Secreted phosphoprotein 1 (SPP1), also known as osteopontin, is a multifunctional glycoprotein that plays a critical role in various physiological processes, including cell adhesion, chemotaxis, immune regulation, and tissue remodeling. Originally identified as a key component of the bone matrix, SPP1 is now recognized for its broad involvement in numerous tissues and significant impact on both normal physiology and disease progression. Dysregulation of SPP1 has been strongly implicated in the pathogenesis and progression of several diseases, including cancer, cardiovascular diseases, autoimmune disorders, and chronic inflammatory conditions. The expression of SPP1 is tightly regulated by genetic and nongenetic mechanisms. Genetic alterations, such as single-nucleotide polymorphisms, insertions and deletions, and structural variations within the SPP1 gene, have been associated with increased susceptibility to various diseases, influencing disease severity and outcomes. Additionally, nongenetic regulations, including DNA methylation, histone modifications, and long noncoding RNAs, play crucial roles in modulating SPP1 expression in response to environmental and cellular signals. This review provides a comprehensive overview of the genetic and nongenetic regulatory mechanisms governing SPP1 and examines their implications in disease pathogenesis. By integrating recent findings, this review highlights the complex interplay between genetic predispositions and nongenetic regulations in determining SPP1 activity and offers new insights into its role as a potential biomarker and therapeutic target. Understanding these regulatory pathways is essential for the development of targeted interventions for diseases in which SPP1 plays a pivotal role.

Osteonecrosis of the femoral head (ONFH) is a debilitating orthopedic disease characterized by femoral head collapse and destruction of bone and articular cartilage, resulting in severe joint pain and loss of hip mobility. Bone marrow mesenchymal stem cells (BMSCs) exhibit multilineage differentiation potential, including osteoblasts, adipocytes, fibroblasts, chondrocytes, and neurocytes. The imbalance between osteogenesis and adipogenesis in BMSCs plays a critical role in ONFH pathogenesis. Factors such as alcohol consumption and glucocorticoid exposure promote adipogenic differentiation while inhibiting osteogenic differentiation, leading to excessive adipocyte accumulation, reduced bone formation, and vascular impairment. We highlight the molecular mechanisms underlying ONFH with a particular focus on the role of BMSCs and further discuss the involvement of adipocytes. Moreover, we suggest that the use of adipose-derived mesenchymal stem cells (ADMSCs) is a viable approach for stem cell therapy and may have immense potential in ONFH. Several signaling pathways, including the Wnt, TGFβ/BMP, and PI3K/AKT pathways, along with various RNAs and other regulators, govern the osteogenesis and adipogenesis of BMSCs. These signaling pathways target essential transcription factors, such as Runx2 for osteogenesis and PPARγ and C/EBPs for adipogenesis. Adipocytes and their secreted adipokines, including leptin and adiponectin, strongly influence ONFH progression. Emerging therapies involving ADMSCs show potential for promoting bone regeneration and neovascularization. Our review provides a comprehensive overview of the current understanding of ONFH mechanisms by focusing on mesenchymal stem cells and adipocytes and suggests future research directions for therapeutic interventions.

Calcium phosphate (Ca-P) ceramics are promising bioactive material that can be used for the remodeling and regeneration of bone tissue. However, it's sintering temperature-dependent mechanical strength, which is negatively correlated with its bioactivity, causes difficulties in improving the comprehensive performance of Ca-P ceramics. Here, the femtosecond laser (FSL) with low-temperature plasma effect was adopted to modify the hydroxyapatite (HA) ceramics after high temperatures (1250 °C) sintering, pursuing higher mechanical strength along with better osteogenic activity. The changes in the physicochemical properties of the materials and the osteogenic activity were characterized and investigated. Cell evaluations and in vivo experiments were performed to assess and verify the effect of FSL processing on the osteogenic capability of HA ceramics. The results indicated that α- and β-tricalcium phosphate (TCP) multiphase components were formed on the HA ceramic surfaces after laser treatment, simultaneously bringing about surface micro-nano porous structure, accelerated release of calcium (Ca) and phosphate (Pi) ions, enhancement of roughness, hydrophilicity and surface energy. Their synergistic effect facilitated apatite precipitation on the HA surface, promoted osteogenic differentiation and osteogenic/angiogenic gene expression. In vivo results also confirmed the enhancement of HA ceramic osteogenic activity by FSL treatment. This study presents an effective strategy of introducing FSL etching to high-temperature sintered Ca-P ceramics to improve the bone regeneration of HA ceramics and attain satisfactory mechanical strength at the same time. It will further promote the clinical application of HA ceramics in the field of bone regenerative repair. STATEMENT OF SIGNIFICANCE: This study introduces a method that uses the low-temperature plasma effect of the femtosecond laser (FSL) to modify the surfaces of high-temperature sintered hydroxyapatite (HA) ceramics, enhancing their osteogenic activity while maintaining the original mechanical strength. FSL processing induces the formation of bioactive multiphase of tricalcium phosphate (α-TCP and β-TCP) on the surfaces, creates micro-nano topographies, improves hydrophilicity and surface energy, promoting osteoblast differentiation and osteogenic gene expression for faster bone regeneration. This method overcomes the issue that high-temperature sintered HA ceramics have high strength but low osteogenic activity. It provides a modification method for HA ceramics with well-characterized performance enhancements, offering a convenient and effective strategy for high quality bone regenerative repair.

Menin, the protein product of the MEN1 gene, is essential for development and has been implicated in multiple different cancer types. These include leukemias and several different solid tumors, including neuroendocrine tumors. Menin interacts with many different protein partners and genomic loci in a context-dependent manner, implicating it in numerous cellular processes. The role of Menin varies across tumor types as well, acting as a tumor suppressor in some tissues and an oncogenic co-factor in others. Given the role of Menin in cancer, and particularly its oncogenic role in acute myeloid leukemia, the development of Menin inhibitors has been an expanding field over the past 10-15 years. Many inhibitors have been in clinical trials and one has recently received approval from the Food and Drug Administration (FDA). In this review, we explore the role of Menin in multiple cancer types, the development of Menin inhibitors and their clinical applications and what the focus of the field should be in the next 5-10 years to expand the use and efficacy of these drugs.

Prostate cancer (PCa) is the most prevalent cancer among men globally. Although, there are various therapeutic methods for the localized or advanced cancers, there is still a high rate of mortality among PCa patients that is mainly associated with bone metastasis in advanced tumors. There are few options available for treating bone metastasis in PCa, which only provide symptom relief without curing the disease. Therefore, it is crucial to evaluate the molecular mechanisms associated with bone metastasis of PCa cells to suggest the novel diagnostic and therapeutic approaches that could lower the morbidity and mortality rates in PCa patients. MicroRNAs (miRNAs) are involved in regulation of various pathophysiological processes such as tumor growth and osteoblasts/osteoclasts formation. Since, miRNA deregulation has been also frequently observed in PCa patients with bone metastasis, we discussed the role of miRNAs in bone metastasis during PCa progression. It has been reported that miRNAs mainly reduced the ability of PCa tumor cells for the bone metastasis through the regulation of WNT, NF-kB, PI3K/AKT, and TGF-β signaling pathways. They also affected the EMT process, transcription factors, and structural proteins to regulate the bone metastasis during PCa progression. This review paves the way to suggest the miRNAs as the reliable markers not only for the non-invasive early diagnosis, but also for the targeted therapy of PCa tumors with bone metastasis.

Testicular microcalcifications consist of hydroxyapatite and have been associated with an increased risk of testicular germ cell tumors (TGCTs) but are also found in benign cases such as loss-of-function variants in the phosphate transporter SLC34A2. Here, we show that fibroblast growth factor 23 (FGF23), a regulator of phosphate homeostasis, is expressed in testicular germ cell neoplasia in situ (GCNIS), embryonal carcinoma (EC), and human embryonic stem cells. FGF23 is not glycosylated in TGCTs and therefore cleaved into a C-terminal fragment which competitively antagonizes full-length FGF23. Here, Fgf23 knockout mice presented with marked calcifications in the epididymis, spermatogenic arrest, and focally germ cells expressing the osteoblast marker Osteocalcin (gene name: Bglap, protein name). Moreover, the frequent testicular microcalcifications in mice with no functional androgen receptor and lack of circulating gonadotropins are associated with lower Slc34a2 and higher Bglap/Slc34a1 (protein name: NPT2a) expression compared with wild-type mice. In accordance, human testicular specimens with microcalcifications also have lower SLC34A2 and a subpopulation of germ cells express phosphate transporter NPT2a, Osteocalcin, and RUNX2 highlighting aberrant local phosphate handling and expression of bone-specific proteins. Mineral disturbance in vitro using calcium or phosphate treatment induced deposition of calcium phosphate in a spermatogonial cell line and this effect was fully rescued by the mineralization inhibitor pyrophosphate. In conclusion, testicular microcalcifications arise secondary to local alterations in mineral homeostasis, which in combination with impaired Sertoli cell function and reduced levels of mineralization inhibitors due to high alkaline phosphatase activity in GCNIS and TGCTs facilitate osteogenic-like differentiation of testicular cells and deposition of hydroxyapatite.

Runx2 is a master regulator of bone formation, and its dysfunction causes cleidocranial dysplasia (CCD) in humans. When iPS cells were generated from patients with CCD and Runx2-deficient iPS cells were generated using gene-editing techniques, abnormal laminopathy-like nuclei were observed. Runx2-deficient cells showed reduced Lamin A/C expression, but not protein levels. However, in Runx2-deficient cells, both the gene expression and protein levels of Nesprin1 were reduced, perinuclear actin fibers were sparser, and nuclear stiffness was reduced. Forced expression of Lamin A/C increased nuclear stiffness but did not improve nuclear morphology. In contrast, the induction of Nesprin1 expression alone normalized nuclear stiffness and restored nuclear morphology and perinuclear actin distribution. In Runx2-null cells, mechanical stress-induced phosphorylation of emerin was not observed. In contrast, forced expression of Nesprin1 in Runx2-null cells resulted in phosphorylation of emerin, indicating the restoration of intracellular tension. These observations were confirmed by atomic force microscopy. Therefore, the intracellular tension was inferred to pull the nuclear membrane into its normal shape. CUT&RUN assay and single RNA-seq analysis showed that an aberrant nuclear membrane caused loss of nuclear lamina gene regulation machinery, making the progression of normal osteogenic differentiation impossible; however, supplementation with Nesprin1 restored gene regulation mechanisms and promoted preosteoblast formation with normal nuclear morphology. Nesprin1 expression induced by Runx2 is essential for epigenetic regulation of the nuclear lamina. We propose CCD as a type of laminopathy involving defective expression of Nesprin1 regulated by Runx2.

The MYST family histone acetyltransferase gene, KAT6B (MYST4, MORF, QKF) is mutated in two distinct human congenital disorders characterised by intellectual disability, facial dysmorphogenesis and skeletal abnormalities; the Say-Barber-Biesecker-Young-Simpson variant of Ohdo syndrome and Genitopatellar syndrome. Despite its requirement in normal skeletal development, the cellular and transcriptional effects of KAT6B in skeletogenesis have not been thoroughly studied. Here, we show that germline deletion of the Kat6b gene in mice causes premature ossification in vivo, resulting in shortened craniofacial elements and increased bone density, as well as shortened tibias with an expanded pre-hypertrophic layer, as compared to wild type controls. Mechanistically, we show that the loss of KAT6B in mesenchymal progenitor cells promotes transition towards an osteoblast-progenitor state with upregulation of gene targets of RUNX2, a master regulator of osteoblast development and concomitant downregulation of SOX9, a critical gene in chondrocyte development. Moreover, we find that compound heterozygosity at Kat6b and Runx2 loci partially rescues the reduction in ossification of Runx2 heterozygous, but not homozygous mice, suggesting that KAT6B may limit the action of RUNX2, possibly through a role in maintaining progenitors in an undifferentiated state. Moreover, our results show that KAT6B has essential roles in regulating the expression of a large number of genes involved in skeletogenesis and bone development.

The glutamatergic signaling pathway, which is mediated by N-methyl-D-aspartate (NMDA) receptors, is crucial for osteoblast differentiation and bone function. Dextromethorphan (DXM), a widely used antitussive, is a noncompetitive antagonist of the NMDA receptor. However, the effects of DXM on osteoblast and bone regeneration remain unclear. The present study investigated the effects of DXM on osteogenesis in vitro and in vivo. A MC3T3-E1 preosteoblast cell line was treated with varying concentrations of DXM. Real-time-quantitative polymerase chain reaction (RT-qPCR) and Western-blot analysis were performed to evaluate the expression of osteogenesis-related runt-related transcription factor 2 (RUNX2), osterix (OSX), osteocalcin (OCN), collagen type 1α (Col-1α), and alkaline phosphatase (ALP) after DXM treatment. Zebrafish embryos were incubated with DXM, which had potential to affect the ossification of the vertebrae and skull, and analyzed using calcein staining. Furthermore, we used a rat calvarial defect model to assess the effects of DXM on bone regeneration by using microcomputed tomography. The results indicate that DXM inhibited extracellular mineralization, ALP activity, and the expression of osteogenic markers, namely RUNX2, OSX, OCN, Col-1α, and ALP, in MC3T3-E1 cells. DXM suppressed skeleton ossification in zebrafish and affected bone regeneration in rats with calvarial defects. However, the mineral density of the regenerated bones did not differ significantly between the DXM and control groups. The present study demonstrated that DXM negatively affects the osteogenic function of osteoblasts, leading to impaired skeletal development and bone regeneration. Thus, clinicians should consider the negative effects of DXM on bone regeneration.

Bone-substituted composite material based on bioceramics and polymer has enhanced their biological performance with dynamic properties such as bioactivity, biocompatibility, osseointegration, and mechanical stability, which can be used in a controlled drug delivery system for avoiding infections as well as pain. Here in this study, we developed a new approach for inducing antibacterial and osteogenic responses on biomaterial substrates via surface polarisation. The hydroxyapatite- sodium alginate composite was negatively polarised using a corona poling setup and characterised using X-ray diffraction analysis. The thermally stimulated depolarization current study showed a maximum current of 4.74 nA/cm2, observed at a temperature of 480 °C. The wettability of the specimen was measured using contact angle measurements, which demonstrated that the polarised composite specimen exhibited higher water retention ability. The bacterial cell viability test was measured using the 3-(4, 5-dimethylthiazolyl-2)-2, 5-diphenyltetrazolium bromide) assay, which revealed poor bacterial growth on polarised specimens as compared to their unpolarised counterparts. In addition, the osteogenic MG63 cell proliferation showed increased gene expression on polarised specimens. These findings showed that polarising hydroxyapatite- sodium alginate composite could be an excellent option to be used as an antibacterial bone filler matrix for faster healing as it showed both antibacterial and osteogenic activity.

Growing consumption of processed foods may cause a greater risk of excessive dietary phosphate intake. The increased dietary phosphate intake as a food additive in the periconceptional period may affect the children's future health. Here, we investigated the effects of maternal excess dietary phosphate intake on offspring in C57BL/6J mice. Female mice were fed a control diet (CP, 0.8% phosphate) or a high-phosphate diet (HP, 1.5% phosphate) for either 21 days during pre-pregnancy or almost 20 days during pregnancy. After weaning, offspring were raised on the CP diet. Relative to the CP groups, offspring from dams fed HP during pre-pregnancy or pregnancy showed decreased urinary phosphate excretion without significant changes in either plasma phosphate level or renal sodium-dependent phosphate transporter mRNA expression at 3 or 10 weeks. However, mRNA expression of intestinal sodium-dependent phosphate transporter was decreased, suggesting that the reduced urinary phosphate excretion was due to decreased absorption of intestinal phosphate. Interestingly, offspring in the HP groups also demonstrated significant differences in plasma levels of parathyroid hormone, fibroblast growth factor 23, and vitamin D. To our knowledge, this is the first report to show that maternal excess intake of dietary phosphate in the periconceptional period disturbs phosphate metabolism in offspring.

The aging population has led to a global issue of osteoarthritis (OA), which not only impacts the quality of life for patients but also poses a significant economic burden on society. While biotherapy offers hope for OA treatment, currently available treatments are unable to delay or prevent the onset or progression of OA. Recent studies have shown that as nanoscale bioactive substances that mediate cell communication, exosomes from stem cell sources have led to some breakthroughs in the treatment of OA and have important clinical significance. This paper summarizes the mechanism and function of stem cell exosomes in delaying OA and looks forward to the development prospects and challenges of exosomes.

This study aimed to investigate the effects of aspirin on the early stages of odontogenic differentiation. The roles of FOXC1, RUNX2, and MCAM gene expression in the mechanism of odontogenic differentiation were evaluated by examining the effects of downregulated FOXC1 or RUNX2 expression using small interfering RNAs (siRNAs).

Dental pulp cells were treated with aspirin (0, 2.5, 50, 100 μg/ml) to assess its impact on mineralization. The gene expression levels of FOXC1, RUNX2, and MCAM were measured using digital polymerase chain reaction, and the effects of siRNA-mediated knockdown of FOXC1 and RUNX2 were analyzed. The mineralization potential was quantitatively assessed using Alizarin Red S staining and a calcium assay.

Analysis of cell growth curves and doubling times indicated that aspirin did not affect cell proliferation at 2.5 μg/ml and 50 μg/ml; however, 50 μg/ml aspirin promoted mineralization. In the FOXC1 and RUNX2 knockdown experiments, fluctuations in FOXC1, RUNX2, and MCAM gene expression were observed in the aspirin-treated group, suggesting the involvement of these genes in mineralization. Alizarin red S staining and calcium assays further demonstrated that aspirin enhanced mineralization.

These findings indicate that aspirin promotes odontogenic differentiation and regulates the expression of FOXC1, RUNX2, and MCAM. This suggests that aspirin may serve as a promising new therapeutic agent in dental pulp regenerative medicine.

Loss of osteogenic differentiation potential of osteoblasts has been associated with the pathogenesis of osteoporosis. Thus, stimulation of osteoblastic differentiation is a therapeutic strategy for osteoporosis. Relaxin-2 is a peptide hormone with potent biological functions. However, the effects of Relaxin-2 in osteoblastic differentiation and osteoporosis have not been reported before. Here, we report a novel physiological role of Relaxin-2 in promoting osteoblastic differentiation and mineralization of MC3T3-E1 cells. Our results indicate that exposure to Relaxin-2 upregulated the expression, and elevated the activity of alkaline phosphatase (ALP) when MC3T3-E1 cells were cultured in osteogenic differentiation medium (OM). Additionally, Relaxin-2 upregulated the mRNA levels of osteocalcin (ocn), osteopontin (opn), and collagen type I alpha 1 (Col1a1). The alizarin red S staining assay revealed that Relaxin-2 promoted the mineralization of MC3T3-E1 cells. We also found that Relaxin-2 increased the expression of Runx-2 as well as the epidermal growth factor (EGF) and epidermal growth factor receptor (EGFR). Importantly, silencing of EGF abolished the effects of Relaxin-2 in osteoblastic differentiation and related gene expression. These findings suggest that Relaxin-2 stimulates osteogenic differentiation through activating EGF/EGFR signaling.

The periodontal ligament (PDL) is a connective tissue, and PDL cells have a potential to differentiate into cementoblasts, osteoblasts, and gingival fibroblasts. This study investigated whether transcription factor c-Myb could induce differentiation of PDL cells for periodontal regeneration. PDL cells were isolated from extracted teeth and cultured. c-Myb was transfected to PDL cells using replication-deficient adenoviral vector. Differentiation of the PDL cells was analyzed by immunoblot, alkaline phosphatase activity, Alizarin red stain, and immunofluorescence analysis. Cell viability on titanium surfaces was analyzed by crystal violet stain and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. PDL cells cultured in osteogenic medium showed increased production of osteogenic and cementogenic molecules. Moreover, c-Myb-transfected cells showed increased production of dentinogenic molecules, in addition to the osteogenic and cementogenic molecules, even in normal culture condition. c-Myb-transfected cells also exhibited increased autophagy and type I collagen production under nutrient deprivation. When grown on a titanium surface, c-Myb-transfected cells showed increased production of osteogenesis-, dentinogenesis-, and cementogenesis-related molecules and cell viability. Thus, these results suggest that c-Myb might play an essential role during periodontal regeneration by improving the differentiation of PDL cells, and c-Myb can be utilized for enhancing the attachment of PDL cells to dental implant surfaces.

Echolocation represents one of the most rapid adaptive sensorimotor modulation behaviors observed in mammals, establishing bats as one of the most evolutionarily successful mammals. Bats rely on high-frequency hearing for survival, but our understanding of its cellular molecular basis is scattered and segmented. Herein, we constructed the first single-cell transcriptomic landscape of the cochlea in Hipposideros armiger, a CF-FM bat, using a PacBio-optimized genome and compared it with the results obtained from unoptimized original genomes. Sixteen distinct cell types were distributed across five spatial regions of the cochlea. Notably, through hematoxylin and eosin staining and fluorescence in situ hybridization, we identified new types of spiral ganglion neuron (SGN) cells in the cochlea of H. armiger. These SGN cells are likely critical for auditory perception and may have driven the adaptive evolution of high-frequency hearing in this species. Furthermore, we uncovered the differentiation relationships of among specific cell types, such as the transition from supporting cells to hair cells. Using the cochlear cell atlas as a reference, cell types susceptible to deafness-associated genes (in the human) were also identified. In summary, this study provides novel insights into the cellular and molecular mechanisms underlying the adaptive high-frequency hearing in bats and highlights potential candidate cell types and genes for therapeutic interventions in hearing loss.

The delicate balance between bone formation by osteoblasts and bone resorption by osteoclasts maintains bone homeostasis. Nuclear receptors (NRs) are now understood to be crucial in bone physiology and pathology. However, the function of the Farnesoid X receptor (FXR), a member of the NR family, in regulating bone homeostasis remains incompletely understood. In this study, in vitro and in vivo models revealed delayed bone development and an osteoporosis phenotype in mice lacking FXR in bone marrow mesenchymal stem cells (BMSCs) and osteoblasts due to impaired osteoblast differentiation. Mechanistically, FXR could stabilize RUNX2 by inhibiting Thoc6-mediated ubiquitination, thereby promoting osteogenic activity in BMSCs. Moreover, activated FXR could directly bind to the Thoc6 promoter, suppressing its expression. The interaction between RUNX2 and Thoc6 was mediated by the Runt domain of RUNX2 and the WD repeat of Thoc6. Additionally, Obeticholic acid (OCA), an orally available FXR agonist, could ameliorate bone loss in an ovariectomy (OVX)-induced osteoporotic mouse model. Taken together, our findings suggest that FXR plays pivotal roles in osteoblast differentiation by regulating RUNX2 stability and that targeting FXR may be a promising therapeutic approach for osteoporosis.

Dipropyl phthalate (DPRP), a plasticizer commonly utilized in the plastics industry, has been identified in food and the environment and has the potential to present a hazard to human health and the environment. In this study, the first comprehensive evaluation of DPRP-induced craniofacial chondrogenic defects was conducted using a zebrafish model. Zebrafish embryos were exposed to 1, 2, and 4 mg/L DPRP from 6 to 96 h post-fertilization. At 80 hpf, it was observed that exposure to DPRP resulted in craniofacial developmental malformations, which were mainly characterized by the shortening of the mandibular pharyngeal arches and the inability of the accompanying artery to elongate forward. The resulting phenotype was similar to that of micrognathia syndrome. Transcriptome sequencing and molecular docking analyses revealed that DPRP down-regulated chondrocyte-related genes and induced activation of the FoxO signaling pathway, which in turn interfered with cell proliferation and apoptosis. In this process, DPRP induced elevated levels of oxidative stress in the craniofacial pharyngeal arch while promoting inflammatory responses. This ultimately led to craniofacial chondrogenic malformations in zebrafish. The present study demonstrates that DPRP induces developmental toxicity of zebrafish craniofacial cartilage, which may have adverse effects on other aquatic organisms and humans.

La-related protein 7 (LARP7) is a key regulator of RNA metabolism and is thought to play a role in various cellular processes. LARP7 gene autosomal recessive mutations are the cause of Alazami syndrome, which presents with skeletal abnormalities, intellectual disabilities, and facial dysmorphisms. This study aimed to determine the role of LARP7 in modulating gene expression dynamics during osteogenesis.

First, the temporal expression profile of the LARP7 gene during various stages of osteogenesis was examined. Then, RNA interference-mediated knockdown of LARP7 was implemented and high-throughput RNA-seq analysis was performed in order to identify global gene expression changes associated with knockdown of LARP7. The findings show there were significant alterations in the overall gene expression profile. The observed down-regulation in extracellular matrix (ECM) component genes suggests that it might lead to impairments in the structure and function of the bone matrix. Additionally, modulation of alternative splicing events were observed, especially in the RUNX2 and SPP1, indicating the potential contribution of LARP7 to the phenotypic features observed in Alazami syndrome.

Overall, the findings clarify the regulatory mechanisms of LARP7 in osteogenic differentiation and illuminate potential avenues for therapeutic interventions in patients with skeletal disorders.

We previously reported that PRDM16 mediated the improvement in body composition in testosterone (T)-treated hypogonadal men by shifting adipogenesis to myogenesis. Previous preclinical studies suggest that Prdm16 regulates Runx2, an important osteoblastic transcription factor, expression and activity. However, the changes in PRDM16, and other genes/proteins involved in osteoblastogenesis with T therapy in hypogonadal men are unexplored. We investigated the role of PRDM16 in RUNX2 activation by measuring changes in gene expression in peripheral blood monocytes (PBMCs) and proteins in the serum of hypogonadal men after T therapy for 6 months. Likewise, we evaluated changes in the WNT10b-β-CATENIN signaling pathway by gene expression and protein analyses. We found significant increases in PRDM16 and RUNX2 expression in PBMCs together with significant increases in serum proteins at 6 months when compared to baseline. There were also increases in gene and protein expressions of WNT10b, and β-CATENIN at 6 months. Furthermore, we found a significant positive correlation between % changes in PRDM16 and WNT10b. Our results suggest that T therapy activates PRDM16, leading to enhanced signaling in the canonical WNT10b-β-CATENIN-RUNX2 pathway, the pathway involved in osteoblastogenesis. The above findings may account for the improvement in bone density and quality in hypogonadal men treated with T.

Craniofacial morphogenesis depends on complex cell fate decisions during the differentiation of post-migratory cranial neural crest cells. Molecular mechanisms of cell differentiation of mesenchymal cells to developing bones, cartilage, teeth, tongue, and other craniofacial tissues are still poorly understood. We performed single-cell transcriptomic analysis of craniofacial mesenchymal cells derived from cranial NCCs in mouse embryo. Using FACS sorting of Wnt1-Cre2 progeny, we carefully mapped the cell heterogeneity in the craniofacial region during the initial stages of cartilage and bone formation. Transcriptomic data and in vivo validations identified molecular determinants of major cell populations involved in the development of lower and upper jaw, teeth, tongue, dermis, or periocular mesenchyme. Single-cell transcriptomic analysis of Meis2-deficient mice revealed critical gene expression differences, including increased osteogenic and cell adhesion markers. This leads to affected mesenchymal cell differentiation and increased ossification, resulting in impaired bone, cartilage, and tongue formation.

Osteoarthritis (OA) is a debilitating chronic joint disease affecting large populations of patients, especially the elderly. The pathological mechanisms of OA are currently unknown. Multiple risk factors are involved in OA development. Among these risk factors, alterations of mechanical loading in the joint leading to changes in biological signaling pathways have been known as a key event in OA development. The importance of AMPK-β-catenin-Runx2 signaling in the initiation and progression of OA has been recognized in recent years. In this review, we discuss the recent progress in understanding the role of this signaling pathway and the underlying interaction mechanisms during OA development. We also discuss the drug development aiming to target this signaling pathway for OA treatment.

Osteoporosis is a metabolic bone disorder characterized by low bone mass and bone mineral density. It is the most prevalent bone disease and a common cause of fracture in aging adults. Low bone mass, as seen in osteoporosis, results from an imbalance between osteoblast and osteoclast activity. Gli1+ cells are indispensable to the maintenance of bone tissue homeostasis. These cells give rise to osteoprogenitors and are present at the osteogenic fronts of long bones in adult mice. Runx2 is a key regulator of osteogenesis and plays a crucial role in osteoblastic differentiation and maturation during development. However, its function in maintaining adult bone tissue homeostasis remains unclear. In this study, we investigated the role of Runx2 in maintaining adult bone homeostasis in the context of ovariectomy-induced estrogen deficiency, a model for postmenopausal osteoporosis. Our results show that deletion of Runx2 in the Gli1+ osteogenic progenitor population prevents loss of both cortical and trabecular bone mass and mineralization after ovariectomy. At the cellular level, loss of Runx2 leads to a decrease in osteoclast activity. Our study indicates that Runx2 is essential for maintaining adult bone tissue homeostasis by regulating osteoclast differentiation.

Hedgehog and canonical Wnt signaling pathways and the transcription factors Runx2 and Sp7 are essential for osteoblast differentiation. Ihh is necessary for the commitment of perichondrial mesenchymal cells to Runx2+ osteoprogenitors and for the formation of the bone collar and primary spongiosa. Runx2 is needed for osteoblast differentiation during both endochondral and intramembranous ossification. It regulates the commitment of mesenchymal cells to osteoblast-lineage cells and their proliferation by inducing the expression of Hedgehog, Fgf, Wnt, Pthlh signaling pathway genes, and Dlx5. The Runx2-induced expression of Fgfr2 and Fgfr3 is important for the proliferation of osteoblast-lineage cells. Runx2 induces Sp7 expression and Runx2+ osteoprogenitors become Runx2+Sp7+ preosteoblasts. Runx2, Sp7, and canonical Wnt signaling induce the differentiation of preosteoblasts into osteoblasts. Canonical Wnt signaling, but not Sp7, enhances the proliferation of osteoblast-lineage cells. In mature osteoblasts, Runx2 plays an important role in the expression of major bone matrix protein genes, including Col1a1, Col1a2, Spp1, Ibsp, and Bglap/Bglap2. The canonical Wnt signaling pathway is also crucial for bone formation by mature osteoblasts. Sp7 is needed for osteocytes to acquire a sufficient number of processes and a reduction in these processes results in osteocyte apoptosis and cortical porosity.

This study demonstrates that dissolution products of inorganic/organic SiO2-CaOCME/PTHF/PCL-diCOOH hybrid (70S30CCME-CL) drive human bone marrow stromal cells (h-BMSCs) down an osteogenic pathway with the production of mineralised matrix. We investigated osteogenesis through combined analyses of mRNA dynamics for key markers and targeted staining of mineralised matrix. We demonstrate that h-BMSCs undergo accelerated differentiation in vitro in response to the 70S30CCME-CL ionic milieu, as compared to incubation with osteogenic media. Extracts from 70S30CCME-CL promote osteogenesis by inducing changes in cellular metabolic activity, promoting changes in cell morphology consistent with the osteogenic lineage, and by enhancing mineralisation of hydroxyapatite in the extracellular matrix. Additionally, our results show that 70S30CCME-CL hybrids prove sustained functional resilience by maintaining osteostimulatory effects despite cumulated dissolution cycles. In co-differentiation medium, 70S30CCME-CL ionic release can modulate signalling pathways associated with non-osteogenic functions, further supporting their potential for bone regeneration applications. Overall, our study provides compelling experimental evidence that the 70S30CCME-CL hybrid is a promising biomaterial for bone tissue regeneration applications.

Nephrocalcinosis is a common pathological finding in cats with chronic kidney disease and nephrolithiasis. Understanding its pathogenesis may identify future therapeutic targets.

Nephrocalcinosis is associated with expression of an osteogenic phenotype.

Kidneys with medullary mineralization were obtained from 18 cats (10 with and 8 without nephroliths) undergoing necropsy.

Cross-sectional study. Microradiography and histopathology (modified von Kossa stain) were used to confirm parenchymal mineralization. Immunohistochemistry for 5 osteogenic markers was performed to determine their co-localization with nephrocalcinosis. The proportion of kidneys with stronger immunointensity in mineralized versus non-mineralized regions was analyzed using 1-tailed sign tests. The proportion of kidneys with co-localization of nephrocalcinosis and each marker was compared between kidneys with and without nephroliths using Fisher's exact tests.

Nephrocalcinosis co-localized with osteopontin immunoreactivity in all 18 cats (100%) and with osteocalcin in 12 cats (67%). Both osteogenic markers had stronger immunointensity in mineralized regions compared with non-mineralized regions. Limited co-localization was observed with other markers: bone morphogenic protein-2 in 2 kidneys (both with nephroliths) and tissue non-specific alkaline phosphatase in 1 kidney (without nephroliths); runt-related transcription factor-2 was undetected. No statistically significant differences were found in the co-localization of nephrocalcinosis with osteogenic proteins between kidneys with and without nephroliths.

Expression of osteogenic proteins in areas of nephrocalcinosis indicates that nephrocalcinosis is associated with the development of an osteogenic phenotype. Targeting these processes could offer a novel approach to prevent nephrolithiasis at its origin.

Human skeletal elements are formed from distinct origins at distinct positions of the embryo. For example, the neural crest produces the facial bones, the paraxial mesoderm produces the axial skeleton, and the lateral plate mesoderm produces the appendicular skeleton. During skeletal development, different combinations of signaling pathways are coordinated from distinct origins during the sequential developmental stages. Models for human skeletal development have been established using human pluripotent stem cells (hPSCs) and by exploiting our understanding of skeletal development. Stepwise protocols for generating skeletal cells from different origins have been designed to mimic developmental trails. Recently, organoid methods have allowed the multicellular organization of skeletal cell types to recapitulate complicated skeletal development and metabolism. Similarly, several genetic diseases of the skeleton have been modeled using patient-derived induced pluripotent stem cells and genome-editing technologies. Model-based drug screening is a powerful tool for identifying drug candidates. This review briefly summarizes our current understanding of the embryonic development of skeletal tissues and introduces the current state-of-the-art hPSC methods for recapitulating skeletal development, metabolism, and diseases. We also discuss the current limitations and future perspectives for applications of the hPSC-based modeling system in precision medicine in this research field.

An improved understanding of the molecular actions underpinning bone marrow mesenchymal stem cell (BMSC) differentiation could highlight new therapeutics for osteoporosis (OP). Current evidence indicates that microRNAs (miRNAs) exert critical roles in many biological systems, including osteoblast differentiation. In this study, we examined miR-468-3p effects on osteogenic differentiation (OD). Distinct miR-468-3p reductions were identified during OD. MiR-468-3p also suppressed BMSC OD in gain- and loss-of-function assays, while it negatively regulated Runx2 as shown by molecular, protein, and bioinformatics approaches. When Runx2 was inhibited by small-interfering RNA (siRNA), the inhibitory effects of miR-468-3p toward BMSC osteogenesis were considerably reversed. Also, silenced miR-468-3p in ovariectomized (OVX) and sham mice augmented bone mass (BM) and bone formation (BF) and improved trabecular (Tb) microarchitecture. Therefore, miR-468-3p is a novel Runx2 regulator with key physiological action in BF and OD.

Periodontitis is associated with multiple systemic diseases and can cause bone loss. Porphyromonas gingivalis (P. gingivalis) is one of the most virulent periodontal pathogens. Icariin is a flavonoid extracted from the traditional Chinese herbal medicine Herba Epimedii, and can regulate bone metabolism. However, its effects on promoting bone metabolism have not been fully elucidated. In this experiment, we infected MC3T3-E1 cells with P. gingivalis. Flow cytometry results show that persistent bacterial infection does not affect cell proliferative activity. Western blotting, ALP activity detection, mineral content determination, and immunofluorescence blotting confirmed that icariin improved osteogenic differentiation in the inflammatory state, and this effect may be more obvious in the early stage of osteogenic differentiation. The antibacterial assays, ROS and MMP fluorescence assays demonstrated that icariin exerted a significant inhibitory effect on bacterial growth and attenuated the inflammatory response in bacterial-infected conditions. The results of in vivo experiments in animals further validated the excellent properties exerted by icariin in the repair of bone defects. Additionally, in the P. gingivalis-infected state, icariin exert a regulatory effect on EphA2-RhoA signaling pathway to augment osteogenic differentiation. These exciting findings suggest that icariin holds significant potential for therapeutic application in the management of periodontal bone loss.

Why severe injury to the central nervous system (CNS) triggers the development of large neurogenic heterotopic ossifications (NHOs) within periarticular muscles remains unknown. We report that spinal cord injury (SCI) triggers a rapid corticosterone spike in mice, which is causal for NHO development because treatments with corticosterone or the synthetic glucocorticoid (GC) receptor (GR) agonist dexamethasone are sufficient to trigger heterotopic ossification and upregulate the expression of osteoinductive and osteogenic differentiation genes in injured muscles even without SCI. The central role for GR signaling in causing NHO is further demonstrated in mice deleted for the GR gene (Nr3c1), which no longer develop NHO after SCI. Furthermore, administration of clinical GR antagonists inhibits NHO development in mice with SCI. This study identifies endogenous GC as causing pathological NHO after CNS injury and suggests that GR antagonists may be of prophylactic use to prevent NHO development in victims of severe CNS injuries.

As the population ages, the occurrence of osteoporosis is becoming more common. Diabetes mellitus is one of the factors in the development of osteoporosis. Compared with the general population, the incidence of osteoporosis is significantly higher in diabetic patients. Diabetic osteoporosis (DOP) is a metabolic bone disease characterized by abnormal bone tissue structure due to hyperglycemia and insulin resistance, reduced bone strength and increased risk of fractures. This is a complex mechanism that occurs at the cellular level due to factors such as blood vessels, inflammation, and hyperglycemia and insulin resistance. Although the application of some drugs in clinical practice can reduce the occurrence of DOP, the incidence of fractures caused by DOP is still very high. Extracellular vesicles (EVs) are a new communication mode between cells, which can transfer miRNAs and proteins from mother cells to target cells through membrane fusion, thereby regulating the function of target cells. In recent years, the role of EVs in the pathogenesis of DOP has been widely demonstrated. In this article, we first describe the changes in the bone microenvironment of osteoporosis. Second, we describe the pathogenesis of DOP. Finally, we summarize the research progress and challenges of EVs in DOP.

The present study investigated the effect of connexin 43 (Cx43) on the regulation of osteogenic differentiation of rat bone marrow-derived mesenchymal stem cells (BMSCs) using low-frequency-pulsed electromagnetic fields (LPEMF). The BMSCs were isolated and cultured in vitro using adherent whole-bone marrow cultures. CCK-8 assay was used to detect the effects of LPEMF on the proliferation ability of BMSCs and alkaline phosphatase (ALP) activity and the levels of osteogenic marker genes were detected to evaluate the osteogenic ability change following LPEMF treatment. Lentiviral vector-mediated RNA interference was transfected into BMSCs to inhibit the expression of Cx43 and western blotting was used to detect Cx43 expression. The BMSCs showed the highest proliferation following LPEMF treatment at 80 Hz for 1 h. The results of ALP activity, osteogenic marker genes and Alizarin Red S staining showed that the osteogenic ability was notably increased following LPEMF treatment at 80 Hz for 1 h. Cx43 expression increased during the osteogenic differentiation of BMSCs following LPEMF treatment at 80 Hz. The enhanced osteogenic differentiation of the LPEMF-treated BMSCs were partially reversed when Cx43 expression was inhibited. LPEMF may promote the osteogenic differentiation of BMSCs by regulating Cx43 expression and enhancing osteogenic ability.

Osteoporosis (OP) is a metabolic disease characterized by low bone mineral mass owing to osteoblast dysfunction. Eucommia ulmoides Oliver (EuO) is a Chinese herbal medicine traditionally used to treat OP. Here, a polysaccharide purified from the EuO cortex (EuOCP3) was administered to OP mice constructed with dexamethasone (Dex) to investigate its anti-OP activity. EuOCP3 significantly improved Dex-induced bone microarchitecture destruction, increased osteoblast numbers and surface, and stimulated an increase in the expression of osteoblast differentiation markers in the femurs of OP mice. Furthermore, EuOCP3 was applied to MC3T3-E1 cells to further explore its effects on osteoblast differentiation. EuOCP3 significantly promoted osteoblast differentiation and increased the level of phosphorylated extracellular signal-regulated kinase1/2 (ERK1/2) and SMAD1/5/8. The EuOCP3-mediated enhancement of osteoblast differentiation-related proteins and phosphorylated SMAD1/5/8 expression levels was strongly suppressed by an ERK inhibitor (PD98059), which confirmed the critical role of ERK signaling in EuOCP3-induced osteoblast differentiation. In summary, EuOCP3 can stimulate bone formation by improving osteoblast differentiation via ERK/BMP-2/SMAD signaling, indicating the potential use of EuOCP3 as a functional ingredient in food products for anti-OP treatment.

Vascular calcification (VC) is a complex process involving vascular smooth muscle cell (VSMC) osteogenic differentiation, inflammation, and extracellular vesicle (EV) calcification and communication networks. Gla rich protein (GRP) is a calcification inhibitor involved in most of these processes. However, the molecular mechanism of GRP in VC and the specific characteristics, cargo, and functionality of calcifying EVs require further elucidation. Here, we use a combination of human ex vivo aortic fragments and primary vascular smooth muscle cell (VSMC) models to obtain new information on GRP function in VC and EVs released by VSMCs. We demonstrate that GRP inhibits VSMC osteogenic differentiation through downregulation of bone-related proteins and upregulation of mineralization inhibitors, with decreased mineral crystallinity in EVs deposited into the tissue extracellular matrix (ECM). EVs isolated by ultracentrifugation at 30K and 100K from the cell media (CM) and deposited in the ECM from control (CTR) and mineralizing (MM) VSMCs were biochemically, physically, and proteomically characterized. Four different EV populations were identified with shared markers commonly present in all EVs but with unique protein cargo and specific molecular profiles. Comparative proteomics identified several regulated proteins specifically loaded into MM EV populations associated with multiple processes involved in VC. Functional analysis demonstrated that 30K and 100K ECM-MM EVs with higher calcium and lower GRP levels induced macrophage inflammation. Our findings reinforce the functional relevance of GRP in multiple VC processes and suggest that ECM EVs released under calcification stress function as a new signaling axis on the calcification-inflammation cycle.

Nanotherapeutic techniques are becoming increasingly important in the treatment of bone disorders owing to their targeted drug delivery. This study formulates zein nano coop composites containing chimeric antioxidants (ascorbic acid, luteolin, resveratrol, and coenzyme Q) (AZN) and evaluates its application in bone regeneration using osteoblasts and a Zebrafish osteoporosis model. In vitro experiments with human osteoblast-like MG63 cells showed enhancement of bone mineralization and regeneration. It further exhibited high biocompatibility in Zebrafish larvae, with increased calcium/phosphorus deposition and upregulation of osteogenic genes. The study has unequivocally demonstrated the potential of AZN in bone regeneration and fracture healing in both normal and osteoporosis models, underscoring the significance of this research. Further investigations using higher animal models are warranted to expand on these findings. The impact of this research seems far-reaching, with the possible development of new, effective, and safe treatment options for osteoporosis, addressing the limitations of the currently available treatments.

Hematopoiesis within the bone marrow (BM) is a complex and tightly regulated process predominantly influenced by immune factors. Aging, diabetes, and obesity are significant contributors to BM niche damage, which can alter hematopoiesis and lead to the development of clonal hematopoiesis of intermediate potential (CHIP). Genetic/epigenetic alterations during aging could influence BM niche reorganization for hematopoiesis or clonal hematopoiesis. CHIP is driven by mutations in genes such as Tet2, Dnmt3a, Asxl1, and Jak2, which are associated with age-related hematological malignancies.

This literature review aims to provide an updated exploration of the functional aspects of BM niche cells within the hematopoietic microenvironment in the context of age-related hematological malignancies. The review specifically focuses on how immunological stressors modulate different signaling pathways that impact hematopoiesis.

An extensive review of recent studies was conducted, examining the roles of various BM niche cells in hematopoietic stem cell (HSC) trafficking and the development of age-related hematological malignancies. Emphasis was placed on understanding the influence of immunological stressors on these processes.

Recent findings reveal a significant microheterogeneity and temporal stochasticity of niche cells across the BM during hematopoiesis. These studies demonstrate that niche cells, including mesenchymal stem cells, osteoblasts, and endothelial cells, exhibit dynamic interactions with HSCs, significantly influenced by the BM microenvironment as the age increases. Immunosurveillance plays a crucial role in maintaining hematopoietic homeostasis, with alterations in immune signaling pathways contributing to the onset of hematological malignancies. Novel insights into the interaction between niche cells and HSCs under stress/aging conditions highlight the importance of niche plasticity and adaptability.

The involvement of age-induced genetic/epigenetic alterations in BM niche cells and immunological stressors in hematopoiesis is crucial for understanding the development of age-related hematological malignancies. This comprehensive review provides new insights into the complex interplay between niche cells and HSCs, emphasizing the potential for novel therapeutic approaches that target niche cell functionality and resilience to improve hematopoietic outcomes in the context of aging and metabolic disorders.

This review introduces novel concepts regarding the plasticity and adaptability of BM niche cells in response to immunological stressors and epigenetics. It proposes that targeted therapeutic strategies aimed at enhancing niche cell resilience could mitigate the adverse effects of aging, diabetes, and obesity on hematopoiesis and clonal hematopoiesis. Additionally, the review suggests that understanding the precise temporal and spatial dynamics of niche-HSC interactions and epigenetics influence may lead to innovative treatments for age-related hematological malignancies.