Mitochondrial dysfunction and therapeutic perspectives in osteoporosis

A-485 alleviates postmenopausal osteoporosis by activating GLUD1 deacetylation through the SENP1-Sirt3 signal pathway

OBJECTIVE

Postmenopausal osteoporosis (OP) is a bone disease caused by estrogen deficiency. A-485 is a selective inhibitor of p300/CBP histone acetyltransferase (HAT) with potential regulatory effects on bone remodeling. This study aims to investigate the effects of A-485 on postmenopausal OP and its underlying mechanisms.

METHODS

For animal experiments, 61 female Wistar rats were used to establish an OP model through ovariectomy (OVX). The rats were administered with A-485 (100 mg/kg/day) via intraperitoneal injection for six weeks. Bone mineral density (BMD) was measured using dual-energy X-ray absorptiometry (DXA). Histopathological changes were observed using HE and Masson's trichrome staining. ELISA was used to measure bone resorption markers (CTX-1, DPD) and the bone formation marker (P1NP) in rats. Osteoblast differentiation markers (Runx2, OCN), SENP1, Sirt3 expression levels, and GLUD1 acetylation were assessed via Western blot (WB) and RT-qPCR. In vitro, MC3T3-E1 osteogenic progenitor cells were cultured in osteogenic differentiation medium supplemented with ascorbic acid, β-glycerophosphate, dexamethasone, and fulvestrant. CCK-8 was performed to evaluate cell proliferation. Flow cytometry was selected to measure apoptosis and mitochondrial membrane potential. WB and RT-qPCR were employed to analyze ERα, ERβ, Runx2, Sirt3, and GLUD1 acetylation. Additionally, Alizarin red staining was applied to monitor osteoblast mineralization. ATP levels were detected using a commercial kit, and ROS levels were measured by MitoSOX Red.

RESULTS

In vivo, ovariectomized rats exhibited lower BMD, impaired bone trabeculae, increased CTX-1 and DPD, and altered expression of Runx2 and OCN, all of which were reversed by A-485 treatment. In vitro, A-485 activated GLUD1 deacetylation, enhanced osteogenic differentiation, and improved mitochondrial function. Regarding the mechanism, A-485 activated the SENP1-Sirt3 signal pathway, with SENP1 knockdown negating the effects of A-485. In vivo, A-485 reduced GLUD1 acetylation and promoted improvement of OP, which were reversed by SENP1 knockdown.

CONCLUSION

A-485 ameliorates postmenopausal OP by activating GLUD1 deacetylation via the SENP1-Sirt3 signal pathway, thus improving mitochondrial function, and promoting osteogenic differentiation and mineralization.

Emerging nanomaterials capable of effectively facilitating osteoblast maturation

Efficient osteoblast maturation is essential for successful bone regeneration, yet achieving this goal remains challenging. This review explores the emerging role of nanomaterials in promoting osteoblast differentiation and bone formation. A literature search was conducted in the Web of Science Core Collection in February 2025, covering publications from 2014 to 2024 and limited to articles and proceedings. Keywords included "nanoparticles" and "osteoblast." Among the most extensively studied nanomaterials were hydroxyapatite, carbon-based, and bioactive glass nanoparticles (NPs). These materials influence osteoblast function through intracellular mechanisms, including enhanced mitochondrial activity, autophagy, and osteoinductive gene expression. Additionally, they modulate the extracellular microenvironment by mimicking the native bone matrix, releasing bioactive ions, and reducing inflammation and oxidative stress. Notably, several NP-based systems have reached clinical application, including Signafuse (a bioactive calcium phosphate composite), nanoLOCK (a nanostructured titanium spinal implant), and Vitoss (a synthetic bone graft of nanocrystalline calcium phosphate). More recently, multimodal NPs that integrate different NP types and combine surface roughness, ion release, and chemical cues offer synergistic effects. These materials provide a dual-function approach, targeting both intracellular processes and the bone microenvironment. Their ability to modulate inflammation, oxidative stress, and cellular signaling underscores their translational potential in regenerative medicine and bone tissue engineering.

SNX10 functions as a modulator of piecemeal mitophagy and mitochondrial bioenergetics

We here identify the endosomal protein SNX10 as a negative regulator of piecemeal mitophagy of OXPHOS machinery components. In control conditions, SNX10 localizes to early endocytic compartments in a PtdIns3P-dependent manner and modulates endosomal trafficking but also shows dynamic connections with mitochondria. Upon hypoxia-mimicking conditions, SNX10 localizes to late endosomal structures containing selected mitochondrial proteins, including COX-IV and SAMM50, and the autophagy proteins SQSTM1/p62 and LC3B. The turnover of COX-IV was enhanced in SNX10-depleted cells, with a corresponding reduced mitochondrial respiration and citrate synthase activity. Importantly, zebrafish larvae lacking Snx10 show reduced levels of Cox-IV, as well as elevated ROS levels and ROS-mediated cell death in the brain, demonstrating the in vivo relevance of SNX10-mediated modulation of mitochondrial bioenergetics.

Engineered Extracellular Vesicles Derived from Juvenile Mice Enhance Mitochondrial Function in the Aging Bone Microenvironment and Achieve Rejuvenation

Aging-related bone degeneration and impaired healing capacity remain significant challenges in regenerative medicine, necessitating innovative, efficient, and targeted strategies to restore bone health. Here, we engineered extracellular vesicles (EVs) derived from the serum of pretreated juvenile mice, with the goals of reversing aging, enhancing osteogenic potential, and increasing bioavailability to rejuvenate the aging bone environment. First, we established bone healing models representing different phases of healing to identify the EV type with the highest potential for improving the bone microenvironment in older individuals. Second, we employed DSS6 for bone targeting to enhance the biological effects of the selected EVs in vivo. The engineered EVs effectively targeted bone repair sites and promoted fracture healing more effectively than unmodified EVs in older mice. RNA sequencing revealed that the translocase of outer mitochondrial membrane 7 (Tomm7) is crucial for the underlying mechanism. Silencing Tomm7 significantly diminished the positive regulatory effects of the EVs. Specifically, the engineered EVs may enhance mitochondrial function in aging cells by activating the Tomm7-mediated Pink1/Parkin mitophagy pathway, promoting stemness recovery in aging bone marrow stromal cells (BMSCs) and reversing the adverse conditions of the aging bone microenvironment. Overall, the developed engineered EVs derived from serum from juvenile mice offer an alternative approach for treating aging bones. The identified underlying biological mechanisms provide a valuable reference for precision treatment of aging bones in the future.

Identification of a Novel Mitochondrial-Related Gene Signature for BMSCs in Osteoporosis Combining Single-Cell and Bulk Transcriptome Data

Osteoporosis (OS) is a prevalent skeletal disorder characterized by reduced bone mass and increased fracture risk, often linked to compromised functions of bone mesenchymal stem cells (BMSCs). Mitochondrial dysfunction and aberrant mitophagy are implicated in OS pathogenesis. This study aimed to identify a novel mitochondrial-related gene signature in BMSCs from OS patients by integrating single-cell and bulk transcriptome data. We analyzed single-cell RNA sequencing data from GSE147287 and bulk transcriptome data from GSE35956 to identify differentially expressed mitochondrial-related genes (MRGs) in BMSCs between healthy individuals and OS patients. Key genes were identified using LASSO logistic regression and random forest algorithms, and their differential expression was validated by RT-qPCR, Western blot, and immunofluorescence. Functional assays, including osteogenic differentiation and β-galactosidase staining, were conducted following siRNA-mediated knockdown of DUT. We identified 28 differentially expressed MRGs, with four key genes (DUT, UQCR10, DNAJC4, and MRPL33) further confirmed. Electron microscopy scanning showed damage to BMSCs mitochondria and decreased osteogenic differentiation ability in OS. Silencing DUT significantly impairs the mitochondrial function and osteogenic differentiation ability of BMSCs, indicating its potential role in OS development. This study identifies a mitochondrial gene signature in BMSCs linked to osteoporosis, with DUT emerging as a key regulator. DUT silencing impairs mitochondrial function and osteogenic differentiation, suggesting it as a potential therapeutic target for OS.

Cuproptosis and its potential role in musculoskeletal disease

Cuproptosis, a recently identified form of copper-dependent cell death, arises from intracellular copper dyshomeostasis. As an essential trace element, copper plays a critical role in bioenergetic metabolism, redox regulation, and synaptic transmission. However, excessive copper exerts cytotoxic effects through multiple pathways, including increased reactive oxygen species (ROS) production, apoptotic cascade activation, necrotic membrane rupture, inflammatory responses, and mitochondrial dysfunction. Distinct from other cell death mechanisms, cuproptosis is characterized by copper ion binding to acetylated mitochondrial respiratory chain proteins, leading to pathogenic protein aggregation, iron-sulfur cluster depletion, and cellular collapse. Emerging evidence underscores aberrant copper accumulation and resultant proteotoxic stress as pivotal contributors to the pathogenesis of multiple musculoskeletal pathologies, including osteoporosis, osteoarthritis, sarcopenia, osteosarcoma, intervertebral disc degeneration, spinal cord injury, and biofilm-associated orthopedic infections. Understanding the spatiotemporal regulation of cuproptosis may provide novel opportunities for advancing diagnostic and therapeutic approaches in orthopedic medicine. This review synthesizes current insights into the molecular mechanisms of cuproptosis, its pathogenic role in musculoskeletal diseases, and the potential for biomarker-driven therapeutic interventions.

Antioxidant scaffolds for enhanced bone regeneration: recent advances and challenges

Bone regeneration is integral to maintaining bone function and integrity in the body, as well as treating bone diseases, such as osteoporosis and defects. However, oxidative stress often poses a significant obstacle during bone regeneration, leading to cell damage, inflammatory responses, and subsequent impediment of normal bone tissue formation. Therefore, to maintain bone regeneration, antioxidant therapy is essential. Bone scaffolds, serving as a temporary support for bone tissue, can provide an ideal microenvironment for cell proliferation and differentiation, effectively promoting bone tissue formation. In recent years, with in-depth research on antioxidants and their mechanisms of action, the development and application of antioxidant bone scaffolds have shown tremendous potential. These antioxidant bone scaffolds not only promote osteogenic differentiation and angiogenesis, but also effectively inhibit the inflammatory response and osteoclast formation, significantly improving the efficiency of bone regeneration. Notably, with the rapid development of nanotechnology, nanozymes with multi-enzyme-like activities have been successfully constructed and encapsulated within bone scaffolds, leading to the proposal of multifunctional antioxidant strategies. Therefore, this review summarizes recent research progress, categorically introducing types of bone scaffolds and antioxidants, elucidating therapeutic strategies of antioxidant bone scaffolds, and identifying current challenges, aiming to provide valuable guidance for subsequent research.

Mitochondrial Dysfunction and Its Potential Molecular Interplay in Hypermobile Ehlers-Danlos Syndrome: A Scoping Review Bridging Cellular Energetics and Genetic Pathways

Hypermobile Ehlers-Danlos Syndrome (hEDS) is a hereditary connective tissue disorder characterized by joint hypermobility, skin hyperextensibility, and systemic manifestations such as chronic fatigue, gastrointestinal dysfunction, and neurological symptoms. Unlike other EDS subtypes with known genetic mutations, hEDS lacks definitive markers, suggesting a multifactorial etiology involving both mitochondrial dysfunction and non-mitochondrial pathways. This scoping review, conducted in accordance with the PRISMA-ScR guidelines, highlights mitochondrial dysfunction as a potential unifying mechanism in hEDS pathophysiology. Impaired oxidative phosphorylation (OXPHOS), elevated reactive oxygen species (ROS) levels, and calcium dysregulation disrupt cellular energetics and extracellular matrix (ECM) homeostasis, contributing to the hallmark features of hEDS. We reviewed candidate genes associated with ECM remodeling, signaling pathways, and immune regulation. Protein-protein interaction (PPI) network analyses revealed interconnected pathways linking mitochondrial dysfunction with these candidate genes. Comparative insights from Fabry disease and fragile X premutation carriers underscore shared mechanisms such as RNA toxicity, matrix metalloproteinases (MMP) activation, and ECM degradation. These findings may suggest that mitochondrial dysfunction amplifies systemic manifestations through its interplay with non-mitochondrial molecular pathways. By integrating these perspectives, this review provides a potential framework for understanding hEDS pathogenesis while highlighting latent avenues for future research into its molecular basis. Understanding the potential role of mitochondrial dysfunction in hEDS not only sheds light on its complex molecular etiology but also opens new paths for targeted interventions.

Identification of endoplasmic reticulum stress and mitochondrial dysfunction related biomarkers in osteoporosis

BACKGROUND

Endoplasmic reticulum stress (ERS) and mitochondrial dysfunction (MD) involved in bone metabolism disorders. However, the particular mechanisms of ERS and MD related genes (ERS&MDRGs) in osteoporosis (OP) have not been elucidated. In present study, biomarkers related to ERS and MD in OP were identified.

METHODS

Differentially expressed genes (DEGs) were obtained based on GEO dataset. ERS&MDRGs were derived from Genecard database. Initially, ERS&MD related DEGs (ERS&MDRDEGs) were obtained by overlapping DEGs and ERS&MDRGs. The key module was screened by WGCNA. The intersection of ERS&MDRDEGs and key module was screened by machine learning to obtain key genes. Then, receiver operating characteristic curve (ROC) was drawn to calculated diagnostic accuracy of key genes. The ssGSEA and Cibersort algorithms were performed to analyze immune cell infiltration. The miRNA-mRNA-TF network were draw by cytoscape software. Moleculaer docking and DGIdb database were employed for screening potential drugs. Finally, the expression of key genes was verified by qRT-PCR.

RESULTS

The 122 ERS&MDRDEGs were obtained by preliminary screening. ERS&MDRDEGs were mainly enriched in lipid metabolism, calcium ion transport, and ossification. The 5 key genes were identified, including AAAS, ESR1, SLC12A2, TAF15, and VAMP2. Immune infiltration analysis showed monocyte and macrophage were different between OP and control groups. The miRNA-mRNA-TF regulatory network indicated has-miR-625-5p, has-miR-296-3p, CTCT and EP300 as potential regulatory targets. The 2 potential small molecule drugs, namely bumetanide and elacestrant were screened. The expression of AAAS, ESR1, VAMP2 were higher, and SLC12A2 and TAF15 were lower in OP than control group.

CONCLUSION

This research identified 5 key genes AAAS, ESR1, SLC12A2, TAF15 and VAMP2. Bumetanide and elacestrant were potential drugs. These findings provided valuable insights into the pathophysiology of OP and the development of new therapeutic strategies.

Interruption of mitochondrial symbiosis is associated with the development of osteoporosis

Mitochondria maintain bacterial traits because of their endosymbiotic origins, yet the host cell recognizes them as non-threatening since the organelles are compartmentalized. Nevertheless, the controlled release of mitochondrial components into the cytoplasm can initiate cell death, activate innate immunity, and provoke inflammation. This selective interruption of endosymbiosis as early as 2 billion years ago allowed mitochondria to become intracellular signaling hubs. Recent studies have found that the interruption of mitochondrial symbiosis may be closely related to the occurrence of various diseases, especially osteoporosis (OP). OP is a systemic bone disease characterized by reduced bone mass, impaired bone microstructure, elevated bone fragility, and susceptibility to fracture. The interruption of intra-mitochondrial symbiosis affects the energy metabolism of bone cells, leads to the imbalance of bone formation and bone absorption, and promotes the occurrence of osteoporosis. In this paper, we reviewed the mechanism of mitochondrial intersymbiosis interruption in OP, discussed the relationship between mitochondrial intersymbiosis interruption and bone marrow mesenchymal stem cells, osteoblasts and osteoclasts, as well as the inheritance and adaptation in the evolutionary process, and prospected the future research direction to provide new ideas for clinical treatment.

Are Dietary Patterns Relevant for Reducing the Risk of Fractures and Sarcopenia?

PURPOSE OF REVIEW

This review aims to summarise recent evidence on the effects of dietary patterns on the risk of bone fractures and sarcopenia.

RECENT FINDINGS

Several dietary patterns have been investigated in relation to musculoskeletal health, including Mediterranean Dietary Patterns (MDP), Dietary Inflammatory Indices, vegetarian and vegan diets. Adherence to 'healthier' dietary patterns appears to be protective against fractures and sarcopenia, with the strongest protective associations found between the MDP and fractures. Individuals following vegan or vegetarian eating patterns need to be aware of calcium and vitamin D requirements to maintain musculoskeletal health. Although more healthy dietary patterns may be protective for musculoskeletal health the current evidence base is limited by variation in the construction of dietary pattern scores and reported outcome measures. Future research should fully report scoring methods, intakes of dietary components across scoring groups or categories, and consider outcome measures that allow for better comparison between studies.

Association between life's essential 8 and bone mineral density among adults aged 20-59 years

This study investigates the relationship between Life's Essential 8 (LE8) scores and bone mineral density (BMD) in adults aged 20-59 years. This cross-sectional analysis employed nationally representative data from NHANES 2011-2018. Weighted multiple linear regression models were applied to assess the association between LE8 scores and varying levels of cardiovascular health (CVH) with BMD. Subgroup analyses were performed to evaluate differences in the impact of LE8 scores on BMD across age groups, genders, races, socioeconomic statuses, and BMI categories. The study included 2159 participants. After adjusting for all covariates, LE8 scores demonstrated a significant positive linear association with lumbar spine BMD, thoracic spine BMD, trunk BMD, and total BMD. Individuals in the medium and high CVH groups exhibited higher BMD compared to those in the low CVH group. Subgroup analyses indicated that the association was more evident in participants aged 20-35 years and among those with normal BMI. In females, thoracic spine BMD appeared particularly sensitive to changes in LE8 scores. This study identifies a positive linear relationship between LE8 scores and BMD. Higher CVH scores were linked to greater BMD in adults aged 20-59 years. These findings highlight the importance of adopting comprehensive health strategies, suggesting that improving CVH may contribute to maintaining bone density and supporting skeletal health.

ECSIT: Biological function and involvement in diseases

Evolutionary conserved signaling intermediate in Toll pathways (ECSIT), a multi-functional protein, was first identified as a cytosolic adaptor protein in Toll-like receptors (TLRs) signaling-mediated innate immune responses. In the past two decades, studies have expanded the understanding of ECSIT. Nevertheless, there are still large knowledge gaps due to the inadequate number of studies regarding ECSIT, especially an overall review of ECSIT is lacking. Here, we first comprehensively summarize the biological functions of ECSIT with particular focus on innate immune responses and mitochondrial homeostasis. Cumulative studies have reinforced that ECSIT is involved in the regulation of innate immune responses through activating NF-κB signaling and potentiating the Retinoic acid-induced gene Ⅰ (RIG-Ⅰ)/ mitochondrial antiviral- signaling protein (MAVS) pathway-mediated innate antiviral immunity. In addition, ECSIT determines the mitochondrial morphology and function including mitochondrial complex Ⅰ (CⅠ) assembly, mitochondrial reactive oxygen species (mROS) production, mitochondrial membrane potential (MMP) maintenance and mitochondrial quality control. Owing to these distinct functions, ECSIT is involved in the etiology and pathology of human diseases including Alzheimer's disease (AD), cardiac hypertrophy, musculoskeletal disintegration, cancer, extranodal natural killer/T cell lymphoma (ENKTL) and ischemic stroke. Collectively, the roles and mechanisms of ECSIT under physiological and pathological conditions are critically discussed to provide a clearer view of the therapeutic potential of ECSIT.

Screening of genes co-associated with osteoporosis and chronic HBV infection based on bioinformatics analysis and machine learning

Objective

To identify HBV-related genes (HRGs) implicated in osteoporosis (OP) pathogenesis and develop a diagnostic model for early OP detection in chronic HBV infection (CBI) patients.

Methods

Five public sequencing datasets were collected from the GEO database. Gene differential expression and LASSO analyses identified genes linked to OP and CBI. Machine learning algorithms (random forests, support vector machines, and gradient boosting machines) further filtered these genes. The best diagnostic model was chosen based on accuracy and Kappa values. A nomogram model based on HRGs was constructed and assessed for reliability. OP patients were divided into two chronic HBV-related clusters using non-negative matrix factorization. Differential gene expression analysis, Gene Ontology, and KEGG enrichment analyses explored the roles of these genes in OP progression, using ssGSEA and GSVA. Differences in immune cell infiltration between clusters and the correlation between HRGs and immune cells were examined using ssGSEA and the Pearson method.

Results

Differential gene expression analysis of CBI and combined OP dataset identified 822 and 776 differentially expressed genes, respectively, with 43 genes intersecting. Following LASSO analysis and various machine learning recursive feature elimination algorithms, 16 HRGs were identified. The support vector machine emerged as the best predictive model based on accuracy and Kappa values, with AUC values of 0.92, 0.83, 0.74, and 0.7 for the training set, validation set, GSE7429, and GSE7158, respectively. The nomogram model exhibited AUC values of 0.91, 0.79, and 0.68 in the training set, GSE7429, and GSE7158, respectively. Non-negative matrix factorization divided OP patients into two clusters, revealing statistically significant differences in 11 types of immune cell infiltration between clusters. Finally, intersecting the HRGs obtained from LASSO analysis with the HRGs identified three genes.

Conclusion

This study successfully identified HRGs and developed an efficient diagnostic model based on HRGs, demonstrating high accuracy and strong predictive performance across multiple datasets. This research not only offers new insights into the complex relationship between OP and CBI but also establishes a foundation for the development of early diagnostic and personalized treatment strategies for chronic HBV-related OP.

Identification and experimental validation of programmed cell death- and mitochondria-associated biomarkers in osteoporosis and immune microenvironment

Background: Prior research has demonstrated that programmed cell death (PCD) and mitochondria assume pivotal roles in controlling cellular metabolism and maintaining bone cell equilibrium. Nonetheless, the comprehensive elucidation of their mode of operation in osteoporosis (OP) warrants further investigation. Therefore, this study aimed at analyzing the role of genes associated with PCD (PCD-RGs) and mitochondria (mortality factor-related genes; MRGs) in OP. Methods: Differentially expressed genes (DEGs) were identified by subjecting the GSE56815 dataset obtained from the Gene Expression Omnibus database to differential expression analysis and comparing OP patients with healthy individuals. The genes of interest were ascertained through the intersection of DEGs, MRGs, and PCD-RGs; these genes were filtered using machine learning methodologies to discover potential biomarkers. The prospective biomarkers displaying uniform patterns and statistically meaningful variances were identified by evaluating their levels in the GSE56815 dataset and conducting quantitative real-time polymerase chain reaction-based assessments. Moreover, the functional mechanisms of these biomarkers were further delineated by constructing a nomogram, which conducted gene set enrichment analysis, explored immune infiltration, generated regulatory networks, predicted drug responses, and performed molecular docking analyses. Results: Eighteen candidate genes were documented contingent upon the intersection between 2,354 DEGs, 1,136 MRGs, and 1,548 PCD-RGs. The biomarkers DAP3, BIK, and ACAA2 were upregulated in OP and were linked to oxidative phosphorylation. Furthermore, the predictive ability of the nomogram designed based on the OP biomarkers exhibited a certain degree of accuracy. Correlation analysis revealed a strong positive correlation between CD56dim natural killer cells and ACAA2 and a significant negative correlation between central memory CD4+ T cells and DAP3. DAP3, BIK, and ACAA2 were regulated by multiple factors; specifically, SETDB1 and ZNF281 modulated ACAA2 and DAP3, whereas TP63 and TFAP2C governed DAP3 and BIK. Additionally, a stable binding force was observed between the drugs (estradiol, valproic acid, and CGP52608) and the biomarkers. Conclusion: This investigation evidenced that the biomarkers DAP3, BIK, and ACAA2 are associated with PCD and mitochondria in OP, potentially facilitate the diagnosis of OP in clinical settings.