Circular RNA circ_0011269 sponges miR-122 to regulate RUNX2 expression and promotes osteoporosis progression

Circular RNAs (circRNAs) are a novel class of noncoding RNAs that are widely expressed in human disease. However, circRNAs expression profile and potential mechanism in osteoporosis pathogenesis remain to be further studied. In the present study, a total of 69 circRNAs were identified to be abnormally expressed in osteoporosis patient samples by microarray and bioinformatics analyses. We found that circ_0011269 was notably downregulated in osteoporosis (fold change, 3.94). By means of miRanda algorithm, we constructed the interaction network of circ_0011269-miRNAs in osteoporosis based on target binding and miR-122 was enrolled in the network. Dual-luciferase reporter assay verified the target relationship of miR-122 and circ_0011269/RUNX2. The expression of circ_0011269 and RUNX2 were gradually increased during osteogenic differentiation while miR-122 exhibited a decreased expression. Moreover, overexpression of circ_0011269 could promote RUNX2 expression and inhibit osteoporosis. In summary, this study found that circ_0011269 sponges miR-122 to regulate RUNX2 expression and promotes osteoporosis progression.     

MiRNA-1271-5p regulates osteogenic differentiation of human bone marrow-derived mesenchymal stem cells by targeting forkhead box O1 (FOXO1)

Forkhead box O1 (FOXO1) is a key regulator of osteogenesis. The aim of this study was to identify the mechanisms of microRNAs (miRNAs) targeting FOXO1 in osteogenic differentiation of human bone marrow mesenchymal stem cells (hMSCs). Three miRNA target prediction programs were used to search for potential miRNAs that target FOXO1. Quantitative real-time polymerase chain reaction was conducted to detect the expression of miR-1271-5p and FOXO1 during osteogenic differentiation. Target gene prediction and screening, luciferase reporter assay was used to verify the downstream target gene of miR-1271-5p. The expression levels of FOXO1 and Runx2 were detected by RT-qPCR and Western blot analysis. Alkaline phosphatase (ALP) activity and matrix mineralization were detected by biochemical methods. The expression levels of Runx2, ALP, and osteocalcin were detected by RT-qPCR. Our results showed that miR-1271-5p was downregulated during osteogenic induction. And the expression levels of miR-1271-5p were higher in osteoporotic tissues than that in adjacent nonosteoporotic tissues. The expression levels of FOXO1 were lower in osteoporotic tissues than that in adjacent nonosteoporotic tissues. And a negative correlation was found between miR-1271-5p and FOXO1 in osteoporotic tissues. Overexpression of miR-1271-5p downregulated FOXO1 and inhibited osteogenic differentiation in hMSCs. Overexpression of miR-1271-5p downregulated the expression of osteogenic markers and reduced ALP activity. In addition, ectopic expression of FOXO1 reversed the effect of miR-1271-5p on osteogenic differentiation. In conclusion, miR-1271-5p functioned as a therapeutic target of osteogenic differentiation in hMSCs by inhibiting FOXO1, which provides valuable insights into the use of miR-1271-5p as a target in the treatment of osteoporosis and other bone metabolic diseases.     

Circular RNA CircSLC8A1 contributes to osteogenic differentiation in hBMSCs via CircSLC8A1/miR-144-3p/RUNX1 in periprosthetic osteolysis

Circular RNAs (circRNAs) are often found in eukaryocyte and have a role in the pathogenesis of a variety of human disorders. Our related research has shown the differential expression of circRNAs in periprosthetic osteolysis (PPOL). However, the involvement of circRNAs in the exact process is yet unknown. CircSLC8A1 expression was evaluated in clinical samples and human bone marrow mesenchymal stem cells (hBMSCs) in this investigation using quantitative real-time PCR. In vitro and in vivo studies were conducted to explicate its functional role and pathway. We demonstrated CircSLC8A1 is involved in PPOL using gain- and loss-of-function methods. The association of CircSLC8A1 and miR-144-3p, along with miR-144-3p and RUNX1, was predicted using bioinformatics. RNA pull-down and luciferase assays confirmed it. The impact of CircSLC8A1 in the PPOL-mouse model was also investigated using adeno-associated virus. CircSLC8A1 was found to be downregulated in PPOL patients' periprosthetic tissues. Overexpression of CircSLC8A1 promoted osteogenic differentiation (OD) and inhibited apoptosis of hBMSCs in vitro. The osteogenic markers of RUNX1, osteopontin (OPN) and osteocalcin (OCN) were significantly upregulated in hBMSCs after miR-144-3p inhibitor was transferred. Mechanistic analysis demonstrated that CircSLC8A1 directly bound to miR-144-3p and participated in PPOL through the miR-144-3p/RUNX1 pathway in hBMSCs. Micro-CT and quantitative analysis showed that CircSLC8A1 markedly inhibited PPOL, and osteogenic markers (RUNX1, OPN and OCN) were significantly increased (P<0.05) in the mice model. Our findings prove that Circ SLC8A1 exerted a regulatory role in promoting osteogenic differentiation in hBMSCs, and CircSLC8A1/miR-144-3p/RUNX1 pathway may provide a potential target for prevention of PPOL.     

Long non-coding RNA DANCR modulates osteogenic differentiation by regulating the miR-1301-3p/PROX1 axis

The balance of osteoblasts and marrow adipocytes from bone marrow mesenchymal stem cells (BM-MSCs) maintains bone health. Under aging or other pathological stimuli, BM-MSCs will preferentially differentiate into marrow adipocytes and reduce osteoblasts, leading to osteoporosis. Long non-coding RNA differentiation antagonizing non-protein coding RNA (DANCR) participates in the osteogenic differentiation of human BM-MSCs, but the mechanism by which DANCR regulates the osteogenic differentiation of human BM-MSCs has not been fully explained. We observed that DANCR and prospero homeobox 1 (PROX1) were downregulated during osteogenic differentiation of human BM-MSCs, while miR-1301-3p had an opposite trend. DANCR overexpression decreased the levels of alkaline phosphatase, RUNX2, osteocalcin, Osterix in BM-MSCs after osteogenic induction, but DANCR silencing had the opposite result. Moreover, DANCR sponged miR-1301-3p to regulate PROX1 expression. miR-1301-3p overexpression reversed the suppressive role of DANCR elevation on the osteogenic differentiation of human BM-MSCs. Also, PROX1 elevation abolished the promoting role of miR-1301-3p overexpression on the osteogenic differentiation of human BM-MSCs. In conclusion, DANCR suppressed the osteogenic differentiation of human BM-MSCs through the miR-1301-3p/PROX1 axis, offering a novel mechanism by which DANCR is responsible for the osteogenic differentiation of human BM-MSCs.

     

MiR-210-3p inhibits osteogenic differentiation and promotes adipogenic differentiation correlated with Wnt signaling in ERα-deficient rBMSCs

MicroRNAs (miRNAs) regulate activities in living organisms through various signaling pathways and play important roles in the development and progression of osteoporosis. The balance between osteogenic and adipogenic differentiation of rBMSCs is closely related to the occurrence of osteoporosis. ERα regulates bone metabolism in various tissues. However, the correlation among ERα, miRNAs, and the differentiation of rBMSCs is still unclear. In this study, we used lentivirus transfection into rBMSCs to construct an ERα-deficient model, analyzed the differences in expressed miRNAs between control and ERα-deficient rBMSCs. The results revealed that the expression of 25 miRNAs were upregulated, 164 miRNAs were downregulated, and some of the regulated miRNAs such as miR-210-3p and miR-214-3p were related to osteogenic or adipogenic differentiation, as well as to particular signaling pathways. Next, we overexpressed miR-210-3p to evaluate its effects on the osteogenic and adipogenic differentiation of rBMSCs, and identified the relationship among miR-210-3p, Wnt signaling pathway, and the differentiation of rBMSCs. The results indicated that ERα-deficient inhibited osteogenic differentiation, promoted adipogenic differentiation, and regulated the expression of some miRNAs. Meanwhile, overexpression of miR-210-3p promoted osteogenic differentiation and inhibited adipogenic differentiation of rBMSCs, processes likely to be related to the Wnt signaling pathway. In conclusion, we identified a group of upregulated and downregulated miRNAs in ERα-deficient rBMSCs that might play a vital role in regulating osteogenic or adipogenic differentiation. One of these, miR-210-3p, inhibited osteogenic differentiation and promoted adipogenic differentiation correlated with the Wnt signaling pathway in ERα-deficient rBMSCs, providing new insight into the regulation of bone metabolism.     

MiR-664-3p suppresses osteoblast differentiation and impairs bone formation via targeting Smad4 and Osterix

Osteoporosis is a metabolic disorder characterized by low bone mass and deteriorated microarchitecture, with an increased risk of fracture. Some miRNAs have been confirmed as potential modulators of osteoblast differentiation to maintain bone mass. Our miRNA sequencing results showed that miR-664-3p was significantly down-regulated during the osteogenic differentiation of the preosteoblast MC3T3-E1 cells. However, whether miR-664-3p has an impact on bone homeostasis remains unknown. In this study, we identified overexpression of miR-664-3p inhibited the osteoblast activity and matrix mineralization in vitro. Osteoblastic miR-664-3p transgenic mice exhibited reduced bone mass due to suppressed osteoblast function. Target prediction analysis and experimental validation confirmed Smad4 and Osterix (Osx) are the direct targets of miR-664-3p. Furthermore, specific inhibition of miR-664-3p by subperiosteal injection with miR-664-3p antagomir protected against ovariectomy-induced bone loss. In addition, miR-664-3p expression was markedly higher in the serum from patients with osteoporosis compared to that from normal subjects. Taken together, this study revealed that miR-664-3p suppressed osteogenesis and bone formation via targeting Smad4 and Osx. It also highlights the potential of miR-664-3p as a novel diagnostic and therapeutic target for osteoporotic patients.     

MiR-26b-3p regulates osteoblast differentiation via targeting estrogen receptor α

BackgroundUnderstanding of the molecular mechanisms of miRNAs involved in osteoblast differentiation is important for the treatment of bone-related diseases.MethodsMC3T3-E1 cells were induced to osteogenic differentiation by culturing with bone morphogenetic protein 2 (BMP2). After transfected with miR-26b-3p mimics or inhibitors, the osteogenic differentiation of MC3T3-E1 cells was detected by ALP and ARS staining. Cell viability was analyzed by MTT. The expressions of miR-26b-3p and osteogenic related markers and signaling were examined by qPCR and western blot. Direct binding of miR-26b-3p and ER-α were determined by dual luciferase assay.ResultsmiR-26b-3p was significantly down-regulated during osteoblast differentiation. Overexpression of miR-26b-3p inhibited osteoblast differentiation, while inhibition of miR-26b-3p enhanced osteoblast differentiation. Further studies demonstrated miR-26b-3p inhibited the expression of estrogen receptor α (ER-α) by directly targeting to the CDS region of ER-α mRNA. Overexpression of ER-α rescued the suppression effects of miR-26b-3p on osteoblast differentiation, while knockdown of ER-α reversed the upregulation of osteoblast differentiation induced by knockdown of miR-26b-3p.ConclusionOur study demonstrates that miR-26b-3p suppresses osteoblast differentiation of MC3T3-E1 cells via directly targeting ER-α.     

miR-30 family members negatively regulate osteoblast differentiation

miRNAs are endogenously expressed 18- to 25-nucleotide RNAs that regulate gene expression through translational repression by binding to a target mRNA. Recently, it has been indicated that miRNAs are closely related to osteogenesis. Our previous data suggested that miR-30 family members might be important regulators during the biomineralization process. However, whether and how they modulate osteogenic differentiation have not been explored. In this study, we demonstrated that miR-30 family members negatively regulate BMP-2-induced osteoblast differentiation by targeting Smad1 and Runx2. Evidentially, overexpression of miR-30 family members led to a decrease of alkaline phosphatase activity, whereas knockdown of them increased the activity. Then bioinformatic analysis identified potential target sites of the miR-30 family located in the 3' untranslated regions of Smad1 and Runx2. Western blot analysis and quantitative RT-PCR assays demonstrated that miR-30 family members inhibit Smad1 gene expression on the basis of repressing its translation. Furthermore, dual-luciferase reporter assays confirmed that Smad1 is a direct target of miR-30 family members. Rescue experiments that overexpress Smad1 and Runx2 significantly eliminated the inhibitory effect of miR-30 on osteogenic differentiation and provided strong evidence that miR-30 mediates the inhibition of osteogenesis by targeting Smad1 and Runx2. Also, the inhibitory effects of the miR-30 family were validated in mouse bone marrow mesenchymal stem cells. Therefore, our study uncovered that miR-30 family members are key negative regulators of BMP-2-mediated osteogenic differentiation.     

Osteoclast-derived miR-23a-5p-containing exosomes inhibit osteogenic differentiation by regulating Runx2

BackgroundSome microRNAs (miRNAs) are involved in osteogenic differentiation. In recent years, increasing evidences have revealed that exosomes contain specific miRNAs. However, the effect and mechanism of miR-23a-5p-containing exosomes in osteoblast remain largely unclear.MethodsWe extracted exosomes from RANKL-induced RAW 264.7 cells, and identified exosomes via transmission electron microscopy, western blot and flow cytometry analysis. In addition, exosome secretion was inhibited by GW4869 and Rab27a siRNAs. miR-23a-5p expression was analyzed by qRT-PCR, and the related protein levels were examined by western blot assay. Furthermore, the number and distribution of osteoclasts were detected by TRAP staining, and early osteogenesis was evaluated by ALP staining. Combination of YAP1 and Runx2 was verified by Co-IP assay, and the regulation of miR-23a-5p and Runx2 was measured by dual luciferase reporter assay.ResultsWe successfully extracted exosomes from RANKL-induced RAW 264.7 cells, and successfully verified exosomes morphology. We also indicated that miR-23a-5p was highly expressed in exosomes from RANKL-induced RAW 264.7 cells, and osteoclast-derived miR-23a-5p-containing exosomes inhibited osteoblast activity, while its inhibition weakened osteoclasts. In mechanism, we demonstrated that Runx2 was a target gene of miR-23a-5p, YAP interacted with Runx2, and YAP or Runx2 inhibited MT1DP expression. In addition, we proved that knockdown of MT1DP facilitated osteogenic differentiation by regulating FoxA1 and Runx2.ConclusionsWe demonstrated that osteoclast-derived miR-23a-5p-containing exosomes could efficiently suppress osteogenic differentiation by inhibiting Runx2 and promoting YAP1-mediated MT1DP. Therefore, we suggested miR-23a-5p in exosomes might provide a novel mechanism for osteoblast function.     

miR-141-3p inhibits human stromal (mesenchymal) stem cell proliferation and differentiation

Wnt signaling determines human stromal (mesenchymal) stem cell (hMSC) differentiation fate into the osteoblast or adipocyte lineage. microRNAs (miRNAs) are small RNA molecules of 21–25 nucleotides that regulate many aspects of osteoblast biology. Thus, we examined miRNAs regulated by Wnt signaling in hMSC. We identified miRNA (miR)-141-3p as a Wnt target which in turn inhibited Wnt signaling. Moreover, miR-141-3p inhibited hMSC proliferation by arresting cells at the G1 phase of the cell cycle. miR-141-3p inhibited osteoblast differentiation of hMSC as evidenced by reduced alkaline phosphatase activity, gene expression and in vitro mineralized matrix formation. Bioinformatic studies, Western blot analysis and 3’UTR reporter assay demonstrated that cell division cycle 25A (CDC25A) is a direct target of miR-141-3p. siRNA-mediated knock-down of CDC25A inhibited hMSC proliferation and osteoblast differentiation. In summary, miR-141-3p acts as a negative regulator of hMSC proliferation and osteoblast differentiation. Targeting miR-141-3p could be used as an anabolic therapy of low bone mass diseases, e.g. osteoporosis.     

miR-27 promotes osteoblast differentiation by modulating Wnt signaling

Canonical Wnt signaling is particularly important for differentiation of human mesenchymal stem cells into osteoblast. MicroRNAs (miRNAs) also play an essential role in regulating cell differentiation. However, the role of miRNAs in osteoblast differentiation remains poorly understood. Here we found that the expression of miR-27 was increased during hFOB1.19 cells differentiation. Moreover, ectopic expression of miR-27 promoted hFOB1.19 cells differentiation, whereas its repression was sufficient to inhibit cell differentiation. Western blot analysis showed that the expression level of miR-27 was positively correlated with that of β-catenin, a key protein in Wnt signaling. Further, we verified that miR-27 directly targeted and inhibited adenomatous polyposis coli (APC) gene expression, and activated Wnt signaling through accumulation of β-catenin. This study suggests miR-27 is an important mediator of osteoblast differentiation, thus offering a new target for the development of preventive or therapeutic agents against osteogenic disorders.