Systematic analysis of lncRNAs, miRNAs and mRNAs for the identification of biomarkers for osteoporosis in the mandible of ovariectomized mice

Advances of long non-coding RNAs in osteoclast differentiation and osteoporosis

INTRODUCTION

Osteoclasts, which are responsible for bone resorption, are specialized multinucleated cells generated from monocyte/macrophage progenitor cells or hematopoietic stem cells (HSCs). Physiological bone remodeling can become pathological, such as osteoporosis, when osteoclastogenesis is out of balance. Thousands of long noncoding RNAs (lncRNAs) influence important molecular and biological processes. Recent research has revealed gene expression regulation function that numerous lncRNAs regulate nuclear domain organization, genome stability. Furthermore, the research of lncRNAs has substantial clinical implications for the treatment of existing and new diseases.

AREAS COVERED

In this review, we gather the most recent research on lncRNAs and their potential for basic research and clinical applications in osteoclast and osteoporosis. We also discuss the findings here in order to fully understand the role of lncRNAs in osteoclast differentiation and osteoporosis, as well as to provide a solid basis for future research exploring associated mechanisms and treatments.

EXPERT OPINION

LncRNA has been considered as an important role in the regulation of osteoclast differentiation and osteoporosis. It is exciting to investigate pathophysiological processes in osteoporosis and the therapeutic potential of lncRNAs. We hope that this review will offer promising prospects for the development of precision and individualized approaches to treatment.

Association of life's essential 8 and risk of fragility fractures: A large cohort study

Cardiovascular health (CVH) score is not only associated with cardiovascular diseases, but also some disorders in other systems. This study aims to investigate the association between CVH score and the risk of fragility fractures. The analysis enrolled 89,464 participants at baseline in Kailuan study initiated in 2006-2007. All participants were then followed up every 2 years and the incidence of fragility fractures was recorded annually. A total CVH score was classified as low (0-49 points), moderate (50-79 points), and ideal (80-100 points). The primary outcome was incident fragility fractures before December 31, 2021. Kaplan-Meier was used to estimate cumulative incidence. Multivariable adjusted Cox proportional hazards regression models and time-dependent Cox hazards regression models were used to estimate fragility fracture hazard ratios (aHR) and 95% confidence intervals (95% CI). After 13.98 ± 2.84 years of follow-up, a total of 1534 cases of fragility fractures were identified, with an incidence density of 1.23 per 1000 person-years. Compared with the low CVH group, the risk of fragility fractures was significantly lower in moderate (aHR = 0.78, 95% CI: 0.66-0.92) and ideal CVH groups (aHR = 0.65, 95% CI: 0.51-0.83), particularly in the age <60 group (aHR = 0.72, 95% CI: 0.59-0.88; aHR= 0.55, 95% CI: 0.41-0.73, respectively). Time-dependent Cox hazards regression models, sensitivity analysis, and death competition model confirmed the reliability of these findings. The ideal CVH score is associated with a decreased risk of fragility fractures. With the increase of CVH score, the risk of fragility fracture decreases.

Inhibiting KCNMA1-AS1 promotes osteogenic differentiation of HBMSCs via miR-1303/cochlin axis

OBJECTIVE

Osteoporosis is a progressive systemic skeletal disorder. Multiple profiling studies have contributed to characterizing biomarkers and therapeutic targets for osteoporosis. However, due to the limitation of the platform of miRNA sequencing, only a part of miRNA can be sequenced based on one platform.

MATERIALS AND METHODS

In this study, we performed miRNA sequencing in osteoporosis bone samples based on a novel platform Illumina Hiseq 2500. Bioinformatics analysis was performed to construct osteoporosis-related competing endogenous RNA (ceRNA) networks. Gene interference and osteogenic induction were used to examine the effect of identified ceRNA networks on osteogenic differentiation of human bone marrow-derived mesenchymal stem cells (HBMSCs).

RESULTS

miR-1303 was lowly expressed, while cochlin (COCH) and KCNMA1-AS1 were highly expressed in the osteoporosis subjects. COCH knockdown improved the osteogenic differentiation of HBMSCs. Meanwhile, COCH inhibition compensated for the suppression of osteogenic differentiation of HBMSCs by miR-1303 knockdown. Further, KCNMA1-AS1 knockdown promoted osteogenic differentiation of HBMSCs through downregulating COCH by sponging miR-1303.

CONCLUSIONS

Our findings suggest that the KCNMA1-AS1/miR-1303/COCH axis is a promising biomarker and therapeutic target for osteoporosis.

LncRNAs in neuropsychiatric disorders and computational insights for their prediction

Long non-coding RNAs (lncRNAs) are 200 nucleotide extended transcripts that do not encode proteins or possess limited coding ability. LncRNAs epigenetically control several biological functions such as gene regulation, transcription, mRNA splicing, protein interaction, and genomic imprinting. Over the years, drastic progress in understanding the role of lncRNAs in diverse biological processes has been made. LncRNAs are reported to show tissue-specific expression patterns suggesting their potential as novel candidate biomarkers for diseases. Among all other non-coding RNAs, lncRNAs are highly expressed within the brain-enriched or brain-specific regions of the neural tissues. They are abundantly expressed in the neocortex and pre-mature frontal regions of the brain. LncRNAs are co-expressed with the protein-coding genes and have a significant role in the evolution of functions of the brain. Any deregulation in the lncRNAs contributes to disruptions in normal brain functions resulting in multiple neurological disorders. Neuropsychiatric disorders such as schizophrenia, bipolar disease, autism spectrum disorders, and anxiety are associated with the abnormal expression and regulation of lncRNAs. This review aims to highlight the understanding of lncRNAs concerning normal brain functions and their deregulation associated with neuropsychiatric disorders. We have also provided a survey on the available computational tools for the prediction of lncRNAs, their protein coding potentials, and sub-cellular locations, along with a section on existing online databases with known lncRNAs, and their interactions with other molecules.

Effects of exercise on the expression of long non-coding RNAs in the bone of mice with osteoporosis

Physical activity or exercise are known to promote bone formation and decrease bone resorption to maintain skeletal and bone health both in animal models and in humans with osteoporosis. Previous studies have indicated that long non-coding RNAs (lncRNAs) are able to regulate bone metabolism. Therefore, the present study aimed to evaluate whether lncRNAs responded to exercise by regulating the balance of bone metabolism in order to prevent osteoporosis. To meet this end, ovariectomized mice were used in the present study to establish an osteoporosis model. The exercise treatment groups were subjected to 9 weeks of treadmill running exercise in 4 weeks of the operation was performed Femurs were collected to measure bone mineral density, bone mass, bone formation and resorption. The expression levels of lncRNAs were subsequently measured using microarray and gene function analyses. The pairwise comparison results [ovariectomy (OVX) vs. OVX + exercise (EX); OVX vs. SHAM; SHAM vs. SHAM + EX; OVX + EX vs. SHAM + EX] of the gene microarray analysis revealed that the expression of 2,424 lncRNAs (1718 upregulated and 706 downregulated) were significantly altered in the mouse femurs following treadmill running. Gene Ontology (GO) analysis, incorporating the GO annotations ‘biological processes’, ‘molecular function’ and ‘cellular components’, of osteoporosis revealed that the VEGF, mTOR and NF-κB signaling pathways were potential targets of the lncRNAs. Moreover, it was possible to predict the target microRNAs (miRNAs) of six lncRNAs (LOC105246953, LOC102637959, NONMMUT014677, NONMMUT027251, ri|D130079K21|PX00187K16|1491 and NONMMUT006626), which suggested that the underlying mechanism by which lncRNAs respond to exercise involved bone regulation via lncRNA-miRNA sponge adsorption. Overall, these results suggested that the treadmill running exercise did regulate lncRNA expression in the bone, and that this was involved in the prevention of osteoporosis.

Evaluation of the effect of vitamin D3 on mandibular condyles in an ovariectomized mouse model: a micro-CT study

BACKGROUND

This study aimed to investigate the effect of ovariectomy and vitamin D3 on bone microstructure; this effect was examined in three regions of interest at one femoral and two mandibular sampling sites bone in an ovariectomized mouse model.

METHODS

Thirty-six week-old female mice were randomly divided into three groups: 10 subjects were given oral cholecalciferol (vitamin D3) daily for 6 weeks after undergoing bilateral ovariectomy (D3 group), while 10 ovariectomized subjects (OVX) and 10 subjects who underwent a sham operation (SHAM) received peanut oil daily during the investigation. After extermination, the left hemimandible and femur were removed and scanned by micro-CT. The bone micromorphology parameters were analyzed and the BMD was calculated.

RESULTS

The bone volume fraction (BV/TV) was significantly lower in the trabecular bone of the mandibular condyle in the OVX group than in the SHAM and D3 groups. Also there was a significant difference between the SHAM and D3 groups. The specific bone surface (BS/BV) was significantly higher in the OVX and D3 groups than in the SHAM group. Trabecular thickness (Tb.Th) was significantly higher in the SHAM group, and the trabecular bone pattern factor (Tb.Pf) was significantly higher in the OVX group than in the other two groups. Bone mineral density (BMD) of the femur and the mandible was significantly lower in the OVX group than in the SHAM and D3 groups.

CONCLUSIONS

Our results show that ovariectomy causes a significantly weaker bone microstructure in the mandibular condyle, where the protective effect of vitamin D3 resulted in a partial resorption.

Effects of miRNAs, lncRNAs and circRNAs on osteoporosis as regulatory factors of bone homeostasis (Review)

Osteoporosis is a common metabolic bone disorder typically characterized by decreased bone mass and an increased risk of fracture. At present, the detailed molecular mechanism underlying the development of osteoporosis remains to be elucidated. Accumulating evidence shows that non-coding (nc)RNAs, such as microRNAs (miRNAs), long ncRNAs (lncRNAs) and circular RNAs (circRNAs), play significant roles in osteoporosis through the post-transcriptional regulation of gene expression as regulatory factors. Previous studies have demonstrated that ncRNAs participate in maintaining bone homeostasis by regulating physiological and developmental processes in osteoblasts, osteoclasts and bone marrow stromal cells. In the present review, the latest research investigating the involvement of miRNAs, lncRNAs and circRNAs in regulating the differentiation, proliferation, apoptosis and autophagy of cells that maintain the bone microenvironment in osteoporosis is summarized. Deeper insight into the aspects of osteoporosis pathogenesis involving the deregulation of ncRNAs could facilitate the development of therapeutic approaches for osteoporosis.

Management of systemic risk factors ahead of dental implant therapy: A beard well lathered is half shaved

As the most successful therapy for missing teeth, dental implant has become increasingly prevalent around the world. A lot of papers have reported diverse local risk factors affecting the success and survival rate of dental implants, either for a short or a long period. However, there are also many types of systemic disorders or relatively administrated medicine that may jeopardize the security and success of dental implant treatment. Additionally, the coronavirus disease 2019 pandemic also poses a challenge to dental implant clinicians. Some of these risk factors are clinically common but to some extent unfamiliar to dentists, thus optimal measurements are often lacking when they occur in dental clinics. In this review, we analyze potential systemic risk factors that may affect the success rate of dental implants. Some of them may affect bone mineral density or enhance the likelihood of local infection, thus impeding osseointegration. Others may even systemically increase the risk of the surgery and threaten patients' life. In order to help novices receive high-risk patients who need to get dental implant treatment in a more reasonable way, we accordingly review recent research results and clinical experiments to discuss promising precautions, such as stopping drugs that impact bone mineral density or the operation, and addressing any perturbations on vital signs.

Estrogen prevents cellular senescence and bone loss through Usp10-dependent p53 degradation in osteocytes and osteoblasts: the role of estrogen in bone cell senescence

Estrogens play multiple roles in maintaining skeletal homeostasis by regulating many physiological processes in bone cells. Recently, cellular senescence in bone cells, especially in osteocytes, has been demonstrated to be a pivotal factor in bone loss. However, whether and how estrogen mediates cellular senescence in bone cells remains unknown. Here, we show that estrogen is negatively correlated with p53-related cellular senescence, primarily through the regulation of p53 protein levels, both in vivo and in vitro. Further study confirmed that estrogen attenuated the nuclear import of p53 and accelerated p53 degradation in osteocyte-like MLO-Y4 cells and osteoblastic MC3T3-E1 cells. A screen of p53-related ubiquitinating/deubiquitinating enzymes indicated that estrogen induced the degradation of p53 through the regulation of Usp10, a deubiquitinase that is directly linked to p53. Usp10 inhibition attenuated H₂O₂-induced senescence in MLO-Y4 cells, as indicated by p53/p21 quantification, a senescence-associated β-galactosidase (SA-β-gal) assay, and p53 localization visualization with a confocal microscope. Usp10 overexpression abolished the estrogen-mediated regulation of p53 and the downstream transcriptional gene p21. The injection of ovariectomized (OVX) mice with Spautin-1, a Usp10 inhibitor, inhibited the expression of p53 and the transcription of downstream senescence markers, as well as promoted bone mass recovery. Taken together, our study unveils the regulatory function of estrogen in the prevention of cellular senescence through the regulation of Usp10, thereby accelerating the degradation of senescent factor p53 and inhibiting its nuclear import.

Down-regulated microRNA-199a-3p enhances osteogenic differentiation of bone marrow mesenchymal stem cells by targeting Kdm3a in ovariectomized rats

Osteoporosis is a prevalent systemic skeletal disorder entailing bone fragility and increased fracture risk, often emerging in post-menopausal life. Emerging evidence implicates the dysregulation of microRNAs (miRNAs or miRs) in the progression of osteoporosis. This study investigated the effect of miR-199a-3p on osteoporosis and its underlying mechanism. We first examplished an ovariectomized (OVX)-induced rat osteoporosis model, and then isolated mesenchymal stem cells (MSCs) from bone marrow of the model rats. The overexpression and knock down of miR-199a-3p were conducted in OVX rats and MSCs to verify the role of miR-199a-3p on MSC differentiation. Calcium nodules were measured using alizarin red S (ARS) staining. RT-qPCR and Western blot assay were performed to measure the expression of miR-199a-3p, Kdm3a and osteogenic differentiation-related markers in rat tissues and cells. The correlation between miR-199a-3p and Kdm3a was confirmed using dual-luciferase reporter assay. The enrichment of Kdm3a at the Erk2 and Klf2 promoter was assessed using chromatin immunoprecipitation (ChIP) assay. Isolated MSCs were positive for CD29, CD44, CD90, and CD45, suggesting successful isolation of MSCs. There was increased expression of miR-199a-3p and inhibited osteogenic differentiation in OVX rats. Kdm3a was negatively targeted by miR-199a-3p. Our results also demonstrated that Kdm3a elevated the expression of Erk2 and Erk2 by promoting Erk2 and Klf2 demethylation, which further contributed to osteogenic differentiation. Overall, our results revealed a regulatory network of miR-199a-3p in osteogenic differentiation, highlighting miR-199a-3p as a potential target for therapeutic interventions in osteoporosis.

lncRNA WT1-AS is upregulated in osteoporosis and regulates the apoptosis of osteoblasts by interacting with p53

In cervical cancer, cellular tumor antigen p53 (p53) interacts with long non-coding WT1 antisense RNA (WT1-AS) and this protein serves an important role in osteoporosis. The present study aimed to investigate the role of WT1-AS in osteoporosis. WT1-AS was upregulated in the plasma of patients with osteoporosis and was positively correlated with p53 expression. Altered expression of WT1-AS and p53 separated patients with osteoporosis from healthy controls. Expression levels of WT1-AS and p53 decreased with prolonged treatment. In osteoblasts, WT1-AS overexpression resulted in increased p53 expression, while WT1-AS small interfering RNA (siRNA) silencing resulted in decreased p53 expression. In addition, WT1-AS overexpression resulted in increased apoptosis rate, while WT1-AS siRNA silencing resulted in decreased apoptosis rate in osteoblasts. p53 overexpression attenuated the effects of WT1-AS siRNA silencing on cell apoptosis. Therefore, WT1-AS was upregulated during osteoporosis and regulated the apoptosis of osteoblasts by interacting with p53.

The Roles of LncRNAs in Osteogenesis, Adipogenesis and Osteoporosis

BACKGROUND

Osteoporosis (OP) is the most common bone disease, which is listed by the World Health Organization (WHO) as the third major threat to life and health among the elderly. The etiology of OP is multifactorial, and its potential regulatory mechanism remains unclear. Long non-coding RNAs (LncRNAs) are the non-coding RNAs that are over 200 bases in the chain length. Increasing evidence indicates that LncRNAs are the important regulators of osteogenic and adipogenic differentiation, and the occurrence of OP is greatly related to the dysregulation of the bone marrow mesenchymal stem cells (BMSCs) differentiation lineage. Meanwhile, LncRNAs affect the occurrence and development of OP by regulating OP-related biological processes.

METHODS

In the review, we summarized and analyzed the latest findings of LncRNAs in the pathogenesis, diagnosis and related biological processes of OP. Relevant studies published in the last five years were retrieved and selected from the PubMed database using the keywords of LncRNA and OP.

RESULTS/CONCLUSION

The present study aimed to examine the underlying mechanisms and biological roles of LncRNAs in OP, as well as osteogenic and adipogenic differentiation. Our results contributed to providing new clues for the epigenetic regulation of OP, making LncRNAs the new targets for OP therapy.

The miRNA-15b/USP7/KDM6B axis engages in the initiation of osteoporosis by modulating osteoblast differentiation and autophagy

Osteoporosis is a metabolic disease that results from oxidative stress or inflammation in renal disorders. microRNAs (miRNAs) are recently implicated to participate in osteoporosis, but the mechanism remains largely unexplored. Herein, we aimed to explore the potential role of miR-15b in osteoblast differentiation and autophagy in osteoporosis. We established osteoporosis models through ovariectomy and determined that miR-15b was highly expressed whereas USP7 and KDM6B were poorly expressed in tissue of osteoporosis mice. Treatment of silenced miR-15b resulted in the elevation of decreased bone mineral density (BMD), the maximum elastic stress and the maximum load of osteoporosis mice. In osteoblasts, miR-15 overexpression decreased proliferation but suppressed the cell differentiation and autophagy, accompanied with decreased expression of USP7. Mechanistically, miR-15 bound and inhibited USP7 expression, while overexpression of USP7 promoted autophagy of osteoblasts. USP7, importantly, strengthened the stability of KDM6B and promoted KDM6B expression. MG132 protease inhibitor increased KDM6B and USP7 expression in osteoblasts. Silencing of KDM6B reversed the promoting effect on autophagy and proliferation induced by overexpression of USP7. Taken altogether, miR-15b inhibits osteoblast differentiation and autophagy to aggravate osteoporosis by targeting USP7 to regulate KDM6B expression.

Serum MicroRNA Differences Between Fracture in Postmenopausal Women with and without Diabetes

OBJECTIVE

To screen serum microRNAs (miRNAs) which could discriminate fracture status in postmenopausal women with or without diabetes.

METHODS

The miRNA expression profile dataset GSE70318 was downloaded from Gene Expression Omnibus (GEO) database. This dataset composed of 74 samples, among these, 55 postmenopausal women was selected for bioinformatics analysis, including 19 osteoporotic fracture patients with type-2 diabetes, 19 osteoporotic fracture patients without type-2 diabetes, and 17 healthy control subjects. These samples were divided into two groups: fracture patients with diabetes vs healthy subjects (FH group) and fracture patients without diabetes vs healthy subjects (DFH group). Then, the differentially expressed miRNA (DEMs) in FH group and DFH group were respectively identified. The target genes of DEMs were predicted, followed by functional enrichment analysis. Furthermore, DEMs related to long non-coding RNAs (lncRNAs) were screened, and DEMs-lncRNA-target genes network was constructed. Subsequently, principal component analysis (PCA) of DEMs was performed to further explore the expression characteristics of the selected miRNAs in different types of fracture samples. Finally, the expression level of significant DEMs was calculated by quantitative real-time polymerase chain reaction (qPCR) to verify the accuracy of the results of bioinformatics analysis.

RESULTS

A total of 18 and 23 DEMs were identified in FH and DFH groups, respectively. Gene ontology (GO) analysis showed that genes in FH group were significantly enriched in regulation of transcription (GO: 0045449) and genes in DFH group were mainly enriched in cellular response to hormone stimulus (GO: 0032870). Meanwhile, pathway analysis indicated that genes in FH group were primarily enriched in T cell receptor signaling pathway (hsa04660) and genes in DFH group were mainly implicated in neurotrophin-signaling pathway (hsa04722). Moreover, the miRNA-lncRNA analysis revealed that miR-155-5p regulated by lncRNA MIR155HG was up-regulated in FH group; in addition, the miR-181c was significantly up-regulated and miR-375 was observably down-regulated in DFH group. Furthermore, PCA analysis suggested that the screened miRNAs were able to differentiate these two types of fractures in postmenopausal women. The miR-181c and miR-375 might be regarded as potential predictors for fracture, while miR-155-5p might be a candidate diagnostic biomarker for diabetic fracture. Finally, the results of qPCR were consistent with that of microarray data.

CONCLUSIONS

Overall, these three miRNAs might be regarded as potential diagnostic biomarkers to discriminate fracture status in postmenopausal women with and or without diabetes, and they served a putative role in the pathogenesis of these two diseases. However, these findings were only observed in serum samples and further clinical trials are urgently demanded to validate our results.

LncRNA, Important Player in Bone Development and Disease

BACKGROUND

Bone is an important tissue and its normal function requires tight coordination of transcriptional networks and signaling pathways, and many of these networks/ pathways are dysregulated in pathological conditions affecting cartilage and bones. Long non-coding RNA (lncRNA) refers to a class of RNAs with a length of more than 200 nucleotides, lack of protein-coding potential, and exhibiting a wide range of biological functions. Although studies on lcnRNAs are still in their infancy, they have emerged as critical players in bone biology and bone diseases. The functions and exact mechanism of bone-related lncRNAs have not been fully classified yet.

OBJECTIVE

The objective of this article is to summarize the current literature on lncRNAs on the basis of their role in bone biology and diseases, focusing on their emerging molecular mechanism, pathological implications and therapeutic potential.

DISCUSSION

A number of lncRNAs have been identified and shown to play important roles in multiple bone cells and bone disease. The function and mechanism of bone-related lncRNA remain to be elucidated.

CONCLUSION

At present, majority of knowledge is limited to cellular levels and less is known on how lncRNAs could potentially control the development and homeostasis of bone. In the present review, we highlight some lncRNAs in the field of bone biology and bone disease. We also delineate some lncRNAs that might have deep impacts on understanding bone diseases and providing new therapeutic strategies to treat these diseases.

LncRNA DANCR and miR-320a suppressed osteogenic differentiation in osteoporosis by directly inhibiting the Wnt/β-catenin signaling pathway

Our study aimed to determine how lncRNA DANCR, miR-320a, and CTNNB1 interact with each other and regulate osteogenic differentiation in osteoporosis. qRT-PCR and western blotting were performed to determine the expression of DANCR, miR-320a, CTNNB1, and the osteoporosis- or Wnt/β-catenin pathway-related markers T-cell factor 1 (TCF-1), runt-related transcription factor 2 (RUNX2), alkaline phosphatase (ALP), osteocalcin (OCN), and osteopontin (OPN). Interactions between CTNNB1, DANCR, and miR-320a were predicted by bioinformatics approaches and validated using a luciferase assay. Osteoblastic phenotypes were evaluated by ALP staining, ALP activity assay and Alizarin Red staining. The bilateral ovariectomy method was used to establish an in vivo osteoporosis model. Bone morphological changes were examined using hematoxylin and eosin (H&E) and Alcian Blue staining. The expression levels of DANCR and miR-320a in BMSCs derived from osteoporosis patients were upregulated, whereas CTNNB1 expression was downregulated compared with that in healthy controls. Importantly, we demonstrated that miR-320a and DANCR acted independently from each other and both inhibited CTNNB1 expression, whereas the inhibitory effect was additive when miR-320a and DANCR were cooverexpressed. Moreover, we found that DANCR overexpression largely abrogated the effect of the miR-320a inhibitor on CTNNB1 expression and the Wnt/β-catenin signaling pathway in BMSCs during osteogenic differentiation. We further confirmed the results above in BMSCs derived from an osteoporosis animal model. Taken together, our findings revealed that DANCR and miR-320a regulated the Wnt/β-catenin signaling pathway during osteogenic differentiation in osteoporosis through CTNNB1 inhibition. Our results highlight the potential value of DANCR and miR-320a as promising therapeutic targets for osteoporosis treatment.

Two non-coding RNAs are potential targets for reducing bone loss in post-menopausal osteoporosis. Bones are constantly being remodeled; when resorption outpaces generation of new bone, bones are weakened, causing osteoporosis and leading to decreased quality of life and injuries. Although treatments exist, they often have undesirable side effects, and new treatments are needed. The molecular basis of the changes that accompany osteoporosis are poorly understood. Da Zhong at the Xiangya Hospital of Central South University in Changsha, China, and co-workers investigated how two non-coding RNAs, small molecules that regulate gene expression, are involved in the progression of post-menopausal osteoporosis. They found that levels of both molecules are increased in osteoporosis, and that silencing them increases building of new bone, key to maintaining bone strength. These results illuminate a potential new direction in treatments for osteoporosis.

lncRNA GAS5 Is Upregulated in Osteoporosis and Downregulates miR-21 to Promote Apoptosis of Osteoclasts

Background

It has been reported that lncRNA growth arrest-specific transcript 5 (GAS5) interacts with miR-21, which plays critical roles in osteoporosis. The involvement of GAS5 in osteoporosis was investigated in this study.

Methods

Expression levels of GAS5 and miR-21 in plasma of both osteoporosis patients and healthy controls were determined by RT-qPCR. Diagnostic values of GAS5 and miR-21 for osteoporosis were analyzed by ROC curve analysis. Overexpression experiments were used to assess the interactions between GAS5 and miR-21. The roles of GAS5 and miR-21 in the apoptosis of osteoclasts were investigated by cell apoptosis assay.

Results

The present study aimed to investigate the roles of GAS5 in osteoporosis. The results showed that GAS5 was upregulated, while miR-21 was downregulated in plasma of osteoporosis patients. Expression levels of GAS5 and miR-21 were inversely correlated across plasma samples from osteoporosis patients but not the plasma samples from the controls. Altered expression of GAS5 and miR-21 distinguished osteoporosis patients from the controls. In osteoclasts, overexpression of GAS5 led to downregulation of miR-21, while overexpression of miR-21 did not affect the expression of GAS5. Overexpression of GAS5 led to promoted apoptosis of osteoclasts, while overexpression of miR-21 led to suppressed apoptosis of osteoclasts. In addition, overexpression of miR-21 attenuated the enhancing effects of overexpressing GAS5 on cell apoptosis.

Conclusion

GAS5 is upregulated in osteoporosis and may downregulate miR-21 to promote the apoptosis of osteoclasts.

Down-regulation of FTX promotes the differentiation of osteoclasts in osteoporosis through the Notch1 signaling pathway by targeting miR-137

BACKGROUND

Osteoporosis (OP) is one of the commonly seen bone diseases with low bone mineral densities and trauma fractures. Accumulative studies have demonstrated that the occurrence of OP is closely related to osteoclasts differentiation. LncRNA FTX has been demonstrated to inhibit the development of some human cancers. However, its potential functions in human OP remains to be elusive.

METHODS

The expressions of FTX and miR-137 in bone and serum samples of patients with or without OP were measured. Bioinformatics analysis, RIP assays and luciferase reporter assays were performed to examine the upstream and downstream transactional factors of miR-137. Functional assays were conducted to check the roles of the Notching1 signaling pathway OP.

RESULTS

FTX was suppressed in OP samples and serums, however, miR-137 was greatly elevated. FTX reduced osteoclast-genesis and inhibited osteogenic differentiation by targeting miR-137. This also inhibited the Notch1 signaling pathway.

CONCLUSION

Our experiments and results pointed out that lncRNA FTX up-regulated miR-137 in OP through the Notch1 signaling pathway.

The Role of Micro RNA and Long-Non-Coding RNA in Osteoporosis

Osteoporosis is a major concern worldwide and can be attributed to an imbalance between osteoblastic bone formation and osteoclastic bone resorption due to the natural aging process. Heritable factors account for 60-80% of optimal bone mineralization; however, the finer details of pathogenesis remain to be elucidated. Micro RNA (miRNA) and long-non-coding RNA (lncRNA) are two targets that have recently come into the spotlight due to their ability to control gene expression at the post-transcriptional level and provide epigenetic modification. miRNAs are a class of non-coding RNAs that are approximately 18-25 nucleotides long. It is thought that up to 60% of human protein-coding genes may be regulated by miRNAs. They have been found to regulate gene expression that controls osteoblast-dependent bone formation and osteoclast-related bone remodeling. lncRNAs are highly structured RNA transcripts longer than 200 nucleotides that do not translate into proteins. They have very complex secondary and tertiary structures and the same degradation processes as messenger RNAs. The fact that they have a rapid turnover is due to their sponge function in binding the miRNAs that lead to a degradation of the lncRNA itself. They can act as signaling, decoy, and framework molecules, or as primers. Current evidence suggests that lncRNAs can act as chromatin and transcriptional as well as post-transcriptional regulators. With regards to osteoporosis, lncRNA is thought to be involved in the proliferation, apoptosis, and inflammatory response of the bone. This review, which is based on a systematic appraisal of the current literature, provides current molecular and genetic opinions on the roles of miRNAs and lncRNAs in osteoporosis. Further research into the epigenetic modification and the regulatory roles of these molecules will bring us closer to potential disease-modifying treatment for osteoporosis. However, more issues regarding the detailed actions of miRNAs and lncRNAs in osteoporosis remain unknown and controversial and warrant future investigation.

Comparative profiles of DNA methylation and differential gene expression in osteocytic areas from aged and young mice

Altered DNA methylation upon ageing may result in many age-related diseases such as osteoporosis. However, the changes in DNA methylation that occur in cortical bones, the major osteocytic areas, remain unknown. In our study, we extracted total DNA and RNA from the cortical bones of 6-month-old and 24-month-old mice and systematically analysed the differentially methylated regions (DMRs), differentially methylated promoters (DMPs) and differentially expressed genes (DEGs) between the mouse groups. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis of the DMR-related genes revealed that they were mainly associated with metabolic signalling pathways, including glycolysis, fatty acid and amino acid metabolism. Other genes with DMRs were related to signalling pathways that regulate the growth and development of cells, including the PI3K-AKT, Ras and Rap1 signalling pathways. The gene expression profiles indicated that the DEGs were mainly involved in metabolic pathways and the PI3K-AKT signalling pathway, and the profiles were verified through real-time quantitative PCR (RT-qPCR). Due to the pivotal roles of the affected genes in maintaining bone homeostasis, we suspect that these changes may be key factors in age-related bone loss, either together or individually. Our study may provide a novel perspective for understanding the osteocyte and its relationship with osteoporosis during ageing. SIGNIFICANCE OF THE STUDY: Our study identified age-related changes in gene expressions in osteocytic areas through whole-genome bisulfite sequencing (WGBS) and RNA-seq, providing new theoretical foundations for the targeted treatment of senile osteoporosis.

LncRNA TUG1 was upregulated in osteoporosis and regulates the proliferation and apoptosis of osteoclasts

Background

Long non-coding RNA (LncRNA) TUG1 plays critical roles in the development of human cancers. Its inhibition has been proved to participate in ankylosing spondylitis, which is an inverse pathological procedure of osteoporosis. In the present study, we aim to investigate the role of lncRNA TUG1 in ankylosing spondylitis.

Materials and methods

Expressions of lncRNA TUG1 in plasma of 98 patients with osteoporosis and 60 healthy participants were detected by real-time quantitative PCR (RT-qPCR). Diagnostic values of lncRNA CASC11 for osteoclasts were performed by the ROC curve with osteoporosis patients as positive and healthy participants as negative. All experiments were repeated 3 times. Mean ± standard deviation was calculated.

Results

We found that plasma lncRNA TUG1 was upregulated in osteoporosis patients than in healthy participants. Upregulation of plasma lncRNA TUG1 distinguished osteoporosis patients from healthy participants. LncRNA TUG1 level increased with the advances of clinical stages. Over-expression of lncRNA TUG1 promoted the proliferation and inhibited the apoptosis of mice osteoclasts, while lncRNA TUG1 siRNA silencing played an opposite role. In addition, lncRNA TUG1 over-expression led to downregulated PTEN, while lncRNA TUG1 siRNA silencing played an opposite role.

Conclusion

Therefore, lncRNA TUG1 is upregulated in osteoporosis and regulates the proliferation and apoptosis of osteoclasts. lncRNA TUG1 knockdown may serve as a promising therapeutic target for osteoporosis by inhibiting the proliferation and promoting the apoptosis of osteoclasts through PTEN.

MicroRNA-410 participates in the pathological process of postmenopausal osteoporosis by downregulating bone morphogenetic protein-2

The present study aimed to investigate bone morphogenetic protein (BMP)-2 and microRNA (miR)-410 expression and the mechanism of regulation in serum and CD¹⁴⁺ peripheral blood mononuclear cells (PBMCs) from postmenopausal osteoporosis patients and model mice. A total of 26 patients with postmenopausal osteoporosis were included in the experimental group and 29 age-matched healthy subjects were included in the control group. A total of 60 mice were divided into sham and ovariectomized (OVX) groups. Following surgery, 28 mice remained in the sham and 25 mice remained in OVX group. BMP-2 protein expression in serum and CD¹⁴⁺ PBMCs from patients and model mice was determined using ELISA and western blotting, respectively. Reverse transcription-quantitative polymerase chain reaction assays were performed to determine miR-410 and BMP-2 mRNA levels in serum and CD¹⁴⁺ PBMCs from patients and model mice. Dual luciferase reporter assays were used to identify direct interactions between miR-410 and BMP-2 mRNA. Compared with the control group, BMP-2 mRNA and protein expression in serum and CD¹⁴⁺ PBMCs from patients with postmenopausal osteoporosis and model mice were significantly decreased. miR-410 levels in serum and CD¹⁴⁺ PBMCs from patients with postmenopausal osteoporosis and model mice were significantly increased when compared with the control group. Dual luciferase reporter assays revealed that BMP-2 was a target gene of miR-410. The current study demonstrated that decreased BMP-2 expression in serum and CD¹⁴⁺ PBMCs from patients with postmenopausal osteoporosis was associated with the upregulation of miR-410. These results suggest that miR-410 may participate in the pathological process of postmenopausal osteoporosis by downregulating BMP-2.

Predicting miRNA-lncRNA interactions and recognizing their regulatory roles in stress response of plants

It has been found that each non-coding RNA (ncRNA) can act not only through its target gene, but also interact with each other to act on biological traits, and this interaction is more common. Many studies focus mainly on the analysis of microRNA(miRNA) and message RNA (mRNA) interactions. In this study, we investigated miRNA and long non-coding RNA (lncRNA) interactions using support vector regression (SVR) for prediction of new target genes in Arabidopsis thaliana and identify some regulatory roles in stress response. The networks of miRNA-mRNA, miRNA-lncRNA and miRNA-mRNA-lncRNA were constructed. They were further analyzed and interpreted in R. We showed that miRNA with low sequence number, targeted lncRNA with high sequence number and miRNA with high sequence number targeted lncRNA with low sequence number. The experimental results showed that there is a regulatory relationship between miRNA-lncRNA. New RNA targets were predicted using SVR with new gene expression mechanism and the stress related functions were annotated.

Long noncoding RNAs: a missing link in osteoporosis

Osteoporosis is a systemic disease that results in loss of bone density and increased fracture risk, particularly in the vertebrae and the hip. This condition and associated morbidity and mortality increase with population ageing. Long noncoding (lnc) RNAs are transcripts longer than 200 nucleotides that are not translated into proteins, but play important regulatory roles in transcriptional and post-transcriptional regulation. Their contribution to disease onset and development is increasingly recognized. Herein, we present an integrative revision on the studies that implicate lncRNAs in osteoporosis and that support their potential use as therapeutic tools. Firstly, current evidence on lncRNAs involvement in cellular and molecular mechanisms linked to osteoporosis and its major complication, fragility fractures, is reviewed. We analyze evidence of their roles in osteogenesis, osteoclastogenesis, and bone fracture healing events from human and animal model studies. Secondly, the potential of lncRNAs alterations at genetic and transcriptomic level are discussed as osteoporosis risk factors and as new circulating biomarkers for diagnosis. Finally, we conclude debating the possibilities, persisting difficulties, and future prospects of using lncRNAs in the treatment of osteoporosis.

Parathyroid hormone-stimulation of Runx2 during osteoblast differentiation via the regulation of lnc-SUPT3H-1:16 (RUNX2-AS1:32) and miR-6797-5p

Parathyroid hormone (PTH) acts as a regulator of calcium homeostasis and bone remodeling. Runx2, an essential transcription factor in bone, is required for osteoblast differentiation. Noncoding RNAs such as long noncoding RNAs (lncRNAs) and microRNAs (miRNAs) play crucial roles in regulating gene expression in osteoblasts. In this study, we investigated the effects of PTH on osteoblast differentiation via Runx2, lncRNA, and miRNA expression in human bone marrow stromal cells (hBMSCs) and human osteoblastic cells (MG63). PTH-treatment of hBMSCs for 24 h, 7 days, and 14 days stimulated Runx2 mRNA expression. Using bioinformatics tools, we identified 17 lncRNAs originating from human Runx2 gene. Among these, lnc-SUPT3H-1:16 (RUNX2-AS1:32) expression was highly up-regulated by the 7 d PTH-treatment in hBMSCs. We also identified miR-6797-5p as the putative target of lnc-SUPT3H-1:16 and Runx2 using bioinformatics tools. PTH-treatment increased the expression of miR-6797-5p in hBMSCs, and overexpression of miR-6797-5p decreased osteoblast differentiation in MG63 cells, suggesting a role for lnc-SUPT3H-1:16 as sponge molecule. A luciferase gene reporter assay identified direct targeting of miR-6797-5p with lnc-SUPT3H-1:16 and 3'UTR Runx2 in MG63 cells. Thus, PTH stimulated the expression of lnc-SUPT3H-1:16, miR-6797-5p and Runx2, and due to the sponging mechanism of lnc- SUPT3H-1:16 towards miR-6797-5p, Runx2 was protected, resulting in the promotion of osteoblast differentiation.

The diagnostic value and pathogenetic role of lncRNA-ATB in patients with osteoarthritis

Background

In view of the roles of long non-coding RNAs (lncRNAs) in human diseases and the high incidence of osteoarthritis, we investigated the role of long non-coding RNA activated by transforming growth factor-β (lncRNA-ATB) in osteoarthritis and explored its diagnostic value for this disease.

Methods

The study involved 98 patients with osteoarthritis and 76 healthy subjects. Blood was extracted from each participant and the expression of lncRNA-ATB in the serum was detected using quantitative Real Time -PCR. ROC curve analysis was performed to evaluate the diagnostic value of lncRNA-ATB for osteoarthritis. Based on the median serum level of lncRNA-ATB, patients were divided into a high-level group and a low-level group. Correlations between the serum levels of lncRNA-ATB and basic information about the patients were analyzed using the chi-square test. LncRNA-ATB overexpression in human chondrocyte cell line CHON-001 (ATCC CRL-2846) was established to study the effects on chondrocyte proliferation (using the CCK-8 assay) and viability.

Results

LncRNA-ATB expression was significantly downregulated in the serum of osteoarthritis patients compared with the healthy controls, meaning this downregulation effectively distinguished osteoarthritis patients from healthy subjects. LncRNA-ATB expression in the serum was not significantly affected by the patients’ gender, age or habits, including smoking and alcohol consumption. LncRNA-ATB overexpression activated Akt signaling, promoted proliferation and increased the viability of the chondrocytes.

Conclusion

We conclude that downregulation of lncRNA-ATB in serum is a reliable diagnostic marker for osteoarthritis and that this lncRNA participates in the pathogenesis of osteoarthritis by regulating the proliferation and viability of chondrocytes through the activation of Akt signaling.

Electronic supplementary material

The online version of this article (10.1186/s11658-018-0118-9) contains supplementary material, which is available to authorized users.

Diosgenin protects against alveolar bone loss in ovariectomized rats via regulating long non-coding RNAs

The present study assessed the changes in long non-coding (lnc)RNA and mRNA expression profiles when diosgenin (DIO) exerted a potential osteoprotective effect on the alveolar bone of ovariectomized (OVX) rats. Female Wistar rats underwent a sham operation (SHAM group) or ovariectomy. OVX rats were treated using vehicle (OVX group), DIO (DIO group) or estradiol valerate (EV group) for 12 weeks. After treatment, the biomarkers of bone turnover in plasma and the microstructure of alveolar bone were assessed. lncRNA microarrays were applied to assess lncRNA and mRNA expression profiles in alveolar bone in the OVX and DIO group rats. Subsequently, the differentially expressed mRNAs associated with the comprehensive bone metabolism pathway in Ingenuity Pathway Analysis (IPA) were identified and regarded as key mRNAs. Based on some of the key mRNAs and all the differentially expressed lncRNAs, a coexpression network was established and this network was further analyzed to identify the top 6 lncRNAs with the highest closeness scores (pivotal lncRNAs). Finally, 6 modules showing interactions between pivotal lncRNAs and key mRNAs were constructed. All of the pivotal lncRNAs and key mRNAs were validated with reverse transcription-quantitative polymerase chain reaction. The present findings demonstrated that DIO suppressed the loss of alveolar bone in OVX rats, and the changes to the expression of some lncRNAs or mRNAs occurred in the alveolar bone of the rats in the DIO group. Twenty-four key mRNAs were identified during pathway analysis. Furthermore, 8/24 key mRNAs (Ctnnb1, Smad4, Tcf2, Sp7, Il1b, Il1r1, Tnf and Tnfrsf1a) were used to establish a coexpression network, which included 1,656 nodes and 5,341 edges. During network analysis, 6 pivotal lncRNAs (XR_008346, MRuc007iji, MRAK157089, MRAK076413, MRAK143591 and AB036696) were obtained, and 6 modules illustrating pivotal lncRNA-key mRNA interactions were identified. These results revealed that the anti-osteoporotic effect of DIO on alveolar bone may be associated with the promotion of a bone formation process through increasing the signaling of the Wnt and BMPs pathways and the inhibition of the bone resorption process through decreasing stimulators of osteoclastogenesis. To conclude, several pivotal lncRNAs may serve important roles in these processes via regulating some key mRNAs in the bone metabolism pathway.

Role of lncRNAs in aging and age-related diseases

Aging is progressive physiological degeneration and consequently declined function, which is linked to senescence on both cellular and organ levels. Accumulating studies indicate that long noncoding RNAs (lncRNAs) play important roles in cellular senescence at all levels-transcriptional, post-transcriptional, translational, and post-translational. Understanding the molecular mechanism of lncRNAs underlying senescence could facilitate interpretation and intervention of aging and age-related diseases. In this review, we describe categories of known and novel lncRNAs that have been involved in the progression of senescence. We also identify the lncRNAs implicated in diseases arising from age-driven degeneration or dysfunction in some representative organs and systems (brains, liver, muscle, cardiovascular system, bone pancreatic islets, and immune system). Improved comprehension of lncRNAs in the aging process on all levels, from cell to organismal, may provide new insights into the amelioration of age-related pathologies and prolonged healthspan.

Exploring the Role of Fallopian Ciliated Cells in the Pathogenesis of High-Grade Serous Ovarian Cancer

High-grade serous epithelial ovarian cancer (HGSOC) is the fifth leading cause of cancer death in women and the first among gynecological malignancies. Despite an initial response to standard chemotherapy, most HGSOC patients relapse. To improve treatment options, we must continue investigating tumor biology. Tumor characteristics (e.g., risk factors and epidemiology) are valuable clues to accomplish this task. The two most frequent risk factors for HGSOC are the lifetime number of ovulations, which is associated with increased oxidative stress in the pelvic area caused by ovulation fluid, and a positive family history due to genetic factors. In the attempt to identify novel genetic factors (i.e., genes) associated with HGSOC, we observed that several genes in linkage with HGSOC are expressed in the ciliated cells of the fallopian tube. This finding made us hypothesize that ciliated cells, despite not being the cell of origin for HGSOC, may take part in HGSOC tumor initiation. Specifically, malfunction of the ciliary beat impairs the laminar fluid flow above the fallopian tube epithelia, thus likely reducing the clearance of oxidative stress caused by follicular fluid. Herein, we review the up-to-date findings dealing with HGSOC predisposition with the hypothesis that fallopian ciliated cells take part in HGSOC onset. Finally, we review the up-to-date literature concerning genes that are located in genomic loci associated with epithelial ovarian cancer (EOC) predisposition that are expressed by the fallopian ciliated cells.

Bone remodeling induced by mechanical forces is regulated by miRNAs

The relationship between mechanical force and alveolar bone remodeling is an important issue in orthodontics because tooth movement is dependent on the response of bone tissue to the mechanical force induced by the appliances used. Mechanical cyclical stretch (MCS), fluid shear stress (FSS), compression, and microgravity play different roles in the cell differentiation and proliferation involved in bone remodeling. However, the underlying mechanisms are unclear, particularly the molecular pathways regulated by non-coding RNAs (ncRNAs) that play essential roles in bone remodeling. Amongst the various ncRNAs, miRNAs act as post-transcriptional regulators that inhibit the expression of their target genes. miRNAs are considered key regulators of many biologic processes including bone remodeling. Here, we review the role of miRNAs in mechanical force-induced bone metabolism.

Epigenetics of Skeletal Diseases

PURPOSE OF REVIEW

Epigenetic mechanisms modify gene activity in a stable manner without altering DNA sequence. They participate in the adaptation to the environment, as well as in the pathogenesis of common complex disorders. We provide an overview of the role of epigenetic mechanisms in bone biology and pathology.

RECENT FINDINGS

Extensive evidence supports the involvement of epigenetic mechanisms (DNA methylation, post-translational modifications of histone tails, and non-coding RNAs) in the differentiation of bone cells and mechanotransduction. A variety of epigenetic abnormalities have been described in patients with osteoporosis, osteoarthritis, and skeletal cancers, but their actual pathogenetic roles are still unclear. A few drugs targeting epigenetic marks have been approved for neoplastic disorders, and many more are being actively investigated. Advances in the field of epigenetics underscore the complex interactions between genetic and environmental factors as determinants of osteoporosis and other common disorders. Likewise, they help to explain the mechanisms by which prenatal and post-natal external factors, from nutrition to psychological stress, impact our body and influence the risk of later disease.

Role of nutritional vitamin D in osteoporosis treatment

Osteoporosis is a systemic skeletal disorder characterized by a decrease in bone mass and microarchitectural deterioration of bone tissue. The World Health Organization has defined osteoporosis as a decrease in bone mass (50%) and bony quality (50%). Vitamin D, a steroid hormone, is crucial for skeletal health and in mineral metabolism. Its direct action on osteoblasts and osteoclasts and interaction with nonskeletal tissues help in maintaining a balance between bone turnover and bone growth. Vitamin D affects the activity of osteoblasts, osteoclasts, and osteocytes, suggesting that it affects bone formation, bone resorption, and bone quality. At physiological concentrations, active vitamin D maintains a normal rate of bone resorption and formation through the RANKL/OPG signal. However, active vitamin D at pharmacological concentration inhibits bone resorption at a higher rate than that of bone formation, which influences the bone quality and quantity. Nutritional vitamin D rather than active vitamin D activates osteoblasts and maintains serum 25(OH)D₃ concentration. Despite many unanswered questions, much data support nutritional vitamin D use in osteoporosis patients. This article emphasizes the role of nutritional vitamin D replacement in different turnover status (high or low bone turnover disorders) of osteoporosis together with either anti-resorptive (Bisphosphonate, Denosumab et.) or anabolic (Teriparatide) agents when osteoporosis persists.

Systematic analysis of lncRNAs, mRNAs, circRNAs and miRNAs in patients with postmenopausal osteoporosis

Osteoporosis (OP) is a disease characterized by bone loss, imbalance of bone metabolism and destruction of trabecular microstructure, and associated with menopause. Studies have shown that immune related lymphocytes are involved in bone metabolism. However, the molecular mechanisms hidden in the interaction of lymphocytes with OP need to be further studied. In the present study, we investigated the expression profiles and differences of lncRNAs, mRNAs, circRNAs and miRNAs in peripheral blood lymphocytes of patients with postmenopausal OP using Illumina-based complementary DNA (cDNA) deep sequencing (RNA-seq). 70 lncRNAs, 475 mRNAs, 260 circRNAs and 13 miRNAs were differentially expressed in patients with postmenopausal osteoporosis (OP group) compared with healthy controls (NC group). The functions of differentially expressed lncRNAs, circRNA, miRNA and potential targeting genes were predicted by Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis. Complex lncRNA-miRNA-mRNA and circRNA-miRNA-mRNA regulatory networks were constructed based on differentially expressed RNAs. Taken together, our study indicated that lncRNAs, mRNA, circRNAs and miRNA could associate with the occurrence of postmenopausal OP and may be as possible biomarkers and target genes in lymphocytes for OP.

MicroRNA‑148a inhibition protects against ovariectomy‑induced osteoporosis through PI3K/AKT signaling by estrogen receptor α

The present study aimed to investigate the effect of microRNA‑148a downregulation on osteoporosis by using an ovariectomized rat model. Reverse transcription‑quantitative polymerase chain reaction was used to analyze microRNA‑148a expression levels, MTT and flow cytometry assays were used to examine cytotoxicity and apoptosis, respectively. The gap‑associated proteins were quantified using western blotting. The expression of microRNA‑148a was significantly increased in osteoporosis rat following ovariectomy. Overexpression of microRNA‑148a significantly promoted apoptosis and inhibited cell growth, whereas downregulation of microRNA‑148a significantly reduced apoptosis and increased cell growth. Overexpression of microRNA‑148a significantly reduced estrogen receptor a (ERα) protein expression and suppressed phosphoinositide‑3‑kinase regulatory subunit 1 (PI3K) and phosphorylated‑protein kinase B (AKT) protein expression in osteoblasts in vitro. The inhibition of ERα increased the microRNA‑148a effect on apoptosis in osteoblasts in vitro. Subsequently, LY294002, an PI3K inhibitor, significantly increased the effect of microRNA‑148a on apoptosis in osteoblasts in vitro. The findings of the present study revealed that anti‑microRNA‑148a protected cells against ovariectomy‑induced osteoporosis through ERα by PI3K/AKT signaling.

Long Non-coding RNAs: A New Regulatory Code for Osteoporosis

Osteoporosis is a metabolic bone disease characterized by a decrease in bone mass and degradation of the bone microstructure, which increases bone fragility and fracture risk. However, the molecular mechanisms of osteoporosis remain unclear. Long non-coding RNAs (lncRNAs) have become important epigenetic regulators controlling the expression of genes and affecting multiple biological processes. Accumulating evidence of the involvement of lncRNAs in bone remolding has increased understanding of the molecular mechanisms underlying osteoporosis. This review aims to summarize recent progress in the elucidation of the role of lncRNAs in bone remodeling, and how it contributes to osteoblast and osteoclast function. This knowledge will facilitate the understanding of lncRNA roles in bone biology and shed new light on the modulation and potential treatment of osteoporosis.