The Multiple Roles of Microrna-223 in Regulating Bone Metabolism

Concomitant induction of SLIT3 and microRNA-218-2 in macrophages by toll-like receptor 4 activation limits osteoclast commitment

BACKGROUND

Toll-like receptor 4 (TLR4) conducts a highly regulated inflammatory process by limiting the extent of inflammation to avoid toxicity and tissue damage, even in bone tissues. Thus, it is plausible that strategies for the maintenance of normal bone-immunity to prevent undesirable bone damage by TLR4 activation can exist, but direct evidence is still lacking.

METHODS

Osteoclast precursors (OCPs) obtained from WT or Slit3-deficient mice were differentiated into osteoclast (OC) with macrophage colony-stimulating factor (M-CSF), RANK ligand (RANKL) and lipopolysaccharide (LPS) by determining the number of TRAP-positive multinuclear cells (TRAP+ MNCs). To determine the alteration of OCPs population, fluorescence-activated cell sorting (FACS) was conducted in bone marrow cells in mice after LPS injection. The severity of bone loss in LPS injected WT or Slit3-deficient mice was evaluated by micro-CT analysis.

RESULT

We demonstrate that TLR4 activation by LPS inhibits OC commitment by inducing the concomitant expression of miR-218-2-3p and its host gene, Slit3, in mouse OCPs. TLR4 activation by LPS induced SLIT3 and its receptor ROBO1 in BMMs, and this SLIT3-ROBO1 axis hinders RANKL-induced OC differentiation by switching the protein levels of C/EBP-β isoforms. A deficiency of SLIT3 resulted in increased RANKL-induced OC differentiation, and the elevated expression of OC marker genes including Pu.1, Nfatc1, and Ctsk. Notably, Slit3-deficient mice showed expanded OCP populations in the bone marrow. We also found that miR-218-2 was concomitantly induced with SLIT3 expression after LPS treatment, and that this miRNA directly suppressed Tnfrsf11a (RANK) expression at both gene and protein levels, linking it to a decrease in OC differentiation. An endogenous miR-218-2 block rescued the expression of RANK and subsequent OC formation in LPS-stimulated OCPs. Aligned with these results, SLIT3-deficient mice displayed increased OC formation and reduced bone density after LPS challenge.

CONCLUSION

Our findings suggest that the TLR4-dependent concomitant induction of Slit3 and miR-218-2 targets RANK in OCPs to restrain OC commitment, thereby avoiding an uncoordinated loss of bone through inflammatory processes. These observations provide a mechanistic explanation for the role of TLR4 in controlling the commitment phase of OC differentiation. Video Abstract.

Osteoimmune Interactions and Therapeutic Potential of Macrophage-Derived Small Extracellular Vesicles in Bone-Related Diseases

Due to the aging of the global population, the burden of bone-related diseases has increased sharply. Macrophage, as indispensable components of both innate immune responses and adaptive immunity, plays a considerable role in maintaining bone homeostasis and promoting bone establishment. Small extracellular vesicles (sEVs) have attracted increasing attention because they participate in cell cross-talk in pathological environments and can serve as drug delivery systems. In recent years, an increasing number of studies have expanded our knowledge about the effects of macrophage-derived sEVs (M-sEVs) in bone diseases via different forms of polarization and their biological functions. In this review, we comprehensively describe on the application and mechanisms of M-sEVs in various bone diseases and drug delivery, which may provide new perspectives for treating and diagnosing human bone disorders, especially osteoporosis, arthritis, osteolysis, and bone defects.

Specific microRNAs are associated with fracture healing phases, patient age and multi-trauma

Background

Methods

Results

Conclusion

The Translational Potential of this Article

MicroRNA-223 negatively regulates the osteogenic differentiation of periodontal ligament derived cells by directly targeting growth factor receptors

Background

MicroRNA (miRNA) is accepted as a critical regulator of cell differentiation. However, whether microRNA-223 (miR-223) could affect the osteogenic differentiation of periodontal ligament (PDL)-derived cells is still unknown. The aim of this study was to explore the mechanisms underlying the roles of miR-223 in the osteogenesis of PDL-derived cells in periodontitis.

Methods

Microarray analysis and real-time polymerase chain reaction (RT-PCR) were used to identify difference in miR-223 expression pattern between healthy and inflamed gingival tissue. The target genes of miR-223 were predicted based on Targetscan and selected for enrichment analyses based on Metascape database. The gain-and loss-of-function experiments were performed to discuss roles of miR-223 and growth factor receptor genes in osteogenic differentiation of PDL-derived cells. The target relationship between miR-223 and growth factor receptor genes was confirmed by a dual luciferase assay. Osteogenic differentiation of PDL-derived cells was assessed by Alizarin red staining, RT-PCR and western blot detection of osteogenic markers, including osteocalcin (OCN), osteopontin (OPN) and runt-related transcription factor 2 (Runx2).

Results

MiR-223 was significantly increased in inflamed gingival tissues and down-regulated in PDL-derived cells during osteogenesis. The expression of miR-223 in gingival tissues was positively correlated with the clinical parameters in periodontitis patients. Overexpression of miR-223 markedly inhibited PDL-derived cells osteogenesis, which was evidenced by reduced Alizarin red staining and osteogenic markers expressions. Furthermore, two growth factor receptor genes, including fibroblast growth factor receptor 2 (FGFR2) and transforming growth factor beta receptor 2 (TGFβR2), were revealed to be direct targets of miR-223 and shown to undergo up-regulation in PDL-derived cells during osteogenesis. Moreover, suppression of FGFR2 or TGFβR2 dramatically blocked PDL-derived cells osteogenic differentiation.

Conclusions

Our study provides novel evidence that miR-223 can be induced by periodontitis and acts as a negative regulator of PDL-derived cells osteogenesis by targeting two growth factor receptors (TGFβR2 and FGFR2).

Supplementary Information

The online version contains supplementary material available at 10.1186/s12967-022-03676-1.

Co-regulation of circadian clock genes and microRNAs in bone metabolism

Mammalian bone is constantly metabolized from the embryonic stage, and the maintenance of bone health depends on the dynamic balance between bone resorption and bone formation, mediated by osteoclasts and osteoblasts. It is widely recognized that circadian clock genes can regulate bone metabolism. In recent years, the regulation of bone metabolism by non-coding RNAs has become a hotspot of research. MicroRNAs can participate in bone catabolism and anabolism by targeting key factors related to bone metabolism, including circadian clock genes. However, research in this field has been conducted only in recent years and the mechanisms involved are not yet well established. Recent studies have focused on how to target circadian clock genes to treat some diseases, such as autoimmune diseases, but few have focused on the co-regulation of circadian clock genes and microRNAs in bone metabolic diseases. Therefore, in this paper we review the progress of research on the co-regulation of bone metabolism by circadian clock genes and microRNAs, aiming to provide new ideas for the prevention and treatment of bone metabolic diseases such as osteoporosis.

PARP-1 modulates the expression of miR-223 through histone acetylation to involve in the hydroquinone-induced carcinogenesis of TK6 cells

The upstream regulators of microRNAs were rarely reported. Hydroquinone (HQ) is the main metabolite of benzene, one of the important environmental factors contributing to leukemia and lymphoma. In HQ-induced malignant transformed TK6 (TK6-HT) cells, the expression of PARP-1 and miR-223 were upregulated. When in PARP-1 silencing TK6-HT cells, miR-223 was downregulated and the apoptotic cell number correspondingly increased. In TK6 cells treated with HQ for different terms, the expression of miR-223 and PARP-1 were dynamically observed and found to be decreased and increased, respectively. Trichostatin A could increase the expression of miR-223, then the expression of HDAC1-2 and nuclear factor kappa B were found to be increased, but that of mH2A was decreased. PARP-1 silencing inhibited the protein expression of H3Ac, mH2A, and H3K27ac. By co-immunoprecipitation experiment, PARP-1 and HDAC2 were found to form a regulatory complex. In conclusion, we demonstrated that the upregulation of PARP-1 mediated activation of acetylation to promote the transcription of miR-223 possibly via coregulating with HDAC2, an epigenetic regulation mechanism involved in cell malignant transformation resulting from long-term exposure to HQ, in which course, H3K27ac might be a specific marker for the activation of histone H3, which also gives hints for benzene exposure research.

Dynamic mRNA and miRNA expression of the head during early development in bighead carp (Hypophthalmichthys nobilis)

Background

Head of fish species, an exquisitely complex anatomical system, is important not only for studying fish evolution and development, but also for economic values. Currently, although some studies have been made on fish growth and body shapes, very limited information is available on the molecular mechanism of head development.

Results

In this study, RNA sequencing (RNA–Seq) and small RNA sequencing (sRNA–Seq) technologies were used to conduct integrated analysis for the head of bighead carp at different development stages, including 1, 3, 5, 15 and 30 Dph (days post hatch). By RNA-Seq data, 26 pathways related to growth and bone formation were identified as the main physiological processes during early development. Coupling this to sRNA–Seq data, we picked out six key pathways that may be responsible for head development, namely ECM receptor interaction, TNF signaling pathway, osteoclast differentiation, PI3K–Akt signaling pathway, Neuroactive ligand–receptor interaction and Jak–STAT signaling pathway. Totally, 114 important candidate genes from the six pathways were obtained. Then we found the top 20 key genes according to the degree value by cytohubba, which regulated cell growth, skeletal formation and blood homeostasis, such as pik3ca, pik3r1, egfr, vegfa, igf1 and itga2b. Finally, we also acquired 19 key miRNAs playing multiple roles in the perfection of various tissues in the head (such as brain, eye and mouth) and mineralization of head bone system, such as let–7e, miR–142a–5p, miR–144–3p, miR–23a–3p and miR–223.

Conclusions

Results of this study will be informative for genetic mechanisms of head development and also provide potential candidate targets for the interaction regulation during early growth in bighead carp.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12864-022-08387-x.

Whole-exome sequencing in syndromic craniosynostosis increases diagnostic yield and identifies candidate genes in osteogenic signaling pathways

Craniosynostosis (CS) is a common congenital anomaly defined by premature fusion of one or more cranial sutures. Syndromic CS involves additional organ anomalies or neurocognitive deficits and accounts for 25%-30% of the cases. In a recent population-based study by our group, 84% of the syndromic CS cases had a genetically verified diagnosis after targeted analyses. A number of different genetic causes were detected, confirming that syndromic CS is highly heterogeneous. In this study, we performed whole-exome sequencing of 10 children and parents from the same cohort where previous genetic results were negative. We detected pathogenic, or likely pathogenic, variants in four additional genes (NFIA, EXTL3, POLR2A, and FOXP2) associated with rare conditions. In two of these (POLR2A and FOXP2), CS has not previously been reported. We further detected a rare predicted damaging variant in SH3BP4, which has not previously been related to human disease. All findings were clustered in genes involved in the pathways of osteogenesis and suture patency. We conclude that whole-exome sequencing expands the list of genes associated with syndromic CS, and provides new candidate genes in osteogenic signaling pathways.

GATA4 regulates osteogenic differentiation by targeting miR-144-3p

Numerous studies have demonstrated that microRNAs (miRNAs or miRs) play an important role in regulating osteogenic differentiation, but their specific regulatory mechanism requires further investigation. In the present study, it was revealed that during osteogenic differentiation of rat bone marrow mesenchymal stem cells (BMSCs), the expression level of miR-144-3p was decreased with increased osteogenic induction duration and was negatively associated with osteogenic marker gene expression. Overexpression of miR-144-3p inhibited osteogenic differentiation, while inhibition of miR-144-3p expression promoted osteogenic differentiation. In addition, dual-luciferase activity analysis and adenovirus infection experiments revealed that GATA binding protein 4 targeted miR-144-3p for regulation and that overexpression of GATA4 promoted the expression of miR-144-3p. These data indicated that miR-144-3p plays a role in inhibiting BMSC osteogenic differentiation and that GATA4 inhibits osteogenic differentiation by targeting miR-144-3p expression.

MiRNAs Expression Profiling in Raw264.7 Macrophages after Nfatc1-Knockdown Elucidates Potential Pathways Involved in Osteoclasts Differentiation

Differentiation of macrophages toward osteoclasts is crucial for bone homeostasis but can be detrimental in disease states, including osteoporosis and cancer. Therefore, understanding the osteoclast differentiation process and the underlying regulatory mechanisms may facilitate the identification of new therapeutic targets. Hereby, we tried to reveal new miRNAs potentially involved in the regulation of early steps of osteoclastogenesis, with a particular focus on those possibly correlated with NFATc1 expression, by studying miRNAs profiling. During the first 24 h of osteoclastogenesis, 38 miRNAs were differentially expressed between undifferentiated and RANKL-stimulated RAW264.7 cells, while 10 miRNAs were differentially expressed between RANKL-stimulated cells transfected with negative control or NFATc1-siRNAs. Among others, the expression levels of miR-411, miR-144 and members of miR-29, miR-30, and miR-23 families changed after RANKL stimulation. Moreover, the potential role of miR-124 during osteoclastogenesis was explored by transient cell transfection with anti-miR-124 or miR-124-mimic. Two relatively unknown miRNAs, miR-880-3p and miR-295-3p, were differentially expressed between RANKL-stimulated/wild-type and RANKL-stimulated/NFATc1-silenced cells, suggesting their possible correlation with NFATc1. KEGG enrichment analyses showed that kinase and phosphatase enzymes were among the predicted targets for many of the studied miRNAs. In conclusion, our study provides new data on the potential role and possible targets of new miRNAs during osteoclastogenesis.

Regulation of Osteoclastogenesis and Bone Resorption by miRNAs

Osteoclasts are specialized bone-resorbing cells that contribute to physiological bone development and remodeling in bone metabolism throughout life. Abnormal production and activation of osteoclasts lead to excessive bone resorption in pathological conditions, such as in osteoporosis and in arthritic diseases with bone destruction. Recent epigenetic studies have shed novel insight into the dogma of the regulation of gene expression. microRNAs belong to a category of epigenetic regulators, which post-transcriptionally regulate and silence target gene expression, and thereby control a variety of biological events. In this review, we discuss miRNA biogenesis, the mechanisms utilized by miRNAs, several miRNAs that play important roles in osteoclast differentiation, function, survival and osteoblast-to-osteoclast communication, and their translational potential and challenges in bone biology and skeletal diseases.

Bone remodeling stages under physiological conditions and glucocorticoid in excess: Focus on cellular and molecular mechanisms

This review provides a rationale for the cellular and molecular mechanisms of bone remodeling stages under physiological conditions and glucocorticoids (GCs) in excess. Remodeling is a synchronous process involving bone resorption and formation, proceeding through stages of: (1) resting bone, (2) activation, (3) bone resorption, (4) reversal, (5) formation, (6) termination. Bone remodeling is strictly controlled by local and systemic regulatory signaling molecules. This review presents current data on the interaction of osteoclasts, osteoblasts and osteocytes in bone remodeling and defines the role of osteoprogenitor cells located above the resorption area in the form of canopies and populating resorption cavities. The signaling pathways of proliferation, differentiation, viability, and cell death during remodeling are presented. The study of signaling pathways is critical to understanding bone remodeling under normal and pathological conditions. The main signaling pathways that control bone resorption and formation are RANK / RANKL / OPG; M-CSF – c-FMS; canonical and non-canonical signaling pathways Wnt; Notch; MARK; TGFβ / SMAD; ephrinB1/ephrinB2 – EphB4, TNFα – TNFβ, and Bim – Bax/Bak. Cytokines, growth factors, prostaglandins, parathyroid hormone, vitamin D, calcitonin, and estrogens also act as regulators of bone remodeling. The role of non-encoding microRNAs and long RNAs in the process of bone cell differentiation has been established. MicroRNAs affect many target genes, have both a repressive effect on bone formation and activate osteoblast differentiation in different ways. Excess of glucocorticoids negatively affects all stages of bone remodeling, disrupts molecular signaling, induces apoptosis of osteocytes and osteoblasts in different ways, and increases the life cycle of osteoclasts. Glucocorticoids disrupt the reversal stage, which is critical for the subsequent stages of remodeling. Negative effects of GCs on signaling molecules of the canonical Wingless (WNT)/β-catenin pathway and other signaling pathways impair osteoblastogenesis. Under the influence of excess glucocorticoids biosynthesis of biologically active growth factors is reduced, which leads to a decrease in the expression by osteoblasts of molecules that form the osteoid. Glucocorticoids stimulate the expression of mineralization inhibitor proteins, osteoid mineralization is delayed, which is accompanied by increased local matrix demineralization. Although many signaling pathways involved in bone resorption and formation have been discovered and described, the temporal and spatial mechanisms of their sequential turn-on and turn-off in cell proliferation and differentiation require additional research.

Current Status of MicroRNAs that Target the Wnt Signaling Pathway in Regulation of Osteogenesis and Bone Metabolism: A Review

The directional differentiation of bone mesenchymal stem cells (BMSCs) is regulated by a variety of transcription factors and intracellular signaling pathways. In the past, it was thought that the directional differentiation of BMSCs was related to transforming growth factors, such as bone morphogenetic protein (BMP) and MAPK pathway. However, in recent years, some scholars have pointed out that the Wnt signaling pathway, which is a necessary complex network of protein interactions for biological growth and development, takes a significant role in this process and plays a major part in regulating the development of osteoblasts by exerting signal transduction into cells. Also, they have proved the Wnt protein therapeutic truly have positive effects on the viability and osteogenic capacity of bone graft. Recent studies have shown that microRNAs (miRNAs) play an important regulatory role in this process. MiRNAs such as miRNA-218, miRNA-335, miRNA-29, microRNA-30 and other miRNAs exert negative or positive effects on some crucial molecules in the Wnt/β-catenin pathway, which in turn affect bone metabolism and osteopathy. Thus, miRNAs have been suggested as therapeutic targets for some metabolic bone diseases. This article aims to provide an update on the current status of microRNAs that target the Wnt signaling pathway in the regulation of osteogenesis and bone metabolism and includes a discussion of future areas of research, which can be a theoretical basis for bone metabolism-related diseases.

Multiple Myeloma Bone Disease: Implication of MicroRNAs in Its Molecular Background

Multiple myeloma (MM) is a common hematological malignancy arising from terminally differentiated plasma cells. In the majority of cases, symptomatic disease is characterized by the presence of bone disease. Multiple myeloma bone disease (MMBD) is a result of an imbalance in the bone-remodeling process that leads to increased osteoclast activity and decreased osteoblast activity. The molecular background of MMBD appears intriguingly complex, as several signaling pathways and cell-to-cell interactions are implicated in the pathophysiology of MMBD. MicroRNAs (miRNAs) are small non-coding RNA molecules that regulate the expression of their target mRNAs. Numerous miRNAs have been witnessed to be involved in cancer and hematological malignancies and their role has been characterized either as oncogenic or oncosuppressive. Recently, scientific research turned towards miRNAs as regulators of MMBD. Scientific data support that miRNAs finely regulate the majority of the signaling pathways implicated in MMBD. In this review, we provide concise information regarding the molecular pathways with a significant role in MMBD and the miRNAs implicated in their regulation. Moreover, we discuss their utility as molecular biomarkers and highlight the putative usage of miRNAs as novel molecular targets for targeted therapy in MMBD.

Involvement of Noncoding RNAs in the Differentiation of Osteoclasts

As the most important bone-resorbing cells, osteoclasts play fundamental roles in bone remodeling and skeletal health. Much effort has been focused on identifying the regulators of osteoclast metabolism. Noncoding RNAs (ncRNAs) reportedly regulate osteoclast formation, differentiation, survival, and bone-resorbing activity to participate in bone physiology and pathology. The present review intends to provide a general framework for how ncRNAs and their targets regulate osteoclast differentiation and the important events of osteoclastogenesis they are involved in, including osteoclast precursor generation, early differentiation, mononuclear osteoclast fusion, and multinucleated osteoclast function and survival. This framework is beneficial for understanding bone biology and for identifying the potential biomarkers or therapeutic targets of bone diseases. The review also summarizes the results of in vivo experiments and classic experiment methods for osteoclast-related researches.

Small and Long Non-coding RNAs as Functional Regulators of Bone Homeostasis, Acting Alone or Cooperatively

Emerging knowledge indicates that non-coding RNAs, including microRNAs (miRNAs) and long-noncoding RNAs (lncRNAs), have a pivotal role in bone development and the pathogenesis of bone-related disorders. Most recently, miRNAs have started to be regarded as potential biomarkers or targets for various sets of diseases, while lncRNAs have gained attention as a new layer of gene expression control acting through versatile interactions, also with miRNAs. The rapid development of RNA sequencing techniques based on next-generation sequencing (NGS) gives us better insight into molecular pathways regulated by the miRNA-lncRNA network. In this review, we summarize the current knowledge related to the function of miRNAs and lncRNAs as regulators of genes that are crucial for proper bone metabolism and homeostasis. We have characterized important non-coding RNAs and their expression signatures, in relationship to bone. Analysis of the biological function of miRNAs and lncRNAs, as well as their network, will pave the way for a better understanding of the pathogenesis of various bone disorders. We also think that this knowledge may lead to the development of innovative diagnostic tools and therapeutic approaches for bone-related disorders.

Identification and expression analysis of microRNAs in tibial growth plate of chicken through thiram toxicity

Thiram is a widely known tibial dyschondroplasia (TD) inducer. TD, a common metabolic cartilage disease, presents in rapidly growing poultry birds. There are evidences that miRNAs are involved in diverse aspects of normal skeletal development, but very less is known about the role of miRNAs in TD. Therefore, this study aimed to determine which genes and pathways show differential expression between TD suffered chickens and normal chickens. We collected growth plates from ten-days-old TD chickens and control chickens and performed high-throughput RNA sequencing (RNA-Seq). Afterwards, target prediction, GO annotation and KEGG pathway analysis were carried out to understand the role of DEMs (differentially expressed microRNAs). We obtained 96,884,760 and 94,574,290 clean reads and identified 17 significant DEMs between the TD and control groups. Functional enrichment analysis of DEMs indicated that the putative targets of miRNAs were remarkably enriched in bone-related pathways, such as Notch, MAPK and Autophagy. Overall, this study provides detailed understanding about the pathogenesis of thiram induced TD and new insights towards the molecular mechanism of miRNAs.

Physical Exercise Modulates miR-21-5p, miR-129-5p, miR-378-5p, and miR-188-5p Expression in Progenitor Cells Promoting Osteogenesis

Physical exercise is known to promote beneficial effects on overall health, counteracting risks related to degenerative diseases. MicroRNAs (miRNAs), short non-coding RNAs affecting the expression of a cell’s transcriptome, can be modulated by different stimuli. Yet, the molecular effects on osteogenic differentiation triggered by miRNAs upon physical exercise are not completely understood. In this study, we recruited 20 male amateur runners participating in a half marathon. Runners’ sera, collected before (PRE RUN) and after (POST RUN) the run, were added to cultured human mesenchymal stromal cells. We then investigated their effects on the modulation of selected miRNAs and the consequential effects on osteogenic differentiation. Our results showed an increased expression of miRNAs promoting osteogenic differentiation (miR-21-5p, miR-129-5p, and miR-378-5p) and a reduced expression of miRNAs involved in the adipogenic differentiation of progenitor cells (miR-188-5p). In addition, we observed the downregulation of PTEN and SMAD7 expression along with increased AKT/pAKT and SMAD4 protein levels in MSCs treated with POST RUN sera. The consequent upregulation of RUNX2 expression was also proven, highlighting the molecular mechanisms by which miR-21-5p promotes osteogenic differentiation. In conclusion, our work proposes novel data, which demonstrate how miRNAs may regulate the osteogenic commitment of progenitor cells in response to physical exercise.

Identification of differentially expressed microRNAs in the bone marrow of osteoporosis patients

This study aimed to identify specific microRNAs (miRNAs) related to postmenopausal osteoporosis (OP) in human. A total of 67 conserved miRNAs, including 50 miRNAs significantly up-regulated and 17 miRNAs significantly downregulated, showed differential expression between OP group and control group. 180 hairpin structures were predicted and 199 potential novel miRNA candidates with 18 to 25 nt in length, which will greatly enrich the human miRBase. 4 miRNAs (miR-518b, miR-582-3p, miR-148a-3p and miRNA-223-3p) had upregulated expression and 4 (miR-7d-5p, miR-210-3p, miR-324-5p and miR-654-3p) showed down-regulated expression. Target genes of these miRNAs were involved in bone development, cell proliferation in bone marrow, osteoblast development, negative regulation of osteoblast differentiation, and negative regulation of osteoclast development, as well as several osteogenesis related pathways. Canonical Wnt signaling pathway was selected for verification and function analysis. The expression of Wnt1, FZD10, LRP5, DVL2 and LEF1 was down-regulated significantly, while that of SFRP1, DKK1, and CHD8 was up-regulated markedly. In conclusion, these genes play important roles in OP, which improves our understanding of pathogenesis of OP.

miR-338-3p regulates osteoclastogenesis via targeting IKKβ gene

This study determined the effects of miR-338-3p on osteoclast (OC) differentiation and activation. The change levels of miR-338-3p in differentiated OCs were investigated by microRNA microarray assay and quantitative real-time PCR analysis. The effects of miR-338-3p on the differentiation and activation of OCs were determined by tartrate-resistant acid phosphatase staining resorption activity assay and Western blot. Target genes of miR-338-3p were identified by target gene prediction and dual-luciferase reporter gene detection assay as well as Western blot. Results showed that miR-338-3p was markedly downregulated in differentiated OCs. miR-338-3p could inhibit the formation and absorption activity of OCs. Western blot showed that miR-338-3p could influence the change levels of OC differentiation-related proteins. Dual-luciferase reporter gene detection assay and Western blot both showed that miR-338-3p directly targeted IKKβ gene. In conclusion, miR-338-3p may affect the formation and activity of OCs by targeting the IKKβ gene.

miRNA-seq analysis of human vertebrae provides insight into the mechanism underlying GIOP

High-throughput sequencing (HTS) was recently applied to detect microRNA (miRNA) regulation in age-related osteoporosis. However, miRNA regulation has not been reported in glucocorticoid-induced osteoporosis (GIOP) patients and the mechanism of GIOP remains elusive. To comprehensively analyze the role of miRNA regulation in GIOP based on human vertebrae and to explore the molecular mechanism, a high-throughput sequencing strategy was employed to identify miRNAs involved in GIOP. Twenty-six patients undergoing spinal surgery were included in this study. Six vertebral samples were selected for miRNA sequencing (miRNA-seq) analysis and 26 vertebral samples were verified by qRT-PCR. Bioinformatics was utilized for target prediction, to investigate the regulation of miRNA-mRNA networks, and Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses. Six significantly up-regulated miRNAs (including one novel miRNA) and three significantly down-regulated miRNAs were verified via miRNA-seq and verified in the vertebrae of GIOP patients. Up-regulated miRNAs included hsa-miR-214-5p, hsa-miR-10b-5p, hsa-miR-21-5p, hsa-miR-451a, hsa-miR-186-5p, and hsa-miR-novel-chr3_49,413 while down-regulated miRNAs included hsa-let-7f-5p, hsa-let-7a-5p, and hsa-miR-27a-3p. Bioinformatics analysis revealed 5983 and 23,463 predicted targets in the up-regulated and down-regulated miRNAs respectively, using the miRanda, miRBase and TargetScan databases. The target genes of these significantly altered miRNAs were enriched to 1939 GO terms and 84 KEGG pathways. GO terms revealed that up-regulated targets were most enriched in actin filament-based processes (BP), anchoring junction (CC), and cytoskeletal protein binding (MF). Conversely, the down-regulated targets were mostly enriched in multicellular organismal development (BP), intracellular membrane-bounded organelles (CC), and protein binding (MF). Top-10 pathway analysis revealed that the differentially expressed miRNAs in GIOP were closely related to bone metabolism-related pathways such as FoxO, PI3K-Akt, MAPK and Notch signaling pathway. These results suggest that significantly altered miRNAs may play an important role in GIOP by targeting mRNA and regulating biological processes and bone metabolism-related pathways such as MAPK, FoxO, PI3K-Akt and Notch signaling, which provides novel insight into the mechanism of GIOP and lays a good foundation for the prevention and treatment of GIOP.

Clinical case report of patients with osteosarcoma and anticancer benefit of calycosin against human osteosarcoma cells

Osteosarcoma (OS) is a malignant neoplasia in bone, characterized with main occurrence in teenagers. Calycosin (CC), a bioactive compound, is found to play potent pharmacological effects against cancer. Our previous study indicates CC-exerted benefits for anti-OS effect. However, further molecular mechanism behind this action needs to be investigated. In this study, human OS samples and clinical data were collected and used for further test and analysis. In addition, human osteosarcoma cell line (143B) and tumor-xenograft nude mice were used to evaluate antineoplastic activities of CC through a series of biochemical methods and immunoassays, respectively. Compared with non-OS controls, human OS samples showed increased levels of neoplastic microRNA-223 (miR-223), and elevated expressions of NF-κBp65, IκBα proteins in tumor cells. In cell culture study, CC-treated 143B cells showed reduced cell growth, increased lactic dehydrogenase (LD) content, and downregulated cellular miR-223 level. Immunolabeled cells of proliferating cell nuclear antigen, B-cell lymphoma 2 (Bcl-2), poly(ADP-ribose) polymerase (PARP) in CC treatments were decreased dose-dependently, while caspase-3 positive cells were elevated. Further, protein expressions of NF-κBp65, IκBα in CC-treated cells were downregulated. In addition, tumor-xenograft nude mice followed by CC treatments exhibited reductions of tumor mass, miR-223 levels, and Bcl-2, PARP-positive cells, as well as downregulations of NF-κBp65, IκBα protein expressions in OS samples. Taken together, these experimental findings reveal that CC exhibits potential pharmacological activities against OS through inducing apoptosis and inhibiting miR-223-IκBα signaling pathway in neoplastic cells.

MicroRNA‑223 promotes osteoblast differentiation of MC3T3‑E1 cells by targeting histone deacetylase 2

MicroRNAs (miRNAs) have emerged as pivotal regulators in various physiological and pathological processes at the post‑transcriptional level, and may serve important roles in osteogenic differentiation. However, their roles and functions are not fully understood. In the present study, miR‑223‑5p was identified as a modulator of osteoblastic differentiation in MC3T3‑E1 cells. Reverse transcription‑quantitative polymerase chain reaction and western blotting demonstrated that miR‑223‑5p was significantly upregulated in MC3T3‑E1 cells following the induction of osteoblast differentiation. Overexpression of miR‑223‑5p promoted osteogenic differentiation both in vitro and vivo. Expression of histone deacetylase 2 (HDAC2), which acts as a negative regulator of osteogenesis, was regulated by miR‑223‑5p. Collectively, the results of the present study revealed a novel miR‑223‑5p/HDAC2 axis that regulates osteoblast differentiation, and may serve as a potential target for enhancing bone formation in vivo.

Inflammation-induced overexpression of microRNA-223-3p regulates odontoblastic differentiation of human dental pulp stem cells by targeting SMAD3

AIM

To profile miRNA expression between inflamed and healthy human dental pulp tissues and to investigate how the upregulation of miR-223-3p in the inflamed pulp tissue regulates odontoblast differentiation and regeneration.

METHODOLOGY

Microarray analysis was used to identify differences in miRNA expression patterns between healthy and inflamed pulp tissue. The results were validated using quantitative real-time PCR. To determine the effect of miR-223-3p on odontoblast differentiation, miR-223-3p was overexpressed in human dental pulp stem cells (DPSCs), which were cultured in mineralizing induction medium (to induce odontoblast differentiation). To identify the target genes of miR-223-3p, an SABiosciences Human Osteogenesis PCR Array, combined with bioinformatics, was used. Furthermore, a dual-luciferase reporter assay and a small interfering RNA (siRNA) experiment were used to confirm the relationship between miR-223-3p and its target gene. Statistical analysis was performed using the Student's t-test or one-way analysis of variance (anova); P < 0.05 was considered statistically significant.

RESULTS

Seventy-nine miRNAs were significantly differentially expressed (fold change >2.0; P < 0.05) between the two tissues. In particular, miR-223-3p was markedly upregulated in inflamed dental pulp. Overexpression of miR-223-3p in DPSCs significantly increased the protein levels of dentine sialophosphoprotein (DSPP) and dentine matrix protein 1 (DMP-1) (P < 0.05). However, the SMAD family member 3 (SMAD3) protein level was significantly lower than in control DPSCs (P < 0.05). Bioinformatics and the dual-luciferase assay reporter assay indicated that Smad3 was a potential target of miR-223-3p. Knockdown of Smad3 in DPSCs subjected to mineralization induction resulted in detection of DSPP and DMP-1 earlier than in control DPSCs, and it increased the protein level of alkaline phosphatase (ALP), thereby promoting odontoblast differentiation.

CONCLUSIONS

miR-223-3p is implicated in the regulation of odontoblast differentiation, which may be involved in the process of pulpitis repair.

Altered MicroRNA Profile in Osteoporosis Caused by Impaired WNT Signaling

CONTEXT

WNT signaling is fundamental to bone health, and its aberrant activation leads to skeletal pathologies. The heterozygous missense mutation p.C218G in WNT1, a key WNT pathway ligand, leads to severe early-onset and progressive osteoporosis with multiple peripheral and spinal fractures. Despite the severe skeletal manifestations, conventional bone turnover markers are normal in mutation-positive patients.

OBJECTIVE

This study sought to explore the circulating microRNA (miRNA) pattern in patients with impaired WNT signaling.

DESIGN AND SETTING

A cross-sectional cohort study at a university hospital.

PARTICIPANTS

Altogether, 12 mutation-positive (MP) subjects (median age, 39 years; range, 11 to 76 years) and 12 mutation-negative (MN) subjects (35 years; range, 9 to 59 years) from two Finnish families with WNT1 osteoporosis due to the heterozygous p.C218G WNT1 mutation.

METHODS AND MAIN OUTCOME MEASURE

Serum samples were screened for 192 miRNAs using quantitative polymerase chain reaction. Findings were compared between WNT1 MP and MN subjects.

RESULTS

The pattern of circulating miRNAs was significantly different in the MP subjects compared with the MN subjects, with two upregulated (miR-18a-3p and miR-223-3p) and six downregulated miRNAs (miR-22-3p, miR-31-5p, miR-34a-5p, miR-143-5p, miR-423-5p, and miR-423-3p). Three of these (miR-22-3p, miR-34a-5p, and miR-31-5p) are known inhibitors of WNT signaling: miR-22-3p and miR-34a-5p target WNT1 messenger RNA, and miR-31-5p is predicted to bind to WNT1 3'UTR.

CONCLUSIONS

The circulating miRNA pattern reflects WNT1 mutation status. The findings suggest that the WNT1 mutation disrupts feedback regulation between these miRNAs and WNT1, providing insights into the pathogenesis of WNT-related bone disorders. These miRNAs may have potential in the diagnosis and treatment of osteoporosis.

Association between circulating miRNAs and spinal involvement in patients with axial spondyloarthritis

OBJECTIVES

Dysregulation of miRNAs and their target genes contributes to the pathophysiology of autoimmune diseases. Circulating miRNAs may serve as diagnostic/prognostic biomarkers. We aimed to investigate the association between circulating miRNAs, disease activity and spinal involvement in patients with axial spondyloarthritis (AxSpA).

METHODS

Total RNA was isolated from the plasma of patients with non-radiographic (nr)AxSpA, patients with ankylosing spondylitis (AS) and healthy controls (HC) via phenol-chloroform extraction. A total of 760 miRNAs were analysed with TaqMan® Low Density Arrays, and the expression of 21 miRNAs was assessed using single assays.

RESULTS

Comprehensive analysis demonstrated the differential expression of miRNAs among patients with progressive spinal disease. Of the 21 miRNAs selected according to their expression patterns, the levels of miR-625-3p were significantly different between nr-AxSpA patients and HCs. We found no correlation between miRNA levels and Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) in nr-AxSpA patients. Selected miRNAs, such as miR-29a-3p, miR-146a-5p or miR-222-3p with an established role in extracellular matrix formation and inflammation were associated with spinal changes and/or disease activity assessed by BASDAI in AS patients, including miR-625-3p reflecting disease activity in AS with spinal involvement.

CONCLUSIONS

Our data indicate that circulating miRNAs play a role in the pathogenesis of AxSpA and are also suggestive of their potential as biomarkers of disease progression. We hypothesize that differential systemic levels of miRNA expression reflect miRNA dysregulation at sites of spinal inflammation or bone formation where these molecules contribute to the development of pathophysiological features typical of AxSpA.

Expression profiling of microRNAs in human bone tissue from postmenopausal women

Bone tissue is composed of several cell types, which express their own microRNAs (miRNAs) that will play a role in cell function. The set of total miRNAs expressed in all cell types configures the specific signature of the bone tissue in one physiological condition. The aim of this study was to explore the miRNA expression profile of bone tissue from postmenopausal women. Tissue was obtained from trabecular bone and was analyzed in fresh conditions (n = 6). Primary osteoblasts were also obtained from trabecular bone (n = 4) and human osteoclasts were obtained from monocyte precursors after in vitro differentiation (n = 5). MicroRNA expression profiling was obtained for each sample by microarray and a global miRNA analysis was performed combining the data acquired in all the microarray experiments. From the 641 miRNAs detected in bone tissue samples, 346 (54%) were present in osteoblasts and/or osteoclasts. The other 46% were not identified in any of the bone cells analyzed. Intersection of osteoblast and osteoclast arrays identified 101 miRNAs shared by both cell types, which accounts for 30-40% of miRNAs detected in these cells. In osteoblasts, 266 miRNAs were detected, of which 243 (91%) were also present in the total bone array, representing 38% of all bone miRNAs. In osteoclasts, 340 miRNAs were detected, of which 196 (58%) were also present in the bone tissue array, representing 31% of all miRNAs detected in total bone. These analyses provide an overview of miRNAs expressed in bone tissue, broadening our knowledge in the microRNA field.

miRNA biogenesis-associated RNase III nucleases Drosha and Dicer are upregulated in colorectal adenocarcinoma

Drosha and Dicer are important regulators of microRNA (miRNA) biogenesis, and it has been suggested that their aberrant regulation may cause colorectal cancer (CRC). The aim of the present study was to evaluate the mRNA expression levels of these two important RNase III nucleases and their association with clinical features in CRC specimens from South Korean patients. The expression levels of Drosha and Dicer mRNA were investigated in 77 CRC tissues and adjacent histologically non-neoplastic tissues using the quantitative polymerase chain reaction. The expression levels of Drosha and Dicer mRNA were identified to be upregulated in CRC. Neither the Drosha nor the Dicer mRNA expression level was associated with any clinical parameter, including sex, age, TNM stage, body mass index and carcinoembryonic antigen titer in patients with CRC. Furthermore, the expression levels of Drosha and Dicer mRNA were not associated with each other. The miRNA biogenesis-associated RNase III nucleases Drosha and Dicer are significantly upregulated in CRC, suggesting their importance in the pathobiology of colorectal carcinogenesis.

MicroRNA-221 is involved in the regulation of osteoporosis through regulates RUNX2 protein expression and osteoblast differentiation

INTRODUCTION

MicroRNAs (miRNAs) has emerged as important factors in osteogenesis and chondrogenesis. This study aimed to determine whether miR-221 is involved in the regulation of osteoporosis and its underlying mechanism.

METHODS

Total RNA was extracted from fresh femoral neck trabecular bone from women undergoing hip replacement due to either osteoporotic fracture (OP group, n = 12) or osteoarthritis in the absence of osteoporosis (Control group, n = 12). Gene expression was quantified using TaqMan quantitative RT-PCR assays and protein production was determined by western blot analysis. The role of miR-221 in osteoblast differentiation was identified by gain or loss function experiment. MiRNA targets were identified using bioinformatics and luciferase reporter assay.

RESULTS

MiR-221 was down-regulated in the osteoporotic samples compared with non-osteoporotic controls, and decreased in a C2C12 cell model of osteogenic differentiation. Overexpression of miR-221 resulted in a decrease in the osteogenic potential, as indicated by the reduced expression levels of key osteoblast markers, including osteocalcin (OC), alkaline phosphatase (ALP) and collagen, type I, α 1 (COL1A1), whereas inhibition of miR-221 promoted the activity of OC, ALP and COL1A1. Then bioinformatic analysis identified potential target sites of the miR-221 located in the 3' untranslated regions of RUNX2. Western blot analysis demonstrated that miR-221 inhibited RUNX2 gene expression. Furthermore, dual-luciferase reporter assays confirmed that RUNX2 was a direct target of miR-221. Rescue experiments showed that overexpression of RUNX2 significantly attenuated the effect of miR-221 on osteoblast markers providing strong evidence that miR-221 mediated the osteoblast differentiation by targeting RUNX2.

CONCLUSIONS

Taken together, these data implied that miR-221 played an important part in osteoporosis through regulating RUNX2 expression and osteoblast differentiation.

MicroRNAs and Periodontal Homeostasis

MicroRNAs (miRNAs) are a group of small RNAs that control gene expression in all aspects of eukaryotic life, primarily through RNA silencing mechanisms. The purpose of the present review is to introduce key miRNAs involved in periodontal homeostasis, summarize the mechanisms by which they affect downstream genes and tissues, and provide an introduction into the therapeutic potential of periodontal miRNAs. In general, miRNAs function synergistically to fine-tune the regulation of biological processes and to remove expression noise rather than by causing drastic changes in expression levels. In the periodontium, miRNAs play key roles in development and periodontal homeostasis and during the loss of periodontal tissue integrity as a result of periodontal disease. As part of the anabolic phase of periodontal homeostasis and periodontal development, miRNAs direct periodontal fibroblasts toward alveolar bone lineage differentiation and new bone formation through WNT, bone morphogenetic protein, and Notch signaling pathways. miRNAs contribute equally to the catabolic aspect of periodontal homeostasis as they affect osteoclastogenesis and osteoclast function, either by directly promoting osteoclast activity or by inhibiting osteoclast signaling intermediaries or through negative feedback loops. Their small size and ability to target multiple regulatory networks of related sets of genes have predisposed miRNAs to become ideal candidates for drug delivery and tissue regeneration. To address the immense therapeutic potential of miRNAs and their antagomirs, an ever growing number of delivery approaches toward clinical applications have been developed, including nanoparticle carriers and secondary structure interference inhibitor systems. However, only a fraction of the miRNAs involved in periodontal health and disease are known today. It is anticipated that continued research will lead to a more comprehensive understanding of the periodontal miRNA world, and a systematic effort toward harnessing the enormous therapeutic potential of these small molecules will greatly benefit the future of periodontal patient care.

microRNAs in the pathophysiology of CKD-MBD: Biomarkers and innovative drugs

microRNAs comprise a novel class of endogenous small non-coding RNAs that have been shown to be implicated in both vascular damage and bone pathophysiology. Chronic kidney disease-mineral bone disorder (CKD-MBD) is characterized by vessel and bone damage secondary to progressive loss of kidney function. In this review, we will describe how several microRNAs have been implicated, in recent years, in cellular and animal models of CKD-MBD, and have been very recently shown to be deregulated in patients with CKD. Particular emphasis has been placed on the endothelial-specific miR-126, a potential biomarker of endothelial dysfunction, and miR-155 and miR-223, which play a role in both vascular smooth muscle cells and osteoclasts, with an impact on the vascular calcification and osteoporosis process. Finally, as these microRNAs may constitute useful targets to prevent or treat complications of CKD-MBD, we will discuss their potential as innovative drugs, describe how they could be delivered in a timely and specific way to vessels and bone by using the most recent techniques such as nanotechnology, viral vectors or CRISPR gene targeting.

Role of Osterix and MicroRNAs in Bone Formation and Tooth Development

Osterix (Osx) is an osteoblast-specific transcription factor that is essential for bone formation. MicroRNAs (miRNAs) are ~22-nucleotide-long noncoding RNAs that play important regulatory roles in animals and plants by targeting mRNAs for cleavage or translational repression. They can also control osteoblast-mediated bone formation and osteoclast-related bone remodeling. The vital roles of Osx and miRNAs during bone formation have been well studied, but very few studies have discussed their co-functions and the relationships between them. In this review, we outline the significant functions of Osx and miRNAs on certain cell types during osteogenesis and illustrate their roles during tooth development. More importantly, we discuss the relationship between Osx and miRNAs, which we believe could lead to a new treatment for skeletal and periodontal diseases.

The Regulatory Roles of MicroRNAs in Bone Remodeling and Perspectives as Biomarkers in Osteoporosis

MicroRNAs are involved in many cellular and molecular activities and played important roles in many biological and pathological processes, such as tissue formation, cancer development, diabetes, neurodegenerative diseases, and cardiovascular diseases. Recently, it has been reported that microRNAs can modulate the differentiation and activities of osteoblasts and osteoclasts, the key cells that are involved in bone remodeling process. Meanwhile, the results from our and other research groups showed that the expression profiles of microRNAs in the serum and bone tissues are significantly different in postmenopausal women with or without fractures compared to the control. Therefore, it can be postulated that microRNAs might play important roles in bone remodeling and that they are very likely to be involved in the pathological process of postmenopausal osteoporosis. In this review, we will present the updated research on the regulatory roles of microRNAs in osteoblasts and osteoclasts and the expression profiles of microRNAs in osteoporosis and osteoporotic fracture patients. The perspective of serum microRNAs as novel biomarkers in bone loss disorders such as osteoporosis has also been discussed.