miR-152 induces human dental pulp stem cell senescence by inhibiting SIRT7 expression

SIRT7 promotes dental pulp stem cells replicative senescence through desuccinylation of ROCK1

The therapeutic effectiveness of dental pulp stem cells (DPSCs) is limited. Sirtuin 7 (SIRT7) has been reported to be associated with a variety of age-related diseases. We aimed to identify the regulatory role of SIRT7 in DPSC senescence and investigate the underlying mechanism. DPSCs were isolated from healthy adults, the stem markers were verified by flow cytomerty analysis. Replicative senescence was induced in DPSCs by serial passage and cells were analyzed at PD16 and 54. DPSC senescence was evaluated by observing senescence-associated β-galactosidase (SA-β-gal) and telomerase reverse transcriptase (TERT) activity. Meanwhile, the markers of senescence levels were monitored by western blotting assay. SIRT7 protein was pulled-down, and the binding relationship between SIRT7 and ROCK1 was verified by immunoprecipitation and western blotting methods. Replicative senescence was induced in DPSCs at PD54. The number of SA-β-gal stained DPSCs significantly increased in the PD54 group while the level of TERT activity was decreased. The cyclin-dependent kinase inhibitors p53, p21, and p16, which are markers of senescence, were markedly up-regulated at PD54. SIRT7 was also found to be lowly expressed at PD54. Inhibition of SIRT7 significantly accelerated the senescence of DPSCs. Moreover, SIRT7 can bind with ROCK1, and SIRT7 could lead to ROCK1 desuccinylation at K520. Inhibited ROCK1 significantly reversed the effects of SIRT7 knockdown on regulating DPSCs senescence. Our results demonstrate that the SIRT7/ROCK1 axis plays a key role in the regulation of DPSC senescence and provide a candidate target to improve the functional and therapeutic potential of DPSCs.

Blocking of SIRT7/FOXO3a axis by miR-152-3p enhances cisplatin sensitivity in breast cancer

BACKGROUND

Cisplatin-based chemoresistance is a major obstacle for the treatment breast cancer (BC) including Triple-negative breast cancer (TNBC). SIRT7 is reportedly involved in the progression of BC, the underlining mechanism in Cisplatin-based chemoresistance in BC remains unclear. This work is to elucidate effects of SIRT7 on cisplatin resistance in breast cancer regulated by miR-152-3p.

METHODS

The RNA expression of SIRT7 and miRNAs in breast cancer were available from TCGA database. SIRT7-targeted miRNAs were predicted by TargetScan, miRanda, miRDB databases. The association of SIRT7 expression with predicted miRNA was validated by Luciferase assay. Cell apoptosis was determined by Flow cytometry. Cell viability was detected by CCK8 assay. The mRNA expression was measured by quantitative real-time polymerase chain reaction (qRT-PCR) assay. Protein expression was determined by Western blotting assay.

RESULTS

SIRT7 mRNA levels were dramatically enhanced in BC tissues compared to para-carcinoma tissues, also increased in BC patients with Cisplatin-based chemotherapy containing TNBC compared with those without. The increase of SIRT7 expression was obviously relevant to shorter survival time of them. Importantly, SIRT7 inhibition facilitated Cisplatin-induced cell apoptosis of TNBC (MDA-MB-231 and MDA-MB-468) and non- TNBC (MCF-7). Notably, miR-152-3p was predicted as a negative regulator of SIRT7 by overlapping downregulated miRNAs in BC patients treated with Cisplatin-based chemotherapy and miRNAs to target SIRT7. Mechanically, miR-152-3p blocked SIRT7 to stimulate an activation of FOXO3a, cleaved PARP1 and Caspase-3, sensitizing Cisplatin-induced apoptosis of BC cells.

CONCLUSIONS

Inhibition of SIRT7 by miR-152-3p may be a promising strategy against the resistance to cisplatin-based chemotherapy in TNBC.

Unraveling the multifaceted role of SIRT7 and its therapeutic potential in human diseases

Sirtuins, as NAD+-dependent deacetylases, are widely found in eubacteria, archaea, and eukaryotes, and they play key roles in regulating cellular functions. Among these, SIRT7 stands out as a member discovered relatively late and studied less extensively. It is localized within the nucleus and displays enzymatic activity as an NAD+-dependent deacetylase, targeting a diverse array of acyl groups. The role of SIRT7 in important cellular processes like gene transcription, cellular metabolism, cellular stress responses, and DNA damage repair has been documented in a number of studies conducted recently. These studies have also highlighted SIRT7's strong correlation with human diseases like aging, cancer, neurological disorders, and cardiovascular diseases. In addition, a variety of inhibitors against SIRT7 have been reported, indicating that targeting SIRT7 may be a promising strategy for inhibiting tumor growth. The purpose of this review is to thoroughly look into the structure and function of SIRT7 and to explore its potential value in clinical applications, offering an essential reference for research in related domains.

Potential of Dental Pulp Stem Cell Exosomes: Unveiling miRNA-Driven Regenerative Mechanisms

Human dental pulp stem cells (hDPSCs) have emerged as a promising resource in regenerative medicine due to their unique ability to secrete exosomes containing a diverse array of bioactive molecules, particularly microRNAs (miRNAs). These exosomes appear to be essential for stimulating regenerative mechanisms, especially those associated with stem cell pluripotency and tissue repair. However, several challenges such as cargo specificity and delivery efficiency need to be addressed to maximise the therapeutic potential of hDPSC-derived exosomes and miRNA-based therapies. This narrative review explores hDPSCs' potential in regenerative medicine by examining their role in tissue engineering, secretome composition, exosome function, exosomal miRNA in diverse models, and miRNA profiling. Therefore, it is imperative to sustain ongoing research on miRNA to advance clinical applications in the field of regenerative medicine and dentistry. A comprehensive understanding of the specific miRNA composition within hDPSC-derived exosomes is essential to elucidate their mechanistic roles in diverse disease states and to inform the development of innovative therapeutic strategies. These findings hold significant potential for the development of innovative regenerative therapies and emphasises the importance of establishing a strong connection between translational research discoveries and clinical applications. hDPSC-derived exosomes and miRNA-based therapies play a crucial role in immune modulation, regenerative dentistry, and tissue repair.

Sirtuins Affect Cancer Stem Cells via Epigenetic Regulation of Autophagy

Sirtuins (SIRTs) are stress-responsive proteins that regulate several post-translational modifications, partly by acetylation, deacetylation, and affecting DNA methylation. As a result, they significantly regulate several cellular processes. In essence, they prolong lifespan and control the occurrence of spontaneous tumor growth. Members of the SIRT family have the ability to govern embryonic, hematopoietic, and other adult stem cells in certain tissues and cell types in distinct ways. Likewise, they can have both pro-tumor and anti-tumor effects on cancer stem cells, contingent upon the specific tissue from which they originate. The impact of autophagy on cancer stem cells, which varies depending on the specific circumstances, is a very intricate phenomenon that has significant significance for clinical and therapeutic purposes. SIRTs exert an impact on the autophagy process, whereas autophagy reciprocally affects the activity of certain SIRTs. The mechanism behind this connection in cancer stem cells remains poorly understood. This review presents the latest findings that position SIRTs at the point where cancer cells and autophagy interact. Our objective is to highlight the various roles of distinct SIRTs in cancer stem cell-related functions through autophagy. This would demonstrate their significance in the genesis and recurrence of cancer and offer a more precise understanding of their treatment possibilities in relation to autophagy.

SIRT7: the seventh key to unlocking the mystery of aging

Aging is a chronic yet natural physiological decline of the body. Throughout life, humans are continuously exposed to a variety of exogenous and endogenous stresses, which engender various counteractive responses at the cellular, tissue, organ, as well as organismal levels. The compromised cellular and tissue functions that occur because of genetic factors or prolonged stress (or even the stress response) may accelerate aging. Over the last two decades, the sirtuin (SIRT) family of lysine deacylases has emerged as a key regulator of longevity in a variety of organisms. SIRT7, the most recently identified member of the SIRTs, maintains physiological homeostasis and provides protection against aging by functioning as a watchdog of genomic integrity, a dynamic sensor and modulator of stresses. SIRT7 decline disrupts metabolic homeostasis, accelerates aging, and increases the risk of age-related pathologies including cardiovascular and neurodegenerative diseases, pulmonary and renal disorders, inflammatory diseases, and cancer, etc. Here, we present SIRT7 as the seventh key to unlock the mystery of aging, and its specific manipulation holds great potential to ensure healthiness and longevity.

MicroRNAs Function in Dental Stem Cells as a Promising Biomarker and Therapeutic Target for Dental Diseases

Undifferentiated, highly proliferative, clonogenic, and self-renewing dental stem cells have paved the way for novel approaches to mending cleft palates, rebuilding lost jawbone and periodontal tissue, and, most significantly, recreating lost teeth. New treatment techniques may be guided by a better understanding of these cells and their potential in terms of the specificity of the regenerative response. MicroRNAs have been recognized as an essential component in stem cell biology due to their role as epigenetic regulators of the processes that determine stem cell destiny. MicroRNAs have been proven to be crucial in a wide variety of molecular and biological processes, including apoptosis, cell proliferation, migration, and necrocytosis. MicroRNAs have been recognized to control protein translation, messenger RNA stability, and transcription and have been reported to play essential roles in dental stem cell biology, including the differentiation of dental stem cells, the immunological response, apoptosis, and the inflammation of the dental pulp. Because microRNAs increase dental stem cell differentiation, they may be used in regenerative medicine to either preserve the stem cell phenotype or to aid in the development of tooth tissue. The development of novel biomarkers and therapies for dental illnesses relies heavily on progress made in our knowledge of the roles played by microRNAs in regulating dental stem cells. In this article, we discuss how dental stem cells and their associated microRNAs may be used to cure dental illness.

Current concepts of microRNA-mediated regulatory mechanisms in human pulp tissue-derived stem cells: a snapshot in the regenerative dentistry

One of the most studied class of non-coding RNAs is microRNAs (miRNAs) which regulate more than 60% of human genes. A network of miRNA gene interactions participates in stem cell self-renewal, proliferation, migration, apoptosis, immunomodulation, and differentiation. Human pulp tissue-derived stem cells (PSCs) are an attractive source of dental mesenchymal stem cells (MSCs) which comprise human dental pulp stem cells (hDPSCs) obtained from the dental pulp of permanent teeth and stem cells isolated from exfoliated deciduous teeth (SHEDs) that would be a therapeutic opportunity in stomatognathic system reconstruction and repair of other damaged tissues. The regenerative capacity of hDPSCs and SHEDs is mediated by osteogenic, odontogenic, myogenic, neurogenic, angiogenic differentiation, and immunomodulatory function. Multi-lineage differentiation of PSCs can be induced or inhibited by the interaction of miRNAs with their target genes. Manipulating the expression of functional miRNAs in PSCs by mimicking miRNAs or inhibiting miRNAs emerged as a therapeutic tool in the clinical translation. However, the effectiveness and safety of miRNA-based therapeutics, besides higher stability, biocompatibility, less off-target effects, and immunologic reactions, have received particular attention. This review aimed to comprehensively overview the molecular mechanisms underlying miRNA-modified PSCs as a futuristic therapeutic option in regenerative dentistry.

Overexpression of adrenomedullin (ADM) alleviates the senescence of human dental pulp stem cells by regulating the miR-152/CCNA2 pathway

The limitation of human dental pulp stem cells (DPSCs), which have potential application value in regenerative medicine, is that they are prone to age in vitro. Studies have shown adrenomedullin (ADM) is believed to promote the proliferation of human DPSCs, but whether it can also affect aging remains to be investigated. A lentivirus vector was used to construct human DPSCs overexpressing ADM. Senescence tests were carried out on cells of the 7th and 15th passage. Transcriptome analysis was conducted to analyze microRNA expression regulation changes after human DPSCs overexpressed ADM. H₂O₂ induced the aging model of human DPSCs, and we examined the mechanism of recovery of aging through transfection experiments with miR-152 mimic, pCDH-CCNA2, and CCNA2 siRNA. Overexpression of ADM significantly upregulated the G2/M phase ratio of human DPSCs in natural passage culture (P = 0.001) and inhibited the expression of p53 (P = 0.014), P21 ^WAF1 (P = 0.015), and P16 ^INK4A (P = 0.001). Decreased ROS accumulation was observed in human DPSCs during long-term natural passage (P = 0.022). Transcriptome analysis showed that miR-152 was significantly upregulated during human DPSC senescence (P = 0.001) and could induce cell senescence by directly targeting CCNA2. Transfection with miR-152 mimic significantly reversed the inhibitory effect of ADM overexpression on p53 (P = 0.006), P21 ^WAF1 (P = 0.012), and P16 ^INK4A (P = 0.01) proteins in human DPSCs (H₂O₂-induced). In contrast, pCDH-CCNA2 weakened the effect of the miR-152 mimic, thus promoting cell proliferation and antiaging. ADM-overexpressing human DPSCs promote cell cycle progression and resist cellular senescence through CCNA2 expression promotion by inhibiting miR-152.

SIRT7 silencing by miR-152-3p confers cell apoptosis and renal functional impairment induced by renal ischaemia/reperfusion injury

PURPOSE

Acute kidney injury (AKI) induced by renal ischaemia/reperfusion (I/R) during renal transplantation has been reported to be linked to the regulation of SIRT2, one of the members of SIRTUINS family. Current work is attempted to explore the influence and mechanism of SIRT7 in renal cell apoptosis controlled by miR-152-3p during renal I/R injury.

METHODS

Three databases were used to select the miRNAs regulating the expression of SIRT7. Overexpression and inhibition of miR-152-3p and Luciferase assay were employed to certify the modulation of miR-152-3p to SIRT7 in cells. RT-qPCR assay was used to measure the mRNA levels. Western blot assay was employed to determine the expression of proteins. TUNEL assay and Flow Cytometry were conducted to analyze cell apoptosis.

RESULTS

SIRT7 expression decreased in tissues of AKI patients and rats underwent renal I/R, which was associated with enhanced impairment of renal function. SIRT7 downregulation was attributed to the direct inhibition by miR-152-3p due to binding and inhibiting its seed sequence in 3'-UTR of SIRT7 mRNA. Consequently, the upregulation of miR-152-3p led to an inhibition of SIRT7 expression, an increase in expression of extrinsic apoptosis molecules containing FOXO3a, Bim, and caspase3, and apoptotic renal cells; while miR-152-3p inhibition abolished these phenotypes.

CONCLUSION

SIRT7 downregulation by miR-152-3p is a leading cause of renal cell apoptosis and functional impairment induced by renal I/R. Inhibition of miR-152-3p to restore SIRT7 expression can be a promising strategy against renal I/R injury.

Epigenetic regulation of dental-derived stem cells and their application in pulp and periodontal regeneration

Dental-derived stem cells have excellent proliferation ability and multi-directional differentiation potential, making them an important research target in tissue engineering. An increasing number of dental-derived stem cells have been discovered recently, including dental pulp stem cells (DPSCs), stem cells from exfoliated deciduous teeth (SHEDs), stem cells from apical papilla (SCAPs), dental follicle precursor cells (DFPCs), and periodontal ligament stem cells (PDLSCs). These stem cells have significant application prospects in tissue regeneration because they are found in an abundance of sources, and they have good biocompatibility and are highly effective. The biological functions of dental-derived stem cells are regulated in many ways. Epigenetic regulation means changing the expression level and function of a gene without changing its sequence. Epigenetic regulation is involved in many biological processes, such as embryonic development, bone homeostasis, and the fate of stem cells. Existing studies have shown that dental-derived stem cells are also regulated by epigenetic modifications. Pulp and periodontal regeneration refers to the practice of replacing damaged pulp and periodontal tissue and restoring the tissue structure and function under normal physiological conditions. This treatment has better therapeutic effects than traditional treatments. This article reviews the recent research on the mechanism of epigenetic regulation of dental-derived stem cells, and the core issues surrounding the practical application and future use of pulp and periodontal regeneration.

Cellular senescence: the good, the bad and the unknown

Cellular senescence is a ubiquitous process with roles in tissue remodelling, including wound repair and embryogenesis. However, prolonged senescence can be maladaptive, leading to cancer development and age-related diseases. Cellular senescence involves cell-cycle arrest and the release of inflammatory cytokines with autocrine, paracrine and endocrine activities. Senescent cells also exhibit morphological alterations, including flattened cell bodies, vacuolization and granularity in the cytoplasm and abnormal organelles. Several biomarkers of cellular senescence have been identified, including SA-βgal, p16 and p21; however, few markers have high sensitivity and specificity. In addition to driving ageing, senescence of immune and parenchymal cells contributes to the development of a variety of diseases and metabolic disorders. In the kidney, senescence might have beneficial roles during development and recovery from injury, but can also contribute to the progression of acute kidney injury and chronic kidney disease. Therapies that target senescence, including senolytic and senomorphic drugs, stem cell therapies and other interventions, have been shown to extend lifespan and reduce tissue injury in various animal models. Early clinical trials confirm that senotherapeutic approaches could be beneficial in human disease. However, larger clinical trials are needed to translate these approaches to patient care.

SIRT7 in the aging process

Aging is the result of the accumulation of a wide variety of molecular and cellular damage over time. This has been associated with a number of features termed hallmarks of aging, including genomic instability, loss of proteostasis, telomere attrition, dysregulated nutrient sensing, mitochondrial dysfunction, cellular senescence, stem cell exhaustion, and impaired intercellular communication. On the other hand, sirtuins are enzymes with an important role in aging and life extension, of which humans have seven paralogs (SIRT1 to SIRT7). SIRT7 is the least studied sirtuin to date, but it has been reported to serve important functions, such as promoting ribosomal RNA expression, aiding in DNA damage repair, and regulating chromatin compaction. Several studies have established a close relationship between SIRT7 and age-related processes, but knowledge in this area is still scarce. Therefore, the purpose of this review was to analyze how SIRT7 is associated with each of the hallmarks of aging, as well as with some of age-associated diseases, such as cardiovascular diseases, obesity, osteoporosis, and cancer.

Sirtuin 7 serves as a promising therapeutic target for cardiorenal diseases

Cardiovascular disorders and associated renal diseases account for the main cause of morbidity and mortality worldwide, necessitating the development of novel effective approaches for the prevention and treatment of cardiorenal diseases. Mammalian sirtuins (SIRTs) function as nicotinamide adenine dinucleotide (NAD+)-dependent protein/histone deacetylases. Seven members of SIRTs share a highly invariant catalytic core domain responsible for the specific enzymatic activity. Intriguingly, the broad distribution of SIRTs and alternative isoforms implicate its distinct functions in diverse cardiac and renal cells and tissue types. Notably, SIRT7 has been shown to exert beneficial effects in cardiorenal physiology and pathophysiology via modulation of senescence, DNA damage repair, ribosomal RNA synthesis, protein biosynthesis, angiogenesis, apoptosis, superoxide generation, cardiorenal metabolism, and dysfunction. Furthermore, SIRT7 has emerged as a critical modulator of a broad range of cellular activities including oxidative stress, inflammation response, endoplasmic reticulum stress, and mitochondrial homeostasis, which are all of great significance in postponing the progression of cardiorenal diseases. More importantly, SIRT7 has been implicated in cardiorenal hypertrophy, fibrosis, remodeling, heart failure, atherosclerosis as well as renal acid-base and electrolyte homeostasis as an essential regulator. In this review, we focus on the involvement in cardiorenal physiology and pathophysiology, diverse actions and underlying mechanisms of the SIRT7 signaling, highlighting its updated research progress in heart failure, atherosclerosis, diabetic nephropathy and other cardiorenal diseases. Targeting SIRT7 signaling could be potentially exploited as a therapeutic strategy aiming to prevent and treat cardiorenal diseases.

Versatile role of sirtuins in metabolic disorders: From modulation of mitochondrial function to therapeutic interventions

Sirtuins (SIRT1-7) are distinct histone deacetylases (HDACs) whose activity is determined by cellular metabolic status andnicotinamide adenine dinucleotide (NAD⁺ ) levels. HDACs of class III are the members of the SIRT's protein family. SIRTs are the enzymes that modulate mitochondrial activity and energy metabolism. SIRTs have been linked to a number of clinical and physiological operations, such as energy responses to low-calorie availability, aging, stress resistance, inflammation, and apoptosis. Mammalian SIRT2 orthologs have been identified as SIRT1-7 that are found in several subcellular sections, including the cytoplasm (SIRT1, 2), mitochondrial matrix (SIRT3, 4, 5), and the core (SIRT1, 2, 6, 7). For their deacetylase or ADP-ribosyl transferase action, all SIRTs require NAD⁺ and are linked to cellular energy levels. Evolutionarily, SIRT1 is related to yeast's SIRT2 as well as received primary attention in the circulatory system. An endogenous protein, SIRT1 is involved in the development of heart failure and plays a key role in cell death and survival. SIRT2 downregulation protects against ischemic-reperfusion damage. Increase in human longevity is caused by an increase in SIRT3 expression. Cardiomyocytes are also protected by SIRT3 from oxidative damage and aging, as well as suppressing cardiac hypertrophy. SIRT4 and SIRT5 perform their roles in the heart. SIRT6 has also been linked to a reduction in heart hypertrophy. SIRT7 is known to be involved in the regulation of stress responses and apoptosis in the heart.

Specific microRNAs regulate dental pulp stem cell behavior

INTRODUCTION

MicroRNAs (miRNAs), small non-coding RNA, control the translation of messenger RNAs into proteins. miRNAs have a crucial role in regulating the diverse biological processes of many physiological and pathological activities. The aim of this systematic review is to explore various functions of miRNAs in the regulation of dental pulp stem cells (DPSCs) behavior.

METHODS

The articles were searched in PubMed, SCOPUS and ISI Web of Science database using designated keywords. Full-length manuscripts published in English in peer-reviewed journals relevant to the role of miRNAs in DPSC functions were included and reviewed by 2 independent researchers.

RESULTS

The original search of the database generated 299 studies. One hundred and two duplicate studies were removed. After their exclusion, 48 studies were selected for review. miRNAs have shown to modulate the stemness and differentiation of various mesenchymal stem cells. The miRNAs expression profiles in DPSCs were differed compared with other cell types and have been demonstrated to regulate the levels of proteins crucial for promoting or inhibiting DPSC proliferation as well as differentiation. Further, miRNAs also modulate inflammatory processes in dental pulp.

CONCLUSION

miRNAs have various function upon the regulation of DPSCs and understanding these roles of miRNAs is crucial for the development of new therapeutics in regenerative dental medicine. With the advancing technologies, the utilization of miRNA technology could revolutionarily change the future of regenerative endodontics.

Deciphering the Epigenetic Code of Stem Cells Derived From Dental Tissues

Stem cells derived from dental tissues (DSCs) exhibit multipotent regenerative potential in pioneering tissue engineering regimens. The multipotency of DSCs is critically regulated by an intricate range of factors, of which the epigenetic influence is considered vital. To gain a better understanding of how epigenetic alterations are involved in the DSC fate determination, the present review overviews the current knowledge relating to DSC epigenetic modifications, paying special attention to the landscape of epigenetic modifying agents as well as the related signaling pathways in DSC regulation. In addition, insights into the future opportunities of epigenetic targeted therapies mediated by DSCs are discussed to hold promise for the novel therapeutic interventions in future translational medicine.

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.

Multifaced role of protein deacetylase sirtuins in neurodegenerative disease

Sirtuins, a class III histone/protein deacetylase, is a central regulator of metabolic function and cellular stress response. This plays a pivotal role in the pathogenesis and progression of diseases such as cancer, neurodegeneration, metabolic syndromes, and cardiovascular disease. Sirtuins regulate biological and cellular processes, for instance, mitochondrial biogenesis, lipid and fatty acid oxidation, oxidative stress, gene transcriptional activity, apoptosis, inflammatory response, DNA repair mechanism, and autophagic cell degradation, which are known components for the progression of the neurodegenerative diseases (NDDs). Emerging evidence suggests that sirtuins are the useful molecular targets against NDDs like, Alzheimer's Disease (AD), Parkinson's Disease (PD), Huntington's Disease (HD), and Amyotrophic Lateral Sclerosis (ALS). However, the exact mechanism of neuroprotection mediated through sirtuins remains unsettled. The manipulation of sirtuins activity with its modulators, calorie restriction (CR), and micro RNAs (miR) is a novel therapeutic approach for the treatment of NDDs. Herein, we reviewed the current putative therapeutic role of sirtuins in regulating synaptic plasticity and cognitive functions, which are mediated through the different molecular phenomenon to prevent neurodegeneration. We also explained the implications of sirtuin modulators, and miR based therapies for the treatment of life-threatening NDDs.

The Role of microRNAs in Pulp Inflammation

The dental pulp can be affected by thermal, physical, chemical, and bacterial phenomena that stimulate the inflammatory response. The pulp tissue produces an immunological, cellular, and vascular reaction in an attempt to defend itself and resolve the affected tissue. The expression of different microRNAs during pulp inflammation has been previously documented. MicroRNAs (miRNAs) are endogenous small molecules involved in the transcription of genes that regulate the immune system and the inflammatory response. They are present in cellular and physiological functions, as well as in the pathogenesis of human diseases, becoming potential biomarkers for diagnosis, prognosis, monitoring, and safety. Previous studies have evidenced the different roles played by miRNAs in proinflammatory, anti-inflammatory, and immunological phenomena in the dental pulp, highlighting specific key functions of pulp pathology. This systematized review aims to provide an understanding of the role of the different microRNAs detected in the pulp and their effects on the expression of the different target genes that are involved during pulp inflammation.

HMGB1 coordinates SASP-related chromatin folding and RNA homeostasis on the path to senescence

Spatial organization and gene expression of mammalian chromosomes are maintained and regulated in conjunction with cell cycle progression. This is perturbed once cells enter senescence and the highly abundant HMGB1 protein is depleted from nuclei to act as an extracellular proinflammatory stimulus. Despite its physiological importance, we know little about the positioning of HMGB1 on chromatin and its nuclear roles. To address this, we mapped HMGB1 binding genome-wide in two primary cell lines. We integrated ChIP-seq and Hi-C with graph theory to uncover clustering of HMGB1-marked topological domains that harbor genes involved in paracrine senescence. Using simplified Cross-Linking and Immuno-Precipitation and functional tests, we show that HMGB1 is also a bona fide RNA-binding protein (RBP) binding hundreds of mRNAs. It presents an interactome rich in RBPs implicated in senescence regulation. The mRNAs of many of these RBPs are directly bound by HMGB1 and regulate availability of SASP-relevant transcripts. Our findings reveal a broader than hitherto assumed role for HMGB1 in coordinating chromatin folding and RNA homeostasis as part of a regulatory loop controlling cell-autonomous and paracrine senescence.

Role of circular RNAs in visceral organ fibrosis

Circular RNAs (circRNAs) are a novel class of noncoding RNAs produced during pre-mRNA splicing and are emerging as new members of the gene regulatory network. Unlike linear RNAs, circRNAs have a unique structure with a covalently closed loop formed from the ligation of exons, introns, or both. CircRNAs are widely expressed in various organisms in a species-, tissue-, developmental stage- and disease-specific manner; circRNAs have been demonstrated to play a vital role in the pathogenesis and progression of human diseases. Fibrosis is characterized by an abnormal excessive deposition of extracellular matrix (ECM) in the extracellular space and plays important roles in many different pathologies of various organs. CircRNAs function as master regulators of gene expression to "sponge" or sequester other genes and target gene expression, transcription, splicing, etc. Increasing evidence has revealed that circRNAs are tightly associated with fibrotic diseases in various organs, including the lungs, liver, heart and kidneys. Herein, we provide the current understanding of the molecular characteristics of circRNAs and summarize the findings from circRNA studies in which the functions and mechanisms of action of circRNAs in organ fibrosis were proposed.

MicroRNA Profiling in Mesenchymal Stromal Cells: the Tissue Source as the Missing Piece in the Puzzle of Ageing

Ageing is among the main risk factors for human disease onset and the identification of the hallmarks of senescence remains a challenge for the development of appropriate therapeutic target in the elderly. Here, we compare senescence-related changes in two cell populations of mesenchymal stromal cells by analysing their miRNA profiling: Human Dental Pulp Stromal Cells (hDPSCs) and human Periosteum-Derived Progenitor Cells (hPDPCs). After these cells were harvested, total RNA extraction and whole genome miRNA profiling was performed, and DIANA-miRPath analysis was applied to find the target/pathways. Only 69 microRNAs showed a significant differential expression between dental pulp and periosteum progenitor cells. Among these, 24 were up regulated, and 45 were downregulated in hDPSCs compared to hPDPCs. Our attention was centered on miRNAs (22 upregulated and 34 downregulated) involved in common pathways for cell senescence (i.e. p53, mTOR pathways), autophagy (i.e. mTOR and MAPK pathways) and cell cycle (i.e. MAPK pathway). The p53, mTOR and MAPK signaling pathways comprised 43, 37 and 112 genes targeted by all selected miRNAs, respectively. Our finding is consistent with the idea that the embryological origin influences cell behavior and the ageing process. Our study strengthens the hypothesis that ageing is driven by numerous mediators interacting through an intricate molecular network, which affects adult stem cells self-renewal capability. Graphical abstract.

Aging and Senescence of Dental Pulp and Hard Tissues of the Tooth

The ability to consume a meal using one's own teeth influences an individual's quality of life. In today's global aging society, studying the biological changes in aging teeth is important to address this issue. A tooth includes three hard tissues (enamel, dentin, and cementum) and a soft tissue (dental pulp). With advancing age, these tissues become senescent; each tissue exhibits a unique senescent pattern. This review discusses the structural alterations of hard tissues, as well as the molecular and physiological changes in dental pulp cells and dental pulp stem cells during human aging. The significance of senescence in these cells remains unclear. Thus, there is a need to define the regulatory mechanisms of aging and senescence in these cells to aid in preservation of dental health.

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.

Knockdown of microRNA-584 promotes dental pulp stem cells proliferation by targeting TAZ

Proliferation of dental pulp stem cells (DPSCs) is crucial in tooth development and damage repairing, also includes its therapy application for tissue engineering. MicroRNAs (miRNAs) are key players in biological processes of DPSCs, and transcriptional co-activator with PDZ-binding motif (TAZ) also plays important roles in cell proliferation and differentiation, however, the roles of miR-584 and TAZ in DPSCs are not known. We found up-regulated miR-584 expression and down-regulated TAZ expression levels in aging dental pulp tissue compare to those in young dental pulp tissue. In proliferating DPSCs we demonstrated the decreased miR-584 expression and increased TAZ expression. miR-584 mimics suppressed DPSCs proliferation and migration, and significantly reduced TAZ production, whereas miR-584 inhibition exerted the converse effects. Knocking down of the TAZ in DPSCs had a similar effect as overexpression of miR-584. Furthermore, luciferase reporter assay demonstrated that miR-584 could directly bind to the TAZ mRNA 3'UTR to repress its translation. Overexpression of TAZ can partly rescue miR-584 mimic-mediated the inhibition of proliferation. Additionally, miR-584 inhibited cell proliferation and downregulated expression of cell cycle proteins by AKT signaling pathway. Together, we identified that miR-584 may be a key regulator in the proliferation of DPSCs by regulating TAZ expression via AKT signaling pathway. It would be a promising biomarker and therapeutic target for pulp disease.

MiR-141-3p regulates proliferation and senescence of stem cells from apical papilla by targeting YAP

Biological phenotypes of mesenchymal stem cells (MSCs) are regulated by a series of biochemical elements, including microRNAs, hormones and growth factors. Our previous study illustrated a significant role of miR-141-3p during the osteogenic differentiation of stem cells from apical papilla (SCAPs). Nevertheless, the functions of miR-141-3p in regulating the proliferative ability and senescence of SCAPs have not been determined. This study identified that overexpression of miR-141-3p inhibited the proliferative ability of SCAPs. Meanwhile, the senescence of SCAPs was ahead of time. Conversely, transfection of miR-141-3p inhibitor promoted the proliferative ability of SCAPs and delayed their senescence. Yes-associated protein (YAP) was predicted as the downstream target gene of miR-141-3p by online softwares (miRDB, miRTarBase, miRWalk, and TargetScan), and was further verified by dual-luciferase reporter gene assay. Additionally, knockdown of YAP inhibited the proliferation and accelerated the senescence of SCAPs. Collectively, these findings proposed a novel direction that miR-141-3p impeded proliferative ability and promoted senescence of SCAPs through post-transcriptionally downregulating YAP.

Short telomeres correlate with a strong induction of cellular senescence in human dental follicle cells

BACKGROUND

Dental follicle cells (DFCs) are dental stem cells and interesting options for regenerative therapies in dentistry. However, DFCs acquire replicative senescence in long-term cultures, but little is known about molecular processes. In previous studies, we observed that DFC cell lines become senescent at different rates. We hypothesized that short telomere length and increased DNA damage with genomic instability correlate with the accelerated induction of cellular senescence.

RESULTS

For this study we compared DFC cell lines that became senescent at different rates (DFC_F: strong senescent phenotype; DFC_S: weak senescent phenotype). The telomeres of DFC_F were shorter than those of the telomeres of DFC_S prior senescence. Interestingly, telomere lengths of both cell lines were nearly unchanged after induction of senescence. Gene expression analyses with genes associated with DNA damage before and after the induction of cellular senescence revealed that almost all genes in DFCs_F were down-regulated while the gene expression in DFC_S was almost constitutive. Moreover, number of aneuploid DFC_F were significantly higher after induction of cellular senescence.

CONCLUSION

Our results supported our initial hypothesis that telomere length and genomic instability correlate with the accelerated induction of cellular senescence in DFC_F.

Cellular senescence in dental pulp stem cells

OBJECTIVE

This short review summarizes our current knowledge about dental stem cell aging and about possible targets for the regulation of cellular senescence.

DESIGN

A literature search was performed using a combination of keywords, e.g., stem cells, replicative senescence, differentiation potential, dental pulp, dental follicle and periodontal ligament.

RESULTS

Previous studies have shown that cellular senescence occurs while the proliferation of dental stem cells. Moreover, the differentiation potential was significantly decreased in senescent stem cells and senescent cells secrete also factors that are harmful to the adjacent tissue cells. Moreover, many targets for the regulation of cellular senescence are considered; for example pathways related to the nutrient sensing such as the 5' adenosine monophosphate-activated protein kinase (AMPK) pathway.

CONCLUSIONS

The regulation of cellular senescence will play a crucial role in the clinical use of stem cells. However, there is no cell culture protocol available that prevents dental stem cell senescence. Therefore, more knowledge about molecular processes in stem cells is needed before and after the induction of senescence.

The Emerging Roles of microRNAs in Stem Cell Aging

Aging is the continuous loss of tissue and organ function over time. MicroRNAs (miRNAs) are thought to play a vital role in this process. miRNAs are endogenous small noncoding RNAs that control the expression of target mRNA. They are involved in many biological processes such as developmental timing, differentiation, cell death, stem cell proliferation and differentiation, immune response, aging and cancer. Accumulating studies in recent years suggest that miRNAs play crucial roles in stem cell division and differentiation. In the present chapter, we present a brief overview of these studies and discuss their contributions toward our understanding of the importance of miRNAs in normal and aged stem cell function in various model systems.

An overview of Sirtuins as potential therapeutic target: Structure, function and modulators

Sirtuin (Yeast Silent Information RegulatorsⅡ, Sir2) was first discovered in the 1970s. Because of its function by removing acetylated groups from histones in the presence of nicotinamide adenine dinucleotide (NAD⁺), waves of research have assessed the potential of Sirtuin as a therapeutic target. The Sirtuin family, which is widely distributed throughout the nature, has been divided into seven human isoforms (Sirt1-Sirt7). They are thought to be closely related to some aging diseases such as cardiovascular disorders, neurodegeneration, and tumors. Herein, we present a comprehensive review of the structure, function and modulators of Sirtuins, which is expected to be beneficial to relevant studies.

Downregulated microRNA-488 enhances odontoblast differentiation of human dental pulp stem cells via activation of the p38 MAPK signaling pathway

Human dental pulp stem cells (hDPSCs) are primarily derived from the pulp tissues of permanent third molar teeth. They were widely used in human bone tissue engineering. It was previously indicated that microRNA (miR) expressions are closely associated with hDPSCs development. However, the specific effect of miR-488 on hDPSCs still remains unclear. In this study, we aimed to investigate effects of miR-488 on the differentiation of hDPSCs into odontoblast cells through the p38 mitogen-activated protein kinases (MAPK) signaling pathway by binding to MAPK1. The hDPSCs were isolated and cultured in vitro. Dual-luciferase reporter gene assay was performed to test the relationship between MAPK1 (p38) and miR-488. Reverse transcription quantitative polymerase chain reaction and western blot analysis were used to detect the mRNA and protein expressions of p38 MAPK signaling pathway-related genes (MAPK1, Ras, and Mitogen-activated protein kinase kinase 3/6 [MKK3/6]), along with expressions of dentin Sialophosphoprotein (DSPP), alkaline phosphatase (ALP), and osteonectin (OCN). ALP staining and alizarin red staining were conducted to detect ALP activity and degree of mineralization. Initially, we found that MAPK1 was the target gene of miR-488. Besides, downregulation of miR-488 was observed to stimulate the p38 MAPK signaling pathway and to increase the messenger RNA and protein expressions of DSPP, ALP, and OCN. Furthermore, ALP activity and formation of a mineralized nodule in hDPSCs were enhanced upon downregulation of miR-488. The aforementioned findings provided evidence supporting that downregulation of miR-488 promotes odontoblastic differentiation of hDPSCs through the p38 MAPK signaling pathway by targeting MAPK1, paving the basis for further study about hDPSCs.

Characteristics of circular RNA expression in lung tissues from mice with hypoxia‑induced pulmonary hypertension

Pulmonary hypertension (PH) is a life-threatening lung disease, characterized by an increase in pulmonary arterial pressure caused by vasoconstriction and vascular remodeling. The pathogenesis of PH is not fully understood, and there is a lack of potential biomarkers for the diagnosis and treatment of patients with PH. Non-coding RNAs with a characteristic covalently closed loop structure, termed circular RNAs (circRNAs), are present in a number of pulmonary diseases. To the best of our knowledge, the present study is the first to use microarray analysis to determine the expression profile of circRNAs in lung tissues from mice with hypoxia-induced PH. In total, 23 significantly upregulated and 41 significantly down-regulated circRNAs were identified. Of these, 12 differentially expressed circRNAs were selected for further validation using reverse transcription-quantitative polymerase chain reaction. Putative microRNAs (miRNAs) that bind to the dysregulated circRNAs were predicted. Subsequently, bioinformatics tools were used to construct circRNA-miRNA-mRNA networks for the two most promising circRNAs, namely mmu_circRNA_004592 and mmu_circRNA_018351. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes analyses of target genes of the dysregulated circRNAs revealed that these dysregulated circRNAs may serve an important role in the pathogenesis of hypoxia-induced PH. Therefore, these dysregulated circRNAs are candidate diagnostic biomarkers and potential therapeutic targets for PH.

MicroRNA-340 inhibits the growth and invasion of angiosarcoma cells by targeting SIRT7

MicroRNAs (miRNAs) are emerging as critical regulators for the development and progression of various cancers, including angiosarcoma. Accumulating evidence suggests that miRNA-340 (miR-340) is an important cancer-associated miRNA. However, little is known about the role of miR-340 in angiosarcoma. In this study, we aimed to investigate the potential biological functions of miR-340 and its potential target gene in angiosarcoma. Our results showed that miR-340 expression was significantly decreased in angiosarcoma compared with normal controls. The overexpression of miR-340 inhibited the growth and invasion of angiosarcoma cells, while the inhibition of miR-340 showed the opposite effect. Bioinformatics analysis predicted that Sirtuin 7 (SIRT7) was a potential target gene of miR-340. The binding relationship between miR-340 and the SIRT7 3'-untranslated region was verified by dual-luciferase reporter assay. Moreover, our results showed that miR-340 negatively regulated SIRT7 expression in angiosarcoma cells and an inverse correlation between miR-340 and SIRT7 expression was shown in clinical angiosarcoma tissues. We found that silencing SIRT7 significantly inhibited the proliferation and invasion of angiosarcoma cells. Notably, the overexpression of SIRT7 promoted the proliferation and invasion of angiosarcoma cells and also partially reversed the antitumor effect of miR-340 on angiosarcoma cell proliferation and invasion. Taken together, our results demonstrate that miR-340 inhibits the growth and invasion of angiosarcoma cells by targeting SIRT7. Our study provides evidence that the miR-340/SIRT7 axis may play an important role in the molecular pathogenesis of angiosarcoma and suggests that miR-340 and SIRT7 may be used as potential and novel therapeutic targets for the treatment of angiosarcoma.

The role of Foxq1 in proliferation of human dental pulp stem cell

This study aimed to investigate the role for Foxq1 in proliferation activity regulation of dental pulp stem cells (DPSCs). Proliferation of DPSC was induced by calcium hydroxide, then expression alteration of Foxq1 was evaluated. Lentivirus was employed to manipulate Foxq1 level in DPSC, and proliferation activities were evaluated. To look into mechanism regulating Foxq1 level after calcium hydroxide stimulation, expressions of various microRNAs were evaluated, then bioinformatics study and dual-luciferase study were carried out to confirm targeting relationship between microRNA and Foxq1. The result of our study indicated that proliferation activities of DPSCs were enhanced after calcium hydroxide stimulation, during which expression of Foxq1 was also up-regulated. Cell viability and progression from G1 to S phase were both improved with overexpression of Foxq1, and microRNAs profiling study and dual-luciferase result suggested miR-320b contributed to the up-regulation of Foxq1 after calcium hydroxide stimulation. These results suggested that miR-320b mediated Foxq1 up-regulation promote proliferation of dental pulp stem cells.

MicroRNA-519d inhibits proliferation and induces apoptosis of human hypertrophic scar fibroblasts through targeting Sirtuin 7

MicroRNAs (miRNAs) play critical roles in various pathological processes, including hypertrophic scar (HS) formation. However, the precise role of miRNAs in HS formation remains largely unknown. In this study, we aimed to investigate the role of miR-519d in HS formation. We found that miR-519d expression was significantly downregulated in HS tissues and fibroblasts. Overexpression of miR-519d inhibited the expression of type I collagen (Col I), type III collagen (Col III) and α-smooth muscle actin (α-SMA) in HS fibroblasts. Moreover, overexpression of miR-519d reduced the proliferation and induced the apoptosis of HS fibroblasts. In contrast, suppression of miR-519d showed the opposite effects. Interestingly, Sirtuin 7 (SIRT7) was identified as a target gene of miR-519d. The results showed that miR-519d directly targeted the 3'-untranslated region of SIRT7 and negatively regulated its expression. Furthermore, miR-519d regulated the expression of TGF-β type I receptor (TGFBRI) and the phosphorylation of Smad2. Knockdown of SIRT7 by siRNA inhibited the expression of Col I, Col III and α-SMA, and reduced the proliferation and induced the apoptosis of HS fibroblasts. Overexpression of SIRT7 abrogated the effects mediated by miR-519d overexpression in HS fibroblasts. Overall, these results suggest that miR-519d inhibits the expression of extracellular matrix-associated genes, reduces the proliferation and induces the apoptosis of HS fibroblasts by targeting SIRT7, implying a suppressive role of miR-519d in HS formation. This study suggests that miR-519d may serve as a promising therapeutic target for treatment of human HS.

Dental stem cells in tooth regeneration and repair in the future

INTRODUCTION

Human dental stem cells can be obtained from postnatal teeth, extracted wisdom teeth or exfoliated deciduous teeth. Due to their differentiation potential, these mesenchymal stem cells are promising for tooth repair. Therefore, the development of dental tissue regeneration represents a suitable but challenging, target for dental stem cell therapies. Areas covered: Expert opinion:

AREAS COVERED

In this review, the authors provide an overview of human dental stem cells and their properties for regeneration medicine. Numerous preclinical studies have shown that dental stem cells improve bone augmentation and healing of periodontal diseases. Clinical trials are ongoing to validate the clinical feasibility of these approaches. Dental stem cells are also important for basic research.

EXPERT OPINION

Dental stem cells offer numerous advantages for tooth repair and regeneration. Data obtained from different studies are encouraging. In the next few years, investigations on dental stem cells in basic research, pre-clinical research and clinical studies will pave the way to optimizing patient-tailored treatments for repair and regeneration of dental tissues.

MicroRNA‑3666 inhibits breast cancer cell proliferation by targeting sirtuin 7

The abnormal expression of microRNAs (miRNAs) is associated with cancer initiation and progression. miRNAs functioning as oncogenes or tumor suppressors represent novel biomarkers for cancer diagnosis, prognosis, and serve as therapeutic tools. MiR‑3666 has been reported as a tumor suppressor in various types of cancer; however, its role in breast cancer remains unknown. In the current study, the aim was to investigate the potential role of miR‑3666 in breast cancer. It was identified that miR‑3666 was decreased in breast cancer cell lines and that the overexpression of miR‑3666 inhibited breast cancer cell proliferation. Furthermore, miR‑3666 promotes cell apoptosis of breast cancer cells. Bioinformatics analysis and dual‑luciferase reporter assay demonstrated that miR‑3666 targeted the 3'‑untranslated region of sirtuin 7 (SIRT7) which was recognized as an oncogene. Overexpression of miR‑3666 decreased SIRT7 expression levels, and knockdown of SIRT7 suppressed proliferation and promoted apoptosis of breast cancer cells. A rescue assay demonstrated that the restoration of SIRT7 expression markedly reversed the miR‑3666‑induced anti‑tumor effects. Thus, the current study indicates that miR‑3666 suppresses breast cancer cell proliferation by targeting SIRT7, and propose miR‑3666 as a potential candidate for breast cancer therapy.