FOXOs attenuate bone formation by suppressing Wnt signaling

Role of O-linked N-acetylglucosamine protein modification in oxidative stress-induced autophagy: a novel target for bone remodeling

O-linked N-acetylglucosamine protein modification (O-GlcNAcylation) is a dynamic post-translational modification (PTM) involving the covalent binding of serine and/or threonine residues, which regulates bone cell homeostasis. Reactive oxygen species (ROS) are increased due to oxidative stress in various pathological contexts related to bone remodeling, such as osteoporosis, arthritis, and bone fracture. Autophagy serves as a scavenger for ROS within bone marrow-derived mesenchymal stem cells, osteoclasts, and osteoblasts. However, oxidative stress-induced autophagy is affected by the metabolic status, leading to unfavorable clinical outcomes. O-GlcNAcylation can regulate the autophagy process both directly and indirectly through oxidative stress-related signaling pathways, ultimately improving bone remodeling. The present interventions for the bone remodeling process often focus on promoting osteogenesis or inhibiting osteoclast absorption, ignoring the effect of PTM on the overall process of bone remodeling. This review explores how O-GlcNAcylation synergizes with autophagy to exert multiple regulatory effects on bone remodeling under oxidative stress stimulation, indicating the application of O-GlcNAcylation as a new molecular target in the field of bone remodeling.

Wnt/β-catenin signaling pathway as an important mediator in muscle and bone crosstalk: A systematic review

Background

The interaction between muscle and bone is shown to be clinically important but the underlying mechanisms are largely unknown. The canonical Wnt/β-catenin signaling pathway is reported to be involved in muscle-bone crosstalk, but its detailed function remains unclear. This systematic review aims to investigate and elucidate the role of the Wnt/β-catenin signaling pathways in muscle-bone crosstalk.

Methods

We conducted a literature search on the Web of Science, PubMed, EBSCO and Embase with keywords "Wnt*", "bone*" and "muscle*". A systematic review was completed according to the guideline of preferred reporting items of systematic reviews and meta-analyses (PRISMA). Data synthesis included species (human, animal or cell type used), treatments involved, outcome measures and key findings with respect to Wnts.

Results

Seventeen papers were published from 2007 to 2021 and were extracted from a total of 1529 search results in the databases of Web of Science (468 papers), PubMed (457 papers), EBSCO (371) and Embase (233). 12 Wnt family members were investigated in the papers, including Wnt1, Wnt2, Wnt2b, Wnt3a, Wnt4, Wnt5a, Wnt8a, Wnt8b, Wnt9a, Wnt10a, Wnt10b and Wnt16. Many studies showed that muscles were able to increase or decrease osteogenesis of bone, while bone increased myogenesis of muscle through Wnt/β-catenin signaling pathways. Wnt3a, Wnt4 and Wnt10b were shown to play important roles in the crosstalk between muscle and bone.

Conclusions

Wnt3a, Wnt4 and Wnt10b are found to play important mediatory roles in muscle-bone crosstalk. The role of Wnt4 was mostly found to regulate muscle from the bone side. Whilst the role of Wnt10b during muscle ageing was proposed, current evidence is insufficient to clarify the specific role of Wnt/β-catenin signaling in the interplay between sarcopenia and osteoporosis. More future studies are required to investigate the exact regulatory roles of Wnts in muscle-bone crosstalk in musculoskeletal disease models such as sarcopenia and osteoporosis.

Translational potential of this article

The systematic review provides an extensive overview to reveal the roles of Wnt/β-catenin signaling pathways in muscle-bone crosstalk. These results provide novel research directions to further understand the underlying mechanism of sarcopenia, osteoporosis, and their crosstalk, finally helping the future development of new therapeutic interventions.

Musculoskeletal crosstalk in chronic obstructive pulmonary disease and comorbidities: Emerging roles and therapeutic potentials

Chronic Obstructive Pulmonary Disease (COPD) is a multifaceted respiratory disorder characterized by progressive airflow limitation and systemic implications. It has become increasingly apparent that COPD exerts its influence far beyond the respiratory system, extending its impact to various organ systems. Among these, the musculoskeletal system emerges as a central player in both the pathogenesis and management of COPD and its associated comorbidities. Muscle dysfunction and osteoporosis are prevalent musculoskeletal disorders in COPD patients, leading to a substantial decline in exercise capacity and overall health. These manifestations are influenced by systemic inflammation, oxidative stress, and hormonal imbalances, all hallmarks of COPD. Recent research has uncovered an intricate interplay between COPD and musculoskeletal comorbidities, suggesting that muscle and bone tissues may cross-communicate through the release of signalling molecules, known as "myokines" and "osteokines". We explored this dynamic relationship, with a particular focus on the role of the immune system in mediating the cross-communication between muscle and bone in COPD. Moreover, we delved into existing and emerging therapeutic strategies for managing musculoskeletal disorders in COPD. It underscores the development of personalized treatment approaches that target both the respiratory and musculoskeletal aspects of COPD, offering the promise of improved well-being and quality of life for individuals grappling with this complex condition. This comprehensive review underscores the significance of recognizing the profound impact of COPD on the musculoskeletal system and its comorbidities. By unravelling the intricate connections between these systems and exploring innovative treatment avenues, we can aspire to enhance the overall care and outcomes for COPD patients, ultimately offering hope for improved health and well-being.

Comprehensive analysis of circRNA expression profiles in postmenopausal women differing in bone mineral density

Postmenopausal osteoporosis (PMOP) seriously endangers the bone health of older women. Although there are currently indicators to diagnose PMOP, early diagnostic biomarkers are lacking. Circular ribonucleic acid (circRNA) has a stable structure, regulates gene expression, participates in the pathological process of disease, and has the potential to become a biomarker. The purpose of this study was to investigate circRNAs that could be used to predict patients with early PMOP. Ribonucleic acid (RNA) sequencing was performed on peripheral blood leukocytes from 15 female patients to identify differential circRNAs between different groups. Using bioinformatics analysis, enrichment analysis was performed to discover relevant functions and pathways. CircRNA-micro ribonucleic acid (miRNA) interaction analysis and messenger ribonucleic acid (mRNA) prediction and network construction help us to understand the relationship between circRNA, miRNA, and mRNA. Quantitative real-time polymerase chain reaction (qRT-PCR) was used to validate the gene expression of candidate circRNAs. We screened out 2 co-expressed differential circRNAs, namely hsa_circ_0060849 and hsa_circ_0001394. By analyzing the regulatory network, a total of 54 miRNAs and 57 osteoporosis-related mRNAs were identified, which, as potential downstream target genes of hsa_circ_0060849 and hsa_circ_0001394, may play a key role in the occurrence and development of PMOP. The occurrence and development of PMOP is regulated by circRNAs, and hsa_circ_0060849 and hsa_circ_0001394 can be used as new diagnostic markers and therapeutic targets for early PMOP.

Forkhead box O proteins: steering the course of stem cell fate

Stem cells are pivotal players in the intricate dance of embryonic development, tissue maintenance, and regeneration. Their behavior is delicately balanced between maintaining their pluripotency and differentiating as needed. Disruptions in this balance can lead to a spectrum of diseases, underscoring the importance of unraveling the complex molecular mechanisms that govern stem cell fate. Forkhead box O (FOXO) proteins, a family of transcription factors, are at the heart of this intricate regulation, influencing a myriad of cellular processes such as survival, metabolism, and DNA repair. Their multifaceted role in steering the destiny of stem cells is evident, as they wield influence over self-renewal, quiescence, and lineage-specific differentiation in both embryonic and adult stem cells. This review delves into the structural and regulatory intricacies of FOXO transcription factors, shedding light on their pivotal roles in shaping the fate of stem cells. By providing insights into the specific functions of FOXO in determining stem cell fate, this review aims to pave the way for targeted interventions that could modulate stem cell behavior and potentially revolutionize the treatment and prevention of diseases.

FOXO is involved in antimicrobial peptides expression during WSSV infection in Exopalaemon carinicauda

The forkhead box transcription factor O family protein (FOXO) acts as a transcription factor that regulates biological processes regarding DNA repair, immunity, cell cycle regulation, and other biological processes. In this study, EcFOXO was identified from the ridgetail white prawn, Exopalaemon carinicauda. EcFOXO protein contains multiple low-complexity regions and a forkhead (FH) domain. Phylogenetic tree showed that EcFOXO is clustered with crustacean FOXOs. The amino acid sequences of its FH domain are highly similar to the FH domain of FOXOs from other crustaceans. The expression of EcFOXO is altered after white spot syndrome virus (WSSV) stimulation in hepatopancreas and gills. The relationship between EcFOXO and EcRelish was explored by RNA interference (RNAi). Results showed that EcFOXO and EcRelish could positively regulate each other's expression. The expression levels of various antimicrobial peptides (AMPs) significantly reduced after interfering with EcFOXO or EcRelish. These results suggest a positive regulatory loop between EcFOXO and EcRelish, which participates in the innate immunity of ridgetail white prawn by regulating the expression of AMPs during WSSV infection. This study enriches the knowledge about the regulatory mechanism of FOXO in the innate immunity of crustaceans.

Nanozymes With Osteochondral Regenerative Effects: An Overview of Mechanisms and Recent Applications

With the discovery of the intrinsic enzyme-like activity of metal oxides, nanozymes garner significant attention due to their superior characteristics, such as low cost, high stability, multi-enzyme activity, and facile preparation. Notably, in the field of biomedicine, nanozymes primarily focus on disease detection, antibacterial properties, antitumor effects, and treatment of inflammatory conditions. However, the potential for application in regenerative medicine, which primarily addresses wound healing, nerve defect repair, bone regeneration, and cardiovascular disease treatment, is garnering interest as well. This review introduces nanozymes as an innovative strategy within the realm of bone regenerative medicine. The primary focus of this approach lies in the facilitation of osteochondral regeneration through the modulation of the pathological microenvironment. The catalytic mechanisms of four types of representative nanozymes are first discussed. The pathological microenvironment inhibiting osteochondral regeneration, followed by summarizing the therapy mechanism of nanozymes to osteochondral regeneration barriers is introduced. Further, the therapeutic potential of nanozymes for bone diseases is included. To improve the therapeutic efficiency of nanozymes and facilitate their clinical translation, future potential applications in osteochondral diseases are also discussed and some significant challenges addressed.

Glutathione limits RUNX2 oxidation and degradation to regulate bone formation

Reactive oxygen species (ROS) are natural products of mitochondrial oxidative metabolism and oxidative protein folding. ROS levels must be well controlled, since elevated ROS has been shown to have deleterious effects on osteoblasts. Moreover, excessive ROS is thought to underlie many of the skeletal phenotypes associated with aging and sex steroid deficiency in mice and humans. The mechanisms by which osteoblasts regulate ROS and how ROS inhibits osteoblasts are not well understood. Here, we demonstrate that de novo glutathione (GSH) biosynthesis is essential in neutralizing ROS and establish a proosteogenic reduction and oxidation reaction (REDOX) environment. Using a multifaceted approach, we demonstrate that reducing GSH biosynthesis led to acute degradation of RUNX2, impaired osteoblast differentiation, and reduced bone formation. Conversely, reducing ROS using catalase enhanced RUNX2 stability and promoted osteoblast differentiation and bone formation when GSH biosynthesis was limited. Highlighting the therapeutic implications of these findings, in utero antioxidant therapy stabilized RUNX2 and improved bone development in the Runx2+/- haplo-insufficient mouse model of human cleidocranial dysplasia. Thus, our data establish RUNX2 as a molecular sensor of the osteoblast REDOX environment and mechanistically clarify how ROS negatively impacts osteoblast differentiation and bone formation.

Nicotinamide enhances osteoblast differentiation through activation of the mitochondrial antioxidant defense system

Although the normal physiological level of oxidative stress is beneficial for maintaining bone homeostasis, imbalance between reactive oxygen species (ROS) production and antioxidant defense can cause various bone diseases. The purpose of this study was to determine whether nicotinamide (NAM), an NAD⁺ precursor, can support the maintenance of bone homeostasis by regulating osteoblasts. Here, we found that NAM enhances osteoblast differentiation and mitochondrial metabolism. NAM increases the expression of antioxidant enzymes, which is due to increased FOXO3A transcriptional activity via SIRT3 activation. NAM has not only a preventive effect against weak and chronic oxidative stress but also a therapeutic effect against strong and acute exposure to H₂O₂ in osteoblast differentiation. Collectively, the results indicate that NAM increases mitochondrial biogenesis and antioxidant enzyme expression through activation of the SIRT3-FOXO3A axis, which consequently enhances osteoblast differentiation. These results suggest that NAM could be a potential preventive or therapeutic agent for bone diseases caused by ROS.

Tideglusib enhances odontogenic differentiation in human dental pulp stem cells in vitro

AIM

Tideglusib is a small molecule agonist of the canonical Wnt pathway. The present study investigated the influence of Tideglusib on human dental pulp stem cell (hDPSC) proliferation, apoptosis, migration and odonto/osteogenic differentiation.

METHODOLOGY

hDPSCs were treated with 50, 100 nM or 200 nM Tideglusib. β-catenin accumulation was detected by immunofluorescence staining. Colony-forming unit ability was assessed by staining with Coomassie blue. Cell cycle progression and cell apoptosis were investigated using flow cytometry. Cell migration was examined using an in vitro wound-healing assay. Osteogenic differentiation was examined using alkaline phosphatase (ALP) staining, alizarin red S staining and osteogenic-related gene expression. The gene expression profile was examined using a high-throughput RNA sequencing technique. All experiments were repeated using cells derived from at least four different donors (n = 4). The Mann-Whitney U-test was used to identify significant differences between two independent group comparisons. For three or more group comparisons, statistical differences were assessed using the Kruskal-Wallis test followed by pairwise comparison. The significance level was set at 5% (p < .05).

RESULTS

Tideglusib activated the Wnt signalling pathway in hDPSCs as demonstrated by an increase in cytoplasmic β-catenin accumulation and nuclear translocation. Tideglusib did not affect hDPSC proliferation, cell cycle progression, cell apoptosis or cell migration. In contrast, 50 and 100 nM Tideglusib significantly enhanced mineralization and osteogenic marker gene expression (RUNX2, ALP, BMP2 and DSPP; p < .05).

CONCLUSIONS

Tideglusib enhanced the odonto/osteogenic differentiation of hDPSCs. Therefore, incorporating this bioactive molecule in a pulp-capping material could be a promising strategy to promote dentine repair.

Effect of Biodentine on Odonto/Osteogenic Differentiation of Human Dental Pulp Stem Cells

This study aims to compare the biological characteristics of human dental pulp stem cells (hDPSCs) isolated from different-aged populations and examine the effects of Biodentine on proliferation and odonto/osteogenic differentiation of hDPSCs isolated from the elderly in vitro. hDPSCs were isolated from three different-aged populations: group A (≤18 years old), group B (19−59 years old), and group C (≥60 years old). The adhesion, proliferation, odonto/osteogenesis, and senescence were compared. The optimal concentration of aqueous Biodentine extract was determined by CCK-8 assay, alkaline phosphatase (ALP), and alizarin red staining (ARS). The effect of Biodentine on odonto/osteogenic gene and protein expression of hDPSCs in each group was evaluated by quantitative real-time PCR (QRT-PCR) and Western blot. hDPSCs were successfully isolated from three different-aged populations. Flow cytometry revealed that all isolated hDPSCs were positive for CD73 (>90%), CD90 (>90%), CD146 (<30%), and negative for CD45 (<1%). There existed an age-related decline in proliferation, odonto/osteogenic gene expression, and S-phase fraction (p < 0.05), an increase in senescence genes and p21 and p16 expression, and time needed for cell adhesion. Biodentine promoted hDPSC proliferation and mineralization in each group, particularly at a concentration of 0.2 mg/mL. Biodentine markedly enhanced odonto/osteogenesis-related gene and protein expression in each group (p < 0.05). hDPSCs can be obtained from populations of all ages. Though there is an age-related decline in their biological properties, hDPSCs from the elderly still maintain certain proliferation and multidirectional differentiation abilities. Biodentine can significantly promote the proliferation and odonto/osteogenic differentiation of hDPSCs isolated from the elderly over 60 years old, which could be considered a pulp capping material for vital pulp therapy in the elderly. Nevertheless, the efficacy of Biodentine in clinical application has to be further studied.

Glycemic Control and Bone in Diabetes

PURPOSE OF REVIEW

This review summarizes recent developments on the effects of glycemic control and diabetes on bone health. We discuss the foundational cellular mechanisms through which diabetes and impaired glucose control impact bone biology, and how these processes contribute to bone fragility in diabetes.

RECENT FINDINGS

Glucose is important for osteoblast differentiation and energy consumption of mature osteoblasts. The role of insulin is less clear, but insulin receptor deletion in mouse osteoblasts reduces bone formation. Epidemiologically, type 1 (T1D) and type 2 diabetes (T2D) associate with increased fracture risk, which is greater among people with T1D. Accumulation of cortical bone micro-pores, micro-vascular complications, and AGEs likely contribute to diabetes-related bone fragility. The effects of youth-onset T2D on peak bone mass attainment and subsequent skeletal fragility are of particular concern. Further research is needed to understand the effects of hyperglycemia on skeletal health through the lifecycle, including the related factors of inflammation and microvascular damage.

Small extracellular vesicles with nanomorphology memory promote osteogenesis

Nanotopographical cues endow biomaterials the ability to guide cell adhesion, proliferation, and differentiation. Cellular mechanical memory can maintain the cell status by retaining cellular information obtained from past mechanical microenvironments. Here, we propose a new concept “morphology memory of small extracellular vesicles (sEV)” for bone regeneration. We performed nanotopography on titanium plates through alkali and heat (Ti8) treatment to promote human mesenchymal stem cell (hMSC) differentiation. Next, we extracted the sEVs from the hMSC, which were cultured on the nanotopographical Ti plates for 21 days (Ti8-21-sEV). We demonstrated that Ti8-21-sEV had superior pro-osteogenesis ability in vitro and in vivo. RNA sequencing further confirmed that Ti8-21-sEV promote bone regeneration through osteogenic-related pathways, including the PI3K-AKT signaling pathway, MAPK signaling pathway, focal adhesion, and extracellular matrix-receptor interaction. Finally, we decorated the Ti8-21-sEV on a 3D printed porous polyetheretherketone scaffold. The femoral condyle defect model of rabbits was used to demonstrate that Ti8-21-sEV had the best bone ingrowth. In summary, our study demonstrated that the Ti8-21-sEV have memory function by copying the pro-osteogenesis information from the nanotopography. We expect that our study will encourage the discovery of other sEV with morphology memory for tissue regeneration.

•

Nanotopography fabricated on titanium plates has superior promoted hMSCs differentiation ability.

•

sEV extracted from hMSCs which were cultured on Ti8 plates for 21 days had the superior pro-osteogenesis ability.

•

Ti8-21-sEV have memory function through copy the pro-osteogenesis information from nanotopography.

•

RNA sequencing confirmed that Ti8-21-sEV promote bone regeneration through osteogenic-related pathways.

High glucose impairs osteogenic differentiation of embryonic stem cells via early diversion of beta-catenin from Forkhead box O to T cell factor interaction

BACKGROUND

Diabetes, which is characterized by an increase in blood glucose concentration, is accompanied by low bone turnover, increased fracture risk, and the formation of embryonic skeletal malformations. Yet, there are few studies elucidating the underlying alterations in signaling pathways leading to these osteogenic defects. We hypothesized here that bone formation deficiencies in a high glucose environment result from altered activity of beta-catenin (CTNNB1), a key contributor to osteogenic differentiation, dysregulation of which has also been implicated in the development of diabetes.

METHODS

To test this hypothesis, we used a previously established embryonic stem cell (ESC) model of differentiation that mimics the diabetic environment of the developing embryo. We differentiated murine ESCs within osteogenic-inducing media containing either high (diabetic) or low (physiological) levels of D-glucose and performed time course analyses to study the influence of high glucose on early and late bone cell differentiation.

RESULTS

Endpoint measures for osteogenic differentiation were reduced in a glucose-dependent manner and expression of precursor-specific markers altered at multiple time points. Furthermore, transcriptional activity of the lymphoid enhancer factor (LEF)/T cell factor (TCF) transcription factors during precursor formation stages was significantly elevated while levels of CTNNB1 complexed with Forkhead box O 3a (FOXO3a) declined. Modulation of AKT, a known upstream regulator of both LEF/TCF and FOXO3a, as well as CTNNB1 rescued some of the reductions in osteogenic output seen in the high glucose condition.

CONCLUSIONS

Within our in vitro model, we found a clear involvement of LEF/TCF and FOXO3a signaling pathways in the regulation of osteogenic differentiation, which may account for the skeletal deficiencies found in newborns of diabetic mothers.

Signaling pathways in obesity: mechanisms and therapeutic interventions

Obesity is a complex, chronic disease and global public health challenge. Characterized by excessive fat accumulation in the body, obesity sharply increases the risk of several diseases, such as type 2 diabetes, cardiovascular disease, and nonalcoholic fatty liver disease, and is linked to lower life expectancy. Although lifestyle intervention (diet and exercise) has remarkable effects on weight management, achieving long-term success at weight loss is extremely challenging, and the prevalence of obesity continues to rise worldwide. Over the past decades, the pathophysiology of obesity has been extensively investigated, and an increasing number of signal transduction pathways have been implicated in obesity, making it possible to fight obesity in a more effective and precise way. In this review, we summarize recent advances in the pathogenesis of obesity from both experimental and clinical studies, focusing on signaling pathways and their roles in the regulation of food intake, glucose homeostasis, adipogenesis, thermogenesis, and chronic inflammation. We also discuss the current anti-obesity drugs, as well as weight loss compounds in clinical trials, that target these signals. The evolving knowledge of signaling transduction may shed light on the future direction of obesity research, as we move into a new era of precision medicine.

FOXO1 differentially regulates bone formation in young and aged mice

It is a great challenge to develop a safe and effective treatment strategy for age-related osteoporosis and fracture healing. As one of the four FOXO transcription factors, FOXO1 is essential for cell proliferation, survival, senescence, energy metabolism, and oxidative stress in various cells. Our previous study demonstrated that specific Foxo1 gene deletion in osteoblasts in young mice results in bone loss while that in aged mice shows the opposite effect. However, the mechanism underlying the differential regulation of bone metabolism by FOXO1 remains to be elucidated. In this study, we generated osteoblast-specific Foxo1 knockout mice by using Foxo1^fl/fl and Bglap-Cre mice. In young mice, Foxo1 gene deletion inhibits osteoblast differentiation, leading to a decreased osteoblast number and decreased bone formation rate because of the weakened ability to resist oxidative stress, eventually resulting in bone loss and delayed healing of bone defects. In aged mice, high levels of reactive oxygen species (ROS) promote the diversion of CTNNB1 (β-catenin) from T cell factor 4 (TCF4)- to FOXO1-mediated transcription, thereby inhibiting Wnt/β-catenin signaling and leading to decreased osteogenic activity. Conversely, FOXO1 deficiency indirectly promotes the binding of β-catenin and TCF4 and activates Wnt/β-catenin signaling, thereby alleviating age-related bone loss and improving bone defect healing. Our study proves that FOXO1 has differential effects on bone metabolism in young and aged mice and elucidates its underlying mechanism. Further, this study provides a new perspective on the treatment of age-related osteoporosis.

Biochemical interaction of pyrvinium in gentamicin-induced acute kidney injury by modulating calcium dyshomeostasis and mitochondrial dysfunction

Acute kidney injury (AKI) has a poor clinical prognosis and increases the risk of chronic kidney failure (CKD). It is a common complication of organ failure in hospitalised patients (10-15% of all hospitalizations) and in intensive care unit (ICU) patients, with an incidence of up to 50%. Concerning ICU, AKI has a mortality rate ranging from 27% to 35%, rising to 60%-65% when dialysis is needed, with roughly 5%-20% of survivors requiring dialysis on discharge. AKI is believed to cause over 7 million deaths per year worldwide. Currently, there is no treatment for AKI or its progression to CKD. When activated by AKI, numerous pathways have been suggested as possible contributors to CKD progression. Wnt/β-catenin is a crucial regulator of kidney development that increases following the injury. Despite the overwhelming evidence that Wnt/β-catenin promotes AKI, tubulointerstitial fibrosis, a hallmark of CKD progression, is also promoted by this pathway. The therapeutic potential of Wnt/β-catenin in the treatment of AKI and the progression from AKI to CKD is being studied. This hypothesis aims to determine whether the Wnt/β-catenin inhibitor pyrvinium has a beneficial effect on the renal dysfunction and damage caused by Gentamicin.

Network pharmacology and molecular docking approach to elucidate the mechanisms of Liuwei Dihuang pill in diabetic osteoporosis

Background

Diabetic osteoporosis (DOP) is one of the chronic complications of diabetes mellitus, but without a standardized treatment plan till now. Liuwei Dihuang pill (LDP) has gradually exerted a remarkable effect on DOP in recent years; its specific mechanism is not clear yet.

Methods

We adopted network pharmacology approaches, including multi-database search, pharmacokinetic screening, network construction analysis, gene ontology enrichment analysis, Kyoto Encyclopedia of Genes and Genomes pathway analysis and molecular docking to elaborate the active components, signaling pathways and potential mechanisms of LDP in the treatment of DOP.

Results

Twenty-seven active ingredients and 55 related disease targets have been found through integrated network pharmacology. Functional enrichment analysis shows that five key active ingredients, including beta-sitosterol, stigmasterol, diosgenin, tetrahydroalstonine, and kadsurenone, may give full scope to insulin secretion estrogen-level raising and angiogenesis in biological process through the pivotal targets. In addition, the underlying effect of PI3K/AKT/FOXO and VEGF pathways is also suggested in the treatment.

Conclusion

Based on systematic network pharmacology methods, we predicted the basic pharmacological effects and potential mechanisms of LDP in the treatment of DOP, revealing that LDP may treat DOP through multiple targets and multiple signaling pathways, which provide evidence for the further study of pharmacological mechanism and broader clinical thinking.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13018-022-03194-2.

Episodic alcohol exposure attenuates mesenchymal stem cell chondrogenic differentiation during bone fracture callus formation

BACKGROUND

During bone fracture repair, mesenchymal stem cells (MSC) differentiate into chondrocytes and osteoblasts to form a fracture callus. Our laboratory previously reported that alcohol-exposed rodents with a surgically created tibia fracture display deficient fracture callus formation and diminished signs of endochondral ossification characterized by the absence of chondrocytes and mature hypertrophic chondrocytes, suggesting that alcohol may inhibit MSC differentiation. These findings led to our hypothesis that alcohol exposure inhibits mesenchymal stem cell chondrogenic differentiation within the developing fracture callus.

METHODS

In the present study, we utilized a lineage-tracing approach to determine which stage(s) of chondrogenic differentiation are affected by alcohol exposure. We utilized lineage-specific reporter mice to determine the effects of alcohol on MSC and early and late chondrogenic cell frequencies within the fracture callus. In addition, serially sectioned slides were stained immunofluorescently and immunohistochemically and quantified to determine the effect of alcohol on cell proliferation and apoptosis, respectively, within the fracture callus of alcohol-administered rodents.

RESULTS

Alcohol-administered rodents had a reduced fracture callus area at 4, 6, and 9 days postfracture. Alcohol had no effect on apoptosis in the fracture callus at any of the examined timepoints. Alcohol-administered rodents had significantly fewer proliferative cells in the fracture callus at 9 days postfracture, but no effect on cell proliferation was observed at earlier fracture callus timepoints. Alcohol-administered rodents had reduced Collagen2a1- and Collagen10a1-expressing cells in the developing fracture callus, suggesting that alcohol inhibits both early chondrogenic differentiation and later chondrocyte maturation during fracture callus development.

CONCLUSION

The data suggest that alcohol could affect normal fracture healing through the mitigation of MSC chondrogenic differentiation at the callus site.

ROS-Influenced Regulatory Cross-Talk With Wnt Signaling Pathway During Perinatal Development

Over a century ago, it was found that a rapid burst of oxygen is needed and produced by the sea urchin oocyte to activate fertilization and block polyspermy. Since then, scientific research has taken strides to establish that Reactive Oxygen Species (ROS), besides being toxic effectors of cellular damage and death, also act as molecular messengers in important developmental signaling cascades, thereby modulating them. Wnt signaling pathway is one such developmental pathway, which has significant effects on growth, proliferation, and differentiation of cells at the earliest embryonic stages of an organism, apart from being significant role-players in the instances of cellular transformation and cancer when this tightly-regulated system encounters aberrations. In this review, we discuss more about the Wnt and ROS signaling pathways, how they function, what roles they play overall in animals, and mostly about how these two major signaling systems cross paths and interplay in mediating major cellular signals and executing the predestined changes during the perinatal condition, in a systematic manner.

Naringin Alleviates H2O2-Inhibited Osteogenic Differentiation of Human Adipose-Derived Stromal Cells via Wnt/β-Catenin Signaling

Osteoporosis is an age-related systemic bone disease that places a heavy burden on patients and society. In this study, we aimed to investigate the effects of naringin (NAR) on the osteogenic differentiation of human adipose-derived stromal cells (ADSCs). The results demonstrated that NAR pretreatment effectively abated H2O2-induced cell death and ROS accumulation in ADSCs undergoing osteogenic differentiation (ADSCs-OD). In addition, we also observed that the impaired extracellular matrix mineralization and ALP activity in H2O2-stimulated ADSCs-OD were notably rescued by NAR pretreatment. Moreover, the effects of H2O2 exposure on Wnt/β-catenin signaling in ADSCs-OD were largely reversed by NAR pretreatment. Collectively, our findings indicated that NAR could protect ADSCs-OD against H2O2-inhibited osteogenic differentiation.

Plasma Fluorescent Oxidation Products and Bone Mineral Density Among Male Veterans: A Cross-Sectional Study

In vitro and vivo studies indicate that oxidative stress contributes to bone loss. Fluorescent oxidation products (FlOPs) are novel biomarkers of oxidative stress; they reflect global oxidative damage of lipids, proteins, carbohydrates, and DNA. However, whether FlOPs are associated with bone mineral density (BMD) is still unclear. In the present study, we examined the association between FlOPs and BMD among male veterans. This cross-sectional study was conducted among participants recruited from the Department of Medical Examination, The Second Hospital of Jilin University in Jilin, China. We identified male veterans who were at least 50 y old between June and October of 2019. Plasma FlOPs were measured with a fluorescent microplate reader (excitation/emission wavelength: 320/420 nm). BMD were measured by dual-energy X-ray absorptiometry (DXA). The association between FlOPs and BMD was tested by multivariable linear regression models. A total of 164 male veterans were enrolled in the study, the average age was 56.6 y. After adjusting for covariates, veterans who had FlOP levels in the highest tertile had a statistically significant lower femoral neck (β = -0.044; p = 0.007) and total hip BMD (β = -0.045; p = 0.020) as compared to those with FlOP levels in the lowest tertile. Similar results were found when FlOPs were treated as a continuous variable (per 1-SD increase, β = -0.014 and p = 0.033 for femoral neck BMD; β = -0.016 and p = 0.047 for total hip BMD). Higher FlOP levels were associated with lower BMD among male veterans.

Integrative Analysis of Exosomal miR-452 and miR-4713 Downregulating NPY1R for the Prevention of Childhood Obesity

Neuropeptides are associated with childhood obesity and exploring their regulatory mechanisms may reveal new insights for novel treatments. Childhood obesity data were downloaded from the GEO database and were used to screen for differentially expressed neuropeptides in patients with obesity. NPY1R expression was significantly upregulated in children with obesity compared to children without obesity (p < 0.05). The GEO database was used to filter differentially expressed miRNAs in patients with obesity. And hsa-mir-4713 and hsa-mir-452 were found significantly downregulated in adipose tissue. The GEO, TRRUST, and TFacts databases were used to screen all transcription factors for differentially expressed genes (DEGs). The potential regulatory networks between the differentially expressed miRNAs, TFs, and neuropeptides were mapped. In the constructed NPY1R regulatory network, the transcription factors TCF4, HEY1, and GATA3 are significantly associated with NPY1R. TCF4 and HEY1 were positively correlated with NPY1R, while GATA3 was negatively correlated with NPY1R. In the clinical peripheral blood samples, NPY1R, TCF4, and HEY1 were significantly more expressed in the obesity and the obesity with fracture group compared to the control group, while there was no statistically significant difference between the obesity group and the obesity with fracture group in terms of expression. The expression of GATA3, miR-452, and miR-4713 was also significantly lower in the obesity and the obesity with fracture groups when compared to the NC group. Therefore, NPY1R, TCF4, HEY1, GATA3, miR-452, and miR-4713 may be risk factors for fracture in obese children. The potential NPY1R regulatory function was exerted by two pathways: positive regulation caused by TCF4 and HEY1 acting on miR-4713 and negative regulation via GATA3 acting on miR-452. Potential NPY1R-related targets for the treatment of childhood obesity were provided in this study.

Understanding Reactive Oxygen Species in Bone Regeneration: A Glance at Potential Therapeutics and Bioengineering Applications

Although the complex mechanism by which skeletal tissue heals has been well described, the role of reactive oxygen species (ROS) in skeletal tissue regeneration is less understood. It has been widely recognized that a high level of ROS is cytotoxic and inhibits normal cellular processes. However, with more recent discoveries, it is evident that ROS also play an important, positive role in skeletal tissue repair, specifically fracture healing. Thus, dampening ROS levels can potentially inhibit normal healing. On the same note, pathologically high levels of ROS cause a sharp decline in osteogenesis and promote nonunion in fracture repair. This delicate balance complicates the efforts of therapeutic and engineering approaches that aim to modulate ROS for improved tissue healing. The physiologic role of ROS is dependent on a multitude of factors, and it is important for future efforts to consider these complexities. This review first discusses how ROS influences vital signaling pathways involved in the fracture healing response, including how they affect angiogenesis and osteogenic differentiation. The latter half glances at the current approaches to control ROS for improved skeletal tissue healing, including medicinal approaches, cellular engineering, and enhanced tissue scaffolds. This review aims to provide a nuanced view of the effects of ROS on bone fracture healing which will inspire novel techniques to optimize the redox environment for skeletal tissue regeneration.

Concurrence of osteonecrosis and steroid myopathy secondary to oral steroid therapy in a patient with ABCB1 gene polymorphisms: A case report

Glucocorticoids (GCs) are widely used in various autoimmune diseases. Side effects may occur in patients with long-term or high-dose GC usage. Among them, steroid myopathy and osteonecrosis are two severe forms. We report a patient with pemphigus vulgaris on GC-treatment who developed muscle weakness when a cumulative dose of methylprednisolone reached about 20g (14-80mg/d for 2.5 years). Laboratory tests showed slightly elevated lactate dehydrogenase and hydroxybutyrate dehydrogenase. MRI revealed osteonecrosis in the femoral head, distal femur, and proximal tibia of both legs. The biopsy of the right quadriceps revealed atrophy of type II myofiber without leukocyte infiltration, which was suggestive of steroid myopathy. Genotyping of the patient showed 5G/5G genotype of the PAI-1 gene and CC genotype of the ABCB1 gene (C3435T), suggesting she was sensitive to GCs. The patient's lesions were considered to be GC-induced adverse events, which were improved with tapering GC. Therefore, it is important to recognize steroid-induced musculoskeletal side effects and genotyping favors personalized medication.

Mesenchymal Stem Cell Senescence and Osteogenesis

Mesenchymal stem cells (MSCs) are stem cells with the potential ability to differentiate into various cells and the ability to self-renew and resemble fibroblasts. These cells can adhere to plastic to facilitate the culture process. MSCs can be used in research into tissue biotechnology and rejuvenation medicine. MSCs are also beneficial in recipient tissue and differentiate as a breakthrough strategy through paracrine activity. Many databases have shown MSC-based treatment can be beneficial in the reduction of osteogenesis induced by senescence. In this article, we will discuss the potential effect of MSCs in senescence cells related to osteogenesis.

Stimulation of the Runx2 P1 promoter by collagen-derived dipeptide prolyl-hydroxyproline bound to Foxg1 and Foxo1 in osteoblasts

Collagen-derived dipeptide prolyl-hydroxyproline (Pro-Hyp) directly binds to the forkhead box g1 (Foxg1) protein and causes it to undergo structural alteration. Pro-Hyp also promotes the production of a regulator of osteoblast differentiation, Runt-related transcription factor 2 (Runx2), through Foxg1, inducing osteoblast differentiation. In addition, Pro-Hyp disrupts the interaction between Foxg1 and Runx2, and Foxg1 appears to interact with Runx2 in the absence of Pro-Hyp. To elucidate the mechanism of Pro-Hyp that promotes osteoblast differentiation, we investigated whether Pro-Hyp regulates the Runx2 P1 promoter together with Foxg1. The present study revealed that Pro-Hyp is taken up by osteoblastic cells via the solute carrier family 15 member (Slc15a) 4. In the presence of Pro-Hyp, Runx2 is translocated from the nucleus to the cytoplasm and Foxg1 is translocated from the cytoplasm to the nucleus. We also found that Pro-Hyp promoted the interaction between Forkhead box o1 (Foxo1) and Runx2 and the dissociation of Foxg1 from Runx2. Moreover, we identified the Pro-Hyp response element in the Runx2 distal P1 promoter at nt −375 to −316, including the Runx2 binding sites and Fox core sequence. In the presence of Pro-Hyp, Runx2 is dissociated from the Pro-Hyp response element in the Runx2 distal P1 promoter. Subsequently, Foxg1 and Foxo1 activated the Runx2 promoter by binding to the Pro-Hyp response element. In summary, we delineated the mechanism by which Pro-Hyp stimulates the bone-related Runx2 distal P1 promoter activity in osteoblastic cells through Foxg1, Foxo1, and Runx2.

The role of forkhead box class O1 during implant osseointegration

FOXO1, a member of the forkhead family of transcription factors, plays a vital role in the osteogenic lineage commitment of mesenchymal stem cells, and affects multiple cellular functions of osteogenic cells. However, prior studies have focused on mesenchymal stem cells but not on differentiated osteoblasts. In addition, studies about the role of FOXO1 during osseointegration are lacking. In this present study, we constructed osteoblast conditional FOXO1 knock-out mice and lentivirus-mediated FoxO1 overexpression to investigate maxillary titanium implant osseointegration. After 4 wk post implant placement, micro-computed tomography, histomorphometric analyses, and RT-qPCR assays were performed. Results showed that compared with the control group, overexpression of FOXO1 significantly enhanced bone formation around implant and bone-implant contact ratio, while loss of FOXO1 impaired peri-implant osteogenesis and osseointegration. Moreover, overexpression of FoxO1 enhanced expression of osteogenesis-related genes, such as Runx2, Alp1, Col1a1, and Bglap. Whereas, knock-out of Foxo1 reduced the expression of osteogenesis-related genes. Taken together, our results suggested that FOXO1 in osteoblasts could enhance osteogenesis-related gene expression to improve osseointegration.

FoxO3a cooperates with RUNX1 to promote chondrogenesis and terminal hypertrophic of the chondrogenic progenitor cells

FoxO transcription factors (FoxOs) have recently been shown to protect against chondrocyte dysfunction and modulate cartilage homeostasis in osteoarthritis. The mechanism underlying of FoxOs regulate chondrocyte differentiation remains unknown. Runt related transcription factor 1 (RUNX1) mediated both chondrocyte and osteoblast differentiation. Our data showed that FoxO3a and RUNX1 are co-expressed in ATDC5 cells and undifferentiated mesenchyme cells and have similar high levels in chondrocytes undergoing transition from proliferation to hypertrophy. Overexpression of FoxO3a in ATDC5 cells or mouse mesenchymal cells resulted in a potent induction of the chondrocyte differentiation markers. Knockdown FoxO3a or RUNX1 potently inhibits the expressions of chondrocyte differentiation markers, including Sox9, Aggrecan, Col2, and hypertrophic chondrocyte markers including RUNX2, ColX, MMP13 and ADAMTs-5 in ATDC5 cells. Co-immunoprecipitation showed that FoxO3a binds the transcriptional regulator RUNX1. Immunohistochemistry showed that FoxO3a and RUNX1 are highly co-expressed in the proliferative chondrocytes of the growth plates in the hind limbs of newborn mice. Collectively, we revealed that FoxO3a cooperated with RUNX1 promoted chondrocyte differentiation through enhancing both early chondrogenesis and terminal hypertrophic of the chondrogenic progenitor cells, indicating FoxO3a interacting with RUNX1 may be a therapeutic target for the treatment of osteoarthritis and other bone diseases.

PKD1 alleviates oxidative stress-inhibited osteogenesis of rat bone marrow-derived mesenchymal stem cells through TAZ activation

Oxidative stress is known to inhibit osteogenesis and PKD1 is implicated in bone remodeling and skeletogenesis. In the present study, we explored the role of PKD1 in osteogenesis under oxidative stress. H2 O2 was used to induce oxidative stress in rat bone marrow (BM)-mesenchymal stem cells (MSCs) during osteoblast differentiation. Alkaline phosphatase (ALP) activity, calcium deposits, and the RUNX2 marker were assayed to determine osteogenic differentiation. The correlation of PKD1, Sirt1, c-MYC, and TAZ was further confirmed by chromatin immunoprecipitation (ChIP) and dual-luciferase reporter assay. We found that H2 O2 induced the downregulation of PKD1 expression and the upregulation of c-MYC, and Sirt1 was accompanied by decreasing cell viability in BM-MSCs. During osteogenic differentiation, the expression of PKD1 was upregulated significantly whereas Sirt1 tended to be upregulated mildly under normal conditions. Both PKD1 and Sirt1 were upregulated upon oxidative stress. The positive correlation of PKD1 expression with osteogenic differentiation under normal conditions might be hindered by oxidative stress and PKD1 could interact with TAZ under oxidative stress to regulate osteogenic differentiation. Our results suggest that PKD1 may alleviate oxidative stress-inhibited osteogenesis of rat BM-MSCs through TAZ activation.

Insights into oxidative stress in bone tissue and novel challenges for biomaterials

The presence of Reactive Oxygen Species (ROS) in bone can influence resident cells behaviour as well as the extra-cellular matrix composition and the tissue architecture. Aging, in addition to excessive overloads, unbalanced diet, smoking, predisposing genetic factors, lead to an increase of ROS and, if it is accompanied with an inappropriate production of scavengers, promotes the generation of oxidative stress that encourages bone catabolism. Furthermore, bone injuries can be triggered by numerous events such as road and sports accidents or tumour resection. Although bone tissue possesses a well-known repair and regeneration capacity, these mechanisms are inefficient in repairing large size defects and bone grafts are often necessary. ROS play a fundamental role in response after the implant introduction and can influence its success. This review provides insights on the mechanisms of oxidative stress generated by an implant in vivo and suitable ways for its modulation. The local delivery of active molecules, such as polyphenols, enhanced bone biomaterial integration evidencing that the management of the oxidative stress is a target for the effectiveness of an implant. Polyphenols have been widely used in medicine for cardiovascular, neurodegenerative, bone disorders and cancer, thanks to their antioxidant and anti-inflammatory properties. In addition, the perspective of new smart biomaterials and molecular medicine for the oxidative stress modulation in a programmable way, by the use of ROS responsive materials or by the targeting of selective molecular pathways involved in ROS generation, will be analysed and discussed critically.

The regulation mechanism of LINC00707 on the osteogenic differentiation of human periodontal ligament stem cells

The osteogenic differentiation of periodontal ligament stem cells (PDLSCs) is important for periodontal tissue repair and regeneration. Long non-coding RNAs (lncRNAs) are key regulators of diverse biological processes. However, their roles in PDLSC osteogenic differentiation are still largely unknown. This study explored the effect of LINC00707 and its mechanism on the osteogenic differentiation of human PDLSCs. Results showed an increase in LINC00707 and forkhead box O1 (FOXO1) but a decrease in miR-490-3p during PDLSC osteogenic differentiation. LINC00707 and FOXO1 promoted osteogenic differentiation as evidenced by the formation of calcium nodules and the increase in osteogenic markers such as alkaline phosphatase, osteocalcin (OCN), and runt-related transcription factor 2 (Runx2). LINC00707 and FOXO1 knockdown exhibited opposite effects. Dual-luciferase reporter assay and qRT-PCR showed that LINC00707 can specially bind to miR-490-3p, which reversed the effect of LINC00707 on PDLSCs. MiR-490-3p inhibitor relieved the inhibiting effect of sh-LINC00707 on osteogenic differentiation. Further investigation revealed that LINC00707 can promote osteogenic differentiation by regulating FOXO1 expression through miR-490-3p sponging. Thus, the LINC00707/miR-490-3p/FOXO1 axis modulated PDLSC osteogenic differentiation and might be a promising therapeutic target for periodontal diseases.

Damaged brain accelerates bone healing by releasing small extracellular vesicles that target osteoprogenitors

Clinical evidence has established that concomitant traumatic brain injury (TBI) accelerates bone healing, but the underlying mechanism is unclear. This study shows that after TBI, injured neurons, mainly those in the hippocampus, release osteogenic microRNA (miRNA)-enriched small extracellular vesicles (sEVs), which targeted osteoprogenitors in bone to stimulate bone formation. We show that miR-328a-3p and miR-150-5p, enriched in the sEVs after TBI, promote osteogenesis by directly targeting the 3'UTR of FOXO4 or CBL, respectively, and hydrogel carrying miR-328a-3p-containing sEVs efficiently repaires bone defects in rats. Importantly, increased fibronectin expression on sEVs surface contributes to targeting of osteoprogenitors in bone by TBI sEVs, thereby implying that modification of the sEVs surface fibronectin could be used in bone-targeted drug delivery. Together, our work unveils a role of central regulation in bone formation and a clear link between injured neurons and osteogenitors, both in animals and clinical settings.

Anti-proliferative, pro-apoptotic and anti-invasive effect of the copper coordination compound Cas III-La through the induction of reactive oxygen species and regulation of Wnt/β-catenin pathway in glioma

Gliomas are the most aggressive neoplasms that affect the central nervous system, being glioblastoma multiforme (GBM) the most malignant. The resistance of GBM to therapies is attributed to its high rate of cell proliferation, angiogenesis, invasion, and resistance to apoptosis; thus, finding alternative therapeutic approaches is vital. In this work, the anti-proliferative, pro-apoptotic, and anti-invasive effect of the copper coordination compound Casiopeina III-La (Cas III-La) on human U373 MG cells was determined in vitro and in vivo. Our results indicate that Cas III-La exerts an anti-proliferative effect, promoting apoptotic cell death and inactivating the invasive process by generating reactive oxygen species (ROS), inactivating GSK3β, activating JNK and ERK, and promoting the nuclear accumulation of β-catenin. The inhibition of ROS generation by N-acetyl-l-cysteine not only recovered cell migration and viability, but also reduced β-catenin accumulation and JNK and ERK activation. Additionally, Cas III-La significantly reduced tumor volume, cell proliferation and mitotic indices, and increased the apoptotic index in mice xenotransplanted with U373 glioma cells. Thus, Cas III-La is a promising agent to treat GBM.

Physiologic Mechanical Stress Directly Induces Bone Formation by Activating Glucose Transporter 1 (Glut 1) in Osteoblasts, Inducing Signaling via NAD+-Dependent Deacetylase (Sirtuin 1) and Runt-Related Transcription Factor 2 (Runx2)

Mechanical stress is an important factor affecting bone tissue homeostasis. We focused on the interactions among mechanical stress, glucose uptake via glucose transporter 1 (Glut1), and the cellular energy sensor sirtuin 1 (SIRT1) in osteoblast energy metabolism, since it has been recognized that SIRT1, an NAD+-dependent deacetylase, may function as a master regulator of the mechanical stress response as well as of cellular energy metabolism (glucose metabolism). In addition, it has already been demonstrated that SIRT1 regulates the activity of the osteogenic transcription factor runt-related transcription factor 2 (Runx2). The effects of mechanical loading on cellular activities and the expressions of Glut1, SIRT1, and Runx2 were evaluated in osteoblasts and chondrocytes in a 3D cell-collagen sponge construct. Compressive mechanical loading increased osteoblast activity. Mechanical loading also significantly increased the expression of Glut1, significantly decreased the expression of SIRT1, and significantly increased the expression of Runx2 in osteoblasts in comparison with non-loaded osteoblasts. Incubation with a Glut1 inhibitor blocked mechanical stress-induced changes in SIRT1 and Runx2 in osteoblasts. In contrast with osteoblasts, the expressions of Glut1, SIRT1, and Runx2 in chondrocytes were not affected by loading. Our present study indicated that mechanical stress induced the upregulation of Glut1 following the downregulation of SIRT1 and the upregulation of Runx2 in osteoblasts but not in chondrocytes. Since SIRT1 is known to negatively regulate Runx2 activity, a mechanical stress-induced downregulation of SIRT1 may lead to the upregulation of Runx2, resulting in osteoblast differentiation. Incubation with a Glut1 inhibitor the blocked mechanical stress-induced downregulation of SIRT1 following the upregulation of Runx2, suggesting that Glut1 is necessary to mediate the responses of SIRT1 and Runx2 to mechanical loading in osteoblasts.

Depression and Antidepressants During Pregnancy: Craniofacial Defects Due to Stem/Progenitor Cell Deregulation Mediated by Serotonin

Depression is a common and debilitating mood disorder that increases in prevalence during pregnancy. Worldwide, 7 to 12% of pregnant women experience depression, in which the associated risk factors include socio-demographic, psychological, and socioeconomic variables. Maternal depression could have psychological, anatomical, and physiological consequences in the newborn. Depression has been related to a downregulation in serotonin levels in the brain. Accordingly, the most commonly prescribed pharmacotherapy is based on selective serotonin reuptake inhibitors (SSRIs), which increase local serotonin concentration. Even though the use of SSRIs has few adverse effects compared with other antidepressants, altering serotonin levels has been associated with the advent of anatomical and physiological changes in utero, leading to defects in craniofacial development, including craniosynostosis, cleft palate, and dental defects. Migration and proliferation of neural crest cells, which contribute to the formation of bone, cartilage, palate, teeth, and salivary glands in the craniofacial region, are regulated by serotonin. Specifically, craniofacial progenitor cells are affected by serotonin levels, producing a misbalance between their proliferation and differentiation. Thus, it is possible to hypothesize that craniofacial development will be affected by the changes in serotonin levels, happening during maternal depression or after the use of SSRIs, which cross the placental barrier, increasing the risk of craniofacial defects. In this review, we provide a synthesis of the current research on depression and the use of SSRI during pregnancy, and how this could be related to craniofacial defects using an interdisciplinary perspective integrating psychological, clinical, and developmental biology perspectives. We discuss the mechanisms by which serotonin could influence craniofacial development and stem/progenitor cells, proposing some transcription factors as mediators of serotonin signaling, and craniofacial stem/progenitor cell biology. We finally highlight the importance of non-pharmacological therapies for depression on fertile and pregnant women, and provide an individual analysis of the risk-benefit balance for the use of antidepressants during pregnancy.

mRNA and long non-coding RNA expression profiling of human periodontal ligament cells under tension loading

Objective

This study explored the expression profiles of messenger RNAs (mRNAs) and long non-coding RNAs (lncRNAs) in human periodontal ligament (PDL) cells subjected to tensile loading.

Methods

PDL cells were isolated from the teeth of five healthy individuals, cultured and then exposed to tensile loading. RNA sequencing was performed to explore the mRNA and lncRNA expression profiles with or without tensile loading. Differential expression, Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses were conducted to reveal enriched biological functions and signal transduction pathways. Quantitative polymerase chain reaction (qPCR) was performed to validate the expression of specific mRNAs and lncRNAs associated with the enriched pathways.

Results

Tensile loading significantly enhanced the osteogenic potential of PDL cells. Overall, 1438 mRNAs (860 up- and 578 down-regulated) and 195 lncRNAs (107 up- and 88 down-regulated) were differentially expressed (adjusted P-value <0.05) in the tensile loading group versus the control group. GO and KEGG analyses of the differentially expressed genes indicated significant enrichment in osteogenesis-related biological processes and intracellular signal transduction pathways (e.g. the PI3K–Akt pathway), respectively. The qPCR analysis validated the expression levels of five selected mRNAs (EGFR, FGF5, VEGFA, HIF1A, and FOXO1) and three selected lncRNAs (CYTOR, MIR22HG, and SNHG3).

Limitation

Further studies are warranted to validate the mechanisms regulating tension-induced bone remodelling in PDL cells and potential regulation by the identified lncRNAs.

Conclusion

The notably altered mRNA and lncRNA expression profiles in PDL cells under tensile loading enhance our mechanistic understanding of tension-induced osteogenesis.

FOXO1 expression in chondrocytes modulates cartilage production and removal in fracture healing

Fracture healing is a multistage process characterized by inflammation, cartilage formation, bone deposition, and remodeling. Chondrocytes are important in producing cartilage that forms the initial anlagen for the hard callus needed to stabilize the fracture site. We examined the role of FOXO1 by selective ablation of FOXO1 in chondrocytes mediated by Col2α1 driven Cre recombinase. Experimental mice with lineage-specific FOXO1 deletion (Col2α1Cre⁺FOXO1^L/L) and negative control littermates (Col2α1Cre^-FOXO1^L/L) were used for in vivo, closed fracture studies. Unexpectedly, we found that in the early phases of fracture healing, FOXO1 deletion significantly increased the amount of cartilage formed, whereas, in later periods, FOXO1 deletion led to a greater loss of cartilage. FOXO1 was functionally important as its deletion in chondrocytes led to diminished bone formation on day 22. Mechanistically, the early effects of FOXO1 deletion were linked to increased proliferation of chondrocytes through enhanced expression of cell cycle genes that promote proliferation and reduced expression of those that inhibit it and increased expression of cartilage matrix genes. At later time points experimental mice with FOXO1 deletion had greater loss of cartilage, enhanced formation of osteoclasts, increased IL-6 and reduced numbers of M2 macrophages. These results identify FOXO1 as a transcription factor that regulates chondrocyte behavior by limiting the early expansion of cartilage and preventing rapid cartilage loss at later phases.

FOXO3 Mediates Tooth Movement by Regulating Force-Induced Osteogenesis

The high prevalence of malocclusion and dentofacial malformations means that the demand for orthodontic treatments has been increasing rapidly. As the biological basis of orthodontic treatment, the mechanism of mechanical force-induced alveolar bone remodeling during orthodontic tooth movement (OTM) has become the key scientific issue of orthodontics. It has been demonstrated that bone mesenchymal stem cells (BMSCs) are crucial for bone remodeling and exhibit mechanical sensing properties. Mechanical force can promote osteoblastic differentiation of BMSCs and osteogenesis, but the key factor that mediates mechanical force-induced osteogenesis during OTM remains unclear. In this study, by performing reverse-phase protein arrays on BMSCs exposed to mechanical force, we found that the expression level of forkhead box O3 (FOXO3) was significantly upregulated during the mechanical force-induced osteoblastic differentiation of BMSCs. The number of FOXO3-positive cells was consistently higher on the OTM side as compared with the control side and accompanied by the enhancement of osteogenesis. Remarkably, inhibiting FOXO3 with repaglinide delayed OTM by severely impairing mechanical force-induced bone formation in vivo. Moreover, knockdown of FOXO3 effectively inhibited the mechanical force-induced osteoblastic differentiation of BMSCs, whereas the overexpression of FOXO3 enhanced this effect. Mechanistically, we revealed a novel regulatory model in which FOXO3 promoted osteocalcin transcription by activating its promoter in cooperation with runt-related transcription factor 2 (RUNX2). We collectively obtained the first evidence that FOXO3 is critical for OTM, where it responds to mechanical force and directly regulates downstream osteoblastic differentiation in an efficient manner.

Loss of Wnt16 Leads to Skeletal Deformities and Downregulation of Bone Developmental Pathway in Zebrafish

Wingless-type MMTV integration site family, member 16 (wnt16), is a wnt ligand that participates in the regulation of vertebrate skeletal development. Studies have shown that wnt16 can regulate bone metabolism, but its molecular mechanism remains largely undefined. We obtained the wnt16^−/− zebrafish model using the CRISPR-Cas9-mediated gene knockout screen with 11 bp deletion in wnt16, which led to the premature termination of amino acid translation and significantly reduced wnt16 expression, thus obtaining the wnt16^−/− zebrafish model. The expression of wnt16 in bone-related parts was detected via in situ hybridization. The head, spine, and tail exhibited significant deformities, and the bone mineral density and trabecular bone decreased in wnt16^−/− using light microscopy and micro-CT analysis. RNA sequencing was performed to explore the differentially expressed genes (DEGs). Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis found that the down-regulated DEGs are mainly concentrated in mTOR, FoxO, and VEGF pathways. Protein–protein interaction (PPI) network analysis was performed with the detected DEGs. Eight down-regulated DEGs including akt1, bnip4, ptena, vegfaa, twsg1b, prkab1a, prkab1b, and pla2g4f.2 were validated by qRT-PCR and the results were consistent with the RNA-seq data. Overall, our work provides key insights into the influence of wnt16 gene on skeletal development.

Molecular Interactions between Dietary Lipids and Bone Tissue during Aging

Age-related bone disorders such as osteoporosis or osteoarthritis are a major public health problem due to the functional disability for millions of people worldwide. Furthermore, fractures are associated with a higher degree of morbidity and mortality in the long term, which generates greater financial and health costs. As the world population becomes older, the incidence of this type of disease increases and this effect seems notably greater in those countries that present a more westernized lifestyle. Thus, increased efforts are directed toward reducing risks that need to focus not only on the prevention of bone diseases, but also on the treatment of persons already afflicted. Evidence is accumulating that dietary lipids play an important role in bone health which results relevant to develop effective interventions for prevent bone diseases or alterations, especially in the elderly segment of the population. This review focuses on evidence about the effects of dietary lipids on bone health and describes possible mechanisms to explain how lipids act on bone metabolism during aging. Little work, however, has been accomplished in humans, so this is a challenge for future research.

Wnt/β-Catenin in Acute Kidney Injury and Progression to Chronic Kidney Disease

Acute kidney injury (AKI) portends a poor clinical prognosis and increases the risk for the development of chronic kidney disease (CKD). Currently, there are no therapies to treat AKI or prevent its progression to CKD. Wnt/β-catenin is a critical regulator of kidney development that is up-regulated after injury. Most of the literature support a beneficial role for Wnt/β-catenin in AKI, but suggest that this pathway promotes the progression of tubulointerstitial fibrosis, the hallmark of CKD progression. We review the role of Wnt/β-catenin in renal injury with a focus on its potential as a therapeutic target in AKI and in AKI to CKD transition.

A decrease in NAD+ contributes to the loss of osteoprogenitors and bone mass with aging

Age-related osteoporosis is caused by a deficit in osteoblasts, the cells that secrete bone matrix. The number of osteoblast progenitors also declines with age associated with increased markers of cell senescence. The forkhead box O (FoxO) transcription factors attenuate Wnt/β-catenin signaling and the proliferation of osteoprogenitors, thereby decreasing bone formation. The NAD⁺-dependent Sirtuin1 (Sirt1) deacetylates FoxOs and β-catenin in osteoblast progenitors and, thereby, increases bone mass. However, it remains unknown whether the Sirt1/FoxO/β-catenin pathway is dysregulated with age in osteoblast progenitors. We found decreased levels of NAD⁺ in osteoblast progenitor cultures from old mice, associated with increased acetylation of FoxO1 and markers of cell senescence. The NAD⁺ precursor nicotinamide riboside (NR) abrogated FoxO1 and β-catenin acetylation and several marker of cellular senescence, and increased the osteoblastogenic capacity of cells from old mice. Consistent with these effects, NR administration to C57BL/6 mice counteracted the loss of bone mass with aging. Attenuation of NAD⁺ levels in osteoprogenitor cultures from young mice inhibited osteoblastogenesis in a FoxO-dependent manner. In addition, mice with decreased NAD⁺ in cells of the osteoblast lineage lost bone mass at a young age. Together, these findings suggest that the decrease in bone formation with old age is due, at least in part, to a decrease in NAD⁺ and dysregulated Sirt1/FoxO/β-catenin pathway in osteoblast progenitors. NAD⁺ repletion, therefore, represents a rational therapeutic approach to skeletal involution.

The Roles of FOXO1 in Periodontal Homeostasis and Disease

Periodontitis is an oral chronic inflammatory disease that is initiated by periodontal microbial communities and requires disruption of the homeostatic responses. The prevalence of periodontal disease increases with age; more than 70% of adults 65 years and older have periodontal disease. A pathogenic microbial community is required for initiating periodontal disease. Dysbiotic immune-inflammatory response and bone remodeling are characteristics of periodontitis. The transcription factor forkhead box protein O1 (FOXO1) is a key regulator of a number of cellular processes, including cell survival and differentiation, immune status, reactive oxygen species (ROS) scavenging, and apoptosis. Although accumulating evidence indicates that FOXO1 activity can be induced by periodontal pathogens, the roles of FOXO1 in periodontal homeostasis and disease have not been well documented. The present review summarizes how the FOXO1 signaling axis can regulate periodontal bacteria-epithelial interactions, immune-inflammatory response, bone remodeling, and wound healing.

PERK signaling pathway in bone metabolism: Friend or foe?

Osteoblasts and osteoclasts participate in the process of bone remodelling to meet the needs of normal growth and development or repair pathological damage. Endoplasmic reticulum stress (ER stress) can break the intracellular homeostasis of osteoclasts and osteoblasts, which is closely related to abnormal bone remodelling. The double‐stranded RNA‐dependent protein kinase (PKR)‐like ER kinase (PERK) is a key transmembrane protein that regulates ER stress, and growing evidence suggests that the PERK pathway plays a crucial role in regulating bone metabolism under both physiological and pathological conditions. Based on the current findings, we summarized the main mechanisms involved in bone metabolism downstream of the PERK pathway, among which elF2α, FOXO1, CaN, Nrf2 and DAG play a role in regulating the differentiation of osteoblasts and osteoclasts. Importantly, strategies by the regulation of PERK pathway exert beneficial effects in preclinical trials of several bone‐related diseases. Given the importance and novelty of PERK pathway, we provide an overview and discuss the roles of PERK pathway in regulating bone metabolism and its impact on bone‐related diseases. We hope that the development of research in this field will bring a bright future for the treatment of bone‐related diseases.

Moringa oleifera leaf extracts protect BMSC osteogenic induction following peroxidative damage by activating the PI3K/Akt/Foxo1 pathway

Objective

We aimed to investigate the therapeutic effects of Moringa oleifera leaf extracts on osteogenic induction of rat bone marrow mesenchymal stem cells (BMSCs) following peroxidative damage and to explore the underlying mechanisms.

Methods

Conditioned medium was used to induce osteogenic differentiation of BMSCs, which were treated with H₂O₂, Moringa oleifera leaf extracts-containing serum, or the phosphatidyl inositol-3 kinase (PI3K) inhibitor wortmannin, alone or in combination. Cell viability was measured using the MTT assay. Cell cycle was assayed using flow cytometry. Expression levels of Akt, phosphorylated (p)Akt, Foxo1, and cleaved caspase-3 were analyzed using western blot analysis. The mRNA levels of osteogenesis-associated genes, including alkaline phosphatase (ALP), collagen І, osteopontin (OPN), and Runx2, were detected using qRT-PCR. Reactive oxygen species (ROS) and malondialdehyde (MDA) levels, as well as superoxide dismutase (SOD), glutathione peroxidase (GSH-PX), and ALP activity were detected using commercially available kits. Osteogenic differentiation capability was determined using alizarin red staining.

Results

During osteogenic induction of rat BMSCs, H₂O₂ reduced cell viability and proliferation, inhibited osteogenesis, increased ROS and MDA levels, and decreased SOD and GSH-PX activity. H₂O₂ significantly reduced pAkt and Foxo1 expression, and increased cleaved caspase-3 levels in BMSCs. Additional treatments with Moringa oleifera leaf extracts partially reversed the H₂O₂-induced changes. Wortmannin partially attenuated the effects of Moringa oleifera leaf extracts on protein expression of Foxo1, pAkt, and cleaved caspase-3, as well as mRNA levels of osteogenesis-associated genes.

Conclusion

Moringa oleifera leaf extracts ameliorate peroxidative damage and enhance osteogenic induction of rat BMSCs by activating the PI3K/Akt/Foxo1 pathway.

Effects of titanium with different micro/nano structures on the ability of osteoblasts to resist oxidative stress

Excessive accumulation of oxidative intermediates in the elderly significantly aggravates bone degradation and hinders the osseointegration of topological titanium (Ti) implants. Thus, it is of great significance to evaluate the antioxidant and osteoinduction capabilities of various nano, micro or micro/nano-composite structures under oxidative stress (OS) microenvironment. In this study, we discovered that 110 nm titania nanotubes (TNTs) enhanced the adsorption of fibronectin (FN) proteins onto smooth and rough titanium surfaces to varying degrees. Compared with Ti and 30 nm TNTs (T₃₀) groups, cells on 110 nm TNTs (T₁₁₀), microstructure/30 nm TNTs (M₃₀) and microstructure/110 nm TNTs (M₁₁₀) had smaller area, lower reactive oxygen species (ROS), and better proliferation/osteogenic differentiation abilities under OS condition, but there was no significant difference among the three groups. In addition, combined with our previous study, we suggested that T₁₁₀, M₃₀ and M₁₁₀ resistance to OS was also strongly associated with the high expression of FN-receptor integrin α5 or β1. All the findings indicated that the micro/nano-composed structures (M₃₀ & M₁₁₀) had similar anti-oxidation and osteogenesis abilities to T₁₁₀, which provided guidance for the application of different titanium implants with different topologies in the elderly.

Molecular characterisation of osteoblasts from bone obtained from people of Polynesian and European ancestry undergoing joint replacement surgery

Population studies in Aotearoa New Zealand found higher bone mineral density and lower rate of hip fracture in people of Polynesian ancestry compared to Europeans. We hypothesised that differences in osteoblast proliferation and differentiation contribute to the differences in bone properties between the two groups. Osteoblasts were cultured from bone samples obtained from 30 people of Polynesian ancestry and 25 Europeans who had joint replacement surgeries for osteoarthritis. The fraction of cells in S-phase was determined by flow cytometry, and gene expression was analysed by microarray and real-time PCR. We found no differences in the fraction of osteoblasts in S-phase between the groups. Global gene expression analysis identified 79 differentially expressed genes (fold change > 2, FDR P < 0.1). Analysis of selected genes by real-time PCR found higher expression of COL1A1 and KRT34 in Polynesians, whereas BGLAP, DKK1, NOV, CDH13, EFHD1 and EFNB2 were higher in Europeans (P ≤ 0.01). Osteoblasts from European donors had higher levels of late differentiation markers and genes encoding proteins that inhibit the Wnt signalling pathway. This variability may contribute to the differences in bone properties between people of Polynesian and European ancestry that had been determined in previous studies.

Resveratrol prevents steroid-induced osteonecrosis of the femoral head via miR-146a modulation

The purpose of this study was to investigate the possible use of resveratrol (Res) to reverse abnormal osteogenesis/osteoclastogenesis activity that occurs during femoral head osteonecrosis and to explore the detailed mechanisms. Application of Res to bone marrow-derived mesenchymal stem cells in vitro promoted survival, inhibited apoptosis, and downregulated expression of reactive oxygen species expression. Moreover, Res application was associated with elevated microRNA-146a (miR-146a) expression, osteogenic differentiation, and suppressed osteoclastic differentiation, which were markedly reversed by miR-146a inhibitor. Histopathological observations and micro-computed tomography scanning results indicated that the Res-treated group had lower incidence of osteonecrosis and better bone microstructure than the untreated group. Res inhibited osteoclastogenesis through altering the levels of sirtuin1 (Sirt1), nuclear transcription factor-κB (NF-κB), and receptor activator of NF-κB ligand (RANKL). Simultaneously, Res treatment improved bone formation and increased β-catenin and runt-related transcription factor 2 (Runt2) expression levels, while reducing forkhead box class O (FOXO) family protein levels. The results of our study suggest that Res prevents steroid-induced osteonecrosis by upregulating miR-146a, and thereby stabilizes osteogenesis/osteoclastogenesis homeostasis via Wnt/FOXO and Sirt1/NF-κB pathways.

The Role of Forkhead Box Family in Bone Metabolism and Diseases

Forkhead box (Fox) family, an evolutionarily conserved family of transcription factors carrying the "Forkhead" motif, plays an indispensable role in human health and disease. Fox family genes are involved in cell differentiation, proliferation and apoptosis, embryonic development, aging, glucose and lipid metabolism, and immune regulation. The regulatory role of the Fox family in the context of bone metabolism and orthopedic diseases is an emerging research hotspot. In this review, we highlight the major molecular mechanisms underlying the regulatory role of Fox factors in bone metabolism, bone development, bone homeostasis, and bone diseases associated with inhibition or upregulation of Fox factors. In addition, we discuss the emerging evidence in the realm of Fox factor-based therapeutics.