Osteoporosis In Mice Research Articles

Let-7a-5p inhibits BMSCs osteogenesis in postmenopausal osteoporosis mice

PurposeThe aim of this study was to investigate the mechanism of let-7a-5p in osteogenic differentiation of bone marrow mesenchymal stem cells (BMSCs) in postmenopausal osteoporosis (PMOP) mice. MethodsA mouse model of PMOP was established and osteoporosis model was identified by micro-CT scan. BMSCs in the sham group and PMOP group were cultured and osteogenic differentiation was induced. The expression of let-7a-5p in BMSCs was detected by qRT-PCR, and BMSCs was induced by osteogenic differentiation in sham and PMOP group. The BMSCs treated by let-7a-5p mimics, let-7a-5p inhibitor and negative control were named as let-7a-5p mimics group, mimics NC group, let-7a-5p inhibitor group and inhibitor NC group, respectively. ALP staining and alizarin red staining were used to detect osteogenic differentiation ability, qRT-PCR and western blot were used to detect the expression of Runt-related transcription factor 2 (Runx2) and Osterix. The targeting relationship between let-7a-5p and TGFBR1 were verificated by target scan and luciferase reporter gene assay. ResultsThe PMOP mouse model was successfully established. The expression of let-7a-5p in BMSCs of PMOP group was significantly higher than that in the sham group (P < 0.05). Let-7a-5p reduced the expression of ALP and the formation of calcified nodules, while also inhibited the expression of Runx2 and Osterix. TGFBR1 is the target gene of let-7a-5p. ConclusionLet-7a-5p might inhibit the osteogenic differentiation of BMSCs in PMOP mice by regulating TGFBR1.

MicroRNA-705 regulates the differentiation of mouse mandible bone marrow mesenchymal stem cells.

The craniofacial skeleton is the foundation of most stomatological treatments, including prosthodontics and maxillofacial surgery. Although histologically similar to the appendicular skeleton, the craniofacial skeleton manifests many unique properties in response to external stimuli and signals. However, the mandibular or maxillary bone marrow mesenchyme, which is the intrinsic foundation of the functions of craniofacial skeleton, has not been well studied, and its homeostasis mechanism remains elusive. Osteoporosis is a systemic disease that affects all skeletons and is characterized by bone mass loss. Osteoporotic bone marrow mesenchymal stem cells (BMMSCs) exhibit disturbed homeostasis and distorted lineage commitment. Many reports have shown that microRNAs (miRNAs) play important roles in regulating MSCs homeostasis. Here, to obtain a better understanding of mandibular bone marrow MSCs homeostasis, we isolated and cultured mandible marrow MSCs from mouse mandibles. Using miR-705 mimics and an inhibitor, we demonstrated that miR-705 played a vital role in shifting the mandibular MSCs lineage commitment in vitro. Utilizing an osteoporosis mouse model, we demonstrated that MSCs from ovariectomized (OVX) mouse mandibular bone marrow exhibited impaired osteogenic and excessive adipogenic differentiation. miR-705 was found overexpressed in OVX mandibular MSCs. The knock down of miR-705 in vitro partially attenuated the differentiation disorder of the OVX mandibular MSCs by upregulating the expression of osteogenic marker genes but suppressing adipogenic genes. Taken together, our findings provide a better understanding of the homeostasis mechanism of mandibular BMMSCs and a novel potential therapeutic target for treating mandibular osteoporosis.

Aptamer-functionalized exosomes from bone marrow stromal cells target bone to promote bone regeneration.

In elderly people particularly in postmenopausal women, inadequate bone formation by osteoblasts originating from bone marrow mesenchymal stem cells (BMSCs) for compensation of bone resorption by osteoclasts is a major reason for osteoporosis. Enhancing osteoblastic differentiation of BMSCs is a feasible therapeutic strategy for osteoporosis. Here, bone marrow stromal cell (ST)-derived exosomes (STExos) are found to remarkably enhance osteoblastic differentiation of BMSCs in vitro. However, intravenous injection of STExos is inefficient in ameliorating osteoporotic phenotypes in an ovariectomy (OVX)-induced postmenopausal osteoporosis mouse model, which may be because STExos are predominantly accumulated in the liver and lungs, but not in bone. Hereby, the STExo surface is conjugated with a BMSC-specific aptamer, which delivers STExos into BMSCs within bone marrow. Intravenous injection of the STExo-Aptamer complex enhances bone mass in OVX mice and accelerates bone healing in a femur fracture mouse model. These results demonstrate the efficiency of BMSC-specific aptamer-functionalized STExos in targeting bone to promote bone regeneration, providing a novel promising approach for the treatment of osteoporosis and fracture.

Pyrroloquinoline Quinone Prevents Estrogen Deficiency-Induced Osteoporosis by Inhibiting Oxidative Stress and Osteocyte Senescence.

Accumulating studies have shown that oxidative stress increases with aging, which is related to the pathophysiology of postmenopausal osteoporosis. Pyrroloquinoline quinone (PQQ) is a natural anti-oxidant with anti-oxidative and anti-aging effects. However, it is unclear whether PQQ has a protective role against estrogen deficiency-induced osteoporosis. Here, we evaluated the efficacy of PQQ on bone mineral density, bone microarchitecture, bone turnover and biomechanical strength in ovariectomy (OVX)-induced osteoporosis mouse model. Although dietary PQQ supplement did not affect serum E2 levels and uterine weight in OVX mice, it could prevent OVX-induced bone loss and improve bone strength by inhibiting oxidative stress, osteocyte senescence and senescence-associated secretory phenotype (SASP), subsequently promoting osteoblastic bone formation and inhibiting osteoclastic bone resorption, which was comparable to treatment with exogenous estrogen. The results from our study provide experimental evidence for the clinical use of PQQ to prevent estrogen deficiency-induced osteoporosis.

Gossypol Promotes Bone Formation in Ovariectomy-Induced Osteoporosis through Regulating Cell Apoptosis.

Osteoporosis is among the most common forms of age-related diseases, especially for females, which has been a grave public health problem. Drug therapies have shown promising outcomes to promote bone formation and bone density. This study identified a novel potential drug, gossypol, for the treatment of osteoporosis. Treatments of ovariectomy-induced osteoporosis mice with gossypol significantly increased serum osteocalcin and osteoprotegerin (OPG) levels; meanwhile they decreased serum RANKL levels. Microcomputed tomography (microCT) analysis showed that treatment of gossypol improved bone density and strength and decreased bone postyield displacement for both medullar and cortical bones. In vitro experiments also showed that gossypol increased cell viability in a time- and dose-dependent manner. Furthermore, incubation of the osteoblast MC3T3-E1 cells with gossypol inhibited cell apoptosis through intrinsic apoptotic pathway as evidenced by the Annexin V/PI assay, TUNEL assay, biochemical analysis, and western blot assays. Moreover, the classical Wnt/β-catenin signaling pathway was found to be regulated by gossypol treatments. Inhibition of Wnt/β-catenin signaling reversed the prevention effects of gossypol in osteoporosis. Our findings provided novel clues for the treatment of osteoporosis in clinic.

MiRNA profiling reveals the upregulation of osteogenesis-associated miRNAs in ovariectomy osteoporosis mice

Backgrounds: Osteoporosis is a common aging-related degenerative bone disease, particularly in postmenopausal women, that have a reduced estrogen level due to aging. Various factors have been recognized to promote osteoporosis development, such as microRNAs (miRNAs), which regulate the balance between osteogenesis and osteoclasis. Aim: This study was to profile miRNAs in the ovariectomy osteoporosis mice with miRNA profiling array, and to associate the deregulated miRNAs with osteogenesis. Materials and Methods: The authors firstly profiled, with miRNAs microarray analysis, the serum miRNAs in a mouse model with postmenopausal osteoporosis, post-ovary excision. Then they validated the dysregulated miRNAs via quantitative real-time polymerase chain reaction (qRT-PCR) method. In addition, these deregulated miRNAs were subjected to a pathway analysis. Results: It was indicated by the present results that in the ovariectomized mice, ten miRNAs were upregulated, such as miR-27a-5p, miR-26a-5p, miR-106a-5p, and miR- 133a-5p and the upregulation of miR-26a-5p, miR-133a-1-5, miR-141-5p, miR-200a-5p, and miR-205-5p were validated by the followed qRT-PCR method. In addition, the pathway analysis demonstrated that these miRNAs might inhibit the bone formation via regulating osteogenesis. Conclusions: In conclusion, the authors found the upregulation of miRNAs, which downregulates osteogenesis in a mice model of postmenopausal osteoporosis. The present findings suggest the potential inhibition by miRNAs in osteogenesis in postmenopausal osteoporosis.

Integrative Bone Metabolomics\u2014Lipidomics Strategy for Pathological Mechanism of Postmenopausal Osteoporosis Mouse Model

Osteoporosis, characterized by bone mass reduction and increased fractures, has become a global health problem that seriously affects the health of people, especially postmenopausal women; however, the current pathogenesis of postmenopausal osteoporosis (PMOP) has not been thoroughly elucidated to date. In this study, bilateral ovariectomy was performed to establish an OVX mouse model of osteoporosis. UPLC-Q-TOF-MS-based lipidomics in combination with metabolomics were used to analyze the femur tissue of osteoporosis mice. We found that 11 polar metabolites and 93 lipid metabolites were significantly changed and were involved in amino acid metabolism, nucleotide metabolism and lipid metabolism. Among the lipids, fatty acyls, glycerolipids, glycerophospholipids, sphingolipids and sterols showed robust changes. These results revealed that several metabolic disorders caused by changes in the hormone levels in OVX, especially disordered lipid metabolism, are closely related to the imbalance between bone resorption and formation and may underlie the development of PMOP. The data generated via lipidomics and metabolomics presented in this study shows good applicability and wide coverage in the construction of the metabolic profile of bone tissue. Therefore, this approach may provide the pathway focusing and data support at the metabolite level for the in-depth mechanism of PMOP.

Knockdown of TRPV4 suppresses osteoclast differentiation and osteoporosis by inhibiting autophagy through Ca2+ -calcineurin-NFATc1 pathway.

The aim of this study is to evaluate the effect of transient receptor potential vanilloid 4 (TRPV4) on osteoclast differentiation and osteoporosis, and to investigate the underlying mechanism. The results showed that TRPV4 expression and intracellular Ca2+ concentration were significantly upregulated in macrophage colony-stimulating factor (M-CSF)-stimulated and receptor activator of nuclear factor κΒ ligand (RANKL)-stimulated RAW264.7 cells. Furthermore, TRPV4 overexpression further increased the M-CSF- and RANKL-induced number of tartrate-resistant acid phosphatase (TRAP)-positive osteoclasts and expression of osteoclastogenesis-related genes (TRAP, c-Fos, and nuclear factor of activated T cells [NFATc1]), activated the Ca 2+ -calcineurin-NFATc1 signaling and increased autophagy-related proteins (light chain [LC] 3II and Beclin-1) during osteoclast differentiation. In contrast, TRPV4 knockdown exerted the opposite effects. Mechanically, inhibition of Ca 2+ -calcineurin-NFATc1 signaling by FK506 or 11R-VIVIT abrogated the TRPV4 overexpression-induced osteoclast differentiation and autophagy induction. Moreover, suppression of autophagy by 3-methyladenine attenuated the TRPV4-induced osteoclast differentiation. In addition, short hairpin RNA TRPV4-lentivirus administration significantly diminished the increased levels of several osteoclastogenesis-related genes (RANKL, TRAP, and tumor necrosis factor-α), alleviated the disturbed microarchitecture of lumbar vertebrae, restored the decreased bone mineral density, ratio of bone volume to total tissue volume, trabecular thickness, and trabecular number, and diminished the increased trabecular separation, in ovariectomy (OVX)-induced osteoporosis mice. Consistent with the in vitro data, TRPV4 knockdown significantly decreased the induced number of TRAP-positive osteoclasts, the increased LC3 and NFATc1 expression in the lumbar vertebrae of OVX mice. In conclusion, TRPV4 knockdown suppresses osteoclast differentiation and osteoporosis by inhibiting autophagy through Ca 2+ -calcineurin-NFATc1 pathway.

MicroRNA-874 targeting SUFU involves in osteoblast proliferation and differentiation in osteoporosis rats through the Hedgehog signaling pathway

Osteoporosis is widely viewed as a major public health concern, but the exact magnitude of the problem is uncertain. MicroRNAs play a key role in maintaining bone development and metabolism. This study aims to investigate the effects that microRNA-874 (miR-874) has on osteoblast proliferation and differentiation in osteoporosis rats by targeting SUFU through the Hedgehog signaling pathway. Twenty Wistar female rats were selected for following experiment, and another 20 rats were served as the normal group. Their osteogenic tissues were obtained and the positive expression of SUFU in tissues was determined. Rat osteoblasts were isolated and. The targeting relationship between SUFU and miR-874 was verified and the expression of miR-874, SUFU, Sonic Hedgehog (Shh), Ptch, Smoothened (Smo), bone morphogenetic protein (BMP2), Runx2, proliferating cell nuclear antigen (PCNA) and Bcl-2 associated X protein (Bax) were identified. Besides, cell viability apoptosis, and differentiation were confirmed respectively. Moreover, calcium nodules were observed. Overexpression of SUFU and Bax but lower expression of miR-874, Shh, Ptch, Smo, BMP2, Runx2, and PCNA were found in osteoporosis mice. Besides, elevated expression of miR-874, Shh, Ptch, Smo, BMP2, Runx2 and PCNA, as well as increased cell viability, ALP activity and calcium nodules but decreased expression of SUFU and Bax, and reduced cell apoptosis were confirmed when treated with miR-874 mimic. And it is reciprocal when miR-874 was inhibited. Our study demonstrated that through targeted inhibition of SUFU and activation of Hedgehog signaling pathway, miR-874 could promote the proliferation and differentiation of osteoblasts in osteoporosis rats.

Systemic bone loss, impaired osteogenic activity and type I muscle fiber atrophy in mice with elastase-induced pulmonary emphysema: Establishment of a COPD-related osteoporosis mouse model.

Although it is suggested that chronic obstructive pulmonary disease (COPD) and bone are related, almost all of the pathological mechanisms of COPD-related osteoporosis remain unknown. There is a mouse model showing a deterioration of bone quality after cigarette smoke exposure; however, in smoking exposure models, various factors exist that affect bone metabolism, such as smoking and body weight loss (muscle and fat mass loss). We considered it appropriate to use an elastase-induced emphysema model to exclude factors influencing bone metabolism and to investigate the influence of pulmonary emphysema on bone metabolism. The purpose of this study was to establish a COPD/emphysema-related osteoporosis mouse model by using the elastase-induced emphysema model. The lumbar vertebrae and femurs/tibiae exhibited trabecular bone loss and impaired osteogenic activity in 24-week-old male elastase-induced emphysema model mice. In addition, the model mice showed atrophy of type I muscle fibers without atrophy of type II muscle fibers. We believe that the mice described in this experimental protocol will be accepted as a COPD/emphysema-related osteoporosis mouse model and contribute to further investigations.

Hesperetin Prevents Bone Resorption by Inhibiting RANKL-Induced Osteoclastogenesis and Jnk Mediated Irf-3/c-Jun Activation.

Bone homeostasis and resorption is regulated by the proper activation of osteoclasts, whose stimulation largely depends on the receptor activator of nuclear factor κB ligand (RANKL)-RANK signaling. Herein, for the first time, we showed that interferon regulatory factor (Irf)-3 was intimately involved in RANKL-induced osteoclast formation. In addition, hesperetin (Hes) derived from citrus fruit could inhibit RANKL-induced osteoclast differentiation and maturation among three types of osteoclast precursors with inhibited formation of F-actin rings and resorption pits on bone slices. More importantly, by using SP600125, a selective Jnk inhibitor, we showed that Hes was able to significantly attenuate the Jnk downstream expression of Irf-3 and c-Jun, thereby inactivating NF-κB/MAPK signaling and transcriptional factor NFATc-1, leading to suppression of osteoclast-specific genes, which resulted in impaired osteoclastogenesis and functionality. An ovariectomized (OVX) osteoporosis mouse model demonstrated that Hes could increase trabecular bone volume fractions (BV/TV), trabecular thickness, and trabecular number, whereas it decreased trabecular separation in OVX mice with well-preserved trabecular bone architecture and decreased levels of TRAP-positive osteoclasts. This is further evidenced by the diminished serum expression of bone resorption marker CTX and enhanced production of osteoblastic ALP in vivo. Taken together, these results suggested that Hes could inhibit Jnk-mediated Irf-3/c-Jun activation, thus attenuating RANKL-induced osteoclast formation and function both in vitro and in vivo.

Protective Effects of 2,3,5,4'-Tetrahydroxystilbene-2-O-β-d-glucoside on Ovariectomy Induced Osteoporosis Mouse Model.

2,3,5,4′-Tetrahydroxystilbene-2-O-β-d-glucoside (TSG), an active polyphenolic component of Polygonum multiflorum, exhibits many pharmacological activities including antioxidant, anti-inflammation, and anti-aging effects. A previous study demonstrated that TSG protected MC3T3-E1 cells from hydrogen peroxide (H2O2) induced cell damage and the inhibition of osteoblastic differentiation. However, no studies have investigated the prevention of ovariectomy-induced bone loss in mice. Therefore, we investigated the effects of TSG on bone loss in ovariectomized mice (OVX). Treatment with TSG (1 and 3 μg/g; i.p.) for six weeks positively affected body weight, uterine weight, organ weight, bone length, and weight change because of estrogen deficiency. The levels of the serum biochemical markers of calcium (Ca), inorganic phosphorus (IP), alkaline phosphatase (ALP), and total cholesterol (TCHO) decreased in the TSG-treated mice when compared with the OVX mice. Additionally, the serum bone alkaline phosphatase (BALP) levels in the TSG-treated OVX mice were significantly increased compared with the OVX mice, while the tartrate-resistant acid phosphatase (TRAP) activity was significantly reduced. Furthermore, the OVX mice treated with TSG showed a significantly reduced bone loss compared to the untreated OVX mice upon micro-computed tomography (CT) analysis. Consequently, bone destruction in osteoporotic mice as a result of ovariectomy was inhibited by the administration of TSG. These findings indicate that TSG effectively prevents bone loss in OVX mice; therefore, it can be considered as a potential therapeutic for the treatment of postmenopausal osteoporosis.

The effect of human-like collagen calcium complex on osteoporosis mice

The objective of this study was to assess the effect of a modified human-like collagen calcium complex on osteoporosis mice. BHK (Baby Hamster Kidney) cells were used to compare the cytotoxicity of different calcium reagents with the MTT test. Six-week-old male mice (n = 80) were randomly divided into eight groups: a blank group (blank), control group (control), human-like collagen calcium group (HLC-Ca), thiolated human-like collagen calcium group (SH-HLC-Ca), phosphorylated human-like collagen calcium group (Pi-HLC-Ca), gluconate group (Glc-Ca), calcium carbonate group (CaCO3) and D-cal group (B). A systematic analysis of the results available in vivo after 3 months of treatment was presented. The effects of several Ca supplements on osteoporosis mice were investigated by detecting serum calcium, alkaline phosphate activity (ALP), bone hydroxyproline (BHP) and bone mineral density (BMD). The results proved that the BMD and BHP of osteoporosis mice were significantly increased in the Pi-HLC-Ca group, while serum calcium and ALP were decreased. Therefore, Pi-HLC-Ca is likely a good calcium supplement for clinical applications. In this review, the advantage of Pi-HLC-Ca in preventing and delaying osteoporosis is highlighted. In addition to the current progress, further investigations are necessary to reveal the relative influences of collagen and calcium proportions on the long-term clinical effects of osteoporosis.

Effect of Lipocalin-2 gene on osteogenic differentiation of bone marrow mesenchymal stem cells and bone strength of osteoporosis mice model

Objective To investigate the role and mechanism of Lipocalin-2 gene in osteoporosis. Methods Reverse transcriptase-polymerase chain reaction (RT-PCR) assay and compared patients with osteoporosis (n=18) and non osteoporosis patients (n=18) expression of Lipocalin-2 blood samples by mRNA; mouse bone marrow mesenchymal stem cells with Lipocalin-2 gene, alkaline phosphatase (ALP) staining and alizarin red staining to detect cell osteogenic differentiation of Western cells, blotting detection of bone differentiation related gene expression of bone; a mouse model of osteoporosis, osteoporosis by mouse Lipocalin-2 gene, micro-CT detection of mouse tibia trabecular bone volume, the mechanical properties of the femur bending test. Results The relative expression of mRNA in patients with osteoporosis (1.693±0.359) Lipocalin-2 was higher than that of non osteoporotic group (1.108±0.234), P=0.019. Moreover, the relative expression of Lipocalin-2 mRNA in osteoporotic patients with osteoporotic fracture history (n=10, 2.172±0.624) is higher than that in patients without fracture history (n=8, 1.473±0.336). The protein level of Runx2 and osteocalcin (OCN) and the relative expression of mRNA in the bone marrow mesenchymal stem cells (BMSCs) osteogenic differentiation gene of Lipocalin-2 mice were higher than those in the control group. In the Lipocalin-2 group [(812.78±25.36) N/mm], the femoral flexural strength was higher than that in the control group [(744.36±31.54) N/mm], while in the LCN2-small interfering RNA (siRNA) group [(19.69±3.69) μm2], the trabecular area in the proximal tibia was larger than that in the control group [(14.77±4.25) μm2]. Conclusion The expression of Lipocalin-2 is increased in patients with osteoporosis, and the ability of osteogenic differentiation of stem cells is enhanced after downregulation of Lipocalin-2 gene. Down regulation of Lipocalin-2 gene can improve the degree of osteoporosis in mice, and its mechanism is related to Runx2 and OCN. Key words: Osteoporosis; Bone marrow mesenchymal stem cells; Human lipid carrier protein 2; Osteogenic differentiation

Cyperenoic acid suppresses osteoclast differentiation and delays bone loss in a senile osteoporosis mouse model by inhibiting non-canonical NF-\u03baB pathway

Cyperenoic acid is a terpenoid isolated from the root of a medicinal plant Croton crassifolius with a wide range of biological activities. In this study, the effects of cyperenoic acid on osteoclast differentiation were investigated both in vitro and in vivo using receptor activator of nuclear factor-κB ligand (RANKL)-induced bone marrow-derived osteoclasts and senescence-accelerated mouse prone 6 (SAMP6). Cyperenoic acid significantly suppressed RANKL-induced osteoclast differentiation at the concentrations with no apparent cytotoxicity. The half maximum inhibitory concentration (IC50) for osteoclast differentiation was 36.69 μM ± 1.02. Cyperenoic acid treatment evidently reduced the expression of two key transcription factors in osteoclast differentiation, NFATc1 and c-Fos. Detailed signaling analysis revealed that cyperenoic acid did not affect MAPK pathways and canonical NF-κB pathway but impaired activation of p100/p52 in the non-canonical NF-κB pathway upon RANKL stimulation. Moreover, the expression of osteoclast-related genes, nfatc1, ctsk, irf8, acp5 and cfos were disrupted by cyperenoic acid treatment. The bone resorption activity by cyperenoic acid-treated osteoclasts were impaired. In a senile osteoporosis mouse model SAMP6, mice fed on diet supplemented with cyperenoic acid showed delay in bone loss, compared to the control. Taken together, plant-derived cyperenoic acid shows great potential as therapeutic agent for osteoporosis.

Omentin-1 prevents inflammation-induced osteoporosis by downregulating the pro-inflammatory cytokines

Osteoporosis is a frequent complication of chronic inflammatory diseases and increases in the pro-inflammatory cytokines make an important contribution to bone loss by promoting bone resorption and impairing bone formation. Omentin-1 is a newly identified adipocytokine that has anti-inflammatory effects, but little is known about the role of omentin-1 in inflammatory osteoporosis. Here we generated global omentin-1 knockout (omentin-1−/−) mice and demonstrated that depletion of omentin-1 induces inflammatory bone loss-like phenotypes in mice, as defined by abnormally elevated pro-inflammatory cytokines, increased osteoclast formation and bone tissue destruction, as well as impaired osteogenic activities. Using an inflammatory cell model induced by tumor necrosis factor-α (TNF-α), we determined that recombinant omentin-1 reduces the production of pro-inflammatory factors in the TNF-α-activated macrophages, and suppresses their anti-osteoblastic and pro-osteoclastic abilities. In the magnesium silicate-induced inflammatory osteoporosis mouse model, the systemic administration of adenoviral-delivered omentin-1 significantly protects from osteoporotic bone loss and inflammation. Our study suggests that omentin-1 can be used as a promising therapeutic agent for the prevention or treatment of inflammatory bone diseases by downregulating the pro-inflammatory cytokines.

In vivo and in vitro effects of PTH1-34 on osteogenic and adipogenic differentiation of human bone marrow-derived mesenchymal stem cells through regulating microRNA-155.

This study aimed to investigate the effect of parathyroid hormone (PTH1-34) on osteogenic and adipogenic differentiation of hBMSCs by the regulation of miR-155. A total of 36 adult volunteers were selected in this study. Effects of PTH1-34 on the proliferation of hBMSCs and miR-155 expression were investigated using a MTT assay. The hBMSCs were divided into blank, PTH1-34, miR-155 mimic, miR-155 mimic negative control (NC), miR-155 inhibitor, miR-155 inhibitor NC, PTH1-34 + miR-155 mimic, PTH1-34 + miR-155 inhibitor, and NPS R-568 groups. Postmenopausal osteoporosis (PMOP) mouse models were established by ovariectomy (OVX) and divided into ten groups. The RT-qPCR and Western blotting assay were carried out to detect the expression of osteogenesis/adipogenic-related genes and miR-155, and osteogenesis/adipogenic-related proteins. PTH1-34 could promote hBMSCs proliferation and inhibit miR-155 expression in a dose-dependent manner. Compared with the blank control group, expressions of Runx2, and BSP was up-regulated in the PTH1-34 and miR-155 inhibitor groups, while expressions of miR-155, PPAR-γ, lipoprotein lipase (LPL), fatty acid binding protein 4 (Fabp4), adiponectin, and CCAAT/enhancer binding protein α (C/EBPα) were down-regulated. In the in vivo experiment, compared with the OVX group, the BMD and expressions of Runx2 and BSP was up-regulated in the PTH1-34, miR-155 inhibitor, and PTH1-34 + miR-155 inhibitor groups, while expressions of PPAR-γ, LPL, Fabp4, adiponectin, and C/EBPα were down-regulated. The miR-155 mimic and NPS R-568 groups followed opposite trends. PTH1-34 could promote the osteogenic differentiation and inhibits adipogenic differentiation of hBMSCs through down-regulating miR-155 in PMOP mice.

Dysregulation of 5-hydroxytryptamine 6 receptor accelerates maturation of bone-resorbing osteoclasts and induces bone loss.

Rationale: Characterizing the regulation of bone-resorbing osteoclasts is central to the understanding of the pathogenesis and treatment of bone diseases, such as osteoporosis and periodontitis. 5-hydroxytryptamine (5-HT) has drawn considerable attention for its role in bone; however, it remains unknown whether the intracellular signaling of 5-HT receptors (5-HTRs) is linked to any of the regulatory mechanisms in osteoclasts. Herein, we report 5-HT6R to be a key regulatory receptor for osteoclastogenesis.Methods: In order to explore the critical role of 5-HT6R in bone-resorbing osteoclasts, in vitro experiments were performed using mouse whole bone marrow cells isolated from femora and tibiae and In vivo animal experiments were performed using 5-HT6R-deficient (5-HT6RKO-/-) mice, bone resorption mice model, and osteoporosis mice model.Results: Compared to other 5HTRs, activation of 5-HT6R relatively increased TRAP (tartrate-resistant acid phosphatase) activity during osteoclastogenesis. 5-HT6RKO(-/-) mice and 5-HT6RKO(-/-) osteoclast lineages presented with an abnormal phenotype and impaired osteoclastogenesis and impaired osteoclastogenesis. Activation of 5-HT6R increased the number of TRAP-positive multinuclear osteoclasts, actin ring formation, and expression of early osteoclast markers with osteoclast lineage commitment. Intracellular 5-HT6R signaling was found to be linked to RhoA GTPase activation and was involved in the maturation of osteoclasts. This signaling pathway also showed enhanced bone destruction after lipopolysaccharide (LPS) administration in mice. Furthermore, inhibition of 5-HT6R-mediated RhoA GTPase signaling protected against ovariectomy(OVX)-induced bone loss in mice.Conclusion: Taken together, our findings place the 5-HT6R system in a new context of osteoclast lineages in both an in vitro and in vivo system, and also it may offer a novel molecular target for the treatment of bone diseases.

Icariin ameliorates dexamethasone‑induced bone deterioration in an experimental mouse model via activation of microRNA‑186 inhibition of cathepsin K.

The present study aimed to investigate bone deterioration in glucocorticoid-induced osteoporosis (GIOP) mice, and the anti-osteoporosis effect and underlying molecular mechanism of icariin. Dexamethasone (DSM) treatment was demonstrated to facilitate the induction of hypercalciuria in GIOP mice. Icariin treatment reversed the dexamethasone (DXM)-induced disequilibrium of calcium homeostasis and bone resorption, and increased serum alkaline phosphatase, tartrate resistant acid phosphatase, osteocalcin and deoxypyridinoline. Haematoxylin and eosin staining revealed an increase in disconnections and separation in the trabecular bone network of the tibial proximal metaphysis, in the GIOP group. Icariin treatment reversed the DXM-induced trabecular deleterious effects, and stimulated bone remodeling in GIOP mice. Furthermore, the results demonstrated that the mRNA and protein expression of cathepsin K were significantly increased in GIOP mice, compared with the control group. Icariin treatment may suppress the expression of cathepsin K in the tibia of GIOP mice. The levels of microRNA (miR)-186 were markedly reduced in the tibia of GIOP mice compared with control group; however, this was inhibited by icariin treatment. Bioinformatics analysis demonstrated that miR-186 regulates cathepsin K via binding to the upstream 3′-untranslated region. Furthermore, transfection with miR-186 mimics resulted in inhibition of cathepsin K expression, whereas miR-186 inhibitors facilitated cathepsin K expression in osteoclasts. In conclusion, the present study demonstrated the protective effects of icariin against bone deteriorations in the experimental GIOP mice, and the underlying mechanism was mediated, at least partially, via activation of miR-186-mediated suppression of cathepsin K. These results provide evidence to support the use of icariin as a therapeutic approach in the management of glucocorticoid-induced bone loss, and the disequilibrium of calcium homeostasis.

MiR-455-3p activates Nrf2/ARE signaling via HDAC2 and protects osteoblasts from oxidative stress

BackgroundThe important role of miR-455-3p in the pathogenesis of bone metabolism associated diseases is gradually emerging. This study aims to ascertain the involvement of miR-455-3p and its underlying mechanisms in osteoporosis. MethodsThe osteoblast cell lines MC3T3-E1 was treated with ferric ammonium citrate (FAC) to mimic a pathological environment for osteoporosis. The cytotoxic effect of iron overload was assessed by proliferation, apoptosis and oxidative stress of osteoblasts using commercial kits. Molecular biological methods, including qRT-PCR analysis, cell transfection and luciferase reporter assays were used to explain the role of miR-455-3p and its potential mechanisms in osteoblast apoptosis. ResultsFAC dramatically inhibited the proliferation of osteoblast cells MC3T3-E1 but increased the apoptosis. We also observed that FAC significantly down-regulated miR-455-3p in MC3T3-E1 cells but enhanced HDAC2 protein level. Moreover, miR-455-3p overexpression eliminated the effects of iron overload on osteoblast cell proliferation, apoptosis and oxidative stress. In addition, miR-455-3p regulated osteoblast cell proliferation, apoptosis and oxidative stress through regulating HDAC2-Nrf2/ARE signaling pathway. MiR-455-3p overexpression alleviated the oxidative stress injury in osteoporosis mice. ConclusionOur results demonstrated that miR-455-3p activated Nrf2/ARE signal pathway through suppressing Keap1 via negative regulating HDAC2 protein level, thereby suppressing oxidative stress and promoting osteoblasts growth.