MicroRNA-338-3p inhibits glucocorticoid-induced osteoclast formation through RANKL targeting

Therapeutic effects of resveratrol on epigenetic mechanisms in age-related diseases: A comprehensive review

Recently, various studies have shown that epigenetic changes are associated with aging and age-related diseases. Both animal and human models have revealed that epigenetic processes are involved in aging mechanisms. These processes happen at multiple levels and include histone modification, DNA methylation, and changes in noncoding RNA expression. Consequently, changes in the organization of chromatin and DNA accessibility lead to the regulation of gene expression. With increasing awareness of the pivotal function of epigenetics in the aging process, researchers' attention has been drawn to how these epigenetic changes can be modified to prevent, stop, or reverse aging, senescence, and age-related diseases. Among various agents that can affect epigenetic, polyphenols are well-known phytochemicals found in fruits, vegetables, and plants. Polyphenols are found to modify epigenetic-related mechanisms in various diseases and conditions, such as metabolic disorders, obesity, neurodegenerative diseases, cancer, and cardiovascular diseases. Resveratrol (RSV) is a member of the stilbene subgroup of polyphenols which is derived from various plants, such as grapes, apples, and blueberries. Therefore, herein, we aim to summarize how RSV affects different epigenetic processes to change aging-related mechanisms. Furthermore, we discuss its roles in age-related diseases, such as Alzheimer's, Parkinson's, osteoporosis, and cardiovascular diseases.

MicroRNA‑338‑3p regulates age‑associated osteoporosis via targeting PCSK5

Bone loss is a disease that is highly associated with aging. This deleterious health condition has become a public concern worldwide, and there is an urgent need to discover more novel therapeutic strategies for the development of age‑associated osteoporosis. The present study aimed to explore the association between proprotein convertase subtilisin/kexin type 5 (PCSK5) and microRNA(miR)‑338‑3p in bone‑formation and bone‑loss processes. Western blotting assay and reverse transcription‑quantitative PCR were employed to analyze PCSK5 and miR‑338‑3p expression levels in bone mesenchymal stem cells (BMSCs). Dual‑luciferase reporter and RNA pull‑down assays were used to determine the target. For osteoblastic differentiation verification, alkaline phosphatase activity, osteocalcin secretion detection, bone formation‑related indicators (osterix, runt‑related gene 2, osteopontin and bone sialoprotein), hematoxylin and eosin staining and Alizarin Red S staining were performed. The findings of the present study indicated that the expression level of PCSK5 was higher in BMSCs from young rat samples, whereas the expression level of miR‑338‑3p was higher in BMSCs from samples of old rats. Experimental results also revealed that unlike miR‑338‑3p, downregulation of PCSK5 inhibited osteoblastic differentiation and osteogenesis by inhibiting alkaline phosphatase, osteocalcin, osterix, runt‑related transcription factor 2, osteopontin, bone sialoprotein and mineralized nodule formation. Overall, the results suggested that miR‑338‑3p could suppress age‑associated osteoporosis by regulating PCSK5.

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.

Serum Profile of microRNAs Linked to Bone Metabolism During Sequential Treatment for Postmenopausal Osteoporosis

CONTEXT

Serum expression of microRNAs (miRs) related to bone metabolism is affected by antiosteoporotic treatment.

OBJECTIVE

To investigate the effect of sequential treatments on miR expression in postmenopausal women with osteoporosis.

DESIGN

Observational, open label, nonrandomized clinical trial.

SETTING

A single-center outpatient clinic.

PATIENTS AND INTERVENTIONS

Denosumab (Dmab) was administered for 12 months in 37 women who were treatment-naïve (naïve group) (n = 11) or previously treated with teriparatide (TPTD group) (n = 20) or zoledronate (ZOL group) (n = 6).

MAIN OUTCOME MEASURES

Relative serum expression of miRs linked to bone metabolism at 3 and 6 months of Dmab treatment.

RESULTS

Baseline relative expression of miR-21a-5p, miR-23a-3p, miR-29a-3p, and miR-338-3p was higher in the TPTD group, while the relative expression of miR-21a-5p was lower in the ZOL group compared to the naïve group. Dmab decreased the relative expression of miR-21a-5p at 3 months (fold change [FC] 0.43, P < 0.001) and 6 months (FC 0.34, P < 0.001), and miR-338-3p and miR-2861 at 6 months (FC 0.31, P = 0.041; FC 0.52, P = 0.016, respectively) in the whole cohort. In subgroup analyses, Dmab decreased the relative expression of miR-21a-5p, miR-29a-3p, miR-338-3p, and miR-2861 at 3 months (FC 0.13, P < 0.001; FC 0.68, P = 0.044; FC 0.46, P = 0.012; and FC 0.16, P < 0.001, respectively) and 6 months (FC 0.1, P < 0.001; FC 0.52, P < 0.001; FC 0.04, P = 0.006; and FC 0.2, P < 0.001, respectively) only within the TPTD group.

CONCLUSIONS

TPTD treatment potentially affects the expression of the pro-osteoclastogenic miR-21a-5p and miRs related to the expression of osteoblastic genes RUNX2 (miR23a-3p), COL1 (miR-29a-3p), and HDAC5 (miR-2861), while sequential treatment with Dmab acts in the opposite direction.

miR-101-3p/Rap1b signal pathway plays a key role in osteoclast differentiation after treatment with bisphosphonates

Bisphosphonates are the mainstay of therapy worldwide for osteoporosis. However, bisphosphonates also have limitations. The objective of this study was to determine the role of miR-101-3p/Rap1b signal pathway in osteoclast differentiation after treatment with bisphosphonates. Our results revealed that miR-101-3p was an important regulator in bisphosphonates treated-osteoclasts. When miR-101-3p was down-regulated in bone marrow-derived macrophage-like cells (BMMs), the development of mature osteoclasts was promoted, and vice versa. However, alendronate decreased multinucleated cell number regardless of whether miR-101-3p was knocked down or over-expressed. TRAP activity assay confirmed the above results. Luciferase assay indicated that miR-101-3p was a negative regulator of Rap1b. Western blot analysis revealed that protein expression level of Rap1b in BMMs transfected with OV-miR-101-3p was lower than that in BMMs transfected with an empty vector. Rap1b overexpression increased TRAP-positive multinucleated cells, while Rap1b inhibition decreased the cell numbers. In vivo data showed that miR-101-3p inhibited osteoclast differentiation in ovariectomized mice while overexpressed of Rap1b blocked the differentiation. Taken together, our data demonstrate that miR-101-3p/Rap1b signal pathway plays a key role in osteoclast differentiation after treatment with bisphosphonates.

Scaffold-Based Gene Therapeutics for Osteochondral Tissue Engineering

Significant progress in osteochondral tissue engineering has been made for biomaterials designed to deliver growth factors that promote tissue regeneration. However, due to diffusion characteristics of hydrogels, the accurate delivery of signaling molecules remains a challenge. In comparison to the direct delivery of growth factors, gene therapy can overcome these challenges by allowing the simultaneous delivery of growth factors and transcription factors, thereby enhancing the multifactorial processes of tissue formation. Scaffold-based gene therapy provides a promising approach for tissue engineering through transfecting cells to enhance the sustained expression of the protein of interest or through silencing target genes associated with bone and joint disease. Reports of the efficacy of gene therapy to regenerate bone/cartilage tissue regeneration are widespread, but reviews on osteochondral tissue engineering using scaffold-based gene therapy are sparse. Herein, we review the recent advances in gene therapy with a focus on tissue engineering scaffolds for osteochondral regeneration.

MiRNA-483-5p is involved in the pathogenesis of osteoporosis by promoting osteoclast differentiation

AIMS

The study aimed to investigate the roles of miR-483-5p and IGF2 in osteoclast formation.

METHODS

Blood and bone tissues were collected from osteoporosis and non-osteoporosis patients with hip fractures for gene expression analysis. CD14 + peripheral blood mononuclear cells (PBMCs) were isolated for differentiating osteoclasts. MiR-483-5p mimic and inhibitor was transfected into CD14 + PBMCs, respectively. Predicted by TargetScan and verified by Dual-luciferase reporter assay system, insulin-like growth factor-2 (IGF2) could be targeted by miR-483-5p. IGF2 expression vector was co-transfected with miR-483-5p mimic to study the role of IGF2 in miR-483-5p affecting osteoclast differentiation. Flow cytometry was performed for cell apoptosis analysis.

RESULTS

High-expressed miR-483-5p and low-expressed IGF2 were frequently found in the serums and bone tissues derived from osteoporotic patients. We found that up-regulation of miR-483-5p in CD14 + PBMCs notably increased the number of TRAP-positive cells, at the same time, the expression levels of TRAP, nuclear factor of activated T-cells (NFATc1), cytoplasmic 1 (NFAT2) and Cathepsin K (CTSK) were also up-regulated. However, overexpressed IGF2 effectively reversed such effects produced by up-regulation of miR-483-5p on osteoclastogenesis-related factors in CD14 + PBMCs. Moreover, forced expression of IGF2 could also enhance apoptosis of osteoclasts reduced by miR-483-5p.

CONCLUSIONS

Our study suggests that miRNA-483-5p is involved in the pathogenesis of osteoporosis by promoting osteoclast differentiation.

miRNA-26a-5p Accelerates Healing via Downregulation of PTEN in Fracture Patients with Traumatic Brain Injury

Patients who sustain a traumatic brain injury (TBI) are known to have a significantly quicker fracture healing time than patients with isolated fractures, but the underlying mechanism has yet to be identified. In this study, we found that the upregulation of miRNA-26a-5p induced by TBI correlated with a decrease in phosphatase and tensin homolog (PTEN) in callus formation. In vitro, overexpressing miRNA-26a-5p inhibited PTEN expression and accelerated osteoblast differentiation, whereas silencing of miRNA-26a-5p inhibited osteoblast activity. Reduction of PTEN facilitated osteoblast differentiation via the PI3K/AKT signaling pathway. Through luciferase assays, we found evidence that PTEN is a miRNA-26a-5p target gene that negatively regulates the differentiation of osteoblasts. Moreover, the present study confirmed that preinjection of agomiR-26a-5p leads to increased bone formation. Collectively, these results indicate that miRNA-26a-5p overexpression may be a key factor governing the improved fracture healing observed in TBI patients after the downregulation of PTEN and PI3K/AKT signaling. Upregulation of miRNA-26a-5p may therefore be a promising therapeutic strategy for promoting fracture healing.

Deregulated miRNAs in bone health: Epigenetic roles in osteoporosis

MicroRNA (miRNA) has shown to enhance or inhibit cell proliferation, differentiation and activity of different cell types in bone tissue. The discovery of miRNA actions and their targets has helped to identify them as novel regulations actors in bone. Various studies have shown that miRNA deregulation mediates the progression of bone-related pathologies, such as osteoporosis. The present review intends to give an exhaustive overview of miRNAs with experimentally validated targets involved in bone homeostasis and highlight their possible role in osteoporosis development. Moreover, the review analyzes miRNAs identified in clinical trials and involved in osteoporosis.

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.

Silk Biomaterials-Mediated miRNA Functionalized Orthopedic Devices

Silk-based bioresorbable medical devices, such as screws, plates, and rods, have been under investigation due to their promising properties for orthopedic repairs. Options to functionalize these new devices for enhanced control of bone regeneration would also exploit the compatible processing methods used to generate the devices. MicroRNAs are important regulators of bone maintenance and formation, and miRNA-based therapeutics have the potential to aid bone repair, utilizing a transient therapeutic approach with local bioactivity. We hypothesized that silk-based orthopedic devices could be used for the local delivery of miRNAs, using anti-sense miR-214 (AS-miR-214), to inhibit endogenous expression of osteoinductive antagonist and thereby supporting the upregulation of osteoinductive target molecules activating transcription factor 4 (ATF4) and Osterix (Osx). AS-miR-214 silk devices, prepared using surface coating, demonstrated continuous release of miRNA inhibitors up to 7 days in vitro. Additionally, human mesenchymal stem cells seeded on AS-miR-214 silk films expressed higher levels of osteogenic genes ATF4, Osx, Runx2, and Osteocalcin. Interestingly, these cells exhibited lower cell viability and DNA content over 21 days. Conversely, the cells demonstrated significantly higher levels of alkaline phosphatase expression and calcium deposition compared with cells seeded on silk films with nontargeting miRNA controls. The study demonstrated that the silk-based orthopedic devices, in conjunction with bioactive miRNA-based therapeutics, may serve as a novel system for localized bone tissue engineering, enhancing osteogenesis at the implant interface while avoiding detrimental systematic side effects.

The emerging role of microRNAs in bone remodeling and its therapeutic implications for osteoporosis

Osteoporosis, a common and multifactorial disease, is influenced by genetic factors and environments. However, the pathogenesis of osteoporosis has not been fully elucidated yet. Recently, emerging evidence suggests that epigenetic modifications may be the underlying mechanisms that link genetic and environmental factors with increased risks of osteoporosis and bone fracture. MicroRNA (miRNA), a major category of small noncoding RNA with 20–22 bases in length, is recognized as one important epigenetic modification. It can mediate post-transcriptional regulation of target genes with cell differentiation and apoptosis. In this review, we aimed to profile the role of miRNA in bone remodeling and its therapeutic implications for osteoporosis. A deeper insight into the role of miRNA in bone remodeling and osteoporosis can provide unique opportunities to develop a novel diagnostic and therapeutic approach of osteoporosis.

Regulation of Bone Metabolism by microRNAs

PURPOSE OF REVIEW

The small non-coding microRNAs (miRNAs) have emerged as important post-transcriptional regulators of various physiological and pathological processes. The purpose of this article is to review the important recent advances on the role of miRNAs in bone remodeling and metabolic bone disorders.

RECENT FINDINGS

In a physiological context, miRNAs regulate bone formation and bone resorption, thereby contributing to the maintenance of bone homeostasis. Under pathological conditions, an aberrant miRNA signaling contributes to the onset and progression of skeletal disorders, such as osteoporosis. Furthermore, miRNAs can be secreted to circulation and have clinical potential as non-invasive biomarkers. In a therapeutic setting, miRNA delivery or antagonism has been reported to affect several diseases under pre-clinical conditions thereby emerging as novel pharmacological tools. miRNAs are key regulators of bone remodeling in health and disease. The future perspectives in the field include the role of secreted miRNAs in cell-cell communication in the bone environment. Furthermore, the clinical potential of using miRNAs as diagnostic tools and therapeutic targets to treat metabolic bone diseases provides an attractive future direction.

Microarray Analysis of Differentially-expressed MicroRNAs in Acquired Middle Ear Cholesteatoma

Objectives: To analyze the miRNAs expression profiling between acquired middle ear cholesteatoma and normal skin, and to identify several novel miRNAs which may be involved in the etiopathogenesis of middle ear cholesteatoma. Methods: MiRNA microarray technology was adopted to analyze the miRNA expression profiling between acquired middle ear cholesteatoma and normal skin. qRT-PCR was used to validate selected differentially expressed miRNAs. Results: The miRNA microarray technology showed totally 44 upregulated (miRNA-21-3p, miRNA-584-5p, miRNA-16-1-3p, etc) and 175 downregulated (miRNA-10a-5p, miRNA-152-5p, miRNA-203b-5p, etc) miRNAs in cholesteatoma tissues with 2-fold change compared with normal skin. The qRT-PCR validation was in accordance with the microarray results partly: miRNA-21-3p and miRNA-16-1-3p expressed significantly higher while miRNA-10a-5p exhibited an obviously decreased expression in middle ear cholesteatoma tissues when compared with normal skin. The GO and KEGG pathway analyses provided clues that these differentially expressed miRNAs might play essential roles in the etiopathogenesis of middle ear cholesteatoma, including cell proliferation, apoptosis, cell cycle, differentiation, bone resorption and remodeling process. Conclusions: Our study suggests possible roles of differentially expressed miRNAs in the pathogenesis of middle ear cholesteatoma. Targeting on these miRNAs may provide a new strategy for cholesteatoma therapy in the future.

Electroacupuncture Alleviates Surgical Trauma-Induced Hypothalamus Pituitary Adrenal Axis Hyperactivity Via microRNA-142

Electroacupuncture (EA) could improve the hyperactivity of the hypothalamus pituitary adrenal (HPA) axis induced by hepatectomy. However, its underlying mechanism still remains largely unclear. Here, we found that hypothalamic corticotrophin releasing hormone (CRH) modulates the function of the HPA axis, while hepatectomy induced an HPA axis disorder and EA application could regulate the hypothalamic CRH. We first demonstrated that microRNAs (miRNAs) target on CRH via bioinformatics analysis and screened them in the primary hypothalamic neurons. MicroR-142 (miR-142) and miR-376c were identified to inhibit CRH at the mRNA and protein levels, and a dual luciferase reporter assay confirmed their binding to the 3'-untranslated regions (3'-UTR) of CRH. Further analyses revealed a decrease in hypothalamic miR-142 expression in the hepatectomy rats and an increase in miR-142 and miR-376c after EA intervention. Importantly, the improvement effect of EA on the HPA axis regulatory function in hepatectomy rats was blocked by miR-142 antagomir. Our findings illustrated that EA could up-regulate hypothalamic miR-142 expression and decrease the CRH level to alleviate the hyperactivity of the HPA axis induced by hepatectomy.