside in periodontal lesions, such as herpesviruses (human herpesvirus, HHV). In advanced periodontal lesions, HHV infections result in the release of cytokines from periodontal tissues and impair antibacterial immune mechanisms that promote bacterial overgrowth. In turn, controlling the exacerbation of periodontal disease by minimizing the effect of periodontal HHV in periodontal lesions may provide novel avenues for therapeutic intervention. In summary, this review highlights multiple levels of miRNA-mediated control of periodontal disease progression, (i) through their role in periodontal inflammation and the dysregulation of homeostasis, (ii) as a regulatory target of lncRNAs, (iii) by contributing toward periodontal disease susceptibility through miRNA polymorphism, and (iv) as periodontal microflora modulators via viral miRNAs.

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.

Key Markers and Epigenetic Modifications of Dental-Derived Mesenchymal Stromal Cells

As a novel research hotspot in tissue regeneration, dental-derived mesenchymal stromal cells (MSCs) are famous for their accessibility, multipotent differentiation ability, and high proliferation. However, cellular heterogeneity is a major obstacle to the clinical application of dental-derived MSCs. Here, we reviewed the heterogeneity of dental-derived MSCs firstly and then discussed the key markers and epigenetic modifications related to the proliferation, differentiation, immunomodulation, and aging of dental-derived MSCs. These messages help to control the composition and function of dental-derived MSCs and thus accelerate the translation of cell therapy into clinical practice.

Long noncoding RNA AK039312 and AK079370 inhibits bone formation via miR-199b-5p

Osteoporosis caused by aging and menopause had become an emerging threat to human health. The reduction of osteoblast differentiation has been considered to be an essential cause of osteoporosis. Osteoblast differentiation could be regulated by LncRNAs, and increasing evidences have proved that LncRNAs may be adopted as potential therapeutic targets for osteoporosis. However, reports on rescue effects of LncRNAs in vivo are relatively limited. In this study, two LncRNAs (AK039312 and AK079370) were screened as osteogenic related LncRNAs. Both AK039312 and AK079370 could inhibit osteoblast differentiation and bone formation through suppressing osteogenic transcription factors. This inhibitory effect was achieved via binding and sequestering miR-199b-5p, and enhanced GSK-3β which further inhibited wnt/β-catenin pathway. Moreover, the siRNAs of AK039312 and AK079370 significantly alleviated postmenopausal osteoporosis, and the combination of si-AK039312 and si-AK079370 was more efficient than applying one si-LncRNA alone. This study has provided new insights for the therapy of osteoporosis.

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.