MiR-152 influences osteoporosis through regulation of osteoblast differentiation by targeting RICTOR

Functional mechanism and clinical implications of mir-1271-5p in pilon fracture healing processes

BACKGROUND

Pilon fractures are challenging to treat and carry a risk of delayed healing. MicroRNA (miRNA) is closely associated with various diseases due to its ability to regulate gene expression. Consequently, this study aimed to examine the connection between miR-1271-5p expression levels and pilon fracture healing processes, while also exploring the underlying mechanisms. The objective of this research was to provide valuable insights for the future clinical treatment of pilon fractures.

MATERIALS

Venous blood samples were obtained for RNA extraction from patients with normal healing (n = 107) or delayed healing (n = 45) of pilon fractures. The expression levels of miR-1271-5p were measured using qRT-PCR. MiR-1271-5p and ZBTB7A biological functions in MC3T3-E1 cells were examined using the Cell Counting Kit-8 (CCK-8), flow cytometry, and qRT-PCR. Finally, an investigation into the underlying mechanisms was carried out using a dual luciferase reporter assay.

RESULTS

This study found that, compared to those who healed normally, patients who experienced delayed healing of pilon fractures had significantly higher expression of miR-1271-5p. This suggests that miR-1271-5p may be an indicator for delayed healing in pilon fractures. Moreover, the upregulation of miR-1271-5p may result in a reduction of ZBTB7A expression, which is thought to mediate the effects of miR-1271-5p on MC3T3-E1 cell activities.

CONCLUSIONS

MiR-1271-5p was involved in the healing processes of pilon fractures via targeting ZBTB7A. MiR-1271-5p was a possible target for the therapy of pilon fractures.

Recent advancements of miRNAs in the treatment of bone diseases and their delivery potential

Advances in understanding miRNAs as endogenous posttranscriptional regulatory units have projected them as novel therapeutics for several untreatable diseases. miRNAs are endogenous non-coding small single-stranded RNA molecules (20-24 nucleotides) with specific gene regulatory functions like repression of mRNA translation by degrading mRNAs. Emerging evidence suggests the role of miRNAs in various stages of bone growth and development. Undoubtedly, due to their critical role in bone remodeling, miRNAs might be projected as a novel approach to treating bone-related diseases. However, the instability associated with miRNAs in their complex environment, such as degradation by nucleases, is a concern. Thus, recent attention is being paid to maintaining the miRNAs' safety and efficacy in the cells. Various efficient delivery systems and chemical modifications of miRNAs are being developed to make them a potential therapeutic option for bone diseases. Here, we have tried to recapitulate the recent advances in the role of miRNAs in bone disease, along with the potential delivery systems for their efficient delivery to the cells.

miRNA-Gene Interaction Network Construction Strategy to Discern Promising Traditional Chinese Medicine against Osteoporosis

Osteoporosis is a widespread bone disease that affects million cases annually. The underlying mechanisms behind the progress of osteoporosis remain enigmatic, which limits detections of biomarkers and therapeutic targets. Hence, this study was aimed at exploring hub molecules to better understand the mechanism of osteoporosis development and discover the traditional Chinese medicine potential drugs for osteoporosis. miRNA and gene expression profiles were downloaded from Gene Expression Omnibus (GEO). Weighted correlation network analysis (WGCNA) was used to identify the key modules for osteoporosis. DIANA Tools was applied to perform pathway enrichment. A miRNA-gene interaction network was constructed, and hub miRNAs and genes were distinguished using Cytoscape software. Receiver operating characteristic (ROC) curves of hub miRNAs and genes were plotted, and correlations with hub genes and osteoporosis-associated factors were evaluated. Potential drugs for osteoporosis in Traditional Chinese Medicine Systems Pharmacology Database and Analysis Platform (TCMSP) were screened, and molecular docking models between these drugs and target genes were showed by AutoDock tools. Two hub modules, 1 miRNA module and 1 gene module, were identified to be the most strongly correlated with osteoporosis by using WGCNA. Then, 3 KEGG pathways including focal adhesion, PI3K-Akt signaling pathway, and gap junction were shared pathways enriched with the miRNAs and genes screened out by WGCNA and differential expression analyses. Finally, after constructing a miRNA-gene interaction network, 6 hub miRNAs (hsa-miR-18b-3p, hsa-miR-361-3p, hsa-miR-484, hsa-miR-519e-5p, hsa-miR-940, and hsa-miR-1275) and 6 hub genes (THBS1, IFNAR2, ARHGAP5, TUBB2B, FLNC, and NTF3) were detected. ROC curves showed good performances of miRNAs and genes for osteoporosis. Correlations with hub genes and osteoporosis-associated factors suggested implicational roles of them for osteoporosis. Based on these hub genes, 3 natural compounds (kainic acid, uridine, and quercetin), which were the active ingredients of 192 herbs, were screened out, and a target-compound-herb network was extracted using TCMSP. Molecular docking models of kainic acid-NTF3, uridine-IFNAR2, and quercetin-THBS1 were exhibited with AutoDock tools. Our study sheds light on the pathogenesis of osteoporosis and provides promising therapeutic targets and traditional Chinese medicine drugs for osteoporosis.

STK11 overexpression prevents glucocorticoid-induced osteoporosis via activating the AMPK/SIRT1/PGC1α axis

Osteoporosis (OP) is a frequent orthopedic disease characterized by pain, fractures and deformities. Glucocorticoids are the most common cause of secondary osteoporosis. Here, we aim to explore the function and mechanism of STK11 in glucocorticoid (GC)-induced OP. Human mesenchymal stromal cells (hMSCs) were differentiated under osteogenic or adipogenic culture medium. An in-vitro OP model was induced by dexamethasone (DEX). The viability, differentiation, apoptosis, and ROS level were evaluated for investigating the functions of SKT11 on hMSCs. The SIRT1 inhibitor EX-527, PGC1α inhibitor SR-18292, and AMPK activator metformin were administered into hMSCs for confirming the mechanism of SKT11. Our results showed that STK11 was down-regulated in OP tissues, as well as DEX-treated hMSCs. Overexpressing STK11 attenuated DEX-mediated inhibition of osteogenic differentiation and heightened the activation of the AMPK/SIRT1/PGC1α pathway, whereas STK11 knockdown exerted opposite effects. Inhibiting SIRT1 or PGC1α repressed the promotive effect of STK11 on osteogenic differentiation of hMSCs, while activation of AMPK abated the inhibitory effect of STK11 knockdown on osteogenic differentiation of hMSCs. In conclusion, this study revealed that overexpressing STK11 dampened GC-induced OP by activating the AMPK/SIRT1/PGC1α axis.

High-mobility group box chromosomal protein-1 deletion alleviates osteoporosis in OVX rat model via suppressing the osteoclastogenesis and inflammation

Background

Osteoporosis is a skeletal metabolic disease that constitutes a great threaten to human health. However, there is currently no gold standard for its treatment. High-mobility group box chromosomal protein-1 (HMGB-1) has been reported to play an important role in various orthopedic diseases. Till now, its role in osteoporosis remains elusive.

Methods

Rats underwent ovariectomy (OVX) were used to construct a postmenopausal model of osteoporosis. Then, rats were divided into sham groups without OVX surgery, OVX model group, HMGB-1 knockdown (HMGB-1 KD) OVX model groups. The expression of HMGB1 was evaluated by qRT-PCR and western blotting. Subsequently, the changes of trabeculae were evaluated by micro-computed tomography (CT) assay. Skeletal necrosis and metabolism were further analyzed by hematoxylin–eosin (HE) staining, Alcian blue staining and Masson’s trichrome staining. The contents of serum alkaline phosphatase (ALP) and osteocalcin were detected by ELISA assay. Expression of osteoclast-associated receptor (OSCAR) and tartrate-resistant acid phosphatase (TRAP) were determined to investigate the effects of HMGB-1 loss on osteoclastogenesis.

Results

Single HMGB-1 deletion exerted no significant effect on rat trabeculae, serum ALP and osteocalcin. Noticeably, HMGB1 knockdown dramatically ameliorated OVX-induced changes in above indexes. Trabeculae structures of OVX rats were sparse with disorder arrangement, which were greatly recovered after HMGB-1 deletion. Enhanced osteoclastogenesis was observed in OVX rats by increasing number of TRAP + cells and expression of TRAP and OSCAR, and loss of HMGB1 ameliorated osteoclastogenesis in OVA rats. Moreover, HMGB-1 deletion antagonized OVX-evoked downregulation of osteoblast activity markers osterix (OSX), collagen type I alpha 1(COL1A1) and distal-less homeobox 2 (DLX2) protein. Furthermore, loss of HMGB-1 attenuated fluctuation of inflammatory factors in OVX rats. Additionally, HMGB-1 deficiency inhibited OVX-evoked activation of the Toll-like receptor (TLR) 4/NF-κB signaling pathway. Moreover, reactivating the TLR4 signaling further aggravated OVX-induced osteoporosis, which was reversed by HMGB1 knockdown.

Conclusion

HMGB-1 deletion alleviated OVX-triggered osteoporosis by suppressing osteoclastogenesis and inflammatory disorder via the inhibition of the TLR4 signaling. Therefore, HMGB-1 may be a promising therapeutic target for osteoporosis.

Dysregulation of the HOTAIR-miR-152-CAMKIIα Axis in Craniosynostosis Results in Impaired Osteoclast Differentiation

Craniosynostosis is one of the most common craniofacial deformities demanding surgical treatment in infancy. LncRNA HOTAIR has verified its important role in osteogenesis and osteoarthritis. However, whether HOTAIR plays an essential role in the development of craniosynostosis is still unclear. In this study, we aimed to investigate the molecular role of HOTAIR in the osteoclast function and development of craniosynostosis.For osteoclast differentiation, RAW264.7 cells were induced by 50 ng/ml of RANKL and 10 ng/mL M-CSF, followed by TRAP staining. Cell proliferation and apoptosis were assayed by the CCK-8 kit and Annexin V-FITC apoptosis detection kit, respectively. The expression of HOTAIR was determined in PBMCs by qRT-PCR. Protein levels of all those involved genes were measured by Western blot assay. A luciferase reporter assay was used to determine the miRNA target validation. The HOTAIR expression in PBMCs from children with craniosynostosis was significantly downregulated. The results of cell proliferation and apoptosis assays indicated that silencing of HOTAIR could inhibit osteoclast differentiation and increase cell apoptosis. Moreover, the luciferase reporter assay revealed that the regulatory axis and HOTAIR-miR-152-CAMKIIα were the regulatory mechanisms of HOTAIR in the osteoclast function and development of craniosynostosis.In this study, our data showed that HOTAIR could promote osteoclast differentiation by binding miR-152. Furthermore, the HOTAIR/HOTAIR-miR-152-CAMKIIα axis was found to regulate osteoclast differentiation. These results indicate that the HOTAIR plays a crucial role in the development of osteoclasts.

The Emerging Role of MicroRNAs in Bone Diseases and Their Therapeutic Potential

MicroRNAs (miRNAs) are a class of small (20-24 nucleotides), highly conserved, non-coding RNA molecules whose main function is the post-transcriptional regulation of gene expression through sequence-specific manners, such as mRNA degradation or translational repression. Since these key regulatory molecules are implicated in several biological processes, their altered expression affects the preservation of cellular homeostasis and leads to the development of a wide range of pathologies. Over the last few years, relevant investigations have elucidated that miRNAs participate in different stages of bone growth and development. Moreover, the abnormal expression of these RNA molecules in bone cells and tissues has been significantly associated with the progression of numerous bone diseases, including osteoporosis, osteosarcoma, osteonecrosis and bone metastasis, among others. In fact, miRNAs regulate multiple pathological mechanisms, including altering either osteogenic or osteoblast differentiation, metastasis, osteosarcoma cell proliferation, and bone loss. Therefore, in this present review, aiming to impulse the research arena of the biological implications of miRNA transcriptome in bone diseases and to explore their potentiality as a theragnostic target, we summarize the recent findings associated with the clinical significance of miRNAs in these ailments.

MicroRNA miR-18a-3p promotes osteoporosis and possibly contributes to spinal fracture by inhibiting the glutamate AMPA receptor subunit 1 gene (GRIA1)

The promoting role that miR-18a-3p plays in osteoporosis (OP) has been previously described. However, the detailed mechanisms remain unclear. Bone tissues were collected from healthy patients, OP patients, and patients with osteoporotic spinal fractures. An osteogenic differentiation of human bone marrow mesenchymal stem cells (hBMSCs) was constructed to detect the expression of miR-18a-3p and glutamate AMPA receptor subunit 1 (GRIA1). Alkaline phosphatase (ALP) activity and a qRT-PCR analysis were used to detect ALP content, alizarin red S staining was used to detect calcium deposition, and qRT-PCR was used to evaluate runt-related transcription factor 2 (RUNX2), osteocalcin (OCN), and osteopontin (OPN) expression levels. A dual-luciferase reporter and RNA pull-down assay was used to verify the targeted correlation between miR-18a-3p and GRIA1. We observed an increase in miR-18a-3p expression and a decrease in GRIA1 expression in OP and osteoporotic vertebral fracture patients. Upregulation of miR-18a-3p restrained the activity and expression of ALP in hBMSCs, inhibited the expression of RUNX2, OCN, and OPN, and inhibited calcium deposition. Knockdown of miR-18a-3p or upregulation of GRIA1 promoted osteogenic differentiation. Our findings indicate that miR-18a-3p promotes OP progression by regulating GRIA1 expression, suggesting that targeting miR-18a-3p/GRIA1 may be a therapeutic strategy for OP.

Circulating miR-122-5p and miR-375 as Potential Biomarkers for Bone Mass Recovery after Parathyroidectomy in Patients with Primary Hyperparathyroidism: A Proof-of-Concept Study

Primary hyperparathyroidism (PHPT) is the leading cause of secondary osteoporosis. Although bone mineral density (BMD) tends to recover after parathyroidectomy in PHPT patients, the degree of recovery varies. Circulating microRNAs (miRNAs) profiles are known to be correlated with osteoporosis and fracture. We aimed to investigate whether osteoporotic fracture-related miRNAs are associated with postoperative BMD recovery in PHPT. Here, 16 previously identified osteoporotic fracture-related miRNAs were selected. We analyzed the association between the preoperative level of each miRNA and total hip (TH) BMD change. All 12 patients (among the 18 patients enrolled) were cured of PHPT after parathyroidectomy as parathyroid hormone (PTH) and calcium levels were restored to the normal range. Preoperative miR-19b-3p, miR-122-5p, and miR-375 showed a negative association with the percent changes in TH BMD from baseline. The association remained robust for miR-122-5p and miR-375 even after adjusting for sex, age, PTH, and procollagen type 1 N-terminal propeptide levels in a multivariable model. In conclusion, preoperative circulating miR-122-5p and miR-375 levels were negatively associated with TH BMD changes after parathyroidectomy in PHPT patients. miRNAs have the potential to serve as predictive biomarkers of treatment response in PHPT patients, which merits further investigation.

Contribution of miRNAs and lncRNAs in osteogenesis and related disorders

Non-coding RNAs have been found to regulate several developmental processes among them is osteogenesis. Although these transcripts have several distinct classes, two classes i.e. microRNAs and long non-coding RNAs have attained more attention. These transcripts regulate intramembranous as well as endochondral ossification processes. The effects of microRNAs on osteogenesis are mostly mediated through modulation of Wnt/β-catenin and TGFβ/BMP pathways. Long non-coding RNAs can directly affect expression of these pathways or osteogenic transcription factors. Moreover, they can serve as a molecular sponge for miRNAs. MALAT1/miR-30, MALAt1/miR-214, LEF1-AS1/miR-24-3p, MCF2L-AS1/miR-33a, MSC-AS1/miR-140-5p and KCNQ1OT1/miR-214 are examples of such kind of interaction between lncRNAs and miRNAs in the context of osteogenesis. In the current paper, we explain these two classes of non-coding RNAs in the osteogenesis and related disorders.

miRNA Let-7a-5p targets RNA KCNQ1OT1 and Participates in Osteoblast Differentiation to Improve the Development of Osteoporosis

It is known that miRNA mediates the formation of osteogenesis, but the mechanism by which miRNA let-7a-5p regulates osteogenesis in osteoporosis (OP) is not yet understood. This paper aims to probe into the regulatory mechanism of miRNA let-7a-5p in the development of OP. Fresh femoral trabecular bones of patients with osteoporotic fracture (OP group, n = 25) and non-OP osteoarthritis (Non-OP group, n = 23) who underwent hip replacement in our hospital from December 2016 to December 2019 were collected. The expression and protein levels of miRNA let-7a-5p and V-AKT murine thymoma viral oncogene homolog 3 (RNA KCNQ1OT1) were detected. C2C12 cells were purchased and osteogenic differentiation model was constructed by BMP2 induction. After miRNA let-7a-5p up-regulation or down-regulation by transfection of corresponding mimics and inhibitors, the impacts of miRNA let-7a-5p and RNA KCNQ1OT1 on osteogenic differentiation-related factors (OC, ALP, COL1A1) in C2C12 cells were analyzed. The determination of targeting correlation of miRNA let-7a-5p with RNA KCNQ1OT1 was performed by dual-luciferase reporter (DLR). In OP samples, miRNA let-7a-5p was notably declined while RNA KCNQ1OT1 were remarkably up-regulated. MiRNA let-7a-5p reduced in C2C12 cells as BMP2 treatment proceeded. MiRNA let-7a-5p up-regulation or RNA KCNQ1OT1 down-regulation increased OC, ALP, COL1A1 levels and ALP activity. RNA KCNQ1OT1 was directly targeted to miR-497-5p. RNA KCNQ1OT1 up-regulation weakened the promoting effect of miRNA let-7a-5p up-regulation on osteoblast differentiation. MiRNA let-7a-5p up-regulation can target to reduce RNA KCNQ1OT1 and promote osteoblast differentiation, thereby improving the development of osteoporosis.

miR-25-3p promotes proliferation and inhibits autophagy of renal cells in polycystic kidney mice by regulating ATG14-Beclin 1

MicroRNAs are involved in the regulation of the autophagy and proliferation in several diseases. This study aims to verify the role of miR-25-3p in the proliferation and autophagy of renal cells in polycystic kidney disease (PKD). We found that kidney to body weight and blood urea content were increased in PKD mice. Cystic dilations were increased in kidney tissue from PKD mice, and autophagy-related protein ULK1 and the ratio of LC3-II/LC3-I were decreased, indicating autophagy was inhibited in PKD mice. In addition, miR-25-3p was upregulated in PKD mice, and inhibition of miR-25-3p decreased cystic dilations in kidney tissues, increased ULK1 expression and the ratio of LC3-II/LC3-I, indicating inhibition of miR-25-3p enhanced the autophagy in PKD. Besides, inhibition of miR-25-3p suppressed the proliferation of renal cells and downregulated E2F-1 and PCNA expressions. Importantly, miR-25-3p targetedly suppressed ATG14 expression in PKD cells. Finally, silencing ATG14 abolished the inhibition effect of miR-25-3p inhibitor on renal cell proliferation, and reversed the inhibition effect of miR-25-3p inhibitor on E2F-1 and PCNA expressions in in vitro and in vivo experiments, which suggested that ATG14 was involved in the regulation of miR-25-3p-mediated kidney cell proliferation. Therefore, inhibition of miR-25-3p promoted cell autophagy and suppressed cell proliferation in PKD mice through regulating ATG14.

Downregulating microRNA-152-3p promotes the viability and osteogenic differentiation of periodontal ligament stem cells via targeting integrin alpha 5

OBJECTIVE

The aim of this study was to investigate the role of microRNA-152-3p (miR-152-3p) in the osteogenic differentiation of human periodontal ligament stem cells (hPDLSCs).

DESIGN

HPDLSCs were isolated and identified using immunofluorescence staining, and their osteogenic differentiation capability was evaluated by alkaline phosphatase staining and Alizarin Red staining. HPDLSC viability was measured using cell counting kit-8. alkaline phosphatase level in hPDLSCs was measured by enzyme-linked immunosorbent assay. Target gene and potential binding sites between miR-152-3p and integrin alpha 5 (ITGA5) were predicted using TargetScan and confirmed by dual-luciferase reporter assay. Relative expressions of miR-152-3p and factors related to hPDLSC osteogenic differentiation were measured by quantitative real-time polymerase chain reaction and Western blot as needed.

RESULTS

Collected cells were observed and identified as hPDLSCs. MiR-152-3p expression was downregulated during hPDLSC osteogenic differentiation in a time-dependent manner, and downregulating miR-152-3p promoted cell viability, enhanced alkaline phosphatase level, and increased the expressions of genes related to hPDLSC osteogenic differentiation. ITGA5 was the target gene of miR-152-3p and ITGA5 expression was upregulated during osteogenic differentiation in a time-dependent manner. Silencing ITGA5 partially reversed the effects of downregulating miR-152-3p on hPDLSCs.

CONCLUSION

Downregulating miR-152-3p may promote hPDLSC viability and osteogenic differentiation via targeting ITGA5, and have potential effects on periodontal and alveolar bone regeneration.

MicroRNA-505 is involved in the regulation of osteogenic differentiation of MC3T3-E1 cells partially by targeting RUNX2

Objective

Evidence suggests that microRNAs (miRNAs) regulate the expression of genes involved in bone metabolism. This study aimed to investigate the role of miR-505 in the osteogenic differentiation of MC3T3-E1 cells.

Methods

We performed miRNA sequencing to identify differentially expressed miRNAs between MC3T3-E1 cells treated with osteogenic induction medium (OIM) and control cells. Bioinformatics analysis was performed by using the TargetScan and miRDB databases. The expression of miR-505 in MC3T3-E1 cells was detected during osteogenic differentiation. After transfection with miR-505 mimic or miR-505 inhibitor, MC3T3-E1 cells were induced to differentiate into osteoblasts, and the expression of osteogenic differentiation markers (Runt-related transcription factor 2 (RUNX2), alkaline phosphatase (ALP), osteopontin (OPN), osteocalcin (OCN), and osterix (OSX)) was detected.

Results

miR-505 was the most downregulated miRNA among the differentially expressed miRNAs. The RUNX2 gene was identified as a potential target of miR-505 using the target prediction program. miR-505 expression was downregulated during osteogenic differentiation of MC3T3-E1 cells. The expression of osteogenic marker genes was inhibited in MC3T3-E1 cells after transfection with miR-505. However, the expression of osteogenic marker genes was upregulated after transfection with miR-505 inhibitor.

Conclusion

This study is the first to report miR-505 could bind to the RUNX2 gene and thus regulate partly the dysfunction of osteoblasts differentiation, which is expected to be targets for the treatment of osteoporosis.