The histone acetyltransferase p300 regulates the expression of pluripotency factors and odontogenic differentiation of human dental pulp cells

Temporal and spatial distribution of histone acetylation in mouse molar development

Histone acetylation is one of the most widely studied histone modification, regulating a variety of biological activities like organ development and tumorigenesis. However, the role of histone acetylation in tooth development is poorly understood. Using the mouse molar as a model, we mapped the distribution patterns of histone H3 and H4, as well as their corresponding acetylation sites during tooth formation in order to unveil the connection between histone acetylation modification and tooth development. Moreover, key histone acetyltransferases and histone deacetylases were detected in both epithelial and mesenchymal cells during tooth development by scRNA-seq and immunohistochemistry. These results suggest that histone acetylation modification functions as an important mechanism in tooth development at different stages.

Epigenetic control of dental stem cells: progress and prospects in multidirectional differentiation

Dental stem cells, with their exceptional proliferative capacity and multidirectional differentiation potential, hold significant promise for dental and oral tissue regeneration. Epigenetic inheritance, which involves stable and heritable changes in gene expression and function without alterations to the DNA sequence, plays a critical role in numerous biological processes. Environmental factors are particularly influential in epigenetic inheritance, as variations in exposure can lead to changes in epigenetic modifications that subsequently impact gene expression. Epigenetic mechanisms are widely involved in processes such as bone homeostasis, embryogenesis, stem cell fate determination, and disease development. Recently, the epigenetic regulation of dental stem cells has attracted considerable research attention. This paper reviews studies focused on the epigenetic mechanisms governing the multidirectional differentiation of dental stem cells.

Can social adversity alter the epigenome, trigger oral disease, and affect future generations?

The nature versus nurture debate has intrigued scientific circles for decades. Although extensive research has established a clear relationship between genetics and disease development, recent evidence has highlighted the insufficiency of attributing adverse health outcomes to genetic factors alone. In fact, it has been suggested that environmental influences, such as socioeconomic position (SEP), may play a much larger role in the development of disease than previously thought, with extensive research suggesting that low SEP is associated with adverse health conditions. In relation to oral health, a higher prevalence of caries (tooth decay) exists among those of low SEP. Although little is known about the biological mechanisms underlying this relationship, epigenetic modifications resulting from environmental influences have been suggested to play an important role. This review explores the intersection of health inequalities and epigenetics, the role of early-life social adversity and its long-term epigenetic impacts, and how those living within the lower hierarchies of the socioeconomic pyramid are indeed at higher risk of developing diseases, particularly in relation to oral health. A deeper understanding of these mechanisms could lead to the development of targeted interventions for individuals of low SEP to improve oral health or identify those who are at higher risk of developing oral disease.

Histone-modifying enzymes: Roles in odontogenesis and beyond

OBJECTIVES

Odontogenesis, an intricate process initiated by epithelium-mesenchyme interaction, is meticulously regulated by a cascade of regulatory mechanisms. Epigenetic modifications, especially histone modification, have been found to exhibit spatiotemporal specificity during tooth development. However, the expression patterns and roles of enzymes associated with histone modifications have yet to be systematically explored in odontogenesis. This review aims to summarize the histone-modifying enzymes in odontogenesis and their regulation mechanism during tooth development and provide the potential theoretical basis for the clinical management and intervention of dental developmental diseases.

SUBJECTS AND METHODS

This study conducted a systematic search across PubMed and Web of Science databases, utilizing the keywords "odontogenesis," "histone modification," and "enzyme" for pertinent articles.

RESULTS

No doubt histone modification contributes extensively to odontogenesis regulation, and the disturbances in histone modifications can derange the odontogenesis process.

CONCLUSION

Further studies are warranted to elucidate these roles and their potential downstream effects, positioning histone modifications as a pivotal focal point for unraveling the intricacies of tooth development and regeneration.

Elucidating epigenetic mechanisms governing odontogenic differentiation in dental pulp stem cells: an in-depth exploration

Epigenetics refers to the mechanisms such as DNA methylation and histone modification that influence gene expression without altering the DNA sequence. These epigenetic modifications can regulate gene transcription, splicing, and stability, thereby impacting cell differentiation, development, and disease occurrence. The formation of dentin is intrinsically linked to the odontogenic differentiation of dental pulp stem cells (DPSCs), which are recognized as the optimal cell source for dentin-pulp regeneration due to their varied odontogenic potential, strong proliferative and angiogenic characteristics, and ready accessibility Numerous studies have demonstrated the critical role of epigenetic regulation in DPSCs differentiation into specific cell types. This review thus provides a comprehensive review of the mechanisms by which epigenetic regulation controls the odontogenesis fate of DPSCs.

Evaluation of the Effects of Opium on the Expression of SOX2 and OCT4 in Wistar Rat Bladder

BACKGROUND

Bladder cancer is a malignancy greatly affected by behavioral habits. The aim of this study was to examine the effect of opium on changes in the expression of OCT4 and SOX2 in the bladder tissue of rats.

METHOD

Thirty six rats were divided into six groups: 24 rats in the addicted group received morphine and opium for 4 months with 12 rats in the control group. Blood testing was done for the evaluation of CBC, MDA, and TAC. The bladder tissue was removed and checked by histopathological examination. All total RNA was extracted, then cDNAs were synthesized and the OCT4 and SOX2 gene expressions were evaluated by Real-time PCR.

RESULTS

The OCT4 mRNA expression level in the opium group of rats was significantly increased compared to the control group (13.5 and 6.8 fold in males and females respectively). Also, in the morphine group, similar augmentation was detected (3.8 and 6.7 fold in males and females respectively). The SOX2 mRNA over-expression level was seen in the morphine group of both genders as compared to the control group (3.7 and 4.2 fold in male and female respectively) but in the opium group, enhancement of mRNA level was seen only in males (6.6 fold). Opium increases both OCT4 and SOX2 expression more than morphine in male rats, but in female rats, SOX2 is increased more by morphine.

CONCLUSION

Over expression of OCT4 and SOX2 was observed in rats treated with opium and morphine. Increased OCT4 and SOX2 expression was seen in opium-treated male rats, but in female rats, SOX2 was increased more by morphine.

Research progress in cell therapy for oral diseases: focus on cell sources and strategies to optimize cell function

In recent years, cell therapy has come to play an important therapeutic role in oral diseases. This paper reviews the active role of mesenchymal stem cells, immune cell sources, and other cells in oral disorders, and presents data supporting the role of cell therapy in oral disorders, including bone and tooth regeneration, oral mucosal disorders, oral soft tissue defects, salivary gland dysfunction, and orthodontic tooth movement. The paper will first review the progress of cell optimization strategies for oral diseases, including the use of hormones in combination with stem cells, gene-modified regulatory cells, epigenetic regulation of cells, drug regulation of cells, cell sheets/aggregates, cell-binding scaffold materials and hydrogels, nanotechnology, and 3D bioprinting of cells. In summary, we will focus on the therapeutic exploration of these different cell sources in oral diseases and the active application of the latest cell optimization strategies.

MicroRNA-93-5p regulates odontogenic differentiation and dentin formation via KDM6B

BACKGROUND

Epigenetic factors influence the odontogenic differentiation of dental pulp stem cells and play indispensable roles during tooth development. Some microRNAs can epigenetically regulate other epigenetic factors like DNA methyltransferases and histone modification enzymes, functioning as epigenetic-microRNAs. In our previous study, microarray analysis suggested microRNA-93-5p (miR-93-5p) was differentially expressed during the bell stage in human tooth germ. Prediction tools indicated that miR-93-5p may target lysine-specific demethylase 6B (KDM6B). Therefore, we explored the role of miR-93-5p as an epi-miRNA in tooth development and further investigated the underlying mechanisms of miR-93-5p in regulating odontogenic differentiation and dentin formation.

METHODS

The expression pattern of miR-93-5p and KDM6B of dental pulp stem cells (DPSCs) was examined during tooth development and odontogenic differentiation. Dual luciferase reporter and ChIP-qPCR assay were used to validate the target and downstream regulatory genes of miR-93-5p in human DPSCs (hDPSCs). Histological analyses and qPCR assays were conducted for investigating the effects of miR-93-5p mimic and inhibitor on odontogenic differentiation of hDPSCs. A pulpotomy rat model was further established, microCT and histological analyses were performed to explore the effects of KDM6B-overexpression and miR-93-5p inhibition on the formation of tertiary dentin.

RESULTS

The expression level of miR-93-5p decreased as odontoblast differentiated, in parallel with elevated expression of histone demethylase KDM6B. In hDPSCs, miR-93-5p overexpression inhibited the odontogenic differentiation and vice versa. MiR-93-5p targeted 3' untranslated region (UTR) of KDM6B, thereby inhibiting its protein translation. Furthermore, KDM6B bound the promoter region of BMP2 to demethylate H3K27me3 marks and thus upregulated BMP2 transcription. In the rat pulpotomy model, KDM6B-overexpression or miR-93-5p inhibition suppressed H3K27me3 level in DPSCs and consequently promoted the formation of tertiary dentin.

CONCLUSIONS

MiR-93-5p targets epigenetic regulator KDM6B and regulates H3K27me3 marks on BMP2 promoters, thus modulating the odontogenic differentiation of DPSCs and dentin formation.

The odontoblastic differentiation of dental mesenchymal stem cells: molecular regulation mechanism and related genetic syndromes

Dental mesenchymal stem cells (DMSCs) are multipotent progenitor cells that can differentiate into multiple lineages including odontoblasts, osteoblasts, chondrocytes, neural cells, myocytes, cardiomyocytes, adipocytes, endothelial cells, melanocytes, and hepatocytes. Odontoblastic differentiation of DMSCs is pivotal in dentinogenesis, a delicate and dynamic process regulated at the molecular level by signaling pathways, transcription factors, and posttranscriptional and epigenetic regulation. Mutations or dysregulation of related genes may contribute to genetic diseases with dentin defects caused by impaired odontoblastic differentiation, including tricho-dento-osseous (TDO) syndrome, X-linked hypophosphatemic rickets (XLH), Raine syndrome (RS), hypophosphatasia (HPP), Schimke immuno-osseous dysplasia (SIOD), and Elsahy-Waters syndrome (EWS). Herein, recent progress in the molecular regulation of the odontoblastic differentiation of DMSCs is summarized. In addition, genetic syndromes associated with disorders of odontoblastic differentiation of DMSCs are discussed. An improved understanding of the molecular regulation and related genetic syndromes may help clinicians better understand the etiology and pathogenesis of dentin lesions in systematic diseases and identify novel treatment targets.

The Role of Histone Acetylation Modification in Dental Tissue-Derived Mesenchymal Stem Cells and Odontogenesis

Odontogenesis is a complex physiological process that is based on dental tissue-derived mesenchymal stem cells (MSCs). Dental tissue-derived MSCs are the stem cell populations isolated and characterized from different parts of the oral cavity, and are considered as promising candidates for stem cell-based therapy. During odontogenesis, epigenetic factors can influence the proliferation, differentiation, or apoptosis of dental tissue-derived MSCs. As one of the epigenetic modifications, histone acetylation modification is critical for the proper regulation of many biological processes, including transcriptional regulation of cell cycle progression and cell fate. In odontogenesis, histone acetylation and deacetylation play crucial roles in odontogenic differentiation of dental tissue-derived MSCs. In this review, we aim to outline the general features of acetylation modification and describe their roles in odontogenic differentiation of dental tissue-derived MSCs, as well as their future implications in the field of novel regenerative therapies for the dentine-pulp complex.

Analysis of regulatory sequences in exosomal DNA of NANOGP8

Exosomes participate in intercellular communication by transporting functionally active molecules. Such cargo from the original cells comprising proteins, micro-RNA, mRNA, single-stranded (ssDNA) and double-stranded DNA (dsDNA) molecules pleiotropically transforms the target cells. Although cancer cells secrete exosomes carrying a significant level of DNA capable of modulating oncogene expression in a recipient cell, the regulatory mechanism is unknown. We have previously reported that cancer cells produce exosomes containing NANOGP8 DNA. NANOGP8 is an oncogenic paralog of embryonic stem cell transcription factor NANOG and does not express in cells since it is a pseudogene. However, in this study, we evaluated NANOGP8 expression in glioblastoma multiforme (GBM) tissue from a surgically removed brain tumor of a patient. Significantly higher NANOGP8 transcription was observed in GBM cancer stem cells (CSCs) than in GBM cancer cells or neural stem cells (NSCs), despite identical sequences of NANOGP8-upstream genomic region in all the cell lines. This finding suggests that upstream genomic sequences of NANOGP8 may have environment-dependent promoter activity. We also found that the regulatory sequences upstream of exosomal NANOGP8 GBM DNA contain multiple core promoter elements, transcription factor binding sites, and segments of human viruses known for their oncogenic role. The exosomal sequence of NANOGP8-upstream GBM DNA is different from corresponding genomic sequences in CSCs, cancer cells, and NSCs as well as from the sequences reported by NCBI. These sequence dissimilarities suggest that exosomal NANOGP8 GBM DNA may not be a part of the genomic DNA. Exosomes possibly acquire this DNA from other sources where it is synthesized by an unknown mechanism. The significance of exosome-bestowed regulatory elements in the transcription of promoter-less retrogene such as NANOGP8 remains to be determined.

DNA Methylation and Histone Modification in Dental-derived Mesenchymal Stem Cells

Epigenetic regulation, mainly involving DNA methylation, histone modification, and noncoding RNAs (ncRNAs), is essential for the regulation of multiple cellular processes. Dental-derived mesenchymal stem cells (DMSCs), a kind of multipotent cells derived from dental tissues, are impactful in regenerative medicine. Recent studies have shown that epigenetic regulation plays a major role in DMSCs. Therefore, exploring how epigenetic regulation is involved in DMSCs may be of guiding significance for tissue repair and regeneration or for exploring more effective treatments. A number of research of ncRNAs in DMSCs have been reported. However, little is known about the roles of DNA methylation and histone modifications in DMSCs. In this review, we summarize the important roles of DNA methylation and histone modifications of the fate of DMSCs.

CancerOmicsNet: a multi-omics network-based approach to anti-cancer drug profiling

Development of novel anti-cancer treatments requires not only a comprehensive knowledge of cancer processes and drug mechanisms of action, but also the ability to accurately predict the response of various cancer cell lines to therapeutics. Numerous computational methods have been developed to address this issue, including algorithms employing supervised machine learning. Nonetheless, high prediction accuracies reported for many of these techniques may result from a significant overlap among training, validation, and testing sets, making existing predictors inapplicable to new data. To address these issues, we developed CancerOmicsNet, a graph neural network with sophisticated attention propagation mechanisms to predict the therapeutic effects of kinase inhibitors across various tumors. Emphasizing on the system-level complexity of cancer, CancerOmicsNet integrates multiple heterogeneous data, such as biological networks, genomics, inhibitor profiling, and gene-disease associations, into a unified graph structure. The performance of CancerOmicsNet, properly cross-validated at the tissue level, is 0.83 in terms of the area under the receiver operating characteristics, which is notably higher than those measured for other approaches. CancerOmicsNet generalizes well to unseen data, i.e., it can predict therapeutic effects across a variety of cancer cell lines and inhibitors. CancerOmicsNet is freely available to the academic community at https://github.com/pulimeng/CancerOmicsNet.

Epigenetic regulation of dental pulp stem cells and its potential in regenerative endodontics

Regenerative endodontics (RE) therapy means physiologically replacing damaged pulp tissue and regaining functional dentin–pulp complex. Current clinical RE procedures recruit endogenous stem cells from the apical papilla, periodontal tissue, bone marrow and peripheral blood, with or without application of scaffolds and growth factors in the root canal space, resulting in cementum-like and bone-like tissue formation. Without the involvement of dental pulp stem cells (DPSCs), it is unlikely that functional pulp regeneration can be achieved, even though acceptable repair can be acquired. DPSCs, due to their specific odontogenic potential, high proliferation, neurovascular property, and easy accessibility, are considered as the most eligible cell source for dentin–pulp regeneration. The regenerative potential of DPSCs has been demonstrated by recent clinical progress. DPSC transplantation following pulpectomy has successfully reconstructed neurovascularized pulp that simulates the physiological structure of natural pulp. The self-renewal, proliferation, and odontogenic differentiation of DPSCs are under the control of a cascade of transcription factors. Over recent decades, epigenetic modulations implicating histone modifications, DNA methylation, and noncoding (nc)RNAs have manifested as a new layer of gene regulation. These modulations exhibit a profound effect on the cellular activities of DPSCs. In this review, we offer an overview about epigenetic regulation of the fate of DPSCs; in particular, on the proliferation, odontogenic differentiation, angiogenesis, and neurogenesis. We emphasize recent discoveries of epigenetic molecules that can alter DPSC status and promote pulp regeneration through manipulation over epigenetic profiles.

Effect of histone demethylase KDM5A on the odontogenic differentiation of human dental pulp cells

Human dental pulp cells (hDPCs) possess the capacity to differentiate into odontoblast-like cells in response to exogenous stimuli. Histone methylation is one of the most robust epigenetic marks and is essential for the regulation of multiple cellular processes. Previous studies have shown that histone methyltransferases (HMTs) and histone demethylases (HDMs) are crucial for the osteogenic differentiation of human bone marrow, adipose tissue, and tooth tissue. However, little is known about the role of histone methylation in hDPC differentiation. Here, the expression levels of HMTs and HDMs were profiled in hDPCs undergoing odontogenic induction. Among several differentially expressed enzymes, HDM KDM5A demonstrated significantly enhanced expression during cytodifferentiation. Furthermore, KDM5A expression increased during early passages and in a time-dependent manner during odontogenic induction. Using a shRNA-expressing lentivirus, KDM5A was knocked down in hDPCs. KDM5A depletion resulted in greater alkaline phosphatase activity and more mineral deposition formation. Meanwhile, the expression levels of the odontogenic markers DMP1, DSPP, OSX, and OCN were increased by KDM5A knockdown. As a histone demethylase specific for tri- and dimethylated histone H3 at lysine 4 (H3K4me3/me2), KDM5A deficiency led to a significant increment in total H3K4me3 levels, whereas no significant difference was found for H3K4 me2. H3K4me3 levels on the promoters of the odontogenic markers increased after KDM5A knockdown in hDPCs. These results demonstrated that KDM5A is present in hDPCs and inhibits the odontogenic differentiation potentiality of hDPCs by removing H3K4me3 from specific gene promoters, suggesting that KDM5A-dependent histone demethylation may play an important role in reparative dentinogenesis.

Epigenetic Regulation of Dental Pulp Stem Cell Fate

Epigenetic regulation, mainly involving DNA methylation, histone modification, and noncoding RNAs, affects gene expression without modifying the primary DNA sequence and modulates cell fate. Mesenchymal stem cells derived from dental pulp, also called dental pulp stem cells (DPSCs), exhibit multipotent differentiation capacity and can promote various biological processes, including odontogenesis, osteogenesis, angiogenesis, myogenesis, and chondrogenesis. Over the past decades, increased attention has been attracted by the use of DPSCs in the field of regenerative medicine. According to a series of studies, epigenetic regulation is essential for DPSCs to differentiate into specialized cells. In this review, we summarize the mechanisms involved in the epigenetic regulation of the fate of DPSCs.

The Long Non-coding RNA lnc-DMP1 Regulates Dmp1 Expression Through H3K27Ac Modification

Several long non-coding RNAs (lncRNAs) have been reported regulate the expression of neighbor protein-coding genes at post-transcriptional, transcriptional and epigenetic levels. Dmp1 (Dentin matrix protein 1), encoding a non-collagenous extracellular matrix protein, plays an important role in dentin and bone mineralization. However, the transcriptional regulation of lncRNA on Dmp1 has not been reported. In this study, we identified a novel lncRNA named lnc-DMP1, which is near the Dmp1 gene region and undergoes remarkable changes during mandible development. lnc-DMP1 is co-localized and significantly expressed correlation with Dmp1 in embryonic and postnatal mouse mandibles. In MC3T3-E1 cells, lnc-DMP1 positively regulates DMP1 expression and skeletal mineralization. Furthermore, lnc-DMP1 induces the promoter activity of Dmp1 by modulating H3K27Ac enrichment in the Dmp1 promoter. In conclusion, our results indicate that lnc-DMP1 is a novel lncRNA near the Dmp1 gene region and regulates Dmp1 expression by modulating the H3K27 acetylation level of Dmp1 promoter.

Wnt-3a Induces Epigenetic Remodeling in Human Dental Pulp Stem Cells

Dental pulp stem cells (DPSCs) from adult teeth show the expression of a very complete repertoire of stem pluripotency core factors and a high plasticity for cell reprogramming. Canonical Wnt and Notch signaling pathways regulate stemness and the expression of pluripotency core factors in DPSCs, and even very short-term (48 h) activations of the Wnt pathway induce a profound remodeling of DPSCs at the physiologic and metabolic levels. In this work, DPSC cultures were exposed to treatments modulating Notch and Wnt signaling, and also induced to differentiate to osteo/adipocytes. DNA methylation, histone acetylation, histone methylation, and core factor expression levels where assessed by mass spectroscopy, Western blot, and qPCR. A short-term activation of Wnt signaling by WNT-3A induced a genomic DNA demethylation, and increased histone acetylation and histone methylation in DPSCs. The efficiency of cell reprogramming methods relies on the ability to surpass the epigenetic barrier, which determines cell lineage specificity. This study brings important information about the regulation of the epigenetic barrier by Wnt signaling in DPSCs, which could contribute to the development of safer and less aggressive reprogramming methodologies with a view to cell therapy.

Coordinated expression of p300 and HDAC3 upregulates histone acetylation during dentinogenesis

Cellular differentiation is caused by highly controlled modifications in the gene expression but rarely involves a change in the DNA sequence itself. Histone acetylation is a major epigenetic factor that adds an acetyl group to histone proteins, thus altering their interaction with DNA and nuclear proteins. Illumination of the histone acetylation during dentinogenesis is important for odontoblast differentiation and dentinogenesis. In the current study, we aimed to discover the roles and regulation of acetylation at histone 3 lysine 9 (H3K9ac) and H3K27ac during dentinogenesis. We first found that both of these modifications were enhanced during odontoblast differentiation and dentinogenesis. These modifications are dynamically catalyzed by histone acetyltransferases (HATs) and deacetylases (HDACs), among which HDAC3 was decreased while p300 increased during odontoblast differentiation. Moreover, overexpression of HDAC3 or knockdown p300 inhibited odontoblast differentiation in vitro, and inhibition of HDAC3 and p300 with trichostatin A or C646 regulated odontoblast differentiation. Taken together, the results of our present study suggest that histone acetylation is involved in dentinogenesis and coordinated expression of p300- and HDAC3-regulated odontoblast differentiation through upregulating histone acetylation.

Emerging Role of Histone Acetyltransferase in Stem Cells and Cancer

Protein acetylation is one of the most important posttranslational modifications catalyzed by acetyltransferases and deacetylases, through the addition and removal of acetyl groups to lysine residues. Lysine acetylation can affect protein-nucleic acid or protein-protein interactions and protein localization, transport, stability, and activity. It regulates the function of a large variety of proteins, including histones, oncoproteins, tumor suppressors, and transcription factors, thus representing a crucial regulator of several biological processes with particular prominent roles in transcription and metabolism. Thus, it is unsurprising that alteration of protein acetylation is involved in human disease, including metabolic disorders and cancers. In this context, different hematological and solid tumors are characterized by deregulation of the protein acetylation pattern as a result of genetic or epigenetic changes. The imbalance between acetylation and deacetylation of histone or nonhistone proteins is also involved in the modulation of the self-renewal and differentiation ability of stem cells, including cancer stem cells. Here, we summarize a combination of in vitro and in vivo studies, undertaken on a set of acetyltransferases, and discuss the physiological and pathological roles of this class of enzymes. We also review the available data on the involvement of acetyltransferases in the regulation of stem cell renewal and differentiation in both normal and cancer cell population.

Teeth-derived stem cells: A source for cell therapy

Cell therapy is one of the important therapeutic approaches in the treatment of many diseases such as cancer, degenerative diseases, and cardiovascular diseases. Among various cell types, which could be used as cell therapies, stem cell therapy has emerged as powerful tools in the treatment of several diseases. Multipotent stem cells are one of the main classes of stem cells that could originate from different parts of the body such as bone marrow, adipose, placenta, and tooth. Among several types of multipotent stem cells, tooth-derived stem cells (TDSCs) are associated with special properties such as accessible, easy isolation, and low invasive, which have introduced them as a good source for using in the treatment of several diseases such as neural injuries, liver fibrosis, and Cohrn's disease. Here, we provided an overview of TDSCs particular stem cells from human exfoliated deciduous teeth and clinical application of them. Moreover, we highlighted molecular mechanisms involved in the regulation of dental stem cells fate.

Stem Cells from Dental Pulp: What Epigenetics Can Do with Your Tooth

Adult stem cells have attracted scientific attention because they are able to self-renew and differentiate into several specialized cell types. In this context, human dental tissue-derived mesenchymal stem cells (hDT-MSCs) have emerged as a possible solution for repairing or regenerating damaged tissues. These cells can be isolated from primary teeth that are naturally replaced, third molars, or other dental tissues and exhibit self-renewal, a high proliferative rate and a great multilineage potential. However, the cellular and molecular mechanisms that determine lineage specification are still largely unknown. It is known that a change in cell fate requires the deletion of existing transcriptional programs, followed by the establishment of a new developmental program to give rise to a new cell lineage. Increasing evidence indicates that chromatin structure conformation can influence cell fate. In this way, reversible chemical modifications at the DNA or histone level, and combinations thereof can activate or inactivate cell-type-specific gene sequences, giving rise to an alternative cell fates. On the other hand, miRNAs are starting to emerge as a possible player in establishing particular somatic lineages. In this review, we discuss two new and promising research fields in medicine and biology, epigenetics and stem cells, by summarizing the properties of hDT-MSCs and highlighting the recent findings on epigenetic contributions to the regulation of cellular differentiation.

HDAC inhibitor LMK‑235 promotes the odontoblast differentiation of dental pulp cells

The role of dental pulp cells (DPCs) in hard dental tissue regeneration had received increasing attention because DPCs can differentiate into odontoblasts and other tissue‑specific cells. In recent years, epigenetic modifications had been identified to serve an important role in cell differentiation, and histone deacetylase (HDAC) inhibitors have been widely studied by many researchers. However, the effects of HDAC4 and HDAC5 on the differentiation of DPCs and the precise molecular mechanisms remain unclear. The present study demonstrated that LMK‑235, a specific human HDAC4 and HDAC5 inhibitor, increased the expression of specific odontoblastic gene expression levels detected by reverse transcription‑quantitative polymerase chain reaction (RT‑qPCR) in dental pulp cells, and did not reduce cell proliferation tested by MTT assay after 3 days in culture at a low concentration. In addition, the mRNA and protein expression levels of dentin sialophosphoprotein, runt‑related transcription factor 2, alkaline phosphatase (ALP) and osteocalcin were evaluated by RT‑qPCR and western blotting, respectively. The increased gene and protein expression of specific markers demonstrated, indicating that LMK‑235 promoted the odontoblast induction of DPCs. ALP activity and mineralised nodule formation were also enhanced due to the effect of LMK‑235, detected by an ALP activity test and Alizarin Red S staining, respectively. Additionally, the vascular endothelial growth factor (VEGF)/RAC‑gamma serine/threonine‑protein kinase (AKT)/mechanistic target of rapamycin (mTOR) signalling pathway was tested to see if it takes part in the differentiation of DPCs treated with LMK‑235, and it was demonstrated that the mRNA expression levels of VEGF, AKT and mTOR were upregulated. These findings indicated that LMK‑235 may serve a key role in the proliferation and odontoblast differentiation of DPCs, and could be used to accelerate dental tissue regeneration.

Morphine delays neural stem cells differentiation by facilitating Nestin overexpression

BACKGROUND

Morphine is used as an analgesic although it causes important secondary effects. These effects are triggered by several mechanisms leading to the dysregulation of gene expression. Here we aimed to study these alterations on neural stem cells (NSC) during CNS development.

METHODS

AB strain and tg nestin:GFP zebrafish embryos, zebrafish primary neuron culture and mouse embryonic stem cells were used to assess the effect of morphine by qPCR, time lapse microscopy and western blot. ChIP-qPCR and bisulfite conversion assay were performed to determine the changes exerted by morphine in a Nestin candidate enhancer.

RESULTS

Morphine increases GFP in nestin:GFP embryos and overexpresses the NSC marker Nestin. Morphine also exerts a hyperacetylation effect on H3K27 and decreases DNA methylation within a region located 18 Kb upstream nestin transcription starting site. Here, a binding site for the transcription factor complex Sox2/Oct4/Nanog was predicted. These factors are also upregulated by morphine. Besides, morphine increases the histone acetyl transferase p300. The inhibition of p300 activity decreases Nestin.

CONCLUSIONS

Morphine facilitates Nestin increase by several mechanisms which include hyperacetylation of H3K27, decreased DNA methylation and the overexpression of the transcription factors sox2, oct4 and nanog. It has also been demonstrated that nestin levels depend on p300 activity. The facilitated Nestin expression delays the normal differentiation of neural stem cells.

GENERAL SIGNIFICANCE

The present work provides novel evidence of the effects induced by morphine in the normal differentiation of NSCs, altering Nestin through changes on p300, H3K27ac, DNA methylation and Oct4, Sox2, and Nanog.

Deciphering the Epigenetic Code in Embryonic and Dental Pulp Stem Cells

A close cooperation between chromatin states, transcriptional modulation, and epigenetic modifications is required for establishing appropriate regulatory circuits underlying self-renewal and differentiation of adult and embryonic stem cells. A growing body of research has established that the epigenome topology provides a structural framework for engaging genes in the non-random chromosomal interactions to orchestrate complex processes such as cell-matrix interactions, cell adhesion and cell migration during lineage commitment. Over the past few years, the functional dissection of the epigenetic landscape has become increasingly important for understanding gene expression dynamics in stem cells naturally found in most tissues. Adult stem cells of the human dental pulp hold great promise for tissue engineering, particularly in the skeletal and tooth regenerative medicine. It is therefore likely that progress towards pulp regeneration will have a substantial impact on the clinical research. This review summarizes the current state of knowledge regarding epigenetic cues that have evolved to regulate the pluripotent differentiation potential of embryonic stem cells and the lineage determination of developing dental pulp progenitors.

SMAR1 binds to T(C/G) repeat and inhibits tumor progression by regulating miR-371-373 cluster

Chromatin architecture and dynamics are regulated by various histone and non-histone proteins. The matrix attachment region binding proteins (MARBPs) play a central role in chromatin organization and function through numerous regulatory proteins. In the present study, we demonstrate that nuclear matrix protein SMAR1 orchestrates global gene regulation as determined by massively parallel ChIP-sequencing. The study revealed that SMAR1 binds to T(C/G) repeat and targets genes involved in diverse biological pathways. We observe that SMAR1 binds and targets distinctly different genes based on the availability of p53. Our data suggest that SMAR1 binds and regulates one of the imperative microRNA clusters in cancer and metastasis, miR-371-373. It negatively regulates miR-371-373 transcription as confirmed by SMAR1 overexpression and knockdown studies. Further, deletion studies indicate that a ~200 bp region in the miR-371-373 promoter is necessary for SMAR1 binding and transcriptional repression. Recruitment of HDAC1/mSin3A complex by SMAR1, concomitant with alteration of histone marks results in downregulation of the miRNA cluster. The regulation of miR-371-373 by SMAR1 inhibits breast cancer tumorigenesis and metastasis as determined by in vivo experiments. Overall, our study highlights the binding of SMAR1 to T(C/G) repeat and its role in cancer through miR-371-373.

CRISPR-on system for the activation of the endogenous human INS gene

Advances in the field of epigenetics have allowed the design of new therapeutic strategies to address complex diseases such as type 1 diabetes (T1D). Clustered regularly interspaced short palindromic repeats (CRISPR)-on is a novel and powerful RNA-guided transcriptional activator system that can turn on specific gene expression; however, it remains unclear whether this system can be widely used or whether its use will be restricted depending on cell types, methylation promoter statuses or the capacity to modulate chromatin state. Our results revealed that the CRISPR-on system fused with transcriptional activators (dCas9-VP160) activated endogenous human INS, which is a silenced gene with a fully methylated promoter. Similarly, we observed a synergistic effect on gene activation when multiple single guide RNAs were used, and the transcriptional activation was maintained until day 21. Regarding the epigenetic profile, the targeted promoter gene did not exhibit alteration in its methylation status but rather exhibited altered levels of H3K9ac following treatment. Importantly, we showed that dCas9-VP160 acts on patients' cells in vitro, particularly the fibroblasts of patients with T1D.

Epigenetics: general characteristics and implications for oral health

Genetic information such as DNA sequences has been limited to fully explain mechanisms of gene regulation and disease process. Epigenetic mechanisms, which include DNA methylation, histone modification and non-coding RNAs, can regulate gene expression and affect progression of disease. Although studies focused on epigenetics are being actively investigated in the field of medicine and biology, epigenetics in dental research is at the early stages. However, studies on epigenetics in dentistry deserve attention because epigenetic mechanisms play important roles in gene expression during tooth development and may affect oral diseases. In addition, understanding of epigenetic alteration is important for developing new therapeutic methods. This review article aims to outline the general features of epigenetic mechanisms and describe its future implications in the field of dentistry.